Multiple hormone-inducible enhancers as mediators of differential transcription.

Sets of genes under a common regulatory control in a given cell type are often differentially transcribed. The possibility that this differential transcription can be modulated by the number or strength of cis-acting regulatory sequences associated with a given gene was tested by using the glucocorticoid-responsive enhancer element associated with the mouse mammary tumor virus promoter. Results indicate that differential levels of hormone-inducible gene expression can be modulated in an additive way by the number of glucocorticoid-responsive enhancers associated with this promoter. Realization of these effects shows little preference for position of the additional elements with respect to the promoter. When sequences that bind the glucocorticoid receptor in vitro with somewhat lower affinity than the enhancer were tested, these additive effects were not detected. The results support that differential transcription of genes subject to a common regulatory control can be mediated, at least in part, by the number or strength of their associated cis-acting regulatory sequences.

Blood pressure and blood lipids among vegetarian, semivegetarian, and nonvegetarian African Americans.

Blood pressure (BP) and serum lipids were compared among three dietary groups of Seventh-day Adventist (SDA) African-American adults: vegetarians (VEGs: no consumption of animal flesh, n = 66), semivegetarians (SEMIVEGs: one to three servings of animal flesh per week, n = 56), and nonvegetarians (NONVEGs: daily consumption of animal flesh, n = 45). VEGs had a lower mean waist-to-hip ratio (WHR) and lower dietary intakes of protein, saturated fat, and cholesterol compared with the NONVEGs. Only 16% of the VEGs were confirmed to be hypertensive compared with 35.7% of the SEMIVEGs and 31.1% of the NONVEGs. Independent of differences in WHR, the VEGs had significantly lower concentrations of serum total cholesterol (STC), LDL-C, triglycerides, STC/HDL-C, and LDL-C/HDL-C than the NONVEGs. The SEMIVEGs had lipid values intermediate to the VEG and NONVEG groups. Among African-American SDAs, a vegetarian diet is associated with lower cardiovascular disease risk factors than is an omnivorous diet.

A comparison of two methods for identifying surgical site infections following orthopaedic surgery.

Many infection control practitioners (ICPs) dedicate a significant amount of time and resources to surveillance of surgical site infections (SSIs). Alternative surveillance methods need to be explored to reflect the changes to the healthcare system and the increasing economic constraints placed on infection control units. This study was undertaken to compare two methods of identifying SSIs in orthopaedic surgery. Surveillance data collected routinely by ICPs was compared with data obtained from the International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) coding in the medical record. Concordant results between the two methods were obtained. The use of ICD-9-CM coding, as stored in hospital patient administration system databases, has the ability to enhance routine surgical site surveillance programmes. These systems can be used as the basis for screening large data sets for SSIs and identifying where SSIs resulted in patient re-admission. A reduction in the duplication of data and time spent by the ICP on the collection of information for surveillance purposes can be achieved.

In vitro antibacterial activity of enoxacin (CI-919).

Antibacterial activity of enoxacin was evaluated against more than 3,700 clinical isolates using the agar-dilution method and an inoculum of 10(4)-10(5) cells per site. For comparison other antibiotics appropriate for each species were also included. For most enterobacteria and for Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa, the MIC90 of enoxacin was below 2 mg/l. Serratia marcescens was more resistant; the MIC90 being 4 mg/ml. Enoxacin also showed high activity against Campylobacter jejuni and Neisseria gonorrhoeae. Streptococci were comparatively resistant, 32 mg/l to 64 mg/l of the compound being required to inhibit 90% of strains.

In vitro formation of short RNA polymerase II transcripts that terminate within the HIV-1 and HIV-2 promoter-proximal downstream regions.

Trans-activation of HIV-1 transcription by the viral regulatory protein Tat has been proposed recently to overcome a block to RNA polymerase II elongation in vivo imposed by 5'-untranslated leader sequences. Interestingly, however, only full-length transcripts, rather than prematurely terminated HIV RNAs, are synthesized in most cell-free transcription extracts. Here, we describe an in vitro system in which induction of a highly efficient RNA polymerase II termination or cotranscriptional RNA processing event creates short HIV RNAs with 3' ends that map to a region immediately downstream of the HIV-1 or HIV-2 promoters. Termination in vitro is sequence dependent, generating short HIV-1 RNAs of 58-61 nucleotides that resemble in vivo transcripts observed in the absence of Tat, and a distinct, longer transcript of approximately 125-130 nucleotides from the HIV-2 promoter. Deletion of promoter-proximal HIV-2 downstream sequences results in the loss of a discrete RNA but also fails to restore wild-type transcription, indicating that termination actually is specified at the promoter and occurs at a site positioned by one or more elements located immediately upstream of the 3' end of the short RNAs. Experiments with recombinant HIV-2 promoters and nucleoside analogs indicate that this event involves a concerted interaction between the promoter and orientation-dependent leader sequences and that RNA secondary structure formation may also be required. These data provide direct evidence for abbreviated HIV transcripts and an in vitro approach to understanding the roles of cellular and viral regulatory proteins that mediate this process at the HIV promoters.

In vitro activity of seventeen antimicrobial agents against Gardnerella vaginalis.

The in vitro activity of 17 antimicrobial agents was tested against 25 clinical isolates of Gardnerella vaginalis. Minimum inhibitory concentrations were determined by agar dilution. The isolates were sensitive to penicillin, ampicillin, ticarcillin, piperacillin, cephalothin, cefoxitin, cefotaxime, cefoperazone, N-formimidoyl-thienamycin, chloramphenicol, clindamycin and erythromycin. MIC90 for the beta-lactam antibiotics ranged from 0.12 mg/l for penicillin to 2 mg/l for ticarcillin. Cefoperazone was the most active cephalosporin, inhibiting all isolates at 1.0 mg/l. N-formimidoylthienamycin was the most active of the newer beta-lactam compounds inhibiting all isolates with a concentration of 0.5 mg/l. Clindamycin and erythromycin were highly active, inhibiting all isolates at 0.6 mg/l. Susceptibility to tetracycline, gentamicin, metronidazole and tinidazole varied between strains. All isolates were resistant to rosoxacin. The hydroxy-metabolites of metronidazole and tinidazole were more active than the parent compounds, inhibiting all isolates.

Contamination of parenteral nutrition solutions not a hazard with additions made at ward level.

Pre-mixed amino acid and dextrose solutions used for parenteral nutrition had additions made to them at a ward level by medical officers. Samples of the solutions of the study group and a control group were taken at six hours and at the end of the infusion time and were analysed microbiologically for growth of microorganisms. No organism was isolated from either group. We conclude that making additions to pre-mixed amino acid/dextrose solutions at the ward level does not constitute a microbiological hazard for the patient.

Transcriptional repression of a hormone-responsive promoter.

The activity of the mouse mammary tumor virus promoter was assessed in various sequence contexts with a transient transfection assay in which promoter activity was determined by way of expression of a linked gene encoding chloramphenicol acetyltransferase, as well as by direct analysis of RNA transcripts. The results indicate that the proviral long terminal repeat contains a negative transcriptional control element in addition to the glucocorticoid-responsive transcriptional enhancer that has been described previously. The negative element is able to function in both orientations and, at least to some extent, at multiple positions with respect to the regulated transcription unit. The effects on gene expression cannot be explained by alterations in transfection efficiency. The element has been localized to a 91 base pair fragment located immediately 5' of binding sites for the glucocorticoid receptor protein that have been defined in vitro. The role of the negative element may be to repress the inherent activity of the proviral promoter in the absence of glucocorticoids, resulting in an increased ratio of gene expression in the presence and absence of hormone.

Blood pressure differences in older black and white long-term vegetarians and nonvegetarians.

The vegetarian diet has been associated with lower blood pressure (BP) in elderly white Americans. This study was undertaken to determine whether or not long-term adherence (at least 5 years) to a plant-based diet is similarly related to lower BP in older black Americans, a group exhibiting significant risk for hypertension (HT). Anthropometric characteristics, nutrient intake, and resting systolic and diastolic BP were measured in older black vegetarians (n = 27, age = 69.3 +/- 1.7 years), black nonvegetarians (n = 37, age = 65.4 +/- 1.2 years), white vegetarians (n = 85, age = 66.7 +/- 1.0 years), and white nonvegetarians (n = 54, age = 65.2 +/- 0.9 years). Older black vegetarians were significantly leaner and exhibited lower average systolic BP (131.4/76.8 mm Hg) and less hypertension than the black omnivores (141.6/76.2 mm Hg), but had significantly higher average BP than either dietary group of older white adults (vegetarians: 120.9/66.7 mm Hg; nonvegetarians: 122.8/67.6 mm Hg). These data suggest that long-term adherence to a vegetarian diet by older black Americans may afford some protection against hypertension, but in comparison to older white adults, does not completely offset their apparently greater susceptibility to untoward elevation of BP.

The urban mosquitoes of Suva, Fiji: seasonal incidence and evaluation of environmental sanitation and ULV spraying for their control.

Larval surveys and oviposition traps were used to monitor urban mosquito populations in two adjacent transects in Suva, Fiji between May 1978 and August 1979. Populations of Aedes aegypti and Ae. pseudoscutellaris fluctuated seasonally with changes in rainfall, the latter species being most prevalent throughout the year. Populations of these two species were highest between December and July and lowest between August and October. Larval populations of Culex quinquefasciatus did not show a seasonal variation and larval populations of Cx. annulirostris were too low for any conclusions to be made. All species were found breeding most often in miscellaneous containers, with tyres, plant containers and flower vases also being important sources for Ae. aegypti breeding. Through environmental sanitation the Breteau Index for all species was reduced by 88%; Premise Index by 72% and the Container Index by 83%, when compared to a control area. ULV applied malathion was effective in temporarily reducing Ae. pseudoscutellaris populations from 50--100%. Effects on Ae. aegypti were inconclusive. It is concluded that through enforcement of the existing laws and strict monthly surveillance during the periods of highest seasonal density, urban Aedes and Culex populations can be maintained at an acceptable level.

A mouse mammary tumor virus promoter element near the transcription initiation site.

Transcription from the promoter of mouse mammary tumor virus is subject to both positive and negative control by cellular factors, and proviral promoter elements that mediate a basal level of transcription must in some way respond to these cellular regulatory signals. Several such elements, including a TATA box, a region containing three octamer-related sequences, and a binding site for nuclear factor 1, have been previously defined. Additional promoter mutations have allowed a fourth basal promoter element to be identified near the transcription initiation site between +2 and +10. Sequence alterations within this element affect transcription both in vivo and in vitro. Gel electrophoresis mobility shift and DNase I footprinting assays define a nuclear protein, termed initiation site-binding protein, that specifically recognizes this region of the promoter. Optimal levels of transcription from the mouse mammary tumor virus promoter require initiation site-binding protein, as demonstrated by a correlation between protein affinity and transcriptional activity and by specific inhibition of transcription in vitro by an oligonucleotide capable of titrating the protein from transcriptionally active fractions.

A national collaborative study of resistance to antimicrobial agents in Haemophilus influenzae in Australian hospitals. The Australian Group for Antimicrobial Resistance (AGAR).

An Australia-wide survey of the prevalence of resistance to antimicrobial agents among Haemophilus influenzae was conducted on clinically significant isolates collected between July 1988 and September 1990. Laboratories from the capital cities of each Australian state and territory participated. Nine hundred and seventy clinical isolates were examined for beta-lactamase production and the MICs of ampicillin, coamoxiclav, chloramphenicol, cefaclor, ceftriaxone, cefotaxime, tetracycline, rifampicin, trimethoprim, sulphamethoxazole and co-trimoxazole were determined using the NCCLS agar dilution method with Haemophilus Test Medium. A smaller number of isolates were tested against penicillin V, penicillin G, ciprofloxacin, piperacillin and erythromycin in addition. The proportion of beta-lactamase producing strains was higher among invasive strains (21.6%) than non-invasive strains (14.2%) and varies considerably between states. The highest prevalence of ampicillin resistance was found in invasive strains from Canberra (40.8%), the lowest in non-invasive strains from Adelaide (5.1%). Paradoxically, in non-invasive strains, although beta-lactamase production was less common, resistance to other antimicrobials was commoner than in invasive strains and also varied between states.

In-vitro effects of vancomycin, rifampicin, and fusidic acid, alone and in combination, against methicillin-resistant Staphylococcus aureus.

Minimal inhibitory and minimal bactericidal concentrations were determined for eighteen methicillin-resistant Staphylococcus aureus isolates, the majority also resistant to gentamicin, obtained from the blood of bacteraemic patients. Fifty per cent of organisms had a greater than four-fold difference in M.I.C. and M.B.C. for vancomycin, 83% for rifampicin, and 89% for fusidic acid. In-vitro effects of two-drug combinations of vancomycin, rifampicin, and fusidic acid demonstrated neither synergy nor antagonism when measured by a checkerboard dilution technique. The relevance of these findings to choice of therapy of serious infection due to methicillin-gentamicin resistant Staph. aureus is yet to be determined.

Sequence organization and molecular cloning of mouse mammary tumor virus DNA endogenous to C57BL/6 mice.

The sequence organization of mouse mammary tumor virus DNA endogenous to the C57BL/6 inbred mouse strain was characterized by Southern blot analysis, utilizing probes specific for particular regions of the mouse mammary tumor virus provirus and by molecular cloning of endogenous mouse mammary tumor virus DNA. The genome of C57BL/6 mice contains three apparently intact, endogenous proviral units; two of these units comprise the Mtv-8 (unit II) and Mtv-9 (unit III) genetic loci that are also present in the DNA of BALB/c mice. The third unit is defined by EcoRI restriction fragments of 10.0 and 8.4 kilobases that contain the 5' and 3' portions of the provirus, respectively. This unit, termed unit XI and encoded by the genetic locus Mtv-17, has not been previously recognized in C57BL/6 DNA, but it can be clearly distinguished from the proviral units at Mtv-8 and Mtv-9 by Southern blot analysis under appropriate conditions. The proviral unit at Mtv-17 is not present in BALB/c DNA. DNAs comprising the entire Mtv-8 locus and the 3' portions of Mtv-9 and Mtv-17 were cloned. Analysis of the cloned DNA revealed no obvious deletions or rearrangements that would render proviral DNA defective; however, these endogenous genes are normally not transcriptionally active.

The emergence of erythromycin resistance in Streptococcus pyogenes in Fremantle, Western Australia.

Erythromycin resistance in Streptococcus pyogenes is unusual except in Japan. Since January 1, 1985, a dramatic increase has occurred in the prevalence of erythromycin-resistant Strept. pyogenes infections in the outpatients who have presented to Fremantle Hospital, Western Australia. In 1985, 1% of isolates of Strept. pyogenes was erythromycin-resistant. This had risen to 9.1% of isolates in 1986 and to 17.6% of isolates in 1987. Several M- and T-types of Strept. pyogenes were involved. Treatment failure now can be expected when erythromycin is prescribed for the treatment of common infections in outpatients at this hospital. Laboratories that use disc methods of antimicrobial susceptibility testing may not detect erythromycin resistance in these organisms.

Functional elements of the steroid hormone-responsive promoter of mouse mammary tumor virus.

Transcription from the promoter of mouse mammary tumor virus is subject to induction by several classes of steroid hormones as well as to repression by a negative regulatory element present in the long terminal repeats of proviral DNA. In order to characterize the functional elements of the promoter that in some way must respond to these regulatory signals, a number of promoter mutations were constructed, including a set of linker-scanning mutations across the entire promoter region. Analysis of these mutated promoters with a transient-transfection assay defined at least three mutation-sensitive promoter elements that are required for both basal and hormone-induced transcription. One mutation-sensitive region contains a TATA element located at approximately position -30 with respect to the start of transcription. A second mutation-sensitive region contains two 10-base-pair direct repeats located between positions -60 and -38, within which are embedded three copies of octamer-related sequences; complete disruption of this region of the promoter leads to a more severe decrease in transcription than do any of the linker-scanning mutations, suggesting that the repeated sequences may be at least partially functionally redundant. Gel electrophoresis mobility shift assays were used to demonstrate specific binding of a nuclear protein to this region of the promoter. A third mutation-sensitive region contains a binding site for nuclear factor 1 (NF-1) located between positions -77 and -63. Site-directed mutations in the NF-1-binding site which increase the apparent affinity of NF-1 for the promoter in vitro do not decrease the hormone dependence of transcription, suggesting that transcriptional activation mediated by steroid hormone-receptor complexes cannot be explained by facilitation or stabilization of the interaction of promoter sequences with NF-1 and consistent with the idea that binding of NF-1 is not rate determining in transcription from the mouse mammary tumor virus promoter. None of the promoter mutations functionally separates basal from glucocorticoid-induced transcription, suggesting that hormone induction does not make the promoter independent of any of the DNA-binding factors required for its basal activity.