Seropositivity and epidemiology of human parechovirus types 1, 3, and 6 in Japan

Human parechoviruses (HPeVs) mainly infect young children, causing mild gastrointestinal and respiratory diseases; however, HPeV type 3 (HPeV3) causes severe systemic diseases in young infants. To clarify the characteristics of HPeV infections from the aspects of seropositivity and epidemiology, we measured neutralizing antibody titres against HPeVs in individuals of in different age groups and isolated HPeVs from various clinical specimens in Niigata, Japan. The seropositivity to HPeV1, 3, and 6 was higher in older age group. HPeV1 and HPeV6 seropositivities were maintained in adults, whereas HPeV3 seropositivity was significantly lower in subjects aged >40 years (P < 0·001, P = 0·003). This result suggests that adults have increased susceptibility to HPeV3 as they lack neutralizing antibodies against HPeV3. Of the HPeV isolates, HPeV1 and HPeV6 frequently caused gastrointestinal symptoms. Moreover, gastroenteritis patients with HPeV1 and HPeV6 were mainly aged 6 months-1 year and ⩾2 years, respectively. In contrast, only HPeV3 was isolated from neonates and young infants with sepsis or sepsis-like syndrome, often with respiratory symptoms. These results suggest that clinical symptoms are clinically related to HPeV genotype and patients' age.

APPLICATION OF THE STEREOSPECIFIC INHIBITOR L-PHENYLALANINE TO THE ENZYMORPHOLOGY OF INTESTINAL ALKALINE PHOSPHATASE

The intestine-specific inhibitor of alkaline phosphatase, l-phenylalanine, has been employed in the study of alkaline phosphatase in rat intestine. Five substrates were used, β-glycerophosphate, o-carboxyphenylphosphate, α-naphthyl acid phosphate, naphthol AS-BI phosphate and naphthol AS-TR phosphate. The hydrolytic rate and specific l-phenylalanine inhibition was most marked in the case of the first three substrates. When formol-Ca fixed, gum-sucrose treated sections of rat intestine were incubated in these substrates in the presence separately of 0.05 Md- and l-phenylalanine and Gomori's calcium-cobalt method was employed, a striking inhibition by the l-isomer was regularly found. Azo dye methods were applied under different conditions of time, temperature and cation concentration in some instances. The contrast was marked but not dramatic in the case of α-naphthyl acid phosphate, and it was evident but not marked in the case of naphthol AS phosphate substrates. These findings have been discussed.

The alkaline phosphatase of intestinal epithelial cells (human) grown in tissue culture exhibited great sensitivity to l-phenylalanine. Rat kidney and leukocyte alkaline phosphatase were relatively insensitive under the same conditions.

Morphologically, the l-phenylalanine-sensitive alkaline phosphatase in rat intestine is largely confined to the striated border of the epithelial cells. In animals maintained on a high fat diet, azo dye methods demonstrated the presence of fine granules in the region of the Golgi apparatus and terminal web in the presence of d-phenylalanine. These reactions were absent in companion sections incubated in l-phenylalanine-containing substrate solutions.

The possibility of comparing the morphology of a tissue in which both test and control solutions are identical except for the configuration of one component may contribute to a more precise interpretation of the results obtained in the test section.

CHANGES IN HYDROLASE ENZYMORPHOLOGY OF RAT UTERUS AND VAGINA AFTER ESTROGENS; NAPHTHOL AS SUBSTRATES

The early enzymorphologic changes of rat uterus and vagina on castration and following estrogen administration (estradiol-17β, estrone and estriol) were examined with regard to alkaline phosphatase, esterase, β-glucuronidase and acid phosphatase using naphthol AS compounds as substrates.

Castration caused a marked decrease of enzyme activities except for alkaline phosphatase of capillary endothelium and for nonspecific esterase.

All activities, compared to castrated controls, were markedly increased by estrogen administration except for the alkaline phosphatase of capillary endothelia. Estriol and estrone were more potent than estradiol-17β in the early stage of estrogen treatment (4-hour interval).

The response of alkaline phosphatase of striated border of lumenal uterine epithelium to estrogen treatment is unique in that the other hydrolases were absent from this site.

The estrogen sensitivity of the hydrolases of connective tissue cells of rat uterine stroma is clearly evident for the first time.

Of interest also is a comparison of β-glucuronidase and acid phosphatase in which naphthol AS-BI is the product of enzyme hydrolysis in each case. Although the intensity of the respective staining reactions correlated well with each other in relation to the events of castration and estrogen administration, there were clear differences evident.

Finally, the new findings demonstrate the value of the improved techniques as well as resolve some ambiguities of earlier findings obtained with diverse methods.

Short report: antimicrobial susceptibility and genetic characteristics of Haemophilus influenzae isolated from patients with respiratory tract infections between 1987 and 2000, including beta-lactamase-negative ampicillin-resistant strains

The minimum inhibitory concentration (MIC) of five antibiotics and the presence of resistance genes was determined in 163 Haemophilus influenzae isolates collected over 13 years (1987-2000) in four two-yearly sampling periods from patients with respiratory tract infections. The prevalence of beta-lactamase-negative ampicillin-susceptible strains was approximately 80% over the sampling period although fewer strains (65.9%) were recovered in the period 1995-1997. TEM-1 type beta-lactamase-producing strains were less frequent starting at 15.6% and declining to 2.2% in the final sampling period. Low-beta-lactamase-negative ampicillin-resistant (BLNAR) strains were uncommon in 1987-1989 (2.2%), peaked to 19.5% in 1995-1997, but fell back to 11.1% by 2000. Fully BLNAR strains were not detected until the last sampling period (6.7%). The MICs of ampicillin, levofloxacin, cefditoren and ceftriaxone remained stable but there was an eight-fold increase in the MIC of cefdinir over the sampling period. Pulsed-field gel electrophoresis of DNA digests showed that three representative BLNAR strains were genetically distinct and 11 DNA profiles were identified among 17 low-BLNAR strains. These data suggest that the number of genetically altered BLNAR and low-BLNAR strains are increasing in Japan.

Antimicrobial susceptibility and serotype distribution of Streptococcus pneumoniae isolated from patients with community-acquired pneumonia and molecular analysis of multidrug-resistant serotype 19F and 23F strains in Japan

A nationwide study was undertaken to determine the susceptibility to penicillin and serotypes of Streptococcus pneumoniae in Japan. S. pneumoniae was isolated from 114 adult patients with community-acquired pneumonia over 22 months at 20 hospitals and medical centres in different regions in Japan. All but five isolates were from sputum. Forty-eight isolates (42.1%) were susceptible, 40 (35.1%) showed intermediate resistance (MIC, 0.12-1.0 microg/ml) and 26 (22.8%) were resistant (MIC, >or=2.0 microg/ml) to penicillin G. All isolates were susceptible to ceftriaxone (breakpoint 1 microg/ml), imipenem (4 microg/ml) and vancomycin (4 microg/ml). Most were resistant to erythromycin, clarithromycin and azithromycin; only two were resistant to levofloxacin. Differences were found in the distribution of serotypes among isolates showing susceptibility to penicillin (predominant types 3, 6B, and 19F), intermediate resistance (6B, 14, 19F, and 23F) and full resistance (19F and 23F). PFGE typing showed that 14 of the 25 strains of serotype 19F had a single DNA profile, pattern A, a pattern closely similar to that of the Taiwan multidrug-resistant 19F clone. Twelve pattern A strains were not susceptible to penicillin but carried the macrolide resistance gene mef(A). The DNA profiles of the 15 strains of 23F were also heterogeneous but six were highly similar (pattern b) yet distinct from the Spanish multidrug-resistant 23F clone although possibly related to the Taiwan multidrug-resistant 23F clone. The pattern b strains were not susceptible to penicillin and also harboured either mef(A) or erm(B). Our results indicate that multidrug-resistant pneumococci are spreading rapidly in Japan. Efforts to prevent the spread of the pandemic multidrug-resistant serotypes should be intensified.

Plateau-Generating Nerve Cells in Helix: Properties of the Repolarizing Voltage-Gated and Ca2+-Activated Potassium Currents

The aim of this study was to identify and characterize the repolarizing currents present in Helix nerve cells that generate long-lasting Ca2+-dependent depolarized plateaus in response to low-frequency stimulation. Two K+ currents were identified: a voltage-gated K(V) current and a Ca2+-activated K+ current or C current. These currents were studied separately in cells injected with either EGTA, tetraethylammonium (TEA+) or Cs+. C current activation was found to be rate-limited by the size of the inward Ca2+ current. Both K(V) and C currents displayed a pronounced relaxation during sustained depolarizations. Inactivation of the K(V) current was voltage-dependent. Inactivation of the C current was induced by either tiny Ca2+ entries or intracellular Ca2+ injections; C current inactivation was found to be more sensitive to intracellular [Ca2+] than the activating process. Similar experiments performed on various nerve cells revealed that the amount and rate of inactivation of both currents, but not their gating properties, varied greatly from cell to cell; plateau-generating cells had the strongest inactivating processes acting on both K+ currents. These properties help to explain how regular firing may turn into long-lasting depolarized plateaus. They point to the existence of cellular processes that might regulate the number of available K+ channels in a manner that is specific to the nerve cell type.

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