Phospholamban deficiency alters inactivation kinetics of L-type Ca2+ channels in mouse ventricular myocytes

Entry of Ca2+ through voltage-dependent L-type Ca2+ channels is critical for contraction in cardiac cells. In recent studies, cells from phospholamban (PLB) knockout (PLB-KO) mouse hearts showed significantly increased basal contractility with enhanced sarcoplasmic reticulum (SR) Ca2+ uptake. To test whether these effects of PLB ablation were associated with alterations of L-type Ca2+ channel function, we compared the properties of Ca2+ channel currents (I(Ca)) in ventricular myocytes isolated from wild-type (WT) and PLB-KO mouse hearts. L-type Ca2+ channels from mouse myocytes exhibited voltage-dependent gating and sensitivity to dihydropyridine drugs, similar to other mammalian species, and these properties were not altered by PLB ablation. I(Ca) from both WT and PLB-KO cells revealed two (fast and slow) components of inactivation kinetics. However, the proportion of the faster component was significantly larger in PLB-KO cells. Ryanodine (10 microM) reduced the rate of inactivation of I(Ca) for both WT and PLB-KO cells, but the reduction was more prominent in PLB-KO cells compared with WT cells. In contrast, the inactivation in a Ba2+ solution could be fitted by a single exponential similar to the slower component in Ca2+, and this was not altered in PLB-KO cells. The increase in the fast Ca2+-dependent inactivation component in PLB-KO cells supports the hypothesis that Ca2+ released from the SR regulates Ca2+ channel inactivation by affecting the levels of Ca2+ near the channel and suggests that this may be an important compensatory mechanism in the hyperdynamic PLB-KO heart.

Pharmacokinetics of antibiotics in neonates

The pharmacodynamics in neonates are different from those in adults and children because the absorption, distribution, metabolism and excretion of drugs in neonates are always changing for the following reasons. In neonates, the proportion of extracellular fluid is large; the amount of plasma protein is small; renal function is immature; and the hepatic enzyme system is immature. In addition, individual birthweights, gestational ages in weeks, cardiopulmonary functions and renal excretory functions vary. All of these factors should be considered when selecting the dose and administration method of a drug. In concrete terms the distribution volume is large, which causes a low maximum concentration. In addition neonate renal excretory function is low and the hepatic enzyme system is immature, thus the half-life of drugs is prolonged. Therefore, the same dose per unit time as that for children (including infants) needs to be administered to neonates at dosing intervals that may be prolonged according to renal function.

Magnetic resonance imaging of brain anomalies in fetal alcohol syndrome

OBJECTIVE

Postmortem studies of fetuses, infants, and young children with fetal alcohol syndrome (FAS) have demonstrated a variety of severe central nervous system (CNS) anomalies. We undertook this magnetic resonance study (1) to assess the spectrum of CNS anomalies that occur in a clinical sample of typical patients with FAS who are medically stable; and (2) to examine the relationship between CNS and facial anomalies.

METHODOLOGY

Magnetic resonance imaging was performed on a series of 10 patients (4 children, 3 adolescents, and 3 adults) who met criteria for FAS. We systematically evaluated each scan for brain anomalies and compared total brain tissue volume with that of healthy child, adolescent, and adult control subjects.

RESULTS

Six patients had some type of midline anomaly, ranging from partial to complete callosal agenesis (three patients) to hypoplastic corpus callosum (one patient), cavum septi pellucidi (three patients), and cavum vergae (two patients). These midline anomalies were associated with a greater number of facial anomalies. Other brain anomalies identified included micrencephaly, ventriculomegaly, and hypoplasia of the inferior olivary eminences.

CONCLUSION

Patients with classic FAS have a high incidence of midline brain anomalies. This finding is consistent with the concept that the midline CNS is a developmental field that is particularly susceptible to the teratogenic effects of alcohol. Furthermore, patients with more severe facial dysmorphologic characteristics are more likely to have midline brain anomalies. In addition, we observed a high incidence of micrencephaly with a wide range of severity.

Sensitive detection of human globin chains by microbore high-performance liquid chromatography and its forensic application

This paper describes a simple and sensitive high-performance liquid chromatographic (HPLC) method for the detection of human globin chains in blood and bloodstains. The method involves direct injection of the filtered samples of dilute hemolysates or bloodstain extracts onto a microbore C4 reversed-phase column (2.1 mm I.D.) with UV detection at 220 nm. Microbore HPLC offers a significant improvement in sensitivity with little loss of the resolution of globin chains and only small variations in the determination of gamma chain composition. The detection limit of hemoglobin (Hb) was 0.1 microgram, which is equivalent to about 1 nl of fresh whole blood. Umbilical cord blood could be differentiated from adult blood in stains that were up to twenty weeks old, by the presence of gamma globin chains. The present method will be useful for detection of abnormal Hbs and for the determination of gamma chain composition in clinical laboratories, as well as in the practice of forensic science for the analysis of minute amounts of blood and bloodstains.

Beneficial effects of amlodipine in a murine model of congestive heart failure induced by viral myocarditis. A possible mechanism through inhibition of nitric oxide production

BACKGROUND

Although calcium channel blockers have not been shown to be beneficial for the treatment of patients with heart failure, a recent clinical trial demonstrated a favorable effect of amlodipine on the survival of patients with heart failure resulting from nonischemic dilated cardiomyopathy. We investigated the effects of amlodipine on a murine model of congestive heart failure induced by the M variant of encephalomyocarditis virus (EMCV).

METHODS AND RESULTS

Four-week-old male DBA/2 mice were inoculated with EMCV and administered amlodipine, diltiazem, or vehicle PO for 2 weeks. The heart weight-to-body weight ratio and the histopathological grades of myocardial lesions were significantly lower and survival was significantly increased in the amlodipine-treated group (P < .01, P < .05, and P < .05, respectively) than in the control group. In vitro, amlodipine added to murine J774A.1 macrophages concomitant with EMCV inhibited nitrite formation in a concentration-dependent manner, but diltiazem did not. Furthermore, NG-monomethyl-L-arginine, an inhibitor of NO synthesis, decreased myocardial lesions significantly in this murine model. Immunohistochemistry revealed that the number of cells stained with antibody against an inducible NO synthase decreased significantly in the amlodipine-treated group compared with that in the control group (P < .01).

CONCLUSIONS

Amlodipine appears to have a protective effect against myocardial injury in this animal model of congestive heart failure. The therapeutic effect of amlodipine may be in part resulting from inhibition of overproduction of NO.

Ets-1 regulates angiogenesis by inducing the expression of urokinase-type plasminogen activator and matrix metalloproteinase-1 and the migration of vascular endothelial cells

The coordinate induction of protease activities and cell migration is a principal feature of endothelial cells (ECs) invading the interstitial space in the initial step of angiogenesis. However, the molecular mechanisms of these events are not fully characterized. Ets-1 is a member of the ets gene family of transcription factors, which binds to the Ets binding motif in the cis-acting elements and regulates the expression of certain genes. Four typical angiogenic growth factors, aFGF, bFGF, VEGF, and EGF, induced the expression of ets-1 mRNA in either human umbilical vein endothelial cells (HUVECs), ECV-304 cells (immortalized HUVECs), or human omental microvascular endothelial cells (HOMECs). The expression of ets-1 reached its maximum at 2 hr after factor addition and then decreased to the basal level by 12 hr. For characterization of the role of Ets-1 in angiogenesis, ets-1 antisense and sense oligodeoxynucleotides (ODNs) were constructed. The ets-1 antisense ODN but not sense ODN efficiently blocked the synthesis of Ets-1 protein by human ECs in response to angiogenic growth factors. Moreover, the ets-1 antisense ODN but not sense ODN almost completely abolished the binding of endothelial cell extract to DNA containing the Ets binding motif. The expression of urokinase-type plasminogen activator and matrix metalloproteinase-1 and the migration of ECs in response to growth factors were significantly inhibited by ets-1 antisense ODN but not by sense ODN. Tube formation by HOMECs in type 1 collagen gel stimulated with EGF was abrogated by ets-1 antisense ODN. Finally, the expression of Ets-1 protein in ECs during angiogenesis in vivo was confirmed by an immunohistochemical analysis using a murine angiogenesis model. These results indicate that the induction of ets-1 mRNA is a mutual phenomenon in ECs stimulated with angiogenic growth factors. Ets-1 appears to play an important role in angiogenesis, regulating the expression of proteases and the migration of ECs.

Bone mineral analysis in patients with biliary atresia after successful Kasai procedure

Metabolism is probably disturbed in patients with abnormal liver function who have undergone a successful Kasai procedure. We examined bone mineral metabolism in patients who have successfully undergone Kasai procedure. Bone mineral metabolism was examined in 8 patients with biliary atresia after a successful Kasai procedure. Five patients were female and 3 were male. The ages at Kasai procedure ranged from 50 to 80 days, and the follow-up periods ranged from 3 to 27 years after the operation. All patients eat a normal oral diet. We examined plasma levels of 25-OH-D3, 1, 25-(OH)2-D3, Ca and phosphorus (P). Bone mineral content of the lumbar spine (L2-L4) was assessed by dual energy x-ray absorptiometry (DEXA), and the data were expressed as a bone mineral density (BMD). Two patients showed abnormal levels on hepatic function tests. Plasma levels of 1, 25-(OH)2-D3, Ca, and P were normal in all patients. The level of 25-OH-D3 was normal in 7 patients. BMD levels were normal in 6 patients, but low in 2 who had undergone partial splenic embolization and splenectomy, respectively, due to hypersplenism. In long-term survivors of Kasai procedure, measurement of BMD may detect bone mineral deficiency earlier than measurements of serum levels of 25-OH-D, 1, 25-(OH)2-D, Ca and P.

Effect of mastication on regional cerebral blood flow in humans examined by positron-emission tomography with ¹⁵O-labelled water and magnetic resonance imaging

The interaction between mastication and cerebral blood flow was studied in 12 healthy volunteers (five males and seven females) aged 18-40 years. Positron-emission tomography (PET) autoradiography was carried out after bolus injection of 1.5 GBq H₂¹⁵O (¹⁵O-labelled water) with a half life of 2 min. The PET images were superimposed on magnetic resonance images of each participant. The regional cerebral blood flow images were normalized by the global cerebral blood flow value, and subtraction images (those during gum-chewing minus those during resting) were created and recut at the magnetic resonance image slice positions. Gum specially designed for chewing training was used. Mastication increased regional cerebral blood flow in the primary sensorimotor areas by 25-28%, in the supplementary motor areas and insulae by 9-17%, and in the cerebellum and striatum by 8-11%. These increases demonstrate that chewing activates widespread regions of the brain.

Voltammetric enzyme sensor for urea using mercaptohydroquinone-modified gold electrode as the base transducer

A voltammetric urea-sensing electrode was prepared by combining a lipid-attached urease layer with a 2,5-dihydroxythiophenol-modified gold electrode. A self-assembled monolayer of dihydroxythiophenol was prepared on the gold surface by soaking the electrode into an ethanolic solution containing the modifier. A layer of the lipid-attached enzyme and that of acetyl cellulose overcoat were successively made on the dihydroxythiophenol-modified electrode by applying a dip-coating procedure. The addition of urea in a test solution (10 mM phosphate buffer, pH 7.0) brought about an increase of pH near the urease layer. The pH shift accompanied a negative shift of the anodic peak, which corresponded to the electro-oxidation of dihydroxyphenol moiety to form quinone, on the linear sweep voltammograms for the urease/dihydroxythiophenol electrode. The concentration of urea (0.2-5 mM) could be determined by measuring the electrode current at -0.05 V versus Ag/AgCl from the voltammogram. The electrode was applied to the determination of urea in human urine; the measurement of electrode current at such a low potential provided the urea determination without any electrochemical interference from L-ascorbic acid and uric acid.

Interleukin-2 gene transduction into freshly isolated lung adenocarcinoma cells with adenoviral vectors

We evaluated the efficiency of gene transduction and of gene expression by adenoviral vectors in human lung adenocarcinoma cells. Freshly isolated cancer cells were collected from pleural effusions in adenocarcinoma patients by centrifugation with a Percoll gradient. Adenoviral vectors resulted in effective gene transduction into human lung cancer cell lines and into freshly isolated lung adenocarcinoma cells. In an experiment using the beta-galactosidase (LacZ) gene, the Adex1CA vector with a regulatory sequence of chicken beta-actin as promoter and an enhancer derived from cytomegalovirus produced a higher transduction ratio and greater expression levels than adenoviral vectors with other promoter systems. Transduction with Adex1CA vectors containing the human interleukin-2 (IL-2) gene (Adex1CAhIL-2) resulted in enhanced secretion of IL-2 from gene-modified lung cancer cells. Treatment with normal human serum inhibited gene transduction by Adex1CAhIL-2 but did not inhibit gene expression after transduction by Adex1CAhIL-2. The secretion of IL-2 from the gene-modified cells, which were irradiated at 100 Gy before transduction, continued for 8 days. In a mouse model, the intrapleural injection of IL-2 gene-modified 3LL cells transduced by Adex1CAhIL-2 could cure the pre-existing lung tumours with malignant pleural effusions to induce tumor-specific immunity. But these therapies did not show any therapeutic benefit on the pre-existing tumor in subcutaneous region. These data suggest a potentially useful but limited clinical role of Adex1CAhIL-2 in gene therapy for lung cancer patients.

[Localization of epileptogenic foci and visualization of propagating process in the seizure discharges using crosscorrelation analysis]

Electrocorticogram (ECoG) of intractable focal epilepsy was analyzed using AR model, wavelet analysis and crosscorrelation analysis. The sequential 3-dimensional visualization technique of phase shift maps was developed to localize the epileptic foci and to study their propagation process. The crosscorrelation of the epileptic discharges was calculated between the electrodes in every unit of time, to get the phase shift. More than two epileptogenic foci were localized and two kinds of propagating process were shown. These findings suggest that two kinds of mechanism might work in development of epileptic discharges, and our newly developed visualization technique is useful to investigate the epileptogenesis etiology.

Ductoplasty for an aberrant hepatic duct in a choledochal cyst

The confluence of the right and left hepatic ducts at the hepatic hilum frequently shows normal anatomic variations. Choledochal cysts (CC) are also accompanied by similar variations, and devices for free drainage of bile are occasionally required in biliary reconstruction. We present a CC that had an aberrant posterior branch of the right hepatic duct draining into the distal common hepatic duct. A capacious hepaticoduodenostomy at the hilum was performed after joining the hilar and aberrant ducts.

Changes of hepatic volume after successful Kasai operation

The number of long term survivors who have undergone Kasai operation for biliary atresia is increasing, but some have a hepatic dysfunction likely to require liver transplantation in the near future. Hepatic volume possibly reflects whole liver function, and our objective was to assess the changes of hepatic volume after Kasai operation. Ten patients were studied. Ages ranged from 3 to 27 years. They underwent Kasai operation at ages ranging from 50 to 80 days. Liver areas (cm2) on CT images were measured with an image processing and analysis program (NIH Image 1.57). Hepatic volume (cm3) was calculated by summing up the areas of each image and multiplying by slice thickness (cm). After Kasai operation, the size of the liver increased to 1.7-1.9 times the standard volume, and then reduced to normal size around 5 years of age. In the teens, hepatic volume decreased below the standard volume. Segmental hypertrophy accompanying atrophy of other hepatic segments was observed in 9 out of 10 patients; right lobe hypertrophy: 6, medial segment: 2, and lateral segment: 1. Therefore, progressive hepatic atrophy begins in the teens, but is compensated for by segmental hypertrophy.

Retinal detachment after branch retinal vein occlusion: influence of the type of break on the outcome of vitreous surgery

BACKGROUND

Branch retinal vein occlusion (BRVO) is occasionally complicated by two types of retinal breaks (retinal holes without vitreous traction or retinal traction tears) that may lead to a rhegmatogenous retinal detachment (RRD). The authors describe surgical results of vitrectomy for RRD after BRVO and investigate whether there is any difference between clinical features or surgical results from eyes with the two types of retinal breaks.

PATIENTS AND METHODS

The authors retrospectively studied 25 patients (25 eyes) who underwent vitrectomy for RRD after BRVO. Twelve of 25 eyes (48%) had a detachment secondary to one or more retinal holes (group I), and 13 of the eyes (52%) had one or more retinal tears (group II).

RESULTS

Seventeen of the eyes (68%) achieved total retinal reattachment after the initial surgery; 22 (88%) did so by the time of final examination. Patients with retinal holes achieved more favorable final vision than those with retinal tears (P = 0.0391). A higher rate of preoperative macular detachment (P = 0.0112) and a higher rate of recurrent retinal detachment after initial vitrectomy (P = 0.0302) were the factors associated with the reduced final visual acuity in patients with retinal tears. The increased rate of recurrent retinal detachment in patients with retinal tears was associated with a higher rate of existing preretinal neovascular membranes (P = 0.0112) and a trend toward an increased incidence of intraoperative iatrogenic retinal breaks.

CONCLUSION

Among patients who undergo vitrectomy for RRD after BRVO, better surgical results are expected in eyes with retinal holes without vitreous traction than in those with retinal traction tears. This difference is thought to be due to the difference in vitreoretinal anatomy between eyes with the two types of retinal breaks.

Traumatic brain injury in children and adolescents: psychiatric disorders in the first three months

OBJECTIVE

To assess predictive factors of psychiatric outcome in the first 3 months after traumatic brain injury (TBI) in children and adolescents.

METHOD

Subjects were children aged 6 to 14 years at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury psychiatric, behavioral, adaptive functioning, family functioning, and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales and neuroimaging was analyzed. The outcome measure was the development of a psychiatric disorder, never before present ("novel") in a subject during the first 3 months after the TBI.

RESULTS

Fifty subjects enrolled, and the analyses focused on 37 subjects followed up at 3 months. Increasing severity of injury, presence of a lifetime psychiatric disorder, family psychiatric history, family dysfunction, and lower socioeconomic class/preinjury intellectual function predicted the development of a "novel" psychiatric disorder in the first 3 months of follow-up.

CONCLUSIONS

These data suggest that there are children, identifiable through clinical assessment, at increased risk for development of psychiatric disorders in the first 3 months after TBI.

Correlation between mucosal inflammation and marginal bone loss around hydroxyapatite-coated implants: a 3-year cross-sectional study

In this study, a possible correlation between peri-implant mucosal inflammation and marginal bone loss in a group of patients who received two-stage hydroxyapatite-coated dental implants was evaluated 3 years after implantation. Thirty-two implants were evaluated as to their Plaque Index, Gingival Index, and crevicular fluid volume. Patients were divided into three groups: a control group with no inflammatory signs; a borderline group with moderate inflammation; and a gingivitis group with an established inflammatory process. Three dental radiographs per implant were analyzed at 2 months, 9 months, and 3 years after implantation by measuring bone height at the mesial and distal sides. Preliminary results indicated increased bone resorption in the gingivitis group compared with the control and borderline groups at both the mesial and distal surfaces (P < .05), suggesting correlation between mucosal inflammation and marginal resorption observed around these implants. Statistical analysis of correlation between the assessed mucosal parameters and bone loss indicated significance for Gingival Index and crevicular fluid volume (P < .05).

Morphologic and histochemical evaluation of muscle in patients with chronic pulmonary emphysema manifesting generalized emaciation

Twelve severely emaciated patients with emphysema and 4 control patients with mild emaciation were studied. Arterial blood gas analysis, pulmonary function tests, and muscle biopsy were performed. According to the percentage of ideal body weight (%IBW), patients were divided into two groups of 6 patients each; one with %IBW values greater than 70.0 (group 1) and the other with %IBW values less than 70.0 (group 2), and 4 control patients with emphysema whose %IBW values were greater than 85.5. %FEV1.0, PaO2 and Hugh-Jones scores in group 2 patients were consistent with significantly greater deterioration as compared with those in group 1 patients and controls. In the muscle fibers of 11 patients and 4 controls, nicotinamide and adenosine dinucleotide tetrazolium reductase activity was studded with spots. Nemalin rods were detected in 3 specimens in group 2 and in 1 specimen each in both group 1 and controls. These changes probably result from chronic hypoxemia. Fiber type grouping accompanied by type II dominant fiber atrophy was demonstrated in 5 patients of group 2, whereas type II fiber atrophy was shown in 2 specimens from patients of group 1. Diameters of both types I and II fibers in group 2 were smaller than those in group 1 and controls. Significant correlations were observed between fiber diameters and %IBW, %FEV1.0 and %IBW, and PaO2 and %IBW. Neurogenic and disuse muscular atrophy due to both hypoxic axonal disorder and disuse is likely to be the cause of the emaciation, and a 'vicious circle' between muscular atrophy, respiratory function and hypoxemia probably exists in group 2. Since mild or moderate emaciation was observed in controls and group 1 in spite of the lack of fiber atrophy, involvement of fat and connective tissue should also be taken into consideration to determine the cause of emaciation.

Increased growth and incidence of lymph node metastases due to the angiogenesis inhibitor AGM-1470

Using the rat tumour cell line LY80, a subline of Yoshida sarcoma, the effects of AGM-1470 on the growth of primary tumour and the incidence of regional lymph node metastasis were evaluated. AGM-1470 (30 mg kg(-1)) was administered subcutaneously or intravenously. Subcutaneous (s.c.) and intravenous (i.v.) injections were repeated for 8 days and 7 days respectively. Tumour growth of a primary region tended to be suppressed by AGM-1470. The s.c. tumours after sacrifice were much smaller in the AGM-1470-treated group (s.c. injection) than in the control groups. However, the growth of metastatic foci in the lymph nodes was prompted markedly by AGM-1470. All six of the AGM-1470-treated rats had developed swollen axillary lymph nodes and/or brachial lymph nodes on day 19 after tumour implantation (the 7th day after the last treatment) compared with one of six saline-injected rats and three of six vehicle-alone treated rats with swollen axillary lymph nodes. The weight of lymph nodes after sacrifice in the AGM-1470-treated rats was much heavier than that of the other two groups. Histological examination showed that in the AGM-1470-treated group, the cortex and the medulla of the axillary lymph nodes were almost entirely replaced by tumour cells while, in the vehicle alone group, a notable hyperplasia of the lymph nodes due to BT cell proliferation tended to be induced. In the saline group, although a slight hyperplasia of lymph nodes was observed, there were only a few lymph node metastases. In the case of i.v. injection of AGM-1470, similar results were obtained. It is thought that LY80 cells spread to regional lymph nodes at a comparatively early stage by some change or other in which AGM-1470 participated. From the present experiment, it is concluded that application of AGM-1470 alone to patients should be carried out with great caution.

Bone resorption inhibitors from hop extract

We searched hop extract for active component(s) that inhibited bone resorption in the pit formation assay, and isolated xanthohumol and humulone as active ingredients. Especially humulone had extraordinarily strong inhibitory activity and the IC50 (concentration of 50% inhibition) value was 5.9 x 10(-9)M.

Electrocardiographic nature of restored sinus rhythm after Cox maze procedure in patients with chronic atrial fibrillation who also had other cardiac surgery

OBJECTIVE

To characterise heart rate variability and high frequency components of restored sinus rhythm after the maze procedure. The maze procedure for chronic atrial fibrillation may prevent thrombotic events and improve the quality of life. However, the electrocardiographic nature of restored sinus rhythm after the maze procedure has not been fully elucidated.

PATIENTS AND METHODS

Between March 1993 and August 1995, 104 consecutive patients undergoing the maze procedure in combination with other cardiac surgery were studied. There were 100 long-term survivors (78 with mitral valve disease, 9 with aortic valve disease, 8 with congenital heart disease, and 5 others). Twenty age-matched patients with mitral valve disease who were in normal sinus rhythm preoperatively were enrolled as a control group. 30 days after surgery, the presence of arrhythmias and the circadian changes of heart rate variability were estimated by ambulatory electrocardiographic monitoring and the filtered P duration was evaluated by signal-averaged electrocardiogram.

RESULTS

Restoration of sinus rhythm was observed in 73 of 100 cases. Subjects were classified into three groups according to their postoperative ambulatory electro-cardiographic monitoring findings: patients in group 1 (n = 73) (1a: 58 regular sinus rhythm; 1b: 15 sinus rhythm with frequent premature atrial contractions (> 1000/day); patients in group 2 (n = 21) still had persistent atrial fibrillation; and patients in group 3 (n = 6) required permanent pacemaker implantation because of sick sinus syndrome. The success rate of restoration of sinus rhythm was 88.3% if left atrial diameter was small (< 65 mm). Circadian changes in the low frequency to high frequency power ratio in group 1a were significantly diminished compared with control group (P < 0.01). Furthermore, the filtered P duration in group 1a (150 (20) ms) and group 1b (158 (23) ms) were longer than in the control group (122 (11) ms) (P < 0.01).

CONCLUSIONS

The maze procedure may result in a decreased sinus response and non-uniform transmission of impulses in the atrium.

Characterization of a liver metastatic variant of murine colon 26 carcinoma cells

Intraportal vein injection of highly metastatic L5 cells consistently resulted in liver metastases (increases in the number of tumor colonies in the liver), whereas inoculation of P cells rarely did. L5 cells invaded the basement membrane Matrigel in greater numbers than did P cells, suggesting that the metastatic potential of L5 cells is partly related to enhanced invasive properties. The enhanced adhesion of L5 cells to fibronectin-, laminin- and Matrigel-coated substrates, as well as their haptotactic migration to fribronectin, may be associated with the preferential expression of VLA-2 and VLA-4 integrins on the surface of these cells detected by flow cytometry. Gelatin zymograms showed that the degradative activity of 72-kD gelatinases was greater in L5 cells than P cells. These results indicate that, in addition to adhesiveness and motility, the invasive ability of L5 cells may also be attributed to enhanced gelatinolytic activity. L5 cells grew more rapidly than P cells in vitro. Thus, an experimental model using highly metastatic colon 26 L5 cells would be useful for analyzing the molecular mechanism of liver metastasis and for evaluating the efficacy of treatment of occult micrometastases which may already have been disseminated at the time of surgery.

An in vitro study of high-strength resin posterior denture tooth wear

This in vitro study evaluated the wear resistance of a high-strength resin posterior denture tooth against eight opposing dental materials. The tooth specimen was cusp shaped and the opposing materials were formed as a 10 x 10 x 5 mm plate. All material combinations were tested using a machine designed to produce sliding contact 20 x 10(4) times at 60 cycles per minute and a 4-mm sliding distance per stroke in the buccolingual direction under a load of 1 kg. Wear analysis was measured as the total height loss of each material combination and the volume loss of each material. Wear against human enamel was evaluated as a control. The least loss was observed opposing a gold-silver-palladium-copper alloy, and the greatest loss was observed opposing porcelain. The volume loss of high-strength resin against gold-silver-palladium-copper alloy was as small as that against human enamel. High-strength resin wear was more significant against castable ceramics and porcelain. The volume losses of high-strength resin against high-strength resin, polycarbonate, or cobalt-chromium alloy were significantly larger than those against polyethersulfone, poly(methyl methacrylate), gold-silver-palladium-copper alloy, or human enamel. These findings suggest that the were resistance of high-strength resin is influenced considerably by opposing dental materials, and that the best combination was high-strength resin-gold-silver-palladium-copper alloy, and the poorest combination was high-strength resin-porcelain.