Methyl salicylate and (-)-(1R,5S)-myrtenal are plant-derived repellents for black bean aphid,Aphis fabae Scop. (Homoptera: Aphididae).

Methyl salicylate and (-)-(1R,5S)-myrtenal stimulate specific olfactory cells in the primary rhinaria on the sixth and fifth antennal segments, respectively, of the black bean aphid.Aphis fabae. In behavioral studies employing a linear track olfactometer, both compounds were repellent toA.

High prevalence of Helicobacter pylori metronidazole resistance in migrants to east London: relation with previous nitroimidazole exposure and gastroduodenal disease.

A high prevalence of metronidazole resistance in Helicobacter pylori is reported in developing countries. This study examined whether migrants referred for diagnostic gastroscopy at a United Kingdom centre (n = 54), had a higher prevalence of metronidazole resistance than subjects born in the United Kingdom attending endoscopy (n = 46). Records of nitroimidazole treatment prescribed in the United Kingdom was obtained in 83 patients to find out if there was an association between H pylori metronidazole resistance and previous ingestion of either metronidazole or tinidazole.

Production of hydrolytic enzymes by oral isolates of Eikenella corrodens.

Eikenella corrodens isolates from periodontally healthy subjects and adult periodontitis patients were compared for their ability to produce a range of potential virulence factors. All were positive for proline aminopeptidase, thiol-dependent haemolysin and esterase activities. Low or negative activities were found against casein, phospholipid, lipid, collagen, aminophosphate, phosphate under acid or alkaline conditions, and eleven other amino acid substrates tested.

Conservation of the cytotoxin-associated (cagA) gene of Helicobacter pylori and investigation of association with vacuolating-cytotoxin activity and gastroduodenal disease.

Polymerase chain reaction (PCR) amplification and DNA hybridization analyses were used to test for the presence of the cytotoxin-associated (cagA) gene in 108 strains of Helicobacter pylori. Fifty-two geographically diverse strains of known vacuolating cytotoxin activity, and 56 recent UK clinical isolates from patients with duodenal ulceration (n = 28) and from healthy individuals who were endoscopically normal (n = 28) were studied. Overall, cagA was detected by PCR in 74 (69%) strains and DNA hybridization provided evidence of gene homologues in a further eight strains.

Prevalence of Eikenella corrodens and Actinobacillus actinomycetemcomitans in the dental plaque of dogs.

The prevalence and populations of Eikenella corrodens, Actinobacillus actinomycetemcomitans and black pigmented anaerobic bacilli were determined in three samples of supragingival plaque from each of 30 healthy dogs. E corrodens was present in 62 per cent of the dogs and 43.7 per cent of the individual plaque samples but none of the dogs yielded A actinomycetemcomitans.

Comparison of urease gene primer sequences for PCR-based amplification assays in identifying the gastric pathogen Helicobacter pylori.

Different genomic DNA samples and primer sequences were evaluated in urease (ure) gene-based PCR assays for rapid identification of Helicobacter pylori. Purified DNA and heated (boiled) cell lysates of bacterial cultures from gastric biopsies were tested with three primer sets for unique internal ureA, ureA+B and ureC sequences. The heated-lysates of H.

Activities of potential therapeutic and prophylactic antibiotics against blood culture isolates of viridans group streptococci from neutropenic patients receiving ciprofloxacin.

All 47 sequential blood culture isolates of viridans group streptococci obtained from febrile neutropenic patients receiving quinolone prophylaxis were susceptible to vancomycin, teicoplanin, and imipenem. Resistance to benzylpenicillin (MIC for 50% of isolates [MIC50], 0.125 microgram/ml) and ceftazidime (MIC50, 4 micrograms/ml) was common.

Species of alpha-hemolytic streptococci possessing a C-polysaccharide phosphorylcholine-containing antigen.

An enzyme-linked immunosorbent assay technique was used to detect and quantify C-polysaccharide-like antigen in strains of alpha-hemolytic streptococci classified into species by following the latest taxonomic recommendations. C-polysaccharide-like antigen is found only in Streptococcus oralis, S. mitis, and S.

Does HIV cause AIDS? A review.

It would require a detailed knowledge of virology, molecular biology, epidemiology, clinical medicine and politics, to appropriately compare and contrast the hypotheses on the causes of AIDS. The purpose of this review was not to do that, but to inform colleagues that alternative etiologies for AIDS have been considered. No doubt, this healthy questioning will continue until it has been demonstrated--via controlled studies of high-risk groups (both HIV positive and negative), matched for all other characteristics--that only those individuals with HIV positivity actually develop AIDS.

A comparison between commercial kits and conventional methods for enumeration of salivary mutans streptococci and lactobacilli.

Mutans streptococci (ms) and lactobacilli levels were determined by conventional and commercial dip-slide methods in three groups of young subjects, aged 5-6 years (93 subjects), 12-13 years (78 subjects) and 18-20 years (81 subjects). Using the same paraffin-stimulated saliva samples, ms and lactobacilli were estimated by conventional viable counts on modified mitis-salivarius agar (MSB) and Rogosa agar plates, and by inoculation of Dentocult SM and Dentocult LB dip-slides (Orion Diagnostica, Finland). The salivary ms and lactobacilli counts obtained from conventional agar plates were significantly correlated (P < 0.

A 1992 update on hepatitis B vaccination.

Surveillance studies of people at high risk for hepatitis B, combined with almost 10 years of experience with the vaccine, have allowed cost effective vaccination programs to be devised. It would make good sense to incorporate the hepatitis B vaccination into the standard childhood immunization protocols. Present teenagers, who will not benefit from such a program, would be well advised to be vaccinated.

Comparative in-vitro activity of azithromycin, macrolides (erythromycin, clarithromycin and spiramycin) and streptogramin RP 59500 against oral organisms.

The in-vitro activities of azithromycin, clarithromycin, spiramycin and RP 59500 were compared with erythromycin against a wide range of oral organisms which have been implicated in oral infections and/or endocarditis (clindamycin was included for oral streptococci). All compounds tested showed good activity against many of these organisms, although some variation was observed with different species. Clarithromycin was the most active of the antibiotics tested against Gram-positive anaerobes, including Actinomyces spp.

Concerns regarding infection control recommendations for dental practice.

It goes without saying that the members of any professional group are more likely to modify their behavior if they are provided with logical, rational reasons to enact the suggested change. In the mid 1980s, health care providers, including dental personnel, were advised to adopt universal precautions and to alter their infection control habits with minimal justification, apart from the general unease and paranoia surrounding AIDS. Therefore, it is understandable that some practitioners would react with scepticism to the idea that their traditional infection control techniques were less than adequate, while others would overwhelmingly embrace the new recommendations in the misguided belief that personal, patient, staff and family safety would be enhanced.

Oral microbiology: current concepts in the microbiology of dental caries and periodontal disease.

The microbial flora of the mouth is highly complex, containing a wide variety of bacterial species. The most common types of oral disease, dental caries and periodontal disease, are both related to dental plaque and seem to occur when the normal balance between the microorganisms and the host is disturbed in some way. Dental caries is usually associated with increased numbers of mutans streptococci and lactobacilli at the sites of disease; estimation of salivary levels of these organisms may be useful for assessing caries risk in patients and for monitoring their response to preventive measures.