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Biomedical subjects

D B Drucker

Publications and source records attributed to D B Drucker.

At least 55 records · Page 3Linked to original sources
PubMed1996

Variations in the susceptibilities of components of the endodontic microflora to biomechanical procedures.

The role of the endodontic microflora in pulpal disease and in endodontic treatment failures is well established. Thus the need for effective microbial control is one of the important justifications for biomechanical procedures. However the efficacy of this stage of treatment is dependent upon the vulnerability of the involved species, which may not be uniform. The aim of this study was to investigate variations in the susceptibilities of members of the root canal microflora to routine biomechanical procedures. Forty-two root canals were investigated microbiologically. Samples were collected before and after instrumentation and the bacterial findings were compared. In 15 cases of 'primary' root canal therapy, despite changes in the population size, no significant change in the species composition of the microflora was observed. However in 27 cases 'secondary' treatment, a decrease in the number of isolations of Peptostreptococcus spp. was found (P = 0.008). When all 42 cases were considered together, significant decreases were found between first and second samples for anaerobes (P = 0.0117) and for Grampositive species (P = 0.008), especially Peptostreptococcus spp. (P = 0.02). It was therefore concluded that certain species are more resistant to the biomechanical procedures than others.

Bacteria↗
PubMed1996

Phospholipid profiles of Clostridium difficile.

Phospholipid molecular species present in 32 isolates of Clostridium difficile were examined by fast atom bombardment-mass spectrometry in negative-ion mode. This revealed major anions consistent with the expected presence of the following phosphatidylglycerol (PG) analogs: PG(31:2), PG(32:1), PG(33:2), PG(33:1), PG(34:2), and PG(34:1). The major phospholipid molecular species are distinct from those of other bacterial groups examined.

Clostridioides difficile↗
PubMed1996

Sleeping position and upper airways bacterial flora: relevance to cot death.

The hypothesis that the prone sleeping position is associated with accumulation of upper airways secretions and increased bacterial growth was investigated in adults. Ten subjects with upper respiratory tract infection lay prone for one hour and then supine for one hour. Nasal swabs after the prone period yielded higher bacterial counts than swabs obtained after the supine period. This result could be relevant to sudden infant death syndrome (SIDS), as infants who sleep in the prone position are at increased risk of SIDS and one theory is that death is caused by toxins produced by bacterial overgrowth in the upper respiratory tract following a viral infection.

Adult↗
PubMed1996

Microbiological and serological investigations of oral lesions in Papillon-Lefèvre syndrome.

Microbiological and serological (enzyme linked immunosorbent assay) investigations were carried out, including karyotyping, on two Asian children with Papillon-Lefèvre syndrome. In case 1, a girl aged four years, the most prevalent putative periodontopathogens were Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia (deciduous dentition) and Bacteroides gracilis, E corrodens and F nucleatum (permanent dentition). In case 2, a boy aged nine years, they were F nucleatum, P intermedia and P loeschii and E corrodens. Serum from case 2 showed a raised specific IgG antibody response to Actinomyces actino-mycetemcomitans serotype b. Thus, a wider range of species than hitherto reported may be associated with Papillon-Lefèvre syndrome, including A actino-mycetemcomitans and F nucleatum.

Actinomyces↗
PubMed1996

Significance of endotoxin in lethal synergy between bacteria associated with sudden infant death syndrome: follow up study.

AIM: To investigate the role of endotoxin in synergy between bacterial toxins associated with sudden infant death syndrome (SIDS). METHODS: Extracellular toxins of 13 isolates of Staphylococcus from SIDS victims and matched healthy infants were tested for lethal toxicity in chick embryos with and without standard endotoxin (used at 1.00 ng/embryo). Endotoxin and toxins from staphylococci were used at dilutions with negligible lethality. RESULTS: Simultaneous injection of non-lethal levels of endotoxin and toxins from 11 of the 13 staphylococcal isolates tested produced lethal toxicity that was 111 to 613% greater than expected by an additive effect alone. This was highly significant and occurred even in the absence of staphylococcal enterotoxins or toxic shock syndrome toxin-1. CONCLUSION: Endotoxin enhancement of staphylococcal toxin lethality could be partly responsible for the clinical outcome in SIDS.

Bacterial Toxins↗
PubMed1995

Cytokines may give insight into mechanisms of death in sudden infant death syndrome.

There are a number of postulated causes of sudden infant death syndrome, including bacterial toxins, defects in thermoregulation and hypersensitivity. This paper formulates the hypothesis that analysis of cytokine profiles in suspected sudden infant death syndrome victims may give an insight into mechanisms of death. These cytokine profiles may also help to identify specific causes of sudden infant death syndrome or indicate that different causes act in concert in individual cases.

Allergens↗
PubMed1995

Polar lipids of Staphylococcus strains analysed by fast atom bombardment mass spectrometry.

This study used fast atom bombardment mass spectrometry (FAB MS) to obtain detailed information on polar lipids of Staphylococcus by examining 23 isolates. Eighteen major anions were found in the range m/z 199-297, consistent with the presence of carboxylate anions. A further 21 major anions were found in the higher mass regions of m/z 609-805, consistent with the presence of phospholipid anions. In Staph. aureus, Staph. epidermidis, Staph. haemolyticus and Staph. hominis, the most intense peaks putatively assigned as carboxylate ions were consistent with presence of C15:0, followed by C17:0 except in the case of Staph. epidermidis. The major phospholipid anions were consistent with the presence of PG(30:0), PG(32:0) and PG(33:0). It is concluded that Staphylococcus has a characteristic polar lipid profile and that qualitative and quantitative differences may be seen between Staph. aureus and Staph. epidermidis.

Carboxylic Acids↗
PubMed1995

Phospholipids of Lactobacillus spp.

Lactobacillus phospholipid molecular species were analyzed by mass spectrometry. Prominent anions were consistent with presence of the phosphatidylglycerols PG(37:2), PG(36:2), PG(35:1), PG(34:1), and PG(33:1). Diglycosyldiacylglycerol molecular species were also observed, although nitrogen-containing phospholipids were absent. An anion of m/z 759 was derived from an apparently novel type of lipid.

Glycolipids↗
PubMed1995

Effects of nicotine on bacterial toxins associated with cot death.

Toxins produced by staphylococci and enterobacteria isolated from the nasopharynx of cases of sudden infant death syndrome (SIDS) have a lethal effect when injected into chick embryos. If the toxins are progressively diluted the lethal effect disappears, but certain combinations of toxins show synergy so that if sublethal doses are mixed a highly lethal effect is produced. In this paper it is shown that nicotine at very low concentrations (less than that produced in man by 0.05 cigarettes) potentiates the lethal action of certain SIDS associated bacterial toxins and markedly potentiates the lethal action of synergistic combinations of bacterial toxins. These results could explain, at least in part, why parental smoking increases the risk of SIDS. They also provide further support for the common bacterial toxin hypothesis of cot death.

Animals↗
PubMed1995

Lethal synergy between toxins of staphylococci and enterobacteria: implications for sudden infant death syndrome.

AIM: To test the hypothesis that lethal synergy occurs between toxin preparations of nasopharyngeal staphylococci and enterobacteria from sudden infant death syndrome (SIDS) victims and matched healthy infants. METHODS: SIDS and matched healthy babies were studied if both staphylococcal and enterobacterial strains were isolated from the nasopharynx. The lethality of toxin preparations from each bacterial isolate (separately and combined) was assessed over a range of dilutions using the chick embryo assay system. RESULTS: Staphylococci and enterobacteria were isolated together from the nasopharynx of seven SIDS babies but from only one normal healthy infant. Enterobacterial toxins were lethal at high dilutions. Staphylococcal toxins were less toxic. Simultaneous testing in the chick assay of staphylococcal and enterobacterial toxins, from each baby, at non-lethal concentrations enhanced lethality levels by 177 to 1011% compared with lethality expected by an additive effect alone. CONCLUSIONS: Synergy occurs between the toxins of nasopharyngeal staphylococci and enterobacteria. This combination of strains is more likely to occur in the nasopharynx of SIDS victims than that of healthy infants.

Case-Control Studies↗
PubMed1994

Nutrient-conditioned flavor preference and acceptance in rats: effects of deprivation state and nonreinforcement.

Rats acquire strong preferences for flavors paired with intragastric (IG) Polycose infusions. The present study investigated the ingestive responses to these flavors when they were no longer reinforced. All rats were first trained to associate a CS+ flavor with IG 32% Polycose and a CS- flavor with IG water during 23 h/day sessions. Experiment 1 examined the effects of deprivation on short-term (4 h/day) CS intakes under nonreinforcement conditions. Food deprivation selectively enhanced CS+ intake whereas water deprivation increased both CS+ and CS- intakes. The results also suggested that extinction training differentially affects CS+ preference and acceptance as measured by relative and absolute intakes. This was confirmed in a second experiment. The rats' absolute intake of the CS+ solution during 4 h/day sessions significantly decreased when it was no longer paired with IG Polycose infusions; yet the rats continued to show a strong preference for the CS+ over the CS- in both 4 h and 23 h/day tests. Experiment 3 examined the effects of extensive long-term extinction training on the CS+ preference. When the alternative was plain water, the CS+ preference extinguished over 12 days. Yet the same rats continued to prefer the CS+ to the CS- during 12 additional extinction days and during 16 extinction days that followed a 1-month rest period. The CS+ preference relative to the CS- was blocked only when the CS+ was paired with food deprivation and the CS- was paired with food repletion. These experiments confirm earlier reports of the resistance of Polycose-conditioned flavor preferences to extinction but also show that flavor acceptance is more susceptible to extinction. Flavor acceptance was not completely extinguished, however, and remained responsive to deprivation state.

Animals↗
PubMed1994

Associations of specific bacteria with some endodontic signs and symptoms.

Although a wide range of bacterial species has been isolated from infected dental root canals it remains necessary to determine whether any particular group of such bacteria is associated with specific endodontic symptoms and clinical signs. In this study 30 root canals were examined microbiologically; of these, 14 were associated with pain, 20 with tenderness to percussion, 23 presented with wet root canals, seven with swelling, five with purulent exudate and four with a sinus. Clinical and microbiological correlation was observed particularly with regard to pain where anaerobes were isolated from 93% of painful canals and only from 53% of painfree canals. The former yielded means of 2.5 anaerobic species and 1.6 facultative species per canal, compared with 1.5 and 2.4 in painfree canals. Prevotella spp. were isolated from 64.2% of painful canals and 12.5% of painless canals (P < 0.01) similarly, peptostreptococci were isolated from 71.4% of painful and 31.3% of painless canals (P < 0.05). It was concluded that a significant association exists between pain and the presence of Prevotella and Peptostreptococcus spp. in dental root canals.

Bacteria, Anaerobic↗
PubMed1994

Antibodies to endotoxin core in sudden infant death syndrome.

To assess the possible role of endotoxaemia in the pathogenesis of sudden infant death syndrome (SIDS), antibodies to endotoxin core (EndoCAb), which have previously been shown to be depressed by systemic endotoxaemia, were measured. IgG and IgM EndoCAb and total serum IgG and IgM were measured in serum samples from 25 children who had died from SIDS and 164 control children under 1 year of age. Twelve (48%) of the 25 children who had died from SIDS had no detectable IgG EndoCAb compared with 28 (17%) of the 164 control children, and this difference was concentrated in children aged less than 3 months. There was no significant difference between the two groups in the percentage of children with no IgM EndoCAb, nor in the total IgG and IgM concentrations. For IgM EndoCAb, the younger children who had died from SIDS had higher concentrations than the controls. These results suggest that, in children who have died from SIDS, due to either unusually early or severe exposure to endotoxin, maternal IgG EndoCAb have been depleted and early IgM EndoCAb triggered.

Aging↗
PubMed1994

Positive and negative associations between bacterial species in dental root canals.

Significant associations have been previously reported between certain pairs of bacterial species isolated from human dental root canals. The aim of this study was to examine microbiologically a more extensive series of cases, with particular reference to obligate anaerobes which accounted for 64% of total isolations. A total of 65 different species was isolated and individual root canals yielded a maximum of eleven bacterial species. Highly significant positive associations (p < 0.001) were found between Peptostreptococcus spp. and Prevotella spp., between Peptostreptococcus spp. and P. melaninogenica, between P. micros and Prevotella spp., P. micros and P. melaninogenica and between Prevotella spp. and Eubacterium spp., all with an ODDS ratio of > 9.0. In contrast, negative and highly significant associations (p < 0.01) were found only between the four species pairs: B. vulgatus/F. necrophorum, P. magnus/Bifidobacterium spp., B. gracilis/F. nucleatum and between B. gracilis/Fusobacterium spp.; all with an ODDS ratio of < 0.5. Some previously published associations were confirmed and some new associations were found, while some negative associations became apparent.

Bacteria, Aerobic↗
PubMed1993

The influence of post-filtration washing on the in vitro assay of Candida albicans adherence to human buccal epithelial cells.

A simple in vitro assay technique was used to determine the effect of post-filtration washing on the adherence of C. albicans (NCPF 3736) to human buccal epithelial cells (BEC). Washing was carried out with a range of volumes of phosphate buffered saline (PBS), viz. 0, 5, 10 and 20 ml, at a standard flow rate. Both the number of C. albicans adherent to BEC and the percentage of BEC with adherent C. albicans were significantly decreased (p < 0.001 for each of these measures) after washing with 5 ml PBS. Further increases in the volume of PBS did not significantly decrease either measure of adherence. These data indicate that only a small volume of PBS, 5 ml, is required to achieve the removal of non-adherent C. albicans from the surface of BEC. The result of the adherence assay is not significantly affected by increasing the volume of PBS used. It is concluded that considerable savings in time may be made through using only a small (5 ml) volume of washing buffer at a standard flow rate.

Adhesiveness↗
PubMed1993

The possible influence of the menstrual cycle on the adherence of Candida albicans to human buccal epithelial cells in vitro.

Although the influence of the menstrual cycle on both vaginal candidosis and Candida albicans adherence to vaginal epithelial cells in vitro has been shown to be significant, similar studies have not been made on oral candidosis and adherence to buccal epithelial cells. The aim of this study was therefore to use an in vitro adherence assay to investigate the possible influence of the menstrual cycle on the adherence of C. albicans to buccal epithelial cells. Epithelial cells were collected from a single, healthy, female volunteer on days 5, 15, 22 and 28 of six menstrual cycles. Adherence of C. albicans was significantly higher to buccal epithelial cells collected on day 5 of the menstrual cycle when compared with days 15, 22 and 28, both in terms of the percentage of buccal epithelial cells with adherent C. albicans and the number of C. albicans adhering per 200 buccal epithelial cells in four out of six menstrual cycles (p < 0.001). This result indicates that hormonal influences should be considered when buccal epithelial cells are used in vitro to assess candidal adherence and may implicate hormonal factors in the aetiology of oral candidosis.

Bacterial Adhesion↗
PubMed1993

Flavor preference produced by intragastric polycose infusions in rats using a concurrent conditioning procedure.

Prior studies demonstrate that nondeprived rats learn to prefer a flavor (the CS+) paired with intragastric (IG) nutrient infusions over another flavor (the CS-) paired with IG water infusions when the flavors are presented on alternate days. The present experiment determined if a nutrient-based preference could be established when both flavors were concurrently available. Adult female rats were fitted with two chronic gastric catheters and were given ad lib access to chow and two flavored solutions (a bitter sucrose octaacetate solution and a sour citric acid solution). Using an automated infusion system, consumption of the CS+ flavor was paired with IG infusions of 32% Polycose, and consumption of the CS- flavor was paired with IG infusions of water. Seven of the eight rats tested developed a strong flavor preference for the CS+ over the CS-; their CS+ preference increased from 53% on day 1 to 95% on day 8. (The remaining animal eventually displayed a 97% CS+ preference after it received one-bottle training with the CS flavors.) During the first several days of training, the rats tended to drink primarily one flavor per day, and consumed primarily one flavor per drinking bout. This provided them with relatively discrete flavor-consequence experiences that presumably facilitated flavor preference conditioning.

Animals↗