High-Fat Diet Induces Disruption of the Tight Junction-Mediated Paracellular Barrier in the Proximal Small Intestine Before the Onset of Type 2 Diabetes and Endotoxemia.

BACKGROUND/AIM: A link between an impaired intestinal barrier, endotoxemia, and the pathogenesis of metabolic diseases, such as type 2 diabetes mellitus (T2DM), has been proposed. In previous work, we have demonstrated that the tight junction (TJ)-mediated intestinal barrier in ileum/colon was marginally changed in prediabetic mice; therefore, it does not seem to mainly contribute to the T2DM onset. In this study, the TJ-mediated epithelial barrier in the duodenum and jejunum was evaluated in mice during the development of type 2 prediabetes. METHODS/RESULTS: HF diet induced prediabetes after 60 days associated with a significant rise in intestinal permeability to the small-sized marker Lucifer yellow in these mice, with no histological signs of mucosal inflammation or rupture of the proximal intestine epithelium. As revealed by immunofluorescence, TJ proteins, such as claudins-1, -2, -3, and ZO-1, showed a significant decrease in junctional content in duodenum and jejunum epithelia, already after 15 days of treatment, suggesting a rearrangement of the TJ structure. However, no significant change in total cell content of these proteins was observed in intestinal epithelium homogenates, as assessed by immunoblotting. Despite the changes in intestinal permeability and TJ structure, the prediabetic mice showed similar LPS, zonulin, and TNF-α levels in plasma or adipose tissue, and in intestinal segments as compared to the controls. CONCLUSION: Disruption of the TJ-mediated paracellular barrier in the duodenum and jejunum is an early event in prediabetes development, which occurs in the absence of detectable endotoxemia/inflammation and may contribute to the HF diet-induced increase in intestinal permeability.

Evaluation of Memantine in AAV-AD Rat: A Model of Late-Onset Alzheimer's Disease Predementia.

BACKGROUND: Though our understanding of Alzheimer's disease (AD) remains elusive, it is well known that the disease starts long before the first signs of dementia. This is supported by the large number of symptomatic drug failures in clinical trials and the increased trend to enroll patients at predementia stages with either mild or no cognitive symptoms. However, the design of pre-clinical studies does not follow this attitude, in particular regarding the choice of animal models, often irrelevant to mimic predementia Late Onset Alzheimer's Disease (LOAD). OBJECTIVES: We aimed to pharmacologically validate the AAV-AD rat model to evaluate preventive treatment of AD. METHODS: We evaluated an N-methyl-D-aspartate receptor antagonist, named memantine, in AAV-AD rats, an age-dependent amyloid rat model which closely mimics Alzheimer's pathology including asymptomatic and prodromal stages. Memantine was used at a clinically relevant dose (20 mg daily oral administration) from 4 (asymptomatic phase) to 10 (mild cognitive impairment phase) months of age. RESULTS: A 6-month treatment with memantine promoted a non-amyloidogenic cleavage of APP followed by a decrease in soluble Aß42. Consequently, both long-term potentiation and cognitive impairments were prevented. By contrast, the levels of hyperphosphorylated endogenous tau remained unchanged, indicating that a long-term memantine treatment is ineffective to restrain the APP processing-induced tauopathy. CONCLUSIONS: Together, our data confirm that relevant models to LOAD, such as the AAV-AD rat, can provide a framework for a better understanding of the disease and accurate assessment of preventive treatments.

Repression of origin assembly in metaphase depends on inhibition of RLF-B/Cdt1 by geminin.

Eukaryotic replication origins are 'licensed' for replication early in the cell cycle by loading Mcm(2-7) proteins. As chromatin replicates, Mcm(2-7) are removed, thus preventing the origin from firing again. Here we report the purification of the RLF-B component of the licensing system and show that it corresponds to Cdt1. RLF-B/Cdt1 was inhibited by geminin, a protein that is degraded during late mitosis. Immunodepletion of geminin from metaphase extracts allowed them to assemble licensed replication origins. Inhibition of CDKs in metaphase stimulated origin assembly only after the depletion of geminin. These experiments suggest that geminin-mediated inhibition of RLF-B/Cdt1 is essential for repressing origin assembly late in the cell cycle of higher eukaryotes.

Disrupting actin filaments promotes efficient transfection of a leukemia cell line using cell adhesive protein-embedded carbonate apatite particles.

Tumor cells such as leukemia and lymphoma cells are obvious and attractive targets for gene therapy. Gene transfer and expression for cytokine and immunomodulatory molecules in various kinds of tumor cells have been shown to mediate tumor regression and antimetastatic effects. Moreover, genetically modified leukemia cells expressing costimulatory molecules or cytokines are likely to have significant therapeutic roles for patients with leukemia. One of the major hurdles to the successful implementation of these promising approaches is the lack of a suitable nanocarrier for transgene delivery and expression in a safe and effective manner. Recently, we reported on the development of a safe, efficient nanocarrier system of carbonate apatite that can assist both intracellular delivery and release of DNA, leading to very high level of transgene expression in cancer and primary cells. However, its efficiency in human lymphocytes is poor. We show here that nanocrystals of carbonate apatite, when electrostatically associated with fibronectin and/or E-cadherin-Fc, accelerated transgene delivery in a human T leukemia cell line (Jurkat). Moreover, transgene expression efficiency could be enhanced dramatically with the cell adhesive protein-embedded particles finally up to 150 times by selectively disrupting the actin filaments.

The RLF-B component of the replication licensing system is distinct from Cdc6 and functions after Cdc6 binds to chromatin.

Replication licensing factor (RLF) is an essential initiation factor that can prevent re-replication of DNA in a single cell cycle [1] [2]. It is required for the initiation of DNA replication, binds to chromatin early in the cell cycle, is removed from chromatin as DNA replicates and is unable to re-bind replicated chromatin until the following mitosis. Chromatography of RLF from Xenopus extracts has shown that it consists of two components termed RLF-B and RLF-M [3]. The RLF-M component consists of complexes of all six Xenopus minichromosome maintenance (MCM/P1) proteins (XMcm2-7), which bind to chromatin in late mitosis and are removed as replication occurs [3] [4] [5] [6] [7]. The identity of RLF-B is currently unknown. At least two factors must be present on chromatin before licensing can occur: the Xenopus origin recognition complex (XORC) [8] [9] and Xenopus Cdc6 (XCdc6) [10]. XORC saturates Xenopus sperm chromatin at approximately one copy per replication origin whereas XCdc6 binds to chromatin only if XORC is bound first [9] [10] [11]. Although XORC has been shown to be a distinct activity from RLF-B [9], the relationship between XCdc6 and RLF-B is currently unclear. Here, we show that active XCdc6 is loaded onto chromatin in extracts with defective RLF, and that both RLF-M and RLF-B are still required for the licensing of XCdc6-containing chromatin. Furthermore, RLF-B can be separated from XCdc6 by immunoprecipitation and standard chromatography. These experiments demonstrate that RLF-B is both functionally and physically distinct from XCdc6, and that XCdc6 is loaded onto chromatin before RLF-B function is executed.

Characterization of DNA synthesis and DNA-dependent ATPase activity at a restrictive temperature in temperature-sensitive tsFT848 cells with thermolabile DNA helicase B.

A temperature-sensitive mutant defective in DNA replication, tsFT848, was isolated from the mouse mammary carcinoma cell line FM3A. In mutant cells, the DNA-dependent ATPase activity of DNA helicase B, which is a major DNA-dependent ATPase in wild-type cells, decreased at the nonpermissive temperature of 39 degrees C. DNA synthesis in tsFT848 cells at the nonpermissive temperature was analyzed in detail. DNA synthesis measured by incorporation of [3H]thymidine decreased to about 50% and less than 10% of the initial level at 8 and 12 h, respectively. The decrease in the level of thymidine incorporation correlated with a decrease in the number of silver grains in individual nuclei but not with the number of cells with labeled nuclei. DNA fiber autoradiography revealed that the DNA chain elongation rate did not decrease even after an incubation for 10 h at 39 degrees C, suggesting that initiation of DNA replication at the origin of replicons is impaired in the mutant cells. The decrease in DNA-synthesizing ability coincided with a decrease in the level of the DNA-dependent ATPase activity of DNA helicase B. Partially purified DNA helicase B from tsFT848 cells was more heat sensitive than that from wild-type cells. Inactivation of DNA-dependent ATPase activity of DNA helicase B from mutant cells was considerably reduced by adding DNA to the medium used for preincubation, indicating that the DNA helicase of mutant cells is stabilized by binding to DNA.

Dietary Intake Is Associated with Occlusal Force Rather Than Number of Teeth in 80-y-Old Japanese.

There has been a growing interest in the association between the number of teeth and dietary intake in older populations. However, people around the age of 80 y have frequently lost most of their teeth, and dental prostheses replacing the missing teeth play an important role in masticatory function. Therefore, masticatory function cannot be evaluated by the number of teeth alone. The occlusal force of the complete dental arches is an index of masticatory function, reflecting not only the number of teeth, but the effect of removable dentures. The purpose of this cross-sectional study was to determine the relative importance of the number of teeth and occlusal force in association with dietary intake in 80-y-old Japanese people. This study included 760 community-dwelling Japanese people aged 79 y to 81 y. The authors measured bilateral maximal occlusal force in the intercuspal position using pressure-sensitive sheets. Removable denture wearers kept their dentures in place during the measurements. Energy-adjusted food groups and nutrient intake during the preceding month were assessed by a brief self-administered diet history questionnaire. The authors assessed linear trends in food and nutrient intake in relation to the number of teeth and occlusal force after adjusting for gender and socioeconomic status (education level, financial status, family structure, resident area and BMI). P values of < 0.05 were considered to be statistically significant. The authors found that the number of teeth was not associated with the energy-adjusted intake of any food group examined. In contrast, a decline in occlusal force was significantly associated with a lower intake of vegetables, fish and shellfish, protein, polyunsaturated fatty acids, dietary fiber and most vitamins and minerals ( P for trend < 0.05). We conclude that food and nutrient intake was more closely associated with occlusal force than the number of teeth in community-dwelling Japanese people aged 79 y to 81 y. Knowledge Transfer Statement: This cross-sectional study of older Japanese people showed that, after controlling for considerable covariates, occlusal force rather than the number of teeth is positively associated with energy-adjusted intake of vegetables, fish and shellfish, protein, polyunsaturated fatty acids, dietary fiber and most of vitamins and minerals. This means that reduced occlusal force may unconsciously lead older people toward a habitual unhealthy dietary intake. Older people have frequently lost most of their teeth and require prosthetics to restore masticatory function. Bilateral occlusal force is therefore a better measure of masticatory function than the number of remaining teeth. Our findings suggest that prosthetic rehabilitation is a significant factor in the prevention and management of chronic diseases and frailty through better dietary intake in older populations.

Molecular cloning of a cDNA encoding mouse DNA helicase B, which has homology to Escherichia coli RecD protein, and identification of a mutation in the DNA helicase B from tsFT848 temperature-sensitive DNA replication mutant cells.

DNA helicase B is a major DNA helicase in mouse FM3A cells. A temperature-sensitive mutant defective in DNA replication, tsFT848, isolated from FM3A cells, has a heat-labile DNA helicase B. In this study, we purified DNA helicase B from mouse FM3A cells and determined partial amino acid sequences of the purified protein. By using a DNA probe synthesized according to one of the partial amino acid sequences, a cDNA was isolated, which encoded a 121.5 kDa protein containing seven conserved motifs for DNA/RNA helicase superfamily members. A database search revealed similarity between DNA helicase B and the alpha subunit of exodeoxyribonuclease V of a number of prokaryotes including Escherichia coli RecD protein, but no homologous protein was found in yeast. The cDNA encoding DNA helicase B from tsFT848 was sequenced and a mutation was found between DNA/RNA helicase motifs IV and V.

Nitric oxide mediates Kupffer cell-induced reduction of mitochondrial energization in hepatoma cells: a comparison with oxidative burst.

The metabolic changes in rat hepatoma cell line, AH70 cells, after coculturing with Kupffer cells were visualized using a silicon-intensified target camera and subsequent processing with a computer-assisted digital imaging processor. In cocultured tumor cells, nonactivated Kupffer cells reduced mitochondrial energization as indicated by the decrease in the fluorescence intensity of rhodamine 123 (Rh123) and induced lipid peroxidation as shown by the dichlorofluorescein (DCF) activation. The reduction in Rh123 could be eliminated by addition of an analogue of L-arginine (NG-monomethyl-L-arginine), suggesting the involvement of nitric oxide (NO.) in the decrease in mitochondrial energization. Superoxide dismutase did not inhibit the reduction in Rh123 but significantly inhibited DCF activation. These findings indicate that the latter reaction was mediated by superoxide anion. Two h after the cells were cocultured, propidium iodide-positive, severely injured tumor cells significantly increased in number. This increase was significantly attenuated by addition of NG-monomethyl-L-arginine but not by superoxide dismutase, suggesting that NO. may be greatly involved in Kupffer cell-mediated injury of AH70 cells. In another set of experiments, the culture medium of Kupffer cells caused no significant alteration of Rh123, DCF, and propidium iodide-associated fluorescences in AH70 cells. In addition, ultrastructural observation revealed that the membrane-to-membrane attachment between Kupffer cells and tumor cells occurred within 30 min after coculturing. These results suggest that Kupffer cell-derived NO. release, triggered by the close contact with tumor cells, may induce damage to tumor cells via inhibition of mitochondrial energization.

Tooth replacement for partially dentate elders: A willingness-to-pay analysis.

OBJECTIVES: The primary aim of this study was to investigate partially dentate elders' willingness-to-pay (WTP) for two different tooth replacement strategies: Removable Partial Dentures (RPDs) and, functionally orientated treatment according to the principles of the Shortened Dental Arch (SDA). The secondary aim was to measure the same patient groups' WTP for dental implant treatment. METHODS: 55 patients who had completed a previous RCT comparing two tooth replacement strategies (RPDs (n=27) and SDA (n=28)) were recruited (Trial Registration no. ISRCTN26302774). Patients were asked to indicate their WTP for treatment to replace missing teeth in a number of hypothetical scenarios using the payment card method of contingency evaluation coupled to different costs. Data were collected on patients' social class, income levels and other social circumstances. A Mann-Whitney U Test was used to compare differences in WTP between the two treatment groups. To investigate predictive factors for WTP, multiple linear regression analyses were conducted. RESULTS: The median age for the patient sample was 72.0 years (IQR: 71-75 years). Patients who had been provided with RPDs indicated that their WTP for this treatment strategy was significantly higher (€550; IQR: 500-650) than those patients who had received SDA treatment (€500; IQR: 450-550) (p=0.003). However patients provided with RPDs indicated that their WTP for SDA treatment (€650; IQR: 600-650) was also significantly higher than those patients who had actually received functionally orientated treatment (€550; IQR: 500-600) (p<0.001). The results indicated that both current income levels and previous treatment allocation were significantly correlated to WTP for both the RPD and the SDA groups. Patients in both treatment groups exhibited little WTP for dental implant treatment with a median value recorded which was half the market value for this treatment (€1000; IQR: 500-1000). CONCLUSIONS: Amongst this patient cohort previous treatment experience had a strong influence on WTP as did current income levels. Both treatment groups indicated a very strong WTP for simpler, functionally orientated care using adhesive fixed prostheses (SDA) over conventional RPDs. CLINICAL SIGNIFICANCE: Partially dentate older patients expressed a strong preference for functionally orientated tooth replacement as an alternative to conventional RPDs.

Evaluation of Biodentine in the Restoration of Root Caries: A Randomized Controlled Trial.

There is no "gold-standard" material for the operative management of root caries. The aim of this study was to determine if the clinical performance of Biodentine would be acceptable for the restoration of root caries in older adults. A randomized controlled clinical trial was conducted comparing a calcium silicate cement (Biodentine), a high-viscosity glass ionomer cement (Fuji IX GP Extra), and a resin-modified glass ionomer cement (Fuji II LC). Of the 334 volunteers assessed for eligibility, 249 were excluded. A total of 303 lesions in 85 participants were randomized, with 151 lesions allocated to receive Biodentine, 77 to Fuji IX GP Extra, and 77 to Fuji II LC. Patients were reviewed by a calibrated dentist who was not involved in restoration placement and who was blinded to material allocation. Restorations were assessed according to a modified US Public Health Service criteria. The cumulative survival percentages after 6 mo and 1 y were 58.6% and 47.2% in the Biodentine group, 89.6% and 83.8% in the Fuji IX GP Extra group, and 89.5% and 84.9% in the Fuji II LC group, respectively. There were statistically significant differences ( χ2 test, P < 0.001) in restoration failure rates between restoration groups. There was no difference between Fuji IX GP Extra and Fuji II LC, but differences ( P < 0.001) were shown between the Fuji II GP Extra group and the Biodentine group and also between the Fuji II LC group and the Biodentine group at both time points. Based on the results of this study, Biodentine cannot be recommended for the operative management of root caries. Fuji IX GP Extra and Fuji II LC displayed similar success rates, and high-viscosity glass ionomer cement and resin-modified glass ionomer cement continue to be the best available option for the restoration of root caries ( ClinicalTrials.gov NCT01866059). Knowledge Transfer Statement: The results of this study can assist dental practitioners when selecting a restorative material for the operative management of root caries. This randomized controlled trial compared the 1-y clinical performance of a calcium silicate-based material to that of a high-viscosity glass ionomer cement and a resin-modified glass ionomer cement in the operative management of root caries. The study concluded that high-viscosity glass ionomer cement and resin-modified glass ionomer cement continue to be the best available option to dental practitioners when restoring the root surface.

Cloning of two isoforms of mouse DNA helicase Q1/RecQL cDNA; alpha form is expressed ubiquitously and beta form specifically in the testis.

We cloned cDNAs encoding mouse homologues for the human DNA helicase Q1/RecQL (human helicase Q1) which has homology with the Escherichia coli RecQ protein and found that they encode two isoforms. The two isoforms are identical over the entire sequence except for the carboxyl terminal sequence spanning less than 30 amino acids. One of the two isoforms, alpha, contains a sequence, KKRK, in the carboxyl terminus, which is also contained in human helicase Q1 and was confirmed to function as the nuclear localization signal. The other form, beta, does not contain such a sequence. Expression of mouse helicase Q1 mRNA is extremely and relatively high in the testis and the thymus, respectively. RT-PCR analysis revealed that helicase Q1alpha was expressed in all tissues tested and the beta form was expressed only in the testis. A survey of expression of Q1alpha and Q1beta mRNA in the testis after birth revealed that Q1alpha mRNA is expressed in all testes of mice aged from 7 days to 8 weeks, and the expression of Q1beta mRNA begins 14 days after birth, corresponding to the appearance of cells in the pachytene stage.

The formation of oxalate from glycolate in rat and human liver.

In this study, we attempted to elucidate the metabolic pathway and enzymes actually involved in oxalate formation from glycolate in rat and human liver. In rat liver, the formation of oxalate from glycolate appeared to take place predominantly via glyoxylate. The oxalate formation from glycolate observed with crude enzyme preparations was almost entirely accounted for by the sequential actions of glycolate oxidase and xanthine oxidase (XOD) or lactate dehydrogenase (LDH). Under the conditions used, no significant activity was attributable to glycolate dehydrogenase, an enzyme reported to catalyze the direct oxidation of glycolate to oxalate. Among the three enzymes known to catalyze the oxidation of glyoxylate to oxalate, glycolate oxidase and XOD showed much lower activities (a higher Km and lower Vmax) toward glyoxylate than those with the respective primary substrates. As to LDH, none of the LDH subunit-deficient patients examined showed profoundly lowered urinary oxalate excretion. Based on the results obtained, the presumed efficacies in vivo of individual enzymes, as catalysts of glyoxylate oxidation, and the in vivo conditions assumed to allow their catalysis of oxalate production are discussed.

Purification and Properties of a Monofunctional Imidazoleglycerol-Phosphate Dehydratase from Wheat.

Imidazoleglycerol-phosphate dehydratase (EC 4.2.1.19) activity was detected in extracts of several monocotyledonous and dicotyledonous plants using a newly developed assay method. The enzyme was purified 114,000-fold (to apparent homogeneity) from wheat germ by five chromatographic steps. Its native relative molecular weight (Mr) was determined to be 600,000 to 670,000, and it consists of identical subunits of Mr 25,500. In wheat germ, the dehydratase, unlike those of prokaryotic origin, is not associated with histidinol phosphatase activity. The reaction product was identified as imidazoleacetol phosphate (IAP) by comparing it with synthetic IAP as an authentic reference. The Km value for imidazoleglycerol phosphate was 0.36 mM at the optimal pH of 6.6. The enzyme required a reducing agent, such as 2-mercaptoethanol or dithiothreitol, and Mn2+ for maximal activity. 3-Amino-1,2,4-triazole competitively inhibited the activity with a Ki value of 46 [mu]M. The purification of imidazoleglycerol-phosphate dehydratase from wheat germ and histidinol dehydrogenase from cabbage (A. Nagai, A. Scheidegger [1991] Arch Biochem Biophys 284: 127-132) suggests that at least the second half of the histidine biosynthesis in plants is identical to that in microorganisms.

A Novel Class of Herbicides (Specific Inhibitors of Imidazoleglycerol Phosphate Dehydratase).

A new mode of herbicidal action was established by finding specific inhibitors of imidazoleglycerol phosphate dehydratase, an enzyme of histidine (His) biosynthesis. Three triazole phosphonates inhibited the reaction of the enzyme with Ki values of 40 [plus or minus] 6.5, 10 [plus or minus] 1.6, and 8.5 [plus or minus] 1.4 nM, respectively, and were highly cytotoxic to cultured plant cells. This effect was completely reversed by the addition of His, proving that the cytotoxicity was primarily caused by the inhibition of His biosynthesis. These inhibitors showed wide-spectrum, postemergent herbicidal activity at application rates ranging from 0.05 to 2 kg/ha.

The Impact of the Crown-Root Ratio on Survival of Abutment Teeth for Dentures.

Crown-root ratio (CRR) is commonly recorded when planning prosthodontic procedures. However, there is a lack of longitudinal clinical data evaluating the association between CRR and tooth survival. The aim of this longitudinal practice-based study was to assess the impact of CRR on the survival of abutment teeth for removable partial dentures (RPDs). Data were collected from 147 patients provided with RPDs at a dental hospital in Japan. In total, 236 clasp-retained RPDs and 856 abutment teeth were analyzed. Survival of abutment teeth was assessed using Kaplan-Meier methods and Cox's proportional hazard (PH) regression. The Cox PH regression was used to assess the prognostic significance of initial CRR value with adjustments for clinically relevant factors, including age, sex, frequency of periodontal maintenance programs, occlusal support area, type of abutment tooth, status of endodontic treatment, and probing pocket depth. Abutment teeth were divided into 1 of 5 risk groups according to CRR: A (≤0.75), B (0.76-1.00), C (1.01-1.25), D (1.26-1.50) and E (≥1.51). The 7-year survival rate was 89.1% for group A, 85.9% for group B, 86.5% for group C, 76.9% for group D, and 46.7% for group E. The survival curves of groups A, B, and C were illustrated to be quite similar and favorable. The multivariable analysis treating CRR as a continuous variable allowed estimation of the hazard ratio at any specific CRR value. When CRR = 0.80 was set as a reference, the estimated hazard ratio was 0.58 for CRR = 0.50 (95% confidence interval [CI], 0.36-0.91), 1.13 for CRR = 1.00 (95% CI, 0.93-1.37), 1.35 for CRR = 1.25 (95% CI, 1.02-1.80), 1.53 for CRR = 1.50 (95% CI, 1.15-2.08), or 1.95 for CRR = 2.00 (95% CI, 1.44-2.65). These practice-based longitudinal data provide information to improve the evidence-based prognosis of teeth in providing prosthodontic procedures.

Probable occurrence of toxin-susceptible G proteins in the nematode Caenorhabditis elegans.

Pertussis toxin, islet-activating protein (IAP), and cholera toxin ADP-ribosylated 40 kDa and 45 kDa proteins in membrane preparations from Caenorhabditis elegans. Proteins with the same molecular weights were recognized in the same membranes by an antibody that had been raised against a peptide common to alpha-subunits of mammalian alpha beta gamma-heterotrimeric G proteins. The antibody produced immunoprecipitation with the 40 kDa protein 32P-labeled by IAP. A 35 kDa protein immunochemically indistinguishable from the beta-component of mammalian G proteins was also found in C. elegans membranes. The membranes displayed adenylate cyclase activity which was highly sensitive to forskolin and GTP analogues, whose action was antagonized by GDP beta S. Receptor-coupled regulation of adenylate cyclase thus appears to be mediated by mammalian-type G proteins in C. elegans as well.

Neuromuscular transmission in neonatal mice injected with serum globulin of myasthenia gravis patients.

Neuromuscular transmission was studied in neonatal mice following injection with serum globulin of patients with myasthenia gravis (MG). Compared to controls, these mice showed significant reduction in successive muscle action potentials evoked by repetitive nerve stimulation, amplitude of miniature endplate potentials, and postjunctional sensitivity to acetylcholine. There was no change in evoked isometric tension, quantal content of endplate potentials, or input resistance of the endplate membrane. These results confirm earlier reports of neuromuscular block in animals following injection of globulin of myasthenic patients, and demonstrate that decrease in amplitude of evoked potentials and of miniature endplate potentials is due to reduction in sensitivity to acetylcholine rather than in input resistance of the postsynaptic membrane. These findings are compatible with a postsynaptic defect in MG caused by a humorally mediated autoimmune mechanism.

Colorectal counterpart of gastric depressed adenoma. A comparison with flat and polypoid adenomas with special reference to the development of pericryptal fibroblasts.

The histological features of 28 depressed adenomas (DAs) were compared with those of 40 flat adenomas (FAs) without a central depression and those of 29 polypoid adenomas (PAs), with special reference to the development of pericryptal fibroblasts (PCFs), using immunohistochemical staining for muscle-specific actin (HHF-35). The DAs were composed of a crowded collection of adenomatous tubules with smaller diameters than those of the PAs. With regard to PCF development, the DAs had poorly developed PCFs; PCF (-), (+), and (++) numbered 12 (43%), 16 (57%), and 0 (0%), respectively. On the other hand, the nondepressed adenomas (PAs and FAs) had well-developed PCF; PCF (-), (+), and (++) numbered 5 (7%), 35 (51%), and 29 (42%), respectively. In addition, the number of PCFs seemed to decrease in the sequence of PAs, followed by FAs and DAs. According to our results, the DAs had a characteristic histological architecture together with poorly developed PCFs features, which distinguished them from the PAs. In conclusion, the depressed adenomas were considered a subtype of the flat adenomas. The depletion of PCFs seems to correlate with the depressed growth of the adenoma.