Visualization of Modified Bisarylbutadiyne-Tagged Small Molecules in Live-Cell Nuclei by Stimulated Raman Scattering Microscopy

Visualizing the distribution of small-molecule drugs in living cells is an important strategy for developing specific, effective, and minimally toxic drugs. As an alternative to fluorescence imaging using bulky fluorophores or cell fixation, stimulated Raman scattering (SRS) imaging combined with bisarylbutadiyne (BADY) tagging enables the observation of small molecules closer to their native intracellular state. However, there is evidence that the physicochemical properties of BADY-tagged analogues of small-molecule drugs differ significantly from those of their parent drugs, potentially affecting their intracellular distribution. Herein, we developed a modified BADY to reduce deviations in physicochemical properties (in particular, lipophilicity and membrane permeability) between tagged and parent drugs, while maintaining high Raman activity in live-cell SRS imaging. We highlight the practical application of this approach by revealing the nuclear distribution of a modified BADY-tagged analogue of JQ1, a bromodomain and extra-terminal motif inhibitor with applications in targeted cancer therapy, in living HeLa cells. The modified BADY, methoxypyridazyl pyrimidyl butadiyne (MPDY), revealed intranuclear JQ1, while BADY-tagged JQ1 did not show a clear nuclear signal. We anticipate that the present approach combining MPDY tagging with live-cell SRS imaging provides important insight into the behavior of intracellular drugs and represents a promising avenue for improving drug development.

The effectiveness of fascial closure with antimicrobial-coated sutures in preventing incisional surgical site infections in gastrointestinal surgery: a systematic review and meta-analysis

The aim of this study was to conduct a systematic review and meta-analysis of the efficacy of fascial closure using antimicrobial-sutures specifically for the prevention of surgical site infections (SSIs) in gastrointestinal surgery, as part of the revision of the SSI prevention guidelines of the Japanese Society of Surgical Infectious Diseases (JSSI). We searched CENTRAL, PubMed and ICHUSHI-Web in May 2023, and included randomized controlled trials (RCTs) comparing antimicrobial-coated and non-coated sutures for fascial closure in gastrointestinal surgery (PROSPERO No. CRD42023430377). Three authors independently screened the RCTs. We assessed the risk of bias and the GRADE criteria for the extracted data. The primary outcome was incisional SSI and the secondary outcomes were abdominal wall dehiscence and the length of postoperative hospital stay. This study was supported partially by the JSSI. A total of 10 RCTs and 5396 patients were included. The use of antimicrobial-coated sutures significantly lowered the risk of incisional SSIs compared with non-coated suture (risk ratio: 0.79, 95% confidence intervals: 0.64-0.98). In subgroup analyses, antimicrobial-coated sutures reduced the risk of SSIs for open surgeries, and when monofilament sutures were used. Antimicrobial-coated sutures did not reduce the incidence of abdominal wall dehiscence and the length of hospital stay compared with non-coated sutures. The certainty of the evidence was rated as moderate according to the GRADE criteria, because of risk of bias. In conclusion, the use of antimicrobial-coated sutures for fascial closure in gastrointestinal surgery is associated with a significantly lower risk of SSI than non-coated sutures.

Super-resolution vibrational imaging based on photoswitchable Raman probe

Super-resolution vibrational microscopy is promising to increase the degree of multiplexing of nanometer-scale biological imaging because of the narrower spectral linewidth of molecular vibration compared to fluorescence. However, current techniques of super-resolution vibrational microscopy suffer from various limitations including the need for cell fixation, high power loading, or complicated detection schemes. Here, we present reversible saturable optical Raman transitions (RESORT) microscopy, which overcomes these limitations by using photoswitchable stimulated Raman scattering (SRS). We first describe a bright photoswitchable Raman probe (DAE620) and validate its signal activation and depletion characteristics when exposed to low-power (microwatt level) continuous-wave laser light. By harnessing the SRS signal depletion of DAE620 through a donut-shaped beam, we demonstrate super-resolution vibrational imaging of mammalian cells with excellent chemical specificity and spatial resolution beyond the optical diffraction limit. Our results indicate RESORT microscopy to be an effective tool with high potential for multiplexed super-resolution imaging of live cells.

Three-Dimensional Analysis of Water Dynamics in Human Skin by Stimulated Raman Scattering

The stratum corneum (SC), the outermost layer of the skin, has an important function to provide a barrier against dry environments. To evaluate the barrier function and the skin condition, it is crucial to investigate the ability of SC to absorb and retain water. In this study, we demonstrate stimulated Raman scattering (SRS) imaging of three-dimensional SC structure and water distribution when water is absorbed into dried SC sheets. Our results show that the process of water absorption and retention is dependent on the specific sample and can be spatially heterogeneous. We also found that acetone treatment leads to spatially homogeneous retention of water. These results suggest the great potential of SRS imaging in diagnosing skin conditions.

Activatable Raman Probes Utilizing Enzyme-Induced Aggregate Formation for Selective Ex Vivo Imaging

Detecting multiple enzyme activities simultaneously with high spatial specificity is a promising strategy to investigate complex biological phenomena, and Raman imaging would be an excellent tool for this purpose due to its high multiplexing capabilities. We previously developed activatable Raman probes based on 9CN-pyronins, but specific visualization of cells with target enzyme activities proved difficult due to leakage of the hydrolysis products from the target cells after activation. Here, focusing on rhodol bearing a nitrile group at the position of 9 (9CN-rhodol), we established a novel mechanism for Raman signal activation based on a combination of aggregate formation (to increase local dye concentration) and the resonant Raman effect along with the bathochromic shift of the absorption, and utilized it to develop Raman probes. We selected the 9CN-rhodol derivative 9CN-JCR as offering a suitable combination of increased stimulated Raman scattering (SRS) signal intensity and high aggregate-forming ability, resulting in good retention in target cells after probe activation. By using isotope-edited 9CN-JCR-based probes, we could simultaneously detect β-galactosidase, γ-glutamyl transpeptidase, and dipeptidyl peptidase-4 activities in live cultured cells and distinguish cell regions expressing target enzyme activity in Drosophila wing disc and fat body ex vivo.

Imaging the uptake of deuterated methionine in Drosophila with stimulated Raman scattering

Introduction: Visualizing small individual biomolecules at subcellular resolution in live cells and tissues can provide valuable insights into metabolic activity in heterogeneous cells, but is challenging.

Methods: Here, we used stimulated Raman scattering (SRS) microscopy to image deuterated methionine (d-Met) incorporated into Drosophila tissues in vivo.

Results: Our results demonstrate that SRS can detect a range of previously uncharacterized cell-to-cell differences in d-Met distribution within a tissue at the subcellular level.

Discussion: These results demonstrate the potential of SRS microscopy for metabolic imaging of less abundant but important amino acids such as methionine in tissue.

Quantum-enhanced stimulated Raman scattering microscopy in a high-power regime

Quantum-enhanced stimulated Raman scattering (QESRS) microscopy is expected to realize molecular vibrational imaging with sub-shot-noise sensitivity, so that weak signals buried in the laser shot noise can be uncovered. Nevertheless, the sensitivity of previous QESRS did not exceed that of state-of-the-art stimulated Raman scattering (SOA-SRS) microscopes mainly because of the low optical power (3 mW) of amplitude squeezed light [Nature594, 201 (2021)10.1038/s41586-021-03528-w]. Here, we present QESRS based on quantum-enhanced balanced detection (QE-BD). This method allows us to operate QESRS in a high-power regime (>30 mW) that is comparable to SOA-SRS microscopes, at the expense of 3 dB sensitivity drawback due to balanced detection. We demonstrate QESRS imaging with 2.89 dB noise reduction compared with classical balanced detection scheme. The present demonstration confirms that QESRS with QE-BD can work in the high-power regime, and paves the way for breaking the sensitivity of SOA-SRS microscopes.

Applications of second harmonic generation (SHG)/sum-frequency generation (SFG) imaging for biophysical characterization of the plasma membrane

The plasma membrane is a lipid bilayer of < 10 nm width that separates intra- and extra-cellular environments and serves as the site of cell-cell communication, as well as communication between cells and the extracellular environment. As such, biophysical phenomena at and around the plasma membrane play key roles in determining cellular physiology and pathophysiology. Thus, the selective visualization and characterization of the plasma membrane are crucial aspects of research in wide areas of biology and medicine. However, the specific characterization of the plasma membrane has been a challenge using conventional imaging techniques, which are unable to effectively distinguish between signals arising from the plasma membrane and those from intracellular lipid structures. In this regard, interface-specific second harmonic generation (SHG) and sum-frequency generation (SFG) imaging demonstrate great potential. When combined with exogenous SHG/SFG active dyes, SHG/SFG can specifically highlight the plasma membrane as the most prominent interface associated with cells. Furthermore, SHG/SFG imaging can be readily extended to multimodal multiphoton microscopy with simultaneous occurrence of other multiphoton phenomena, including multiphoton excitation and coherent Raman scattering, which shed light on the biophysical properties of the plasma membrane from different perspectives. Here, we review traditional and current applications, as well as the prospects of long-known but unexplored SHG/SFG imaging techniques in biophysics, with special focus on their use in the biophysical characterization of the plasma membrane.

Multimodal Multiphoton Imaging of the Lipid Bilayer by Dye-Based Sum-Frequency Generation and Coherent Anti-Stokes Raman Scattering

Coherent anti-Stokes Raman scattering (CARS) imaging is widely used for imaging molecular vibrations inside cells and tissues. Lipid bilayers are potential analytes for CARS imaging due to their abundant CH₂ vibrational bonds. However, identifying the plasma membrane is challenging since it possesses a thin structure and is closely apposed to lipid structures inside the cells. Since the plasma membrane provides the most prominent asymmetric location within cells, orientation sensitive sum-frequency generation (SFG) imaging is a promising technique for selective visualization of the plasma membrane labeled by a nonfluorescent and SFG-specific dye, Ap3, when using a CARS microscope system. In this study, we closely compare the characteristics of lipid bilayer imaging by dye-based SFG and CARS using giant vesicles (GVs) and N27 rat dopaminergic neural cells. As a result, we show that CARS imaging can be exploited for the visualization of whole lipid structures inside GVs and cells but is insufficient for identification of the plasma membrane, which instead can be achieved using dye-based SFG imaging. In addition, we demonstrate that these unique properties can be combined and applied to the live-cell tracking of intracellular lipid structures such as lipid droplets beneath the plasma membrane. Thus, multimodal multiphoton imaging through a combination of dye-based SFG and CARS can serve as a powerful chemical imaging tool to investigate lipid bilayers in GVs and living cells.

Monitoring the morphological evolution of giant vesicles by azo dye-based sum-frequency generation (SFG) microscopy

In the present work, dye-based sum-frequency generation (SFG) imaging using sodium 4-[4-(dibutylamino)phenylazo]benzenesulfonate (butyl orange, BO) as a new non-fluorescent specific azo dye is employed to monitor the morphological evolution of giant vesicles (GVs). After loading BO to the membrane of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) single-component GVs, the outermost membranes were clearly visualized using SFG microscopy, which provided images of the distinct outer and inner faces of the lipid bilayers. In addition, SFG-active vesicles were detected also inside the GVs, depending on the dye concentrations. The dye-based SFG imaging technique provided experimental evidence that these oligolamellar vesicles containing an SFG-active interior had been formed after BO loading. The formation process of the oligolamellar vesicles with inner SFG-active vesicles was successfully monitored, and their formation mechanism was discussed.

Electro-osmotic trapping and compression of single DNA molecules while passing through a nanopore

Complicated DNA molecular behaviors exist during translocation into a nanopore because their large and coiled structure needs to unwind.

High-Resolution Plasma Membrane-Selective Imaging by Second Harmonic Generation

The plasma membrane is the site of intercellular communication and subsequent intracellular signal transduction. The specific visualization of the plasma membrane in living cells, however, is difficult using fluorescence-based techniques owing to the high background signals from intracellular organelles. In this study, we show that second harmonic generation (SHG) is a high-resolution plasma membrane-selective imaging technique that enables multifaceted investigations of the plasma membrane. In contrast to fluorescence imaging, SHG specifically visualizes the plasma membrane at locations that are not attached to artificial substrates and allows high-resolution imaging because of its subresolution nature. These properties were exploited to measure the distances from the plasma membrane to subcortical actin and tubulin fibers, revealing the precise cytoskeletal organization beneath the plasma membrane. Thus, SHG imaging enables the specific visualization of phenomena at the plasma membrane with unprecedented precision and versatility and should facilitate cell biology research focused on the plasma membrane.

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Dye-based SHG imaging can specifically visualize the plasma membrane

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SHG imaging can identify the location of the plasma membrane with high precision

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Multimodal imaging reveals the precise organization of subcortical cytoskeletons

Detection of copy number variations in epilepsy using exome data

Epilepsies are common neurological disorders and genetic factors contribute to their pathogenesis. Copy number variations (CNVs) are increasingly recognized as an important etiology of many human diseases including epilepsy. Whole-exome sequencing (WES) is becoming a standard tool for detecting pathogenic mutations and has recently been applied to detecting CNVs. Here, we analyzed 294 families with epilepsy using WES, and focused on 168 families with no causative single nucleotide variants in known epilepsy-associated genes to further validate CNVs using 2 different CNV detection tools using WES data. We confirmed 18 pathogenic CNVs, and 2 deletions and 2 duplications at chr15q11.2 of clinically unknown significance. Of note, we were able to identify small CNVs less than 10 kb in size, which might be difficult to detect by conventional microarray. We revealed 2 cases with pathogenic CNVs that one of the 2 CNV detection tools failed to find, suggesting that using different CNV tools is recommended to increase diagnostic yield. Considering a relatively high discovery rate of CNVs (18 out of 168 families, 10.7%) and successful detection of CNV with <10 kb in size, CNV detection by WES may be able to surrogate, or at least complement, conventional microarray analysis.

A novel missense mutation affecting the same amino acid as the recurrent PACS1 mutation in Schuurs-Hoeijmakers syndrome

A novel causative variant (c.608G>A, p.Arg203Gln) in PACS1.

Novel biallelic SZT2 mutations in 3 cases of early-onset epileptic encephalopathy

The seizure threshold 2 (SZT2) gene encodes a large, highly conserved protein that is associated with epileptogenesis. In mice, Szt2 is abundantly expressed in the central nervous system. Recently, biallelic SZT2 mutations were found in 7 patients (from 5 families) presenting with epileptic encephalopathy with dysmorphic features and/or non-syndromic intellectual disabilities. In this study, we identified by whole-exome sequencing compound heterozygous SZT2 mutations in 3 patients with early-onset epileptic encephalopathies. Six novel SZT2 mutations were found, including 3 truncating, 1 splice site and 2 missense mutations. The splice-site mutation resulted in skipping of exon 20 and was associated with a premature stop codon. All individuals presented with seizures, severe developmental delay and intellectual disabilities with high variability. Brain MRIs revealed a characteristic thick and short corpus callosum or a persistent cavum septum pellucidum in each of the 2 cases. Interestingly, in the third case, born to consanguineous parents, had unexpected compound heterozygous missense mutations. She showed microcephaly despite the other case and previous ones presenting with macrocephaly, suggesting that SZT2 mutations might affect head size.

A case of atypical Kabuki syndrome arising from a novel missense variant in HNRNPK

A novel causative variant (c. 464T>C, p.Leu155Pro) in the heterogeneous nuclear ribonucleoprotein K (HNRNPK) gene.

Asialoglycoprotein receptor scintigraphy with 99mTc-galactosyl human serum albumin (99mTc-GSA) as an early predictor of survival in acute liver failure

This study evaluated the usefulness of asialoglycoprotein receptor scintigraphy with 99mTc-galactosyl human serum albumin (99mTc-GSA scintigraphy) as an early predictor for prognosis of acute liver failure. Forty-eight patients with acute liver failure and without a past history of chronic liver disease were enrolled. Patients were divided into survival and non-survival groups by 28-day mortality. 99mTc-GSA scintigraphy to detect uptake ratio of the heart at 15 minutes to that at three minutes (HH15) and uptake ratio of the liver at 15 minutes to the liver plus the heart at 15 minutes (LHL15), and measurements of serum total bilirubin, hepatocyte growth factor and prothrombin time were performed immediately after the diagnosis of acute liver failure. Areas under the receiver operating characteristic curves were used to compare the prognostic ability of total bilirubin, hepatocyte growth factor, prothrombin time, HH15 ratio, LHL15 ratio and the model for end-stage liver disease score. Clinical characteristics of patients in the survival group (n=20) and in the non-survival group (n=28) were not significantly different. HH15 and LHL15 uptake ratios in the survival group were 0.670 and 0.875, and they were significantly lower and higher than those in the non-survival group, respectively. All patients with LHL15 <0.760 died, and the area under the receiver operating characteristic curve for LHL15 were significantly larger than the areas under the receiver operating characteristic curves of serum variables and model for end-stage liver disease score. In summary, in patients with acute liver failure without chronic liver disease, HH15 and LHL15 of 99mTc-GSA scintigraphy are more useful variables in predicting prognosis than serum variables and model for end-stage liver disease score.

Identification of independent APP locus duplication in Japanese patients with early-onset Alzheimer disease

BACKGROUND

The occurrence of duplications of the amyloid precursor protein gene (APP) has been described in European families with early-onset familial Alzheimer disease (EO-FAD) and cerebral amyloid angiopathy. However, the contribution of APP duplication to the development of AD in other ethnic populations remains undetermined.

METHODS

The occurrence of APP duplication in probands from 25 families with FAD and 11 sporadic EO-AD cases in the Japanese population was examined by quantitative PCR and microarray-based comparative genomic hybridisation analyses. APP expression level was determined by real-time quantitative reverse-transcription (RT) PCR analysis using mRNA extracted from the peripheral blood of the patients.

RESULTS

We identified APP locus duplications in two unrelated EO-FAD families. The duplicated genomic regions in two patients of these families differed from each other. No APP duplication was found in the late-onset FAD families or sporadic EO-AD patients. The patients with APP duplication developed insidious memory disturbance in their fifties without intracerebral haemorrhage and epilepsy. Quantitative RT-PCR analysis showed the increased APP mRNA expression levels in these patients compared with those in age- and sex-matched controls.

CONCLUSIONS

Our results suggest that APP duplication should be considered in patients with EO-FAD in various ethnic groups, and that increased APP mRNA expression level owing to APP duplication contributes to AD development.

Portal blood flow regulates volume recovery of the rat liver after partial hepatectomy: molecular evaluation

BACKGROUND/AIM

Liver regeneration is a finely tuned process that is closely regulated by multiple cell cycle steps. Although the portal blood flow affects liver regeneration, the molecular mechanism by which the blood flow regulates gene expression and liver function is largely unknown. The aim of this study was to investigate the molecular effect of portal blood flow on hepatocyte proliferation and gene regulation during liver regeneration.

MATERIALS AND METHODS

We developed a simple surgical rat model to investigate the relation between portal blood flow and liver regeneration by partially ligating the portal trunk with 8-0 Proline sutures under microscopy to reduce the blood flow by 40%. We investigated recovery of liver volume, DNA synthesis, and gene expression associated with cell cycle regulators, comparing partially hepatectomized (PH) rats without (PH group; n = 30) and with partial portal ligation (PHPL group; n = 30) for 7 days after the operation.

RESULTS

The hepatic tissue blood flow and the recovery ratio between liver weight and body weight in the PHPL group were significantly lower than in the PH group after hepatectomy. The peak 5-bromo-2'-deoxyuridine labeling index in the PHPL group was delayed and weak compared with the PH group. The expression of CT-1 and cyclin D, E, and B mRNAs indicated that the liver regeneration in the PHPL group was delayed and weak. In addition, there was reciprocal expression of C/EBPalpha and C/EBPbeta mRNAs, an observation supported by their nuclear protein levels. Furthermore, the cytochrome P-450 protein level in the PHPL group was higher than that in the PH group 1 day after hepatectomy.

CONCLUSION

The portal blood flow regulates the activity of liver regeneration and the gene expression associated with cell cycle regulators, while the functions are maintained.

Acute fatty liver of pregnancy complicated with anterior pituitary insufficiency

Acute fatty liver of pregnancy complicated with anterior pituitary insufficiency in a 24-year-old nullipara woman who presented fever and progressing liver damage after the delivery by Cesarean section is described. The liver biopsy revealed severe fatty changes with microvesicular fat drops in the hepatocytes. Serum growth hormone and adrenocorticotropic hormone levels were low, and did not respond to the stimulation. The daily urinary excretion of 17-hydroxycorticosteroid was also low. Acute fatty liver of pregnancy and antehypophyseal insufficiency were diagnosed. Secondary adrenal failure was also suspected. The co-existing hypercoagulable state could cause an ischemic attack on the pituitary gland.

Pressure distribution measurement in biting surimi gels with molars using a multiple-point sheet sensor

The bite force of three surimi gels with molars was measured in the mouth using a multiple-point sheet sensor. A peak force appeared at the breaking point of each sample, and then the force increased again, accompanied by a decrease in the opening between the upper and lower teeth. Low values in the peak force, pressure, and time at the first peak, the time at which the maximum contact area was engaged, impulse, and slope of bite curve were observed in samples with low breaking force and low breaking deformation found by the mechanical measurement of gel strength, and with less toughness in the sensory assessment. The duration of the bite force, the second peak time, and active bite pressure at the second peak did not change with a change in the surimi texture. The active pressure at the breaking point of each gel was affected by gel strength, while that at the second peak was independent of the gel strength.

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.

Regulation of c-met expression in rats with acute hepatic failure

BACKGROUND

Earlier we described a model of fulminant hepatic failure (FHF) in the rat where partial hepatectomy is combined with induction of right liver lobe necrosis. In FHF rats, lack of hepatocyte proliferation was associated with delayed expression of HGF and HGF receptor c-met. Since the c-met promoter region has Sp1 binding sites, we decided to examine whether in FHF rats down-regulation of c-met is associated with decreased Sp1 function and whether changes in blood HGF, IL-6, and TGFbeta1 levels might be responsible for these effects.

MATERIALS AND METHODS

Induction of FHF, partial (2/3) hepatectomy (PH), and sham hepatectomy (SH) was performed in adult Sprague-Dawley rats. The levels of c-met mRNA and Sp1 DNA binding activity were studied in rat liver remnants at different time points after surgery. Blood levels of HGF, IL-6, and TGFbeta1 were also measured in these rats. Additionally, the effects of treatment with TGF-beta1, IL-6, or a combination of both on c-met expression and Sp1 DNA binding were studied in HGF-induced rat hepatocyte cultures.

RESULTS

Compared to SH rats, in PH rat livers c-met was up-regulated after 6 h and Sp1 DNA binding was at or only slightly lower than levels at all time points studied. In FHF rat livers, c-met expression was markedly reduced after 2 and 6 h, moderate after 12 h, and undetectable after 24 h. At the same time, Sp1 DNA binding was detected at 2 h postinduction only. In FHF rats, blood levels of all three cytokines showed early and sustained elevation. In vitro, IL-6 had no effect on c-met expression, whereas TGFbeta1 up-regulated c-met. When used alone, none of the cytokines affected Sp1 DNA binding activity. In contrast, a combination of IL-6 and TGFbeta1 down-regulated c-met expression as well as Sp1 DNA binding activity. These effects were dependent on the IL-6 concentration used. This study suggests that following massive loss of hepatocyte mass in rats, early increase in blood IL-6 and TGFbeta1 levels may weaken the expression of HGF receptor c-met in surviving hepatocytes through suppression of Sp1 DNA binding.

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.

Paper is a compatible bed for rat hepatocytes

To develop an effective hybrid bioartificial liver (BAL) device, the material of the scaffold is very important to support hepatocytes that have both growth ability and hepatic differentiated functions. In this study we used paper (Kimwipe, Kimberly-Clark Corp., Roswell, GA, U.S.A.) as a scaffold. Primary hepatocytes isolated from a normal adult rat liver could proliferate on the paper. The secretion of albumin into culture medium by the cells on the paper increased with time in culture and, compared to the cells on dishes, the amount of 48 h albumin secretion at Day 10 was two times larger. Perpendicular sections of hepatocytes on the paper revealed that the cells fell into cavities made by intersecting fibers, piled up, and formed three to four layers. The piled-up cells changed their shape from flat to cuboidal and enlarged their cytoplasm, which was rich in organelles such as mitochondria and peroxisomes with a nucleoid. In addition, they formed bile canalicular structures between the cells. Their morphological appearance was similar to in vivo hepatocytes. Paper (Kimwipe) may be a good candidate as a scaffold to make a BAL device.

Effects of nicotinamide-related agents on the growth of primary rat hepatocytes and formation of small hepatocyte colonies

AIMS/BACKGROUND

We report in this study that, 10 mM nicotinamide can stimulate the proliferation of primary rat hepatocytes in serum-free Dulbecco's modified Eagle's medium supplemented with 10 ng/ml epidermal growth factor and that small hepatocyte colonies appear from 4 to 5 days after plating. We examined the effects of nicotinamide-related agents on the growth and differentiation of primary rat hepatocytes and on the appearance of small hepatocyte colonies.

METHODS

As nicotinamide is an aqueous vitamin named niacin and known to act as an inhibitor of poly (ADP-ribose) polymerase (PARP), we therefore chose to examine the effects on hepatocytes of three nicotinamide-related agents, nicotinic acid (NA) which is also a niacin, 3-aminobenzamide (3-AB) which is a strong inhibitor of PARP but is not a niacin, and 3-acetylpyridine (3-AP) which is a weak inhibitor of PARP and also not a niacin. To examine their effects on the growth of the cells and on the formation of the colony, immunocytochemistry for BrdU was carried out. Expression of albumin, tryptophan 2,3-dioxygenase (TO), and connexin 32 (Cx32) mRNAs were used as marks of hepatic differentiation. Intracellular NAD+ content was also measured.

RESULTS

At concentration of 10 mM, NA could not enhance the proliferation of mature hepatocytes but induced the appearance of small hepatocyte colonies. At concentration of 5 mM, 3-AB enhanced the proliferation of the hepatocytes but did not induce small hepatocyte colonies. On the other hand, although 10 mM 3-AP remarkably inhibited the DNA synthesis of the cells, the expression not only of albumin but also of TO and Cx32 mRNAs in the cells was well maintained for more than one week. The intracellular NAD+ concentration was correlated with the proliferation of the hepatocytes.

CONCLUSION

These results suggest that the intracellular NAD+ content may be correlated with the proliferation of primary hepatocytes and that the supplementation of niacin in the medium may be important for the appearance of small hepatocyte colonies.

Nisin production by a mixed-culture system consisting of Lactococcus lactis and Kluyveromyces marxianus

To control the pH during antimicrobial peptide (nisin) production by a lactic acid bacterium, Lactococcus lactis subsp. lactis (ATCC11454), a novel method involving neither addition of alkali nor a separation system such as a ceramic membrane filter and electrodialyzer was developed. A mixed culture of L. lactis and Kluyveromyces marxianus, which was isolated from kefir grains, was utilized in the developed system. The interaction between lactate production by L. lactis and its assimilation by K. marxianus was used to control the pH. To utilize the interaction of these microorganisms to maintain high-level production of nisin, the kinetics of growth of, and production of lactate, acetate, and nisin by, L. lactis were investigated. The kinetics of growth of and lactic acid consumption by K. marxianus were also investigated. Because the pH of the medium could be controlled by the lactate consumption of K. marxianus and the specific lactate consumption rate of K. marxianus could be controlled by changing the dissolved oxygen (DO) concentration, a cascade pH controller coupled with DO control was developed. As a result, the pH was kept constant because the lactate level was kept low and nisin accumulated in the medium to a high level compared with that attained using other pH control strategies, such as with processes lacking pH control and those in which pH is controlled by addition of alkali.

Reconstruction of hepatic organoid by rat small hepatocytes and hepatic nonparenchymal cells

Hepatic cells isolated from an adult rat liver, consisting of small hepatocytes (SHs), mature hepatocytes (MHs), liver epithelial cells (LECs), Kupffer cells, sinusoidal endothelial cells, and stellate cells, were cultured in a medium supplemented with 10% fetal bovine serum, 10 mmol/L nicotinamide, 1 mmol/L ascorbic acid 2-phosphate, 10 ng/mL epidermal growth factor, and 1% dimethyl sulfoxide. The SHs rapidly proliferated and formed a colony. About 10% of cytokeratin 8 (CK8)-positive cells formed SH colonies. All SHs at day 10 immunocytochemically showed positivity for albumin, transferrin, CK8, and CK18, which are markers for hepatocytes. In contrast, alpha-fetoprotein (AFP)-, CK14-, OC2-, and glutathione S-transferase placental type (GST-P)-positive cells, which are thought to be markers for hepatic immature cells, were rarely observed. At day 20 some cells in the colonies were positive for AFP, CK7, CK19, and GST-P. LECs and stellate cells proliferated and surrounded the colonies. About 2 weeks after plating, piled up cells were often observed on the SH colonies. In those colonies LECs and stellate cells invaded under the colonies. The invasion of the cells and gradual deposits of extracellular matrix (ECM) such as type I collagen, type IV collagen, and laminin induced alteration of the shape of the SHs from relatively flat to cuboidal or rectangular. With the cellular structural changes, the expression of albumin, connexin 32 (Cx32), and tryptophan 2,3-dioxygenase (TO) messenger RNAs increased. In addition, overlapping nonparenchymal cells (NPCs) on the piled up cells induced the formation of duct- or cyst-like structures consisting of MHs. In the present experiment we showed that SHs could differentiate to MHs by interacting with NPCs and ECM. Thus, SHs may be "committed progenitor cells" that can further differentiate into MHs.

Growth and maturation of small hepatocytes

Proliferation of adult rat hepatocytes is observed in serum-free Dulbecco's modified Eagle's medium (DMEM) supplemented with 10 mmol/L nicotinamide and 10 ng/mL epidermal growth factor (EGF). The proliferating cells are mainly mononucleate and form small cell colonies surrounded by mature hepatocytes. Although these cells in focal colonies have a less-differentiated appearance, immunocytochemically and ultrastructurally they possess hepatic characteristics. The size of small hepatocytes is one-third to half that of mature hepatocytes. Therefore, we call the cells forming a colony, small hepatocytes. The small hepatocytes can be subcultured for several passages. Furthermore, the cells are rich in the supernatant following 50 g centrifugation for 1 min after collagenase liver perfusion. When the cells are cultured in DMEM supplemented with 10% foetal bovine serum, 10 mmol/L nicotinamide, 1 mmol/L ascorbic acid 2-phosphate, 10 ng/mL EGF and 1% dimethyl sulphoxide, each small hepatocyte can clonally proliferate for more than 3 months. A small hepatocyte divides to form a colony and the number of cells reaches more than 100 within 20 days. With time in culture, cells with a large cytoplasm appear within a colony. They have many mitochondria and large peroxisomes with crystalline nucleoids and are typical, mature hepatocytes. Immunoreactivity to connexin 32 and well-developed bile canaliculus structures are often observed in the cell-cell borders. Thus, we suggest that small hepatocytes may be considered to be 'committed progenitor cells' that can further differentiate into mature hepatocytes.

Alteration of expression of liver-enriched transcription factors in the transition between growth and differentiation of primary cultured rat hepatocytes

In the present study, we showed the role of the liver-enriched transcription factors in the transition during which proliferating hepatocytes become quiescent. We used primary rat hepatocytes cultured in modified L-15 medium. The cells proliferated and, after the addition of 2% dimethyl sulfoxide (DMSO) from day 4, they stopped growing and gradually differentiated. During hepatic proliferation, expression of hepatocyte nuclear factors (HNF)1alpha, HNF4, C/EBP alpha, and C/EBP beta mRNAs was depressed, whereas that of HNF3alpha and HNF3beta transcripts was enhanced. After the addition of DMSO, the expression of HNF1alpha, HNF3gamma, and HNF4 returned to the level in isolated cells and HNF1beta mRNA expression gradually increased. However, expression of C/EBP alpha and C/EBP beta mRNAs was partially recovered. The mitoinhibitory agents, IL-1beta, IL-6, TGF-beta, and activin A, were examined to determine whether they could induce differentiation of proliferating hepatocytes as shown in cells treated with DMSO. Although these factors inhibited cell growth, the cells did not differentiate. The expression pattern of HNF3gamma mRNA was quite different in the cells cultured with DMSO and those cultured with cytokines. Therefore, hepatic differentiation requires not only inhibition of DNA synthesis but also induction of appropriate transcription factors. Thus, expression of HNF3gamma, C/EBP alpha, and C/EBP beta may be necessary for hepatocytes to acquire highly differentiated functions in addition to coexpression of certain amounts of transcripts of HNF1alpha, HNF1beta, HNF3alpha, HNF3beta, and HNF4 as well as suppression of C/EBP delta.

Method for detection of epsilon-secondary structure in the precore region of human hepatitis B virus DNA using a fluorescence-based polymerase chain reaction-single-strand-conformation polymorphism technique with capillary electrophoresis

A portion of the precore region of the human hepatitis B virus (HBV) genome is the signal sequence with an epsilon secondary structure, which plays a role in the encapsidation of HBV pregenome RNA. To determine the genetic mutations which occur in the precore region of HBV, we have devised a typing method using a fluorescence-based polymerase-chain-reaction-single-strand conformation polymorphism technique with automated capillary electrophoresis (CE-FSSCP). Using the cloning sequencing method, we analyzed serum samples from 10 patients with hepatitis B, and detected three types of HBV-DNA including two mutants which are crucial to the function of the encapsidation sequence: position 1896 G (guanine) to A (adenine, stop codon), position 1899 G to A, and wild-type. We performed CE-FSSCP analysis of these three types of HBV-DNA and described conditions for determination of the mutations which play roles in the encapsidation of the HBV pregenome. The two types of epsilon mutants and wild-type DNA were identified as separate individual peaks respectively. The observed migration times of the three types of DNAs agreed fairly well with estimates obtained from total RNA secondary structure energy.

[Serum transferrin receptor level as an index of the response to erythropoietin therapy for anemia in pre-dialysis patients with chronic renal failure]

In order to reveal whether serum transferrin receptor (sTfR) can serve as an index in erythropoiesis during recombinant human erythropoietin (rHuEpo) therapy for anemia in pre-dialysis patients with chronic renal failure, we analyzed hematopoietic parameters and sTfR levels in 26 patients who were newly administered rHuEpo. sTfR was determined as sTfR transferrin complex (TRC) using the enzyme linked immunosolvent assay (ELISA) and the latex agglutination nephelometric immunoassay (LA). The therapeutic effect of rHuEpo was expressed as the change in the Ht from the start of treatment to 8 weeks later. (delta Ht). Ht, RBC and Hb levels were significantly increased at 4 and 8 weeks after initiating rHuEpo treatment. Furthermore, sTfR levels were significantly increased at 2 and 4 weeks after the start of rHuEpo treatment. Absolute changes in the sTfR level (sTfR before - sTfR after) and rates of change (absolute change/sTfR before x 100) at, 2, 4 weeks after the start of rHuEpo treatment showed a significant positive correlation with delta Ht. These results indicate that sTfR is a useful marker as an index of therapeutic effect of rHuEpo for anemia in pre-dialysis patients with chronic renal failure.

Analysis of two pharmacologically predicted endothelin B receptor subtypes by using the endothelin B receptor gene knockout mouse

1. This study was performed to clarify whether the endothelin (ET) receptor subtypes mediating two pharmacologically heterogeneous response to ETH receptor agonists in normal mice are the product(s) of a single ETB receptor gene. 2. Vasodilator responses to sarafotoxin S6c (S6c) in the thoracic aorta and contractile responses to ET-1 and IRL1620 in the stomach were examined in tissues from normal and ETB receptor gene knockout mice, in the absence and presence of an ETA receptor antagonist, BQ-123, or an ETA/ETB receptor antagonist, PD142893. 3. In the normal mouse aorta precontracted with phenylephrine, S6c (0.1-100 nM) caused concentration-dependent relaxations (pD2 = 8.4). BQ-123 had no effect on these responses. However, PD142893 almost abolished the relaxations induced by 0.1-300 nM S6c. 4. In aortae taken from ETB receptor gene knockout mice, S6c up to 1 microM failed to cause relaxations, confirming that ETB receptors are involved in mediating this response. 5. In normal mouse gastric fundus, 0.1 nM-1 microM ET-1, S6c or IRL1620 caused dose-dependent, BQ-123-insensitive contractions, which were much more resistant to PD142893 than S6c-induced relaxations of the aorta. The pD2 values for S6c in the absence and presence of PD142893 (10 microM) were 8.12 +/- 0.11 and 7.70 +/- 0.11, respectively. 6. In the gastric fundus of the ETB receptor gene knockout mouse, S6c and IRL1620 caused no contractions. ET-1 (0.1 nM-1 microM) caused contractions sensitive to both BQ-123 and PD142893, indicating that only ETA receptors mediate ET-1-induced contractions of the knockout mouse gastric fundus. 7. Since both the PD142893-sensitive vasodilator response of the aorta and the PD142893-resistant contractile response of the gastric fundus to S6c were completely absent in the ETB receptor gene knockout mouse, we conclude that the two pharmacologically heterogeneous responses to S6c are mediated by receptors derived from the same ETB receptor gene.

Heat shock protein 70 messenger RNA reflects the severity of ischemia/hypoxia-reperfusion injury in the perfused rat liver

OBJECTIVES

To determine whether ischemia-reperfusion and hypoxia-reoxygenation cause cellular damages and stress responses in an isolated perfused rat liver model. To determine whether the increased synthesis of stress protein messenger RNA reflects cellular injury.

DESIGN

Prospective, controlled study.

SETTING

Institutional laboratories.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Isolated rat livers with cell free perfusion were exposed to various periods of ischemia-reperfusion or hypoxia-reoxygenation.

MEASUREMENTS AND MAIN RESULTS

We measured hepatic oxygen consumption and alanine aminotransferase leakage from liver during perfusion. We analyzed the gene expression of heat shock protein 70, a major stress protein, of the liver by Northern blotting after perfusion. The expression of heat shock protein 70 messenger RNA augmented as the reperfusion period increased. The expression level after graded ischemia or hypoxia significantly correlated with the calculated hepatic oxygen debt (r2 = .737; p < .001; n = 21), or with the accumulated alanine aminotransferase leakage from the liver (r2 = .509; p < .001; n = 21).

CONCLUSIONS

These results suggest that the accumulation of heat shock protein 70 messenger RNA reflects the severity of ischemia-reperfusion and hypoxia-reoxygenation injuries, and that a stress response in reperfusion can be triggered without formed elements of blood.

Effects of volatile anesthetics on the calcium ionophore A23187-mediated alterations in hepatic flow and metabolism in the perfused liver in fasted rats

Alterations in intracellular calcium homeostasis have been implicated in heptic injury. Volatile anesthetics modulate the homeostasis of intracellular calcium. The effects of volatile anesthetics on the hemodynamic and metabolic alterations induced by the calcium ionophore A23187 were studied using isolated liver perfusion in fasted rats. The liver was isolated from 24 hr-fasted male Sprague-Dawley rats, and perfused through the portal vein at a constant pressure of 1.2 kPa in a recirculating perfusion-aeration system. Halothane, isoflurane and sevoflurane were administered at 2%, 3% and 4.4%, respectively. All volatile anesthetics maintained basal hepatic flow, reduced oxygen consumption, and transiently enhanced net lactate production. A23187 at initial concentrations of 0.8 to 3.2 microM decreased hepatic flow and oxygen consumption in a dose-dependent manner, and enhanced lactate production. All anesthetics significantly attenuated the decreases in hepatic flow and oxygen consumption after administration of A23187 at 1.6 microM. None of the anesthetics significantly influenced the A23187-induced enhancement of net lactate production. Volatile anesthetics may attenuate the hepatic vasoconstriction and oxygen debt induced by intracellular calcium overload.

Recovery of mRNA expression of tryptophan 2,3-dioxygenase and serine dehydratase in long-term cultures of primary rat hepatocytes

Expression of tryptophan 2,3-dioxygenase (TO) and serine dehydratase (SDH) has not previously been maintained or re-induced in long-term cultured hepatocytes. In the present study, we succeeded in inducing expression of TO and SDH mRNAs in adult rat hepatocytes cultured in serum-free L-15 medium supplemented with epidermal growth factor and 2% dimethyl sulfoxide (DMSO). After the start of culture, the expression of TO mRNA rapidly disappeared and at 96 h it was less than 10% of that at isolation. However, after the addition of 2% DMSO from 96 h, the transcript level gradually increased and reached about 40% of that of the isolated cells at day 14. In addition, the expression of TO mRNA was enhanced in cells treated with both 10(-5) M dexamethasone and 10(-7) M glucagon. In contrast, the expression of SDH mRNA decreased very rapidly and we could not detect it after 24 h of culture. Furthermore, 2% DMSO failed to induce it. However, when both 10(-5) M dexamethasone and 10(-7) M glucagon were added to the culture medium at day 9, we observed dramatic induction of SDH mRNA 24 h later. Primary hepatocytes cultured by this method could express and maintain highly differentiated hepatic functions for a long time. Thus, this in vitro system is suitable for the investigation of hepatic functions.