Biomedical subjects
Nobuko Yamashita
Publications and source records attributed to Nobuko Yamashita.
Virological aspects of Epstein-Barr virus infections.
Epstein-Barr virus (EBV) is usually maintained in an asymptomatic and latent form by the host immune system, and primarily by EBV-specific cytotoxic T cells (CTLs). However, EBV has been linked to several refractory diseases such as EBV-associated hemophagocytic syndrome(EBV-AHS) and chronic active EBV infection (CAEBV). In these ectopic diseases, EBV infects T/NK cells, causing severe immunodeficiency with a very high EBV load. In recent years, the laboratory procedure to assess these types of EBV infections has been improved. In particular, real-time polymerase chain reaction (PCR) has been used to quantify the EBV load, and the MHC: peptide tetramer assay has been used to quantitate EBV-specific CTLs; these tests have been employed for the management of the illnesses associated with EBV infection. Here, we have reviewed the recent progress in the clinical application of these assays. The pathogenesis of EBV-infected T/NK cells, and the host immune response to infection, including the roles carried out by innate immunity and inflammatory cytokines, are likely to be revealed in the future.
HHV-6 and seizures.
Human herpes virus-6 (HHV-6) is a ubiquitous virus, but one that can induce various neurological diseases. Recently, several seizures have been reported as new HHV-6-associated diseases based on virological analysis. Neonates who are perinatally infected with HHV-6 can develop afebrile seizures, which are considered to be exanthem subitum (ES) in the neonatal period. Infants with ES also tend to develop atypical febrile seizures. After primary infection, HHV-6 commonly establishes latency in the central nervous system (CNS) and sometimes reactivates in the hippocampus, causing limbic encephalitis and temporal lobe epilepsy. These HHV-6-associated CNS diseases due to virus reactivation can occur in both immunocompromised and immunocompetent hosts. This article summarizes HHV-6-associated seizures during childhood.
[Unruptured cerebral aneurysms; the features of cases undetected with MR angiography].
With the development of MRI and MRA, many unruptured aneurysms have been detected and treated. Nevertheless, not a few false-positive and false-negative cases are found. We investigate aneurysms that were suspected after screening MRA at the neurosurgical outpatient clinic and the features of aneurysms detected not with MRA but with DSA were studied. Seventy-six patients (85 aneurysms) were suspected due to screening MRA and DSA was performed in 64 (71 aneurysms) of them. Correct diagnosis of cerebral aneurysms with MRA was obtained in 44 patients (45 aneurysms, 63.4%), while false-negative cases were found in 17 patients (plus 20 aneurysms) and false-positive cases in 7 patients (10 aneurysms). The accuracy was 97.2% in ACA, 93% in MCA, 94.4% in VA-BA, and 78.9% in IC, while the sensitivity 100%, 88.2%, 81.8%, 64.7% and the specificity 96.5%, 94.4%, 96.7%, 91.9%, respectively. The features of aneurysms correctly diagnosed with MRA were relatively large ACA, including AcoA, MCA and VA-BA aneurysms, whereas the features of aneurysms undetected with MRA were small IC aneurysms (1-3mm in diameter), especially at the C2-3 portion. These aneurysms at the C2-3 portion or at unusual portions tended to be difficult to detect even with 3D-CTA. Though most of the aneurysms detected with DSA but not with MRA tended to be small and not interventionally treated in the present study, we should pay attention to the fact that these aneurysms are overlooked despite the possibility that they may become enlarged or rupture. Though ruptured aneurysms were surgically treated with only MRA or 3D-CTA without conventional angiography in these days, we recommend the examination of the unruptured cases, which are usually asymptomatic and not hasty, with precise inspection by target MIP, high-performance 3D-CTA or DSA.
Analysis of linear growth in survivors of childhood acute lymphoblastic leukemia.
Therapy for childhood acute lymphoblastic leukemia (ALL) is entering a new era in terms of quality-of-life. In the current study, 21 patients with childhood-onset ALL were assessed for linear growth, bone mineral density (BMD), and endocrinological status, focusing especially on longitudinal analysis of the growth of each patient. Linear growth was uniformly attenuated during therapy in all patients. In contrast, after the cessation of therapy, the growth of each patient varied widely from attenuated to dramatic catch-up growth. In pubertal survivors who had received chemotherapy and cranial irradiation during prepuberty, the degree of growth after the cessation of therapy was negatively correlated with changes in height Z scores during therapy ( r = -0.76, P= 0.004). One of the factors involved in catch-up growth, urinary N-telopeptide/creatinine (U-NTx/Cr), was significantly higher in patients whose Z scores decreased after cessation of therapy ( P = 0.01), despite normal pubertal development and normal endocrinological assessments. The present study revealed individual differences in linear growth after the cessation of therapy and suggests the importance of catch-up growth during puberty.
Clinical evaluation of shunt implantations using Sophy programmable pressure valves: comparison with Codman-Hakim programmable valves.
We describe our experience with Sophy programmable valve shunts, compared with Codman-Hakim programmable shunts in cases with normal pressure hydrocephalus (NPH) after subarachnoid hemorrhage (SAH). A total of 147 consecutive patients underwent 204 shunt implantations (102 Sophy valves, 51 Codman-Hakim valves, 51 nonprogrammable valves). Of these, 23 Sophy and 25 Codman-Hakim valves respectively were implanted into patients with NPH after SAH. Comparison of reprogramming rate and frequency in cases with NPH after SAH between Sophy and Codman-Hakim valves revealed similar reprogramming rates (65.2 vs. 64.0%) but a higher frequency with the former (1.70 vs. 1.08 times/person). The mean difference between initial and final pressure was 65.3+/-45.8mmH(2)O in cases with Sophy valves, and 25.0+/-14.1mmH(2)O with Codman-Hakim valves. The average period which was required to determine the final pressures with Sophy and Codman-Hakim valves were 56.5+/-45.0 days and 43.3+/-45.7 days, respectively. Total incidence of complications of Sophy and Codman-Hakim valve shunt systems in cases with NPH after SAH were 26.1% (6/23) and 16% (4/25), respectively. Total instances requiring shunt revision with Sophy valves in cases of NPH after SAH were 6 of 23 (26.1%), while for Codman-Hakim valves the figure was 2 of 25 (8.0%). Sophy, as well as Codman-Hakim programmable valve shunts, allow alteration of opening pressure after the implantation according to patients' conditions, which may contribute to reduction of revision. Similar reprogramming rates but lower frequency, and smaller difference between initial and final pressure in Codman-Hakim valves may be ascribed to finer pressure ranges and ease of reprogramming, which facilitates earlier reprogramming and decisions regarding final optimal opening pressure.
Comparison of thallium-201 uptake and retention indices for evaluation of brain lesions with SPECT.
Thallium-201 chloride single photon emission computed tomography ((201)TlCl SPECT) has been applied extensively for studies of human tumors. To assess which indices for (201)TlCl SPECT are most useful for diagnosing brain lesions, a total of 82 patients (98 images) with intracranial abnormalities were investigated. Seventy-six cases with abnormal (201)Tl uptake were evaluated in terms of six different (201)Tl uptake and retention indices: (1) average early (201)Tl uptake = Av.Le/Av.Be; (2) maximum early (201)Tl uptake = Mx.Le/Av.Be; (3)(201) Tl retention A = Av.Ld/Av.Le; (4) (201)Tl retention B = Mx.Ld/Mx.Le; (5) (201)Tl retention C = (Av.Ld/Av.Bd)/(Av.Le/Av.Be); (6) (201)Tl retention D = (Mx.Ld/Av.Bd)/(Mx.Le/Av.Be), where Av.Le and Mx.Le are average and maximum early counts for lesions, Av.Be and Av.Bd are average early and delayed counts for contralateral normal brains, and Av.Ld and Mx.Ld are average and maximum delayed counts for lesions. Comparison of patients with benign and malignant lesions did not demonstrate significant differences with any of the indices. However, low (I-II) and high (III-IV) grade astrocytomas varied in their average and maximum early (201)Tl uptake indices (both P = 0.0026). For patients with and without meningiomas, P values for indices of maximum early(201) Tl uptake and (201)Tl retention A and B were 0.0338, 0.0005, 0.0002, respectively. While comparison of patients with metastatic brain tumors and gliomas again showed no significant differences between the groups, the presence or absence of calcification was associated with significant variation in all the indices. With (201)TlCl-SPECT imaging, the average and maximum early (201)Tl uptake indices are appropriate for the assessment of tumor viability or malignancy, while (201)Tl retention indices (A,B) are useful for tumor differentiation, especially with meningiomas. Choice of suitable indices should enhance the utility of (201)TlCl-SPECT imaging in pre- and postoperative evaluation of intracranial lesions.
Infantile renal dysfunction associated with intrauterine exposure to ritodrine and magnesium sulfate.
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