New rapid test for prenatal detection of trisomy 21 (Down's syndrome): preliminary report

OBJECTIVE

To devise and evaluate a rapid screening method for detecting trisomy 21 (Down's syndrome) in samples of uncultured amniotic fluid cells.

DESIGN

Non-radioactive in situ hybridisation with HY128, a 500,000 base pair yeast artificial chromosome probe specific for chromosome 21. Blinded study of 12 karyotypically normal amniotic fluid samples and eight samples trisomic for chromosome 21.

SETTING

Cytogenetic and obstetric services at a tertiary referral centre, Copenhagen.

MAIN OUTCOME MEASURES

Time necessary to complete the test. Proportion of cell nuclei containing two and three hybridisation signals in karyotypically normal and abnormal amniotic fluid samples.

RESULTS

The test could be completed within three to four days after amniocentesis. In the normal samples a mean of 73% (range 61-82%) of the amniotic cell nuclei showed two hybridisation signals and 6% (0-18%) showed three signals. By contrast, among the trisomic samples 29% (19-38%) of the nuclei exhibited two signals and 48% (31-60%) showed three signals.

CONCLUSION

The technique clearly distinguished between normal and trisomic samples. Prenatal diagnosis with in situ hybridisation with chromosome specific probes was fast and may make it possible to screen for selected, aneuploidies. However, the technique is still at a preliminary stage and needs further evaluation and refinement.

Rapid prenatal diagnosis of trisomy 18 and triploidy in interphase nuclei of uncultured amniocytes by non-radioactive in situ hybridization

Two biotinylated chromosome-specific DNA probes were used to quantify the number of chromosomes 18 and 1 in uncultured amniocytes. Thirty-three samples of uncultured amniocytes were hybridized with a chromosome 18-specific DNA probe. Uncultured cells from two of the 33 samples were also hybridized with a chromosome 1-specific probe. Thirty of the samples were disomic with respect to chromosome 18; two samples were trisomic with respect to chromosome 18, and one sample was trisomic with respect to chromosomes 1 and 18. The two cases of trisomy 18 and the single case of triploidy were identified on uncultured cells within 48-72 h after amniocentesis. They were found among five samples from pregnant women who had amniocentesis because of an ultrasonographically identified fetal malformation. A trisomic karyotype could be diagnosed with certainty in uncultured amniocytes because the majority of the responding nuclei exhibited three hybridization signals. In normal cells, the majority of nuclei exhibited two signals. In no cases was there discordance between the genotype as predicted by in situ hybridization and that determined by cytogenetic analysis.

A method for shipboard treatment of multiple heat casualties

A method is presented for the treatment aboard ship of multiple patients afflicted with life-threatening heat illness, using an inflatable life raft cooling system. The potential benefits of this method include: (1) the utilization of readily available materials aboard U.S. Naval vessels; (2) the provision for rapid patient cooling by evaporation while maintaining patient safety and comfort; (3) the ability to treat many patients simultaneously with minimal attendant personnel; and (4) the maintenance of patient access allowing for monitoring and the administration of additional supportive measures.

Treatment of persistent postpartum HELLP syndrome with plasmapheresis

Thrombocytopenia, associated with microangiopathic disease, is one characteristic of severe preeclampsia. Thrombocytopenia and intravascular hemolysis usually resolve by postpartum days 4 to 5. When thrombocytopenia secondary to microangiopathic disease persists, plasmapheresis may be used to arrest and reverse the process. Three patients over a 24-month period were successfully treated with plasma exchange with fresh frozen plasma. Several investigators who have cared for patients with persistent thrombocytopenia associated with preeclampsia have concluded that early plasmapheresis may be useful therapy. Plasma exchange should also be considered as a therapeutic option when clinical deterioration occurs due to microangiopathic disease.

Evaluation of the E test for quantitative antimicrobial susceptibility testing of Helicobacter pylori

The Progressive Diagnostics Manufacturers epsilometer test (E test; AB Biodisk, Solna, Sweden), a quantitative variant of the disk diffusion technique, was evaluated comparatively to an agar dilution method for the antimicrobial susceptibility testing of Helicobacter pylori. A collection of 79 H. pylori clinical strains, including isolates with known resistance to various antimicrobial agents, was tested against 12 different antimicrobial agents. All strains were tested on Columbia agar supplemented with 10% horse blood. Plates were incubated at 37 degrees C in microaerobic atmosphere (5% O2, 10% CO2), and readings were done after 3 days of incubation. In general, E test MICs were easy to interpret and the correlation between MICs by the agar dilution method and the E test was good, with 86 and 99.5% of results being within, respectively, 1 and 2 log2 dilution steps in a total of 936 tests. All strains of H. pylori with documented resistance to the tested agents were detected by the E test. Thus, the E test appears to be an easy and reliable method for determination of MICs of antibiotics for H. pylori, and it may offer an interesting alternative to MIC determination by the agar dilution technique.

Gas-liquid chromatographic analysis of cellular fatty acid methyl esters in Aeromonas species

The cellular fatty acids of 39 strains belonging to the genus Aeromonas (Aeromonas hydrophila, Aeromonas caviae, Aeromonas sobria, Aeromonas media, Aeromonas schubertii, Aeromonas veronii) were determined by high resolution gas-liquid chromatography. The fatty acid profiles were characterized by major amounts (60% or more) of one saturated (hexadecanoic acid = 16:0) and two unsaturated (hexadecenoic acid = 16:1 and octadecenoic acid = 18:1) acids. While the majority of the strains of the six species exhibited, qualitatively, very similar fatty acid compositions, only minor and inconsistent differences could be observed which would be useful for a distinction of the different taxons. The following fatty acids were qualitatively identified: 12:0, i-13:0, 14:0, 3-OH 13:0, i-15:0, 15:0, 2-OH 14:0, 3-OH 14:0, i-16:0, 16:1, 16:0, i-17:1, i-17:0, a-17:0, 17:0 cyclopropane, 17:1, 17:0, 18:1 (3 isomers), 18:0 and i-20:0. Excellent congruence was found in reproducibility studies. Fatty acid analyses show a great homogeneity within the group and the technique does not appear to be the ideal method in distinguishing between Aeromonas species.

[Isolation of Vibrio alginolyticus from a leg ulcer]

An organism presenting the characteristics of Vibrio alginolyticus was isolated from a cutaneous leg ulcer in a 67-year-old woman. The origin of this halophilic bacterium remains unknown. The clinical observation and the bacteriological findings are presented and commented.

Catheter infection caused by an unusual pathogen, Agrobacterium radiobacter

The genus Agrobacterium is composed of several phytopathogenic species occurring worldwide in soils. One nontumorigenic species, Agrobacterium radiobacter, has occasionally been isolated from clinical specimens, but its pathogenic role in these cases has been difficult to ascertain since agrobacteria are usually isolated in association with other bacteria. We report the case of a central venous catheter infection and present the characteristics of A. radiobacter.

Cassette mutagenic analysis of the yeast invertase signal peptide: effects on protein translocation

The coding sequence of the SUC2 locus was placed under the control of the constitutive ADH1 promoter and transcription terminator in a centromere-based yeast plasmid vector from which invertase is expressed in a Suc- strain of Saccharomyces cerevisiae. Mutants in the signal peptide sequence were produced by replacing this region of the gene with synthetic oligonucleotide cassettes containing mixtures of nucleotides at several positions. The mutants could be divided into three classes on the basis of the ability to secrete invertase. Class I mutants produced secreted invertase but in reduced amount. The class II mutant, 4-55B, also exhibited reduced a level of invertase, but a significant fraction of the enzyme was intracellular. Class III mutants were partially defective in translocation from the cytoplasm to the endoplasmic reticulum and produced enzymatically active, unglycosylated preinvertase in the cytoplasm. Class III mutant preinvertases were also defective in translocation across canine pancreas microsomes. These results suggested that the reduced level of invertase resulted from proteolytic degradation of inefficiently transported intermediates. Comparison of the sequences of the mutant signal peptides indicated that amino acids at the extreme amino terminus and adjacent to the cleavage site play a crucial role in the secretory process when combined with a mutation within the hydrophobic core.

The use of gene-fusions to determine membrane protein topology in Saccharomyces cerevisiae

We have used protein-fusions to study in Saccharomyces cerevisiae the topology and integration of arginine permease. Since this membrane protein does not contain a cleavable signal sequence, we sought to identify the first internal signal by, initially, fusing the cytoplasmic enzyme, galactokinase, to various positions along the amino-terminal region, and then measuring in vitro the translocation of galactokinase across the membrane of the endoplasmic reticulum. Five fusion proteins were examined that contained, progressively, zero to four hydrophobic segments. The galactokinase moiety of fusion 5, but not fusions 1-4, was translocated. Fusion 4 differed from 5 by only the fourth hydrophobic segment, indicated that this region contains the first internal signal. From this we conclude that hydrophobic segment IV spans the membrane, and that the hydrophilic domain amino-terminal to it lies on the cytoplasmic side of the membrane. If any of the first three segments actually span the membrane, then they probably integrate by a mechanism that differs from segment IV.

Small ribonucleoproteins in Schizosaccharomyces pombe and Yarrowia lipolytica homologous to signal recognition particle

We have partially purified ribonucleoproteins (RNPs) from Schizosaccharomyces pombe and Yarrowia lipolytica with properties resembling those of mammalian signal recognition particle (SRP). In both species of yeast we have identified a single major RNA species in the size range of SRP RNA (256 nucleotides in S. pombe and 270 nucleotides in Y. lipolytica) present in postribosomal salt extracts of the cytoplasm. The RNPs containing these RNAs sediment in sucrose gradients at 11 S and 10 S for S. pombe and Y. lipolytica, respectively. Analysis of genomic clones of these RNAs has revealed that (i) they are encoded by single copy genes; (ii) they share two short conserved sequences that match the A and B boxes defined for polymerase III promoters; (iii) they can be folded into secondary structures that closely match that defined by phylogenetic analysis of higher eukaryotic SRP RNAs; and (iv) they show primary sequence conservation in short regions predicted to be single stranded. Both of the yeast RNAs bind under stringent conditions to canine SRP proteins. Most importantly, RNase protection of the S. pombe RNA by the individual canine SRP proteins, p19 and p68/72, shows that the proteins recognize homologous elements of the mammalian and yeast RNA. Taken together these data suggest strongly that we have identified yeast SRP homologues.

Postoperative infant septicemia caused by Pseudomonas luteola (CDC group Ve-1) and Pseudomonas oryzihabitans (CDC group Ve-2)

Pseudomonas luteola (CDC group Ve-1) and Pseudomonas oryzihabitans (CDC group Ve-2) were both isolated from the same blood culture of a 5-month-old infant, 8 days after open-heart surgery. He quickly responded to appropriate antibiotics. Carbon substrate assimilation tests and fatty acid analysis clearly differentiated these two rarely pathogenic organisms.

Prepro-carboxypeptidase Y and a truncated form of pre-invertase, but not full-length pre-invertase, can be posttranslationally translocated across microsomal vesicle membranes from Saccharomyces cerevisiae

We have determined that prepro-carboxypeptidase Y and a truncated form of pre-invertase can be translocated across the yeast microsomal membrane post-translationally in a homologous in vitro system. The yeast secretory protein prepro-alpha-factor which was previously shown to be an efficient posttranslational translocation substrate is therefore not unique in this regard, but rather the yeast ER protein translocation machinery is generally capable of accepting substrates from a ribosome-free, soluble pool. However, within our detection limits, full-length pre-invertase could not be translocated posttranslationally, but was translocated co-translationally. This indicates that not every fully synthesized pre-protein can use this pathway, presumably because normal or aberrant folding characteristics can interfere with translocation competence.

In vitro susceptibility of Alcaligenes denitrificans subsp. xylosoxidans to 24 antimicrobial agents

The in vitro susceptibilities of 37 clinical isolates of Alcaligenes denitrificans subsp. xylosoxidans to 24 antimicrobial agents were determined. Imipenem was the only drug with consistent activity (MIC for 90% of isolates, 2 micrograms/ml). Piperacillin, ticarcillin-clavulanic acid, ceftazidime, and co-trimoxazole were active against most strains. All the isolates were resistant to ampicillin, cefazolin, cefuroxime, cefamandole, cefotetan, ceftriaxone, cefotaxime, aztreonam, amdinocillin, and temocillin. Most isolates were resistant to the aminoglycosides tested, including amikacin. Lack of activity was also observed for all new 4-quinolone antimicrobial agents.

Detection of Gardnerella vaginalis in vaginal specimens by direct immunofluorescence

The preparation of a fluorescein-labeled Gardnerella vaginalis polyclonal antibody is described, and its usefulness is assessed for the detection of this microorganism in vaginal samples obtained from 263 women attending the gynecological department of a general hospital, 66 of whom harbored an intrauterine device. The direct immunofluorescence technique was positive for G. vaginalis in 21% of the specimens, whereas only 12.5% of the total bacteriological cultures were positive. The frequency was higher in patients harboring intrauterine devices since 34.8% exhibited positive immunofluorescence and 30.3% exhibited positive cultures.

Septicemia caused by Sphingobacterium multivorum

Sphingobacterium multivorum was isolated in pure culture from the blood of a man undergoing chemotherapy for a lymphoma. He responded to appropriate antibiotics and later showed a significant rise in specific serum antibodies. Carbon substrate assimilation tests and fatty acid analysis proved useful in identifying the organism precisely.

Pseudomonas stutzeri pneumonia and septicemia in a patient with multiple myeloma

A case of septicemia caused by Pseudomonas stutzeri belonging to the unusual biotype Vb-3 in a patient with multiple myeloma is described. The origin of the septicemia was attributed to a community-acquired pneumonia. The bacteriology and pathogenicity of P. stutzeri are reviewed.

Oral lormetazepam in premedication. A comparison with diazepam

Lormetazepam, a relatively new benzodiazepine was compared in a randomised, double blind trial with diazepam for its effectiveness as an oral premedicant drug. A scoring system was used to assess sedation, relief of anxiety, nausea, dizziness and cardiovascular effects in two groups of patients having orthopaedic operations. Some statistical indication that lormetazepam has a greater anxiolytic effect than diazepam was found, but in assessing total effect using a known scoring system, no difference was demonstrated between the two drugs.

In vitro protein translocation across the yeast endoplasmic reticulum: ATP-dependent posttranslational translocation of the prepro-alpha-factor

The in vitro synthesized precursor of the alpha-factor pheromone, prepro-alpha-factor, of Saccharomyces cerevisiae was translocated across yeast microsomal membranes in either a homologous or a wheat germ cell free system. Translocated prepro-alpha-factor was glycosylated, sedimented with yeast microsomal vesicles, and was protected from digestion by added protease, but was soluble after alkaline sodium carbonate treatment. Thus prepro-alpha-factor was properly sequestered within yeast microsomal vesicles, but was not integrated into the lipid bilayer. In marked contrast to protein translocation across mammalian microsomal membranes, translocation of prepro-alpha-factor across yeast microsomal membranes could occur posttranslationally. This reaction required protein components in the yeast microsomal fraction that could be inactivated by alkylation or proteolysis, was ATP-dependent, and was insensitive to the presence of a variety of uncouplers and ionophores.

Attempted suicide in Denmark. III. Assessment of repeated suicidal behaviour

Ninety-nine patients, randomly chosen among hospital admitted suicide attempters, were initially interviewed at the Department of Psychiatry, Odense University Hospital, Denmark, and then followed up for a period of about 3 years. Half of the patients repeated the attempt in the follow-up period, mostly in the first year. Ten patients committed suicide, half of them in the first 3 months after the interview, shortly after discharge from hospital. The majority of the repeaters were living alone, while those that committed suicide were mostly married women aged 50-60 years. Other characteristic features for the repeaters were previous suicidal behaviour and suicidal behaviour among relatives. Many had a psychiatric record and expressed chronic somatic complaints. Around the time of the attempt, many expressed hopelessness, isolation and suicidal ideation. Pierce's Suicide Intent Scale performed poorly due, in particular, to low specificity. Future work will focus on objective risk factors, those indicated here and others, in order to establish an up-to-date background for assessment and management.

Campylobacter fetus peritonitis followed by septicaemia in a patient on continuous ambulatory peritoneal dialysis

A 62-year-old man being treated by continuous ambulatory peritoneal dialysis (CAPD) developed peritonitis due to Campylobacter fetus subspecies fetus (intestinalis), an organism seldom isolated in such circumstances. After appropriate and apparently effective antibiotic therapy, the patient relapsed 6 weeks later with septicaemia. Blood cultures yielded a similar organism, thereby suggesting a clinically silent metastatic infection during the episode of peritonitis, probably at an old arteriovenous fistula. Parenteral tobramycin followed by oral erythromycin achieved a complete cure of this unusual complication.

Attempted suicide in Denmark. I. Some basic social characteristics

During a 6 months' period, 99 persons, randomly chosen among patients admitted for attempted suicide to the Department of Psychiatry, Odense University Hospital, were interviewed. This paper, which is the first in a series, deals with the theoretical and methodological background of the survey and the validity of the sample and also with some basic social characteristics of the suicide attempters. The majority of the suicide attempters were found to be single and many of them were living alone or alone with children. The sample could also be characterized by a low level of vocational education and by lack of association with the labour market. The suicide attempters could not, however, be unequivocally described as being in bad financial circumstances, neither were they solely from the lower social classes; the social status profile of the suicide attempters was closer to the status profile of suiciders, with relatively many persons from both upper and lower classes and few from the middle class.

Pseudomonas paucimobilis peritonitis in patients treated by peritoneal dialysis

Pseudomonas paucimobilis has rarely been reported as an opportunistic human pathogen. We report the isolation of this organism in two patients who developed peritonitis during the course of intermittent or continuous ambulatory peritoneal dialysis. The origin of the infection was related to contamination of the dialysate in the first patient but could not be determined in the second case.

Detection of beta-glucuronidase in lactose-fermenting members of the family Enterobacteriaceae and its presence in bacterial urine cultures

Four hundred strains of lactose-fermenting Enterobacteriaceae were tested for hydrolysis of p-nitrophenyl-beta-D-glucopyranosiduronic acid, the chromogenic enzyme substrate of beta-glucuronidase. Escherichia coli was found to be homogeneous with respect to beta-glucuronidase: more than 94% of the examined E. coli strains were positive, whereas none of the other lactose-fermenting strains possessed beta-glucuronidase activity. The qualitative beta-glucuronidase test, as rapid and simple as the o-nitrophenyl-beta-D-galactopyranosidase test, proved to be of diagnostic value, especially in the identification of E. coli in primary urine cultures. No significant differences were observed in the results of experiments in which either substrate-impregnated disks prepared in the laboratory or commercially available tablets were used.

Invertase beta-galactosidase hybrid proteins fail to be transported from the endoplasmic reticulum in Saccharomyces cerevisiae

The yeast SUC2 gene codes for the secreted enzyme invertase. A series of 16 different-sized gene fusions have been constructed between this yeast gene and the Escherichia coli lacZ gene, which codes for the cytoplasmic enzyme beta-galactosidase. Various amounts of SUC2 NH2-terminal coding sequence have been fused in frame to a constant COOH-terminal coding segment of the lacZ gene, resulting in the synthesis of hybrid invertase-beta-galactosidase proteins in Saccharomyces cerevisiae. The hybrid proteins exhibit beta-galactosidase activity, and they are recognized specifically by antisera directed against either invertase or beta-galactosidase. Expression of beta-galactosidase activity is regulated in a manner similar to that observed for invertase activity expressed from a wild-type SUC2 gene: repressed in high-glucose medium and derepressed in low-glucose medium. Unlike wild-type invertase, however, the invertase-beta-galactosidase hybrid proteins are not secreted. Rather, they appear to remain trapped at a very early stage of secretory protein transit: insertion into the endoplasmic reticulum (ER). The hybrid proteins appear only to have undergone core glycosylation, an ER process, and do not receive the additional glycosyl modifications that take place in the Golgi complex. Even those hybrid proteins containing only a short segment of invertase sequences at the NH2 terminus are glycosylated, suggesting that no extensive folding of the invertase polypeptide is required before initiation of transmembrane transfer. beta-Galactosidase activity expressed by the SUC2-lacZ gene fusions cofractionates on Percoll density gradients with ER marker enzymes and not with other organelles. In addition, the hybrid proteins are not accessible to cell-surface labeling by 125I. Accumulation of the invertase-beta-galactosidase hybrid proteins within the ER does not appear to confer a growth-defective phenotype to yeast cells. In this location, however, the hybrid proteins and the beta-galactosidase activity they exhibit could provide a useful biochemical tag for yeast ER membranes.

Isolation of Serratia ficaria from human clinical specimens

Serratia ficaria was isolated from sputum in a 62-year-old man and from tracheal aspiration fluid in a 62-year-old woman with acute respiratory distress. These strains are the second and third isolations of S. ficaria from human sources. The case reports are presented, together with the laboratory findings and the biochemical activities of the isolates.