Monitoring of genes that respond to overproduction of an insoluble recombinant protein in Escherichia coli glucose-limited fed-batch fermentations

The cellular response of Escherichia coli to overproduction of the insoluble heterologous protein alpha-glucosidase of Saccharomyces cerevisiae during a glucose-limited fed-batch fermentation was analyzed on the transcriptional and the translational levels. After the induction of the tac-regulated overexpression of the recombinant model protein, a significant but transient increase of the mRNA levels of the heat shock genes lon and dnaK could be observed. The mRNA level of the gene coding for the inclusion body-associated protein IbpB showed the strongest increase and remained at a clearly higher level until the end of the fermentation. By contrast, the mRNA levels of htrA and ppiB were decreased after induction of the alpha-glucosidase overexpression. Analysis of the soluble cytoplasmic protein fraction 3 h after induction revealed increased levels of the chaperones GroEL, DnaK, and Tig and a decrease in the protein levels of the two ribosomal proteins S6 and L9, the peptidylprolyl-cis-trans-isomerase PpiB, and the sigma(38)-dependent protein Dps. Analysis of the aggregated protein fraction revealed a remarkably inhomogeneous composition of the alpha-glucosidase inclusion bodies. N-terminal sequencing and MALDI-TOF mass spectrometry identification showed that most of these spots are fragments of the heterologous alpha-glucosidase. Host stress proteins, like DnaK, GroEL, IbpA, IbpB, and OmpT, have been found to be associated with the alpha-glucosidase protein aggregates.

Expression of the vertebrate Gli proteins in Drosophila reveals a distribution of activator and repressor activities

The Cubitus interruptus (Ci) and Gli proteins are transcription factors that mediate responses to Hedgehog proteins (Hh) in flies and vertebrates, respectively. During development of the Drosophila wing, Ci transduces the Hh signal and regulates transcription of different target genes at different locations. In vertebrates, the three Gli proteins are expressed in overlapping domains and are partially redundant. To assess how the vertebrate Glis correlate with Drosophila Ci, we expressed each in Drosophila and monitored their behaviors and activities. We found that each Gli has distinct activities that are equivalent to portions of the regulatory arsenal of Ci. Gli2 and Gli1 have activator functions that depend on Hh. Gli2 and Gli3 are proteolyzed to produce a repressor form able to inhibit hh expression. However, while Gli3 repressor activity is regulated by Hh, Gli2 repressor activity is not. These observations suggest that the separate activator and repressor functions of Ci are unevenly partitioned among the three Glis, yielding proteins with related yet distinct properties.

New mutations of the HPRT gene in Lesch-Nyhan syndrome

Lesch-Nyhan syndrome is an X-linked recessive disorder involving the purine metabolism, with resultant hyperuricemia, choreoathetosis, self-mutilation, and profound neurologic dysfunction. A deficiency of the enzyme hypoxanthine guanine phosphoribosyl-transferase is responsible for the disease. The human HPRT gene is located at Xq26-27 and consists of 57 base pairs. At least 2,000 mutations throughout the HPRT gene coding region from exon 1-9 have been reported. Four patients from three Chinese families were diagnosed with Lesch-Nyhan syndrome according to the clinical and laboratory findings. DNA studies revealed the first family (Patients 1 and 2) had a missense mutation in exon 3 of the HPRT encoding region. This novel mutation occurs in the hot spot of the HPRT gene. The second family (Patient 3) was found to have a missense mutation in exon 8 of the HPRT gene. The third family (Patient 4) carried a mutation in the splicing region of intron 4 of the HPRT gene. All three mutations were de novo.

Cyclopeptide alkaloids from Paliurus ramossisimus

Seven zizyphine A-type cyclopeptide alkaloids were isolated from the roots of Paliurus ramossisimus by the combination of centrifugal partition chromatography and conventional separation methods. The novel structures of paliurines A-F (1-6) were characterized and established on the basis of MS and elaborate NMR spectral analyses. Terminal dipeptide stereochemistry was confirmed by correlation with the synthetic dipeptides via comparison of their (13)C NMR data.

RGS4 and RGS2 bind coatomer and inhibit COPI association with Golgi membranes and intracellular transport

COPI, a protein complex consisting of coatomer and the small GTPase ARF1, is an integral component of some intracellular transport carriers. The association of COPI with secretory membranes has been implicated in the maintenance of Golgi integrity and the normal functioning of intracellular transport in eukaryotes. The regulator of G protein signaling, RGS4, interacted with the COPI subunit beta'-COP in a yeast two-hybrid screen. Both recombinant RGS4 and RGS2 bound purified recombinant beta'-COP in vitro. Endogenous cytosolic RGS4 from NG108 cells and RGS2 from HEK293T cells cofractionated with the COPI complex by gel filtration. Binding of beta'-COP to RGS4 occurred through two dilysine motifs in RGS4, similar to those contained in some aminoglycoside antibiotics that are known to bind coatomer. RGS4 inhibited COPI binding to Golgi membranes independently of its GTPase-accelerating activity on G(ialpha). In RGS4-transfected LLC-PK1 cells, the amount of COPI in the Golgi region was considerably reduced compared with that in wild-type cells, but there was no detectable difference in the amount of either Golgi-associated ARF1 or the integral Golgi membrane protein giantin, indicating that Golgi integrity was preserved. In addition, RGS4 expression inhibited trafficking of aquaporin 1 to the plasma membrane in LLC-PK1 cells and impaired secretion of placental alkaline phosphatase from HEK293T cells. The inhibitory effect of RGS4 in these assays was independent of GTPase-accelerating activity but correlated with its ability to bind COPI. Thus, these data support the hypothesis that these RGS proteins sequester coatomer in the cytoplasm and inhibit its recruitment onto Golgi membranes, which may in turn modulate Golgi-plasma membrane or intra-Golgi transport.

Observation and quantification of gas bubble formation on a mechanical heart valve

Clinical studies using transcranial Doppler ultrasonography in patients with mechanical heart valves (MHV) have detected gaseous emboli. The relationship of gaseous emboli release and cavitation on MHV has been a subject of debate in the literature. To study the influence of cavitation and gas content on the formation and growth of stable gas bubbles, a mock circulatory loop, which employed a Medtronic-Hall pyrolytic carbon disk valve in the mitral position, was used. A high-speed video camera allowed observation of cavitation and gas bubble release on the inflow valve surfaces as a function of cavitation intensity and carbon dioxide (CO2) concentration, while an ultrasonic monitoring system scanned the aortic outflow tract to quantify gas bubble production by calculating the gray scale levels of the images. In the absence of cavitation, no stable gas bubbles were formed. When gas bubbles were formed, they were first seen a few milliseconds after and in the vicinity of cavitation collapse. The volume of the gas bubbles detected in the aortic track increased with both increased CO2 and increased cavitation intensity. No correlation was observed between O2 concentration and bubble volume. We conclude that cavitation is an essential precursor to stable gas bubble formation, and CO2, the most soluble blood gas, is the major component of stable gas bubbles.

Fatal anaphylactoid shock associated with protamine for heparin reversal during anesthesia

A 19-year-old female was scheduled for elective surgery of repair of ventricular septal defect (VSD). She had no known previous food or drug allergy history. She was not previously exposed to protamine and did not have any of the risk factors pointing to protamine hypersensitivity reaction. Unfortunately there were two anaphylactoid shocks occurring during this surgery. One was caused by intravenous (i.v.) administration of antibiotics, and the other happened following i.v. drip of protamine sulfate for reversal of systemic heparinization. She had none of the risk factors suggestive of hypersensitivity to drugs and was therefore considered not at risk for such severe adverse reactions which happened. This article was to discuss the anaphylactoid shock induced by antibiotics and protamine during anesthesia, and the prevention and management of such a reaction.

The interaction between uric acid level and other risk factors on the development of gout among asymptomatic hyperuricemic men in a prospective study

OBJECTIVE

To investigate the incidence of gout and the interaction between uric acid level and other risk factors in the development of gout.

METHODS

Two hundred twenty-three asymptomatic hyperuricemic men initially studied in 1991-92 were reassessed in 1996-97. Gout was clinically diagnosed by a senior rheumatologist based on history and physical according to the clinical criteria of Wallace. Basic demographic and lifestyle variables as well as biochemical data were collected in both baseline and followup periods. Both the stability analysis and the analysis of repeated relationships were applied.

RESULTS

The 5-year cumulative incidence of gout was 18.83% (42/223). The risk factors for gout based on the analysis of repeated relationships were uric acid level, alcohol consumption, use of diuretics, and obesity. The only predictor of gout at baseline was uric acid level. After adjusting for baseline uric acid level, followup uric acid increase, persistent alcohol consumption, use of diuretics in the followup period, and body mass index increase were independent predictors for gout among asymptomatic hyperuricemic men. Excessive alcohol consumption, particularly if occasional, was the most important factor in the development of gout, even when the concentration of uric acid level was below 8 mg/dl.

CONCLUSION

Uric acid level is the key factor for prevention of gout and needs constant monitoring. Other contributing or possible etiologic factors such as alcohol consumption, diuretics use, and excess weight gain carry an increased risk of gout attack among patients with hyperuricemia.

Influence of controlled glucose oscillations on a fed-batch process of recombinant Escherichia coli

The influence of glucose oscillations on cell growth and product formation of a recombinant Escherichia coli culture producing a heterologous alpha-glucosidase was studied in fed-batch cultures in a laboratory bioreactor. Glucose oscillations were created by an on/off-feeding mode in either fast cycles (1 min) or slow cycles (4 min) and compared to a process with constant glucose addition. The study indicates that glucose oscillations influence the product stability and the overgrowth of plasmid-free cells if such cultures are not performed under continuous pressure for selection of plasmid-containing cells. Although the glucose uptake capacity decreased after induction of the recombinant alpha-glucosidase in all cultures performed, the up-growth of plasmid-free cells during the production phase was strongly inhibited by fast oscillations. In contrast, plasmid-free cells grew up when constant feeding or slow cycles were applied. Our data suggest that the various feed protocols effect the specific carbon dioxide formation rate differently, with the highest production of carbon dioxide in the cultivations with fast cycles. In connection to product formation the initial alpha-glucosidase accumulation was the same in all cultures, but the stability of the product was significantly lower in the cultivation with slow cycles. Our results from laboratory experiments are discussed in relation to the mixing situation in large-scale bioreactors.

Community based epidemiological study on hyperuricemia and gout in Kin-Hu, Kinmen

OBJECTIVE

This is a population survey conducted in 1991-92 among residents aged > or =30 years in Kin-Hu, Kinmen, with a 77.7% response rate to study the prevalence of hyperuricemia and hyperuricemia associated gout. A stratified analysis based on sex and age was used to assess the interaction and analyze the associated risk factors for hyperuricemia and gout.

METHODS

Hyperuricemia was defined as uric acid > or =7.0 mg/dl for men and > or =6.0 mg/dl for women. Gout was clinically diagnosed by a senior rheumatologist based on patient's history and examination according to the clinical criteria of Wallace. Basic demographic and lifestyle variables as well as biochemical data were collected.

RESULTS

The prevalence of hyperuricemia was 25.8% (391/1515) in men and 15.0% (250/1670) in women. The prevalence of gout among hyperuricemic subjects was 11.5% for men and 3% for women. According to age spectrum, the risk factor for hyperuricemia was hyperlipidemia in young adults (30-39 yrs); lifestyle and some clinical syndromes played a significant role in middle aged persons (40-59 yrs). The different risk factors between the sexes in middle age were alcohol consumption effect in men and menopause effect in women. Impaired renal function and use of diuretics became the important factors in the elderly (> or =60 yrs). The risk factors for gout among either the general population or subjects with hyperuricemia were concentration of serum uric acid, alcohol consumption, and central obesity.

CONCLUSION

Risk factors for hyperuricemia tended to be different with respect to sex and age. Alcohol consumption and central obesity were independent predictors of gout among hyperuricemic subjects irrespective of uric acid level.

Differential induction of tumor necrosis factor alpha and manganese superoxide dismutase by endotoxin in human monocytes: role of protein tyrosine kinase, mitogen-activated protein kinase, and nuclear factor kappaB

A mutant Escherichia coli lipopolysaccharide (LPS) lacking myristoyl fatty acid markedly stimulates the activity of manganese superoxide dismutase (MnSOD) without inducing tumor necrosis factor alpha (TNFalpha) production by human monocytes (Tian et al., 1998, Am J Physiol 275:C740.), suggesting that induction of MnSOD and TNFalpha by LPS are regulated through different signal transduction pathways. The protein tyrosine kinase (PTK)/mitogen-activated protein kinase (MAPK) pathway plays an important role in the LPS-induced TNFalpha production. In the current study, we determined the effects of PTK inhibitors, genistein and herbimycin A, on the induction of MnSOD and TNFalpha in human monocytes. Genistein (10 microg/ml) and herbimycin A (1 microg/ml) markedly inhibited LPS-induced protein tyrosine phosphorylation, phosphorylation and nuclear translocation of MAPK (p42 ERK, extracellular signal-regulated kinase), and increases in the steady state level of TNFalpha mRNA as well as TNFalpha production. In contrast, at similar concentrations, genistein and herbimycin A had no effect on the LPS-induced activation of nuclear factor kappaB (NFkappaB) and induction of MnSOD (mRNA and enzyme activity) in human monocytes. In addition, inhibition of NFkappaB activation by gliotoxin and pyrrodiline dithiocarbamate, inhibited LPS induction of TNFalpha and MnSOD mRNAs. These results suggest that (1) while PTK and MAPK are essential for the production of TNFalpha, they are not necessary for the induction of MnSOD by LPS, and (2) while activation of NFkappaB alone is insufficient for the induction of TNFalpha mRNA by LPS, it is necessary for the induction of TNFalpha as well as MnSOD mRNAs.

Negative fast atom bombardment ionization of aromatic sulfonic acids: unusual sample-matrix interaction

The most intense ion(s) in negative ion fast atom bombardment (FAB) mass spectra of 2- and 4-benzaldehyde sulfonic acid (BSA) in glycerol or 3-nitrobenzyl alcohol matrix corresponds to a covalent association of the analyte with one or two matrix molecules accompanied by the elimination of a molecule of water. The molecular ion [M - H](-), however, is of low abundance. The identity of the resulting ions [M + nA - H(2)O - H](-) (where M is the analyte and A is the matrix) was confirmed by exact mass measurement using the peak matching technique. These covalent matrix-analyte complexes were not observed when the sulfonic acid functionality in BSA was substituted with COOH, NO(2), and OH or when the sulfonic acid was in salt form. These observations indicate that the free sulfonic acid group in BSA is responsible for the covalent adduct formation. To our knowledge, analyte-matrix covalent association in negative ion FAB spectra of BSA has not been reported previously.

Serum uric acid levels in patients with cirrhosis: a reevaluation

It has been reported that the serum uric acid levels in patients with cirrhosis were decreased compared with healthy subjects. These studies suggested that the lower serum uric acid levels in cirrhotic patients were attributed mainly to an increased effective vascular volume, and consequently to an excessive renal clearance of uric acid. However, the previous observations are challenged by a recent hypothesis for the pathogenesis of hyperdynamic circulation and formation of ascites in cirrhosis. The current study was undertaken to reevaluate serum uric acid levels in patients with cirrhosis. Ninety-eight cirrhotic patients with normal renal functions were included in this study. All biochemical and hemodynamic data were utilized for analysis. The mean serum uric acid level (mean, 6.1+/-1.2 mg/dL; range, 2.7-9.1 mg/dL) was higher than that of the age- and sex-matched healthy control subjects (mean, 5.5+/-1.3 mg/dL; range, 2.9-8.1 mg/dL; p = 0.018). Using multiple regression analysis it was determined that the serum uric acid level was not related to the severity of liver disease, cardiac index, systemic vascular resistance, and hepatic venous pressure gradient but was related closely to age (r = 0.210, p = 0.026) and effective renal plasma flow (r = -0.677, p < 0.0001). Compared with cirrhotic patients without ascites, those with ascites had a significantly higher serum uric acid level (6.7+/-1.6 mg/dL vs. 5.6+/-1.7 mg/dL, p < 0.05) and lower effective renal plasma flow (396+/-125 mL/min vs. 445+/-149 mL/min, p < 0.05). In conclusion, for cirrhotic patients with normal serum creatinine levels, the current study shows that the mean serum uric acid level is higher than that of healthy control subjects. It is not related to the severity of liver failure and systemic and portal hemodynamics, but is related closely to renal functions, especially the renal plasma flow.

X-linked agammaglobulinemia presenting as juvenile chronic arthritis: report of one case

Bruton agammaglobulinemia (X-linked agammaglobulinemia, XLA), transmitted by X-linked recessive inheritance, affects only males. Twenty percent of patients with XLA may have arthritis. Septic arthritis may occur, but there is also a form of arthritis that is similar to rheumatoid arthritis or juvenile chronic arthritis. Here we report one case of XLA in a boy with non-erosive chronic right knee arthritis. There was no evidence of septic arthritis. Regular intravenous gammaglobulin replacement therapy and oral naproxen resulted in dramatic improvement in the arthritis. This case illustrates that XLA should be considered as a possible underlying cause of juvenile chronic arthritis in males.

The influence of intravenous omeprazole on intragastric pH and outcomes in patients with peptic ulcer bleeding after successful endoscopic therapy--a prospective randomized comparative trial

BACKGROUND/AIMS

The role of omeprazole in preventing rebleeding in patients with peptic ulcer bleeding after successful endoscopic therapy has been controversial. In this study, we used 3 different formulas of intravenous omeprazole in the above patients. We wished to compare the intragastric pH and outcomes among them.

METHODOLOGY

Between July 1996 and May 1997, after having obtained initial hemostasis with endoscopic therapy, a total of 20 patients with peptic ulcer bleeding (spurting/oozing/non-bleeding visible vessel: 6/4/10) received intravenous bolus of omeprazole 20 mg every 3 hours; 20 patients (3/5/12) received intravenous bolus of omeprazole 40 mg every 6 hours; and, 20 patients (5/4/11) received intravenous bolus of omeprazole 80 mg every 12 hours for 3 days. One intragastric pH meter (Gastrograph Mark III, Medical Instruments Corp. Switzerland) was used to record 24-hour intragastic pH.

RESULTS

The intragastric pH in the patients receiving omeprazole 20 mg every 3 hours was 6.1, 6.0-6.2 (mean: 95% CI); in patients receiving omeprazole 40 mg every 6 hours it was 6.4, 6.2-6.5; and, in patients receiving omeprazole 80 mg every 12 hours it was 5.8, 5.7-5.9. The duration of intragastric pH > 6.0 in omeprazole 20 mg every 3 hours was 70.9%, 57.3%-84.4% (mean: 95% CI); in omeprazole 40 mg every 6 hours it was 83.1%, 73.1%-93.1%; and, in omeprazole 80 mg every 12 hours it was 66%, 51.5%-80.4%. Patients with peptic ulcers receiving omeprazole 40 mg intravenous bolus every 6 hours had the highest intragastric pH as compared with the other 2 groups (p < 0.0001). There were no significant differences concerning rebleeding rates, volume of blood transfusion, hospital stay, numbers of operation and mortality among the 3 groups.

CONCLUSIONS

After initial hemostasis had been obtained, patients with peptic ulcer bleeding receiving 40 mg intravenous bolus every 6 hours had the highest intragastric pH. However, they had similar outcomes with the other 2 groups.

Remitting seronegative symmetrical synovitis with pitting edema (RS3PE syndrome)

A 63-year-old man presented with acute symmetrical polysynovitis associated with pitting edema of both the hands and feet. He was seronegative for rheumatoid factor and no radiologically evident erosion was noted in the joints of his hands and feet. Evaluation excluded congestive heart failure, nephrotic syndrome, and hypothyroidism as the cause of edema. Treatment with nonsteroidal anti-inflammatory drugs and low-dose steroids induced complete remission. The clinical manifestations of this patients were consistent with those of a distinctive, although rare, form of arthritis called remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome. This syndrome has a good prognosis in elderly patients.

Thyroid hormone induces activation of mitogen-activated protein kinase in cultured cells

Thyroid hormone [L-thyroxine (T4)] rapidly induced phosphorylation and nuclear translocation (activation) of mitogen-activated protein kinase (MAPK) in HeLa and CV-1 cells in the absence of cytokine or growth factor. A pertussis toxin-sensitive and guanosine 5'-O-(3-thiotriphosphate)-sensitive cell surface mechanism responsive to T4 and agarose-T4, suggesting a G protein-coupled receptor, was implicated. Cells depleted of MAPK or treated with MAPK pathway inhibitors showed reduced activation of MAPK and of the signal transducer and activator of transcription STAT1alpha by T4; they also showed reduced T4 potentiation of the antiviral action of interferon-gamma (IFN-gamma). T4 treatment caused tyrosine-phosphorylated MAPK-STAT1alpha nuclear complex formation and enhanced Ser-727 phosphorylation of STAT1alpha, in the presence or absence of IFN-gamma. STAT1alpha-deficient cells transfected with STAT1alpha containing an alanine-for-serine substitution at residue 727 (STAT1alphaA727) showed minimal T4-stimulated STAT1alpha activation. IFN-gamma induced the antiviral state in cells containing wild-type STAT1alpha (STAT1alphawt) or STAT1alphaA727; T4 potentiated IFN-gamma action in STAT1alphawt cells but not in STAT1alphaA727 cells. T4-directed STAT1alpha Ser-727 phosphorylation is MAPK mediated and results in potentiated STAT1alpha activation and enhanced IFN-gamma activity.

Influence of Helicobacter pylori on gastric secretion and gastrin release in normal Chinese subjects

BACKGROUND

Controversy exists concerning the influence of Helicobacter pylori on gastric secretion. Hyper-, normo- and hyposecretion of gastric acid in normal subjects with H pylori infection have been reported, although there is no such report for Chinese subjects. The goal of this study was to identify the effect of H pylori on gastric secretion in normal Chinese subjects.

METHODS

Twenty normal subjects with a normal upper gastrointestinal tract by endoscopy were recruited. H pylori status was assayed by a rapid urease test. Gastric secretion and gastrin release were also measured.

RESULTS

Among the subjects studied, nine were infected with H pylori. All enrolled subjects were males. Age and body weight were similar between both groups. No significant difference was found in basal acid output, maximal acid output, basal pepsin output or maximal pepsin output between the H pylori-positive group (median, 1.1 mmol/hour, 95% confidence interval 0.2-3.6 mmol/hour; 8.0, 3.0-18.3 mmol/hour; 0, -1.3-11.2 mmol/hour; and 4.1, -4.2-59.3 mmol/hour, respectively) and the H pylori-negative group (2.5, -1.3-11.3 mmol/hour; 12.2, 8.7-26.9 mmol/hour; 4.3, 1.8-13.5 mmol/hour; and 14.8, -5.7-73.0 mmol/hour, respectively). Serum basal gastrin and pepsinogen I concentration were 63.5, 50.0-78.6 pg/ml and 75.1, 50.6-89.8 ng/ml in the H pylori-positive group, and 65.9, 50.2-79.8 pg/ml and 79.1, 59.5-120.1 ng/ml in the H pylori-negative group (p > 0.05).

CONCLUSIONS

H pylori plays no role in the gastric secretion and gastrin release in normal Chinese subjects.

Effect of non-steroidal anti-inflammatory drugs on gastric and duodenal prostaglandin concentrations in patients with Helicobacter pylori infection

BACKGROUND/AIMS

Both Helicobacter pylori and non-steroidal anti-inflammatory drugs are reported to affect gastroduodenal prostaglandin synthesis. However, their influence on gastric mucosal prostaglandins remains unclear. The aim of this study was to investigate the influence of nonsteroidal anti-inflammatory drugs on mucosal prostaglandin synthesis in patients with Helicobacter pylori infection.

METHODOLOGY

We enrolled 87 Helicobacter pylori-infected patients in this study (gastric ulcer: 33, duodenal ulcer: 41, and non-ulcer dyspepsia: 13). Of them, 27 patients received non-steroidal anti-inflammatory drugs. Endoscopy was performed and biospy specimens from gastric body, antrum and duodenal bulb were assessed for Helicobacter pylori and prostaglandin concentration.

RESULTS

A significantly lower mucosal prostaglandin E2 level at gastric body (142.2 +/- 28.1 ng/mg vs. 222.0 +/- 12.4 ng/mg, mean +/- SEM) and antrum (131.3 +/- 26.4 ng/mg vs. 226.0 +/- 19.0 ng/mg) was noted in Helicobacter pylori-infected gastric ulcer patients with non-steroidal anti-inflammatory drugs ingestion than in that of patients without non-steroidal anti-inflammatory drugs ingestion (p < 0.05). Using a multivariate analysis, we found that non-steroidal anti-inflammatory drug was an independent variable affecting gastric and duodenal mucosal prostaglandin E2 synthesis in patients with Helicobacter pylori-infected gastric ulcer.

CONCLUSIONS

Non-steroidal anti-inflammatory drugs decrease gastroduodenal mucosal prostaglandin E2 synthesis in gastric ulcer patients with Helicobacter pylori infection.

Thyroid hormone promotes the phosphorylation of STAT3 and potentiates the action of epidermal growth factor in cultured cells

We have examined the effects of l-thyroxine (T4) on the activation of signal transducer and activator of transcription 3 (STAT3) and on the STAT3-dependent induction of c-Fos expression by epidermal growth factor (EGF). T4, at a physiological concentration of 100 nM, caused tyrosine phosphorylation and nuclear translocation (i.e. activation) of STAT3 in HeLa cells in as little as 10-20 min. Activation by T4 of STAT3 was maximal at 30 min (15+/-4-fold enhancement; mean+/-S.E.M.) in 18 experiments. This effect was reproduced by T4-agarose (100 nM) and blocked by CGP 41251, genistein, PD 98059 and geldanamycin, inhibitors of protein kinase C (PKC), protein tyrosine kinase (PTK), mitogen-activated protein kinase (MAPK) kinase and Raf-1 respectively. Tyrosine-phosphorylated MAPK also appeared in nuclear fractions within 10 min of treatment with T4. In the nuclear fraction of T4-treated cells, MAPK immunoprecipitate also contained STAT3. The actions of T4 were similar in HeLa and CV-1 cells, which lack thyroid hormone receptor (TR), and in TR-replete skin fibroblasts (BG-9). T4 also potentiated the EGF-induced nuclear translocation of activated STAT1alpha and STAT3 and enhanced the EGF-stimulated expression of c-Fos. Hormone potentiation of EGF-induced signal transduction and c-Fos expression was inhibited by CGP 41251, geldanamycin and PD 98059. Therefore the non-genomically induced activation by T4 of STAT3, and the potentiation of EGF by T4, require activities of PKC, PTK and an intact MAPK pathway.

Growth rate related concentration changes of the starvation response regulators sigmaS and ppGpp in glucose-limited fed-batch and continuous cultures of Escherichia coli

The entry of Escherichia coli into glucose starvation is connected to the induction of both the stringent response and the general stress response. The concentration of the corresponding response regulators ppGpp and sigmaS (RpoS, KatF) was investigated during glucose-limited growth at different growth rates and with different cultivation strategies, including fed-batch fermentation, chemostat, and a continuous-cultivation technique with computer-controlled decrease of the feeding rate (A-stat). This study confirms the model of the in vivo effect of ppGpp on sigmaS by the direct measurement of ppGpp and sigmaS levels. The response of both regulators was clearly shown in situations where a nutrient shift occurs. A correlation in the concentration of both regulators was also shown under steady-state conditions. However, during transients with slow continuous changes of the nutrient availability, this concerted reaction of ppGpp and sigmaS is less apparent, indicating the specific importance of these regulators for the adaptation of the cells to fast changes of environmental parameters.

Activation of human orbital fibroblasts through CD40 engagement results in a dramatic induction of hyaluronan synthesis and prostaglandin endoperoxide H synthase-2 expression. Insights into potential pathogenic mechanisms of thyroid-associated ophthalmopathy

Human orbital fibroblasts play a putative role in the pathogenesis of thyroid-associated ophthalmopathy (TAO). We hypothesize that the hyaluronan accumulation and inflammation in TAO derive from enhanced biosynthetic activities of orbital fibroblasts. CD40, a member of the tumor necrosis factor-alpha receptor superfamily, is a critical signaling molecule expressed by B lymphocytes. Engagement of CD40 with CD154 or CD40 ligand results in the activation of target genes. Orbital fibroblasts also display CD40. Here we report that CD40 engagement leads to substantial increases in hyaluronan synthesis in orbital fibroblasts. The increase is approximately 5-fold above control values, is comparable to the induction elicited by IL-1beta and could be attenuated with dexamethasone but not by SC 58125, a prostaglandin endoperoxide H synthase-2 (PGHS-2)-selective inhibitor. PGHS-2 is also induced by CD40 engagement in a time-dependent manner, and this is mediated through increases in levels of steady-state mRNA. The induction of PGHS-2 leads to a dramatically enhanced prostaglandin E2 production that can be blocked by SC 58125 and dexamethasone. CD40 ligand up-regulates the synthesis of IL-1alpha, and blocking this cytokine with exogenous IL-1 receptor antagonist (IL-1ra) or with IL-1alpha neutralizing antibodies partially attenuates the induction of PGHS-2. In contrast, CD40 ligand up-regulation of hyaluronan synthesis is unaffected by IL-1ra. CD40 cross-linking enhances mitogen-activated protein kinase activation, and interrupting this pathway attenuates the PGHS-2 induction. Thus the CD40/CD40 ligand bridge represents a potentially important activational pathway for orbital fibroblasts that may underlie the cross-talk between these cells and leukocytes. These findings may be relevant to the pathogenesis of TAO and provide insights into previously unrecognized, potential therapeutic targets.