Inhaling gas with different CT densities allows detection of abnormalities in the lung periphery of patients with smoking-induced COPD

STUDY OBJECTIVES

To establish a novel method allowing detection of regional abnormalities in gas distribution at the acinar level by high-resolution CT (HRCT).

PARTICIPANTS

Nonsmoking control subjects (n = 28) and patients with smoking-induced COPD (n = 47).

MEASUREMENTS AND RESULTS

Changes in lung CT densities were examined by HRCT while the subjects inhaled a gas mixture consisting of 21% O(2) in SF(6) or 21% O(2) in He. HRCT images of the right upper and lower lung fields were obtained at the end of inspiration and expiration of the second and 60th breaths after the start of each gas. Introducing mean lung density (MLD) and relative area with low CT attenuation (%LAA), we analyzed the differences in acinar SF(6) and He distribution in the early phase (second breath) and in the equilibrium state (60th breath). We found that the differences in inspiratory MLD between the SF(6) and He images at the 60th breath were qualitatively consistent with the differences predicted from the physical properties of these gases. However, the differences in inspiratory MLD between the SF(6) and He images taken at the second breath were smaller than those at the 60th breath, especially in the smoking group with COPD. These differences in second-breath inspiratory MLD in the smoking group were smaller in the upper lung field than in the lower lung field. The differences in MLD between the two gases were not detected at end-expiration at the time of either the second or 60th breaths. The %LAA values did not differ between the SF(6) and He images in either the nonsmoking group or the smoking group.

CONCLUSIONS

SF(6)/He-associated HRCT images obtained at end-inspiration, but not at end-expiration, in the early breathing phase are useful for predicting acinar gas distribution abnormalities in patients with COPD.

Enhanced proliferation and differentiation of rat hepatocytes cultured with bone marrow stromal cells

Liver transplantation is the only clinically effective method of treating acute liver failure. However, wider application of this therapeutic modality is restricted primarily by shortage of donor organs. In the search for alternative methods of liver replacement therapy, investigators have focused on transplantation of normal allogeneic hepatocytes and on the development of liver support systems utilizing isolated hepatocytes. Since all human livers suitable for cell harvest are being used for transplantation, hepatocyte therapy using human tissue would require growing of cells in vitro. Unfortunately, although hepatocytes have tremendous capacity to proliferate in vivo, their ability to grow in culture is severely limited. Stromal cells from bone marrow and other blood-forming organs have been found to support hematopoiesis. In this paper, we show that bone marrow-derived stromal cells (BMSCs) enhance proliferation and support differentiation of rat hepatocytes in culture. Further, we demonstrate that in hepatocyte/BMSC co-cultures, clonal expansion of small hepatocytes (SH) is increased. Using semipermeable membrane cultures, we established that direct cell-cell contact is necessary for stimulation of cell proliferation. We also show that BMSCs which are in direct contact with hepatocytes and SH colonies express Jagged1. This suggests a potential role for Notch signaling in the observed effects. Finally, we present evidence that the expression and activity of liver specific transcription factors, CCAAT/enhancer binding proteins and liver specific key enzymes such as tryptophan 2,3-dioxygenase, are improved in hepatocyte/BMSC co-cultures. In conclusion, results of this study indicate that BMSCs could facilitate proliferation and differentiation of primary rat hepatocytes and their progenitors (SH) in vitro.

Familial frontotemporal dementia and parkinsonism with a novel N296H mutation in exon 10 of the tau gene and a widespread tau accumulation in the glial cells

We report a 62-year-old Japanese man with familial frontotemporal dementia and a novel missense mutation (N296H) in exon 10 of the tau gene. The patient presented with frontal signs followed by temporal signs and parkinsonism. The brain showed localized frontotemporal lobe atrophy including the precentral gyrus and discoloration of the substantia nigra, and revealed severe neuronal loss with proliferation of tau-positive protoplasmic astroglia in the affected cerebral cortex, tau-positive coiled bodies and threads in the subcortical white matter, and tau-positive pretangle neurons in the subcortical and brain stem nuclei. There were no tau-positive neurofibrillary tangles, Pick bodies, tuft-shaped astrocytes or astrocytic plaques in the cerebral cortex. Immunoelectron microscopically, phosphorylated tau accumulated in both neurons and glial cells in different modalities, such as glial filaments in protoplasmic astroglia, straight tubules in coiled bodies, and free ribosomes in pretangle neurons. These findings suggest that tau proteins are not always assembled in abnormal filaments such as twisted ribbons, paired helical filaments and straight tubules in neurons and glial cells, which have been shown in previous cases with frontotemporal dementia and parkinsonism linked to chromosome 17. Immunoblotting of sarkosyl-insoluble tau exhibited accumulation of four-repeat tau isoforms in the brain. The N296H mutation may interfere with the ability of mutated tau to bind with microtubules and lead to tau aggregation. Further study is necessary to determine whether this mutation can account for the characteristic tau pathology of this case.

Light regulation of circadian clock-controlled gene expression in rice

Using transgenic rice seedlings expressing a firefly luciferase (luc) gene under the control of a rice CAB (chlorophyll a/b binding protein) promoter, we demonstrated how light affects circadian clocks in the transcription of the CAB gene. Rhythmic luc expression was observed for more than 5 d under constant light and dark (DD) conditions after light/dark entrainment. After a light pulse was applied at different time points in DD various temporal patterns of CAB gene expression were individually observed. We first examined two distinct properties related to the entrainment mechanism of the circadian clock: fluence-rate dependence of free-running periods (FRPs) and phase resetting by a light pulse. Although fluence-rate dependent shortening of FRP was demonstrated, the FRP in DD was almost equal to that in constant light of a middle fluence-rate, indicating that this fluence-rate dependence may not fully describe the entrainment of the circadian clock in rice. Typical phase responses of the circadian clock by a single light pulse were also observed at the transcriptional level in rice seedlings. Thus, the phase resettings upon the light/dark transitions of daily cycles may be sufficient to explain the entrainment mechanisms of rice. We have further demonstrated that, in addition to having a gating effect to acute response, a light pulse can activate the circadian clock-controlled CAB1R gene expression at the first circadian peak in a phase-dependent manner. This suggests that light activates circadian clock activity in the diurnal CAB gene expression under daily light/dark cycles.

The Association of High Jugular Bulb Venous Oxygen Saturation with Cognitive Decline After Hypothermic Cardiopulmonary Bypass

This study was conducted to investigate whether jugular bulb venous oxygen saturation (SjVO(2)) predicted cognitive decline after cardiac surgery with hypothermic cardiopulmonary bypass (CPB). We studied 35 patients undergoing cardiac surgery. After the induction of anesthesia, a 5.5F fiberoptic oximetry catheter was retrogradely inserted into the jugular bulb, and SjVO(2) and other cerebral oxygenation variables were analyzed before, during, and after CPB. At each point, an oxyhemoglobin dissociation curve was drawn, and the P(50) value of jugular bulb venous blood was calculated by computer analysis. Cognitive function was assessed with the revised version of Hasegawa's Dementia Scale and the Benton Revised Visual Retention Test before and early after the operation. In 15 patients (the Decline group), cognitive function was declined after surgery, whereas it remained unchanged in 20 patients (the Normal group). SjVO(2) was significantly higher and cerebral oxygen extraction was significantly lower before and during CPB in the Decline group than in the Normal group (P < 0.05). The oxygen pressure at an oxygen saturation of 50% was significantly lower before and after CPB in the Decline group than in the Normal group (P < 0.05). Logistic regression analysis showed that high SjVO(2) was a predictor of cognitive decline after cardiac surgery. We conclude that high SjVO(2) was associated with cognitive decline after cardiac surgery with hypothermic CPB.

IMPLICATIONS

Jugular bulb venous oxygen desaturation has been suggested as a predictor of cognitive decline after cardiac surgery. However, the clinical value of jugular bulb venous oxygen saturation (SjVO(2)) may be limited during hypothermic cardiopulmonary bypass (CPB) when oxygen affinity to hemoglobin is increased. This study shows that high SjVO(2) before and during hypothermic CPB is a predictor of subsequent cognitive decline.

A pediatric patient with classical citrullinemia who underwent living-related partial liver transplantation

Patients with inborn errors of metabolism undergo liver transplantation, but the effect of transplanting the liver of healthy carriers of these conditions has not been fully clarified. A 6-year-old girl with classical citrullinemia, who repeatedly suffered from hyperammonemia, underwent living-related liver transplantation by using a segment of the liver of her mother, who was a heterozygote carrier for classical citrullinemia. Hyperammonemia alleviated in the patient after the transplantation, thereby dramatically improving her quality of life. Although the levels of plasma and urinary citrulline remained high postoperatively, there was no marked difference in the level of plasma citrulline up to 1 month after surgery when compared with that of previously reported orthotopic liver transplantation cases with classical citrullinemia.

Synthesis of TiRru2 heterobimetallic and TiRuM (M = Rh, Rr, Pd, Pt) heterotrimetallic sulfido clusters from a hydrosulfido-bridged titanium-ruthenium complex

Treatment of the hydrosulfido-bridged titanium-ruthenium heterobimetallic complex [Cp2Ti(mu2-SH)2RuCl(eta5-C5Me5)] (1; Cp = eta5-C5H5) with an excess of triethylamine followed by addition of [RuCl2(PPh3)3] and [[(cod)M]2(mu2-Cl)2] (M = Rh, Ir; cod = 1,5-cyclooctadiene) led to the formation of the TiRu2 and TiRuM mixed-metal sulfido clusters [(CpTi)[(eta5-C5Me5)Ru][Ru(PPh3)2](mu3-S)2(mu2-Cl)2] (3) and [(CpTi)[(eta5-C5Me5)Ru][M(cod)](mu3-S)2(mu2-Cl)] (M = Rh (4a), Ir (4b)), respectively. On the other hand, the reactions of 1 with [M(PPh3)4] (M = Pd, Pt) afforded the TiRuM trinuclear clusters [(CpTiCl)[(eta5-C5Me5)Ru][M(PPh3)2](mu3-S)(mu2-S)(mu2-H)] (M = Pd (5a), Pt (5b)) with an unprecedented M3(mu3-S)(mu2-S) core. The detailed structures of these triangular clusters 3-5 have been determined by X-ray crystallography. Crystal data: 3, triclinic, P1, a = 12.448(4) A, b = 12.773(4) A, c = 17.270(4) A, alpha = 100.16(2) degrees, beta = 99.93(2) degrees, gamma = 114.11(3) degrees, V = 2373(1) A(3), Z = 2; 4a, triclinic, P1, a = 7.714(2) A, b = 11.598(3) A, c = 14.802(4) A, alpha = 80.46(2) degrees, beta = 82.53(2) degrees, gamma = 71.47(2) degrees, V = 1234.0(6) A3, Z = 2; 4b, triclinic, P1, a = 7.729(1) A, b = 11.577(2) A, c = 14.766(3) A, alpha = 80.14(1) degrees, beta = 82.71(1) degrees, gamma = 71.55(1) degrees, V = 1231.1(4) A3, Z = 2; 5a, monoclinic, P2(1)/c, a = 11.259(4) A, b = 16.438(4) A, c = 26.092(5) A, beta = 102.23(3) degrees, V = 4719(2) A(3), Z = 4; 5b, monoclinic, P2(1)/n, a = 11.369(2) A, b = 16.207(3) A, c = 26.116(2) A, beta = 102.29(1) degrees, V = 4701(1) A3, Z = 4.

No evidence of an association between CYP2D6 polymorphisms among Japanese and dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is the second most frequent degenerative dementia among the elderly, following Alzheimer-type dementia (ATD). An association of DLB with CYP2D6*4, one of the cytochrome P450IID6 (debrisoquine 4-hydroxylase; CYP2D6) gene polymorphisms, was reported previously, but this is controversial. Moreover, these reports have been restricted to Caucasian populations. Therefore, we compared frequencies of CYP2D6*3, *4, and *10 mutant alleles in 17 Japanese DLB patients to those among Alzheimer-type dementia (ATD) patients and healthy controls. Polymerase chain reaction amplification and restriction fragment length polymorphism analyses were used for genotyping. No significant difference of genotype or mutant allele frequencies was detected between DLB, ATD, and healthy controls. The present results do not support the suggestion that the CYP2D6 gene is related to DLB susceptibility, at least in the Japanese population.

Bcl-2 inhibits apoptosis of spermatogonia and growth of spermatogonial stem cells in a cell-intrinsic manner

The growth, differentiation, and death/survival of spermatogonia are precisely regulated for the proper production of spermatozoa. We have previously shown that Bcl-2 ectopically expressed in spermatogonia caused the inhibition of normal spermatogonial apoptosis and the subsequent failure of differentiation in transgenic mice. In addition, the growth of spermatogonial stem cells seemed to be temporally arrested in the transgenic mice. In the present study, we attempted to examine whether the abnormality of spermatogonia described above was caused by Bcl-2 misexpression in the spermatogonia or by an abnormal spermatogenic environment of the transgenic mice. We transplanted testicular cells of transgenic mice to seminiferous tubules of W/Wv mice in which transplanted normal testicular cells can undergo spermatogenesis. We found that the transplanted spermatogonia of the transgenic mice reproduced a series of abnormal changes including temporal growth arrest of spermatogonial stem cells and abnormal accumulation of spermatogonia in tubules, which were also observed in the testes of the transgenic mice. The results indicated that Bcl-2 inhibited apoptosis of spermatogonia and growth of spermatogonial stem cells in a cell-intrinsic manner. We also cultured testicular cells of transgenic mice and found that the spermatogonia of the transgenic mice were better able to survive than were those of wild-type mice but that their differentiation was not affected. The result suggested that failure of differentiation of the accumulated spermatogonia in the transgenic testes is not due to the abnormality of the bcl-2 misexpressing spermatogonia, but may be caused by extrinsic problems including improper interaction of spermatogonia with supporting cells.

Safe and efficient gene transfer into porcine hepatocytes using Sendai virus-cationic liposomes for bioartificial liver support

Establishment of a bioartificial liver support system using genetically modified hepatocytes is a potential approach to improve the treatment of severe liver failure. We describe the development of an efficient ex vivo method of gene transfer into a large number of porcine hepatocytes using hemagglutinating virus of Japan (HVJ)-liposome. The transfection efficiency of HVJ-liposome into isolated porcine hepatocytes attached to microcarrier beads was evaluated by beta-galactosidase (beta-gal) staining, fluorescence activated cell sorting analysis for beta-gal and luciferase assay, respectively. To examine the function and cellular damage of transduced hepatocytes, we used enzyme-linked immunosorbent assay for porcine albumin synthesis, lidocaine clearance test (P-450 activity), aspartate aminotransferase, and lactic dehydrogenase release assays. The optimal conditions for gene transfer into the beads-attached hepatocytes using HVJ-liposome included 4 microg of deoxyribonucleic acid with 200 microg of lipid/2 x 105 cells and exposure duration of 90 min. Under these conditions, beta-gal and luciferase genes were transduced to 2.5 x 108 isolated porcine hepatocytes following attachment to the beads. Positive beta-gal staining was observed in more than 30% of the beads-attached hepatocytes. The gene transfer activity of HVJ-liposome method determined by luciferase activities was about 100-fold of that of the lipofection method. Transfected porcine hepatocytes remained functional without any significant cell damage. Our results demonstrated that HVJ-liposome mediated gene transfer into microcarrier-attached porcine hepatocytes is an efficient and nontoxic method suitable for a bioartificial liver support sytem.

Recurrence of Cushing's disease after long-term remission due to pituitary apoplexy

We encountered a case with long-term remission of Cushing's disease due to pituitary apoplexy. The apoplexy of pituitary adenoma secreting adrenocorticotropin hormone was diagnosed by successive and timely magnetic resonance imaging when the symptoms of the patient were not yet severe and anterior pituitary dysfunction was only a transient reduction of growth hormone secretion. Seven years after the first episode of pituitary apoplexy, hypercorticism recurred, and pituitary magnetic resonance imaging showed a regrowth of the pituitary adenoma. A spontaneous remission of Cushing's disease without significant visual, neurologic or hormonal defects seems to be a much more common phenomenon than has been previously suggested. Cases with relapse after spontaneous remission of Cushing's disease are rare and the duration of remission in previous reports was within 5 years. We observed such a patient with a 7 year-remission caused by pituitary apoplexy. We consider that a careful long-term follow-up is required for patients with Cushing's disease whose remission was due to pituitary apoplexy.

Establishment and characterization of a colonic epithelial cell line MCE301 from transgenic mice harboring temperature-sensitive simian virus 40 large T-antigen gene

We produced an immortalized colonic epithelial cell line, MCE301, using fetal mice transgenic for the temperature-sensitive simian virus 40 large T-antigen gene. MCE301 cells showed epithelial-like morphology and maintained tight connections with neighboring cells. The cells grew at a permissive temperature (33 degrees C), but the growth of the cells was significantly prevented at the nonpermissive temperature (39 degrees C). The cells expressed large T-antigen at 33 degrees C but not at 39 degrees C. MCE301 cells were not transformed, as judged by the absence of anchorage-independent growth in soft agar gel and lack of tumor formation in nude mice. Electron microscopic studies showed that the cells formed microvilli-like structures on the cell surface and junctional complexes such as tight junctions and desmosomes between the cells. The cells expressed cytosketal (acidic cytokeratins and actin), basement membrane (laminin and collagen type IV) and junctional complex proteins (ZO-1 and desmoplakin I + II), as judged by specific antibodies. Fetal bovine serum, epidermal growth factor, insulin-like growth factor and insulin significantly increased the cell growth at 33 degrees C. Moreover, MCE301 cells expressed colonic mucin Muc2 mRNA as demonstrated by reverse transcriptase-polymerase chain reaction, indicating that the cells originate from mucus-secreting cells. Alkaline phosphatase, a brush border-associated enzyme, was detected in the cells. Sodium butyrate (2 mM), an inducer of cellular differentiation, markedly elevated alkaline phosphatase activity. Thus, the present mouse colonic epithelial cell line MCE301 possessing these unique characteristics should provide a useful in vitro model of colonic epithelium.

Lack of association in Japanese patients between neuroleptic malignant syndrome and a debrisoquine 4-hydroxylase genotype with low enzyme activity

Decreased activity of debrisoquine 4-hydroxylase (CYP2D6), which participates in hepatic metabolism of several frequently used neuroleptics and antidepressants, is inherited as an autosomal recessive trait through polymorphic CYP2D6 gene alleles. In eastern Orientals, a C --> T substitution at nucleotide 188 (Pro34Ser) is primarily responsible for decreased ability to metabolize CYP2D6 substrates. We therefore studied a possible association between neuroleptic malignant syndrome (NMS) and the C188T mutation. We examined the frequency of the C188T mutation by polymerase chain reaction and restriction fragment length polymorphism analysis in 36 Japanese patients previously diagnosed with NMS and 107 neuroleptic-treated schizophrenic patients with no NMS history. The C188T allele frequency was 0.417 in NMS patients and 0.463 in patients without NMS. No significant allele or genotype associations were observed. We cannot conclude that low CYP2D6 activity genotype causes susceptibility to NMS in Japanese patients.

Intraportal administration of low-dose recombinant human hepatocyte growth factor enhances effects of hepatocellular transplantation

BACKGROUND/AIMS

Although recombinant human hepatocyte growth factor (rhHGF) is a potent mitogen, the dose used for patients is still not clear and must be low to avoid untoward effects. Firstly, the optimal strategy of the dose and route of rhHGF was investigated. Secondly, low-dose rhHGF, which would induce proliferation of transplanted hepatocytes, was explored using Nagase analbuminemic rats.

METHODOLOGY

1) Concentrations of rhHGF in the portal vein were measured after continuous administration of titrated rhHGF through the jugular vein or portal vein. 2) F344 rat hepatocytes (2 x 10(7) cells) were transplanted in the liver of Nagase analbuminemic rats. On the 7th day, the rats were subjected to a low-dose rhHGF treatment.

RESULTS

When the rats were given rhHGF in a dose of 50 micrograms/kg/day, the mean concentration in the portal vein (0.8 +/- 0.1 ng/mL) was almost similar to the minimum concentration which stimulated hepatocyte proliferation in vitro. When low-dose rhHGF (50 micrograms/kg/day) was administered directly into the portal vein following hepatocyte transplantation in Nagase analbuminemic rats, the serum levels of albumin were significantly higher than in other groups. It was found that the concentration of rhHGF in the portal vein were 3.1 +/- 0.5 ng/mL with continuous intraportal infusion and 0.8 +/- 0.1 ng/mL with continuous systemic infusion.

CONCLUSIONS

It was found that the minimal dose of rhHGF needed to stimulate hepatocyte proliferation was 50 micrograms/kg/day. With rhHGF (50 micrograms/kg/day), continuous intraportal infusion afforded a more favorable outcome in case of proliferation of hepatocytes.

Inhibition of signal transducer and activator transcription factor 3 in rats with acute hepatic failure

In fulminant hepatic failure, survival is not possible without recovery of sufficient hepatocyte mass. Remarkably, only a few studies exist that provide insight into the mechanisms that control proliferation of residual hepatocytes after extensive hepatocyte loss. In this regard, the role of growth-regulatory factors, including pro-inflammatory cytokines such as interleukin-6 (IL-6), is not well understood. In the present study we show that in rats with critically low (10%) hepatocyte mass, whether with or without ongoing liver cell necrosis, inhibition of liver regeneration is associated with early and sustained increase in blood IL-6 levels. Under these conditions, the signal transducer and activator of transcription (Stat3) DNA binding activity was lowered at the time of G1/S cell-cycle transition. We further demonstrate that the protein inhibitor of activated Stat3 (PIAS3) and the suppressor of cytokine signaling (SOCS-1) were up-regulated early after induction of liver failure (6-12 h). In vitro, IL-6 induced PIAS3 expression in HGF stimulated rat hepatocytes. These findings suggest that after massive hepatocyte loss, an early and rapid rise in blood IL-6 levels may weaken the hepatic regenerative response through up-regulation of Stat3 inhibitors PIAS3 and SOCS-1.

A novel missense mutation (G209R) in exon 8 of the presenilin 1 gene in a Japanese family with presenile familial Alzheimer's disease. Mutation in brief no. 254. Online

Over fifty missense mutations in the presenilin-1 (PSEN1) gene have been reported in families with presenile familial Alzheimer's disease (FAD). We describe a novel missense mutation (G209R) within the predicted fourth transmembrane domain of the PSEN1 in a Japanese family with presenile FAD. The affected cases showed similar disease histories with the mean age at onset of 49.6 +/- 3.1 years and rapid progressive dementia characterized by memory impairment, amnestic aphasia, disorientation and personality change, but lacking parietal focal symptoms such as apraxia or agnosia. Compared with the previously reported cases of same Gly209 mutation (G209V), the clinical features of the G209R-FAD cases appear to be less critical than those of G209V-FAD cases, although the Gly to Arg mutation is considered to be less conservative than the Gly to Val mutation. These findings may suggest the possible existence of other genetic and/or environmental factors or the possibility that these two different Gly209 mutations may underlie different pathomechanisms in the development of presenile FAD.

Novel acceptor splice site mutation in the invariant AG of intron 6 of alpha-galactosidase A gene, causing Fabry disease. Mutations in brief no. 146. Online

We found a novel acceptor splice site mutation in the invariant AG of intron 6 of alpha-galactosidase A (alpha-Gal A) gene (IVS6-1G->A) in a patient with Fabry disease by sequencing of genomic DNA. Sequencing of RT-PCR revealed the deletion of first base pair (c909del) of exon 7 in mRNA and a frameshift resulting in premature termination. This mutation gives rise to a rare aberrant splicing (Simultaneous 3' destruction and 3' creation).

Unique electroencephalographic change of acute encephalopathy in glutaric aciduria type 1

We report the peculiar serial electroencephalographic (EEG) findings in a 7-year-old boy with glutaric aciduria type 1 during an episode of acute encephalopathy. The patient developed Reye-like syndrome triggered by cellulitis. Cranial magnetic resonance imaging demonstrated diffuse softening of cerebral hemisphere. The EEG on the day following onset of acute encephalopathy showed suppression burst pattern including continuous 14-15 Hz rhythmic waves at first. Then, periodic synchronous discharge appeared and lasted for about 40 minutes. Periodic synchronous discharge finally disappeared and nearly total electrocerebral silence continued. There have been no reports indicating such a change of EEG in a short period. The serial EEG changes probably reflect the process of electrical death of neurons in cerebral hemispheres.

[The effect of preoperative factors on intraoperative oxyhemoglobin dissociation curve]

The position of oxyhemoglobin dissociation curve (ODC) expressed with P50, has a large influence on the oxygen supply. It has been reported that during hypoxia with increased oxygen demand, P50 can increase with a reduction in oxygen affinity. In this study, we investigated the effect of preoperative factors on intraoperative P50 and the relation between the P50 values of the mixed venous blood and those of internal jugular bulb venous blood in seventy patients for cardiac surgery. Preoperative reduction in percentage vital capacity (%VC) and reduced hemoglobin concentration were associated significantly with an increase in intraoperative P50 value. The P50 act (P50 value with only temperature adjusted to 37 degrees C) of the internal jugular bulb venous blood was significantly higher than that of mixed venous blood. These results suggest that intraoperative tolerance to hypoxia and the increase in oxygen demand might be reduced in patients with preoperative abnormality of %VC and the hemoglobin concentration. And this tolerance might be limited in brain.

Limits on neutrino mass from cosmic structure formation

We consider the effect of three species of neutrinos with nearly degenerate mass on the cosmic structure formation in a low-matter-density universe within a hierarchical clustering scenario with a flat Gaussian initial perturbation spectrum. The matching condition for fluctuation powers at the COBE scale and at the cluster scale leads to a strong upper limit on neutrino mass. For a flat universe with matter density parameter Omega = 0.3, we obtain m(nu)<0.6 eV for the Hubble constant H0<80 km s(-1) Mpc(-1). Allowing for the more generous parameter space limited by Omega<0.4, H0<80 km s(-1) Mpc(-1) and age t(0)>11.5 Gyr, the limit is 0.9 eV.

[A successful case of hybrid therapy for the left main trunk and triple coronary vessel lesions with acute myocardial infarction and cardiogenic shock]

A 86-year-patient who had acute myocardial infarction and critical cardiogenic shock was diagnosed to have the left main trunk (LMT) and triple vessel disease. Emergent coronary artery bypass grafting to the left anterior descending artery was performed using saphenous vein graft without cardiopulmonary bypass through median sternotomy. On the 41st postoperative day, catheter intervention was performed to the remaining lesions by stenting of LMT and percutaneous transluminal coronary angioplasty to the right coronary artery lesions. Tl scintigraphy showed remarkable reduction of myocardial ischemia. Hybrid therapy is the effective new strategy for critical cases which cannot be successfully and securely treated by medical or surgical approach alone.

Effects of recombinant human hepatocyte growth factor on the proliferation and function of porcine hepatocytes

A porcine hepatocyte based bioartificial liver (BAL) is still insufficient to replace liver transplantation. In this experiment, to strengthen the performance of a BAL, the effect of human recombinant hepatocyte growth factor (rhHGF) on the proliferation and function of xenogeneic porcine hepatocytes was studied. Isolated porcine hepatocytes were seeded at various densities (5 x 10(3) to 8 x 10(4) cells/well) on a collagen coated 96 well plate in Dulbecco's modified Eagle's medium (DMEM) with 10% FCS. After 4 hours, the medium was changed to DMEM with added insulin and dexamethasone. Subsequently, rhHGF was added at various concentrations (0, 0.625, 1.25, 2.5, 5, 10, 20, 40 ng/ml) and cultured for an additional 24, 48, and 72 hours, respectively. The proliferation of porcine hepatocytes in response to rhHGF reached a plateau at 2.5 ng/ml at 24 hours and subsequently decreased. The levels of porcine albumin vs protein present in the supernatant increased when cultured at high cell density. In conclusion, rhHGF was found to stimulate proliferation of porcine hepatocytes at low cell density and low concentration. rhHGF can also increase albumin synthesis at higher cell density, thus indicating its potential use in a more satisfactory porcine hepatocyte based BAL.

Germline-specific expression of the Oct-4/green fluorescent protein (GFP) transgene in mice

The Pic-1, Oct-1,2, Unc-86 (POU) transcription factor Oct-4 is specifically expressed in the germ cell line, and a previous study has indicated that the expression of the lacZ gene inserted into an 18 kb genomic fragment encompassing the Oct-4 gene can come close to mimicking the endogenous embryonic expression pattern of Oct-4 in transgenic mice. In the present study transgenic mice expressing green fluorescent protein (GFP) in the germ cell line were generated using the same Oct-4 genomic fragments and the expression pattern was analyzed in detail through all stages of germ cell development. The GFP expressing primordial germ cells were first detected as early as 8.0 days post-coitum (d.p.c.; early head fold stage) at the base of the allantois in living embryos. The GFP expression was thereafter found in both male and female germ cells at all developmental stages except in male germ cells after differentiating into type A spermatogonia in the postnatal testis. There was also a lower level of expression in female germ cells in the prophase of the first meiotic division. These transgenic mice therefore proved to be powerful tools for isolating living germ cells at various developmental stages to study their nature and to isolate new genes.

Tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency

Serum phenylalanine concentrations decreased in 4 patients with hyperphenylalaninemia after loading with tetrahydrobiopterin. There were no abnormalities in urinary pteridine excretion or in dihydropteridine reductase activity. However, mutations were detected in the phenylalanine hydroxylase gene, suggesting a novel subtype of phenylalanine hydroxylase deficiency that may respond to treatment with cofactor supplementation.

Cystic lymphangiomas of the colon

We report a patient with cystic lymphangiomas diagnosed by endoscopic ultrasonography and resected by partial polypectomy. A 42-year-old woman consulted a nearby physician because of a positive fecal occult blood test. Barium enema and colonoscopy revealed the presence of abnormalities. On March 11, 1997, she was admitted to our department for further evaluation and treatment. A barium enema examination revealed two protruding lesions in the transverse colon. Colonoscopy showed a teardrop-type mass in the left side of the transverse colon. The mass was cushion-sign positive, and its shape readily changed on respiration and with changes in body position. Another superficial smooth mass was found in the right side of the transverse colon. Ultrasonography of the colon confirmed the presence of a submucosal mass showing a cyst-like pattern. Cystic lymphangiomas were diagnosed and resected endoscopically. Histopathological examination revealed markedly dilated ducts consisting of a single layer of endothelial cells in the submucosa of the colon. The diagnosis was cystic lymphangioma.

Protective effect of nafamostat mesilate on injury of porcine hepatocytes by human plasma

Nafamostat mesilate (NM), a protease inhibitor, possesses a cytoprotective effect and inhibits the activation of complement. The present study investigated whether NM has any protective effect against injury of porcine hepatocytes by human plasma in a bioartificial liver support system. Porcine hepatocytes were harvested and seeded at a density of 2 x 10(5) cells on a 35-mm collagen-coated plate in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal calf serum. Twenty-four hours later, the medium was replaced with human plasma with three concentrations of NM between 3.8 x 10(-5) and 3.8 x 10(-4) M and then cultured for 6 h. The viability of porcine hepatocytes, lactate dehydrogenase (LDH) levels, lidocaine clearance, porcine albumin production, and changes in complement (C3) levels were measured. The viability of porcine hepatocytes in human plasma decreased significantly to 37.7 +/- 11.4% of that in DMEM. NM improved the viability of the hepatocytes, lowered the levels of LDH, and increased lidocaine clearance and albumin production in a concentration-dependent manner. The concentrations of C3, the marker of xenogeneic reactions, did not change significantly, indicating that no hyperacute xenogeneic reaction occurred in our series. Together, our results suggested that NM exerts favorable effects on porcine hepatocytes in human plasma through direct effect such as prevention of protease activity in the plasma membrane of porcine hepatocytes rather than inhibition of complement-dependent immunoreactions.

Efficacy of Nafamostat Mesilate for improving the performance of a bioartificial liver using porcine hepatocytes

Our bioartificial liver (BAL) consists of porcine hepatocytes attached to beads and plasma perfused through the system. The function of our BAL lasts for approximately 7 hours. The objective of the present study was to investigate the efficacy of Nafamostat Mesilate (NM), a protease inhibitor and potent complement inhibitor, for improving the performance of the BAL. The experimental groups were divided as follows; the NM group (n=7) where the BAL had porcine hepatocytes with 3.8x10(-4) M, of NM, and the control group where the BAL had no NM. Plasma obtained from patients suffering from hepatic failure was perfused through the BAL for 10 hours. The viability of the porcine hepatocytes and the levels of alanine aminotransferase (ALT) in the human plasma were measured during perfusion. After the 10-hour perfusion, another human hepatic failure plasma was perfused for an additional 1 hour and then the function of the BAL was evaluated. After the 10-hour perfusion, the viability of the hepatocytes in the NM group was 51 +/- 7%, whereas that in the control group was rapidly reduced by 35 +/- 5%. Although the levels of ALT in the human plasma in both groups increased with the perfusion time, those in the NM group were significantly lower than those in the control group (p < 0.05). These results suggest that NM prevented damage to the porcine hepatocytes in human hepatic failure plasma as compared to the control group. In the human hepatic failure plasma before perfusion, the partial thrombin time (PT) and the plasma ammonia (NH3) levels were 19.8 +/- 12% and 288 +/- 102 microg/dl, respectively. Fischer's ratios were 0.98 +/- 0.39. Even after the 10-hour perfusion, the BAL in the NM group significantly improved the levels of PT (38 +/- 10%; p < 0.05), NH3 (214 +/- 34 microg/dl; p < 0.05) and Fischer's ratios (1.4 +/- 0.3; p < 0.05). On the other hand, the BAL in the control group did not show any improvement in those parameters. In conclusion, NM was found to help in maintaining the viability of porcine hepatocytes in human hepatic failure plasma, thereby allowing the porcine hepatocyte-based BAL to function much better.

[The prognostic value preoperative promontory testing in Japanese cochlear implant patients]

The prognostic value of preoperative promontory testing was evaluated in Japanese cochlear implant patients. Promontory testing consisted of measurement of electrical thresholds (T), uncomfortable level (UCL), dynamic range (DR), gap detection (GAP), and temporal difference limen (TDL). Patients' performances were measured at 3 months (n = 46) and 1 year (n = 20) postoperatively, using a standard Japanese audiologic test battery without lip-reading. This study included only postlingual deaf patients who received the Nucleus multichannel cochlear implant. Wide DRs at low frequencies (50,100,200 Hz) and good GAP detection (< 20 ms) emerged as excellent preoperative predictors of the 3-month postoperative performances (P < 0.05). In contrast, any measurements could not serve as a good predictor of the 1-year performances. These results suggest that the preoperative promontory testing provides useful information only for early postoperative performances but that it could not predict the final language performances.

Effects of anticoagulants on porcine hepatocytes in vitro: implications in the porcine hepatocyte-based bioartificial liver

For the clinical treatment with porcine hepatocyte-based bioartificial liver (BAL), the use of an anticoagulant in the extracorporeal system is essential. In this experiment, we studied the effect of various anticoagulants on cultured porcine hepatocytes. Porcine hepatocytes were isolated and seeded at a density of 2 x 10(5) cells on a collagen-coated plate in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal calf serum (FCS). Twenty-four hours later, the medium was changed to DMEM with various anticoagulants such as nafamostat mesilate (NM), sodium heparin (SH) and sodium citrate (SC) at concentration used clinically. As a control, the hepatocytes were cultured in only DMEM. After culturing for 6 hours, the viability of the porcine hepatocytes, lactate dehydrogenase (LDH) release, lidocaine clearance (cytochrome p450 function) and albumin synthesis were investigated. SC did not affect either the viability or the p450 function of the hepatocytes. In the NM group, the viability of porcine hepatocytes and lidocaine clearance were decreased significantly more than in the other groups. SH did not affect the viability of porcine hepatocytes, however, it seemed to reduce the p450 function. In conclusion, SC may therefore be the optimal anticoagulant available for hepatocyte-based BAL circuit in terms of its cell toxicity.

Management of acute metabolic decompensation in maple syrup urine disease: a multi-center study

BACKGROUND

Therapeutic modalities in acute metabolic decompensation in maple syrup urine disease (MSUD) are variable, and outcomes of each therapeutic measure have been known only individually. Factors that affect neurological outcome are not clear.

METHODS

A questionnaire was sent throughout Japan to each pediatrician treating any of the 42 MSUD patients.

RESULTS

Necessary information was available for 13 patients through the questionnaire, and through a publication for one patient. In nine of the 14 patients episodes of metabolic decompensation developed in the neonatal period. In the other five, the onset of disease was delayed until infancy or later. In the nine patients with neonatal onset, a pretreatment level of plasma leucine greater than 40 mg/100 mL or a duration of altered level of alertness longer than 10 days was associated with a poor neurological outcome. The therapeutic measures employed included intravenous infusion of glucose and electrolyte solution or hypertonic glucose and electrolyte solution, exchange transfusion, peritoneal dialysis, a large dose of thiamine and intravenous hyperalimentation. All patients had survived the episodes and were alive at the time of the survey. Five of the nine patients with neonatal onset have developed neurological sequelae to varying degrees. Episodes of metabolic decompensation in infancy or thereafter did not affect, or only minimally affected, the neurological outcome.

CONCLUSION

Therapeutic goals to improve neurological outcome are to shorten the duration of the altered level of consciousness, and to minimize the peak plasma leucine level as much as possible.

Pelizaeus-Merzbacher disease: three novel mutations and implication for locus heterogeneity

We report a mutational and polymorphic analysis of the proteolipid protein gene in members of 27 Japanese families with Pelizaeus-Merzbacher disease. We found causative mutations in 6 members of 27 families (22.2%); 5 of the 6 mutations, including two novel mutations, Leu45Arg and 231 + 2T --> G, resulted in the typically severe clinical symptoms. Paradoxically, the Cys219Tyr mutation, presumed to disrupt the tertiary structure of proteolipid protein by removing the disulfide bond between Cys200 and Cys219, was associated with a mild clinical presentation wherein the patient could walk with assistance and speak. It was inferred that the structural change prevented the toxicity associated with a gain of function mutation. Moreover, in one family 3 patients exhibited a intragenic polymorphism that did not segregate with the disease, suggesting a locus heterogeneity for Pelizaeus-Merzbacher disease.

Serial electroencephalographic findings in patients with MELAS

To clarify the electroencephalographic characteristics of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS), the medical records and electroencephalograms of six patients with MELAS and two of their relatives with MELA (mitochondrial myopathy, encephalopathy, and lactic acidosis, without strokelike episodes) were retrospectively reviewed. All have a point mutation in the mitochondrial DNA at nucleotide position 3243. The electroencephalograms (n = 79) were divided into four groups according to the time relation to the strokelike episode: (1) before the first strokelike episode, (2) within 5 days after the strokelike episode (acute stage), (3) between 6 days and 1 month after the strokelike episode (subacute stage), and (4) more than 1 month after the strokelike episode (chronic stage). In the acute stage, 10 of the 11 electroencephalograms (9 strokelike episodes in four patients) revealed focal high-voltage delta waves with polyspikes (FHDPS), which were recognized as ictal electroencephalogram. Ictal events during FHDPS included focal clonic or myoclonic seizure and migrainous headache. In the subacute and chronic stages, focal spikes or sharp waves and 14- and 6-Hz positive bursts were frequently recorded. The authors' results suggest that FHDPSs present a reliable and accurate indicator of a strokelike episode in patients with MELAS.

Japanese Creutzfeldt-Jakob disease patients exhibiting high incidence of the E200K PRNP mutation and located in the basin of a river

Seven cases with Creutzfeldt-Jakob disease (CJD) located in the basin of the Fuji river (Fuji area) in Japan were examined genetically and clinicopathologically. The onset of the disease was between 1989 and 1995. All cases were from different families, although 3 cases were family members of previously reported CJD patients. They had clinical and/or neuropathological features, corresponding to subacute spongiform encephalopathy. Five of the 7 cases, including the 3 familial cases, had the E200K mutation in the gene encoding prion protein (PRNP). It is suggested that there is a small cluster of CJD patients with a founder effect of the E200K mutation in the Fuji area, because the incidence of CJD with the E200K mutation appears to be much higher in this area than other areas in Japan. The disease penetrance of the 5 cases with the E200K mutation seems to be low, and they may have an age-related incidence in the Fuji area. These findings support the hypothesis that the phenotypes of CJD patients with the PRNP mutations are linked to the position of the mutation, but not related to ethnic or environmental factors.

Total blood exchange suppresses the early stage of liver regeneration following partial hepatectomy in rats

Despite its obscure and short effect, plasma exchange (PE) remains a mainstay in the treatment of liver disease. However, the question still remains as to whether or not PE suppresses the regeneration of the liver because PE deprives patients of hepatotrophic factors. The effect of PE, which could be a total blood exchange (TBE) in a syngeneic setting, on liver regeneration following a 68% partial hepatectomy (PH) was investigated in rats. In Group 1, 20 ml of blood from normal rats was infused while native blood was removed at 6 and 12 h after PH. In Group 2, 20 ml of blood obtained from PH rats at the same time points was infused. The regeneration rate, labeling index of proliferating cell nuclear antigen (PCNA), and plasma hepatocyte growth factor (HGF) level were determined, and standard liver function tests performed at 24, 48, and 72 h. Although all liver function tests improved in Group 1 at 24 and 48 h, the regeneration rate was significantly impaired. Similarly, the PCNA labeling index was significantly lower in Group 1 than that in Group 2. The plasma HGF level was significantly reduced in Group 1 (6 h blood out versus blood in: 1.1+/-0.5 vs. 0.1+/-0.1 ng/ml, p < 0.05). TBE with normal blood following PH suppressed the early stage of liver regeneration, in part, because of the reduction of HGF even though the blood was purified.

Mutation involving cytochrome P450IID6 in two Japanese patients with neuroleptic malignant syndrome

Cytochrome P450IID6 (CYP2D6) plays an important role in the hepatic metabolism of various psychotropic drugs. We detected a mutation of the CYP2D6 gene in two patients who previously had episodes of neuroleptic malignant syndrome (NMS). They were homozygous for a mutated CYP2D6J allele conferring a poor-metabolizer phenotype. Possession of this trait may contribute to susceptibility to NMS.

Rapid analysis of guanidino compounds in serum from nephritic patients using column-switching with isocratic elution

The rapid method for baseline separation of ten guanidino compounds in serum from nephritic patients was designed using a single eluent with a column switching system. A porous graphitic carbon column and an octadecyl-bonded silica gel columns were used, (50 mm x 4.6 mm i.d.). Separation was completed within 15 min. The stable baseline permitted highly sensitive detection with excellent reproducibility. The system was applied to analyze guanidino compounds in sera from 175 nephritic patients. The hemodialysis process could not completely eliminate guanidino compounds, and the degree of removal varied between patients. The correlation among metabolites indicated the differences in disease.

Lack of association between neuroleptic malignant syndrome and polymorphisms in the 5-HT1A and 5-HT2A receptor genes

OBJECTIVE

The molecular basis of neuroleptic malignant syndrome is unclear, but studies suggest that genetic factors are involved in its pathogenesis. Considering possible involvement of the serotonergic system in neuroleptic malignant syndrome, the authors examined the association between neuroleptic malignant syndrome and polymorphisms of the 5-HT1A and 5-HT2A receptor genes.

METHOD

The authors examined the frequencies of gene polymorphisms in the 5-HT1A (Arg219Leu) and 5-HT2A (Thr25Asn and His452Tyr) receptor genes in 29 patients previously diagnosed with neuroleptic malignant syndrome, 94 neuroleptic-treated patients with schizophrenia who had no history of neuroleptic malignant syndrome, and 94 healthy comparison subjects. Polymerase chain reaction and restriction fragment length polymorphism analyses were used to screen gene mutations.

RESULTS

No polymorphic allele was detected in the patients who had experienced the neuroleptic malignant syndrome.

CONCLUSIONS

The authors cannot conclude that polymorphisms in the 5-HT1A and 5HT2A receptor genes are factors determining susceptibility to the neuroleptic malignant syndrome.

Simple delineation of misery perfusion areas by superimposition of PET on PET images

Oxygen extraction fraction images were superimposed on cerebral blood flow images of positron emission tomography (PET) to depict the so-called misery perfusion area in two patients with moyamoya disease. The superimposed image following extra-intracranial bypass surgery was obtained in one case, which convincingly disclosed attenuation as compared with the preoperative image. This simple PET on PET approach should find an application in the evaluation of misery perfusion and in assessing operative indications for cerebral ischaemic diseases.

Establishment and characterization of tracheal epithelial cell lines, TM01 and TM02-3, from transgenic mice bearing temperature-sensitive simian virus 40 large T-antigen gene

Murine tracheal epithelial cell lines, TM01 and TM02-3, were established from a primary culture of tracheal cells of adult transgenic mice bearing a temperature-sensitive simian virus (SV40) large T-antigen gene. Both TM01 and TM02-3 cells, which grew until confluent monolayers were formed, maintained tight contact with neighboring cells, and retained the characteristics of epithelial cells with microvilli on the surface. These cells grew at a permissive temperature (33 degrees C), but did not at a nonpermissive temperature (39 degrees C), indicating that TM01 and TM02-3 cells undergo temperature-sensitive growth. Large T-antigen was expressed only in the nuclei at 33 degrees C. Sepharose CL-4B column chromatography using a 14C-glucosamine hydrochloride, indicating that both cells produced high molecular weight glycoconjugates, and suggesting that these cells may originate from mucus-producing cells. TM01 cells expressed intercellular adhesion molecular-1 (ICAM-1) in both unstimulated and stimulated (1,000 U/ml tumor necrosis factor-alpha and 500 U/ml interferon-gamma) conditions, whereas TM02-3 cells expressed ICAM-1 only under stimulated conditions. We conclude that these cell lines may serve as a useful model to study the tracheal cell functions under defined in vitro conditions.

Distinctions in agonist and antagonist specificity conferred by anionic residues of the nicotinic acetylcholine receptor

Two anionic residues in the nicotinic acetylcholine receptor, Asp-152 in the alpha-subunit and Asp-174 in the gamma-subunit or the corresponding Asp-180 in the delta-subunit, are presumed to reside near the two agonist binding sites at the alphagamma and alphadelta subunit interfaces of the receptor and have been implicated in electrostatic attraction of cationic ligands. Through site-directed mutagenesis and analysis of state changes in the receptor elicited by agonists, we have distinguished the roles of anionic residues in conferring ligand specificity and ligand-induced state changes. alphaAsp-152 affects agonist and antagonist affinity similarly, whereas gammaAsp-174 and deltaAsp-180 primarily affect agonist affinity. Combining charge neutralization on the alpha subunit with that on the gamma and delta subunits shows an additivity in free energy changes for carbamylcholine and d-tubocurarine, suggesting independent contributions of these residues to stabilizing the bound ligands. Since both aromatic and anionic residues stabilize cationic ligands, we substituted tyrosines (Y) for the aspartyl residues. While the substitution, alphaD152Y, reduced the affinities for agonists and antagonists, the gammaD174Y/deltaD180Y mutations reduced the affinity for agonist binding, but surprisingly enhanced the affinity for d-tubocurarine. To ascertain whether selective changes in agonist binding stem from the capacity of agonists to form the desensitized state of the receptor, carbamylcholine binding was measured in the presence of an allosteric inhibitor, proadifen. Mutant nAChRs carrying alphaD152Q or gammaD174N/deltaD180N show similar reductions in dissociation constants for the desensitized compared with activable receptor state and a similar proadifen concentration dependence. Hence, these mutations influence ligand recognition rather than the capacity of the receptor to desensitize. By contrast, the alphaD200Q mutation diminishes the ratio of dissociation constants for two states and requires higher proadifen concentrations to induce desensitization. Thus, the contributions of alphaAsp-152, gamma/deltaAsp-174/180, and alphaAsp-200 in stabilizing ligand binding can be distinguished by the interactions between agonists and allosteric inhibitors.

Fabrication of High Performance Laminated Polarization Splitters Consisting of Thick a-Si:H /SiO(x):H Multilayers

We report fabrication techniques ofa-Si:H/SiO(x):H multilayers having ample thickness and flat layer boundaries for high performance laminated polarization splitters (LPS's). In the new fabrication process we used the following techniques to achieve low stress and high surface flatness: SiO(x):H film deposition by rf sputtering with a mixture of Ar/H(2), two-step deposition using rf bias sputtering, and elimination of surface roughness and defects by mechanical polishing. This process enabled deposition of a multilayer as thick as 265 mum while preserving layer boundaries as flat as 1 nm (rms). As a result, LPS's having low loss, a large aperture, and a long splitting distance were successfully obtained. The high optical performance is applicable to functional devices integrated into fibers or planar waveguides.

Liquid chromatography of guanidino compounds using a porous graphite carbon column and application to their analysis in serum

The retention mechanism of guanidino compounds on a porous graphitic carbon seemed to be mainly hydrophobic interaction, according to the retention factors in buffer solutions and the results of an analysis by computational chemical calculation using molecular mechanics (MM2). The baseline separation of ten guanidino compounds was achieved by the addition of a hydrophobic counterion. The retention mechanism may be dynamic ion-exchange. The stable system was applied to the analysis of guanidino compounds in serum from nephritic patients. The effluent was monitored by a post-column labeling detection method using ninhydrin. The detection limit of guanidino compounds was a few picomoles; however, that of creatinine was one hundredth of those of the other compounds. The reproducibilities of the peak height and area of the ten guanidino compounds using gradient elution were quite high, and the standard deviations were within a few percent (n=5), except for creatinine. The recovery of the compounds from serum was more than 90% (n=5). The reproducibility of retention times was within 1% (n=5).

Residues at the subunit interfaces of the nicotinic acetylcholine receptor that contribute to alpha-conotoxin M1 binding

The two binding sites in the pentameric nicotinic acetylcholine receptor of subunit composition alpha2 beta gamma delta are formed by nonequivalent alpha-gamma and alpha-delta subunit interfaces, which produce site selectivity in the binding of agonists and antagonists. We show by sedimentation analysis that 125I-alpha-conotoxin M1 binds with high affinity to the alpha-delta subunit dimers, but not to alpha-gamma dimers, nor to alpha, gamma, and delta monomers, a finding consistent with alpha-conotoxin M1 selectivity for the alpha delta interface in the intact receptor measured by competition against alpha-bungarotoxin binding. We also extend previous identification of alpha-conotoxin M1 determinants in the gamma and delta subunits to the alpha subunit interface by mutagenesis of conserved residues in the alpha subunit. Most mutations of the alpha subunit affect affinity similarly at the two sites, but Tyr93Phe, Val188Lys, Tyr190Thr, Tyr198Thr, and Asp152Asn affect affinity in a site-selective manner. Mutant cycle analysis reveals only weak or no interactions between mutant alpha and non-alpha subunits, indicating that side chains of the alpha subunit do not interact with those of the gamma or delta subunits in stabilizing alpha-conotoxin M1. The overall findings suggest different binding configurations of alpha-conotoxin M1 at the alpha-delta and alpha-gamma binding interfaces.