Respiratory virus infections in decedents in a large, urban medical examiner's office

OBJECTIVE

Most respiratory virus surveillance relies on medically attended respiratory illness, but an understanding of the true patterns of infection independent of care-seeking behaviour would enhance clinical and public health responses to respiratory virus outbreaks. We evaluated the potential of decedent surveillance by estimating the burden of respiratory virus infection in decedents in a large, urban medical examiner's office.

STUDY DESIGN

Observational.

METHODS

In 2020-2022, we tested nasopharyngeal swabs from 4121 decedents in Detroit, Michigan for 15 respiratory viruses, including SARS-CoV-2, respiratory syncytial virus, and influenza virus A and B. We analysed infection prevalence over time and by age, sex, race/ethnicity, and manner of death.

RESULTS

Of 4113 valid tests, 30.2% were positive for at least one virus, and 6.1% were positive for multiple viruses. All viruses were detected except for influenza A/H1N1 and influenza B. The most prevalent viruses were SARS-CoV-2 (15.7%), rhinovirus (11.2%), and adenovirus (4.9%), which were detected in all months. Most viruses exhibited decreasing prevalence with age, higher prevalence among Black and Hispanic than among White decedents and lower prevalence among deaths from natural causes; SARS-CoV-2 was a notable exception to the patterns by age and manner of death, instead reflecting community trends in catchment counties.

CONCLUSIONS

There was high prevalence and diversity of respiratory viruses in decedents entering a large, urban medical examiner's office. Decedent surveillance could offer a clearer picture of the true underlying burden of infection, motivating public health priorities for intervention and vaccine development, and augmenting data for real-time response to respiratory virus outbreaks.

Secondary reconstruction of the orbit and conjunctival sac - a case report

The authors present a novel modification of vastus lateralis muscle free flap based orbital reconstruction in a 41-year-old patient, with a secondary defect to an injury with technical oil under high pressure. The patient underwent multiple reconstructive procedures in different medical centers with poor functional and esthetic results including simple local plasty techniques. The patient underwent simultaneous reconstruction of the soft tissues of the orbit, and conjunctival sac based on a prelaminated vastus lateralis free flap. The two-stage reconstruction of these structures is beneficial both for the patient's psychical and mental condition and for health system finances. Therefore, whenever it's possible, we should try to decrease the number of required procedures. The authors believe that their technique can significantly improve the quality of life of patients after exenteration but simultaneously they emphasize the need to carry out more procedures in order to refine it.

Hexahydroxytriphenylene for the synthesis of group 13 MOFs - a new inorganic building unit in a β-cristobalite type structure

Two new, microporous MOFs of framework composition ((CH3)2NH2)2[M3O(HHTP)(HHTP˙)], M = Al3+, Ga3+, H6HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene, are described. Electron diffraction combined with molecular simulations show that these compounds crystallize in the β-cristobalite structure, containing a new type of trinuclear inorganic building unit for MOFs and radical anions.

Diet and feeding niches of juvenile Gadus morhua, Melanogrammus aeglefinus and Merlangius merlangus during the settlement transition in the northern North Sea

A study on the feeding ecology of juvenile cod Gadus morhua, haddock Melanogrammus aeglefinus and whiting Merlangius merlangus during the pelagic to demersal transition was carried out on fishes sampled throughout their settlement season at a local nursery ground in the north-western North Sea, off the Scottish east coast. A comprehensive quantitative taxonomic analysis of the diets, as described in the paper, showed the emergence of distinctive feeding niches, minimizing the potential for competition between species and size categories. The diet of the juveniles changed with fish size, water depth, time of year and distance offshore. Small G. morhua were present in the study area earlier in the season, settled further inshore and ate a higher proportion of pelagic prey (copepods) and as size increased they moved into deeper waters and targeted larger, more benthic prey. As M. aeglefinus grew larger and moved into deeper waters, a diet of largely copepods, amphipods, pelagic Ammodytes spp., cyprids and pelagic gastropods evolved to one dominated predominantly by fishes and benthic invertebrates. In the case of M. merlangus, widespread ages and sizes throughout the sampling season, a consequence of their more protracted spawning season, resulted in dietary changes which were more likely to be influenced by seasonal changes in the prey field, in addition to developmental (size) changes, than the diets of the other two species.

Pleural fluid adenosine deaminase and interferon gamma as diagnostic tools in tuberculosis pleurisy

Several biological markers have been proposed to improve the efficacy of diagnosing tuberculous pleurisy. The study was undertaken to evaluate the accuracy of pleural fluid adenosine deaminase (ADA) activity and interferon-gamma (IFN-gamma) concentration in differentiating tuberculous pleural effusion (TPE) and nontuberculous pleural effusion (non-TPE). Ninety four patients (50 M and 44 F, mean age 60+/-18, range 18-95 years) with pleural effusion (PE) were studied. TPE was diagnosed in patients with: (i) positive pleural fluid or pleural biopsy culture or (ii) granulomas in the pleural biopsy specimen, after exclusion of other granulomatous diseases. Pleural fluid ADA activity was measured with the colorimetric method of Giusti, while IFN-gamma level was measured with ELISA. TPE was diagnosed in 28 patients. The non-TPE group consisted of 35 patients with malignant PE, 20 patients with parapneumonic effusion/pleural empyema, 5 with pleural transudate, and 6 with miscellaneous PE. The ADA activity and IFN-gamma concentration were significantly higher in TPE than in non-TPE (614.1+/-324.5 vs. 15.1+/-36.0 pg/ml, P<0.0001 and 75.1+/-39.1 vs. 11.0+/-16.6 U/l respectively, P<0.0001). The diagnostic sensitivity and specificity of IFN-gamma measurement (cut-off value of 75.0 pg/ml) were 100% and 98.5% respectively and were similar to those of ADA (100% and 93.9% at the cut-off value of 40.3 U/L). We conclude that pleural fluid ADA activity and IFN-gamma concentration are highly sensitive and specific markers of tuberculous pleurisy.

Pancreatic secretion differs according to the genotype of growing pigs

The objective of this study was to investigate the secretion of pancreatic enzymes and antibacterial activity in weaned pigs of three pure breeds, Pietrain, Duroc and Polish synthetic line 990, to look for eventual differences related to the genotype. Six male pigs of each breed, about 24 kg mean body weight, were equipped with chronic pancreatic duct catheters and duodenal cannulas to assess pure pancreatic juice, and jugular vein catheters for blood withdrawal. Pancreatic juice was collected before and after the morning feeding. Protein output and enzyme activities revealed two distinct profiles: strong manifestation of the prandial phase in Pietrain and line 990 pigs, and weak manifestation in Duroc. The antibacterial activity did not follow the enzyme kinetics, and it was the strongest in pancreatic juice from Pietrain pigs. Postprandial insulinaemia was reduced in the order of: line 990>Pietrain>Duroc. A slight (not significant) tendency towards a reduction of leptin after feeding in synthetic line 990 corresponded with elevated secretion of pancreatic enzymes and plasma insulin. The presented results suggest that the prandial secretion of pancreatic juice differs according to genotype, and the differences may be in part related to release of insulin.

Molecular characterisation of streptomycin-resistant Mycobacterium tuberculosis strains isolated in Poland

Primary drug resistance of Mycobacterium tuberculosis strains in Poland increased two-fold between 1997 and 2000. Among 3705 drug-resistant strains investigated in 2000, 169 were resistant to streptomycin alone or in combination with isoniazid, rifampicin and/or ethambutol. The molecular basis of streptomycin resistance for 88 (52%) of these strains in comparison with 15 susceptible controls was determined. The most prevalent mutation was the single substitution Lys43Arg in the rpsL gene, found in 30.7% of the strains analysed. However, as many as 51% of the strains investigated carried no mutation in the rpsL or rrs genes. The multiple mutations present in two Beijing family strains were also identified.

In vitro model of the outer blood–retina barrier

The outer blood-retina barrier (BRB) is formed by the retinal pigment epithelium (rpe) and functions similarly to the blood-brain barrier (BBB). In contrast to the BBB, which is composed of a myriad of capillaries, the rpe can in principle be prepared as an intact planar tissue sheet without disruption of its barrier and carrier functions. Both a rapid and gentle procedure to isolate porcine rpe and a method to implement the harvested rpe in drug penetration testing are presented. Enucleated eyes were flat-mounted and the RPE/choroid tissue sheets with or without the retina were isolated. Fluorescence microscopy based on double-labeling with propidium iodide/calcein and scanning electron microscopy revealed well-preserved cell and tissue architecture. For drug evaluation, specimens were immobilized as the interface between test compartments in a dual-chamber device. Ten different test agents were added to one chamber at defined concentrations. After an incubation time of 30 min at 37 degrees C permeated drug levels in both compartments were quantified by HPLC-tandem mass spectrometry or HPLC with fluorescence detection. Sodium fluorescein used as a barrier marker indicated that the rpe model had excellent seal integrity. The use of a representative subset of pharmaceuticals with known BBB permeability characteristics demonstrated that the rpe model had a large permeability dynamic range (factor >350). These findings showed that the model represents a valuable tool for the investigation of the blood barrier penetration of test compounds.

Drug-resistant tuberculosis in Poland in 2000: second national survey and comparison with the 1997 survey

SETTING

Three years after the last survey of drug-resistant tuberculosis in Poland, a nationwide survey was conducted by the National Tuberculosis Reference Laboratory in cooperation with all TB laboratories.

OBJECTIVE

To determine the prevalence and patterns of primary and acquired drug resistance among Mycobacterium tuberculosis isolates recovered from tuberculosis patients in Poland in 2000 and to compare the results with an earlier survey carried out in 1997.

DESIGN

In a prospective survey based on the questionnaires and strains of M. tuberculosis from all 16 regional centres participating in the study, 3705 questionnaires and cultures were obtained from 3037 new and 668 previously treated patients excreting TB bacilli during the 12-month period of 2000. Tests of resistance to isoniazid, rifampicin, streptomycin and ethambutol were performed using Löwenstein-Jensen and the Bactec system.

RESULTS AND CONCLUSION

Compared with the previous survey in 1997, the current survey showed a twofold increase in tuberculosis resistance in new cases: any resistance was 3.6% in 1997 vs. 6.1% in 2000 (P < 0.001), multidrug resistance was 0.6% vs. 1.2% (P < 0.01), and no cases of four-drug resistance in 1997 vs. 15 cases in 2000. No statistical differences were observed in the rate of acquired resistance in both surveys.

[Direct detection of mycobacterium tuberculosis complex in clinical specimens by gen-probe amplified direct test]

The amplified Mycobacterium tuberculosis direct test (MTD) (Gen-Probe Inc., San Diego, CA, USA) is a rapid technique of nucleic acid amplification which can be used directly on processed clinical specimens. It is based on the enzymatic amplification of ribosomal RNA via DNA intermediates, with detection of amplified product by an acridinum-ester-labeled DNA probe. The purpose of this study was to evaluate the clinical utility of this test for diagnosis of tuberculosis by comparing the sensitivity and specificity of the test with acid-fast smear, mycobacterial culture and clinical evaluation. The study included 399 specimens from patients, suspected of Tb which were submitted to the microbiological laboratory of our Institute over a 12 months period. Compared with bacterioscopy, conventional culture on L-J and rapid systems of cultivation (Bactec-450 Tb, MB/Bact, Bactec 960 MGIT) MTD had a sensitivity 93.2% and specificity 98.5%. We conclude, that MTD test which is completed within 6-8 hours, when used rationally, mainly in conjunction with routine smear and culture is a useful, rapid diagnostic test for suspected tuberculosis patients.

Improving the description of the retinal vasculature and patient history taking for monitoring systemic hypertension

Systemic hypertension is an important public health concern. If optometrists are to perform a more active role in the detection and monitoring of high blood pressure (BP), there is a need to improve the consistency of describing the retinal vasculature and to assess patient's ability to correctly report the diagnosis of hypertension, its control and medication. One hundred and one patients aged > 40 years were dilated and had fundus photography performed. BP was measured and a self-reported history of general health and current medication was compared with the records of their general practitioner (GP). The status of the retinal vasculature was quantified using a numeric scale by five clinicians and this was compared to the same evaluation performed with the aid of a basic pictorial grading scale. Image analysis was used to objectively measure the artery-to-vein (A/V) ratio and arterial reflex. Arteriolar tortuosity and calibre changes were found to be the most sensitive retinal signs of high BP. Using the grading scale to describe the retinal vasculature significantly improved inter- and intra-observer repeatability. Almost half the patients examined were on medication for high BP or cardiovascular disease. Patients' ability to give their complete medical history was poor, as was their ability to recall what medication they had been prescribed. GPs indicated it was useful to receive details of their patient's BP when it was > 140/90 mmHg. The use of improved description of the retinal vasculature and stronger links between optometrists and GPs may enhance future patient care.

Sequences of polypeptide antibiotics stilboflavins, natural peptaibol libraries of the mold Stilbella flavipes

From the culture broths of the mold Stilbella flavipes CBS 146.81, a mixture of polypeptides could be isolated by adsorption on XAD polystyrene resin and purified by Sephadex LH-20 chromatography. Using preparative thin-layer chromatography (TLC) three groups of peptides, named stilboflavins (SF) A, B, and C could be separated. Each of the groups showed microheterogeneity when investigated by high-performance liquid chromatography (HPLC). Employing on-line HPLC-electrospray ionization tandem mass spectrometry in the positive and negative ionization mode, together with gas chromatography-selected ion monitoring mass spectrometry, enantioselective GC and quantitative amino acid analysis, the sequences of stilboflavins A and B could be determined. Exchange of Glu in stilboflavins A peptides (acidic) against Gln in stilboflavins B peptides (neutral) is the rational for different polarity of the peptide groups and their separatability by TLC. Since SF A and B are bioactive N-acetylated 20-residue peptides with a high proportion of alpha-aminoisobutyric acid and C-terminal bonded amino alcohols (either leucinol, isoleucinol or valinol) the peptides belong to the group of peptaibol antibiotics.

Pkd1 unusual DNA conformations are recognized by nucleotide excision repair

The 2.5-kilobase pair poly(purine.pyrimidine) (poly(R.Y)) tract present in intron 21 of the polycystic kidney disease 1 (PKD1) gene has been proposed to contribute to the high mutation frequency of the gene. To evaluate this hypothesis, we investigated the growth rates of 11 Escherichia coli strains, with mutations in the nucleotide excision repair, SOS, and topoisomerase I and/or gyrase genes, harboring plasmids containing the full-length tract, six 5'-truncations of the tract, and a control plasmid (pSPL3). The full-length poly(R.Y) tract induced dramatic losses of cell viability during the first few hours of growth and lengthened the doubling times of the populations in strains with an inducible SOS response. The extent of cell loss was correlated with the length of the poly(R.Y) tract and the levels of negative supercoiling as modulated by the genotype of the strains or drugs that specifically inhibited DNA gyrase or bound to DNA directly, thereby affecting conformations at specific loci. We conclude that the unusual DNA conformations formed by the PKD1 poly(R.Y) tract under the influence of negative supercoiling induced the SOS response pathway, and they were recognized as lesions by the nucleotide excision repair system and were cleaved, causing delays in cell division and loss of the plasmid. These data support a role for this sequence in the mutation of the PKD1 gene by stimulating repair and/or recombination functions.

Detection, aetiology and management of conjunctival intraepithelial neoplasia

Conjunctival intraepithelial neoplasia (CIN) are considered to be the third most common ocular tumour and the most common tumour of the ocular surface. Due to their malignant potential, they must be carefully differentially and promptly treated. A recurrence rate of approximately 30% leads to the need for monitoring of patients even after successful treatment. This article presents several cases of CIN and reviews their histopathology, aetiology, appearance, differential diagnosis and management. Typical patient presentations and prognoses are also discussed.

Length of CTG.CAG repeats determines the influence of mismatch repair on genetic instability

We showed previously that mutations in methyl-directed mismatch repair of Escherichia coli reduced the occurrence of large deletions in (CTG.CAG)(175) repeats contained on plasmids. By contrast, other workers reported that mutations in mismatch repair increase the frequency of small-length changes in the shorter (CTG.CAG)(64). Using plasmids with a variety of lengths and purity of (CTG.CAG) repeats, we have resolved these apparently conflicting observations. We show that all lengths of (CTG.CAG) repeats are subject to small-length changes (<eight repeats) upon inactivation of the mismatch repair pathway. However, large deletions (>eight repeats) in (CTG.CAG)(n) occur more readily in cells with active mismatch repair. The frequency of large deletions is proportional to the tract length; in our assays they become prominent in tracts greater than 100 repeats. Interruptions in repeat purity enhance the occurrence of large deletions. In addition, we observed a high level of incidence of deletions in (CTG.CAG) repeats for cultures passing repeatedly through stationary phase during long-term growth experiments of all strains (i.e. with active or inactive mismatch repair). These results agree with current theories on mismatch repair acting on DNA slippage events that occur in DNA triplet-repeats.

New sequences and new fungal producers of peptaibol antibiotics antiamoebins

Mixtures of the microheterogeneous 16-mer peptaibol antibiotics called antiamoebins (AAM) have been isolated from the culture broths of strains of the filamentous fungi Stilbella erythrocephala ATCC 28144, Stilbella fimetaria CBS 548.84 and Gliocladium catenulatum CBS 511.66. Sequences were determined using on-line HPLC together with positive- and negative-ion electrospray ionization mass spectrometry. Some characteristic features are recognized in the mass spectrometric fragmentation pattern of AAM. From a sample originally used for sequencing AAM (from Hindustan Antibiotics, Ltd., Pimpri, Poona-411018, India), and a sample of AAM commercially available (from Sigma Chemicals, St. Louis, MO, USA) HPLC elution profiles and sequences were assigned. Further, sequences of AAM previously isolated from Emericellopsis synnematicola CBS 176.60 and Emericellopsis salmosynnemata CBS 382.62 were determined. The peptide designated AAM I was the most abundant in all isolates and its structure could be confirmed. AAM II was detectable as a minor component (1.9%) only in the original sample of AAM, but not in the other isolates. The structures of AAM III, IV and V, which had previously been partly assigned, were definitely established, and the new sequences AAM VI-XVI were elucidated. AAM showing Phe1/Leu1 or Phe1/Val1 exchange, respectively, are produced in amounts only by S. erythrocephala. Sequences, HPLC elution profiles ('fingerprints') and relative amounts of peptides of all isolates were correlated.

Detection of new sequences of peptaibol antibiotics trichotoxins A-40 by on-line liquid chromatography-electrospray ionization mass spectrometry

Using high-performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometry (ESI-MS) the sequences of the microheterogeneous peptide mixture of the 18-residue "peptaibol" antibiotics trichotoxins A-40, isolated from the mold Trichoderma viride strain NRRL 5242, were reinvestigated. The structures of two major and one minor component [J. Chromatogr., 296 (1984) 236] could be confirmed and hitherto not known sequences of a further major and two minor peptides could be determined. It is demonstrated that ESI-MS in the positive ionization mode is advantageously completed by applying negative ionization. The methods used make possible the sequence determination of components of peptaibols without previous isolation and allow, in certain cases, sequencing of peptides which are incompletely or not resolved by HPLC.

Structures of trichovirins II, peptaibol antibiotics from the mold Trichoderma viride NRRL 5243

From the culture broth of the mold Trichoderma viride NRRL 5243 a mixture of polypeptides, named trichovirins (TV), could be isolated and purified by chromatography on XAD-2 adsorber resin and Sephadex LH-20 gel. Chromatography on silica gel using chloroform/methanol 8:2 as eluent provided a mixture of peptides named TV I. Subsequent elution with chloroform/methanol 1:1 yielded a second group of peptides named TV II. That group could be separated into individual components by repetitive HPLC on an octadecylsilyl and a fluorocarbon stationary phase. The sequences of 12 peptides of TV II could be determined by electrospray ionization tandem mass spectrometry of isolated peptides and gas chromatography-mass spectrometry of methanolysates. The N-termini of the 18-mer peptides are acetylated and the C-termini consist of leucinol. Owing to the presence of alpha-aminoisobutyric acid (Aib) residues and the bactericidal and hemolytic activity, the peptides belong to the family of peptaibol antibiotics.

Use of patient-specific estimates in patient evaluation and rehabilitation

For a number of years we have been using open-ended questionnaires in the assessment of hearing disability and handicap, tinnitus complaint behaviour together with shortcomings and benefits of various rehabilitative interventions. More recently we have applied this approach to positive experiences reported by adults who have developed a hearing impairment and to the use of silence or social withdrawal as a communication tactic. In addition, we have asked individuals to rate the magnitude of each of their listed disabilities, handicaps, shortcomings, etc., on a scale to provide a qualitative assessment of each of these elements important to the individual. Such a procedure can be repeated after the intervention to measure changes in such estimates. This approach can thus highlight for the therapist, those elements of the patients' problems which are being well or poorly addressed and hence help them to concentrate their effort on the latter. Results obtained using this technique are presented and discussed.

Genomic fingerprinting of Proteus species using repetitive sequence based PCR (rep-PCR)

Three Proteus species P. vulgaris, P. mirabilis and P. penneri have been characterized by repetitive sequence-based PCR. Four families of repetitive sequence based primers REP, ERIC, BOXA1R and BOXA2R, give specific patterns for each Proteus species. Species differentiation was best afforded using BOXA2R for detection of P. mirabilis, either REP-Dt or BOXA1R primers for detection of P. penneri and ERIC primer pair for P. vulgaris.

An analysis of the communication tactics used by hearing-impaired adults

The aim of this study was to establish whether and to what degree certain types of communication strategies (hearing tactics) used by hearing-impaired adults could be shown to co-occur, and to find out which strategies were more likely to be used in which type of communicative situations. A consecutive series of 100 patients attending an audiological rehabilitation clinic was given a questionnaire asking how often they used each of five different hearing tactics in 11 different situations. 'Avoidance' and 'request for repetition' were the tactics used most commonly. 'Pretending to hear/understand' and 'positioning self to improve hearing' were used less frequently, with 'interruption' the least commonly used. There was some association between tactics and situations but no clear picture emerged. In a reassessment of our methodology and results, we suggest that the future research of communication strategies would benefit from a sociolinguistic approach based on the qualitative analysis of naturally occurring discourse (conversation) of hard-of-hearing people, focusing on the use of different strategies in relation to communicators' goals in interaction.

Nucleotide excision repair affects the stability of long transcribed (CTG*CAG) tracts in an orientation-dependent manner in Escherichia coli

The influence of nucleotide excision repair (NER), the principal in vivo repair system for DNA damages, was investigated in Escherichia coli with uvrA, uvrB and uvrAuvrB mutants with the triplet repeat sequences (TRS) involved in myotonic dystrophy, the fragile X syndrome and Friedreich's ataxia. (CTG*CAG)175was more stable when the (CTG) strand was transcribed than when the (CAG) strand was transcribed in the alternate orientation. A lack of the UvrA protein dramatically increases the instability of this TRS in vivo as compared with the stability of the same sequence in uvrB mutant, which produces an intact UvrA protein. We propose that transcription transiently dissociates the triplet repeat complementary strands enabling the non-transcribed strand to fold into a hairpin conformation which is then sufficiently stable that replication bypasses the hairpin to give large deletions. If the TRS was not transcribed, fewer deletions were observed. Alternatively, in the uvrA-mutant, the hairpins existing on the lagging strand will suffer bypass DNA synthesis to generate deleted molecules. Hence, NER, functionally similar in both prokaryotes and eukaryotes, is an important factor in the genetic instabilities of long transcribed TRS implicated in human hereditary neuro-logical diseases.

Small slipped register genetic instabilities in Escherichia coli in triplet repeat sequences associated with hereditary neurological diseases

Genetic instability investigations on three triplet repeat sequences (TRS) involved in human hereditary neurological diseases (CTG.CAG, CGG.CCG, and GAA.TTC) revealed a high frequency of small expansions or deletions in 3-base pair registers in Escherichia coli. The presence of G to A polymorphisms in the CTG.CAG sequences served as reporters for the size and location of these instabilities. For the other two repeat sequences, length determinations confirmed the conclusions found for CTG.CAG. These studies were conducted in strains deficient in methyl-directed mismatch repair or nucleotide excision repair in order to investigate the involvement of these postreplicative processes in the genetic instabilities of these TRS. The observation that small and large instabilities for (CTG.CAG)175 fall into distinct size classes (1-8 repeats and approximate multiples of 41 repeats, respectively) leads to the conclusion that more than one DNA instability process is involved. The slippage of the complementary strands of the TRS is probably responsible for the small deletions and expansions in methyl-directed mismatch repair-deficient and nucleotide excision repair-deficient cells. A model is proposed to explain the observed instabilities via strand misalignment, incision, or excision, followed by DNA synthesis and ligation. This slippage-repair mechanism may be responsible for the small expansions in type 1 hereditary neurological diseases involving polyglutamine expansions. Furthermore, these observations may relate to the high frequency of small deletions versus a lower frequency of large instabilities observed in lymphoblastoid cells from myotonic dystrophy patients.

The simultaneous production of both Hly- and Hpm-like hemolysins is characteristic of the Proteus penneri species

Clinical isolates of Proteus penneri were tested for the presence of genes encoding hemolytic activity. Strains possessing DNA sequences similar to the hlyCABD genes in Escherichia coli were found. Each secreted a 110 kDa protein which reacted with a specific anti-HlyA antiserum. Southern blotting analysis revealed that the HindIII restriction fragment pattern for the hlyCABD genes of these strains was conserved. Similarly, the chromosomal location of these genes is relatively conserved based on the pattern of NotI digested DNA fragments separated by pulsed field gel electrophoresis. One strain carried an additional copy of the hlyCABD determinant which was mapped on a second NotI genomic fragment. All strains contained also chromosomally encoded sequences related to the hpmBA genes originally cloned from Proteus mirabilis. All strains produced a 166 kDa exoprotein detected in immunoblots with a specific antiserum raised against HpmA hemolysin. The hpmBA genes were located on other NotI fragments than hlyCABD genes. In contrast to the other Proteae, the simultaneous production of both hemolysins seems to be a common characteristics of Proteus penneri isolates.

Transcription increases the deletion frequency of long CTG.CAG triplet repeats from plasmids in Escherichia coli

Induction of transcription into long CTG.CAG repeats contained on plasmids in Escherichia coli is shown to increase the frequency of deletions within the repeat sequences. This elevated genetic instability was detected because active transcription into the triplet repeat influenced the growth transitions of the host cell, allowing advantageous growth for cells harboring plasmids with deleted repeat sequences. The variety of deletion products observed in separate cultures suggests that transcription altered the metabolism of the DNA in a manner that produced random length changes in the repeat sequence. For cultures containing plasmids without active transcription into the triplet repeat, or those maintained in exponential growth, deletions occurred within the repeat at a lower frequency (5-20-fold lower). In these incubations the extent of deletions was proportional to the number of cell divisions and many repeat lengths were observed within each culture, suggesting that the decrease in average repeat length at long incubation times was due to multiple small deletions. These observations show that deletions within long CTG.CAG repeats contained on plasmids in E.coli occur via more than one pathway and their level of genetic instability is altered by the enzymatic processes occurring upon the DNA.

Relationship between Escherichia coli growth and deletions of CTG.CAG triplet repeats in plasmids

Instabilities that are intrinsic to natural repetitive DNA sequences produce high frequencies of length changes in vivo. Triplet repeats cloned in plasmids in Escherichia coli undergo expansions and deletions, and this instability is affected by multiple factors. We show that CTG-CAG repeats in plasmids can influence the growth of E. coli, which affects the observed stabilities. At extended growth periods, the observed frequencies of deletions were dramatically increased if the cells passed through stationary phase before subculturing. Deletions were particularly pronounced for a plasmid containing the longest repeat, 525 bp in total, with the CTG sequence as the lagging strand template for replication. Measurements of cell growth showed that the lag phase associated with E. coli growth was increased for cultures containing plasmids with long CTG-CAG repeats, particularly when the CTG-containing strand was the lagging template. High frequencies of deletions were observed because of a growth advantage of cells containing plasmids with deleted triplet repeats. Incubation conditions that reduced the bacterial growth-rate produced a decreased extent of deletions, presumably because they alleviated the growth advantage of cells harboring plasmids with deleted triplet repeats. The experimental observations were simulated by a model in which shorter triplet repeats provided a growth advantage due to a shorter lag phase. We demonstrate that the accumulation of deletions within repeating sequences during growth of E. coli can be prevented, and discuss these findings in relation to the studies of repetitive DNA sequences. These are the first observations to show a direct influence between a plasmid-based DNA sequence or structure and factors controlling bacterial growth.

Single-stranded DNA-binding protein enhances the stability of CTG triplet repeats in Escherichia coli

The stability of CTG triplet repeats was analyzed in Escherichia coli to identify processes responsible for their genetic instability. Using a biochemical assay for stability, we show that the absence of single-stranded-DNA-binding protein leads to an increase in the frequency of large deletions within the triplet repeats.

CTG triplet repeats from the myotonic dystrophy gene are expanded in Escherichia coli distal to the replication origin as a single large event

The expansion and contraction of CTG and CGG trinucleotide repeat sequences have been associated with several heritable genetic diseases. We developed a system for investigating the expansion of triplet repeat sequences in Escherichia coli in order to elucidate molecular mechanisms. Analysis of expanded regions using the interrupting CTA triplet sequence as a location marker within the CTG tract revealed that the expansion of large CTG repeats is one event rather than an accumulation of multiple small expansions and that the expansions occur more frequently in the region distal from the replication origin. Also, we showed that a loss of interruptions increases the expansion frequency. Thus, the instability of large triplet repeats in hereditary diseases occurs by a mechanism different from the instability in microsatellite sequences caused by defects in mismatch repair systems for certain sporadic cancers and hereditary non-polyposis colorectal cancers.

Mismatch repair in Escherichia coli enhances instability of (CTG)n triplet repeats from human hereditary diseases

Long CTG triplet repeats which are associated with several human hereditary neuromuscular disease genes are stabilized in ColE1-derived plasmids in Escherichia coli containing mutations in the methyl-directed mismatch repair genes (mutS, mutL, or mutH). When plasmids containing (CTG)180 were grown for about 100 generations in mutS, mutL, or mutH strains, 60-85% of the plasmids contained a full-length repeat, whereas in the parent strain only about 20% of the plasmids contained the full-length repeat. The deletions occur only in the (CTG)180 insert, not in DNA flanking the repeat. While many products of the deletions are heterogeneous in length, preferential deletion products of about 140, 100, 60, and 20 repeats were observed. We propose that the E. coli mismatch repair proteins recognize three-base loops formed during replication and then generate long single-stranded gaps where stable hairpin structures may form which can be bypassed by DNA polymerase during the resynthesis of duplex DNA. Similar studies were conducted with plasmids containing CGG repeats; no stabilization of these triplets was found in the mismatch repair mutants. Since prokaryotic and human mismatch repair proteins are similar, and since several carcinoma cell lines which are defective in mismatch repair show instability of simple DNA microsatellites, these mechanistic investigations in a bacterial cell may provide insights into the molecular basis for some human genetic diseases.

[Effect of 16-week use of salmeterol on ECP levels, pulmonary function tests and bronchial hyperreactivity in patients with chronic obstructive lung disease]

The aim of the study was to compare the influence of salmeterol on lung function tests (VC, FEV1), bronchial hyperreactivity (PC20) and eosinophil cationic protein (ECP) level in serum and in sputum in 10 patients with COPD. FEV1 was less than or equal 70% of predicted values but greater than 0.6 L. FEV1%VC less or equal 60% (reversibility after 200 micrograms salbutamol between 5-15%. Patients were treated with 2 x 50 micrograms salmeterol for 16 weeks. Lung function test didn't change during the observation but hyperreactivity had decreased (0.08 + 0.1 microgram/ml before, 0.24 + 0.2 microgram/ml after 4 weeks and 0.4 + 0.16 microgram/ml after 16 weeks) ECP level had decreased in serum (53 +/- 24 micrograms/l before, 32 +/- 12 micrograms/l after 4 weeks and 36 +/- 13 micrograms/l after 16 weeks) and in sputum (2345 +/- 789 micrograms/g before 1342 +/- 894 micrograms/g after 4 weeks, 1742 mu 698 micrograms/g after 16 weeks). We concluded that salmeterol didn't change lung function test but decreased bronchial hyperreactivity and decreased ECP level in serum and sputum.

[Correlation of ECP levels in sputum and blood with parameters of airflow obstruction and hyperreactivity in patients with irreversible bronchial obstruction due to chronic bronchitis]

The aim of this study was to find if there was any correlation between the serum and sputum eosinophil cationic protein (ECP) concentrations with the parameters of airflow obstruction as well as degree of bronchial hyperreactivity. 18 patients aged 40-75 years with irreversible bronchial obstruction (FEV1 > 0.61 or < 70% of the predicted value, FEV1%VC < 60%) without eosinophilia and high hyperreactivity (PC20 0.02 mg/ml -0.4 mg/ml) were examined. The FEV1 reversibility after 400 micrograms MDI salbutamol was 5-10%. ECP was measured by radioimmunosorbent assay using the ECP RIA kit (Pharmacia). The range of the standard curve was 2-100 micrograms ECP/L, while all assays were run in duplicate. The bronchial challenge was performed with histamine. The challenge was stopped when the FEV1 had decreased by > 20%. Serum ECP concentrations ranged from 0.0001-0.063 mg/ml, whereas sputum ECP concentrations were between 0.0002-1.84 mg per g sputum. There was no correlation between sputum and serum ECP concentrations and the degree of hyperreactivity and were not related to the parameters of hyperreactivity and were not related to the parameters of airway obstruction.

Expansion and deletion of CTG repeats from human disease genes are determined by the direction of replication in E. coli

Several human hereditary neurological and neurodegenerative disease genes are associated with the expansion of CTG repeats. Here we show that the frequency of genetic expansions or deletions in Escherichia coli depends on the direction of replication. Large expansions occur predominantly when the CTGs are in the leading strand template rather than the lagging strand. However, deletions are more prominent when the CTGs are in the opposite orientation. Most deletions generated products of defined size classes. Strand slippage coupled with non-classical DNA structures may account for these observations and relate to expansion-deletion mechanisms in eukaryotic chromosomes for disease genes.

[Effect of salbutamol on left ventricular function and selected biochemical parameters in patients with bronchial asthma]

Many authors link increased mortality in course of bronchial asthma (BA) with the administration of excessive doses of beta-2 agonists, one of the causes considered being their cardiotoxic effect. The aim of the present study was to evaluate the effect of 0.5 mg intravenous bolus of salbutamol (S) on left ventricular (LV) function assessed by echocardiography and on the selected biochemical parameters: the activity of creatinine kinase (CK) and its cardiac specific isoenzyme (CK-MB), potassium (K+) and free fatty acids (FFA) serum concentration as well as partial arterial oxygen pressure (PaO2). The studied group consisted of 16 patients (pts)--12 males and 4 females, aged 36-60 yrs, mean 49.0 +/- 7 yrs with BA and moderate airway obstruction (FEV1%VC--60 +/- 7%). Pts with cardiac disorders were excluded from the study. Echocardiographic examination was performed before and 30 min after S injection. Biochemical determinations were carried out at 5 min., 30 min, 2 h, and 4 h following S administration. We found mean HR increase by 20 beats per min (p < 0.001) and mean systolic blood pressure elevation by 19 mmHg at 30 min (p < 0.001) after S. It was accompanied by significant increase of cardiac output (CO) from 5.7 +/- 1.5 to 8.4 +/- 1.8 l/min (p < 0.001) and mean rate of circumferential shortening (mVcf) from 1.48 +/- 0.27 to 1.88 +/- 0.43 (circ/sec), p < 0.01. Stroke volume (SV), ejection fraction (EF%), fractional shortening of LV (FS%) increased nonsignificantly.(ABSTRACT TRUNCATED AT 250 WORDS)

H-NS over-expression induces an artificial stationary phase by silencing global transcription

Bacteria organize their chromosomes in a complex interwound supercoiled structure called the nucleoid through the action of topoisomerases and a set of small (10-20 kDa) proteins. The two most abundant nucleoid-associated proteins are HU and H-NS. H-NS increases in abundance during stationary phase. Over-expression of HU is well tolerated and compatible with transcription and cell growth. Increasing the concentration of H-NS leads to a rapid silencing of global transcription and produces a growth-arrested state reminiscent of stationary phase. H-NS over-expression also induces a substantial loss of supercoiling in plasmid DNA during the time that transcription is arrested. Comparing the effects of over-expression of these two proteins gives some insight into the differential roles of these proteins in the activity of the chromosome. These observations are interpreted in a model of nucleoid organization.

Analysis of antibiotic resistance determinants in Proteus penneri

The plasmid profiles of 65 strains of Proteus penneri were analyzed to determine whether resistance was determined chromosomally or by plasmids. Only seven strains harboured one to three plasmids, although these strains exhibited resistance to a wide range of antibiotics. Markers for ampicillin and tetracycline resistance could be transferred to Escherichia coli by transformation. Plasmids carried resistance to chloramphenicol in two strains and resistance to sulfonamides in one strain. The result showed that resistance is determined chromosomally rather than by plasmids, however the possibility that these bacteria may acquire resistance plasmids which change their antibiotic susceptibility pattern cannot be excluded.

Creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) activity in serum before and after intravenous salbutamol administration of patients with bronchial asthma

The effect of salbutamol, a selective beta 2-adrenergic agonist, on creatine kinase (CK) and creatine kinase isoenzyme (CK-MB) activity in serum of 20 asthmatic patients was investigated. Venous blood was obtained 30 min, 2 h and 4 h after 0.5 mg salbutamol intravenous injection of 0.5 mg salbutamol. Total creatine kinase activity was assayed on a Technico RA-1000 analyzer with the IFCC recommended method. CK-MB activity was determined using a centrifugal analyzer (Cobas Fera, Roche, Switzerland). Reagent kits were provided by Boehringer Mannheim (FRG). We observed no increase of CK-activity after salbutamol, and found a statistically significant increase of CK-MB activity. Serum CK-MB activity before treatment was 13 +/- 10/IU/l after 30 minutes drug, 31.8 +/- 19 IU/l after 2 h 27.2 +/- 17.79 and after 4 h 22.6 +/- 12 IU/l. We conclude that salbutamol exerts a cardiotoxic effect.

Cell-free and cell-bound hemolytic activities of Proteus penneri determined by different Hly determinants

A collection of 45 Proteus penneri strains was characterized with respect to their hemolytic activity and representative cell-free or only cell-bound hemolysin possessing strains were chosen for further study. Extracellular Proteus penneri hemolysin, which was investigated earlier by hybridization, reacted with monospecific antiserum against alpha-hemolysin of Escherichia coli. In this paper we also show, using the colony hybridization technique, that the alpha-hemolysin-like determinant is widely distributed among Proteus penneri strains. Because one of the strains tested, which expressed a high activity of cell-bound hemolytic factor, did not carry such a Hly determinant, the presence of a second hemolysin is postulated. We cannot demonstrate any difference in hybridization patterns of alpha- and beta-hemolytic Proteus penneri strains and accumulation of the toxin molecule inside the cells was also not observed. The existence of another control mechanism, external to the hly operon, for hemolysin gene is suggested.

Topoisomerase mutants and physiological conditions control supercoiling and Z-DNA formation in vivo

The influence of topoisomerase I and gyrase mutations in Escherichia coli on the supercoiled density of recombinant plasmids and the stability of left-handed Z-DNA was investigated. The formation of Z-DNA in vivo by dC-dG sequences of different lengths was used to determine the effective plasmid supercoil densities in the mutant strains. The presence of Z-DNA in the cells was detected by linking number and EcoRI methylase inhibition assays. A change in the unrestrained superhelical tension in vivo directly effects the B- to Z-DNA transition. Alterations in the internal or external environment of the cells, such as the inactivation of gyrase or topoisomerase I, a gyrase temperature-sensitive mutant, or starvation of cells, have a dramatic influence on the topology of plasmids. Also, E. coli has significantly more superhelical strain than Klebsiella, Morganella, or Enterobacter. These studies indicate that linking deficiency and effective supercoil density are mutually independent variables of plasmid tertiary structure. A variety of factors, such as protein-DNA interactions, activity of topoisomerases, and the resulting supercoil density, contribute to the B to Z transition inside living cells.

Cytosine methylation enhances Z-DNA formation in vivo

The influence of cytosine methylation on the supercoil-stabilized B-Z equilibrium in Escherichia coli was analyzed by two independent assays. Both the M.EcoRI inhibition assay and the linking-number assay have been used previously to establish that dC-dG segments of sufficient lengths can exist as left-handed helices in vivo. A series of dC-dG plasmid inserts with Z-form potential, ranging in length from 14 to 74 base pairs, was investigated. Complete methylation of cytosine at all HhaI sites, including the inserts, was obtained by coexpression of the HhaI methyltransferase (M.HhaI) in cells also carrying a dC-dG-containing plasmid. Both assays showed that for all lengths of dC-dG inserts, the relative amounts of B and Z helices were shifted to more Z-DNA in the presence of M.HhaI than in the absence of M.HhaI. These results indicate that cytosine methylation enhances the formation of Z-DNA helices at the superhelix density present in E. coli. The B-Z equilibrium, in combination with site-specific base methylation, may constitute a concerted mechanism for the modulation of DNA topology and DNA-protein interactions.