Koichi Baba

Human Herpesvirus 6 Infection In Renal Transplantation

The relationship between renal transplantation and human herpesvirus 6 (HHV-6) infection was studied. All 21 kidney donors examined had antibody to HHV-6 at the time of transplantation. The 21 kidney recipients also had detectable antibody to HHV-6 before transplantation--and, of these, 8 patients showed a significant increase of serum antibody titer against HHV-6 after transplantation. All these 8 recipients suffered severe kidney rejection. Furthermore, virus isolation from peripheral blood lymphocytes of 2 recipients who suffered rejection was attempted, and in both cases HHV-6 was isolated. Biopsy specimens of rejected kidneys of 9 other patients were examined for the presence of HHV-6 antigens, and in 5 of these specimens antigens were detected in the tubular epithelium, as well as in infiltrating histiocytes and lymphocytes. These results suggest that HHV-6 can infect renal tissues and that the infection may be correlated with rejection or with immunosuppressive therapy.

Increased incidence of herpes zoster in normal children infected with varicella zoster virus during infancy: Community-based follow-up study

We surveyed outbreaks of varicella zoster virus (VZV) and herpes zoster virus, involving 31 outbreaks of chicken pox, in a semiclosed institution in Osaka Japan during the 34 years between 1949 and 1984. Eight hundred forty-nine infants and children who had had clinical varicella during the first 4 years of life and those who had resided in the institution at least 12 to 144 months after the onset of varicella were included in the study. Nine cases of zoster were observed among children who had acquired varicella during the first year of life, but there was no case of zoster in those who had acquired varicella after 1 year of age. In 61,800 person-months of observation, the overall incidence rate of zoster was calculated as 0.15 per 1000 person-months for the population at risk. The incidence rate in children infected with VZV when younger than 2 months was 1.0 per 1000 person-months during the first decade of life. This rate was significantly (P less than 0.005) greater than that (0.19 per 1000 person-months) in children who had varicella when they were 2 to 11 months of age. These observations suggest that zoster occurs at a significantly shorter interval if VZV infection is acquired during infancy. More than 85% of subjects with prior infection were intimately reexposed to epidemic varicella during their residency in the institution, before having zoster. Epidemic reexposure to varicella during follow-up resulted in enhancement of preexisting immunologic reactivity, but did not prevent subsequent zoster in the population studied.

A Kv4.2 truncation mutation in a patient with temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) has a multifactorial etiology involving developmental, environmental, and genetic components. Here, we report a voltage-gated potassium channel gene mutation found in a TLE patient, namely a Kv4.2 truncation mutation. Kv4.2 channels, encoded by the KCND2 gene, mediate A currents in the brain. The identified mutation corresponds to an N587fsX1 amino acid change, predicted to produce a truncated Kv4.2 protein lacking the last 44 amino acids in the carboxyl terminal. Electrophysiological analysis indicates attenuated K+ current density in cells expressing this Kv4.2-N587fsX1 mutant channel, which is consistent with a model of aberrant neuronal excitability characteristic of TLE. Our observations, together with other lines of evidence, raise the intriguing possibility of a role for KCND2 in the etiology of TLE.

Ion irradiation effects on ionic liquids interfaced with rf discharge plasmas

The availability of plasma ion irradiation toward a gas-liquid interface is investigated in a rf discharge system incorporating an ionic liquid. The introduction of the ionic liquid to the plasma causes the formation of a sheath electric field on the ionic liquid surface, resulting in the acceleration of the ions to the ionic liquid and the generation of secondary electrons from the ionic liquid by the ion irradiation. These effects are found to advance the discharge process and enhance the plasma production.

Immunologic and epidemiologic aspects of varicella infection acquired during infancy and early childhood.

The development of varicella zoster infection was studied in a population of infants under one year of age during three outbreaks of varicella in a semi-closed domiciliary institution for infants in Japan. Over a period of four years, many residents ranging in age from 27 days to 32 months were tested for cutaneous reactivity to VZV antigen, and VZV-specific antibody activity before, during, and after each outbreak of varicella. Of these, 85 subjects developed clinical varicella, with an overall attack rate of 100% for all susceptible subjects. All the infants under 2 months of age were infected following such exposure, despite the presence of pre-existing maternal antibody. The degree of cutaneous involvement appeared to be milder (less than 20 vesicles) in infants less than 2 months of age, and severe cutaneous disease (with over 300 eruptions or confluent rash) occurred more frequently in subjects 2 to 11 months of age. Pre-existing antibody did not prevent development of illness, or alter the degree of antibody or cellular immune response to subsequent infection. However, the peak cutaneous reactivity to VZV antigen after infection was found to be significantly lower in infants under 2 months of age.

A method for enhancing the ocular penetration of eye drops using nanoparticles of hydrolyzable dye.

This report describes a method for enhancing the ocular penetration of eye drops using nanoparticles of hydrolyzable dye, which is similar to a prodrug approach. The entry of eye drops into the ocular globe is restricted predominantly by corneal barrier functions. The barrier functions are epithelial tight junctions as well as a physicochemical property consisting of the opposite characteristics of a lipophilic epithelium and a hydrophilic stroma. We found that using a formulation of nanoparticles of hydrolyzable dye (with particles of 200 nm in diameter on average) attained a greater than tenfold higher (about 50-fold) ocular penetration than that of micron-sized particles. The nanoparticles were prepared by a carrier-free technique; i.e., the reprecipitation method. Confocal laser fluorescence microscopy showed that dyes originating from the nanoparticles surmounted the corneal epithelium barrier, which has tight junctions, and achieved deeper penetration into the cornea. The high penetration rate of the dyes into the cornea was attributed to the size of particles (i.e., nanoparticles) and a transformation of dye polarity from lipophilic to hydrophilic in in vivo hydrolysis reactions. We concluded that utilizing in vivo hydrolysis reactions to alter the physicochemical nature of nanoparticles consisting of hydrolyzable compounds was an effective approach for enhancing the ocular penetration of eye drops.

Neuroradiologic Findings in Focal Cortical Dysplasia: Histologic Correlation with Surgically Resected Specimens

Summary:  Purpose: We investigated the neuroradiologic characteristics of focal findings of surgically resected specimens obtained from 47 patients with focal cortical dysplasia (FCD).

Fabrication of organic nanocrystals using microwave irradiation and their optical properties

1,1,4,4-Tetraphenyl-1,3-butadiene nanocrysytals were fabricated by the microwave method, whose procedure is the conventional reprecipitation followed by the microwave irradiation. Using this method, monodispersive nanocrystals possessing the crystal structure different from that of bulk crystals were produced. Change in optical properties depending on the crystal size is also reported.

Static gas-liquid interfacial direct current discharge plasmas using ionic liquid cathode

Due to the unique properties of ionic liquids such as their extremely low vapor pressure and high heat capacity, we have succeeded in creating the static and stable gas (plasmas)-liquid (ionic liquids) interfacial field using a direct current discharge under a low gas pressure condition. It is clarified that the ionic liquid works as a nonmetal liquid electrode, and furthermore, a secondary electron emission coefficient of the ionic liquid is larger than that of conventional metal electrodes. The plasma potential structure of the gas-liquid interfacial region, and resultant interactions between the plasma and the ionic liquid are revealed by changing a polarity of the electrode in the ionic liquid. By utilizing the ionic liquid as a cathode electrode, the positive ions in the plasma region are found to be irradiated to the ionic liquid. This ion irradiation causes physical and chemical reactions at the gas-liquid interfacial region without the vaporization of the ionic liquid.

Novel Fabrication Process of Organic Microcrystals Using Microwave-Irradiation

The reprecipitation method is a useful technique for the fabrication of organic microcrystals. We have further developed this method for the preparation of some well-defined and monodispersed organic microcrystals by utilizing microwave irradiation.