A supervised learning neural network coprocessor for soft-decision maximum-likelihood decoding

A supervised learning neural network (SLNN) coprocessor which enhances the performance of a digital soft-decision Viterbi decoder used for forward error correction in a digital communication channel with either fading plus additive white Gaussian noise (AWGN) or pure AWGN has been investigated and designed. The SLNN is designed to cooperate with a phase shift keying (PSK) demodulator, an automatic gain control (AGC) circuit, and a 3-bit quantizer which is an analog to digital convertor. It is trained to learn the best uniform quantization step-size Delta (BEST) as a function of the mean and the standard deviation of various sets of Gaussian distributed random variables. The channel cutoff rate (R(0)) of the channel is employed to determine the best quantization threshold step-size (Delta(BEST)) that results in the minimization of the Viterbi decoder output bit error rate (BER). For a digital communication system with a SLNN coprocessor, consistent and substantial BER performance improvements are observed. The performance improvement ranges from a minimum of 9% to a maximum of 25% for a pure AWGN channel and from a minimum of 25% to a maximum of 70% for a fading channel. This neural network coprocessor approach can be generalized and applied to any digital signal processing system to decrease the performance losses associated with quantization and/or signal instability.

Beneficial influence of glycemic control upon the growth and function of transplanted islets

Syngeneic transplantation of 200 mouse islets under the kidney capsule usually fails to cure streptozocin-induced diabetes. We hypothesized that this number of islets, if engrafted in a normoglycemic environment, could expand their mass and improve their function to restore normoglycemia. Therefore, 200 freshly isolated mouse islets were transplanted under the capsule of each kidney of diabetic mice. Two weeks after transplantation, the recipients were normoglycemic, and one of the two grafts was removed. Removal of the graft was followed by transient hyperglycemia. At day 14 after graft removal, the beta-cell mass and insulin content of the remaining graft had increased 2.3- and 2.1-fold, respectively. At day 3 after graft removal, the replication rate of beta-cells increased threefold, and the mean individual beta-cell cross-sectional area, an indicator of cell size, was also increased. Perfusion of the kidney bearing the remaining graft showed biphasic insulin responses to high glucose and arginine 14 days after one graft removal. These data indicate that maintaining a period of near-normoglycemia after islet transplantation enhances the performance of an islet graft that would otherwise be expected to fail.

Coexistence of spinal arteriovenous malformation and ankylosing spondylitis--are they related?

A 50-year-old man with long standing ankylosing spondylitis developed cauda equina syndrome, which was found to be coexistent with a spinal arterio-venous malformation. Paraplegia ensured following an acute exacerbation of back pain along with an attack of uveitis. Vasculitis changes were found on resected abnormal vessels.

In situ glucose uptake and glucokinase activity of pancreatic islets in diabetic and obese rodents

The present study evaluated the involvement of glucose transport and phosphorylation in glucose-stimulated insulin release from pancreatic islets. Using quantitative histochemical techniques, we investigated basal islet glucose content, islet glucose uptake in situ during acute extreme experimental hyperglycemia, and islet glucokinase activity in several animal models of diabetes and obesity. The basal islet glucose content in anaesthetized diabetic or obese rodents was either the same or higher than that in their relevant controls. The rate of glucose uptake of islet tissue in these animals after an i.v. glucose injection was different. The db+/db+ mouse and the obese Zucker rat exhibited significantly reduced islet glucose uptake rates. RIP-cHras transgenic mice, BHE/cdb rats and partially pancreatectomized rats showed normal islet glucose uptake rates. The activity of islet glucokinase was increased to a different degree related to the blood glucose level. All five animal models of diabetes or obesity exhibited either a delay or a reduction of insulin release in response to supra maximal glucose stimulation. Our results indicate that the impairment of glucose-induced insulin release in diabetes is not consistently associated with a reduction of islet glucose uptake nor a change of glucokinase activity.

Transcriptional regulation of the human Wilms' tumor gene (WT1). Cell type-specific enhancer and promiscuous promoter

The Wilms' tumor gene, WT1, is expressed in few tissues, mainly the developing kidney, genitourinary system, and mesothelium, and in immature hematopoietic cells. To develop an understanding of the role of WT1 in development and tumorigenesis, we have identified transcriptional regulatory elements that function in transient reporter gene constructs transfected into kidney and hematopoietic cell lines. We found three transcription start sites of the WT1 gene and have identified an essential promoter region by deletion analysis. The WT1 promoter is a member of the GC-rich, TATA-less, and CCAAT-less class of polymerase II promoters. Whereas the WT1 promoter is similar to other tumor suppressor gene promoters, the WT1 expression pattern (unlike Rb and p53) is tissue-restricted. The WT1 GC-rich promoter is promiscuous, functioning in all cell lines tested, independent of WT1 expression. This finding suggests that the promoter is not tissue-specific, but that tissue-specific expression of WT1 is modulated by additional regulatory elements. Indeed, we have identified a transcriptional enhancer located 3' of the WT1 gene > 50 kilobases downstream from the promoter. This orientation-independent enhancer increases the basal transcription rate of the WT1 promoter in the human erythroleukemia cell line K562, but not in any of the other cell lines tested.

Ribozyme-mediated attenuation of pancreatic beta-cell glucokinase expression in transgenic mice results in impaired glucose-induced insulin secretion

Phosphorylation of glucose to glucose 6-phosphate by glucokinase (GK; EC 2.7.1.2) serves as a glucose-sensing mechanism for regulating insulin secretion in beta cells. Recent findings of heterozygous GK gene mutations in patients with maturity-onset diabetes of the young (MODY), a form of type II (non-insulin-dependent) diabetes characterized by autosomal dominant inheritance, have raised the possibility that a decrease in beta-cell GK activity may impair the insulin secretory response of these cells to glucose. To generate an animal model for MODY we have expressed in transgenic mice a GK antisense RNA with a ribozyme element under control of the insulin promoter. Mice in two independent lineages had about 30% of the normal islet GK activity. Insulin release in response to glucose from in situ-perfused pancreas was impaired; however, the plasma glucose and insulin levels of the mice remained normal. These mice are likely to be predisposed to type II diabetes and may manifest increased susceptibility to genetic and environmental diabetogenic factors. They provide an animal model for studying the interaction of such factors with the reduced islet GK activity.

Nuclear matrix proteins in human colon cancer

The nuclear matrix is the nonchromatin scaffolding of the nucleus. This structure confers nuclear shape, organizes chromatin, and appears to contain important regulatory proteins. Tissue specific nuclear matrix proteins have been found in the rat, mouse, and human. In this study we compared high-resolution two-dimensional gel electropherograms of nuclear matrix protein patterns found in human colon tumors with those from normal colon epithelia. Tumors were obtained from 18 patients undergoing partial colectomy for adenocarcinoma of the colon and compared with tissue from 10 normal colons. We have identified at least six proteins which were present in 18 of 18 colon tumors and 0 of 10 normal tissues, as well as four proteins present in 0 of 18 tumors and in 10 of 10 normal tissues. These data, which corroborate similar findings of cancer-specific nuclear matrix proteins in prostate and breast, suggest that nuclear matrix proteins may serve as important markers for at least some types of cancer.

[Modelling and analysis of interactions of flecainide with cardiac sodium channels]

Based on the gate-related receptor hypothesis, modelling and analysis of the kinetics of interactions of flecainide with cardiac sodium channels and the gate-related receptor bound by the drug were performed by computer simulation. Model-predicted apparent rates of onset of flecainide (1 mumol.L-1) blocking were 0.586, 0.128, 0.071, 0.042 and 0.030 AP-1 respectively at stimulation frequencies of 0.1, 0.5, 1.0, 2.0, and 3.3 Hz. The estimated time constant of recovery from block by flecainide was 17.45 s. These results are in agreement with documented experimental data. Analysis of gate-related receptor showed that the binding and unbinding of flecainide are modulated by activation process. No shift of h infinity curve but a significant decrease of m infinity 3 curve was found in the presence of flecainide (1 mumol.L-1). The results suggest that flecainide binds to the activation gate-related receptor and may be trapped in the channel by the activation gate.

[The hemodynamic and ventilatory effects between Trendelenburg and reverse Trendelenburg position during laparoscopy with CO2-insufflation]

Thirty ASA class I female patients underwent gynecologic pelvioscopy and laparoscopic cholecystectomy were included in this study. All of them received general anesthesia and certain volume of CO2 pneumoperitoneum. We evaluated the effect of positioning (Trendelenburg as group I and reverse Trendelenburg as group II) on hemodynamic parameters and ventilation. The hemodynamic parameters, ventilation, and arterial blood gas were determined at the following stages: (1) after 10 minutes of normoventilation and before CO2 pneumoperitoneum (as control), (2) 5 minutes after CO2 pneumoperitoneum and positioning, (3) 25 minutes after positioning, (4) 50 minutes after positioning, (5) 10 minutes after resumption of supine position and decompression of abdomen. Arterial blood pressure, heart rate, minute volume, end-tidal CO2, oxygen saturation and blood gas analysis were taken during normoventilation. We found that there was no statistical difference between either group in respect to hemodynamic parameters. For the ventilation, both groups had appropriate SpO2 during the period of CO2 pneumoperitoneum, but PaCO2 was significantly increased in group I 25 min after CO2 pneumoperitoneum and Trendelenburg positioning. Nonetheless, end-tidal CO2 was not significantly increased. pH value and PaCO2 did respectively decrease and increase significantly in group I 50 min after Trendelenburg position. However, no change was found in end-tidal CO2. All data were not significantly different after resumption of supine position and decompression of abdomen. Conclusively, except that pH and PaCO2 had changed after a period of Trendelenburg positioning with CO2 pneumoperitoneum, the patients who underwent laparoscopic surgery with normoventilation have no hemodynamic and respiratory change.(ABSTRACT TRUNCATED AT 250 WORDS)

Phagocytosis of platelet in coronary heart disease patients with blood-stasis syndrome

Phagocytosis of platelets was studied under electronmicroscope in 36 healthy persons and 64 coronary heart disease (CHD) patients with blood-stasis syndrome (BSS). The result showed that both the number of latex particles phagocytized by platelet and platelets which phagocytized latex particles were decreased in CHD with BSS. It was also found in this group that most of the platelets having active-phagocytosis were of medium size. The proportion of large platelets containing plentiful glycogen granules was much more in CHD patients with BSS and the shapes of platelets were changed readily with active exocytosis and aggregations. Therefore the present findings of disability of platelet phagocytosis might be considered the basic change in CHD with BSS.

AN-132 block of cardiac sodium channels: a gate-related receptor analysis

Based on the gate-related receptor hypothesis, an analysis of kinetics of AN-132, a new antiarrhythmic agent, blockade of cardiac sodium channels and the gate-related receptor which is bound by the drug was performed by computer simulation. Model-predicted apparent rates of onset of AN-132 (30 mumol/L) blocking were 0.051, 0.038, and 0.034 AP-1 at stimulation frequencies of 1.0, 2.0 and 3.0 Hz, respectively. The time constant of recovery from block by AN-132 at resting potential -90 mV was 39.5 s. These findings are in agreement with those experimental data documented. The analysis of gate-related receptor shows that AN-132 binds the inactivation gate-related receptor, and the binding and unbinding are modulated by the inactivation process.

Expansion and differentiation of human hematopoietic cells from static cultures through small-scale bioreactors

Maintenance of the progenitor cells responsible for hematopoiesis has generally been accomplished using a feeder layer of stromal cells in stationary culture. Here, we compared the expansion of the total cell and progenitor cell populations using low-density mononuclear cells (LDMCs) obtained from human bone marrow in static culture (T-flasks) and in different cell culture bioreactors designed for the scale-up of mammalian cells. Static cultures were performed without the presence of a previously established stromal cell layer. Expansion of marrow in all cases was accomplished through the use of added cytokines such as IL-3, GM-CSF, and c-kit ligand. The results for the total cell expansion in static culture ranged from 4.4- to 32-fold. The cell number increase was affected by such factors as patient to patient variability, freeze-thawing, and the combination of cytokines used. Due to widespread use and the small amount of marrow needed, static cultures were used as a basis for comparison with other expansion systems. The cell culture systems used to evaluate the scale-up of marrow cultures included suspension, microcarrier, airlift, and hollow fiber bioreactors. Using identical media, cytokines, and feed schedules, LDMCs in the suspension bioreactor expanded to a value of 1.6 compared to a normalized value of 1.0 for static cultures for the two runs investigated. Expansion results for microcarrier cultures averaged 0.75 when compared to static cultures. A cell number increase in the airlift bioreactor resulted in an expansion which was 0.70 of the control static culture. Granulocyte-macrophage and erythroid progenitor assay data were also evaluated for the suspension, microcarrier, and airlift bioreactors.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of action of sodium channel blocker: gate-related receptor hypothesis

A new hypothesis on mechanisms of action of the sodium channel blocker, the gate-related receptor hypothesis, has been proposed in this paper. Furthermore, a mathematic model and parameter estimation procedure for the kinetics analysis have also been given. Using the model and procedure, modeling and analyzing of cardiac sodium channel blockade by lidocaine and dauricine have been performed. The model-estimated results were not only coincident with those documented, but also provided some new information which may be helpful for understanding mechanism of blocking action of both drugs on sodium channels. The studies suggested that the gate-related receptor hypothesis is good for the elucidation of mechanisms of action of the sodium channel blocker.

The loss of GLUT2 expression by glucose-unresponsive beta cells of db/db mice is reversible and is induced by the diabetic environment

Glucose-induced insulin secretion by beta cells of diabetic db/db mice was studied by a pancreas perfusion technique, and the levels of GLUT2 protein in pancreatic islets were assessed by immunofluorescence microscopy and protein blot analysis. Beta cells from diabetic mice had a high basal rate of insulin secretion; they did not respond to glucose stimulation but displayed a normal secretory response to arginine. At the same time, GLUT2 expression by db/db islets was lost whereas beta cells from nondiabetic db/+ mice expressed high levels of this transporter. GLUT2 levels in liver or kidney of diabetic mice were, however, mostly unaltered. Transplanting islets from db/db mice under the kidney capsule of db/+ mice restored normal GLUT2 levels. Conversely, transplantation of db/+ islets into db/db mice induced the disappearance of GLUT2 expression. When islets from db/+ mice were transplanted under the kidney capsule of streptozocin-diabetic mice, the immunodetection of GLUT2 also disappeared. We conclude that: (a) GLUT2 expression is decreased in glucose-unresponsive beta cells from db/db mice; (b) the decreased expression of GLUT2 is reversible; (c) the loss of GLUT2 expression is induced by the diabetic environment of db/db and streptozocin-induced diabetic mice. These observations together with previously published data suggest that a factor different from glucose or insulin regulates the beta cell expression of GLUT2.

[Val12] HRAS downregulates GLUT2 in beta cells of transgenic mice without affecting glucose homeostasis

Glucose-induced insulin release from pancreatic beta cells depends on the beta-cell metabolism of glucose, which generates intracellular signals for secretion. The beta-cell glucose transporter isotype GLUT2 and the glucose phosphorylating enzyme glucokinase have both been implicated in coupling insulin secretion to extracellular glucose levels. Here we present evidence that a pronounced decrease in beta-cell GLUT2 has no immediate effect on glucose homeostasis. Analysis of transgenic mice overexpressing human [Val12]HRAS oncoprotein under control of the insulin promoter reveals a great reduction in plasma-membrane GLUT2 levels. These mice are nonetheless able to maintain normal fed and fasting plasma glucose and insulin levels for a period of several months. Insulin secretion studied in isolated islets and the perfused pancreas is characterized by a normal incremental response to increasing glucose concentrations. Glucose metabolism, as measured by glucose phosphorylation and oxidation in isolated islets, shows a normal dose dependence on extracellular glucose concentrations. These findings suggest that normal GLUT2 expression in beta cells is not essential for glucose sensing. The transgenic mice provide an experimental system for studying the role of glucose phosphorylation in regulation of insulin release in the absence of GLUT2.

Computer simulation of metoclopramide block of cardiac sodium channels

Based on the gate-related receptor hypothesis, a quantitative study on kinetics and state-dependency of metoclopramide (Met) blockade of cardiac sodium channels was performed by computer simulation. The characteristics of Met, a sodium channel blocker modulated simultaneously by both activation and inactivation gates were described and analyzed for the first time. The time constant of recovery from blocking for Met at resting potential -85 mV was 2.82 s, which was increased during depolarization or hyperpolarization. Its apparent rate of onset of blocking was 0.49 AP-1 at a stimulation frequency of 2.0 Hz. A concentration-dependent shift of h infinity curve was found at doses higher than 100 mumol/L Met. This study provides a new test and verification for our gate-related receptor hypothesis.

Activation of globin gene expression by cDNAs from induced K562 cells. Evidence for involvement of ferritin in globin gene expression

We have isolated non-globin cDNA clones specific for erythroid differentiation from K562 human erythroleukemia cells and have identified those that may regulate globin gene transcription. A cDNA library was constructed from K562 cells induced by hemin for production of embryonic and fetal hemoglobins and screened against cDNA from uninduced K562 cells. Full-length clones specific for induced K562 cells were ligated into a eukaryotic expression vector and transfected into HeLa cells to allow for production of the corresponding coded polypeptide. The ability to increase epsilon- or gamma-globin promoter activity was identified using cotransfection with a second vector containing a globin gene promoter fused to a reporter gene. Six of the induced K562-specific clones exhibited the ability to increase the levels of the reporter genes, bacterial chloramphenicol acetyltransferase and human growth hormone. Sequencing analyses of these clones indicated that five were homologous to ferritin heavy and light chains and one had no homology with known DNA or protein sequences. The ferritin light chain cDNA had the greatest effect on globin gene promoter activation, increasing the gamma-globin promoter activity by 6-8-fold. The activation of the globin gene promoter in the absence of globin gene translation suggests that ferritin (or iron) may have a direct role in globin gene transcription. The subtractive library cloning strategy has enabled us to isolate cDNA clones that activate specific gene promoter without the requirement of direct DNA binding. This approach may allow further identification of the genes encoding proteins that are involved in the control of erythropoiesis.

[Modelling and kinetic analysis on changrolin block of cardiac Na+ channels]

Modelling and kinetic analysis on changrolin (CRL) blockade of cardiac Na+ channels based on the model of gate-related receptor hypothesis were performed by using computer simulation. A simple procedure suitable for analyzing steady-state blocking data was developed and used in the present studies. CRL blocks activated Na+ channels, and with the onset rate of 0.0347 AP-1 at driving rate of 1.0 Hz. The time constant of recovery from block at resting potential of -81 mV was 43.29 s, and increased with hyperpolarization, which suggested that CRL might be trapped in channel by activation gate. The studies also showed no shift on the h infinity curve in the presence of CRL. All these studies lead us to suggest that the binding site of CRL in Na+ channel is activation gate-related receptor site.

[Effects of sodium 18 beta-glycrrhetinic acid on the production of active oxygen species and the concentration of intracellular free Ca2+ in rat neutrophils]

The effects of sodium 18 beta-glycyrrhetinic acid (SGA) on the production of active oxygen species (AOS) and the concentration of intracellular free Ca2+ ([Ca2+]i) in the rat neutrophils were studied by the methods of luminoldependent chemiluminescence and calcium indicator Fura-2 loading. The results showed that SGA 0.8-12.7 mumol.L-1 selectively inhibited calcium inophore A-23187-stimulated AOS production with IC50 1.4 mumol.L-1, while SGA 25.4-203 mumol.L-1 stimulated neutrophils to generate AOS and potentiated the action of chemotactic peptide f-MLP on inducing AOS production. SGA 25.4-203 or 6.3-50.7 mumol.L-1 depressed the [Ca2+]i rise in neutrophils stimulated by A-23187 or f-MLP; in the contrast, verapamil or diltiazem has higher effective concentration more than 100 or 200 mumol.L-1 to f-MLP and left [Ca2+]i rise induced by A-23187 unaffected. SGA 101.5-203 mumol.L-1 also caused [Ca2+]i rise in neutrophils. The result analysis indicate that the effect of SGA on AOS production has no relationship with its regulation to [Ca2+]i in neutrophils.

Long term and large-scale cultivation of human hepatoma Hep G2 cells in hollow fiber bioreactor

Long-term and large scale cultivation of an anchorage-dependent cell line using an industrial scale hollow fiber perfusion bioreactor is described. Hep G2 cells (a human hepatoma cell line) were cultivated in an Acusyst-P (Endotronic) with a total fiber surface area of 7.2 m2 6 x 1.2m2) to produce Hep G2 crude conditioned medium (CCM). Pretreatment of the cellulose acetate hollow fibers with collagen enhances the attachment of the anchorage-dependent cells. We have succeeded in growing the Hep G2 cells in an antibiotics- and serum-free IMDM medium, supplemented with 50 micrograms/ml of Hep G2 CCM protein at inoculation. The Hep G2 cells replicate and secrete CCM protein in quantities comparable to those produced in DMEM containing 10% fetal calf serum (FCS). The highest CCM protein productivity during the 80-day cultivation was 1.1 g/day with a total of 30 g of protein accumulated. Hep G2 CCM (20-40 micrograms protein/ml) was comparable to or even better than 10% FCS in supporting the growth of Molt-4 (a human T leukemia cell line) and FO (a mouse myeloma cell line) cells in vitro. The availability of this large amount of Hep G2 CCM will aid the further purification and characterization of growth factor(s) which could be used as serum substituents.

Protective role of BCG in the rabbit model of mesangial proliferative glomerulonephritis

A study was designed to investigate whether BCG could play a protective role in a rabbit model of mesangial proliferative glomerulonephritis. Fifteen rabbits were immunised with multiple injections of bovine serum albumin and their mononuclear phagocytic system was depressed by endotoxin from E. coli. The rabbits were divided into two groups: Group 1 (n = 7) received intravenous BCG from 3 weeks prior to the pathogenic immunisation and until the end of this period; Group 2 (n = 8) acted as a control and received normal saline. In the BCG group circulating immune complex (CIC) titres were significantly reduced, rabbit IgG deposition in glomeruli was significantly less, and mean glomerular cell counts were significantly less than those in the control group. We conclude that BCG stimulates the mononuclear phagocytic system to remove CIC and reduce the deposition of immune complexes in glomeruli, thereby mitigating the inflammatory response.

Association of imperforate anus with short colon: a report of eight cases

Eight cases of imperforate anus with short colon were seen in our hospital from April 1982 to December 1987. Five were boys, three were girls, and their ages ranged from 2 days to 2 years. The international literature about this kind of disease was reviewed. The disease's name, embryology, diagnoses, differential diagnosis, treatment, and prognosis are discussed herein. We suggest that this case, which was not combined with exstrophy of the bladder and/or intestine, be called association of imperforate anus with short colon (AIASC). Other cases, combined with exstrophy of the bladder and/or intestine could be called, association of imperforate anus with exstrophy splanchnica (AIAES). This distinction is necessary because each group differs in symptoms, signs, diagnosis, treatment, and prognosis.