Prenatal ultrasonographic appearance of type IIId (uncorrectable type with cystic dilatation) biliary atresia

Although prenatal ultrasonographic (US) diagnosis has been reported in biliary atresia (BA), most cases are type I (correctable with cystic dilatation). We report three prenatal cases of type IIId BA (uncorrectable with cystic dilatation). Routine fetal US at 22 to 24 weeks of gestation showed two communicating cystic lesions 12 to 16 mm in diameter. On color Doppler US, the lesions were separate from the portal vein or hepatic artery. The size did not change during the prenatal period in any case. Choledochal cyst (CC) was considered the most likely diagnosis, although BA with cystic lesions was also considered. After birth, the patients developed acholic stools and prolonged neonatal jaundice. Hepatobiliary scintigraphy showed negative passage. Duodenal fluid showed a negative or slightly positive Gmelin test. The neonates underwent laparotomy at the age of 36, 46, and 32 days, respectively. Intraoperative cholangiography showed the gallbladder and slightly-dilated common-bile duct without entering the proximal or distal bile ducts in all cases. They were classified as type IIId BA and underwent excision of the cystic lesions and dissection of the portal bile-duct remnants, followed by hepatic portoenterostomy. Case 1 showed persistent jaundice and finally underwent liver transplantation (LTx), case 2 became anicteric. Case 3 remained jaundiced and is to undergo LTx. In conclusion, type IIId BA may be one of the differential diagnoses when a cystic lesion is detected under the hepatic hilum by fetal US. However, prenatal diagnosis of BA is still difficult with respect to differentiation from a CC or type I BA. Early postnatal diagnosis followed by immediate treatment is important, especially in type IIId BA.

Semiquantitative analysis of corpus callosum injury using magnetic resonance imaging indicates clinical severity in patients with diffuse axonal injury

OBJECTIVE

To evaluate the hypothesis that the extent of corpus callosum injury indicates the depth of shearing lesions in the central brain structure and therefore relates to the clinical severity of diffuse axonal injury.

METHODS

A simple and objective procedure for semiquantitative analysis of magnetic resonance images (MRI)-the maximum signal intensity ratio (MSIR)-was employed prospectively in 21 patients with diffuse axonal injury but without apparent injury to the ventral pons. All were diagnosed using serial combination MRI scans of fluid attenuated inversion recovery (FLAIR) and T2* weighted gradient echo imaging during the initial two weeks after the injury. The signal intensity ratio between the two regions of interest-the corpus callosum and the normal appearing ventral pons-was calculated serially in mid-sagittal and parasagittal FLAIR image sections in each patient. The MSIR during the study period was determined as a semiquantitative index of corpus callosum injury in each patient. The correlations between MSIR and the duration of unconsciousness, Glasgow outcome scale at six months, and the presence of apparent midbrain injury were investigated.

RESULTS

The mean (SD) MSIR value was 1.12 (0.18) at 7.4 (3.1) days after the injury (n = 21). MSIR correlated strongly with the duration of unconsciousness (n = 19, R(2) = 0.74, p < 0.0001), and was higher in patients with both an unfavourable GOS outcome (p = 0.020) and apparent midbrain injury (p < 0.001).

CONCLUSIONS

MSIR, which is a simple and objective procedure for semiquantitative analysis of corpus callosum damage in diffuse axonal injury, correlated with clinical severity. A high MSIR value may indicate the presence of concomitant midbrain injury.

Mechanisms responsible for recurrent gastroesophageal reflux in neurologically impaired children who underwent laparoscopic Nissen fundoplication

BACKGROUND

In this study, we attempted to define the lower esophageal sphincter (LES) motor events associated with the occurrence of gastroesophageal reflux (GER) in neurologically impaired children in whom of GER disease recurred after laparoscopic Nissen fundoplication (LNF).

METHODS

Of 45 neurologically impaired children who had previously undergone LNF, six children in whom recurrence of GER disease was documented by 24-h esophageal pH monitoring were studied. Concurrent esophageal manometry and pH monitoring were conducted for 1 h both before and after the administration of apple juice (10 ml/kg).

RESULTS

A total of 89 reflux episodes were recorded in the course of the study. Of these, 51 episodes (57%) were associated with transient LES relaxation. In the remainder, reflux occurred across a contracted LES in 21 episodes (24%) and during absent basal LES tone in 15 episodes (17%). In four of six patients, transient LES relaxation was responsible for more than half of the reflux episodes.

CONCLUSION

Transient LES relaxation is the predominant mechanism of reflux in neurologically impaired children with recurrent GER after LNF.

Measurement of serum total bile acid levels in long-term postoperative follow-up of patients with congenital bile-duct dilatation

Serum total bile acid levels (STBA), a sensitive indicator of cholestasis, were measured during the long-term postoperative period in patients with congenital bile-duct dilatation (CBDD) (choledochal cyst) and the factors contributing to elevation of STBA were analyzed in 44 patients. Their ages at operation ranged from 1 month to 16 years. A STBA level over 12 nmol/ml on two or more measurements during outpatient follow-up was considered abnormal. Patients were classified into three groups: group 1, STBA, 12-50 nmol/ml; group 2, STBA > or = 50 nmol/ml; group N, STBA normal. In 19 patients (43.2%) STBA was normal. Of the 25 patients (56.8%) with elevated STBA, groups 1 and 2 comprised 12 (27.3%) and 13 patients (29.5%), respectively. The mean age in group N was 5.1 +/- 4.2 years, which was higher than in groups 1 (2.6 +/- 2.3) and 2 (2.3 +/- 2.5 years) ( P< 0.05). Preoperative STBA and total bilirubin were higher in group 2 (79.2 +/- 75.1 nmol/ml resp. 5.2 +/- 4.2 mg/dl) than in groups N (20.1 +/- 32.6, 1.3 +/- 1.4) and 1 (22.8 +/- 37.2, 1.4 +/- 1.0) ( P< 0.05). Preoperative alkaline phosphatase and gamma-glutamyl transpeptidase were higher in group 2 (1,006 +/- 872 IU/l, 452 +/- 326 IU/l) than in group N (573 +/- 371, 205 +/- 238) ( P< 0.05). Histologic findings on liver biopsy showed fibrosis in 38.5% of group 2 patients, which was significantly higher than in groups N (15.8%) and 1 (16.7%) ( P< 0.05). Cholestasis was detected in 41.7% of group 1 and 61.5% of group 2 patients, compared to 10.5% of group N patients ( P< 0.05). Postoperative elevation of STBA may thus persist in more than one-half of patients with CBDD, and is likely to occur in patients of young age who have severe cholestasis or liver fibrosis preoperatively. Further investigations may be required in regard to the development of postoperative complications.

Experience with International Neuroblastoma Staging System and Pathology Classification

The International Neuroblastoma Staging System and Pathology Classification were proposed in 1988 and in 1999, respectively, but their clinical value has not yet been fully studied in new patients. Six hundred and forty-four patients with neuroblastoma treated between January 1995 and December 1999 were analysed by these classifications. The 4-year overall survival rate of patients <12 months of age with INSS stages 1, 2A, 2B, 3 and 4S disease was 98.5%, which was significantly higher than the 73.1% rate in stage 4 patients <12 months (P<0.0001). When patients were > or = 12 months, the 4-year overall survival rate of patients with neuroblastoma at 1, 2A, 2B and 3 stages was 100% and that of patients at stage 4 was 48.5% (P<0.0001). As to the International Neuroblastoma Pathology Classification histology, the 4-year overall survival rate was 98.8% in patients with favourable histology and 60.7% in those with unfavourable histology in the <12 months group (P<0.0001). In the > or = 12 months group, the 4-year oral survival of patients with favourable histology was 95.3% and that of patients with unfavourable histology was 50.6% (P<0.0001). Among biological factors, MYCN amplification, DNA diploidy and 1p deletions were significantly associated with poor prognosis in patients <12 months, as were MYCN amplification and DNA diploidy in patients > or = 12 months of age. Multivariate analysis showed that the INSS stage (stage 4 vs other stages) and International Neuroblastoma Pathology Classification histology (unfavourable vs favourable) were significantly and independently associated with the survival of patients undergoing treatment, stratified by age, stage and MYCN amplification (P=0.0002 and P=0.0051, respectively).

Changes in ontogenetic expression of estrogen receptor alpha and not of estrogen receptor beta in the female rat reproductive tract

To evaluate ontogenetic expression and localization of estrogen receptor (ER) alpha and beta in fetal female rat reproductive tract, competitive RT-PCR and immunohistochemistry were performed. Expression levels for Müllerian ERalpha, ERbeta1 and ERbeta2 mRNAs were determined by competitive RT-PCR. ERalpha expression on gestational day (GD) 15 x 5 increased 4 x 4-fold by GD 21 x 5, whereas both ERbeta1 and ERbeta2 gene expression were maintained at lower constant levels compared with ERalpha during development. ER immunolocalization was evaluated within three regions along the Müllerian duct axis; these were proximal, middle and caudal, which differentiate into oviduct, uterus and upper vagina respectively. Nuclear ERalpha was localized predominantly in proximal Müllerian epithelium, and middle and caudal Müllerian mesenchyme on GDs 15 x 5-21 x 5. Staining intensity for ERalpha increased with development in all regions. However, ERbeta immunoreactivity was not detected in any region during prenatal life after separate staining with three different polyclonal anti-rat ERbeta antibodies. These findings provide fundamental information critical for clarifying the species-specific physiological roles of ER subtypes during fetal development and for investigating the tissue-specific mechanisms underlying the prenatal response to estrogen and estrogen receptor agonists.

Identification of cis-acting promoter elements that support expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) in v-src transformed Madin-Darby canine kidney cells

Membrane-type 1 matrix metalloproteinase (MT1-MMP) expressed in tumor cells is believed to be important for the pericellular degradation of extracellular matrices during invasion and metastasis. To analyze the mechanism by which MT1-MMP becomes expressed in cancer cells, we assessed the MT1-MMP promoter region for the presence of cis-acting promoter elements that support transcription in transformed cells. Our tumor model consisted of Madin-Darby canine kidney (MDCK) cells transformed by v-src (src4 cells). MT1-MMP mRNA was only faintly detected in parental cells but was strongly expressed in the src4 cells. In parallel, src4 cells invaded into collagen gels, whereas MDCK cells did not. When MDCK and src4 cells were transiently transfected with a plasmid containing of -3000 to -99 nt from the upstream region of the MT1-MMP gene, the promoter activity was 2.6-fold higher in src4 cells than in MDCK cells. Furthermore, the region between -399 and -356 nt was found to contain the src4-specific enhancer element(s). Tandem Sp1 binding sites were also found to be essential in promoting transcription. An Egr-1 site that partially overlaps with the Sp1 sites was found to cooperate with the src4-specific enhancer and to also contribute weakly to the basal promoter activity. The presence of transcription factors that bind to the src4-specific enhancer site was detected by mobility-shift assays in src4 cell nuclear extracts but only weakly in MDCK extracts. Thus, we have identified a novel enhancer element that acts specifically in the transformed cells to enhance MT1-MMP expression.

Successful laparoscopic fundoplication in children with ventriculoperitoneal shunts

We reported successful laparoscopic fundoplication in 2 pediatric cases with VPS and discuss the safety and feasibility of the procedure. Case 1: A 13-year-old girl with VPS underwent laparoscopic fundoplication. Case 2: a 9-year-old boy with VPS underwent laparoscopic fundoplication. In both cases, laparoscopic Nissen fundoplication was performed with a standard five-port technique with a low pressure of a pneumoperitoneum. The VPS system had no effect on port layout and intraabdominal manipulation and no adverse complications were observed in either case. The effect of a pneumoperitoneum in the VPS system remains controversial, however, the author emphasized that advanced laparoscopic surgery can be performed safely with creating a low pressure of a pneumoperitoneum.

Preparation, structure, and amphoteric redox properties of p-phenylenediamine-type dyes fused with a chalcogenadiazole unit

4,7-Bis(dialkylamino)benzo[c][1,2,5]chalcogenadiazoles are a novel class of organic dyes that undergo reversible two-stage one-electron oxidation as well as one-electron reduction. They exhibit absorption maxima in the long-wavelength region, which are assigned as intramolecular charge transfer bands from the phenylenediamine moiety to the electron-accepting heterocycle. Their redox properties as well as molecular and crystal structures are affected by the alkyl substituents on the amino nitrogen and/or by the chalcogen atom (O, S, Se) in the heterocycle.

Plasma endothelin-1 level as a marker reflecting the severity of portal hypertension in biliary atresia

BACKGROUND/PURPOSE

The aim of this study was to examine if the plasma endothelin-1 (ET-1), a potent vasoconstrictor, level may reflect the severity of portal hypertension associated with liver cirrhosis in biliary atresia (BA).

METHODS

Forty-eight postoperative BA patients aged 6 months to 20 years were studied. Plasma ET-1 was measured by a sandwich method of enzyme immunoassay. ET-1 was compared with Child's score and laboratory data. ET-1 levels were compared among groups of patients with various degrees of histologic fibrosis and portal hypertension.

RESULTS

Plasma ET-1 was 5.3 +/- 3.5 pg/mL in BA, higher than in controls (3.1 +/- 0.8, n = 27; P <.05). ET-1 correlated with Child's score, serum total bilirubin, direct bilirubin, aspartate aminotransferase, albumin, prothrombin time, hepaplastin test, fibrinogen, cholinesterase, total cholesterol, Fischer's molar ratio, prealubumin, and hyaluronic acid, respectively (P <.05). ET-1 also correlated with the severity of histologic fibrosis, gastroesophageal varices, the presence of splenomegaly, ascites, venous dilatation on the abdominal wall, or pulmonary vascular abnormalities. In 4 patients undergoing liver transplantation (LTx), ET-1 after LTx was lower than that before LTx (P <.05).

CONCLUSION

Plasma ET-1 level may be a useful index reflecting the severity of cirrhosis and portal hypertension in BA.

Membrane-type 5 matrix metalloproteinase is expressed in differentiated neurons and regulates axonal growth

Expression of membrane-type (MT) 5 matrix metalloproteinase (MMP) in the mouse brain was examined. MT5-MMP was expressed in the cerebrum in embryos, but it declined after birth. In contrast, expression in the cerebellum started to increase postnatally and continued thereafter. The cells expressing MT5-MMP were postmitotic neurons that showed gelatinolytic activities. Specific expression of MT5-MMP was observed in the neurons but not in the glial cells when embryonal mouse carcinoma P19 cells were differentiated in vitro by retinoic acid treatment. Neurons isolated from dorsal root ganglia also expressed MT5-MMP, and it was localized at the edge of growth cone. Proteoglycans inhibit neurite extension and regulate synaptogenesis. The inhibitory effect of the proteoglycans on neurite extension of dorsal root ganglia neurons was effectively eliminated by recombinant MT5-MMP. Thus, MT5-MMP expressed in neurons may play a role in axonal growth that contributes to the regulation of neural network formation.

Pectus excavatum repair using a costal cartilage graft for patients with tracheobronchomalacia

BACKGROUND

Pectus excavatum is sometimes associated with tracheobronchomalacia, which usually manifests left mediastinal shift, atelectasis of the left lung, and recurrent pulmonary infection. Standard repair of pectus excavatum alone usually failed to improve symptoms.

METHODS

Pexis of the great vessels and pericardium combined with the support of the lower sternum, using a contralateral costal cartilage graft following the standard Ravitch's repair of pectus excavatum, has been used in 6 children during the past 5 years. In addition to respiratory symptoms, diagnosis of tracheobronchomalacia was made by bronchoscopy using an ultrathin fiberscope.

RESULTS

Using the described operative technique, an excellent cosmetic and functional result was obtained in 5 of 6 children. However, atelectasis of the left lower lobe and the narrowing of the left mainstem bronchus continued postoperatively in one patient, which required the insertion of the Palmaz stent in the left mainstem bronchus.

CONCLUSION

This technique may help improve tracheobronchomalacia in patients with pectus excavatum and should be tried before the insertion of an internal stent.

Motor abnormality in the gastroduodenal junction in patients with infantile hypertrophic pyloric stenosis

BACKGROUND/PURPOSE

Periodic clusters of phasic pressure waves in the gastroduodenal junction (GDJ) have been seen in patients with infantile hypertrophic pyloric stenosis (IHPS). This study investigated the details of these pressure waves in relation to disturbed transpyloric flow in IHPS.

METHODS

Manometric study was performed in 11 IHPS patients before and after atropine therapy and 2 non-IHPS infants. Pressure changes in the GDJ were measured with an 8-channel sleeve or a 9-channel sidehole micromanometric assembly under fluoroscopic control for 2 hours.

RESULTS

Clusters of phasic pressure waves (365 +/- 42 mm Hg) associated with an increase in basal pressure (10 +/- 3 mm Hg) were intermittently observed in the GDJ in all IHPS patients. Similar observations were not made in the non-IHPS infants. Most antral pressure waves occurred simultaneously with those pressure waves in the GDJ in the IHPS patients. Atropine (0.01 mg/kg) transiently abolished the phasic and tonic pressure waves for 19 +/- 10 minutes. Significantly fewer phasic pressure waves were observed after atropine therapy.

CONCLUSIONS

Characteristic phasic and tonic contractile activity in the GDJ is uncoordinated with the antral contractions in IHPS patients. Such incoordination may be an important factor in the disturbed transpyloric flow in IHPS.

Dynamic change of cells expressing MMP-2 mRNA and MT1-MMP mRNA in the recovery from liver fibrosis in the rat

BACKGROUND/AIMS

The aim of this study was to investigate whether both matrix metalloproteinase-2 (MMP-2) and membrane type 1 MMP (MT1-MMP) participate in the spontaneous resolution of liver fibrosis.

METHODS

Transcription of both genes was examined by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). Gelatinase activity was investigated by zymography.

RESULTS

Gene expression by RT-PCR showed that both genes increased in the process of liver fibrosis, then decreased gradually in the recovery phase. ISH revealed that distribution of positive cells changed quickly in the recovery phase. Positive cells were widely seen in the liver, mainly around fibrous septa, in the aggressive phase, but were exclusively observed at the interface between the resolving fibrous band and the parenchyma, then were diffusely located in the lobules in the recovery phase. Main cells expressing both mRNAs seemed to be stellate cells for their morphology, though they did not express characteristic cell markers. Some hepatocytes and Kupffer cells expressed both mRNAs in the recovery phase. Gelatinase activity of MMP-2 increased in the recovery phase of 8-week-treated rat liver by gelatin zymography.

CONCLUSIONS

The results of present study suggest that both enzymes participate in the destruction of extracellular matrix in coordination with MMP-13.

Cryopreservation-induced acrosomal vesiculation in live spermatozoa from cynomolgus monkeys (Macaca fascicularis)

BACKGROUND

Cryopreserved spermatozoa are known to undergo accelerated capacitation and require a shorter incubation time for fertilization. However, details of their acrosomal membranes following cryopreservation remain unclear.

METHODS

Percoll density gradient centrifugation was used to remove dead spermatozoa; thus >90% live spermatozoa were recovered after cryopreservation, and acrosomal status was compared among non-incubated and incubated fresh and cryopreserved spermatozoa.

RESULTS

Transmission election microscopy (TEM) using microwave methods and fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (FITC-PSA) staining revealed that 21.1 and 61.6% respectively of non-incubated, cryopreserved spermatozoa were intact, whereas 97.6% (TEM) or 91.9% (FITC-PSA) of non-incubated fresh spermatozoa were intact. TEM revealed that 28.8% of the cryopreserved spermatozoa were swollen, and probably included among those counted as intact by FITC-PSA staining. The non-incubated cryopreserved spermatozoa had fused plasma and outer acrosomal membranes, and 36.4% of them had vesiculation when observed by TEM. FITC-PSA staining indicated that 22% of the live spermatozoa were acrosome reacted.

CONCLUSIONS

Acceleration of the acrosome reaction was evident by both TEM and FITC-PSA. Incubation of cryopreserved spermatozoa for 2 h accelerated vesiculation to a state similar to that of fresh spermatozoa that had been incubated for 8 h. These results reveal that in cryopreserved spermatozoa, the process of acrosome reaction begins before incubation.

[A case of postoperative multiple hepatic metastasis from esophageal cancer successfully treated by surgical resection and hepatic arterial infusion chemotherapy]

A 66-year-old male who underwent radical resection for esophageal cancer (stage IV) was diagnosed with multiple hepatic metastasis 1 year and 3 months after the surgery. He underwent hepatic resection and received systemic chemotherapy (FAP: 5-FU, ADR, CDDP), as the post-operative adjuvant therapy. One year and 3 months later, there was a huge recurrence in the residual liver and hepatic arterial infusion chemotherapy (FAP) was performed. The recurrent lesion disappeared completely after 3 sessions of arterial infusion chemotherapy. The arterial infusion chemotherapy was continued in the outpatient clinic and the recurrent lesion is well controlled. At present, this patient has returned to social life, 2 years and 3 months after the hepatic resection. The utility of hepatic arterial infusion chemotherapy and hepatectomy for postoperative multiple hepatic metastasis from esophageal cancer was shown in the present case.

Effect of diethylstilbestrol on cell proliferation and expression of epidermal growth factor in the developing female rat reproductive tract

To evaluate mechanisms of cell proliferation in the fetal female rat reproductive tract, diethylstilbestrol (DES) effects on cell division and estrogen receptor (ER), epidermal growth factor (EGF) and EGF receptor (EGF-R) expressions were determined from gestational day (GD) 15.5 to 21.5. Reproductive tracts were evaluated within three regions along the Müllerian duct axis; these were proximal, middle and caudal, which differentiate into oviduct, uterus and upper vagina respectively. In fetuses from non-treated dams, epithelial and mesenchymal proliferation, as evaluated by 5-bromo-2'-deoxyuridine incorporation, was decreased with development in all regions of the Müllerian duct. EGF levels were determined by immunohistochemistry. Müllerian epithelial EGF immunoreactivity was intense in the proximal and middle regions on GDs 15.5 and 17.5. EGF staining remained intense only in the proximal epithelia by GD 19.5 and was weak in the caudal epithelium, but substantially reduced throughout epithelia in all regions by GD 21.5. Thus, decreased cell proliferation correlated with decreased EGF expression in the developing Müllerian duct. DES (100 microg/kg body weight) was injected from GD 15 to 19 and female fetuses were collected on GD 19.5. DES increased Müllerian duct cell proliferation in the proximal epithelium and mesenchyme but decreased it in the caudal epithelium compared with oil-treated controls. No proliferative DES effect was observed in any cell type in the middle region. Müllerian duct EGF immunoreactivity was suppressed by DES compared with oil. Competitive RT-PCR indicated DES also decreased mRNAs for EGF, ERbeta1 and ERbeta2, but not ERalpha and EGF-R. These results indicate EGF may be an important regulatory factor of Müllerian duct cell proliferation, and that DES may alter cell proliferation by disrupting normal EGF, ERbeta1 and ERbeta2 expression in the developing female rat reproductive tract.

High frequency of beta-catenin mutations in hepatoblastoma

Hepatoblastoma (HB) is an embryonic neoplasm representing the most frequent malignant liver tumour in childhood. Its tumourigenesis at the molecular level is still poorly understood, and candidate genes are yet to be identified. According to recent reports describing beta-catenin mutations (BCM) at hot-spot regions involving exon 3 in several types of malignancies including HB, we investigated BCM in 16 HBs classified into different histological types. One tumour had been previously confirmed to harbour adenomatous polyposis coli (APC) mutations that exhibit a similar oncogenic effect to that of BCM. Mutations in both exon 3 and its flanking region of the beta-catenin gene were investigated and determined. Twelve tumours (75%) revealed pathogenic BCM, including 5 with missense mutations at codons 32, 34, or 37 and 7 with interstitial deletions that partially or totally affected exon 3. All 7 deletions were in-frame deletions without frameshift. A single nucleotide change at codon 31 regarded as non-pathogenic polymorphism was detected in the tumour possessing APC mutations. Therefore, a total of 13 tumours (81%) were compromised by an enhanced beta-catenin-mediated transcription pathway. Mutations were observed in every histological type of HB. The very high frequency without correlation to histological type indicates that BCM are crucial events in the tumourigenesis of HB.

Protonation of histidine and histidine-tryptophan interaction in the activation of the M2 ion channel from influenza a virus

The M2 protein of influenza A virus forms a homotetramer ion channel in the lipid membrane. The channel is specific for proton conductance and is activated by low pH with a transition midpoint at pH 5.7. We have studied the structure of the transmembrane domain of the M2 ion channel by using UV resonance Raman spectroscopy, with special attention to the side chains of histidine (His37) and tryptophan (Trp41) residues. The Raman spectra provide direct evidence that the imidazole ring of His37 is protonated upon channel activation at low pH. Concomitantly, the UV resonance Raman scattering from Trp41 shows an unusual intensity change, which is ascribed to a cation-pi interaction between the protonated (cationic) imidazole ring of His37 and the indole ring of Trp41. The protonation of His37 and the Raman intensity change of Trp41 do not occur in the presence of amantadine that blocks the M2 ion channel. These observations clearly show that the protonation of His37 and concomitant cation-pi interaction with Trp41 is a key step in the activation of the M2 ion channel. The His37-Trp41 interaction associated with the channel activation is explained by assuming a conformational transition of His37 induced by electrostatic repulsion among the protonated imidazole rings of four His37 residues in the tetramer channel. Trp41 may play a role in stabilizing the channel open state through cation-pi interaction with His37. A molecular model for the activation of M2 ion channel is proposed on the basis of the gating mechanism.

[Bacterial contamination of salvaged blood in open heart surgery: is that an airborne contamination or a normal skin flora contamination?]

We investigated sources of bacterial contamination of intraoperative salvaged blood producted by autologous transfusions device (CS; CELL SAVER 5, Heamonetics Corp., Braintree, MA). Eleven patients undergone open heart surgeries including 2 emergency operations with a median sternotomy enrolled in this study. Blood samples were drawn from salvaged blood bags. Airborne contaminants (AB) were collected by a blood agar plate put besides the operation bed for 30 minutes. The median wounds samples were collected by a swab. Bacterial growth was detected in 81.8% of salvaged blood samples. Twenty-nine bacterium were isolated from CS, 72.4% of those were Staphylococci. 9.1% of sample was positive in wound swabs. Forty bacterium were isolated from plate cultures. 65% of them were Staphylococci. Staphylococcus epidermidis and coagulase negative Staphylococcus isolated both CS and AB in the 2 cases had the same identify codes, and incubated from several AB cultures. Corynebacterium sp. is also isolated from both CS and AB cultures in other 2 same cases. In 7 out of 8 cases (87.5%), from which Staphylococci isolated in CS, the Staphylococci were cultured from AB in not the same but the other cases. In conclusion, highly incidence of the identification in identical code of Staphylococci indicated that the main source of CS contamination was highly suspected to AB.