Steady-State Cortico-Cortical Evoked Potential

PURPOSE

The present study evaluated the utility of the steady-state responses of cortico-cortical evoked potentials (SSCCEPs) and compared them with the responses of conventional CCEPs.

METHODS

Eleven patients with medically intractable focal epilepsy who underwent the implantation of subdural electrodes or stereoelectroencephalography were enrolled. Conventional CCEPs were obtained by averaging responses to alternating 1-Hz electrical stimuli, and 5-Hz stimuli were delivered for recording SSCCEPs. The distribution of SSCCEPs was assessed by a frequency analysis of fast Fourier transform and compared with conventional CCEPs.

RESULTS

Steady-state responses of cortico-cortical evoked potentials were successfully recorded in areas consistent with conventional CCEPs in all patients. However, SSCCEPs were more easily disturbed by the 5-Hz stimulation, and small responses had difficulty generating SSCCEPs.

CONCLUSIONS

Steady-state responses of cortico-cortical evoked potentials may be a useful alternative to conventional CCEPs.

Deep learning for the diagnosis of mesial temporal lobe epilepsy

OBJECTIVE

This study aimed to enable the automatic detection of the hippocampus and diagnose mesial temporal lobe epilepsy (MTLE) with the hippocampus as the epileptogenic area using artificial intelligence (AI). We compared the diagnostic accuracies of AI and neurosurgical physicians for MTLE with the hippocampus as the epileptogenic area.

METHOD

In this study, we used an AI program to diagnose MTLE. The image sets were processed using a code written in Python 3.7.4. and analyzed using Open Computer Vision 4.5.1. The deep learning model, which was a fine-tuned VGG16 model, consisted of several layers. The diagnostic accuracies of AI and board-certified neurosurgeons were compared.

RESULTS

AI detected the hippocampi automatically and diagnosed MTLE with the hippocampus as the epileptogenic area on both T2-weighted imaging (T2WI) and fluid-attenuated inversion recovery (FLAIR) images. The diagnostic accuracies of AI based on T2WI and FLAIR data were 99% and 89%, respectively, and those of neurosurgeons based on T2WI and FLAIR data were 94% and 95%, respectively. The diagnostic accuracy of AI was statistically higher than that of board-certified neurosurgeons based on T2WI data (p = 0.00129).

CONCLUSION

The deep learning-based AI program is highly accurate and can diagnose MTLE better than some board-certified neurosurgeons. AI can maintain a certain level of output accuracy and can be a reliable assistant to doctors.

Motor Mapping with Functional Magnetic Resonance Imaging: Comparison with Electrical Cortical Stimulation

The aim of the present study was to evaluate motor area mapping using functional magnetic resonance imaging (fMRI) compared with electrical cortical stimulation (ECS). Motor mapping with fMRI and ECS were retrospectively compared in seven patients with refractory epilepsy in which the primary motor (M1) areas were identified by fMRI and ECS mapping between 2012 and 2019. A right finger tapping task was used for fMRI motor mapping. Blood oxygen level-dependent activation was detected in the left precentral gyrus (PreCG) /postcentral gyrus (PostCG) along the "hand knob" of the central sulcus in all seven patients. Bilateral supplementary motor areas (SMAs) were also activated (n = 6), and the cerebellar hemisphere showed activation on the right side (n = 3) and bilateral side (n = 4). Furthermore, the premotor area (PM) and posterior parietal cortex (PPC) were also activated on the left side (n = 1) and bilateral sides (n = 2). The M1 and sensory area (S1) detected by ECS included fMRI-activated PreCG/PostCG areas with broader extent. This study showed that fMRI motor mapping was locationally well correlated to the activation of M1/S1 by ECS, but the spatial extent was not concordant. In addition, the involvement of SMA, PM/PPC, and the cerebellum in simple voluntary movement was also suggested. Combination analysis of fMRI and ECS motor mapping contributes to precise localization of M1/S1.

Cortical regions and networks of hyperkinetic seizures: Electrocorticography and diffusion tensor imaging study

OBJECTIVE

The present study investigated the cortical areas and networks responsible for hyperkinetic seizures by analyzing invasive recordings and diffusion tensor imaging (DTI) tractography.

METHODS

Seven patients with intractable focal epilepsy in whom hyperkinetic seizures were recorded during an invasive evaluation at Sapporo Medical University between January 2012 and March 2020 were enrolled in the present study. Intracranial recordings were analyzed to localize seizure-onset zones (SOZs) and symptomatogenic zones (spread areas at clinical onset). DTI was used to identify the subcortical fibers originating from SOZs.

RESULTS

Ten SOZs were located in four areas: (1) the inferior parietal lobule (two SOZs in two patients), (2) temporo-occipital junction (three SOZs in two patients), (3) medial temporal area (three SOZs in three patients) and (4) medial/lateral frontal lobe (two SOZs in two patients). Symptomatogenic zones appeared to be the premotor area, basal temporal area, temporo-occipital junction, and the postcentral gyrus/supramarginal gyrus. The tractographic analysis revealed that the inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), middle longitudinal fasciculus (MLF), arcuate fasciculus (AF)/superior longitudinal fasciculus (SLF) II, III, and cingulum bundle may be associated with hyperkinetic seizures.

CONCLUSION

The present results suggest the cortical areas (the inferior parietal lobule, temporo-occipital junction, medial temporal area, and medial/lateral frontal lobe) and subcortical fibers (IFOF, ILF, MLF, AF/SLFII, III, and the cingulum bundle) responsible for generating hyperkinetic seizures.

Eye Movement Network Originating from Frontal Eye Field: Electric Cortical Stimulation and Diffusion Tensor Imaging

This study investigated the networks originating from frontal eye fields (FEFs) using electric cortical stimulation and diffusion tensor imaging (DTI). Seven patients with intractable focal epilepsy, in which FEFs were identified by electrical cortical stimulation, were enrolled in this study. Electric stimulation at 50 Hz was applied to the electrodes for functional mapping. DTI was used to identify the subcortical fibers originating from the FEFs with two regions of interests (ROIs) in the FEF and contralateral paramedian pontine reticular formation (PPRF). FEFs were found in the superior precentral sulcus (pre-CS) in six patients and superior frontal gyrus (SFG) in three patients. DTI detected fibers connecting FEFs and contralateral PPRFs, passing within the internal capsule. The fibers were located close to the lateral antero-superior border of the subthalamic nucleus (STN) and medial posterior border of the globus pallidus internus (GPi). This study found the characteristic subcortical networks of the FEF. These tracts should be noted to prevent complications of deep brain stimulation (DBS) of the STN or GPi.

Stroke Mimics and Chameleons from the Radiological Viewpoint of Glioma Diagnosis

Gliomas are sometimes difficult to differentiate from strokes and are often misdiagnosed on magnetic resonance imaging (MRI); thus, the terms “stroke mimics” and “stroke chameleons” have been introduced. In this study, we analyzed stroke mimics and stroke chameleons in glioma and discussed the diagnostic perplexity. We retrospectively reviewed cases that were removed from lesions that were considered to be brain tumors. This study enrolled 214 patients who underwent tumor resection for suspected glioma. Clinical characteristics and radiological findings of the patients were compared between the masquerade findings group, which was further divided into two groups: the stroke chameleons and stroke mimics according to their final diagnosis, and the intelligible findings group. Stroke chameleons and stroke mimics were significantly higher in age and smaller in lesion size than the intelligible findings group. In the multivariate analysis, the predictive factor of the masquerade finding group was higher age and smaller size. Stroke mimics group has a tendency to be higher rate of hyperintensity lesion on diffusion-weighted imaging (DWI) compared with stroke chameleons group. The average period from initial diagnosis to pathological diagnosis was 13.50 days in the stroke chameleons and 61.50 days in the stroke mimics, which proved significantly different. Proper diagnosis of glioma and stroke affects a patient’s prognosis, and should be diagnosed as soon as possible. However, stroke mimics and stroke chameleons caused by glioma can occur. Thus, the diagnosis of a stroke should take into consideration the possibility of a glioma in real clinical situations.

Target Selection of Directional Lead in Patients with Parkinson's Disease

Several structures including subthalamic nucleus (STN), the caudal zona incerta (cZI), the prelemniscal radiation (Raprl), and the thalamic ventral intermediate nucleus (Vim) have been reported to be useful for improving symptoms of Parkinson’s disease (PD). However, the effect of each target is still unclear. Therefore, we investigated each structure’s effects and adverse effects using a directional lead implanted in the posterior STN adjacent to the cZI and Raprl in two patients with tremor-dominant PD. In Case 1, maximal reduction of tremor was obtained by stimulation toward the Vim, and stimulation toward the thalamic reticular nucleus (TRN) reduced verbal fluency, but did not induce dysarthria. In Case 2, maximal reduction of tremor was obtained by stimulation toward the dorsal STN and Raprl. Maximal reduction of rigidity was achieved by stimulation toward the dorsal STN, Raprl, and cZI. Bradykiensia was improved by stimulation in all directions, but dyskinesia and dysarthria were evoked by stimulation toward the dorsal STN and cZI. The directional lead may elucidate the stimulation effect of each structure and broaden target selection depending on patients’ symptoms and adverse effects.

Effect of Cycling Thalamosubthalamic Stimulation on Tremor Habituation and Rebound in Parkinson Disease

BACKGROUND

Deep brain stimulation is an effective treatment for severe tremor in essential tremor and Parkinson disease (PD). However, progressive loss of the beneficial effects of deep brain stimulation may occur due to several factors.

CASE DESCRIPTION

We assessed the effects of different temporal patterns of cycling stimulation in the posterior subthalamic area, subthalamic nucleus, and the ventral intermediate nucleus of the thalamus in 3 PD patients with early decline of tremor suppression associated with severe tremor rebound.

CONCLUSIONS

Certain temporal patterns of cycling (10 seconds on/1 second off or 30 seconds on/5 seconds off, soft start off) were useful for treating tremor habituation and rebound and showed long-term tremor suppression. Cycling stimulation may prevent tremor habituation in PD patients with severe tremor rebound.

Anatomical and functional distribution of functional MRI language mapping

OBJECTIVE

The aim of the present study was to compare localization of the language cortex using electrical cortical stimulation (ECS) and functional magnetic resonance imaging (fMRI) to establish the relevance of fMRI language mapping.

METHODS

Language mapping with fMRI and functional ECS mapping were retrospectively compared in ten patients with refractory epilepsy who underwent fMRI language mapping and functional ECS mapping between June 2012 and April 2019. A shiritori task, a popular Japanese word chain game, was used for fMRI language mapping.

RESULTS

BOLD signal activation was observed in the left inferior frontal gyrus (including the pars opecularis and the pars triangularis), and superior temporal gyrus, which is a language-related area, as well as in the left superior and middle frontal gyri, the intraparietal sulcus, and fusiform gyrus. These results were compared with ECS to elucidate the functional role of the activated areas during fMRI language tasks. These activated areas included language areas, negative motor areas, supplementary motor areas (SMAs), and non-functional areas.

CONCLUSION

The activated areas of fMRI language mapping include language-related areas, the negative motor area, and SMAs. These findings suggest the involvement of language and higher order motor networks in verbal expression.

Combined deep brain stimulation and thalamotomy for tremor-dominant Parkinson's disease

Although deep brain stimulation (DBS) is an established treatment for Parkinson's disease, the long-term suppression of tremor is still a challenging issue. We report two patients with tremor-dominant Parkinson's disease (PD) treated with unilateral thalamotomy of the ventralis intermedius nucleus (Vim) combined with the subthalamic nucleus (STN)-DBS or the posterior subthalamic area (PSA)-DBS. One year after the surgery, thalamotomy of the area from the Vim to the PSA showed improvement not only in tremor but also in rigidity and akinesia. PSA- or STN-DBS with low intensity stimulation eliminated residual PD symptoms. Combined DBS and thalamotomy may provide long-term improvement of the majority of PD symptoms using lower therapeutic stimulation voltages.

Intraoperative Monitoring for Vagus Nerve Stimulation

BACKGROUND

Vagus nerve stimulation is a palliative treatment for patients with refractory epilepsy; however, the misplacement of electrodes may cause complications and thus needs to be avoided.

METHODS

We herein report an intraoperative monitoring technique to prevent the misplacement of electrodes. Endotracheal tube electrodes were inserted to record electromyographic activity from the vocal cords and identify the vagus nerve. Electromyography electrodes were placed on the sternomastoid muscle, sternohyoid muscle, geniohyoid muscle, and trapezius muscle to record muscle activities innervated by the ansa cervicalis. The vagus nerve and ansa cervicalis were electrically stimulated during surgery, and electromyography of the vocal cords and muscles innervated by the ansa cervicalis was recorded. The threshold of vagus nerve activation ranged between 0.05 and 0.75 mA.

RESULTS

The vagus nerve was successfully identified and differentiated from the nerve root of the ansa cervicalis using this technique.

CONCLUSIONS

Intraoperative monitoring of the vagus nerve and ansa cervicalis is useful for safe and effective vagus nerve stimulation.

Characteristics of cerebral hemodynamics assessed by CT perfusion in moyamoya disease

Due to the recent development of multidetector row computed tomography (CT), hemodynamic parameters can now be conveniently obtained with CT perfusion. The purpose of this study is to characterize the hemodynamic parameters of CT perfusion in moyamoya disease, and to discuss the differences in collateral circulation between moyamoya disease and atherosclerotic disease. A total of 16 hemispheric sides of 15 patients with moyamoya disease and 10 hemispheric sides of 9 patients with atherosclerotic disease who underwent bypass surgery were included. CT perfusion was performed with ¹²³I-IMP SPECT. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) values obtained by CT perfusion using standard singular value decomposition as the deconvolution algorithm in moyamoya disease were calculated. Preoperative values of these parameters were compared with those of atherosclerotic disease. Then, the postoperative changes of these parameters were analyzed. In the impaired side, CBF as measured by CT perfusion was correlated with that measured by ¹²³I-IMP SPECT. In moyamoya disease, CBV as measured by CT perfusion was significantly increased compared to in atherosclerotic disease, yet CBF was significantly decreased in atherosclerotic disease. Postoperatively, the asymmetry ratios of MTT were significantly improved, especially in atherosclerotic disease compared with moyamoya disease. On CT perfusion, the parameters included transit time and arrival time. CBV increase in moyamoya disease and postoperative improvement of MTT, especially in atherosclerotic disease, were unique characteristics in each. This might be due to the difference of collateral circulation and compensatory mechanisms between moyamoya disease and atherosclerotic disease.

[Effectiveness of hypoallergenic rice-by cast analysis]

Rice is the main food taken every day in Japan. We introduced hypoallergenic rice (95% of albumin and globulin were taken off by hyperpressure method) for 4 weeks to 7 atopic dermatitis patients (m 3, f 4), 11 mo-4 y 8 m (mean 3 y 2 m) who showed the RAST score of rice 1 or more. Stimulation Index by CAST (cellular antigen stimulation test) were compared before and after taking the rice (50-100 g). By albumin (0.1-100 micrograms/ml), maximum decreases of S.I. were 22.4-96.5% (mean 70.9) and by globulin maximum decreases of S.I. were (0.1-100 micrograms/ml) 33.3-97.0% (mean 72.9). In all the patients the skin conditions were improved.

Survey of human group C rotaviruses in Japan during the winter of 1992 to 1993

Fecal specimens from patients with acute diarrhea were collected from 10 prefectures in Japan over a 6-month period (November 1992 to April 1993), and the specimens that were negative for human group A rotaviruses were screened for the presence of human group C rotaviruses (CHRVs) by the reverse passive hemagglutination test. Of 784 specimens examined, 53 samples (6.8%) that were collected in 7 of 10 prefectures were positive for CHRV, indicating that CHRVs are widely distributed across Japan. Most of the CHRV isolates were detected in March and April, and CHRVs mainly prevailed in children ages 3 to 8 years. The genome electropherotypes of eight strains isolated in five individual prefectures were surprisingly similar to each other and were different from those of CHRV strains isolated to date. The outer capsid glycoprotein (VP7) gene homologies of the isolates retrieved in 1993 were subsequently analyzed by the dot blot hybridization method. As a result, the VP7 genes of the isolates revealed very high levels of homology not only with each other but also with the VP7 gene of the OK118 strain isolated in 1988. These results suggest that a large-scale outbreak of CHRV occurred during the winter of 1992 and 1993 in Japan.

Comparison of gelatin particle agglutination and hemagglutination inhibition tests for measles seroepidemiology studies

The prevalence of measles antibody in Japan was surveyed with a newly developed gelatin particle agglutination (PA) test, and the results compared with those of the hemagglutination inhibition (HI) test. The two age-distribution curves of the PA antibody-positive rates at > or = 1:8 and > or = 1:32 were almost the same in all the age groups, except the less-than-1-year-old group for which the rate at > or = 1:8 was higher than that at > or = 1:32 (p < 0.05, chi 2 test). In the vaccinated children, all groups older-than-1-year of age had antibody-positive levels of 96% or more. In contrast, in the unvaccinated children, there was a sharp increase in antibody-positive rates between the 1- and 4-year-old groups, indicative that about 80% of the children were infected by wild measles virus at these ages. A significant number of PA antibody-positive specimens were antibody-negative (< 1:8) by HI. The percentage of specimens in this category, PA (+) but HI (-), was greatest in infants less than one year old, and least in young children, but it increased with age to 97% of the HI (-) specimens from adults of more than 20 years of age. The PA test therefore detected some measles antibodies that HI could not. This test is simple and useful for making serosurveys in both developed and developing countries.

Protection of cynomolgus monkeys against infection by human T-cell leukemia virus type-I by immunization with viral env gene products produced in Escherichia coli

Protection against human T-cell leukemia virus type-I (HTLV-I) infection in cynomolgus monkeys, achieved by immunizing the animals with env gene products of HTLV-I produced in Escherichia coli, was evaluated. Four monkeys that had been immunized with the env product produced antibody against HTLV-I gp68 and gp46, and their sera were found to cause strong inhibition of syncytium formation of a cat fibroblast cell line induced by HTLV-I. Immunized and non-immunized monkeys were challenged with live MT-2 cells, a high HTLV-I-producer cell line. After challenge, all the control non-immunized monkeys were infected with HTLV-I, as judged by the frequent detection of HTLV-I-antigens in cultures of their peripheral blood mononuclear cells (PBMC), whereas no antigens were recovered from PBMC of immunized monkeys. These results indicate that humoral immunity against HTLV-I-envelope protein elicited by immunization with the polypeptides synthesized in bacteria protected the monkeys against primary infection with HTLV-I.

Development of adult T-cell leukemia-like disease in African green monkey associated with clonal integration of simian T-cell leukemia virus type I

Proviral integration of a simian retrovirus highly homologous to human T-cell leukemia virus type I was examined in cellular DNAs extracted from primary peripheral blood lymphocytes of 31 adult African green monkeys (Cercopithecus aethiops) that were seropositive for simian T-cell leukemia virus type I (STLV-I). Among these monkeys, one case with overt leukemia, showing pleomorphic leukemia cells similar to those in human adult T-cell leukemia (ATL), and five cases in a preleukemic state of ATL-like disease were found. Judging from the integration site of the provirus genome, primary lymphocytes of these leukemic or preleukemic cases contained monoclonally proliferated STLV-I-infected cells, whereas lymphocytes of other seropositive monkeys without hematological abnormalities were polyclonal, and those of seronegative monkeys did not contain the provirus. The restriction patterns with PstI ans SstI of most STLV-I proviruses were identical to those of the previous isolate from this species, but in three monkeys there was a deletion of one PstI site. From the correlation of the development of simian ATL-like disease with the monoclonal integration of the STLV-I provirus genome, it should be indicated that STLV-I has similar leukemogenicity to human T-cell leukemia virus type I, and so STLV-I infection in African green monkeys will be useful as an animal model of human ATL.

Hematologic abnormalities similar to the preleukemic state of adult T-cell leukemia in African green monkeys naturally infected with simian T-cell leukemia virus

Studies were made of the hematologic features of 23 adult African green monkeys (Cercopithecus aethiops) naturally infected with simian T-cell leukemia virus (STLV), which is closely related to human T-cell leukemia virus type I. None of the STLV-infected monkeys showed any clinical signs, but their absolute lymphocyte count and percentage of atypical lymphocytes were significantly higher than those of uninfected monkeys. Three STLV-infected monkeys had especially high percentages of atypical lymphocytes. Most of the atypical lymphocytes were small- or medium-sized lymphocytes with a lobulate or convoluted nucleus, and were very similar to the leukemic cells in human cases of adult T-cell leukemia (ATL), while other atypical cells were large lymphoblastoid cells. Both types of atypical cells were positive for Leu2a and Tac antigens, and expressed STLV antigen after short-term culture. These findings suggested the presence of a preleukemic state in these STLV-infected monkeys similar to that seen in human ATL, and indicated the value of this natural infection system as an animal model of ATL in humans.

Herpes simplex virus complement fixing antibody and herpes B virus serum neutralizing antibody in sera of wild and laboratory-bred cynomolgus monkeys

The result of the complement fixation (CF) test for the antibody to herpes simplex virus (HSV) in sera of the cynomolgus monkeys was compared with that of the neutralization test (NS) for the antibody to herpes B virus (HBV) in the same sera. Fifty-seven (74%) of 77 wild-originated monkeys were positive for HSV-CF, while 65 (84%) of the 77 animals were positive for HBV-SN. All of the 57 CF positive cases were also positive for HBV-SN. On the other hand, 30 (75%) of 40 laboratory-bred monkeys had neither HSV-CF antibody nor HBV-SN antibody. Remaining 10 of the 40 laboratory-bred animals were positive for HSV-CF. However, no HBV-SN antibody was detected in nine of the 10 HSV-CF positive animals. These results suggest that the HSV-CF test may be as satisfactory as the HSV-SN test as a practical measure for rough screening of HBV infection in the cynomolgus monkey in laboratories having no containment unit for handling HBV.

Adult T-cell leukemia-like disease in monkey naturally infected with simian retrovirus related to human T-cell leukemia virus type I

Spontaneous T-cell leukemia similar to human adult T-cell leukemia (ATL) was found in an African green monkey naturally infected with simian retrovirus closely related to human T-cell leukemia virus type I (HTLV-I). Monoclonal integration of the simian retrovirus was detected in the primary leukemic cells, suggesting an association of the retrovirus with ATL-like leukemia in the monkey.

Characterization of simian viruses isolated from wild cynomolgus monkeys

Twenty three strains of simian viruses isolated from nasopharyngeal swabs and respiratory tissues of cynomolgus monkeys showing mild symptoms of respiratory disorders were classified into three groups by their biological, serological and morphological characteristics. Thirteen strains classified as group 1 were judged to be enteroviruses. Four strains of group 2 and six strains of group 3 were identified as simian adenoviruses. Yields of the ten simian adenoviruses of groups 2 and 3 were compared in three continuous cell lines after several serial passages.

Enterovirus type 70-neutralizing IgM in animal sera

The neutralizing activity against human enterovirus type 70 was found in serum samples from normal cattle, horses, sheep, goats, swine and chickens raised in Japan. The frequency was variable depending upon animal species and the year of bleeding. The neutralizing activity in bovine sera was shown to reside in IgM by sucrose gradient centrifugation and immune gel electrophoresis. These findings suggested that the neutralizing substance in domestic animal sera is the antibody of IgM class elicited by unidentified viruses antigenically related to human enterovirus type 70.

Absence of antibodies against SV5, measles and herpes simplex in indoor colony-bred cynomolgus monkeys

One hundred and eighty-one cynomolgus monkeys born and raised at Tsukuba Primate Center for Medical Science (TPC) were serologically examined for the presence of antibodies against simian virus 5, measles virus and herpes simplex virus. All of them were virtually free from infections with these viruses, whereas wild-originated breeders kept at TPC were highly positive for these antibodies. These results can be regarded as demonstrating that an indoor breeding system such as TPC's is useful and valuable for producing nonhuman primates of good quality being completely free from those viral infections.

Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. III. Studies with animal sera from Ghana and Senegal

One hundred and thirty-nine bovine sera collected in Senegal in 1968 and 1969, before the human pandemic of acute hemorrhagic conjunctivitis (AHC), and 145 sera collected in 1977, seven years after the introduction of AHC, were tested for virus neutralizing (VN) titers against enterovirus 70 (EV70) in neutralization tests. Positive rates of VN titers (1:16) were fairly constant (about 40%) in 1968 and 1969 but the proportion of positives from the 1977 collection was significantly higher (61%). The proportion of Ghanaian bovine sera positive in 1977 (39%) was comparable with those collected earlier in Senegal but the proportion was lower in sera of calves (7%). Similar studies were performed on sheep sera collected in 1966, 1967, 1968, and 1969 in Senegal. The proportions positive and the geometric mean titers (GMTs) peaked in alternate years: the proportions were 43% and 54% in 1966 and 1968 but dropped to 12% and 5% in 1967 and 1969, respectively. The prevalence rate for Ghanaian sheep sera in 1977 was comparable to the earlier figures in Senegal. The prevalence of VN (83%) and the GMT (1:27.28) in swine sera in Ghana in 1977 were much higher than those seen in chickens and dogs. However, 87 sera of wild monkeys caught in Senegal after 1970 were negative in neutralization tests. The VN substance detected in these domestic animals was found to be 2-mercaptoethanol sensitive; hence it is considered to belong to IgM. The results seem to favor the hypothesis that enterovirus type 70 (EV70) evolved from an animal enterovirus which shares a common antigen with EV70.

Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. II. Studies with human sera collected in West African countries other than Ghana

Human sera were collected in Senegal, Nigeria, Ivory Coast, Dahomey, Liberia, Gabon and Togo during the pre-epidemic period of acute hemorrhagic conjunctivitis (AHC) from 1965 to 1969, and tested for virus neutralizing (VN) antibody to enterovirus type 70 (EV70). Of these, 1109 (91%) were antibody negative (less than equal to 1:4), 116 (9%) neutralized at a dilution of 1:8 or over, and 45 (4%) at dilutions of at least 1:16. The distribution pattern is not significantly different from that of sera collected from Kenya in 1967 or from army recruits in the United States, Argentina, Brazil and Colombia in the 1960s. Sera collected during the post-epidemic period (1970 to 1977) in Senegal, Sierra Leone, Mali, Upper Volta, Chad, Niger and Gabon were also examined; 1573 (68%) were VN antibody negative (less than or equal to 1:4), while 733 (32%) and 433 (19%) had titers of 1:8 or greater and 1:16 or over, respectively. There is a significant difference in distribution between pre- and post-epidemic antibody titers (p less than 0.001), although the incidence of AHC was lower in these countries than in Ghana and Southeast Asia. The prevalence of VN antibodies tends to be lower in the dry, hot inland areas and thus humid coastal monsoonal climates and dense populations seem to favor the spread of AHC.

Serological survey for SV5, measles and herpes simplex infections in newly-imported cynomolgus monkeys

On 592 cynomolgus monkeys of newly-imported 14 different groups, sero-epidemiological follow-up surveys of natural infections with SV5, measles (MV) and herpes simplex (HSV) were conducted both at the time of arrival and at the end of the 9-week quarantine period at Tsukuba Primate Center for Medical Science (TPC). At the time of arrival, the positive rate of antibodies against these viruses greatly varied with different countries of origin. As regards SV5, the positive rate ranged widely from 0 to 94.9% among different import-groups, being markedly low in the Philippine monkey groups. The positive rate of MV antibody was generally very high, varying from 11.1 to 78.2% in almost all import-groups except two groups from Indonesia in which no positive case was detected. Concerning HSV, every import-group had a very high positive rate though the average antibody titer was not so high. Generally, the positive rates of SV5 and MV markedly increased by the end of quarantine period. Especially, MV positive rate reached 100% in almost all of the import-groups. However, two Indonesian groups showed no increase of SV5 and MV positive rates during the quarantine period. No increase of SV5 positive rate was detected either with any of three Philippine groups. As for HSV, the positive rate remained unchanged or rather decreased during the quarantine period in almost all groups except two Indonesian groups having shown a significant increase.

Hemoagglutination and hemagglutination inhibition tests with enterovirus type 70

Human type "O," guinea pig, and chicken erythrocytes were agglutinated by enterovirus type 70 at 4 degrees C or room temperature. A hemagglutination inhibition test, using human "O" erythrocytes, is described for the serological diagnosis of acute hemorrhagic conjunctivitis caused by enterovirus type 70.

Virological and serological studies of neurological complications of acute hemorrhagic conjunctivitis in Thailand

An extensive outbreak of acute hemorrhagic conjunctivitis (AHC) occurred from September to December 1974 in Thailand. At least 29 patients with polio-like motor paralysis that complicated AHC were hospitalized in Bangkok. Paired or triplicate samples of serum from 16 patients were tested for neutralizing antibody to enterovirus type 70 (EV70). A significant rise in titer of antibody was found for two patients, and the other 14 had neutralizing antibody titers ranging from 1:8 to 1:512 without an increasf larger than or equal to 1:16, a level which is considered to be diagnostically significant. Neutralizing antibody to EV70 was detected in 19S fractions of nine sera examined, but neutralizing antibody to three types of poliovirus was confined to 7S fractions. EV70 was isolated from one of seven stool specimens collected on day 37 after the onset of AHC and none of 10 samples of cerebrospinal fluid. These results and additional clinical and epidemiologic findings gave further support to the hypothesis that EV70 infection can cause polio-like motor paralysis as a complication of AHC.

Growth characteristics of acute hemorrhagic conjunctivitis (AHC) virus in monkey kidney cells. II. Temperature sensitivity of the isolates obtained at various epidemic areas

Acute hemorrhagic conjunctivitis (AHC) virus strains isolated in eight different areas during epidemics of AHC were tested for the reproductive capacity at 33, 37 and 39 degrees. All of the 25 strains tested grew better at 33 degrees but restrictively at 39 degrees. The degree of temperature sensitivity varied slightly from one strain to the other, but generally exceeded that of attenuated poliovirus type 1, strain LSc2ab. Temperature-resistant clones were selected by repeated passages of originally temperature-sensitive prototype strains at supraoptimal temperature. The importance of using a low temperature (32-34 degrees) for isolation of virus from external tissues of the body and for subsequent passages has been emphasized. It was suggested that the relatively low temperature of the conjunctiva has played a role in perpetuating temperature sensitivity of this virus.

Serologic characterization and sero-epidemiologic studies on acute hemorrhagic conjunctivitis (AHC) virus

Serologic and sero-epidemiologic characteristics of AHC virus infection were studied by neutralization test (NT). Four-fold or greater virus neutralizing (VN) antibody response was demonstrated to the Japanese isolate of AHC virus (the J 670/71 strain) in 77.3% and 66.7% of paired sera from clinical AHC patients in Japan (1971-1973) and Tunisia (1973). The four patients from Indonesia studied in 1972 showed similar antibody response. Cross-neutralization tests of AHC virus isolated in Japan (1971), Taiwan (1971), Hong Kong (1971), Thailand (1972), Indonesia (1972), Singapore (1972), Morocco (1971) and England (1971) with three kinds of antisera prepared against Japanese, Hong Kong and Moroccan AHC virus isolates indicated their antigenic identity. However, isolates from Sinapore in 1970 (Singapore 70 virus) were not neutralized with the AHC virus antisera mentioned above: Singapore 70 virus constitutes another antigenic type, to which, however, no VN antibody rise was found in paired patients' sera from Japan, Tunisia and Indonesia. Thus, no serologic evidence supporting an etiologic role of this virus group in the development of AHC was found. Although cross-tests using monospecific antisera suggested some cross-relation between AHC and both echovirus type 4 (E4) and coxsackie A (CA), type 19, no serologic relationship between AHC and these viruses was found. Sera from healthy individuals collected before and after AHC outbreaks were tested for VN antibody against AHC virus in Japan and two epidemic foci, Ghana and Indonesia. Before the epidemic, 80 to 90% of the people lacked antibody in the three countries, but 39.7% and 45.2% of inhabitants posessed VN antibody of 1:8 or over in Ghana and Indonesia after the outbreak. In Japan, however, only a slight increase was found in VN antibody prevalence afterwards. Serologic study showed that 41.5% of horse sera were VN positive at dilutions of 1:8 or more; many cattle sera also had a low VN titer but few cynomologus monkey sera had VN activity.