The mutator gene swi8 effects specific mutations in the mating-type region of Schizosaccharomyces pombe

The swi8+ gene of Schizosaccharomyces pombe appears to be involved in the termination step of copy synthesis during mating-type (MT) switching. Mutations in swi8 confer a general mutator phenotype and, in particular, generate specific mutations in the MT region. Sequencing of the MT cassettes of the h90 swi8-137 mutant revealed three altered sites. One is situated at the switching (smt) signal adjacent to the H1 homology box of the expression locus mat1:1. It reduces the rate of MT switching. The alteration at the smt signal arose frequently in other h90 swi8 strains and is probably caused by gene conversion in which the sequence adjacent to the H1 box of mat2:2 is used as template. This change might be generated during the process of MT switching when hybrid DNA formation is anomalously extended into the more heterologous region flanking the H1 homology box. In addition to the gene conversion at mat1:1, two mutations were found in the H3 homology boxes of the silent cassettes mat2:2 and mat3:3.

Nucleotide sequence analysis of enteropathogenic Escherichia coli (EPEC) adherence factor probe and development of PCR for rapid detection of EPEC harboring virulence plasmids

The 1-kb BamHI-SalI fragment from plasmid pMAR2 termed the enteropathogenic Escherichia coli (EPEC) adherence factor (EAF) probe was cloned in pUC19 and pK18. The nucleotide sequence of this fragment was determined, and a set of primers was designed to amplify a 397-bp region associated with pMAR2 by PCR. An analysis of the whole EAF sequence with database libraries indicated no significant homology to any known genes. However, between bases 701 and 787 of the fragment, an 82.8% homology between the EAF and the insertion sequence IS630 of Shigella sonnei exists. The results of PCR with primers of the EAF sequence demonstrated that all of the 151 EAF probe-positive EPEC strains with localized adherence to HEp-2 cells yielded positive EAF PCR results. In contrast, none of the 277 EAF probe-negative strains reacted to the EAF PCR. In addition, the PCR assay was successfully used to generate vector-free digoxigenin-labeled EAF fragments that gave valid results in colony blot hybridization assays. The EAF PCR appears to be a specific and efficient method for the detection of EPEC strains carrying the EAF plasmids.

Purification and PCR-based cDNA cloning of a plastidial n-6 desaturase

A plastidial membrane-bound n-6 desaturase from spinach (Spinacia oleracea) was purified from chloroplast envelope membranes by anion exchange, cation exchange and ferredoxin-affinity chromatography. The molecular mass of the protein was estimated by SDS-PAGE to be 40 kDa. The highest specific activity of the desaturase in the final preparation was 196 nmol/min per mg protein with free oleic acid as the substrate. The N-terminal amino acid sequence of the blotted protein was determined and used for the construction of a degenerated and inosine-containing oligonucleotide primer for PCR experiments with cDNA transcribed from leaf mRNA. A 3'-RACE experiment with this primer amplified a single band of 1500 bp that after sequencing showed an open reading frame of 382 amino acids corresponding to a protein of 43 kDa. The 5' end of the cDNA was amplified by a 5'-RACE experiment and isolated as a 500 bp fragment. Sequencing of this DNA revealed an additional 65 amino acids at the N-terminus of the native protein that are attributed to a plastidial leader peptide. With appropriate primers derived from these sequences a full-length clone was amplified by PCR and sequenced. Comparison of the plastidial oleate desaturase with the homologous enzyme from cyanobacteria showed about 50% amino acid homology. Comparison with other desaturases revealed three histidine boxes with the general sequence HXXXH that are highly conserved in all membrane-bound desaturases. These boxes might be involved in metal ion complexation required for reduction of oxygen.

[Diagnosis of urinary tract infections in puerperium]

Urinary tract infections (UTI) are the most frequent nosocomial infections of women during puerperium. Since, in these women, diagnostic accuracy is affected by lochial secretion, suprapubic urinary bladder puncture (SPB) is recommended. Between December 1989 and January 1993, we subjected 903 women to suprapubic urinary bladder puncture (SpBP) at the 4th or 5th day after delivery. A urine culture of SpBP was done in all cases. Semiquantitative leukocyte counts (n = 891) and nitrite test (n = 830) were done on mid-stream urine (MSU). Side by side with microbiological investigation for urinary tract pathogens via SpPB, MSU was performed in 246 cases immediately after SpPB had been carried out. Leukocyte counts were also estimated in SpBP urine samples. In 370 (41.1%) of 903 SpBP, one or more microorganisms were cultivated. Only 36 (4.0%) of 903 women showed UTI symptoms. Microorganisms were detectable via SpBP in only 26 (72.7%) of these 36 symptomatic patients. Vaginal-operative or secondary caesarean section are related to an increased UTI rate (p < 0.001). UTI were also significantly (p < 0.0001) more frequent in women subjected to catheterisation sub partu (54.5%) compared to no catheterism (24.4%). No significant differences between the number of leukocytes in MSU sediment and the SpBP findings were seen. Semiquantitative leukocyte counts in SpBP offered a significantly (p < 0.001) increased number of leukocytes in cases with microorganism detection in SpBP irrespective of MSU findings. These results justify the designation of uterine tract infection also in the absence of complaints as "infection" and not common "bacteriuria".(ABSTRACT TRUNCATED AT 250 WORDS)

Demonstration of Borrelia burgdorferi DNA in urine samples from healthy humans whose sera contain B. burgdorferi-specific antibodies

Since the possibility of asymptomatic infection with Borrelia burgdorferi has been suggested by a positive serology found in healthy subjects, we hypothesized that these subjects might excrete borrelial DNA sequences in urine as happens in patients with Lyme borreliosis. We found borrelial sequences by nested PCR in the urine samples from 3 of 13 healthy B. burgdorferi antibody-positive adults but not in urine samples from 79 antibody-negative healthy controls. After therapy with doxycycline, the urine samples were repeatedly negative for B. burgdorferi DNA. We conclude that urinary excretion of borrelial DNA sequences may occur in seropositive healthy subjects during asymptomatic infection. Demonstration of such sequences in urine must be interpreted cautiously and may not necessarily prove a borrelial cause of disease.

Cytomegalovirus in liver biopsies of marrow transplant recipients: detection methods, clinical, histological and immunohistological features

In a retrospective analysis liver biopsy specimens obtained from 44 marrow transplant recipients were studied to evaluate the frequency of local presence of human cytomegalovirus (CMV) and graft-versus-host disease (GvHD)-like histological and immunohistological alterations in patients with and without liver dysfunction following bone marrow transplantation (BMT). In 22 of 28 patients with marked liver dysfunction after BMT and histopathological alterations described as typical for acute GvHD CMV could be detected in the liver biopsy specimen. The polymerase chain reaction (PCR) technique revealed the highest sensitivity for CMV detection in liver biopsy samples, but in 20 of 22 PCR-positive specimens CMV infection could be confirmed by at least one additional technique. All the liver biopsies obtained from 16 patients with normal liver function lacking histopathological signs of GvHD were CMV negative. In all 3 patients with CMV-positive liver biopsy started on antiviral therapy liver function improved and no generalized CMV disease occurred. All the 4 patients without local presence of CMV started on severe immunosuppressive therapy showed an improvement of liver dysfunction without occurrence of CMV infection. Local CMV infection of the liver could not be differentiated from hepatic GvHD by clinical and histopathological features, nor by immunohistological analysis of the bile duct epithelium. In contrast, only in liver biopsy with local viral presence could an increase in HLA class II- and ICAM-1 expression be demonstrated on hepatocytes. Thus, especially the high negative predictive value of the PCR technique helps to manage the patient with liver dysfunction after BMT.

The mating-type region of Schizosaccharomyces pombe contains an essential gene encoding a protein homologous to human modulators of HIV transactivation

In Schizosaccharomyces pombe, an intrachromosomal crossover between the mating type (MT) expression locus and one of the silent donor cassettes is lethal due to the loss of the intervening L region. The region contains one essential gene, let1. This gene was cloned and sequenced. The deduced amino acid (aa) sequence of let1 shows extensive homologies with SUG1 from Saccharomyces cerevisiae. Significant homologies were also found with the human HIV transactivation modulators, MSS1 and TBP-1, as well as with subunit 4 of the mammalian 26 S protease. The data indicate that let1 is a member of a recently defined multigene family of ATPases.

Development of granulomas and vascular fibrocellular proliferation in the lungs of pigs receiving long-term lipid-based parenteral nutrition

The lungs of pigs receiving long-term total parenteral nutrition (TPN) have been studied. A total of 20 pigs were tentatively infused with TPN through central venous catheters for 7 weeks. To secure adequate nutrition and gastrointestinal absorbance of nutrients, an additional full oral diet was given to eight of these animals. Fifteen control animals received Ringer solution through central venous catheters in addition to the oral diet. All animals infused with TPN for 7 weeks developed lung granulomas, a finding not observed in control animals. No lung granulomas were seen in three TPN animals sacrificed after 3 to 5 weeks owing to illness. All TPN animals also developed tissue reactions suggesting long-standing lung vascular inflammation. Similar vascular changes were seen in seven control animals that had bacterial infection or endotoxemia. The total amount of neutral fat in lung homogenate tended to increase in animals given TPN, and the linoleic acid content was significantly increased. In conclusion, long-term TPN caused lung granulomas in pigs. Vascular damage seemed to be accelerated by bacterial infection as well as by the TPN. The tissue reactions presumably involved long-term activation of monocytes/macrophages.

Porphyrinogenic effects of atracurium, vecuronium, and pancuronium in a primed rat model

Steroidal muscle relaxants might theoretically be contraindicated in acute hepatic porphyrias. Atracurium, on the other hand, has been proposed as the muscle relaxant of choice because of its extrahepatic degradation. To further investigate this problem, equipotent doses of atracurium, vecuronium, and pancuronium were determined in male Sprague Dawley rats, using evoked electromyography. After this pilot study, 64 rats were anesthetized, mechanically ventilated, and randomly allocated to eight groups. Animals in groups 1 through 4 received an intraperitoneal injection of arachis-oil 20 h before the experiments. For groups 5 through 8, an experimental porphyria was induced by use of the chemical substance 3,5-dicarbethoxy-1,4-dihydrocollidine (DDC), which was dissolved in arachis-oil and given 20 h prior to the beginning of the study. Rats of groups 1 and 5 served as controls; they received saline and were not given muscle relaxants throughout the experiment. For groups 2 and 6, atracurium was administered at a dosage of 4 mg/kg of body weight, followed by a continuous infusion of 15 mg/kg/h. Animals of groups 3 and 7 received vecuronium at a dosage of 1.5 mg/kg, followed by 7.5 mg/kg/h. For groups 4 and 8, pancuronium was given (0.75 mg/kg and 2.5 mg/kg/h, respectively). At the end of the 3-h study period, the liver was perfused and excised, and urine was obtained. Activity of the hepatic enzyme delta-aminolevulinic acid synthase (ALAS) and urinary concentrations of delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of attaching and effacing Escherichia coli in stool samples from patients and controls

Enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) have the ability to cause 'attaching and effacing' (AE) lesions; the genes necessary to cause AE in both of these pathogroups have been identified and termed eae. Using colony hybridization, we screened 237 stool samples from patients with diarrhea, and 237 stool samples from age-matched controls for the presence of E. coli carrying eae. Individual colonies harbouring eae could be recovered from 7 (2.9%) of the patient stools, as well as from 6 (2.5%) of the control stools. All these E. coli isolates were positive in the fluorescence actin staining (FAS) test. In addition, all the samples were also probed for Shiga-like toxin (slt) genes and the EPEC adherence factor (EAF) to evaluate whether testing for eae identified all EHEC and class I EPEC. Of the 7 patient samples harbouring E. coli with eae, 4 had E. coli with eae and slt genes, and 2 had E. coli with eae and EAF sequences. In 2 of the 237 patient stools, E. coli which were eae and EAF negative but slt probe positive could be recovered. These 2 E. coli strains were non-reactive in the FAS test. Of the control samples, none of the E. coli strains, including the 6 samples containing eae positive strains, possessed EAF or slt-sequences. In concrete terms, the similar eae incidence found in both E. coli isolates from patients and controls is currently of limited clinical diagnostic value and more importantly, the eae probe could not identify all slt-harbouring E. coli. On the basis of these results, the use of the eae-probe cannot be recommended in preference to the slt probes for the detection of EHEC.

Helicobacter pylori infection and serum pepsinogen A, pepsinogen C, and gastrin in gastritis and peptic ulcer: significance of inflammation and effect of bacterial eradication

OBJECTIVES

To study the relationship between Helicobacter pylori infection, gastric inflammatory scores, and fasting gastrin and pepsinogen A and C concentrations, and to evaluate the effect of treatment on these parameters.

METHODS

Gastrin and pepsinogen A and C concentrations were measured in 36 patients with gastritis, 10 gastric ulcer patients, 12 duodenal ulcer patients, and in 15 subjects with normal gastric mucosa, by standard radioimmunoassay techniques. Fifteen patients with H. pylori infection underwent triple therapy (bismuth subsalicylate, amoxicillin, metronidazole) and were reassessed 1 month later.

RESULTS

Fasting gastrin and pepsinogen A and C concentrations were significantly higher in H. pylori-positive gastritis and peptic ulcer patients than in subjects with normal mucosa and in patients with H. pylori-negative gastritis. There was a significant correlation between inflammatory scores and serum gastrin (r = 0.45, p < 0.0001), and pepsinogen A (r = 0.33, p < 0.006) and pepsinogen C (r = 0.55, p < 0.0001) concentrations. Neither sex nor age affected basal gastrin and pepsinogen concentrations. Eradication of H. pylori infection was successful in 12 patients and resulted in a significant fall in serum gastrin and in pepsinogen A and C concentrations, and in a concomitant improvement of the inflammatory scores. Serum peptide levels and gastritis scores were unchanged in those patients in whom H. pylori infection persisted.

CONCLUSIONS

These findings suggest that hypergastrinemia and hyperpepsinogenemia are secondary to H. pylori infection and are related to mucosal inflammation.

Fragrance administration to reduce anxiety during MR imaging

Fifty-seven outpatients received either heliotropin (a vanillalike scent) with humidified air (n = 20) or humidified air alone (n = 37) via a nasal cannula during magnetic resonance imaging in the diagnostic workup for cancer. Delivery of heliotropin and air was determined by a computer-controlled schedule. Fragrance administration resulted in a statistically significant reduction in average overall patient-rated anxiety (on a visual analog scale) during imaging in patients who found the fragrance moderately to extremely pleasant. Administration of fragrance was associated with 63% less anxiety than administration of humidified air alone. Physiologic measures (pulse and heart rate) did not show a statistically significant effect with fragrance administration.

Polymerase chain reaction for the identification of Porphyromonas gingivalis collagenase genes

Porphyromonas gingivalis has been shown to exhibit genetic diversity possibly resulting in variation of virulence. In the present study a potential virulence factor was targeted for the detection of P. gingivalis. A 548 bp fragment of the collagenase gene (prtC) from Porphyromonas gingivalis ATCC 33277 was amplified by polymerase chain reaction (PCR) using oligonucleotides derived from the middle portion of prtC. From 16 of 21 clinical P. gingivalis strains, a PCR product of similar size to the prtC could be obtained. These 16 P. gingivalis strains were confirmed as positive for prtC using DNA hybridization with a digoxigenin-labeled prtC PCR product as a probe. In 12 of the 16 prtC positive strains, the restriction analysis of the PCR products revealed fragment patterns identical to the known sequence. In the other 4 prtC positive strains, 4 distinct patterns were found. Of these strains, nucleotide sequence analysis of a 400 bp PCR product stretch revealed 79.1%, 83.0%, 84.8 and 89.5% homology with the known nucleotide sequence for this specific region. Sequence analysis of the PCR products from the ATCC 33277 strain demonstrated 93.7% homology. The limit of detection for the PCR was about 100 organisms. None of the other 48 tested strains of 16 bacterial species derived from oral and extraoral infections yielded a PCR product. The PCR was also used for the detection of prtC sequences in dental plaque. Our data indicate that not all P. gingivalis strains have prtC. Nucleotide heterogeneity exists among P. gingivalis with prtC.(ABSTRACT TRUNCATED AT 250 WORDS)

[The corroborative capacity and value of imaging diagnosis and duplex sonography in newborn infants with necrotizing enterocolitis]

In this prospective study 101 sonographic examinations of superior mesenteric artery blood flow velocities, indices and blood flow volume were consecutively performed in 41 newborn to diagnose necrotising enterocolitis (NEC). Intramural and portal venous gas was also estimated. The artifacts of air in the AMS and the portal system were examined in an experimental study. The results of sonography and abdominal radiography were equivalent in the case of definitely established NEC, portal venous gas being more sensitive to detection by sonography. Abdominal radiography was indicated as the primary examination in case of a clearly identified clinical course. Sonography should be performed so that fewer radiographs will be required in the following course of disease.

Switching gene swi6, involved in repression of silent mating-type loci in fission yeast, encodes a homologue of chromatin-associated proteins from Drosophila and mammals

The switching gene swi6 of Schizosaccharomyces pombe is involved in the repression of the silent mating-type loci mat2 and mat3. We have cloned the gene by functional complementation of the switching defect of the swi6-115 mutation. DNA sequence analyses revealed an open reading frame of 984 bp coding for a putative protein of 328 amino acids (aa). The isolation of a swi6 cDNA confirmed this result. Gene replacement showed that swi6 is not essential for viability. The Swi6 protein is very hydrophilic; it contains 41% charged aa. A region of 48 aa is homologous to a sequence motif found in the chromatin-associated proteins, HP1 and Polycomb (Drosophila melanogaster), M31, M32 and M33 (mouse), and the human HSM1 protein. This motif is called chromo domain (chromatin organization modifier). Our results indicate that Swi6 is a structural component of chromatin. Swi6 may have the function to compact mat2 and mat3 into a heterochromatin-like conformation which represses the transcription of these silent cassettes.

Highly conserved B-subunit genes of Shiga-like toxin II variants found in Escherichia coli O157 strains

To determine the degree of heterogeneity among Shiga-like toxin-II (SLT-II)-related toxins present in enterohemorrhagic Escherichia coli O157 strains, slt-IIB-related genes of 15 strains were amplified and sequenced. Of these 15 isolates, six contained only the slt-II-related genes, seven strains harbored slt-II-related genes together with slt-II, and two strains had slt-II-related genes plus slt-I. In strains carrying slt-II-related genes alone or in combination with slt-I, the PCR fragments were directly subjected to Taq cycle sequence analysis. Direct sequencing was not possible with the seven strains possessing both slt-II and slt-II-related genes, since the PCR products contained both genes. In order to allow sequence analysis of these slt-II-related genes, the PCR products were first subjected to restriction enzyme digestion with FokI, which selectively digested slt-IIB. This resulted in an undigested 270-bp fragment consisting of pure slt-II-related genes. Interestingly, comparison of the nucleotide sequences revealed 100% homology of all analyzed 15 slt-IIB-related toxin genes. In addition, the nucleotide sequence of slt-IIB-related toxin genes were identical to slt-IIcB. Our findings indicate that SLT-IIc is a major variant form of SLT-II present in E. coli O157 strains.