Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies

Background

Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies.

Methods

In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality.

Findings

Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42·4% vs 44·2%; absolute difference –1·69 [–9·58 to 6·11] p=0·67; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5–8] vs 6 [5–8] cm H₂O; p=0·0011). ICU mortality was higher in MICs than in HICs (30·5% vs 19·9%; p=0·0004; adjusted effect 16·41% [95% CI 9·52–23·52]; p<0·0001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0·80 [95% CI 0·75–0·86]; p<0·0001).

Interpretation

Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status.

Funding

No funding.

Observational Study to Assess and Predict Serious Adverse Events after Major Surgery

Many patients suffer from postoperative serious adverse events (SAEs). Here we sought to determine the incidence of SAEs, assess the accuracy of currently used scoring systems in predicting postoperative SAEs, and determine whether a combination of scoring systems would better predict postoperative SAEs. We prospectively evaluated patients who underwent major surgery. We calculated 4 scores: American Society of Anesthesiologists physical status (ASA-PS) score, the Charlson Score, the POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) score, and the Surgical Apgar Score (SAS). We assessed the occurrence of SAEs. We assessed the association between each score and SAEs. We combined these scoring systems to find the best combination to predict the occurrence of SAEs. Among 284 patients, 43 suffered SAEs. All scoring systems could predict SAEs. However, their predictive power was not high (the area under the receiver operating characteristic curves [AUROC] 0.6-0.7). A combination of the ASA-PS score and the SAS was the most predictive of postoperative SAEs (AUROC 0.714). The incidence of postoperative SAEs was 15.1 . The combination of the ASA-PS score and the SAS may be a useful tool for predicting postoperative serious adverse events after major surgery.

Bifid mandibular canal: confirmation of limited cone beam CT findings by gross anatomical and histological investigations

OBJECTIVES

The aims of this study were (1) to assess the validity of limited cone beam CT (CBCT) in detecting the distribution of bifid mandibular canals in the retromolar region by comparing its findings with those of panoramic radiography and spiral CT imaging, and (2) to confirm the contents of such canals depicted on limited CBCT images by using gross anatomical and histological methods.

METHODS

Bilateral bifid mandibular canals of a Japanese cadaver were investigated. The canals depicted on panoramic radiography, spiral CT and limited CBCT images were compared. Cross-sectional limited CBCT images of these canals were compared with gross anatomical sections of the mandible and their contents were confirmed histologically.

RESULTS

The spiral CT and limited CBCT images showed the bilateral bifid mandibular canals in the retromolar region whereas the panoramic radiographs indicated the presence of only the left bifid mandibular canal. The canal distribution was more distinct in the limited CBCT images than in the spiral CT images and the cross-sectional limited CBCT images were consistent with the gross anatomical sections. Histologically, the canals contained several nerve bundles and arteries among which the largest nerve and artery were of a similar size.

CONCLUSION

Limited CBCT is valuable for assessing the distribution of bifid mandibular canals. It is clinically significant to accurately localize a bifid mandibular canal of the retromolar region because it contains a nerve bundle and artery.

A crucial role of plasma membrane-associated sialidase in the survival of human cancer cells

Human plasma membrane-associated sialidase (NEU3), a key enzyme for ganglioside degradation, is markedly upregulated in human cancers, leading to apoptosis suppression. To define molecular mechanisms and the possible target for NEU3, its encoding gene was silenced by small interference RNA (siRNA) or overexpressed in human cells. NEU3 siRNA-induced apoptosis with no special stimuli in HeLa cells, accompanied with decreased Bcl-xL and increased mda7 and GM3 synthase mRNA levels, whereas overexpression resulted in the opposite. Carcinoma HT-29 and MCF-7 cells appeared to be similarly affected, but normal cell lines demonstrated no significant changes. NEU3 siRNA was found to inhibit and NEU3 overexpression to stimulate Ras activation with consequent influence on extracellular signal-regulated kinases and Akt. Ras activation by NEU3 was abrogated by PP2 (src inhibitor) or AG1478 (epidermal growth factor receptor (EGFR) inhibitor), and NEU3 actually enhanced EGF-stimulated tyrosine-phosphorylation of EGFR, suggesting that the upstream targets might be tyrosine kinases including src and EGFR, and the subsequent stimulation of Ras cascade leads to the inhibition of cell apoptosis. Glycolipid changes observed seemed to be one of the causes of the cell effects. NEU3 may thus be an essential gene for cancer cell survival and siRNAs targeting this protein could have utility for gene-based therapy of human cancers.

Bioassay monitoring of waste PCB samples during chemical destruction treatments

Capacitor oil samples (PCBs > 90%wt) were treated in a bench scale experiment to investigate the destruction of PCBs during chemical destruction processes (a catalytic hydrodechlorination treatment with palladium carbon and additional treatment with potassium tert-butyloxide). Using those results, this study confirmed the decrease of PCBs and other undesirable dioxin-like compounds such as PCDD/Fs in treated samples during the treatment. Dioxin-responsive chemical-activated luciferase expression (DR CALUX) AhR reporter gene bioassay was used to evaluate dioxin-like activity in the samples. During the treatment, the efficiency for PCB capacitor oil was around 99.99% or more in WHO-TEQ and CALUX-TEQ, whereas the sum of PCBs was reduced at a resulting efficiency of >99.9999%. In this study, a new cleanup procedure for separating PCBs from the mineral oil matrix was also developed for DR CALUX. The procedure consists of dimethylsulphoxide partitioning followed by silica gel-44% sulphuric acid reflux treatment and activated carbon chromatography. With the cleanup, CALUX-TEQ values were in good agreement with WHO-TEQ values and were as much as 3.3 times higher than WHO-TEQs for untreated/treated PCB-containing insulating oil samples. The DR CALUX results of mineral oil samples containing various PCB concentrations of 0.5-50 mg/kg (corresponding WHO-TEQs: 0.012-1.2 microg-TEQ/g) also correlated well with WHO-TEQs (CALUX-TEQ/WHO-TEQ ratio = 1.0-3.0), which was consistent with the theoretical quantification limit of the CALUX. These results supported the validity of the proposed clean-up method.

Alterations of muscarinic acetylcholine receptors in atypical Pick's disease without Pick bodies

BACKGROUND

Atypical Pick's disease without Pick bodies is a type of frontotemporal dementia characterised by semantic dementia and temporal dominant lobar atrophy with ubiquitinopathy. No neurochemical analyses have ever been reported in this condition.

OBJECTIVE

To investigate muscarinic acetylcholine receptors (mAchR) and their subtypes (M1-M4) in atypical Pick's disease.

SUBJECTS

Five cases of atypical Pick's disease were studied. They were compared with nine control cases, 11 cases of Alzheimer's disease, and seven cases of dementia with Lewy bodies.

METHODS

A [(3)H]quinuclidinyl benzilate (QNB) binding assay and an immunoprecipitation assay using subtype specific antisera were used.

RESULTS

The total amount of mAchR in the temporal cortex was lower in atypical Pick's disease than in controls or Alzheimer's disease cases, but there were no significant differences between the three groups in the frontal cortex. In the temporal cortex, there was a smaller proportion of M1 receptors in atypical Pick's disease than in the controls or in the patients with Alzheimer's disease and dementia with Lewy bodies. In contrast, the proportion of M2 receptor was higher in atypical Pick's disease than in the other three groups.

CONCLUSIONS

Depletion of postsynaptic cholinoreceptive neurones in the temporal cortex is more severe in atypical Pick's disease than in other neurodegenerative dementing disorders.

Distribution of m1 muscarinic acetylcholine receptors in the hippocampus of patients with Alzheimer's disease and dementia with Lewy bodies-an immunohistochemical study

Of the five subtypes (m1-m5) of muscarinic acetylcholine receptors (mAChR), the m1 subtype is the most abundant in the human cerebral cortex and hippocampus. Impairment of the muscarinic cholinergic system in the brain may cause cognitive dysfunction in patients with Alzheimer's disease (AD), and choline esterase inhibitors (ChE-I) are used to improve cognitive dysfunction. Severe impairment of the cholinergic system has also been reported in the brains of subjects with dementia with Lewy bodies (DLB). There have been a few reports about the distribution of mAChR subtypes in the human brain. In the present study, we investigated the distribution of m1 mAChR in the human hippocampus using an antibody against the m1 subtype. In the control brains, m1 immunoreactivity was observed in the apical dendrites and cell bodies of granular neurons of the dentate gyrus and pyramidal neurons of CA1-3 and the subiculum. The dendrites and the cell bodies of the pyramidal neurons in layers III and V of the parahippocampal cortex and other temporal cortices were also positive for m1 immunoreactivity. This m1 immunoreactivity was markedly reduced in AD and DLB brains.

Splenic and pulmonary metastases from renal cell carcinoma: report of a case

We report herein the case of a patient in whom pulmonary and splenic metastases from renal cell carcinoma (RCC) were successfully treated by surgical excision. A 69-year-old man who underwent left nephrectomy for RCC 17 months before was suspected to have a pulmonary metastasis based on computed tomography (CT) findings. Partial resection of the left lower lobe was performed with thoracoscopic assistance. However, 4 months later, a splenic tumor, 6 cm in diameter, was detected by CT and ultrasonography, and a splenectomy was performed. Histologically, both resected specimens were diagnosed as metastasis from RCC. A second pulmonary metastasis of the left upper lobe was resected 4 years 8 months later. The patient was in good health when last seen 11 months after his last operation. Malignant neoplasms rarely metastasize to the spleen and most cases are found at autopsy, or feature multiple distant metastases. Only four other cases of splenic metastases from RCC have been reported. The prognosis associated with splenic metastasis is favorable when only a solitary lesion exists.

Human stomach-specific gene, CA11, is down-regulated in gastric cancer

To reveal the implication in gastric cancer pathogenesis of the novel human gene referred to as CA11, which was recently isolated by a differential display technique using normal gastric mucosa and gastric cancer tissue, we examined CA11 expression in 50 primary gastric cancers and also introduced the CA11 gene into gastric cancer cells. RNA dot blot analysis against various human organs and developmental stages demonstrated that CA11 was intensively expressed especially in normal stomach tissue. Northern blot analysis showed that expression of the CA11 gene in cancer tissue was down-regulated compared with normal tissue. Semi-quantitative RT-PCR also demonstrated that CA11 gene expression was decreased in 41 out of 50 (82%) of the gastric cancer tissues, when compared with normal stomach tissues, while no relationship was found between CA11 expression and various clinicopathological characteristics including histological type, depth of invasion, lymph node metastasis, and clinical stage. Immunohistochemical analysis with anti CA11 antibody showed that CA11-positive staining was observed in the surface regions of normal gastric epithelium, but was found faintly or not at all in cancer tissues. CA11 transfected MKN28 cells also displayed a marked decrease in the number of colony formations when compared to double normal controls. These findings suggest that the loss of CA11 expression in gastric tissues may play an important role in gastric carcinogenesis.

Fungal histidine kinases

Eukaryotic cells predominantly use serine, threonine, and tyrosine phosphorylation in various intracellular signal transduction pathways. In contrast, prokaryotic organisms employ numerous "two-component" systems, in which signaling is achieved by transferring a phosphoryl group from phosphohistidine in the "sensor kinase" component to aspartate in the "response regulator" component. In the last several years, genetic screens and genome projects have identified sensor kinases and response regulators in lower eukaryotes and plants, revealing that eukaryotic organisms also make use of His-Asp phosphotransfer in a limited number of signaling pathways. Extensive studies in yeasts have demonstrated that a variation of the two-component system, a multistep "phosphorelay," is the prevailing mechanism among distantly related yeast species. In the budding yeast Saccharomyces cerevisiae, a His-Asp-His-Asp phosphorelay transmits osmotic stress signals to a mitogen-activated protein kinase (MAPK) cascade to induce adaptive responses. A phosphorelay in the fission yeast Schizosaccharomyces pombe, analogous to the S. cerevisiae phosphorelay, is responsible for MAPK activation in response to peroxide stress. Mammalian cells do not have any two-component or phosphorelay systems, although protein histidine kinases unrelated to the sensor kinase may be involved in cellular signaling. Because some phosphorelay proteins are essential for virulence of microbial pathogens, including the yeast fungus Candida albicans, novel antibiotics targeted to phosphorelays may be effective against eukaryotic pathogens without causing host cell damage.

Estrogenic and dioxin-like potency in each step of a controlled landfill leachate treatment plant in Japan

The estrogenic activity (by E-screen bioassay), the concentrations of PCBs, PCDDs/PCDFs (and their resulting toxicity equivalents, TEQ) and several endocrine disrupting chemicals (EDCs: e.g., bisphenol A, nonylphenol, Butyl benzylpthalate (BBP), di-n-butylphthalate (DBP), 17alpha-ethynyl-estradiol or 4-octylphenol) have been analyzed from leachates of each step (before treatment, after biodegradation/sedimentation and after charcoal treatment) of a controlled landfill leachate treatment plant. The comparison of the effluent of the examined landfill leachate treatment plant with water from a nearby river in this study indicated no additional dioxin-like (e.g., TEQ: 0.027 compared to 1.01 pg TEQ/l; PCBs: 1.2 compared to 3.9 ng/l) or estrogenic impact (2.8 compared to 3.5 ng estradiol equivalents EE/l; analyzed by E-screen bioassay) from the leachate treatment plant into the surrounding water environment. The impact of dioxin-like compounds from uncleaned leachates into the final cleaned effluents could be sufficiently reduced by the leachate treatment plant for PCDDs (75%), PCDFs (62%), dioxin-like PCBs (97%), and the sum of TEQ (78%). The leachate treatment plant also achieved a reduction of the estrogenic activity as determined by E-screen (from 4.8 to 2.8 ng EE/l = 42%), by GC/MS for bisphenol A (>96% and nonylphenol (>98%) or by ELISA for estradiol (>80%). Additionally, for the validation of the E-screen, five known endocrine disrupting chemicals (EDCs: bisphenol A, BBP, DBP, 17 alpha-ethynyl-estradiol, 4-octylphenol) were analyzed. The EC50 values and estradiol equivalents factors (EEFs) for the five EDCs determined in this study were comparable to previously published data. The combined biological and chemical trace analysis data have provided valuable information on the relative contribution of natural, synthetic, and non-steroidal anthropogenic chemicals to the estrogenic and dioxin-like activity in leachates from a wastewater treatment plant, and water from a nearby river.

Combustion of brominated flame retardants and behavior of its byproducts

The substance flow rate of PBDDs/DFs into flue gas and incineration residues from incineration of three types of waste samples containing brominated flame retardants were examined. The samples used consisted of PBDEs (a typical retardant), used TV casing materials (actual waste materials), and waste printed circuit boards. PBDDs/DFs concentrations in the experimental samples of PBDEs/PE, waste TV casing materials and printed circuit boards ranged between 3000 and 130,000 ng/g. These values are very high when compared to other investigations. The increase of chlorine concentration in input sample reduced the ratio of PBDDs/DFs in flue gas and raised the ratio of PCDDs/DFs. With adequate combustion control and flue gas treatment, the amount of PBDDs/DFs released from the incineration of resin containing brominated flame retardants was lower than the input amount. The presence of PBDDs/DFs in incineration residues dominated the total amount of dioxins released. When PBDDs/DFs, PCDDs/DFs and PXDDs/DFs were considered as a total, the total amount released was lower than the total amount input.

Prednisolone suppresses ischemia-reperfusion injury of the rat liver by reducing cytokine production and calpain mu activation

BACKGROUND

We investigated the effects of prednisolone on cytokine production and calpain mu activation during hepatic ischemia-reperfusion (IR) injury.

METHODS

The hilar area of the left lateral and median lobes of rat liver was clamped for 60 min. Prednisolone was administered at 1.0, 3.0, or 10 mg/kg at 30 min before ischemia. In addition to biochemical and microscopic analyses, IL-beta and TNF-alpha production was evaluated by RT-PCR. Calpain mu activation and talin degradation were determined by Western blotting, using specific antibodies.

RESULTS

In the control and prednisolone (1.0 mg/kg) groups, serum AST and ALT levels were elevated, and cell membrane bleb formation was observed after 2 h of reperfusion. Moreover, calpain mu activation, talin degradation, and overexpression of IL-beta and TNF-alpha mRNAs were detected. Infusion of prednisolone at 3.0 or 10 mg/kg significantly suppressed biochemical and microscopic changes. At 10 mg/kg, prednisolone markedly suppressed IL-beta and TNF-alpha transcription and calpain mu activation and talin degradation, consistent with the improved 7-day survival after total hepatic ischemia (75% vs. 25% in control group, P = 0.039).

CONCLUSIONS

Cytoprotective effect of prednisolone in hepatic IR injury was closely associated with suppression of IL-beta/TNF-alpha production and calpain mu activation.

Effect of Ca(2+)-independent mechanisms on the hypoxic relaxation of guinea-pig tracheal rings

Hypoxia induces bronchodilation in vivo and in vitro, but the mechanisms are still unclear. To evaluate whether an extra- or intracellular free Ca(2+) ion is involved in the mechanisms of hypoxic relaxation, we simultaneously measured cytosolic Ca(2+)levels and tensions in both intact and denuded guinea-pig tracheal strips precontracted with histamine (100 microM), and assessed the effect of hypoxia on guinea-pig tracheal rings precontracted with okadaic acid (10 microM) and calyculin-A (0.1 approximately 10 microM) under an extracellular Ca(2+)-free state. The exposure of tracheal rings to hypoxia induced an immediate decrease of tracheal tension without decrease in intracellular free Ca(2+)levels. In the presence of okadaic acid but not calyculin-A, hypoxic air exposure caused significant transient reductions in tracheal tone. Further, thapsigargin (5 microM or 10 microM) did not affect hypoxic bronchodilation, suggesting that the release of intracellular Ca(2+) does not take a role in hypoxic bronchodilation. Hypoxic dilation decreased ATP content in epithelium-intact rings but not epithelium-denuded rings, indicating a relationship between hypoxic dilation and change of adenine nucleotide in epithelium-intact rings. Our findings indicate that the epithelium dependent mechanisms of hypoxic relaxation of guinea pig tracheal rings preconstricted with histamine may not be related to the mobilization of extra and intra-cellular Ca(2+).

Outcome of pancreatic cancer patients based on genetic lymph node staging

We prospectively assessed the clinical value of genetic staging of lymph node metastasis in patients with pancreatic adenocarcinoma who underwent curative surgery. K-ras gene mutations were detected in the primary tumors in 18 of 25 patients with pancreatic adenocarcinoma. Among these 18 patients, mutated K-ras gene was also found in at least one lymph node in 13 patients. Of these 13 patients, seven had no evidence of histological nodal involvement and six had histological lymph node metastasis. Although there was no significant difference in overall survival rates between the pathological node-negative and -positive patients, overall survival of the five patients with nodes-negative for the mutated K-ras gene were significantly better than that of the 13 patients with genetically metastasis-positive nodes (p<0.001). Furthermore, overall survival of the six patients with genetically metastasis-positive nodes limited to peripancreatic area was significantly better than that of seven patients with genetical metastasis in lymph nodes beyond the peripancreatic areas (p=0.018). These findings suggest that detection of K-ras gene mutations in lymph nodes may be clinically useful to assess the accurate tumor staging and to stratify the patient with pancreatic adenocarcinoma who are at high or low risk for recurrence after curative surgery.

Multistep phosphorelay proteins transmit oxidative stress signals to the fission yeast stress-activated protein kinase

In response to oxidative stress, eukaryotic cells induce transcription of genes required for detoxification of oxidants. Here we present evidence that oxidative stress stimuli are transmitted by a multistep phosphorelay system to the Spc1/Sty1 stress-activated protein kinase in the fission yeast Schizosaccharomyces pombe. The fission yeast mpr1(+) gene encodes a novel protein with a histidine-containing phosphotransfer domain homologous to the budding yeast Ypd1. Spc1 activation upon oxidative stress is severely impaired in the Deltampr1 mutant as well as in the mpr1HQ strain, in which the putative phosphorylation site Mpr1-His221 is substituted with glutamine. In response to oxidative stress, Mpr1 binds to the Mcs4 response regulator that functions upstream of the Spc1 cascade, suggesting that Mcs4 is a cognate response regulator for Mpr1. Unexpectedly, when exposed to hydrogen peroxide, Deltampr1 cells can induce the catalase gene ctt1(+), one of the transcriptional targets of the Spc1 pathway, and survive oxidative stress in the absence of significant Spc1 activation. We have found that Pap1, a bZIP transcription factor homologous to human c-Jun, can mediate induction of ctt1(+) expression upon oxidative stress independently of the Spc1 stress-activated protein kinase. These studies show that oxidative stress stimuli are transmitted by multiple pathways to induce specific gene expression.

Assessment of Stanniocalcin-1 mRNA as a molecular marker for micrometastases of various human cancers

We assessed Stanniocalcin-1 (STC-1) mRNA expression in human normal tissues, various types of human cancer cell lines, and cancer tissues obtained during surgery. Using a reverse transcriptase-polymerase chain reaction (RT-PCR) assay developed to detect STC-1 mRNA, the transcripts were detected in 20 out of 21 cancer cell lines and in all tumor tissues from various types of cancer. Semi-quantitative analyses with multiplex RT-PCR showed that STC-1 mRNA tended to be enhanced in cancer tissues of hepatocellular carcinoma and colorectal cancer compared to background cancer-free tissues. Analysis of blood samples obtained from 11 patients with hepatocellular carcinoma before, after and during hepatectomy showed STC-1 mRNA expression in 8 out of 11 patients at least one time. Normal donor blood samples (n=31) were all-negative for STC-1 mRNA expression. Our results indicate that STC-1 mRNA might be a useful molecular marker for detection of tumor cells in blood from patients with various types of malignancies.

[Neurally mediated syncope in association with small cell lung carcinoma]

A 66-year-old woman was admitted to our hospital because of frequent syncopal episodes and for treatment of small cell lung carcinoma. Neurally mediated syncope was diagnosed by the head-up tilt test, which evoked early severe hypotension (after 12 min at the 80-degree tilt position). Treatment of carcinoma by chemotherapy and radiotherapy promptly eliminated the syncopal episodes. This was an unusual case of neurally mediated syncope associated with small cell lung carcinoma.

Alterations of muscarinic acetylcholine receptor subtypes in diffuse lewy body disease: relation to Alzheimer's disease

OBJECTIVES

Dementia associated with Lewy bodies in cortical and subcortical areas is classified as dementia of the non-Alzheimer type and termed diffuse Lewy body disease (DLBD). The generic term "dementia with Lewy bodies (DLB)" was proposed in the international workshop on Lewy body dementia to include the similar disorders presenting Lewy bodies. In DLB, a lower level of choline acetyltransferase (ChAT) activity in the neocortex was found compared with that in Alzheimer's disease. The purpose of the present study was to determine the total amount of muscarinic acetylcholine receptors (mAChRs) and relative proportion of each subtype (m1-m4) of mAChRs in the frontal and temporal cortex of seven DLBD and 11 Alzheimer's disease necropsied brains.

METHODS

A [(3)H]quinuclidinyl benzilate (QNB) binding assay and an immunoprecipitation assay using subtype-specific antibodies were performed. Each antibody was raised against fusion proteins containing peptides corresponding to the third intracellular (i3) loops of the respective mAChR subtype.

RESULTS

The total amounts of mAChRs were significantly lower in the preparations of temporal cortices from DLBD and Alzheimer's disease than in those from dead controls (seven cases). In both diseases, the proportion of the m3 receptor in the frontal cortex was significantly increased and that of the m4 receptor in the temporal cortex was significantly decreased compared with the control specimens. The proportions of the m1 and m2 subtypes were significantly different in the temporal cortex. The proportion of the m1 receptor was significantly greater in the DLBD brains, whereas that of the m2 receptor was significantly greater in the Alzheimer's disease brains than in the controls.

CONCLUSIONS

The m1 receptor is the major subtype in the cerebral cortex, and m2 is known to be present at presynaptic terminals. The higher proportions of m1 in DLBD and m2 in Alzheimer's disease suggest that the manner of degeneration in the cholinergic system is different between the diseases. It is hypothesised that a severe depletion of presynaptic cholinergic projective neurons causes the upregulation of m1 receptor in the temporal cortex in DLBD.

Heat-shock-induced activation of stress MAP kinase is regulated by threonine- and tyrosine-specific phosphatases

In eukaryotic species from yeast to human, stress-activated protein kinases (SAPKs), members of a MAP kinase (MAPK) subfamily, regulate the transcriptional response to various environmental stress. It is poorly understood how diverse forms of stress are sensed and transmitted to SAPKs. Here, we report the heat shock regulation of the fission yeast Spc1 SAPK, a homolog of human p38 and budding yeast Hog1p. Although osmostress and oxidative stress induce strong activation of the Wis1 MAPK kinase (MEK), which activates Spc1 through Thr-171/Tyr-173 phosphorylation, activation of Wis1 upon heat shock is relatively weak and transient. However, in heat-shocked cells, Pyp1, the major tyrosine phosphatase that dephosphorylates and inactivates Spc1, is inhibited for its interaction with Spc1, which leads to strong activation of Spc1. Subsequently, Spc1 activity is rapidly attenuated by Thr-171 dephosphorylation, whereas Tyr-173 remains phosphorylated. Thr-171 dephosphorylation is compromised in a strain lacking functional type 2C serine/threonine phosphatases (PP2C), Ptc1 and Ptc3. Moreover, Ptc1 and Ptc3 can dephosphorylate Thr-171 of Spc1 both in vivo and in vitro. These observations strongly suggest that PP2C enzymes play an important role in the attenuation of Spc1 activity in heat-shocked cells. Thus, transient activation of Spc1 upon heat shock is ensured by differential regulation of threonine and tyrosine phosphorylation.

Heat stress activates fission yeast Spc1/StyI MAPK by a MEKK-independent mechanism

Fission yeast Spc1/StyI MAPK is activated by many environmental insults including high osmolarity, oxidative stress, and heat shock. Spc1/StyI is activated by Wis1, a MAPK kinase (MEK), which is itself activated by Wik1/Wak1/Wis4, a MEK kinase (MEKK). Spc1/StyI is inactivated by the tyrosine phosphatases Pyp1 and Pyp2. Inhibition of Pyp1 was recently reported to play a crucial role in the oxidative stress and heat shock responses. These conclusions were based on three findings: 1) osmotic, oxidative, and heat stresses activate Spc1/StyI in wis4 cells; 2) oxidative stress and heat shock activate Spc1/StyI in cells that express Wis1AA, in which MEKK consensus phosphorylation sites were replaced with alanine; and 3) Spc1/StyI is maximally activated in Deltapyp1 cells. Contrary to these findings, we report: 1) Spc1/StyI activation by osmotic stress is greatly reduced in wis4 cells; 2) wis1-AA and Deltawis1 cells have identical phenotypes; and 3) all forms of stress activate Spc1/StyI in Deltapyp1 cells. We also report that heat shock, but not osmotic or oxidative stress, activate Spc1 in wis1-DD cells, which express Wis1 protein that has the MEKK consensus phosphorylation sites replaced with aspartic acid. Thus osmotic and oxidative stress activate Spc1/StyI by a MEKK-dependent process, whereas heat shock activates Spc1/StyI by a novel mechanism that does not require MEKK activation or Pyp1 inhibition.

Phosphorylation and association with the transcription factor Atf1 regulate localization of Spc1/Sty1 stress-activated kinase in fission yeast

Control of gene expression by stress-activated protein kinase (SAPK) cascades is crucial for combating cytotoxic stress. Elements of these cascades have been investigated in detail, but regulation of stress signal transduction from the cytoplasm to the nucleus is poorly understood. Herein are reported subcellular localization studies of fission yeast Spc1, a homolog of human p38 and budding yeast Hog1p SAPKs. Stress induces transient nuclear localization of Spc1. Nuclear translocation of Spc1 is coupled with disassociation from its activator kinase Wis1. However, Spc1 does not concentrate in the nucleus of Deltawis1 cells; therefore Wis1 does not tether Spc1 in the cytoplasm. Unphosphorylatable forms of Spc1 are dispersed in the cytoplasm and nucleus, even in cells that also produce wild-type Spc1. Thus, Spc1 must be phosphorylated by Wis1 to localize in the nucleus. Nuclear retention of Spc1 requires Atf1, a transcription factor that is the key nuclear substrate of Spc1. Nuclear localization of Atf1 requires Pcr1, a heterodimerization partner of Atf1. These studies show that phosphorylation and association with Atf1 are required for nuclear localization of Spc1.

[A case of liver metastasis of gastric leiomyosarcoma successfully treated by transarterial hepatic chemo-embolization and intra hepato-arterial chemotherapy repeated with infusion-a-port]

The patient was a 68-year-old male, who underwent total gastrectomy for giant leiomyosarcoma of the stomach and then had multiple hepatic metastases one year and six months later. Thus, transarterial hepatic chemo-embolization therapy with Lipiodol, adriamycin and gelfoam was given. Moreover, using a reservoir catheter and infusion arterial port, intermittent arterial infusion therapy with adriamycin, cyclophosphamide, and vincristine was attempted. In the metastasis lesion where there were rich blood vessels, Lipiodol was accumulated and the tumor was reduced on abdominal CT. The result indicated the efficacy of this treatment.

[Hepatic arterial chemotherapy for liver cancer over a period of 8 years]

Hepatic arterial chemotherapy was performed for 27 patients with primary (3), metastatic liver cancer (21), and 3 other cases, over a period of 8 years. Chemotherapy was performed by intermittent hepatic arterial infusion of 5-FU or FAM (in case of metastatic tumor from colorectal cancer), FAM (from gastric cancer), and CDDP or Farmorubicin (HCC). Hepatic resection was performed in 10 cases of metastatic tumor from colorectal cancer, and 8 cases of 10 were curative operation. The 5-year survival rates of curative liver resection group, and non-curative liver resection or non-resection group were 57.1% and 12.5%, respectively. As is the case with metastatic cancer from gastric cancer, pancreatic cancer, and hepatocellular carcinoma (HCC), the prognosis was poor except for one CR case of HCC. We concluded that hepatic arterial chemotherapy may be recommended for a curative resected case of liver metastasis from colorectal cancer.

Protein phosphatase 2C acts independently of stress-activated kinase cascade to regulate the stress response in fission yeast

Stress-activated signal transduction pathways, which are largely conserved among a broad spectrum of eukaryotic species, have a crucial role in the survival of many forms of stress. It is therefore important to discover how these pathways are both positively and negatively regulated. Recent genetic studies have implicated protein phosphatase 2C (PP2C) as a novel negative regulator of stress response pathways in both budding and fission yeasts. Moreover, it was hypothesized that PP2C dephosphorylates one or more components of protein kinase cascades that are at the core of stress-activated signal transduction pathways. Herein we present genetic and biochemical studies of the fission yeast Schizosaccharomyces pombe that disprove this hypothesis and indicate that PP2C instead negatively regulates a downstream element of the pathway. First, high expression of PP2C produces phenotypes that are inconsistent with negative regulation of the Wik1-Wis1-Spc1 stress-activated kinase cascade. Second, high expression of PP2C leads to sustained activating tyrosine phosphorylation of Spc1. Third, Spc1-dependent phosphorylation of Atf1, a transcription factor substrate of Spc1, is unaffected by high expression of PP2C. Fourth, high expression of PP2C suppresses Atf1-dependent transcription of a stress-response gene. These studies strongly suggest that PP2C acts downstream of Spc1 kinase in the stress-activated signal transduction pathway.

[A case of malignant hemangioendothelioma of the lung with rapid growth of pulmonary metastasis]

Malignant hemangioendothelioma of the lung is very rare and difficult to diagnose. The growth is rapid and the prognosis is very unfavorable. We report an operated case of the disease with rapid growth of pulmonary metastasis. The silver, vimentin and factor VIII stainings were available for diagnosis of this disease. The 46-year-old female patient died of bleeding from the pulmonary metastasis eight months after the operation without other distant metastasis. Even if a lung tumor is pointed out and thought to be benign, frequent follow up is necessary. Furthermore, we recommend positive lung biopsy by thoracotomy or video-assisted-thoracic-surgery.

Mcs4 mitotic catastrophe suppressor regulates the fission yeast cell cycle through the Wik1-Wis1-Spc1 kinase cascade

Spc1 in Schizosaccharomyces pombe is a member of the stress-activated protein kinase family, an evolutionary conserved subfamily of mitogen-activated protein kinases (MAPKs). Spc1 is activated by a MAPK kinase homologue, Wis1, and negatively regulated by Pyp1 and Pyp2 tyrosine phosphatases. Mutations in the spc1+ and wis1+ genes cause a G2 cell cycle delay that is exacerbated during stress. Herein, we describe two upstream regulators of the Wis1-Spc1 cascade. wik1+ (Wis1 kinase) was identified from its homology to budding yeast SSK2, which encodes a MAPKK kinase that regulates the HOG1 osmosensing pathway. Delta wik1 cells are impaired in stress-induced activation of Spc1 and show a G2 cell cycle delay and osmosensitive growth. Moreover, overproduction of a constitutively active form of Wik1 induces hyperactivation of Spc1 in wis1(+)-dependent manner, suggesting that Wik1 regulates Spc1 through activation of Wis1. A mutation of mcs4+ (mitotic catastrophe suppressor) was originally isolated as a suppressor of the mitotic catastrophe phenotype of a cdc2-3w wee1-50 double mutant. We have found that mcs4- cells are defective at activation of Spc1 in response to various forms of stress. Epistasis analysis has placed Mcs4-upstream of Wik1 in the Spc1 activation cascade. These results indicate that Mcs4 is part of a sensor system for multiple environmental signals that modulates the timing of entry into mitosis by regulating the Wik1-Wis1-Spc1 kinase cascade. Inactivation of the sensor system delays the onset of mitosis and rescues lethal premature mitosis in cdc2-3w wee1-50 cells.

Pneumonitis during interferon and/or herbal drug therapy in patients with chronic active hepatitis

We report four cases of acute pneumonitis due either to interferon, or a herbal drug, "Sho-saiko-to", or both in combination, in patients with chronic active hepatitis, focusing on its pathogenesis and response to prednisolone therapy. These cases shared common clinical features: fever, dry cough, dyspnoea, hypoxaemia, diffuse infiltrates both on chest radiography and chest computed tomography, restrictive pulmonary functional impairment, and alveolitis on examination of transbronchial lung biopsy, all of which suggest acute interstitial pneumonia. Furthermore, lymphocytosis was observed in association with the dominant CD8+ T-cell subset in bronchoalveolar lavage fluid. A lymphocyte stimulation test using peripheral blood was positive to interferon in one case and to Sho-saiko-to in another. All patients responded to oral prednisolone therapy. Peripheral soluble interleukin-2 receptor levels decreased in parallel with improvement in the clinical course. All patients were free of symptoms with a follow-up of 1-3 yrs. We conclude that interferon- and/or Sho-saiko-to-induced acute pneumonitis may be due to allergic-immunological mechanisms rather than toxicity, and that peripheral levels of soluble interleukin-2 receptor appear to be good markers of disease activity.

Spatial organization of the Nim1-Wee1-Cdc2 mitotic control network in Schizosaccharomyces pombe

In Schizosaccharomyces pombe the onset of mitosis is regulated by a network of protein kinases and phosphatases. The M-phase inducing Cdc2-Cdc13 cyclin-dependent kinase is inhibited by Wee1 tyrosine kinase and activated by Cdc25 phosphatase. Wee1 is negatively regulated by Nim1 protein kinase. Here, we describe investigations aimed at better understanding the role of Nim1 in the mitotic control. The most important finding to emerge from these studies is that Wee1 and Nim1 have different patterns of intracellular localization. Immunofluorescence confocal microscopy has revealed that Nim1 is localized in the cytoplasm, whereas it substrate Wee1 is predominantly localized in the nucleus. Previous studies showed that the Cdc2-Cdc13 complex is located in the nucleus. Diversion of Nim1 to the nucleus, accomplished by addition of the SV40 nuclear localization signal, caused the advancement of M, confirming that Nim1 has restricted access to Wee1 in vivo. We propose that the intracellular distribution of Nim1 and Wee1 may serve to coordinate the regulation of nuclear Cdc2-Cdc13 with cytoplasmic growth.

Conjugation, meiosis, and the osmotic stress response are regulated by Spc1 kinase through Atf1 transcription factor in fission yeast

The stress-activated Wis1-Spc1 protein kinase cascade links mitotic control with environmental signals in Schizosaccharomyces pombe. Fission yeast spc1- mutants are delayed in G2 during normal growth and undergo G2 arrest when exposed to osmotic or oxidative stress. Here we report that Spc1 also has an important role in regulating sexual development in S. pombe. This discovery arose from the observation that Spc1 is activated in response to nitrogen limitation, a key signal that promotes conjugation in fission yeast. Mutant spc1- cells are defective at arresting in G2 during nitrogen starvation and exhibit a poor mating ability. These deficiencies correlate with a failure to induce transcription of ste11+, a gene that encodes a transcription factor responsible for expression of various meiotic genes. Two genes, atf1+ and atf21+, were cloned as multicopy suppressors of the spc1- mating defect. Atf1 and Atf21 are bZIP transcription factors that are most closely related to human ATF-2/CRE-BP1. Spc1 is required for stress-induced phosphorylation of Atf1. Atf1 is required for induction of meiotic genes and stress-response genes, such as gpd1+ and pyp2+, that are transcriptionally regulated by Spc1. atf1- and spc1- mutants are sensitive to osmotic stress and impaired for sexual development, showing that fission yeast uses a common pathway to respond to cytotoxic stress and nitrogen starvation. However, unlike spc1- mutants, atf1- cells have no mitotic cell-cycle defect, indicating that the stress response pathway bifurcates at Spc1 to regulate independently meiosis and mitosis.

Activation and regulation of the Spc1 stress-activated protein kinase in Schizosaccharomyces pombe

Spc1, an osmotic-stress-stimulated mitogen-activated protein kinase (MAPK) homolog in the fission yeast Schizosaccharomyces pombe, is required for the induction of mitosis and survival in high-osmolarity conditions. Spc1, also known as Sty1, is activated by Wis1 MAPK kinase and inhibited by Pyp1 tyrosine phosphatase. Spc1 is most closely related to Saccharomyces cerevisiae Hog1 and mammalian p38 kinases. Whereas Hog1 is specifically responsive to osmotic stress, we report here that Spc1 is activated by multiple forms of stress, including high temperature and oxidative stress. In this regard Spc1 is more similar to mammalian p38. Activation of Spc1 is crucial for survival of various forms of stress. Spc1 regulates expression of genes encoding stress-related proteins such as glycerol-3-phosphate dehydrogenase (gpd1+) and trehalose-6-phosphate synthase (tps1+). Spc1 also promotes expression of pyp2+, which encodes a tyrosine phosphatase postulated as a negative regulator of Spc1. This proposal is supported by the finding that Spc1 associates with Pyp2 in vivo and that the amount of Spc1 tyrosine phosphorylation is lower in a Pyp2-overproducing strain than in the wild type. Moreover, the level of stress-stimulated gpd1+ expression is higher in delta pyp2 mutants than in the wild type. These findings demonstrate that Spc1 promotes expression of genes involved in stress survival and that of regulation may be commonly employed to modulate MAPK signal transduction pathways in eukaryotic species.

Phosphorylation of human m1 muscarinic acetylcholine receptors by G protein-coupled receptor kinase 2 and protein kinase C

Human muscarinic acetylcholine receptor m1 subtypes (m1 receptors) were expressed in and purified from insect Sf9 cells and then subjected to phosphorylation by G protein-coupled receptor kinase 2 (GRK2) expressed in and purified from Sf9 cells and by protein kinase C purified from rat brain (a mixture of alpha, beta, and gamma types, PKC). The m1 receptor was phosphorylated by either GRK2 or PKC in an agonist-dependent or independent manner, respectively. G protein beta gamma subunits stimulated the phosphorylation by GRK2 but did not affect the phosphorylation by PKC. The number of incorporated phosphates was 4.6 and 2.8 mol/mol of receptor for phoshorylation by GRK2 and PKC, respectively. The number of incorporated phosphates was 7.5 mol/mol receptor for phosphorylation by GRK2 followed by PKC, but was 5.8 mol/mol of receptor for the phosphorylation by PKC followed by GRK2. Major sites phosphorylated by GRK2 and PKC were located in the third intracellular loop and the carboxyl-terminal tail, respectively. These results indicate that GRK2 and PKC phosphorylate different sites of m1 receptors and that the phosphorylation by PKC partially inhibits the phosphorylation by GRK2, probably by affecting activation of GRK2 by agonist-bound receptors.

Selective Isolation of DNA or RNA Using Single-Stranded DNA Affinity Latex Particles

We developed latex particles with a diameter of about 0.22 µm on which single-stranded (ss) DNA was covalently coupled to select or enrich its complementary DNA or mRNA. DNA was first covalently coupled to the latex particles in the double-stranded (ds) form with both blunt and protruding ends. More than 80% of the dsDNA was coupled through the ssDNA stretch at its protruding end. The presence of NaCl in the immobilization reaction severely inhibited DNA from coupling to the particles. The particles were then treated with alkali or heated to denature the dsDNA and sedimented by a brief centrifugation to yield ssDNA immobilized particles. They allowed the selective and efficient isolation of a desired RNA from total cellular RNA.

Cell-cycle control linked to extracellular environment by MAP kinase pathway in fission yeast

In fission yeast the onset of mitosis is brought about by Cdc2/Cdc13 kinase, which is inhibited by the Wee1/Mik1 tyrosine kinases and activated by Cdc25 tyrosine phosphatase. This control network integrates many signals, including those that monitor DNA replication, DNA damage and cell size. We report here that a fission yeast MAP kinase pathway links the cell-cycle G2/M control with changes in the extracellular environment that affect cell physiology. Fission yeast spc1- mutants have a G2 delay that is greatly exacerbated by growth in high osmolarity media and nutrient limitation. A lethal interaction of spc1 and cdc25 mutations shows that Spc1 promotes the onset of mitosis. Spc1 is a MAP kinase homologue that is activated by Wis1 kinase in response to osmotic stress and nutrient limitation. Spc1 is inactivated by Pyp1, a phosphatase previously identified as a mitotic inhibitor. Pyp1 dephosphorylates only tyrosine-173 of Spc1, unlike the dual-specificity phosphatases that have been shown to regulate other MAP kinases.

Counteractive roles of protein phosphatase 2C (PP2C) and a MAP kinase kinase homolog in the osmoregulation of fission yeast

With the goal of discovering the cellular functions of type 2C protein phosphatases, we have cloned and analyzed two ptc (phosphatase two C) genes, ptc2+ and ptc3+, from the fission yeast Schizosaccharomyces pombe. Together with the previously identified ptc1+ gene, the enzymes encoded by these genes account for approximately 90% of the measurable PP2C activity in fission yeast cells. No obvious growth defects result from individual disruptions of ptc genes, but a delta ptc1 delta ptc3 double mutant displays aberrant cell morphology and temperature-sensitive cell lysis that is further accentuated in a delta ptc1 delta ptc2 delta ptc3 triple mutant. These phenotypes are almost completely suppressed by the presence of osmotic stabilizers, strongly indicating that PP2C has an important role in osmoregulation. Genetic suppression of delta ptc1 delta ptc3 lethality identified two loci, mutations of which render cells hypersensitive to high-osmolarity media. One locus is identical to wis1+, encoding a MAP kinase kinase (MEK) homolog. The Wis1 sequence is most closely related to the Saccharomyces cerevisiae MEK encoded by PBS2, which is required for osmoregulation. These data indicate that divergent yeasts have functionally conserved MAP kinase pathways, which are required to increase intracellular osmotic concentrations in response to osmotic stress. Moreover, our observations implicate PP2C enzymes as also having an important role in signal transduction processes involved in osmoregulation, probably acting to negatively regulate the osmosensing signal that is transmitted through Wis1 MAP kinase kinase.

Protein phosphatase 2C, encoded by ptc1+, is important in the heat shock response of Schizosaccharomyces pombe

Protein phosphatase 2C (PP2C), an Mg(2+)-dependent enzyme that dephosphorylates serine and threonine residues, defines one of the three major families of structurally unrelated eukaryotic protein phosphatases. Members of the two other families of protein phosphatases are known to have important cellular roles, but very little is known about the biological functions of PP2C. In this report we describe a genetic investigation of a PP2C enzyme in the fission yeast Schizosaccharomyces pombe. We discovered ptc1+ (phosphatase two C) as a multicopy suppressor gene of swo1-26, a temperature-sensitive mutation of a gene encoding the heat shock protein hsp90. The ptc1+ gene product is a 40-kDa protein with approximately 24% identity to a rat PP2C protein. Purified Ptc1 has Mg(2+)-dependent casein phosphatase activity, confirming that it is a PP2C enzyme. A ptc1 deletion mutant is viable and has approximately normal levels of PP2C activity, observations consistent with the fact that ptc1+ is a member of a multigene family. Although a ptc1 deletion mutant is viable, it has a greatly reduced ability to survive brief exposure to elevated temperature. Moreover, ptc1+ mRNA levels increase 5- to 10-fold during heat shock. These data, demonstrating that Ptc1 activity is important for survival of heat shock, provide one of the first genetic clues as to the biological functions of PP2C.

[The appearance and enlargement of localized pulmonary granuloma with eosinophilic infiltration during tuberculosis chemotherapy]

A pulmonary tumorous shadow appeared and enlarged in a 25 years-old male patient undergoing intensive chemotherapy for tuberculosis. The chest X-rays taken on admission revealed effused pleura in the right lung and nodular shadows in the upper area of the right lung. After 40 days of using isoniazid (INH), rifampicin (RFP) and streptomycin (SM), a homogeneous opacity, not previously observed, appeared in the middle area of the right lung (S5). Microscopic examination of the tissues obtained during a transbronchial lung biopsy disclosed epithelioid cell granulomas with marked eosinophilic infiltration. The presence of eosinophilic infiltration due to the admission of antituberculosis agents was disregarded because no change was observed in the new granulomatous shadows during the drug challenge tests and the lymphocyte stimulation test to INH, RFP and SM was negative. Transient aggravation during the initial phase of chemotherapy for pulmonary tuberculosis, such as in this case, is suspected cause by some eosinophilic allergic-induced mechanisms, against bacillary components.

Functional dissection of the phosphorylated termini of fission yeast DNA topoisomerase II

Fission Yeast DNA topoisomerase II (165 kD) consists of an enzymatically active 125-kD core, approximately 10-kD NH2-terminal and 30-kD COOH-terminal domains. The question addressed in the present study is what is the role of the topo II termini. Although deletion of either the NH2 or the COOH terminus is viable, deletion of both termini is lethal; the termini share an essential role for viability. We show here that topo II phosphorylation sites are localized in the terminal domains, but dephosphorylated topo II is still active. The topo II terminal sequences are required for nuclear localization; topo II double terminal deletion mutants are deficient for nuclear targeting, whereas wild-type and single deletion mutant topo IIs are transported into the nucleus with different efficiencies. Functional subdomains in the NH2 terminus are further dissected; we identified a 15 amino acid nuclear localization sequence (NLS) which is essential for viability and nuclear localization when the COOH terminus is deleted. This NLS could be substituted with SV-40 large T-antigen NLS. Two other functional subdomains were found; a non-essential acidic stretch which is phosphorylated and apparently enhances the nuclear localization and an essential hydrophilic stretch of unknown function. Motifs similar to these three NH2-terminal subdomains are also found in the COOH terminus. Our results support the possibility that phosphorylation of topo II does not play an essential role in fission yeast.

Effects of magnesium ion on the interaction of atrial muscarinic acetylcholine receptors and GTP-binding regulatory proteins

Muscarinic acetylcholine receptors (mAChR) purified from porcine atrium were reconstituted into lipid vesicles with GTP-binding regulatory proteins (G proteins, Gi, Go, or Gn) purified from porcine cerebrum. Apparent affinities of the reconstituted mAChR and G proteins for carbachol and GDP, respectively, were estimated from the effects of these ligands on the binding of [3H]-L-quinuclidinyl benzilate ([3H]QNB) to mAChR and [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTP gamma S) to G proteins in the presence of different concentrations of MgCl2. A total of 30-35% of reconstituted mAChRs exhibited low affinity for carbamylcholine, irrespective of the presence or absence of guanine nucleotides, and the remainder of the mAChRs showed high affinities for carbamylcholine in the absence of GTP or GDP and a low affinity in their presence. The affinity for carbamylcholine in the absence of guanine nucleotides, but not in their presence, increased with increases in MgCl2 concentration. Apparent Kd's for carbamylcholine were estimated to be approximately 100 microM in the presence of guanine nucleotides, 1.5 microM in the absence of guanine nucleotide and Mg2+ (< 0.1 microM), and 0.1 microM in the absence of guanine nucleotide and the presence of MgCl2 (10 mM). These results indicate that mAChRs may assume at least three different conformations that are characterized by different affinities for agonists. Furthermore, the data suggest that MgCl2 is not necessary for the formation of the mAChR-G protein complex, but can induce a conformational change in the complex. On the other hand, the presence of MgCl2 was necessary for carbamylcholine to influence the binding of guanine nucleotides.(ABSTRACT TRUNCATED AT 250 WORDS)

A functional 125-kDa core polypeptide of fission yeast DNA topoisomerase II

We purified fission yeast DNA topoisomerase II (topo II) to apparent homogeneity. It consists of a single 165-kDa polypeptide in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and, upon treatment with a bifunctional reagent, doubles its molecular weight. Limited proteolysis of intact topo II by papain produces a 125-kDa core, which lacks the N-terminal 75 and the C-terminal approximately 260 amino acids but still contains regions similar to those of bacterial or phage T4 topo II subunits. The core retains relaxing and unknotting activities. Further digestion inactivates the core, cleaving it at the middle of the GyrB-like domain and at the beginning of the GyrA-like domain. Therefore, papain appears to cleave spatially distinct subdomains of topo II. We made top2 mutant genes deleted of the C-terminal 286 or N-terminal 74 amino acids, which can substitute for the wild-type top2+ gene in mitosis and meiosis. However, a mutant containing deletions of both termini cannot rescue the top2 null mutant, despite the fact that the product is enzymatically active. Therefore, the top2 product of the doubly truncated gene may not fulfill all of the in vivo requirements for top2+ function.

Characteristics of the principal neutralizing determinant of HIV-1 prevalent in Japan

The principal neutralizing determinants (PNDs) of 29 human immunodeficiency virus type 1 (HIV-1) isolates in Japan were analyzed using polymerase chain reactions. The viruses were isolated from 16 hemophiliacs, 11 individuals infected by their sexual transmission and 1 patient infected by blood transfusion (total 28 patients). Two virus isolates which were obtained from the same individual at different periods were also analyzed. All individuals were Japanese except one. The results produced 32 different PND sequences. A highly conserved central core sequence (GPG) was present in 27 of 32 patients, similar to the number reported in the United States, despite the marked heterogeneity in flanking regions of PNDs. The PNDs of all the 16 HIV-1 isolates obtained from patients with coagulation disorders had GPG sequences. Secondary structure prediction of PNDs by a joint method suggested that they were composed of coil-beta strand-coil-beta strand-alpha helix. It is suggested that the conserved core sequence has a type I turn. These findings may be useful in planning further clinical trials for passive vaccination.

Identification of two novel GTP-binding protein alpha-subunits that lack apparent ADP-ribosylation sites for pertussis toxin

Molecular cloning of cDNAs encoding alpha-subunits of guanine nucleotide-binding regulatory proteins (G-proteins) has revealed the existence of nine species of alpha-subunits. We have identified two additional G-protein alpha-subunits, which we refer to as GL1 alpha and GL2 alpha, by isolating bovine liver cDNA clones that cross-hybridized at reduced stringency with bovine Gi1 alpha-subunit cDNA. The deduced amino acid sequences of GL1 alpha and GL2 alpha share 83% identity with each other and show 45-55% identity with those of other known G-protein alpha-subunits. Both GL1 alpha and GL2 alpha lack a consensus site for ADP-ribosylation by pertussis toxin. Messenger RNA corresponding to GL2 alpha was detected in all tissues examined, but GL1 alpha mRNA was detected only in liver, lung, and kidney. Antiserum prepared against a synthetic pentadecapeptide corresponding to the deduced carboxyl terminus of GL2 alpha specifically reacted with a 40-kDa protein in mouse liver, brain, lung, heart, kidney, and spleen. The amount of the 40-kDa protein was highest in brain and lung. We suggest that GL1 alpha and GL2 alpha are new members of a subfamily of pertussis toxin-insensitive G-proteins.