Have the geriatricians been told?
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Aged↗
Biomedical subjects
R J Russell
Publications and source records attributed to R J Russell.
Molecular analysis of duplicated esterase genes in Drosophila melanogaster.
Genomic clones containing sequences homologous to an esterase 6 (Est-6) cDNA clone were isolated from a library of Drosophila melanogaster DNA. Comparison of the genomic and cDNA sequences revealed that the Est-6 gene comprises two exons, one of 1,387 bp and one of 248 bp, separated by a short intron of 51 bp. Further sequencing revealed the presence of a tandem duplication of the Est-6 gene (denoted Est-P) which also has an exon of 1,387 bp and an exon of 248 bp, separated by a short intron of 56 bp. The two genes show similarities of 64% and 60% at the DNA and protein levels, respectively. The coding regions of the genes are 197 bases apart, and presumptive 5' regulatory sequences of Est-P overlap at least the 3' noncoding region of Est-6. Transcripts homologous to Est-P were detected in late larvae and adults of each sex, whereas Est-6 transcripts are present in all life stages but are predominant in adult males. This suggests different physiological functions for the products of the two genes. Southern and Northern blot hybridization analyses of the 20-kb region surrounding the Est-6/Est-P duplication failed to detect any other duplicated esterase genes, although this region is actively transcribed.
Amino Acid Sequence↗
Transcriptional analyses of the uncoordinated region of Drosophila melanogaster.
RNA blotting experiments reveal that a genomic region encompassing the uncoordinated complementation group of Drosophila melanogaster produces two classes of transcripts. The first class contains five polyadenylated RNAs, of 4.35, 8.7, 9.0, 11.5, and 13.0 kb, and the second class contains a transcript of 7.3 kb that can be detected in both the total cellular and the poly(A)+ fractions. Transcripts of the first class are found predominantly in the early larval, pupal, and adult life stages, whereas the 7.3-kb species is present throughout the life cycle and is also found in the heads of adult flies. The two classes of RNAs derive from different combinations of exons. Analyses of RNAs derived from genotypes that are deficient for the uncoordinated complementation group and from seven uncoordinated mutant alleles support the suggestion that the uncoordinated gene (unc) has been isolated and encodes the multiple transcripts.
Alleles↗
Cloning and molecular characterization of the myxoma virus genome.
Restriction enzyme cleavage maps of the genomes of the Uriarra (Ur), Glenfield (GV), and Lausanne (Lu) strains of myxoma virus were deduced for the enzymes EcoRI, KpnI, BamHI, SalI, HindIII, BglI, PstI, and PvuII. Restriction maps for the three strains were indistinguishable with the exception of an additional KpnI site in the Lu genome at map position 38.8. Genomic DNA fragments were cloned into the plasmid vector pGEM-3 and the viral genome was determined to be 163.6 (+/- 0.2) kb in length. Covalently closed terminal fragments were identified by electrophoresis of "snapback" fragments and the 5.3 kb BglI end fragment was cloned after S1 nuclease digestion of the hairpin structure.
Blotting, Southern↗
Staphylococcus aureus bacteriophages mediating the simultaneous lysogenic conversion of beta-lysin, staphylokinase and enterotoxin A: molecular mechanism of triple conversion.
A new group of serotype F bacteriophages of Staphylococcus aureus has been found which mediates the simultaneous triple-lysogenic conversion of enterotoxin A, staphylokinase and beta-lysin. The phages were recovered fro methicillin-resistant strains of S. aureus isolated in Irish hospitals between 1971 and 1988 and from strain PS42-D, which has been used as the propagating strain for the S. aureus typing phage 42D since before 1965. The molecular mechanism of triple conversion mediated by three of these phages was determined by molecular cloning, restriction endonuclease site mapping and hybridization analysis, and compared with the mechanism of beta-lysin and staphylokinase conversion mediated by the serotype F, double-converting phase phi 13. THe genetic determinants mediating expression of enterotoxin A (entA) and staphylokinase (sak) were cloned from the DNA of the triple-converting phage and expression of the cloned determinants detected in Escherichia coli and S. aureus. The entA and sak determinants were closely linked in the phage DNA adjacent to the phage attachment site (attP) in each case and furthermore, the sak determinant of phage phi 13 was also located near its attP. The restriction maps of the entA-, sak- and attP-containing DNA regions of the three triple-converting phages were very similar to each other and to the corresponding sak- and attP- containing DNA region of phage phi 13. Hybridization analysis using a cloned beta-lysin determinant (hlb) and cloned attP-containing DNA fragments as probes demonstrated that beta-lysin conversion mediated by the triple-converting phages and phage phi 13 was caused by insertional inactivation of the chromosomally encoded hlb determinant by orientation-specific integration of phage DNA following lysogenization.
Antimicrobial Cationic Peptides↗
A new methicillin- and gentamicin-resistant Staphylococcus aureus in Dublin: molecular genetic analysis.
In June 1985 two new strains of methicillin- and gentamicin-resistant Staphylococcus aureus (MGRSA) were isolated in a Dublin hospital. Of these, one strain spread rapidly, affecting a total of 65 patients during the following 18 months, and subsequently spread to a second Dublin hospital. Detailed laboratory studies, including plasmid screening, plasmid restriction enzyme digest pattern analysis, hybridisation analysis, location of resistance determinants, and bacteriophage typing with a set of experimental S. aureus typing phages, demonstrated that the "new" MGRSA organisms, termed Phenotype III Dublin isolates, were completely distinct from, and unrelated to, the MGRSA strains responsible for serious nosocomial infections in Dublin hospitals during the decade before June 1985. These Phenotype III isolates were very similar to MGRSA organisms isolated in a Baghdad hospital during 1984. Data from plasmid curing, plasmid transfer and hybridisation experiments indicated that 20% of the Phenotype-III isolates expressed chromosomally encoded, high level resistance to ethidium bromide (MIC 120 micrograms/ml), and that this was possibly due to chromosomal integration of a penicillinase-like plasmid.
Autoradiography↗
Enterotoxin production by Staphylococcus aureus isolates from cases of septicaemia and from healthy carriers.
In a prospective study, 52 Staphylococcus aureus isolates from individual patients with septicaemia and 27 nasal strains from separate, healthy carriers were compared for production of a range of extracellular proteins and toxins. Whereas there was no difference (p greater than 0.05) between septicaemic and nasal isolates with respect to incidence of alpha, beta, gamma and delta haemolysins, toxic shock syndrome toxin-1 or staphylokinase production, the incidence of enterotoxin A, B, and C production was higher among isolates from septicaemia (p less than 0.01). Of the isolates from septicaemia, 33 (63%) produced enterotoxins A, B, C or D alone or in combination. Only three (11%) of the nasal isolates produced a single enterotoxin, enterotoxin D. Of the isolates from septicaemia, 67% were hospital-acquired and greater than 25% of these were endemic, methicillin-resistant (MRSA) strains. All MRSA strains produced either enterotoxin A, or enterotoxin B, or both. These findings suggest a possible role for enterotoxins in the pathogenesis of S. aureus disease other than food poisoning.
Bacterial Toxins↗
Use of strips containing tetracycline hydrochloride or metronidazole for the treatment of advanced periodontal disease.
Strips containing tetracycline hydrochloride or metronidazole 25% in polyhydroxybutyric acid as a biodegradable polymer matrix, showed sustained release in simulated gingival fluid pH 6.6 at 37 degrees C. When evaluated in patients suffering from advanced periodontal disease, the greatest response to therapy was observed with tetracycline hydrochloride strips inserted into periodontal pockets at four-day intervals for 16 days, compared with an untreated control group. A reduction in plaque index, gingival index and pocket depth was observed. A favourable alteration occurred in the microbial flora of treated pockets with an increase in the proportion of cocci and decrease in gram-negative rods, fusiforms and spirochetes. Metronidazole strips or root-planning tended not to be as effective. The clinical improvement produced by each treatment was not maintained when treatment was terminated.
Administration, Topical↗
Molecular studies on interspersed repetitive and unique sequences in the region of the complementation group uncoordinated on the X chromosome of Drosophila melanogaster.
The technique of chromosome walking was used to isolate approximately 60 kb of DNA from the region containing the complementation group uncoordinated of Drosophila melanogaster, located in that part of the X chromosome which spans the euchromatin-heterochromatin junction. The cloned DNA can be divided into two distinct regions. The first contains sequences that are low copy number or unique and are largely conserved between strains. The second region is characterized by units repeated in tandem arrays and is polymorphic within, and between, strains. Each repetitive unit is separated by a member of an abundant sequence family, part of which is homologous to the ribosomal type 1 insertion sequence of D. melanogaster. The molecular organization of the cloned DNA was compared with that of sequences isolated from regions of intercalary heterochromatin and also with genes which have been characterized from more conventional euchromatic regions.
Animals↗
The putative association of alpha haemolytic streptococci with maternal mastitis and neonatal septicaemia.
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Animals↗
Inadequate seizures in ECT.
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Electroconvulsive Therapy↗
Utility of frozen platelets for a platelet antibody assay using flow cytometric analysis.
The immunoreactivity of a PLA1 antibody-containing serum to frozen/thawed platelets prepared by four different procedures was measured to assess the practicality of preparing a platelet reagent that could be easily stored and readily used in an immunofluorescent platelet antibody detection system. These frozen aliquots were analyzed at intervals up to 23 weeks after initial freezing and storage. For analysis, the frozen platelets were thawed, washed, resuspended to 2.5 x 10(5) platelets/mL and incubated with a dilution of fresh autologous serum that lacked platelet antibody or with a similar dilution of frozen human serum containing IgG anti-PLA1 antibody. At each interval, a freshly drawn platelet sample from the same donor was incubated in the same manner and used for comparison. All platelet mixtures were then washed and incubated with fluorescein conjugated goat F (ab')2 antihuman IgG. After repeat washing, each mixture was then analyzed with a flow cytometer for the extent of fluorescent antibody bound to each platelet mixture. Anti-PLA1 antibody reactivity with either the fresh or the frozen/thawed platelets remained stable over the period of analysis, with no significant difference in immunofluorescence with either fresh or frozen platelets as target cells. Platelet recovery following the thawing step ranged from 12% to 36% and was independent of the storage time. These studies suggest that frozen platelets can be readily used as reagents for platelet antibody assays.
Antibodies↗
Platelet antibody detection using frozen pooled human lymphocyte antigen-typed platelets as target cells.
The immunoreactivity of five sera containing either iso-, auto- or allo-antiplatelet antibodies to frozen-thawed human lymphocyte antigen (HLA)-typed pooled platelets was assessed to determine the practicality of using such a platelet preparation in an immunofluorescent platelet antibody system. The platelet reagent was analyzed over an 8-week period after initial freezing and storage. Mixtures of platelets with each serum or dilutions of it were initially incubated for 1 hour, then extensively washed and incubated with fluorescein-conjugated goat F(ab')2 antihuman IgG, A, M. After repeat washing, each mixture was then analyzed using a flow cytometer to determine the relative amount of fluorescent antibody bound. Not only was each of the five sera consistently positive for the presence of an anti-platelet antibody, but the extent of immunoreactivity for each remained relatively stable over the 8-week period of analysis. The results suggest that frozen pooled HLA-typed platelets should be an invaluable reagent for screening serum samples for the presence of antiplatelet antibodies in patients who are thrombocytopenic or who are refractory to platelet transfusion therapy.
Blood Platelets↗
Molecular cloning and characterization of esterase-6, a serine hydrolase of Drosophila.
The Est-6 gene of Drosophila melanogaster was cloned by screening libraries with synthetic oligonucleotides corresponding to tryptic peptides from purified esterase-6 (Est-6) protein. cDNA clones were isolated that hybridized in situ to the site of Est-6 on chromosome 3 at 69A1. Inserts in putative Est-6 cDNA clones were 1.85 kilobases (kb) long, and blot hybridization analysis of electrophoretically fractionated RNA, using a cDNA clone as a probe, revealed two transcripts, of 1.68 and 1.83 kb. The two transcripts showed the same developmental profile as the Est-6 protein. Neither transcript was detected in an Est-6-null line. The cDNA fragment was homologous to a 2.3-kb EcoRI-BamHI fragment in genomic clones, and this region was interrupted by the 8-kb B104 transposable element in the Est-6-null line. Conceptual translation of the cDNA sequence revealed a protein of 548 residues with 19% sequence similarity to acetylcholinesterase from the Torpedo ray.
Amino Acid Sequence↗
Absence of left ventricular dysfunction during acute chagasic myocarditis in the rhesus monkey.
Recent studies suggest that intracellular Trypanosoma cruzi invasion with release of intracellular myocardial antigens during T. cruzi infection is crucial to the pathogenesis of chronic chagasic myocarditis. However, in areas endemic for Chagas' disease, the incidence of clinical acute chagasic myocarditis has been reported to be low among infected individuals, while the incidence of chronic chagasic myocarditis is relatively high. Thus, either acute chagasic myocarditis rarely complicates T. cruzi infection and is not important to the pathogenesis of chronic chagasic myocarditis, or acute chagasic myocarditis rarely impairs left ventricular function and therefore causes no symptoms. To investigate this question we innoculated T. cruzi from a human patient with Chagas' disease into the subconjuntivae of six rhesus monkeys (7.5 X 10(3) parasites each). Parasitemia was monitored and weekly two-dimensional echocardiograms (for determination of end-diastolic and fractional change in area, EDA and FCA) were obtained to quantify global left ventricular function for 10 weeks. Regional left ventricular function was assessed by visual analysis of two-dimensional echocardiograms. Extent of acute myocarditis was established at autopsy. All monkeys had the Romaña sign and detectable parasitemia in the second week. Parasitemia rose in all by the ninth week (mean = 1.8 X 10(5) parasites/ml); four monkeys lost weight (mean = -12%), three died, and three were killed. Two-dimensional echocardiographic EDA and FCA remained unchanged from control to the last study within 12 hr of death (EDA = 2.6 +/- 0.9 to 2.7 +/- 1.0 cm2, FCA = 80 +/- 6.8 to 74 +/- 7.6%, NS). Furthermore, regional left ventricular function remained unchanged throughout the period of study.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Changes in excitability induced by herpes simplex viruses in rat dorsal root ganglion neurons.
The physiological properties of rat sensory neurons infected with herpes simplex type 1 viruses and maintained in cell culture were studied using intracellular recording techniques. Two syncytial (cell fusing) and two nonsyncytial strains of virus were examined; individual strains of virus had different effects on neuronal excitability. The nonsyncytial viruses caused a loss of tetrodotoxin-sensitive low-threshold action potentials and blocked hyperpolarization-activated inward rectification, but did not alter the resting membrane potential, depolarization-activated outward rectification, or render the cells leaky. These effects develop progressively over the period 5-15 hr postinfection. One syncytial strain of virus induced spontaneous electrical activity that appeared to be the result of discrete electrical coupling between sensory neuron processes; as a result, action potential discharge is synchronized in coupled neurons. A second syncytial strain of virus rendered neurons inexcitable; however, in these experiments the input resistance fell to low values, possibly as a result of extensive coupling between sensory neurons. Viral replication in sensory neurons was demonstrable with indirect immunofluorescence using an antibody to herpes simplex viruses and correlated with the onset of virally induced changes in excitability. Virally triggered changes in excitability were blocked by the specific herpes virus antimetabolite acyclovir, suggesting that viral adsorption and penetration are by themselves insufficient to evoke changes in excitability. These results suggest that herpes viruses have selective effects on the excitable mechanisms in sensory neurons that are not simply the result of a general loss of membrane conductances or the disruption of transmembrane ion gradients.
Action Potentials↗
Spontaneous electrical activity induced by herpes virus infection in rat sensory neuron cultures.
Dissociated cultures of rat dorsal root ganglion neurons were infected with a syncytial strain of herpes simplex virus type 1. Over 90% of neurons in infected cultures were spontaneously active and fired action potentials which, on membrane potential hyperpolarization, were replaced by depolarizing events similar to excitatory postsynaptic potentials. Amplitude analysis of these events produced populations described by the sum of several unitary events with Gaussian rather than binomial or Poisson distributions. Such spontaneous activity was blocked by tetrodotoxin but not by low calcium high magnesium solutions containing cadmium. Simultaneous recording from pairs of spontaneously active neurons revealed excitatory connexions between cells. It is suggested that virus-induced fusion of nerve cell processes induces electrical coupling between sensory neurons, and that the resulting electrical network supports spontaneous activity.
Animals↗
Genetic similarity theory: a reply to Mealey and new evidence.
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Adult↗