TMTC1 promotes invasiveness of ovarian cancer cells through integrins β1 and β4

Ovarian cancer is the most lethal gynecological malignancy and is characterized by peritoneal disseminated metastasis. Although O-mannosyltransferase TMTC1 is highly expressed by ovarian cancer, its pathophysiological role in ovarian cancer remains unclear. Here, immunohistochemistry showed that TMTC1 was overexpressed in ovarian cancer tissues compared with adjacent normal ovarian tissues, and high TMTC1 expression was associated with poor prognosis in patients with ovarian cancer. Silencing TMTC1 reduced ovarian cancer cell viability, migration, and invasion in vitro, as well as suppressed peritoneal tumor growth and metastasis in vivo. Moreover, TMTC1 knockdown reduced cell-laminin adhesion, which was associated with the decreased phosphorylation of FAK at pY397. Conversely, TMTC1 overexpression promoted these malignant properties in ovarian cancer cells. Glycoproteomic analysis and Concanavalin A (ConA) pull-down assays showed that integrins β1 and β4 were novel O-mannosylated protein substrates of TMTC1. Furthermore, TMTC1-mediated cell migration and invasion were significantly reversed by siRNA-mediated knockdown of integrin β1 or β4. Collectively, these results suggest that TMTC1-mediated invasive behaviors are primarily through integrins β1 and β4 and that TMTC1 is a potential therapeutic target for ovarian cancer.

A new laboratory surrogate (Monocyte Chemotactic Protein-1) for Disease Activity Score28: a favourable indicator for remission in rheumatoid arthritis

This prospective one-year follow-up study was conducted from 835 visits in 178 rheumatoid arthritis (RA) patients. Tender-/swollen-joint count, Health Assessment Questionnaire Disability Index (HAQ-DI), Disease Activity Score 28-ESR (DAS28-ESR), DAS28-CRP, Simplified Disease Activity Index (SDAI) and DAS28-monocyte chemotactic protein-1 (DAS28-MCP-1) scores were obtained every 3 months. Radiographs of hands and feet were acquired at baseline and one year. We evaluated the correlation and accuracy of activity scores in predicting remission, HAQ-DI changes and radiographic changes. DAS28-MCP-1 correlated strongly with DAS28-ESR, DAS28-CRP and SDAI scores (0.830, 0.899 and 0.931, respectively, with all P < 0.001). Score changes of DAS28-MCP-1 were comparable to those of DAS28-ESR, DAS28-CRP and SDAI in predicting changes in HAQ-DI and bone erosion. DAS28-MCP-1 (<2.2) was better than DAS28-ESR (<2.6) in indicating modified American Rheumatism Association remission and 2011 American College of Rheumatology/European League Against Rheumatism remission (75.61% vs. 36.99% and 81.71% vs. 49.13%, respectively) with odds ratios of 5.28 and 4.62 (both P < 0.001), respectively. We compared DAS28-MCP-1 with SDAI (≦3.3) in indicating remission with odds ratios of 2.63 (P = 0.002) and 0.98, respectively (and DAS28-MCP-1 with DAS28-CRP < 2.5: 1.33 and 0.92). Therefore, DAS28-MCP-1 is useful as an alternative in assessing RA activity.

Prevention of Postdental Procedure Bacteremia: A Network Meta-analysis

Postdental procedure bacteremia is common and troublesome. The comparative efficacy of multiple prophylactic interventions is unclear. We compared the efficacy of interventions for the prevention of postdental procedure bacteremia. We conducted a review of ClinicalKey, Cochrane CENTRAL, Embase, ProQuest, PubMed, ScienceDirect, Web of Science, and ClinicalTrials.gov from inception to December 4, 2018. Randomized controlled trials that evaluated prophylactic interventions for the prevention of postdental procedure bacteremia were eligible. The primary outcome was the incidence of postdental procedure bacteremia. A total of 24 trials were included with 2,147 participants. Our network meta-analysis demonstrated that intravenous administration of 1,000/200 mg of amoxicillin/clavulanate provided the least incidence of postdental procedure bacteremia among all the prophylactic interventions (odds ratio = 0.03, 95% CI = 0.00 to 0.63) as compared with the placebo/controls. Oral 3 g of amoxicillin had the least incidence of postdental procedure bacteremia among all oral or topical forms of prophylactic interventions (odds ratio = 0.10, 95% CI = 0.02 to 0.44) as compared with the placebo/controls. No serious adverse events, such as anaphylactic shock, mortality, and the development of antibiotic-resistant bacteria, were reported. None of the included subjects were of high risk of infectious endocarditis. Our network meta-analysis demonstrates that intravenous amoxicillin/clavulanate and oral amoxicillin might be the best prophylactic interventions in preventing postdental procedure bacteremia among all the oral/topical forms of interventions for the overall populations.

miR-151-3p Targets TWIST1 to Repress Migration of Human Breast Cancer Cells

TWIST1 is a highly conserved basic helix-loop-helix transcription factor that contributes to cancer metastasis by promoting an epithelial-mesenchymal transition and repressing E-cadherin gene expression in breast cancer. In this study, we explored the potential role of miR-151 in TWIST1 expression and cancer properties in human breast cancer cells. We found that the human TWIST1 3’UTR contains a potential binging site for miR-151-3p at the putative target sequence 5’-CAGUCUAG-3’. Using a TWIST1-3’UTR luciferase reporter assay, we demonstrated that the target sequence within the TWIST1 3’UTR is required for miR-151-3p regulation of TWIST1 expression. Moreover, we found that ectopic expression of miR-151-3p by infection with adenoviruses expressing miR-151 significantly decreased TWIST1 expression, migration and invasion, but did not affect cell growth and tumorsphere formation of human breast cancer cells. In addition, overexpression of the protein coding region without the 3’UTR of TWIST1 reversed the repression of cell migration by miR-151-3p. Furthermore, knockdown of miR-151-3p increased TWIST1 expression, reduced E-cadherin expression, and enhanced cell migration. In conclusion, these results suggest that miR-151-3p directly regulates TWIST1 expression by targeting the TWIST1 3’UTR and thus repressing the migration and invasion of human breast cancer cells by enhancing E-cadherin expression. Our findings add to accumulating evidence that microRNAs are involved in breast cancer progression by modulating TWIST1 expression.

MEG localization of rolandic spikes with respect to SI and SII cortices in benign rolandic epilepsy

The purpose of this study was to study the relationship between interictal spike sources and somatosensory cortices in benign rolandic epilepsy of childhood (BREC) using a whole-scalp neuromagnetometer. We recorded spontaneous magnetoencephalography (MEG) and EEG signals and cortical somatosensory-evoked magnetic fields (SEFs) to electric stimulation of the median nerve in 9 children with BREC. Interictal rolandic discharges (RDs) and SEFs were analyzed by equivalent current dipole (ECD) modeling. Based on the orientation and locations of corresponding ECDs, we compared generators of RDs with primary (SI) and second somatosensory cortices (SII). Our results showed that RDs and SII responses had similar ECD orientation on the magnetic field maps. The ECDs of RDs were localized 15.3 +/- 1.9 and 12.2 +/- 2.8 mm anterior to SI and SII, respectively. The spatial distance on average from the location of RDs to SII (21.9 +/- 1.6 mm) cortex was significantly shorter than to SI cortex (29.7 +/- 1.7 mm) (P<0.01, Wilcoxon signed-rank test). In conclusion, the cortical generators for RDs in patients with BREC are localized in the precentral motor cortex, closer to hand SII than to SI cortex.

Magnetoencephalographic yield of interictal spikes in temporal lobe epilepsy. Comparison with scalp EEG recordings

To compare magnetoencephalography (MEG) with scalp electroencephalography (EEG) in the detection of interictal spikes in temporal lobe epilepsy (TLE), we simultaneously recorded MEG and scalp EEG with a whole-scalp neuromagnetometer in 46 TLE patients. We visually searched interictal spikes on MEG and EEG channels and classified them into three types according to their presentation on MEG alone (M-spikes), EEG alone (E-spikes), or concomitantly on both modalities (M/E-spikes). The M-spikes and M/E-spikes were localized with MEG equivalent current dipole modeling. We analyzed the relative contribution of MEG and EEG in the overall yield of spike detection and also compared M-spikes with M/E-spikes in terms of dipole locations and strengths. During the 30- to 40-min MEG recordings, interictal spikes were obtained in 36 (78.3%) of the 46 patients. Among the 36 patients, most spikes were M/E-spikes (68.3%), some were M-spikes (22.1%), and some were E-spikes (9.7%). In comparison with EEG, MEG gave better spike yield in patients with lateral TLE. Sources of M/E- and M-spikes were situated in the same anatomical regions, whereas the average dipole strength was larger for M/E- than M-spikes. In conclusion, some interictal spikes appeared selectively on either MEG or EEG channels in TLE patients although more spikes were simultaneously identified on both modalities. Thus, simultaneous MEG and EEG recordings help to enhance spike detection. Identification of M-spikes would offer important localization of irritative foci, especially in patients with lateral TLE.

A left-lateralized network for reading Chinese words: a 3 T fMRI study

fMRI was used to investigate brain organization for reading in Chinese. Subjects were shown two-character Chinese words. A control task was used to eliminate the non-linguistic visual and motor confounds. Results show that naming of Chinese logographs is characterized by left-lateralized neuronal networks for the processing of orthographic, phonological, and semantic attributes. The orchestration of the middle frontal cortex, superior temporal cortex, superior parietal cortex, basal temporal area and extrastriate cortices of the left hemisphere may manifest the particularity of the central representation of simple word naming in Chinese.

Current status of human parasitic infections in Taiwan

The eradication of the 2 mosquito-borne parasitic diseases, malaria and lymphatic filariasis, is one of the greatest achievements of the parasite control campaigns in Taiwan. Most of the soil-transmitted nematode infections, with the exception of pinworm infection, are currently well controlled and limited to some aboriginal areas. Food-borne parasitic zoonosis such as infections with Angiostrongylus cantonensis, Clonorchis sinensis, and Taenia saginata asiatica are not rare, but the former is seasonal and the latter 2 are ethnically and geographically associated. Intestinal protozoal infections with Giardia lamblia and Cryptosporidium parvum are at low levels but may be widely distributed. Opportunistic protozoal infections among patients with acquired immunodeficiency syndrome, which included amebic colitis, Pneumocystis carinii pneumonia, and cerebral toxoplasmosis, are becoming increasingly important. The rapid increase in international travel and the introduction of large numbers of foreign workers from other countries in Southeast Asia may change the epidemiological patterns of parasitic infections in Taiwan.

Activation of the hypothalamus characterizes the acupuncture stimulation at the analgesic point in human: a positron emission tomography study

We performed a positron emission tomography study, using regional cerebral blood flow as the index of brain activity, to address the specificity of brain activation pattern by acupuncture stimulation of short duration at the classical analgesic point. Needling manipulation at 2 Hz was performed at a classical point of prominent analgesic efficacy (Li 4, Heku) and a near-by non-classical/non-analgesic point, respectively, in normal subjects. Regions activated by acupuncture stimulation at Li 4 included the hypothalamus with an extension to midbrain, the insula, the anterior cingulate cortex, and the cerebellum. Of note, it was only the stimulation at Li 4 that activated the hypothalamus under the similar psychophysical ratings of acupuncture sensation (deqi) as elicited by the stimulation at the two points, respectively. The data suggested that the hypothalamus might characterize the central expression of acupuncture stimulation at the classical analgesic point and serve as one key element in mediating analgesic efficacy of acupuncture stimulation.

Electroacupuncture-induced neural activation detected by use of manganese-enhanced functional magnetic resonance imaging in rabbits

OBJECTIVE

To investigate the effects of acupuncture on neural activity detected by use of manganese-enhanced functional magnetic resonance imaging (fMRI) and elucidate the relationship between somatic acupoint stimulation and brain activation.

ANIMALS

40 New Zealand White rabbits.

PROCEDURE

Manganese-enhanced fMRI was performed in anesthetized rabbits manipulated with electroacupuncture (EA) on Zusanli (ST-36) and Yanglingquan (GB-34) acupoints. Image acquisition was performed on a 1.5T superconductive clinical scanner with a circular polarized extremity coil. T1-weighted images were acquired sequentially as follows: baseline, after mannitol injection, after manganese infusion, and 5 and 20 minutes after initiation of EA.

RESULTS

Changes in focal neural activity were detected by use of manganese-enhanced fMRI. Stimulation on Zusanli (ST-36) for 5 minutes resulted in activation of the hippocampus, whereas stimulation on Yanglingquan (GB-34) resulted in activation of the hypothalamus, insula, and motor cortex. Activation became less specific after 20 minutes of EA. Furthermore, stimulation on ipsilateral acupoints led to bilateral brain activation.

CONCLUSIONS AND CLINICAL RELEVANCE

Each acupoint has a corresponding cerebral linkage, and stimulation on these points resulted in time-dependent neural activation. Understanding the linkage between peripheral acupoint stimulation and central neural pathways may provide a useful guide for clinical applications of acupuncture.

MR perfusion studies of brain for patients with unilateral carotid stenosis or occlusion: evaluation of maps of "time to peak" and "percentage of baseline at peak"

Maps of "time to peak" (TTP) and "percentage of baseline at peak" (PBP) were compared with maps of conventional brain perfusion parameters, namely, mean transit time (MTT) and relative cerebral blood volume (rCBV). We performed MR perfusion studies in 11 patients. All of them had occlusion or high-grade stenosis of the unilateral carotid artery. Three areas of old infarct, 4 areas of new infarct, and 10 areas of brain without infarct were evaluated specifically. In all these cases, the TTP maps appeared similar to the MTT maps. They showed increases, normal values, or decreases at the same time in all areas evaluated. Most areas of abnormally decreased CBV had increased signal in PBP maps. In conclusion, the TTP map provided the same qualitative information as MTT. PBP seemed correlated inversely to CBV and was less sensitive in demonstrating abnormality.

A dual role for the kinase-like domain of the tyrosine kinase Tyk2 in interferon-alpha signaling

Tyrosine kinases of the Janus kinase family initiate cellular responses through their association with receptors for alpha-helical cytokines. In addition to a tyrosine kinase domain, these enzymes possess a kinase-like (KL) domain, whose function remains elusive. To investigate the role of the KL domain of Tyk2 in interferon-alpha/beta signaling, we transfected a library of Tyk2 cDNAs containing random point mutations in KL into Tyk2-negative cells and selected for loss-of-function Tyk2 mutants. Four such mutants, V584D, G596V, H669P, and R856G, were identified through this screen. Like the wild-type Tyk2, the mutant proteins were able to sustain the level of IFNAR1 receptor protein. However, all four mutants were incapable of restoring high-affinity interferon-alpha binding in Tyk2-negative cells and were also catalytically impaired, even when transiently overexpressed. Interferon-alpha induced phosphorylation, and gene expression could be detected in V584D- or G596V-expressing cells, but not in H669P- or R856G-expressing cells. Furthermore, H669P and R856G proteins were constitutively highly phosphorylated. All together, our findings demonstrate that an intact KL domain is essential for the intrinsic catalytic activity of Tyk2 and for the establishment of a high-affinity interferon-alpha receptor complex.

The Janus kinase family of protein tyrosine kinases and their role in signaling

In the early 1990s, the search for protein kinases led to the discovery of a novel family of non-receptor tyrosine kinases, the Janus kinases or JAKs. These proteins were unusual because they contained two kinase homology domains and no other known signaling modules. It soon became clear that these were not 'just another' type of kinase. Their ability to complement mutant cells insensitive to interferons and to be activated by a variety of cytokines demonstrated their central signaling function. Now, as we approach the end of the decade, it is evident from biochemical studies to knockout mice that JAKs play non-redundant functions in development, differentiation, and host defense mechanisms. Here, recent progress is reviewed, with particular emphasis on structure-function studies aimed at revealing how this family of tyrosine kinases is regulated.

Disruption of a putative SH3 domain and the proline-rich motifs in the 53-kDa substrate of the insulin receptor kinase does not alter its subcellular localization or ability to serve as a substrate

The recently identified 53-kDa substrate of the insulin receptor family was further characterized in several retroviral-generated stable cell lines overexpressing the wild type and various mutant forms of the protein. To facilitate the study of its subcellular localization in NIH3T3 cells overexpressing insulin receptor, a myc epitope-tag was added to the carboxy terminus of the 53-kDa protein. Like the endogenous protein in Chinese hamster ovary cells, the expressed myc-tagged 53-kDa protein was found partially in the particulate fraction and was tyrosine phosphorylated in insulin-stimulated cells. Immunofluorescence studies showed for the first time that a fraction of the 53-kDa protein was localized to the plasma membrane. Confocal microscopy of cells double-labeled with antibodies to the insulin receptor and the myc epitope showed the two proteins co-localize at the plasma membrane at the level of light microscopy. Further analyses of the protein sequence of the 53-kDa substrate revealed the presence of a putative SH3 domain and two proline-rich regions, putative binding sites for SH3 and WW domains. Disruption of these three motifs by the introduction of previously characterized point mutations did not affect the membrane localization of the 53-kDa protein, its ability to serve as substrate of the insulin receptor, or its colocalization with the insulin receptor, suggesting these domains are not important in the subcellular targeting of the protein and instead may function in the interaction with subsequent signaling proteins.

Characterization and cloning of a 58/53-kDa substrate of the insulin receptor tyrosine kinase

A monoclonal antibody has been produced which immunoprecipitates 58- and 53-kDa proteins which are rapidly tyrosine phosphorylated in insulin-treated cells. These proteins can also be tyrosine phosphorylated in vitro by the isolated human insulin receptor. Increased tyrosine phosphorylation of these proteins is also observed in cells expressing a transforming chicken c-Src (mutant Phe-527) and in cells with the activated tyrosine kinase domains of the Drosophila insulin receptor, human insulin-like growth factor I receptor, and human insulin receptor-related receptor. P58/53 did not appear to associate with either the GTPase activating protein of Ras (called GAP) or the phosphatidylinositol 3-kinase by either co-immunoprecipitation experiments or in Far Westerns with the SH2 domains of these two proteins. Since p58/53 did not appear, by immunoblotting, to be related to any previously described tyrosine kinase substrate such as the SH2 containing proteins SHC and the tyrosine phosphatase Syp, the protein was purified in sufficient amounts to obtain peptide sequence. This sequence was utilized to isolate a cDNA clone that encodes a previously uncharacterized 53-kDa protein which, when expressed in mammalian cells, is tyrosine phosphorylated by the insulin receptor.

Electromechanical effects of caffeine in failing human ventricular myocardium

We studied, using standard microelectrode technique, the effects of caffeine alone and in conjunction with epinephrine in ventricular myocardial fibers obtained from the failing hearts of 12 recipients of heart transplant. Results revealed that caffeine (1-3 mM) prolonged slightly the duration of fast response action potential near final repolarization and the twitch curve but slightly increased, or even decreased, the twitch force. Epinephrine (3 microM) induced a submaximal positive inotropic effect in myocardial fibers obtained from the failing hearts. Caffeine at 1 mM significantly potentiated the force of contraction and accelerated the rate of twitch relaxation increased by epinephrine. Increasing concentration of caffeine to 3 mM in the presence of epinephrine did not enhance further the twitch force but rather induced the delayed after-depolarization in two of eight experiments. In a preparation from one patient with dilated cardiomyopathy, the combination of caffeine and epinephrine induced repetitive triggered rhythms. The present findings suggest that, in human ventricular myocardium obtained from certain patients transplanted for congestive heart failure, caffeine could induce positive inotropy and triggered automaticity through a potentiation of the actions of catecholamines.

Modeling of natural organic matter transport processes in groundwater

A forced-gradient tracer test was conducted at the Georgetown site to study the transport of natural organic matter (NOM) in groundwater. In particular, the goal of this experiment was to investigate the interactions between NOM and the aquifer matrix. A detailed three-dimensional characterization of the hydrologic conductivity heterogeneity of the site was obtained using slug tests. The transport of a conservative tracer (chloride) was successfully reproduced using these conductivity data. Despite the good simulation of the flow field, NOM breakthrough curves could not be reproduced using a two-site sorption model with spatially constant parameters. Preliminary results suggest that different mechanisms for the adsorption/desorption processes, as well as their spatial variability, may significantly affect the transport and fate of NOM.

In vivo dynamic MRI tracking of rat T-cells labeled with superparamagnetic iron-oxide particles

Dynamic MRI tracking of rat T-cells in vivo is performed in rat testicles after labeling isolated rat T-cells in vitro with superparamagnetic dextran-coated iron-oxide particles, BMS180549. Tissue inflammation induced by the local injection of the calcium ionophore, A23187, is used to attract labeled T-cells. Gradient-echo MR images of rat testicles show a statistically significant decrease (4%) of the signal intensity in areas of injection of A23187 as early as 30 min after intravenous infusion of 2 x 10(8) labeled T-cells. The signal change reaches its maximum (6-7% decrease) at about 60-120 min after cell infusion. T2-mapping also shows a decrease of T2 in the areas with A23187. Image quantitation, which includes a chemical-shift effect, significantly enhances the sensitivity for detection of superparamagnetically labeled T-cells. Localization of labeled T-cells in rat testicles has been verified by fluorescence microscopy studies of T-cells co-labeled with a lipophilic fluorescent carbocyanine dye, 1,1-dioctadecyl-3,3,3',3'-tetramethyl-lindocarbocyanine perchlorate. These results represent the first successful demonstration of dynamic tracking of specific cells in vivo using MRI.

Insulin receptor signaling in Madin-Darby canine kidney cells overexpressing the human insulin receptor

We have developed and characterized a line of Madin-Darby canine kidney (MDCK) cells overexpressing the human insulin receptor. The expressed receptor was found to be processed normally, and its intrinsic tyrosine kinase was determined to be functional from both in vitro and in vivo phosphorylation studies. The expressed receptor was able to mediate an insulin-stimulated increase in both anti-phosphotyrosine-precipitable and anti-insulin receptor substrate 1-precipitable phosphatidylinositol 3-kinase activity. Moreover, insulin-induced glycogen synthase activity was greater and more sensitive to insulin in the transfected cells than in the parental cells. Interestingly, insulin promoted tubule-like growth in cells overexpressing the insulin receptor but not in the parental cells. Another advantage of this cell system lies in its ability to polarize into distinct basolateral and apical membrane compartments. With the use of biotinylation and Western analysis, the expressed insulin receptor was found to be preferentially expressed in the basolateral membrane (fivefold greater) in comparison with the apical membrane. Therefore, MDCK cells overexpressing the insulin receptor represent a novel system to study not only the pathway of insulin signaling, but also this pathway in the context of cell polarity.

Intracellular labeling of T-cells with superparamagnetic contrast agents

Isolated rat T-cells have been labeled intracellularly, using endocytosis uptake of two superparamagnetic contrast agents, AquaMag100 and BMS180549, which are both iron-oxide particles coated with dextran. No deterioration of cell proliferation response to mitogen stimulation was observed after labeling with either superparamagnetic contrast agent. AquaMag100 particles show aggregation and co-precipitation in culture media for T-cells. BMS180549 particles not only produce no observable aggregation or co-precipitation, but also have a higher efficiency for labeling T-cells than AquaMag100. The efficiency of cell labeling was determined by measuring the decrease in the spin-spin relaxation time of the water proton in cell samples containing 1 x 10(7) labeled T-cells/milliliter of 2% w/w gelatin. After optimization of the labeling procedures, a shortening of the spin-spin relaxation time by a factor of approximately 7 to 10 has been demonstrated. Under the present experimental conditions, the up-regulation of low density lipoprotein receptor does not increase the labeling efficiency by endocytosis. Our results suggest that intracellular labeling of specific cell types can be achieved with good efficiency and the labeled cells can be detected by magnetic resonance imaging in rat testicles in vivo.

Evolution of rodent lysozymes: isolation and sequence of the rat lysozyme genes

Mice have two lysozyme c genes that are the products of a gene duplication. The rat genome also possesses two lysozyme genes, which implies that the duplication of the lysozyme gene preceded the mouse-rat divergence. Concerted evolution has homogenized the 3' half (middle of exon 2 through 3' flanking) of the genes in each species. A mosaic pattern of concerted evolution is found for the 5' half of the gene, with both the 5' and 3' ends, but not the middle, of exon 1 evolving in a concerted fashion. Differences exist in the homogenization pattern in the rat and mouse, suggesting the existence of species-specific patterns of concerted evolution. Exon 1 contains most of the amino acid substitutions that distinguish mouse M from mouse P lysozyme or rat 1 from rat 2 lysozyme. Some of the amino acid differences found between mouse lysozyme genes are found also in the rat, and they suggest that rat 1 and 2 are homologous to mouse M and P, respectively. Nuclease S1 mapping indicated that only the rat 1 gene is expressed at detectable levels, and, specifically, that this gene is expressed by cells in the lung, small intestine, and spleen. The mouse expresses different lysozyme genes in the intestinal (P) and macrophage (M) cells, while the rat expresses only one gene in both of these tissues. The absence of detectable expression and the accumulation of a large number of amino acid substitutions in the parts of exons 1 and 2 of the rat 2 gene not participating in concerted evolution suggest that the rat 2 gene is a pseudogene.

Arrhythmogenic mechanisms in human atrial and ventricular muscle fibers

Mechanisms which may lead to cardiac arrhythmias were studied in atrial and ventricular tissues from human hearts. In human atrial fibers, diastolic depolarization (DD) was consistently present, but did not induce spontaneous discharge. Epinephrine enhanced DD, could induce delayed afterdepolarizations (DADs) and (in combination with strophanthidin) trigger repetitive activity. The presence of DD modified the recovery of premature action potentials. Human ventricular fibers did not exhibit DD and were more resistant to Ca overload. It is concluded that in atrial tissues the presence of DD may not induce automatic arrhythmias, but it may influence conduction and re-entry rhythms. Cardioactive drugs may induce DADs and repetitive activity in the atria and less easily in the ventricles. The attainment of a threshold may be facilitated when DADs are superimposed.

[Etiologies of unilateral block of epidural anesthesia: a case report]

We would like to present a patient, who was a 60 years old man, 160 cm tall, weighing 55 kg, which received debridement for his pressure sores under epidural anesthesia. While inserting the Touhy needle, there was obvious loss of resistance at the level of 9 cm below the skin. When the test dose was injected, the compliance was good. Later, the anesthesia behaved as unilateral block. After the operation, the computerized tomography revealed the epidural catheter was between the facia of right psoas major muscle. Form this case, there were some lesions: (1) The distance from the skin to the lumbar dura mater is seldom longer than 7 cm. (2) The obvious loss-of-resistance and good compliance of test dose are not the guarantee of epidural anesthesia. (3) The psoas block may be another cause of unilateral block of lumbar epidural anesthesia.