Early esophageal carcinoma: endoscopic ultrasonography using the Sonoprobe

BACKGROUND

Almost all cases of superficial esophageal carcinoma are curable by endoscopic mucosal resection (EMR), but a precise diagnosis of the depth of tumor invasion is necessary to assess the indication for EMR. Although endoscopy has a high rate of accuracy for diagnosing the depth of tumor invasion, it depends on the experience of the examiner in interpreting surface information of the lesions. Today, endoscopic ultrasonography (EUS) is one of the most powerful techniques for obtaining objective tomographic images of a tumor. The high-frequency ultrasound probe is appropriate for EUS in cases of superficial esophageal carcinoma because of its excellent near-field resolution that provides precise ultrasound images under direct control of the endoscope.

METHODS

We performed EUS with the Sonoprobe System in 85 cases of superficial esophageal carcinoma before treatment and evaluated the resected specimens histopathologically. We interpreted the depth of tumor invasion based on our fundamental studies of ultrasonograms taken with a 20-MHz probe.

RESULTS

The clinical usefulness of the Sonoprobe with linear and radial scanning modes is due to its capacity to differentiate between mucosal and submucosal carcinoma by means of analyses of the muscularis mucosae. Although a clear assessment of microinvasion and lymphoid hyperplasia surrounding the tumor of interest remains speculative, the diagnostic accuracy rate for 96 lesions of superficial esophageal carcinoma reached 93% in terms of differentiating between mucosal from submucosal carcinoma.

CONCLUSION

EUS with the Sonoprobe can play an important role in the pretreatment diagnosis of superficial esophageal carcinomas.

Activity-dependent change in the protein level of brain-derived neurotrophic factor but no change in other neurotrophins in the visual cortex of young and adult ferrets

Neurotrophins are suggested to play a role in activity-dependent plasticity of visual cortex during the critical period of postnatal development. Thus, the concentration of neurotrophins in the cortex is expected to change with development and/or with alteration in neuronal activities. To test this, we measured protein levels of nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4/5 in visual cortex of young (postnatal day 38-46, at the peak of the critical period) and adult ferrets with two-site enzyme-immunoassay systems. Measurements were carried out also in somatosensory cortex, hippocampus and cerebellum as control. With development the level of brain-derived neurotrophic factor did not significantly change, while those of the other neurotrophins changed in the visual cortex. A blockade of visual inputs for 24 h by an injection of tetrodotoxin into both eyes significantly decreased brain-derived neurotrophic factor protein level in the visual cortex, but not in the other regions in both young and adult ferrets. On the other hand, no significant decrease was seen in the protein level of the other neurotrophins in the visual cortex of young and adult ferrets. A monocular injection of tetrodotoxin in young ferrets resulted in the reduction of brain-derived neurotrophic factor by approximately half that by binocular injection. The degree of the decrease in the contralateral cortex to the injected eye was significantly larger than that in the ipsilateral cortex, reflecting that the contralateral eye is dominantly represented in the cortex in ferrets. Blockade of cortical neuronal activities by a GABA(A) receptor agonist led to a remarkable reduction of brain-derived neurotrophic factor protein in the visual cortex. These results suggest that the level of brain-derived neurotrophic factor protein in visual cortex is regulated by activities of cortical neurons.

Inducible cross-tolerance to herbicides in transgenic potato plants with the rat CYP1A1 gene

A gene of the enzyme involved in xenobiotic metabolism in mammalian liver was introduced into potato to confer inducible herbicide tolerance. A rat cytochrome P450 monooxygenase, CYP1A1 cDNA, was kept under the control of the tobacco PR1a promoter in order to apply the system of chemical inducible expression using the plant activator Benzothiadiazole (BTH). Transgenic plants were obtained based on the kanamycin resistance test and PCR analysis. Northern-blot analysis revealed the accumulation of mRNA corresponding to rat CYP1A1 in the transgenic plants treated with BTH (3.0 micro mol/pot), whereas no accumulation of the corresponding mRNA occurred without BTH treatment. These transgenic plants also produced a protein corresponding to CYP1A1 in the leaves by BTH treatment. The transgenic plants with BTH application showed a much-higher tolerance to the phenylurea herbicides chlortoluron and methabenzthiazuron than non-transgenic plants. These findings indicated that the ability of metabolizing the two herbicides to less-toxic derivatives was displayed in the transgenic plants after BTH treatment. Transgenic plants harboring the CYP1A1 cDNA fused with the yeast P450 reductase (YR) gene under the control of PR1a were also produced. Although the plants showed a lower expression level of the fused gene than transgenic plants with CYP1A1 cDNA alone, they were tolerant to herbicides. These facts suggested that the CYP1A1 enzyme fused with YR showed a higher specific activity than CYP1A1 alone. This study demonstrated that the mammalian cDNA for the de-toxification enzyme of herbicides under the control of the PR1a promoter conferred chemical-inducible herbicide tolerance on potato.

Hepatocyte growth factor secreted by periodontal ligament and gingival fibroblasts is a major chemoattractant for gingival epithelial cells

To ascertain whether periodontal fibroblasts could be involved in the pathogenesis of periodontal pocket formation, the chemotactic activity of periodontal ligament fibroblast-conditioned medium (PLF-CM) and gingival fibroblast-conditioned medium (GF-CM) for gingival epithelial cells was examined using a modified Boyden chamber assay. Both PLF-CM and GF-CM possessed significant chemotactic activity, which was decreased markedly by treatment with anti-human hepatocyte growth factor (HGF) neutralizing antibody. Furthermore, the chemotactic activity of PLF-CM and GF-CM was well correlated with HGF content. These results show that PLF and GF secrete an HGF-like factor, and suggest that such a factor derived from periodontal fibroblasts might play a role in epithelial apical migration in periodontitis.

Brain-derived neurotrophic factor induces long-lasting potentiation of synaptic transmission in visual cortex in vivo in young rats, but not in the adult

Brain-derived neurotrophic factor (BDNF) rapidly enhances excitatory synaptic transmission in cortical slices. To date, however, a question of how long such an action persists remains unanswered as it is hard to record synaptic responses longer than several hours in slice preparations. To address this question and to investigate possible age-dependency of the action, we analysed effects of a brief application of BDNF and nerve growth factor (NGF) on field potentials of visual cortex in rats of postnatal days 13-17 and 19-24 and in the adulthood for 10-24 h. Evoked potentials to stimulation of the lateral geniculate nucleus were recorded simultaneously from two cortical sites into which the neurotrophin and control solution were injected. An application of BDNF induced a slowly developing increase in the field potential amplitude in young rats. The amplitude attained a plateau level 3-4 h after the infusion; 139 +/- 26% (mean +/- SD) and 132 +/- 21% of the baseline in the rats at P13-17 and P19-24, respectively. This potentiation remained stable from 4 to 8 h, then gradually decreased to the baseline 15-16 h after the infusion. NGF applied in the same way did not induce potentiation. An inhibitor of BDNF receptors blocked the potentiation when it was applied immediately after the BDNF application, but was not effective about 2 h later. In the adults, BDNF did not potentiate field potentials. These results indicate that BDNF induces synaptic potentiation lasting for several hours only in the developing cortex through processes downstream of receptor activation.

High- and moderately high-methionine uptake demonstrated by PET in a patient with a subacute cerebral infarction

In patients with cerebral tumors, high accumulations of L-methyl-11C-methionine (11C-Met) have been reported in some cases of cerebral ischemic disease, but no high accumulations of 11C-Met in areas where only transient arterial occlusions are most likely to occur have been reported. Herein we present a case of a high accumulation of 11C-Met in an area of frontal interhemispheric cerebral infarction and a moderately high accumulation with an unclear margin in a distant frontal convexity area. A craniotomy revealed a subacute stage of cerebral infarction in the interhemispheric lesion, and an ischemic change in the distant convexity area. Sixteen months after onset, CT scans demonstrated an infarction area in the interhemispheric lesion only, and no atrophic changes were observed in the distant convexity area indicating that no serious tissue damage had occurred.

Melatonin therapy for REM sleep behavior disorder

Rapid eye movement sleep behavior disorder (RBD) is a parasomnia with clinical symptoms that include punching, kicking, yelling and leaping out of bed in sleep. Polysomnographic (PSG) finding showed REM sleep without muscle atonia. Clonazepam is generally used for treating RBD symptoms but melatonin was reported to be effective so we reconfirmed the effect of melatonin on RBD patients in the present study. We used melatonin (3-9 mg/day) which could ameliorate problem sleep behaviors remarkably, as well as %tonic activity in PSG variables. In the present study, melatonin was reconfirmed to be effective in RBD symptoms, especially for patients with low melatonin secretion, while its mechanism was not clearly known in the present study.

Profiles of cytokine expression in radicular cyst-lining epithelium examined by RT-PCR

Levels of messenger RNA (mRNA) extracted from five samples of radicular cyst-lining epithelium were analyzed for cytokines, growth factors and epithelial cell growth-related receptors by RT-PCR. All five samples expressed IL-1alpha, -1beta, IL-6, IL-8, IL-11, TGF-beta1, PDGF-A and aFGF, and receptors for EGF (c-erbB), KGF, HGF (c-met) and IL-6. Some of the specimens expressed MIP-1alpha, RANTES, GM-CSF, M-CSF, TNF-alpha, PDGF-B and bFGF, but no expression of IL-2, IL-4, IFN-gamma, IGF-I, EGF and KGF was detected. These results indicate that radicular cyst-lining epithelium, which is considered to be identical to the cell rests of Malassez, may play a role in periodontal pocket formation or apical cyst formation by interaction with surrounding connective tissue or hematopoietic cells through the expression of various cytokines.

Induced expression of sarcotoxin IA enhanced host resistance against both bacterial and fungal pathogens in transgenic tobacco

We demonstrate here that induced expression of sarcotoxin IA, a bactericidal peptide from Sarcophaga peregrina, enhanced the resistance of transgenic tobacco plants to both bacterial and fungal pathogens. The peptide was produced with a modified PR1a promoter, which is further activated by salicylic acid treatment and necrotic lesion formation by pathogen infection. Host resistance to infection of bacteria Erwinia carotovora subsp. carotovora and Pseudomonas syringae pv. tabaci was shown to be dependent on the amounts of sarcotoxin IA expressed. Since we found antifungal activity of the peptide in vitro, transgenic seedlings were also inoculated with fungal pathogens Rhizoctonia solani and Pythium aphanidermatum. Transgenic plants expressing higher levels of sarcotoxin were able to withstand fungal infection and remained healthy even after 4 weeks, while control plants were dead by fungal infection after 2 weeks.

Agrobacterium-mediated transformation of monocot and dicot plants using the NCR promoter derived from soybean chlorotic mottle virus

The NCR promoter (PNCR) from soybean chlorotic mottle virus (SoyCMV) was used to express the selectable marker, neomycin phosphotransferase (nptII) gene, in Agrobacterium-mediated transformation of both monocot (rice) and dicot (tobacco) plants. A multi-cloning site for insertion of a gene of interest into the binary vector pTN is located proximal to the right border region of T-DNA. When chimeric genes under the control of other strong promoters were located in a head-to-head orientation to the PNCR-nptII gene, kanamycin-resistant tobacco shoots were generated more efficiently than when using the original pTN vectors. This suggests that the enhancer-like sequences in the promoters adjacent to PNCR may promote expression of the PNCR-nptII gene.

Hepatocyte growth factor is a predominant chemoattractant for gingival epithelial cells produced by radicular cyst-derived fibroblast-like cells

To clarify whether fibroblasts could be involved in the pathogenesis of periodontal pocket formation, the chemotactic activity of radicular cyst-derived fibroblast-like cell (RCF)-conditioned medium (RCF-CM) for gingival epithelial cells was examined using a modified Boyden chamber assay. RCF-CM possessed significant chemotactic activity, which was decreased markedly by treatment with anti-human hepatocyte growth factor (HGF) antibody. Furthermore, the chemotactic activity of RCF-CM was well correlated with HGF content. These results show that the RCF secrete an HGF-like factor, and suggest that such a factor derived from periodontal fibroblasts might play a role in epithelial apical migration in periodontitis.

Brain-derived neurotrophic factor expands ocular dominance columns in visual cortex in monocularly deprived and nondeprived kittens but does not in adult cats

Segregation and stabilization of thalamocortical afferents to eye-specific patches, so-called "ocular dominance (OD) columns," in visual cortex are hypothesized to be based on activity-dependent competition for trophic factors such as brain-derived neurotrophic factor (BDNF) between afferents representing the two eyes during the critical period of postnatal development. To test this hypothesis we observed effects of an intracortical infusion of BDNF on OD columns in monocularly deprived kittens and also compared effects between normal kittens and adult cats. BDNF had a hypertrophic action on afferents irrespective of visual inputs so that it desegregated OD columns in the visual cortex of deprived and normal kittens, but this action was not seen in the adults, substantiating its hypothesized trophic role in plasticity of OD columns in the developing visual cortex.

Ribulose-1,5-bisphosphate carboxylase/oxygenase from an ammonia-oxidizing bacterium, Nitrosomonas sp. K1: purification and properties

The ammonia-oxidizing chemoautotrophic Nitrosomonas sp. strain K1 exhibited marked ribulose-1,5-bisphosphate carboxylase (RubisCO) activity. The RubisCO [EC 4.1.1.39] was purified as an electrophoretically homogeneous protein. The molecular mass of the enzyme was estimated to be about 460 kDa by gel filtration, and it consists of two subunits [large (L): 52.2 kDa; small (S): 13.3 kDa] as demonstrated by SDS-PAGE. This confirmed that the enzyme has an L(8)S(8) structure. The K(m) values of the enzyme for RuBP, NaHCO3, and Mg2+ were estimated to be 0.112, 0.415, and 1.063 mM, respectively. The optimum pH and temperature for its activity were approximately 7.0 and 45 degrees C. The enzyme was stable up to 45 degrees C and in a pH range from 7.0-9.0 (4 degrees C, 48 h). The enzyme activity was inhibited by Cu2+, Hg2+, N-ethylmaleimide, p-chloromercuribenzoate, and SDS (0.1 mM). The activity was also inhibited by ammonium sulfate at high concentrations (38-303 mM) but the stability of the enzyme showed no inhibition at the same ammonium sulfate concentrations. The N-terminal amino acid sequences of the large and small subunits are AIKTYQAGVKEYRQTYW QPDYVPL and AIQAYHLTKKYETFSYLPQM, respectively.

A case of interleukin-6-producing malignant fibrous histiocytoma originating in the heart

Primary cardiac malignant fibrous histiocytoma is extremely rare and its pathophysiological characteristics remain largely unknown. We treated a female patient with persistent fever and disseminated intravascular coagulation. Since ultrasonic echocardiography revealed the presence of a cardiac tumor and her serum interleukin-6 level was elevated, we speculated she had a cardiac myxoma. Histological examination of the surgically resected specimen, however, revealed that the tumor was malignant fibrous histiocytoma. Although her disseminated intravascular coagulation and heart failure were transiently improved after operation, local recurrence and systemic metastasis occurred and she died 7 weeks after operation. Using the autopsied specimen, we examined whether the malignant fibrous histiocytoma constitutively synthesized interleukin-6. The interleukin-6 content in the tumor was high, consistent with interleukin-6 production by the tumor. This was confirmed by immunohistochemical analysis. To our knowledge, this is the first report demonstrating interleukin-6 production by a cardiac malignant fibrous histiocytoma.

Enhanced resistance to bacterial diseases of transgenic tobacco plants overexpressing sarcotoxin IA, a bactericidal peptide of insect

Sarcotoxin IA is a bactericidal peptide of 39 amino acids found in the common flesh fly, Sarcophaga peregrina. Many agronomically important bacteria in Japan are killed by this peptide at sub-micro molar levels, and the growth of tobacco and rice suspension cultured cells is not inhibited with less than 25 microM. Transgenic tobacco plants which overexpress the peptide, i.e. over 250 pmol per gram of fresh leaf, under the control of a high expression constitutive promoter showed enhanced resistance to the pathogens for wild fire disease (Pseudomonas syringae pv. tabaci) and bacterial soft rot disease (Erwinia carotovora subsp. carotovora).

Photosensitive seizures provoked while viewing "pocket monsters," a made-for-television animation program in Japan

PURPOSE

To describe the recent epidemic of photosensitive seizure that occurred in relation to an episode of the television animation program "Pocket Monsters," we report four patients who experienced seizures while watching the episode in question. We also report some technical aspects of the program episode.

METHODS

We investigated the clinical symptoms of the four patients and performed routine EEGs with intermittent photic stimulation (IPS). If IPS provoked no photoparoxysmal response (PPR) during the routine EEG examination, a second EEG was performed with the photic stimulator placed 10 cm from the patient's eyes. In addition, we reviewed the "Pocket Monsters" episode, focusing our attention on the visual techniques used with reference to the Independent Television Commission (ITC) guidelines.

RESULTS

One patient who had myoclonic jerks before the convulsion in question was diagnosed as having juvenile myoclonic epilepsy, and the diagnosis of another patient was pure photosensitive epilepsy. The remaining two patients had their first seizures, which could be occasional seizures, and we therefore could not reach a diagnosis of epilepsy. In our four patients, only one showed PPR on the routine EEG. Two patients revealed PPR on the second EEG, and the remaining patient showed no PPR. Rapid changes in color are believed to be responsible for the photosensitive seizures because all four patients had seizures at around 18:50, when seconds of deep red and bright blue flashes, alternating at a frequency of 12 Hz, were shown.

CONCLUSIONS

Regulations for technical aspects of children's programming, including the use of colors, are urgently needed in Japan to prevent a repeated incident. In addition, the IPS procedure needs to be standardized, especially for patients who are suspected to have photosensitivity.

Role of the isoprenyl tail of ubiquinone in reaction with respiratory enzymes: studies with bovine heart mitochondrial complex I and Escherichia coli bo-type ubiquinol oxidase

The hydrophobic isoprene tail of ubiquinone-2 (Q2) exihibits binding specificity in redox reactions with bovine heart mitochondrial complex I (Ohshima, M., Miyoshi, H., Sakamoto, K., Takegami, K., Iwata, J., Kuwabara, K., Iwamura, H., and Yagi, T. (1998) Biochemistry 37, 6436-6445) and the Escherichia coli bo-type ubiquinol oxidase (Sakamoto, K., Miyoshi, H., Takegami, K., Mogi, T., Anraku, Y., and Iwamura, H. (1996) J. Biol. Chem. 271, 29897-29902). To identify the structural factor(s) of the diprenyl tail of Q2 governing the specific interaction with these enzymes, we synthesized a series of novel Q2 analogues in which only one of the structural factors of the diprenyl tail was systematically modified. In bovine complex I, the presence of the methyl branch and the pi-electron system in the first isoprene unit are responsible for high-affinity binding of Q2 to the ubiquinone reduction site, which results in a low Km and kcat values of Q2 reduction. The position of the methyl group in the tail is strictly recognized by the enzyme. In contrast to complex I, in bo-type ubiquinol oxidase, either of the two pi-electron systems in the tail is required for high-affinity binding of Q2H2 to the enzyme, while the presence of the methyl branch and the location of the pi-electron systems are not strictly recognized by the enzyme. We concluded that the role of the ubiquinone tail is not simply the enhancement of the hydrophobicity of the molecule and that molecular recognition of the tail by the quinone redox site differs among the respiratory enzymes.

Overexpression of CD44 variant transcripts in rat transplantable thyroid carcinoma lines demonstrating lung metastasis

Expression of CD44 isoforms has been reported to be involved in tumor invasion and metastasis in both rodents and man. We earlier documented establishment of rat transplantable thyroid carcinoma lines in vivo from primary lesions induced by a chemical carcinogen. Recently, two lines (L1a-M4 and L2a-M6) were found to spontaneously metastasize to the lung after subcutaneous transplantation. To determine whether CD44 splice variants contribute to their metastatic spread, carcinoma lines with and without lung metastasis were evaluated quantitatively and qualitatively using RT-PCR followed by hybridization and immunohistochemical analyses. The L1a-M4 and L2a-M6 metastatic lines showed significant overexpression of CD44 variant transcripts containing variant exons v4-v6 or v9-v10/v8-v10, respectively, with concomitant reduced levels of standard transcripts. Investigation of the precise composition of alternatively spliced mRNA in normal tissues and carcinoma lines using an exon-specific RT-PCR method, revealed major chain variant transcripts containing v2/v3, v4-v6, v7-v10 and v8-v10 in all specimens. Applying the same RT-PCR analysis to mRNAs derived from cultured cell lines, demonstrated essentially the same pattern. The results suggest that quantitative increase rather than qualitative change in CD44 variant isoforms is associated with the pathogenesis of lung metastasis of rat thyroid carcinomas.

Essential structural factors of annonaceous acetogenins as potent inhibitors of mitochondrial complex I

The annonaceous acetogenins are the most potent of the known inhibitors of bovine heart mitochondrial complex I. These inhibitors act, at the terminal electron transfer step of the enzyme, in a similar way to the usual complex I inhibitors, such as piericidin A and rotenone; however, structural similarities are not apparent between the acetogenins and these known complex I inhibitors. A systematic set of isolated natural acetogenins was prepared and examined for their inhibitory actions with bovine heart mitochondrial complex I to identify the essential structural factors of these inhibitors for the exhibition of potent activity. Despite their very potent activity, the structural requirements of the acetogenins are not particularly rigid and remain somewhat ambiguous. The most common structural units, such as adjacent bis-tetrahydrofuran (THF) rings and hydroxyl groups in the 4- and/or 10-positions, were not essential for exhibiting potent activity. The stereochemistry surrounding the THF rings, surprisingly, seemed to be unimportant, which was corroborated by an exhaustive conformational space search analysis, indicating that the model compounds, with different stereochemical arrangements around the THF moieties, were in fairly good superimposition. Proper length and flexibility of the alkyl spacer moiety, which links the THF and the alpha, beta-unsaturated gamma-lactone ring moieties, were essential for the potent activity. This probably results from some sort of specific conformation of the spacer moiety which regulates the two ring moieties to locate into an optimal spatial position on the enzyme. It is, therefore, suggested that the structural specificity of the acetogenins, required for optimum inhibition, differs significantly from that of the common complex I inhibitors in which essential structural units are compactly arranged and conveniently defined. The structure-activity profile for complex I inhibition is discussed in comparison with those for other biological activities.

Characterization of the ubiquinone reduction site of mitochondrial complex I using bulky synthetic ubiquinones

A wide variety of alkyl derivatives of Q2 (6-geranyl-2, 3-dimethoxy-5-methyl-1,4-benzoquinone) and DB (6-n-decyl-2, 3-dimethoxy-5-methyl-1,4-benzoquinone), in which methoxy groups of the 2- and/or 3-positions of the quinone ring were replaced by other bulky alkoxy groups from ethoxy to butoxy, were prepared by novel synthetic procedures. Electron-accepting activities of the bulky quinones were investigated with bovine heart mitochondrial complex I and its counterpart of Paracoccus denitrificans(NDH-1) to elucidate structural and functional features of the quinone reduction site of the enzymes. The bulky quinone analogues served as sufficient electron acceptors from the physiological quinone reduction site of bovine complex I. Considering the very poor activities of even the ethoxy derivatives as substrates for other respiratory enzymes such as mitochondrial complexes II and III [He, D. Y., Gu, L. Q., Yu, L., and Yu, C. A. (1994) Biochemistry 33, 880-884], this result indicated that the quinone reduction site of bovine complex I is spacious enough to accommodate bulky exogenous substrates. In contrast to bovine complex I, bulky quinone analogues served as poor electron acceptors with Paracoccus NDH-1. These observations indicated that bovine complex I recognizes the substrate structure with poor specificity. The substituent effects in the 2- and 3-positions of the quinone ring on the electron-transfer activity with bovine complex I differed significantly between Q2 and DB series despite having the same total number of carbon atoms in the side chain. The inhibitory effect involving Q2 due to its geranyl side chain was markedly diminished by structural modifications of the quinone ring moiety. These findings indicate that the side chain plays a specific role in the redox reaction and that the quinone ring and side-chain moieties contribute interdependently to binding interaction. Moreover, structural dependency of the proton-pumping activity of the quinone analogues was comparable to that of the electron-transfer activity with bovine complex I, indicating that the mechanism of redox-driven proton-pumping does not differ depending upon the substrate structure.

Role of NMDA receptors in the propagation of excitation in rat visual cortex as studied by optical imaging

To examine the role of the N-methyl-D-aspartate (NMDA) type of glutamate receptors in the propagation of information in visual cortex, optical imaging with high spatial and temporal resolution of neuronal activity was used in cortical slices of rats. Single-shock stimulation of the white matter elicited a vertical propagation of excitation toward the cortical surface simultaneously with a horizontal spread of excitation in lower layers. The horizontal spread in upper layers occurred subsequent to the vertical spread reaching these layers. The results from perfusion of Ca2+-free medium and application of an antagonist of non-NMDA receptors indicated that this intracortical propagation of signals is due mostly, if not exclusively, to the postsynaptic excitation of cortical neurons. Blockade of NMDA receptors attenuated the rising and peak phases of the upper horizontal spread, but did not affect those of the lower horizontal or vertical propagation of excitation. Perfusion with Mg2+-free solution enhanced the upper horizontal spread, but in most cases did not significantly change the spread of excitation in the other pathways. These results indicate that NMDA receptors are involved in the flow of information in the upper layers of visual cortex, and further suggest that this propagation of activity is mediated mainly by horizontal connections intrinsic to the upper layers.

Circadian rhythms of hormone concentrations in alcohol withdrawal

We investigated the circadian rhythm of hormones (cortisol, melatonin) in alcoholic patients during and 1 month after alcohol withdrawal. Patients with delirium tremens had irregular serum hormone concentration rhythms during withdrawal, which normalized after the withdrawal period. Patients without delirium tremens had normal circadian rhythms even during the withdrawal period. We speculated that the disturbance of the biological oscillator, in terms of the decline of synchronizing function or the decrease in synchronizing factors, caused abnormal circadian rhythms of hormone release during delirium tremens.