PubMed Health⌕ Search

Biomedical subjects

T Berge

Publications and source records attributed to T Berge.

At least 19 recordsLinked to original sources
PubMed2004

Laboratory handling of Helicobacter pylori critically influences the results of in-vitro metronidazole resistance determination.

In-vitro metronidazole resistance rates of Helicobacter pylori determined by Etest are high, and the predictive value of metronidazole resistance is low. It was hypothesised that altered laboratory methods could reduce the overestimation of resistance and improve the predictive value of the Etest. Pre-treatment isolates (n = 150) of H. pylori from 150 patients were investigated by Etest with incubation for 72 h. Treatment with metronidazole, tetracycline and bismuth for 10 days failed to eradicate H. pylori in 23 patients. After isolate storage for 3 years, resistance determination results by agar dilution and Etest, with incubation for 72 and 31 h, were compared. The rate of metronidazole resistance was reduced significantly during storage, and instability of resistance was associated significantly with treatment outcome. Isolates that retained in-vitro resistance had significantly (p 0.008) higher treatment failure rates (n = 13; 42%) than isolates that lost resistance (n = 3; 9%). The reproducibility achieved by dual testing with agar dilution and Etest was 41% and 70% for +/- 1 and +/- 2 log2 dilutions, respectively, after incubation for 72 h, and 85% and 92%, respectively, after incubation for 31 h. Thus, the predictive value was improved from 25% to 50% by the altered laboratory conditions (p 0.04). MIC values of 2-8 mg/L signified an intermediate risk of treatment failure.

Adult↗
PubMed2002

Structure of Ocr from bacteriophage T7, a protein that mimics B-form DNA.

We have solved, by X-ray crystallography to a resolution of 1.8 A, the structure of a protein capable of mimicking approximately 20 base pairs of B-form DNA. This ocr protein, encoded by gene 0.3 of bacteriophage T7, mimics the size and shape of a bent DNA molecule and the arrangement of negative charges along the phosphate backbone of B-form DNA. We also demonstrate that ocr is an efficient inhibitor in vivo of all known families of the complex type I DNA restriction enzymes. Using atomic force microscopy, we have also observed that type I enzymes induce a bend in DNA of similar magnitude to the bend in the ocr molecule. This first structure of an antirestriction protein demonstrates the construction of structural mimetics of long segments of B-form DNA.

Bacteriophage T7↗
PubMed2001

A novel yeast system for in vivo selection of recognition sequences: defining an optimal c-Myb-responsive element.

Yeast (Saccharomyces cerevisiae) has proved to be a highly valuable tool in a range of screening methods. We present in this work the design and use of a novel yeast effector-reporter system for selection of sequences recognised by DNA-binding proteins in vivo. A dual HIS3-lacZ reporter under the control of a single randomised response element facilitates both positive growth selection of binding sequences and subsequent quantification of the strength of the selected sequence. A galactose-inducible effector allows discrimination between reporter activation caused by the protein under study and activation due to endogenous factors. The system mimics the physiological gene dosage relationship between transcription factor and target genes in vivo by using a low copy effector plasmid and a high copy reporter plasmid, favouring sequence selectivity. The utility of the novel yeast screening system was demonstrated by using it to refine the definition of an optimal recognition element for the c-Myb transcription factor (MRE). We present screening data supporting an extended MRE consensus closely mimicking known strong response elements and where a sequence of 11 nt influences activity. Novel features include a more strict sequence requirement in the second half-site of the MRE where a T-rich sequence is preferred in vivo.

Binding Sites↗
PubMed2000

Translocation-independent dimerization of the EcoKI endonuclease visualized by atomic force microscopy.

Bacterial type I restriction/modification systems are capable of performing multiple actions in response to the methylation pattern on their DNA recognition sequences. The enzymes making up these systems serve to protect the bacterial cells against viral infection by binding to their recognition sequences on the invading DNA and degrading it after extensive ATP-driven translocation. DNA cleavage has been thought to occur as the result of a collision between two translocating enzyme complexes. Using atomic force microscopy (AFM), we show here that EcoKI dimerizes rapidly when bound to a plasmid containing two recognition sites for the enzyme. Dimerization proceeds in the absence of ATP and is also seen with an EcoKI mutant (K477R) that is unable to translocate DNA. Only monomers are seen when the enzyme complex binds to a plasmid containing a single recognition site. Based on our results, we propose that the binding of EcoKI to specific DNA target sequences is accompanied by a conformational change that leads rapidly to dimerization. This event is followed by ATP-dependent translocation and cleavage of the DNA.

DNA Restriction Enzymes↗
PubMed1999

Sequence selectivity of c-Myb in vivo. Resolution of a DNA target specificity paradox.

We have investigated the basis for the striking difference between the broad DNA sequence selectivity of the c-Myb transcription factor minimal DNA-binding domain R(2)R(3) in vitro and the more restricted preference of a R(2)R(3)VP16 protein for Myb-specific recognition elements (MREs) in a Saccharomyces cerevisiae transactivation system. We show that sequence discrimination in yeast is highly dependent on the expression level of Myb effector protein. Full-length c-Myb and a C-terminally truncated protein (residues 1-360) were also included in the study. All of the tested Myb proteins displayed very similar DNA binding properties in electrophoretic mobility shift assays. Only minor differences between full-length c-Myb and truncated c-Myb(1-360) were observed. In transactivation studies in CV-1 cells, the MRE selectivity was highest at low expression levels of Myb effector proteins. However, the discrimination between MRE variants was rapidly lost with high input levels of effector plasmid. In c-Myb-expressing K-562 cells, the high degree of MRE selectivity was retained, thereby confirming the relevance of the results obtained in the yeast system. These data suggest that the MRE selectivity of c-Myb is an intrinsic property of only the R(2)R(3) domain itself and that the transactivation response of a specific MRE in vivo may be highly dependent on the expression level of the Myb protein in the cell.

Animals↗
PubMed1999

Investigation of protein partnerships using atomic force microscopy.

The origin of contrast in atomic force microscopy (AFM) lies in the probe's response to forces between itself and the sample. These forces most commonly result from changes in height as the tip is scanned over the surface, but can also originate in properties inherent in the sample. These have been exploited as further means of contrast and have spawned an array of similar imaging techniques, such as chemical force microscopy, magnetic force microscopy, and frictional force microscopy. All of these techniques use AFM as an extremely sensitive gauge to map forces at discrete sites on the surface. A natural extension of this approach is to map forces in an array, in order to create a force map. AFM can be used in aqueous or fluid environments, thus allowing the exploration of forces in biological systems under physiologically relevant conditions. By immobilizing one half of an interacting pair of proteins onto the tip and the other half onto the substrate, it is possible to investigate the electrostatic and hydrophobic interactions between them. We employed these techniques to examine the interaction between a pair of proteins of known affinity that are involved in exocytosis (NSF and alpha-SNAP) and separately to demonstrate how two-dimensional force mapping can be applied to the nuclear envelope to identify nuclear pore complexes.

Animals↗
PubMed1999

Plasma total homocysteine response to oral doses of folic acid and pyridoxine hydrochloride (vitamin B6) in healthy individuals. Oral doses of vitamin B6 reduce concentrations of serum folate.

Plasma total homocysteine response was compared in four groups of healthy individuals given orally divided doses of vitamin supplementations for a duration of 5 weeks. The vitamin supplements; A, 0.3 mg folic acid; B, 120 mg vitamin B6; C, combination of 0.3 mg folic acid and 120 mg vitamin B6 or D, 0.6 mg folic acid reduced the concentrations of plasma total homocysteine 20, 17, 32 and 24%, respectively. However, the intergroup comparisons did not show a significant difference in the effects of vitamin supplements. Multivariate analysis with correction for differences in pre-supplement values indicated a significant effect of vitamin B6 supplementation on plasma total homocysteine and serum folate. Our data show that plasma total homocysteine concentrations are reduced with low to medium divided doses of folic acid alone or in combination with vitamin B6.

Administration, Oral↗
PubMed1998

Accuracy of seven different tests for the diagnosis of Helicobacter pylori infection and the impact of H2-receptor antagonists on test results.

BACKGROUND: In this study we compared the accuracy of seven diagnostic tests in diagnosing Helicobacter pylori infection. METHODS: Over 1 year 351 consecutive dyspeptic patients were tested for H. pylori infection by means of antral biopsy specimens for the rapid urease test (RUT), culture, microscopy (acridine stain), and the laboratory urease test (LUT) and, in addition, with 14C urea breath test (UBT), IgG serology, and IgA serology (Orion Diagnostica Pyloriset New EIA-G and New EIA-A). The criterion for H. pylori infection was a minimum of three positive tests. Before being tested, 38% of the patients had used an H2-receptor antagonist (H2RA). RESULTS: Two-hundred and twenty-four patients (64%) were H. pylori-positive. The sensitivity and specificity of the tests were as follows (percentages): RUT, 85, 99; culture, 93, 100; microscopy, 81, 98; LUT, 80, 100; UBT, 95, 95; IgG serology, 99, 91; and IgA serology, 88, 91. The accuracy of the RUT and LUT was reduced in patients receiving H2RA therapy (P=0.04 and 0.01, respectively). CONCLUSIONS: Culture, UBT, and IgG serology were all superior to the other four tests in diagnosing H. pylori infection. Invasive urease-based tests were less accurate in patients receiving H2RAs.

Biopsy↗
PubMed1998

Accuracy of IgG serology and other tests in confirming Helicobacter pylori eradication.

BACKGROUND: In this study we assessed the accuracy of IgG serology and other tests in confirming Helicobacter pylori eradication. METHODS: The outcome of anti-H. pylori therapy was established by at least two of the following tests: rapid urease test (RUT), culture, 14C urea breath test (non-capsule or capsule UBT), and IgG serology (Orion Diagnostica Pyloriset New EIA-G). RESULTS: Successful H. pylori eradication was confirmed in 698 of 794 patients (88%). The percentage decrease in IgG antibody titre was related to the patients' pre-treatment IgG titre and time interval after treatment. A decrease in IgG titres of 40% or more confirmed H. pylori eradication with 100% specificity, whereas the sensitivity was 82%, 90%, 98%, and 98% 3, 4, 5, and 6 months after therapy, respectively. The 40% cut-off confirmed eradication 3 to 6 months after therapy in 328 of 339 patients (97%) with pre-treatment IgG titres of >700, in 36 of 45 patients (80%) with pre-treatment titres of 300-700, and in 5 of 12 patients (42%) with pretreatment titres of <300. The sensitivity and specificity of the other tests 2 months after treatment were as follows: RUT, 84% and 100%; culture, 88% and 100%; non-capsule UBT, 100% and 89%; and capsule UBT, 100% and 97%. CONCLUSION: A decrease in IgG antibody titre of 40% or more 3 to 6 months after therapy and the capsule 14C UBT at the 2-month follow-up were both highly accurate in confirming H. pylori eradication.

Adult↗
PubMed1998

Simplified 10-day bismuth triple therapy for cure of Helicobacter pylori infection: experience from clinical practice in a population with a high frequency of metronidazole resistance.

OBJECTIVE: To evaluate the cure rate of Helicobacter pylori infection, including the impact of in vitro metronidazole resistance (M-R), and the side effects of a simplified 10-day bismuth triple therapy in routine clinical practice. METHODS: From September 1995 to March 1996, 248 consecutive H. pylori-positive patients received 10 days of bismuth subnitrate 150 mg, oxytetracycline 500 mg, and metronidazole 400 mg, all t.id. Before treatment, upper endoscopy, including biopsy specimens for microbiological analysis and IgG serology were performed. M-R was found in 45% of females and 36% of males. At least 2 months after treatment, H. pylori status was assessed by the 14C urea breath test (n = 131), endoscopy (n = 37), urea breath test and endoscopy (n = 63), or solely by IgG serology (n = 7). Ten patients withdrew. IgG serology was performed again after 1 yr. RESULTS: H. pylori infection was cured in 205 patients: 86% by all-patients-treated analysis and 83% by intention-to-treat analysis. When patients were classified according to pretreatment metronidazole susceptibility, cure of infection was achieved in 76% of females harboring M-R strains versus 96% of those with sensitive strains (p = 0.002) and in 81% versus 88% (p = 0.34) of males with M-R versus sensitive strains, respectively. Twelve patients (5 %) had to stop treatment prematurely because of severe side effects, but eight of them were treated successfully. One case of H. pylori infection (0.6 %) was detected at 1-yr follow-up. CONCLUSIONS: Ten-day bismuth triple therapy t.i.d. was effective in curing H. pylori infection in the context of routine clinical practice. The efficacy was reduced in females harboring M-R strains.

Adult↗
PubMed1997

Highly effective second-line anti-Helicobacter pylori therapy in patients with previously failed metronidazole-based therapy.

BACKGROUND: In this study we compared the cure rates of two clarithromycin-based regimens in patients in whom anti-Helicobacter pylori therapy had previously failed. METHODS: Thirty-three patients were randomized to receive either regimen OAC (20 mg omeprazole, 750 mg amoxicillin, and 250 mg clarithromycin) or BTC (240 mg bismuth subcitrate, 750 mg oxytetracycline, and 250 mg clarithromycin), all twice daily for 10 days. A further 28 patients were all treated with OAC. Previously failed therapy included combinations of bismuth (B), omeprazole (O), tetracycline (T), metronidazole (M), amoxicillin (A), or clarithromycin (C) in BTM (n = 48), OAM (n = 13), OA (n = 7), OCM (n = 2), or BCM (n = 1). H. pylori infection was confirmed by culture of biopsy specimens, and antimicrobial susceptibility testing was performed with the E test. RESULTS: H. pylori infection was cured in all patients (n = 18) with OAC and in 8 patients (53%) with BTC (P = 0.001) in the randomized group and in 27 patients (96%) receiving OAC in the open-label group. CONCLUSIONS: Ten-day OAC is highly effective and superior to BTC in patients in whom metronidazole-based treatment has previously failed.

Adult↗
PubMed1997

Highly effective twice-daily triple therapies for Helicobacter pylori infection and peptic ulcer disease: does in vitro metronidazole resistance have any clinical relevance?

OBJECTIVES: To compare cure rates of Helicobacter pylori (H. pylori) infection, ulcer healing, and side effects of three simplified regimens of triple therapy in patients with peptic ulcer disease. METHODS: Two hundred thirty-one patients were prospectively randomized to receive either regimen OAM (omeprazole 20 mg b.i.d., amoxicillin 750 mg b.i.d., and metronidazole 400 g b.i.d.), OCM (omeprazole 20 mg b.i.d., clarithromycin 250 mg b.i.d., and metronidazole 400 mg b.i.d.), or BCM (bismuth subcitrate 240 mg b.i.d., clarithromycin 250 mg b.i.d., and metronidazole 400 mg b.i.d.), all for 10 days. Side effects were reported immediately afterward in a self-administered questionnaire. Upper endoscopy was carried out before treatment and 2 months after treatment. Three antral and three corpus biopsy specimens were analyzed microbiologically and with rapid urease test to determine the presence of H. pylori. Altogether 143 patients (62%) had an active ulcer at start of treatment. Metronidazole resistant (M-R) H. pylori strains were found in 30% of patients, while none had clarithromycin resistant (C-R) strains. RESULTS: According to intention-to-treat analysis, H. pylori cure rates were 91, 95, and 95% with OAM, OCM, and BCM, respectively (p = 0.63). In patients with metronidazole-sensitive (M-S) strains versus M-R strains, the cure rates were 96 versus 77% with OAM (p = 0.025), 94 versus 94% with OCM, and 94 versus 96% with BCM. Ulcer healing rates were 95, 94, and 92%, respectively (p = 0.91). There were no significant differences in side effects between the regimens, and only five patients (2%) had to stop the treatment prematurely. CONCLUSIONS: All treatment regimens were highly effective for cure of H. pylori infection and for ulcer healing. Metronidazole resistance reduced the efficacy of OAM, but was of no importance for the efficacy of OCM or BCM. Side effects were of minor importance.

Adult↗
PubMed1997

A comparison between omeprazole-based triple therapy and bismuth-based triple therapy for the treatment of Helicobacter pylori infection: a prospective randomized 1-yr follow-up study.

OBJECTIVES: To compare the efficacy and side effects of standard bismuth triple therapy with those of omeprazole-based triple therapy in patients with Helicobacter pylori infection and duodenal ulcer disease. METHODS: One hundred patients were prospectively recruited and randomized to receive either bismuth subnitrate 75 mg q.i.d., oxytetracycline 500 mg q.i.d., and metronidazole 400 mg b.i.d. (regimen BTM), or omeprazole 20 mg b.i.d., amoxicillin 750 mg b.i.d., and metronidazole 400 mg b.i.d. (regimen OAM), both for 14 days. Upper endoscopy (with antral biopsy specimens for microbiology and antral and corpus biopsy specimens for histology) was performed before treatment, after 2 months, and again 1 yr after treatment. Serum samples for serology (IgG) were taken. Patients with in vitro metronidazole-resistant (M-R) H. pylori strains were excluded. In a nonrandomized study, 41 patients with M-R strains were given either BTM or OAM. RESULTS: According to intention-to-treat analysis, H. pylori cure rates were 91% and 96% with BTM and OAM, respectively (p = 0.45). In the BTM group, the mean total side effect score was higher (p < 0.001), and more severe side effects were reported (32% vs. 4%, p < 0.001). In the nonrandomized group of patients with M-R strains, H. pylori cure rates were 88% and 67% with BTM and OAM, respectively. All of the successfully treated patients were still H. pylori-negative after 1 yr. CONCLUSIONS: Both treatment regimens were highly effective in curing H. pylori infection in patients with metronidazole-sensitive strains. Omeprazole-based triple therapy was tolerated better than standard bismuth-based triple therapy.

Adult↗
PubMed1993

[Encopresis--in a child psychiatric treatment regime].

The evidence to date suggests a multi-factoral aetiology for encopresis, especially in cases where it is part of a psychiatric disorder. A physiological predisposition, the age at which bowel training is begun, the parent-child relationship and environmental stresses are influential. Thus no single treatment will suffice for the varieties of encopresis encountered in child psychiatric practice. This paper presents a programme used at a child psychiatric unit and embodying several methods of treatment: use of lavement, laxatives and softeners, counselling, behaviour modification and environmental therapy.

Child↗
PubMed1989

Porokeratosis punctata palmaris et plantaris. A new entity?

Seven members from three generations of a Saudi family presented with porokeratosis punctata palmaris et plantaris (PPPP). In our series of patients, the disorder began in their early 20s, seemed to be transmitted as a dominant trait, and affected males only. The elementary lesion was a tiny keratotic spine, and the involvement was strictly limited to the volar aspects of the hands and to the soles of the feet. Histological studies showed a columnar parakeratosis that resembled the cornoid lamella of porokeratosis, but other clinical and histological traits tended to make PPPP an entity that was distinct from true porokeratosis. There have been only six reports in the literature on genuine PPPP before this series.

Adult↗