Biomedical subjects

F Jørgensen

Publications and source records attributed to F Jørgensen.

At least 37 records · Page 2Linked to original sources

PubMed1999

Helicobacter pylori detection in human biopsies: a competitive PCR assay with internal control reveals false results.

A polymerase chain reaction assay (PCR) for the diagnosis of Helicobacter pylori in human gastric biopsies was developed. To prevent false-negative results while performing PCR on human tissues, an internal control is necessary. Primer set ACT1-ACT2 which specifically amplifies a 542-bp fragment of the 16S rRNA gene of H. pylori was used. dUTP and hot-start were used to prevent false-positives from carryover of previous products and avoid non-specific extension products. A competitive internal control DNA fragment was constructed to detect the presence of inhibitors. Biopsies from 101 unselected patients with gastric symptoms were tested. PCR results were compared with results from microscopy of histological sections and conventional culturing for H. pylori. Forty-two percent of the biopsies were found to contain compounds inhibiting the PCR. The addition of the internal control assures the performance of the PCR assay and is an important quality control parameter.

Adolescent↗

PubMed1998

Construction and analysis of luxCDABE-based plasmid sensors for investigating N-acyl homoserine lactone-mediated quorum sensing.

Plasmid reporter vectors have been constructed which respond to activation of LuxR and its homologues LasR and RhlR (VsmR) by N-acyl homoserine lactones (AHLs). The expression of luxCDABE from transcriptional fusions to PluxI, PlasI and PrhlI respectively, occurs in the presence of activating AHLs. A profile of structure/activity relationships is seen where the natural ligand is most potent. The characterisation of individual LuxR homologue/AHL combinations allows a comprehensive evaluation of quorum sensing signals from a test organism.

4-Butyrolactone↗

PubMed1998

Swelling-activated potassium currents of Ehrlich ascites tumour cells.

The K+ and Cl- currents activated by Ca2+-ionophore treatment or by hypotonic cell swelling have been studied in Ehrlich ascites tumour cells by the patch-clamp technique. A charybdotoxin-inhibitable K+ current was activated by increasing intracellular Ca2+ concentration. In contrast, the K+ current activated by cell swelling was insensitive to charybdotoxin as well as to apamin, suggesting that channels different from those sensitive to Ca2+ are responsible for regulatory volume adjustments in these cells. The magnitude of the K+ and Cl- currents activated by hypotonic challenge was markedly temperature-dependent, possibly reflecting the temperature-dependence of enzymes involved in the intracellular signalling of cell volume regulation.

Animals↗

PubMed1998

Pathogenicity in isolates of Salmonella enterica serotype Enteritidis PT4 which differ in RpoS expression: effects of growth phase and low temperature.

Experiments with 2 wild type isolates of Salmonella enterica serotype Enteritidis PT4, which differed in RpoS expression, tolerance to certain hostile environments and pathogenicity, found that changes in in vitro acid, heat, or peroxide tolerance had no effect on the ability of the isolates to multiply in the spleens of C57/BL7/J mice infected orally. Thus, with the pathogenic RpoS-positive isolate, the infectivity of log phase chilled cells, which are profoundly acid-sensitive, was the same as that of non-chilled stationary phase cells which are acid-tolerant. Similarity the infectivity of the RpoS-negative, sensitive isolate, was not enhanced by increases in any tolerance. The ability to survive on surfaces, like infectivity, was also largely unaffected by either growth phase or cold exposure. These two attributes may thus be related and, given that the pathogenic PT4 isolate is capable of prolonged survival and the nonpathogenic isolate survives poorly, survival could serve as a potential marker of pathogenicity. Although the pathogenicity of the two isolates was very different, they showed an almost identical increase in acid tolerance following culture at pH 4.0 for up to 60 min.

Acids↗

PubMed1998

The diagnostic value of oesophageal radionuclide transit in patients admitted for but without acute myocardial infarction.

The use of radionuclide transit (RT) as a screening test for chest pain of oesophageal origin has been debated. The aim of this study was to determine the value of RT as a screening test for oesophageal disorders in comparison with oesophageal manometry in patients admitted with acute chest pain but without acute myocardial infarction (non-AMI patients), and to assess the frequency of oesophageal disease present in these patients. A total of 222 non-AMI patients entered the study. An extensive examination programme comprised noninvasive cardiac studies, pulmonary studies, a careful physical examination of the musculoskeletal system, and oesophago-gastric examinations including endoscopy, pH monitoring of the oesophagus and a Bernstein test. In 91% of the patients one or more diagnoses were obtained. Based on clinical and laboratory data a 'consensus' diagnosis was made. With manometry as the reference RT had a poor sensitivity (35%) but an acceptable specificity (82%). With the consensus diagnosis as the gold standard the sensitivities of both manometry and RT were poor (29%), whereas the specificity of RT, but not of manometry, was very high (97%). Gastrointestinal diagnoses were found in 57% of the patients. In conclusion, none of the applied oesophageal examinations are valuable as single screening tests. Both RT and manometry have low sensitivities. RT may be used as a cheap, noninvasive and rapid supplementary examination. When positive, it strongly supports further invasive studies of the oesophagus in non-AMI patients with unexplained chest pain.

Chest Pain↗

PubMed1998

An analysis of seven different methods to diagnose Helicobacter pylori infections.

BACKGROUND: It has been debated which diagnostic test should be preferred for the diagnosis of Helicobacter pylori in patients with gastroduodenal diseases. METHODS: The H. pylori infection was diagnosed prospectively in 97 untreated patients. H. pylori was diagnosed by means of tests based on five different principles: 1) culture, 2) microscopy (HLO), 3) urease activity (urea breath test (UBT) and urease test on biopsy specimens (CLO test)), 4) DNA detection (polymerase chain reaction (PCR)), and 5) IgG antibody detection (enzyme-linked immunosorbent assay (EIA) and Western blotting (WB)). RESULTS: This study showed that two positive tests out of five tests, based on different principles, were most reliable for predicting the H. pylori infection. Most tests had specificities and predictive values for a negative result greater than 90%. The most important difference between the tests was the sensitivity and the predictive value for a positive result (PPV). WB, HLO, UBT, and PCR had sensitivities and PPV greater than 75%. CONCLUSIONS: The non-invasive tests UBT and WB are reliable, both alone and in combination, and they are recommended for the pre-endoscopic diagnosis of H. pylori. WB is recommended as a confirmative test for antibody detection by EIA. When patients have an upper endoscopy, we recommend taking biopsy specimens for culture and histology because of the additional information obtained about susceptibility, virulence determinants, and morphology, including the degree of inflammation.

Adult↗

PubMed1998

Cloning of the Lactococcus lactis adhE gene, encoding a multifunctional alcohol dehydrogenase, by complementation of a fermentative mutant of Escherichia coli.

The Lactococcus lactis adhE gene, which encodes a multifunctional alcohol dehydrogenase, has been cloned and characterized. A DNA fragment encoding the putative alcohol dehydrogenase domain of the AdhE protein was cloned by screening an L. lactis genomic library in a fermentative mutant of Escherichia coli and selecting for the ability to grow anaerobically. Further analysis of the clone obtained allowed the cloning of the entire adhE gene sequence. Analysis of adhE expression in L. lactis during anaerobiosis showed induction at the transcriptional level, especially in medium containing glucose. Constructed mutant strains produced reduced amounts of ethanol under anaerobic conditions. With the L. lactis gene as a probe, adhE homologs were found in other industrially relevant lactic acid bacteria.

Alcohol Dehydrogenase↗

PubMed1997

[The long-term prognosis of patients with acute chest pain of various origins].

A total of 204 patients with acute chest pain, but without myocardial infarction (non-AMI) were included. In 56 a definite diagnosis was obtained within 24-48 hours of admission. The remaining 148 patients underwent a comprehensive examination program. Ischaemic heart disease (IHD) was diagnosed in 64 patients, 81 had gastro-oesophageal disorders, 58 chest wall disorders, nine pericarditis, five pulmonary embolism, four pneumonia/pleuritis, three pulmonary cancer, two dissecting aortic aneurysm, one aortic stenosis and one herpes zoster. During 33 months of follow-up, 31 of the 64 patients with IHD had a cardiac event (cardiac deaths, non-fatal AMI, bypass surgery or PTCA) whereas only three events occurred among the 140 patients without IHD (p < 0.00001). However, the frequency of readmissions and of recurrent episodes of chest pain were similar in the three major diagnostic groups (NS). It is concluded that the high risk subset of a non-AMI population can be identified by means of non-invasive cardiac examination. The remainder who have other diagnoses are at low risk. However, the morbidity is high with frequent readmissions and recurrent episodes of chest pain, and the need for development of strategies with regard to diagnosis and treatment of these patients is emphasized.

Acute Disease↗

PubMed1997

Cloning, expression, and characterization of the Lactococcus lactis pfl gene, encoding pyruvate formate-lyase.

The Lactococcus lactis pfl gene, encoding pyruvate formate-lyase (PFL), has been cloned and characterized. The deduced amino acid sequence of the L. lactis PFL. protein showed high similarity to those of other bacterial PFL proteins and included the conserved glycine residue involved in posttranslational activation of PFL. The genetic organization of the chromosomal pfl region in L. lactis showed differences from other characterized pfl loci, with an upstream open reading frame independently transcribed in the same orientation as the pfl gene. The gene coding for PFL-activase (act), normally found downstream of pfl, was not identified in L. lactis. Analysis of pfl expression showed a strong induction under anaerobiosis at the transcriptional level independent of the growth medium used. During growth with galactose, pfl showed the highest levels of expression. Constructed L. lactis pfl strains were unable to produce formate under anaerobic growth. Higher levels of diacetyl and acetoin were produced anaerobically in the constructed Lactococcus lactis subsp. lactis biovar diacetylactis pfl strain.

Acetyltransferases↗

PubMed1996

The diagnoses of patients admitted with acute chest pain but without myocardial infarction.

OBJECTIVE: The purpose of this study was to describe the frequencies of various diagnoses in patients admitted with acute chest pain, but without acute myocardial infarction, and to evaluate a non-invasive screening programme for these patients. PATIENTS: A total of 204 consecutive non-acute myocardial infarction patients were included. Fifty-six had a definite diagnosis within 48 h, whereas 148 patients underwent an examination programme including pulmonary scintigraphy, echocardiography, exercise electrocardiography, myocardial scintigraphy, Holter monitoring, hyperventilation test, oesophago-gastro-duodenoscopy, 3 h monitoring of oesophageal pH, oesophageal manometry, Bernstein test, physical examination of the chest wall and thoracic spine, bronchial histamine provocation test and ultrasonic examination of the abdomen. RESULTS: According to predefined criteria, 186 patients (91%) had at least one diagnosis, 144 had one, whereas 39 had two, and three patients had three diagnoses. In 18 patients no diagnosis was obtained. The diagnoses belonged mainly to three groups: (1) ischaemic heart disease (n = 64); (2) gastro-oesophageal diseases (n = 85); (3) chest-wall syndromes (n = 58). Less frequent diagnoses included pulmonary embolism, pleuritis/pneumonia, lung cancer, aortic stenosis, aortic aneurysm and herpes zoster. CONCLUSIONS: The high risk subset of a non-acute myocardial infarction population can be identified by means of a clinical evaluation and non-invasive cardiac examinations. Among the remainder, pulmonary embolism, gastro-oesophageal diseases and chest-wall syndromes should be paid special attention. A careful physical examination of the chest wall and upper endoscopy seems to be the most cost-beneficial examination to employ in this subset.

Acute Disease↗

PubMed1996

Effect of pre- and post-heat shock temperature on the persistence of thermotolerance and heat shock-induced proteins in Listeria monocytogenes.

The effect of incubation temperature, before and after a heat shock, on thermotolerance of Listeria monocytogenes at 58 degrees C was investigated. Exposing cells grown at 10 degrees C and 30 degrees C to a heat shock resulted in similar rises in thermotolerance while the increase was significantly higher when cells were grown at 4 degrees C prior to the heat shock. Cells held at 4 degrees C and 10 degrees C after heat shock maintained heat shock-induced thermotolerance for longer than cells held at 30 degrees C. The growth temperature prior to inactivation had negligible effect on the persistence of heat shock-induced thermotolerance. Concurrent with measurements of thermotolerance were measurements of the levels of heat shock-induced proteins. Major proteins showing increased synthesis upon the heat shock had approximate molecular weights of 84, 74, 63, 25 and 19 kDa. There was little correlation between the loss of thermotolerance after the heat shock and the levels of these proteins. Thermotolerance of heat shocked and non-heat shocked cells was described by traditional log-linear kinetics and a model describing a sigmoidal death curve (logistic model). Employing log-linear kinetics resulted in a poor fit to a major part of the data whereas a good fit was achieved by the use of a logistic model.

Bacterial Proteins↗

PubMed1995

Ca selectivity of the transduction channels in the hair cells of the frog sacculus.

The extracellular receptor currents evoked by step displacements of the otolithic membrane of the isolated saccular macula of Rana esculenta were recorded under transepithelial voltage clamp conditions. With the aim to depolarize the hair cells and increase the fractional resistance of the apical membranes, the basal side of the preparation was bathed in saline with an increased K+ concentration (62 mM). This caused a shift in the non-linear receptor current-voltage relation along the voltage axis of -51 mV +/- 10 mV; (mean +/- SD; n = 32) and a reduction in the transepithelial resistance of 10%. Under these conditions the electrical properties of the macula are assumed to be controlled by the apical membranes. The effects of different concentrations of Ca2+ in the apical solution on the receptor current-voltage relation were examined. Change of the apical Ca2+ concentration (range 3 mM to 70 microM) varied the transepithelial voltage at which the receptor current was zero (Vrev). Fitting a modified constant field equation to the relation between the apical Ca2+ concentration and the change in Vrev gave an estimate of PCa/PK of the transduction channels of 212. Furthermore, a high relative permeability of the transduction channels for other divalent cations (Ba2+, Sr2+) was measured, whereas Mn2+ inhibited the receptor current. The receptor current was inhibited by amiloride (IC50 3.2 microM +/- 1.7 microM) and nifedipine (IC50 1.9 microM +/- 0.6 microM). Reduction of the apical Ca2+ concentration to 90 microM in standard apical solution reduced the size of the receptor current to 67% +/- 30% (n = 17) compared to control but did not affect the shape of the receptor current-voltage relation. Subsequent substitution of K+ by Na+ caused a further reduction of the receptor current to 32% +/- 29% (n = 9), changed the receptor current-voltage relation into a linear relation and diminished the adaptation of the receptor current. These results indicate that the mechano-electrical transduction channels of the frog saccular hair cells are highly selective to Ca2+ and that the conductance of the channels may be influenced by the apical monovalent cation species.

Animals↗

PubMed1994

The concentration of polypeptide chain release factors 1 and 2 at different growth rates of Escherichia coli.

The number of molecules of release factor-1 (RF-1) and release factor-2 (RF-2) per Escherichia coli cell grown at various rates was determined using quantitative Western blotting of total solubilized cell protein. The number of RF-1 molecules per cell increased from 1200 to 4900, and of RF-2 from 5900 to 24,900 as growth rates increased from 0.3 to 2.4 doublings per hour. The cellular concentration of the release factors, and therefore efficient termination of protein synthesis is maintained by the increased expression of both RFs as growth rate increases. The expression of both release factors RF-1 and RF-2 is co-ordinated with that of the rest of the translational apparatus, although the increases are less for RF than that for the ribosomes under the same conditions. A significant proportion of the RF pool was found associated with the ribosome fraction. The percentage of ribosomes containing an RF molecule increased from 21 to 33% as the translational rate increased over the growth rate range. Since the cellular concentration of the release factors and their specific activity does not vary significantly with growth rate, this can not provide for an increase in the rate at any of the steps of termination. The postulated strong stop signals, UAAU and UAAG, in genes that are highly expressed at fast growth rates, may result in an increase in the termination rate as a consequence of increased efficiency of decoding by RFs.

Cell Fractionation↗

PubMed1994

Local cooling prolongs oesophageal transit in humans.

The influence of local cooling on oesophageal transit was studied in eight healthy volunteers by oesophageal radionuclide transit. Compared with lukewarm (18 degrees C) water a significantly prolonged mean transit time (MTT) was found after ingestion of cold liquid (4 degrees C) and a slightly shorter MTT with 50 degrees C. The effect was of short duration lasting less than 2 min. The effect of atropine, morphine and naloxone, on the influence of local cooling was evaluated. Morphine (7 x 5 mg i.v.) abolished the effect of cooling on MTT. Naloxone (1 x 6 mg i.v.) reduced the effect of cooling, but the difference between 4 degrees C and 19 degrees C was significant still. Atropine (1 mg i.v.) had no effect on the increase in MTT at 4 degrees C. It is concluded that in humans local cooling increases oesophageal MTT. Local warming shortened MTT slightly. The abolishment of the influence of cooling by morphine suggests that opioids may be involved.

Adult↗

PubMed1994

Ionic selectivity of the mechano-electrical transduction channels in the hair cells of the frog sacculus.

In the isolated saccular macula of Rana esculenta extracellular hair cell receptor currents evoked by mechanical stimulation of the otolithic membrane were recorded under transepithelial voltage clamp conditions. The ionic selectivity of the mechano-electrical transduction channels of the hair cells was determined by examining the effects of different concentrations of Ca2+ and K+ in the apical solution on the transepithelial voltage at which the extracellular receptor current was zero (Vrev). Changing the concentration of Ca2+ from 0.26 mM to 0.026 and to 2.6 mM at a constant K+ concentration caused changes in Vrev of -15 +/- 7 mV (mean +/- SD; n = 9) and 20 +/- 6 mV (n = 13), respectively. The relative ionic permeabilities of the transduction channels were estimated from a modified Goldman, Hodgkin and Katz equation, assuming that 80% of the transepithelial resistance is located in the apical membranes of the hair cells. The permeability of the transduction channels for Ca2+ was found to be two orders of magnitude larger than that for K+. The measured effects on Vrev of changing the concentration of K+ at constant ionic strength and at different constant Ca2+ concentrations were well predicted by the same equation. These results indicate that the transduction channels of the frog saccular hair cells are highly selective to Ca2+.

Acoustic Maculae↗

PubMed1994

Prevention of recurrent acute otitis media in otitis-prone children by intermittent prophylaxis with penicillin.

The question whether penicillin V (pcV) given intermittently upon signs of upper respiratory tract infections (URTI) in otitis-prone children might prevent recurrent bouts of acute purulent otitis media (AOM) is addressed. As compared with continuous long-term antibiotic treatment as prophylaxis in otitis-prone children, intermittent administration would reduce the overall consumption of antibiotics. Seventy-six otitis-prone children less than 18 months of age were included in this double-blind, randomized, placebo-controlled multicentre study. Follow-up was from January till June. One hundred and twenty-three episodes of AOM occurred. The number of AOM episodes was reduced by 50% in the children on pcV during URTI episodes as compared with those on placebo. No obvious ecological drawbacks were noted. Thus, the described mode of pcV administration seems to be a rational and safe way to reduce the number of AOM episodes in otitis-prone children.

Acute Disease↗

PubMed1994

The first fatal case of Vibrio vulnificus infection in Denmark.

Vibrio vulnificus can cause severe infections in humans and persons with preexisting liver disorders are especially at risk. In this paper we report what is to our knowledge the first fatal case of V. vulnificus infection in Denmark. The patient was a 68-year-old man with a history of chronic lymphatic leukemia and hepatic cirrhosis. Physicians should be aware of the clinical manifestations of this disease and should be especially attentive to patients at risk of acquiring the infection if there has been possible exposure to V. vulnificus by contact with seawater or contaminated material such as eels.

Aged↗

PubMed1993

Release factor-dependent false stops are infrequent in Escherichia coli.

We have estimated the frequency of release factor dependent events in which a sense codon is mistakenly translated as a stop codon. We refer to this event as a "false stop". In order to facilitate the measurement of false stop freqeuncies we have used a plasmid expression system to increase individually the cellular levels of release factor (RF) I a and of release factor (RF) 2. We were then able to measure the loss of translational processivity with the aid of a lacZ processivity assay at different concentrations of the release factors. We find that a 30- to 40-fold increase of the RF1 concentration reduces lacZ processivity from 0.6 to 0.3. Assuming that the processivity loss is due only to false stops and that the RF1 overproduction data can be extrapolated back linearly to the normal RF1 concentration in the cell, this corresponds to a false stop frequency close to 10(-5) per codon in the presence of normal amounts of RF1. Furthermore, a threefold increase of the RF2 concentrations had no measurable effect on the processivity of the lacZ gene. Our data suggest that false stops are relatively infrequent compared to the incidence of other translation errors.

Cloning, Molecular↗