Polyadenylylation helps regulate mRNA decay in Escherichia coli

As part of our genetic analysis of mRNA decay in Escherichia coli K-12, we examined the effect of the pcnB gene [encoding poly(A) polymerase I] on message stability. Eliminating poly(A) polymerase I (delta pcnB) dramatically stabilized the lpp, ompA, and trxA transcripts. The half-lives of individual mRNAs were increased in both a delta pcnB single mutant and a delta pcnB pnp-7 rnb-500 rne-1 multiple mutant. We also found mRNA decay intermediates in delta pcnB mutants that were not detected in control strains. By end-labeling total E. coli RNA with [32P]pCp and T4 RNA ligase and then digesting the RNA with RNase A and T1, we showed that many RNAs in a wild-type strain contained poly(A) tails ranging from 10 nt to > 50 nt long. When polynucleotide phosphorylase, RNase II, and RNase E were absent, the length (> 100 nt) and number (10- to 20-fold) of the poly(A) tails increased. After transcription initiation was stopped with rifampicin, polyadenylylation apparently continued. Deleting the structural gene for poly(A) polymerase I (pcnB) reduced the amount of 3'-terminal poly(A) sequences by > 90%. We propose a model for the role of polyadenylylation in mRNA decay.

Measurement of growth hormone-binding protein in the rat by a ligand immunofunctional assay

We have developed a ligand immunofunctional assay (LIFA) for quantifying the circulating functional GH-binding protein (GHBP) in the rat. This two-site solid-phase assay uses a capture monoclonal antibody (4.3) specific to the hydrophilic C-terminal segment of rat GHBP (rGHBP), saturation of binding with human GH, and a detection system of rabbit antihuman GH polyclonal antibody and peroxidase-conjugated antirabbit immunoglobulin G antibody. Results were compared with Scatchard estimates derived by immuno-precipitation with monoclonal antibody 4.3. This assay was used to determine the GHBP levels in male and female rats and to investigate the diurnal properties and dynamics of GH and GHBP interaction in 15-min blood sampling over a 6-h period. The dynamic range of the rLIFA was 0.15-20.0 nM recombinant rGHBP, with intraassay and interassay coefficients of variation of 10.5% (n = 20) and 12.9% (n = 12), respectively. Serum GHBP levels determined by the rLIFA and those derived from Scatchard estimates were strongly correlated (n = 8; beta = 0.55; r2 = 0.89; P = 0.0005). Male rats had lower GHBP levels (6.5 +/- 0.7 nM; mean +/- SE; n = 14) than female rats (35.4 +/- 2.7 nM; n = 15; P = 0.0001). In the diurnal study, male rats had higher GH peaks (312.5 +/- 121.6 ng/ml; n = 7) than female rats (96.5 +/- 15.4 ng/ml; n = 9; P < 0.0001). In contrast to the pulsatile secretion of GH, GHBP levels in both sexes remained stable and showed no relationship to secretory pulses of GH. However, the GH bursts significantly altered the distribution of the GH-GHBP complex in male rats. By saturation and mass analysis, the greater GH pulsatile secretion in male rats resulted in occupancy of GHBP from less than 5% at nadir to about 80% at secretory peaks, in contrast to the less than 5-15% range of GHBP occupancy in female rats. In male rats, greater than 80% of GH at secretory peaks existed in the free form, whereas in female rats, 16-23% of GH existed in the free form during pulsatile secretion. In summary, the rLIFA shows good correlation to Scatchard analysis using an identical antibody. We conclude that this assay provides a rapid, sensitive, and accurate measurement of the circulating functional GHBP in the rat, and that it facilitates the study of GH and GHBP dynamics under a range of physiological conditions.

Assessment of the need for treatment of postendodontic asymptomatic periapical radiolucencies in bone marrow transplant recipients

Oral screening and treatment of existing oral disease before bone marrow transplantation have been reported to decrease the incidence of infectious complications during bone marrow transplantation. Information about the adverse sequelae of specific preexisting oral diseases during bone marrow transplantation is lacking. The presence of postendodontic periapical radiolucencies may suggest recurrent or latent infection. The purpose of this study was to compare the effect of endodontic treatment with nontreatment of asymptomatic postendodontic periapical radiolucencies on the frequency of infectious oral complications during bone marrow transplantation. The records of 276 patients undergoing bone marrow transplantation examined between July 1988 and June 1991 were reviewed retrospectively. Twenty-three postendodontic periapical radiolucencies were identified in 8 women and 15 men. The mean age of patients was 41 years (range, 25 to 58 years). Fourteen of the lesions were untreated, and nine were treated before bone marrow transplantation. When outcomes of transplant complications were compared, neither increased systemic infection as measured by neutropenic days febrile nor local oral infectious complications were significantly different. These results suggest that nontreatment of asymptomatic postendodontic periapical radiolucencies does not increase the incidence of infectious complications during bone marrow transplantation.

Lingual mandibular sequestration and ulceration

This study analyzed 11 patients who had small sequestra associated with ulceration of the lingual mucosa in the posterior mandibular molar area at the level of the mylohyoid ridge. The patients were adults (mean age, 45.3 years) with complaints of sensitive, occasionally painful lesions that appeared for periods that ranged from 1 week to several months. No abnormalities were evident on periapical radiographs; however, in three cases in which occlusal radiographs were available, small irregular radiopacities contiguous with the cortex were noted. Spontaneous exfoliation or surgical removal of the sequestrum resulted in resolution of the lesion. The possible etiologic factors associated with this apparent clinical-pathologic entity are discussed.

Legume-associated residual cyst

This report describes three unique cases of residual cyst (RC) which were characterized by large legume implants. To determine whether these represented a distinctive RC subset or if implanted materials have general importance in RC pathogenesis, a retrospective comparison of these cases and 37 further RCs with 40 control periapical cysts was performed. The frequency of foreign material implantation and the associated histopathologic features were assessed. No significant differences were noted suggesting that foreign implantations do not have an etiologically significant association with RCs and that the legume-associated RCs represent a unique subgroup. The relationship of the legume-associated RCs to the category of lesions variously termed giant cell hyaline angiopathy, oral pulse granuloma or hyaline ring granuloma is discussed.

Rough hypoplastic amelogenesis imperfecta with follicular hyperplasia

This report documents a unique case of rough hypoplastic amelogenesis imperfecta with apparent anterior oligodontia and multiple anomalies of the associated mesenchymally derived tissues. Multiple unerupted teeth showed hypercementosis, distorted roots with aberrant dentin formation, and marked follicular hyperplasia. The hyperplastic follicles had a complex histopathologic appearance that recapitulated some features of the WHO-type odontogenic fibroma. The features of these teeth, the nature of the associated follicular lesions, and their relationship to the unerupted teeth are discussed.

The base metal alloy question in removable partial dentures--a review of the literature and a survey of alloys in use in Alberta

Base metal alloys have been used for over 60 years to cast removable partial denture frameworks. Among other elements, these alloys principally contain nickel, chromium and cobalt, and may be divided into the nickel-containing and nickel-free alloys. Because of the potential biocompatibility hazard created by these and other elements found in the alloys, this group of materials has come under ever increasing scrutiny in the literature. This paper reviews pertinent literature and reports on the findings of a survey on the base metal alloys used in Alberta for the casting of removable partial denture frameworks.

Influence of biofilms on microbial contamination in dental unit water

Water from dental units (DU), used for cooling and clearing the field of dental operations, is frequently contaminated by microorganisms. Retrograde spread of oral microbes into DU tubuing, contaminated plumbing systems and endogenous DU contamination have been implicated. This study investigated the contribution of DU tubing to this contamination in 11 randomly selected DU. The times required, under standardized conditions, for DU bacterial levels to decrease in response to the flushing caused by DU operation, or increase in response to stagnation caused by shutting down the DU, were measured. The DU tubing was then removed and similarly manipulated. The results showed similar bacterial levels and populations in the DU and their corresponding tubes. Sixteen control samples taken from the connecting plumbing system at distant locations, after periods of stagnation which result in DU bacterial contamination, were negative. This suggests the plumbing, in our system, is not an important factor. Thus, DU can endogenously contaminate the water passing through them; their tubes have the potential to generate similar magnitudes of bacterial contamination to that determined from intact DU. Scanning electron microscopy of the tube lumens showed a biofilm, characterized by microorganisms embedded in an amorphous matrix in all cases. This biofilm could act as a reservoir to facilitate rapid recontamination. Further analysis of the data indicates there could be other contributing factors.

Malignant neuroendocrine tumor presenting in the mandible

The carotid body, jugulotympanic, vagal, and laryngeal paragangliomas are the most common paragangliomas respectively within the head and neck, although unusual examples in other sites have been described. Among these are several references in the literature to a mandibular or "alveolar body" paraganglioma, even though such an entity does not appear to have been adequately documented. This report describes a case which presented as an extensive osteoblastic tumor involving the mandible and which radiographically appeared as a typical osteosarcoma. However, the immunohistochemical and electron microscopic features were of a neuroendocrine tumor and the histologic pattern suggested a paraganglioma. The tumor was nonfunctional and an extensive search failed to reveal any further lesions. Eight months after resection of the lesion, metastatic deposits appeared within the left iliac crest and lumbar vertebra. The origin of this tumor is discussed.

Oral cancer and precancer

Oral carcinoma can be regarded as a largely preventable disease. Early recognition should be an attainable goal for most patients undergoing regular dental recall appointments. An understanding of the risk factors and of the characteristics of precancerous lesions can serve to heighten clinical sensitivity to oral SCC. Biopsies should be performed in all cases where the possibility of SCC exists; alternatively, patients should be referred to appropriate specialists for further evaluation.

Candidal infection in oral lichen planus

The prevalence of candidal infection in lichen planus (LP) and its possible association with ulceration were independently examined in two archived series of 108 and 77 cases derived from two separate populations. To ensure that similar material was being compared, each case was histopathologically reassessed and confirmed as LP or reclassified as nonspecific lichenoid stomatitis (NSLS), lichenoid dysplasia (LD), or other (O). Three further sections, cut at 25 microns intervals, were stained with periodic acid-Schiff reagent for the identification of intraepithelial candidal pseudohyphae. As control specimens, 61 normal and 59 hyperkeratotic mucosal samples were similarly processed and examined. Candidal infection was found in 17.4% and 16.4% of ulcerated and nonulcerated LP cases, respectively, and in 40.0% and 16.7% of ulcerated and nonulcerated NSLS cases, respectively. One case of LD was infected. Each control series contained one infected case. The results indicate that candidal infection occurs more readily in LP and NSLS, with no apparent association with ulceration in LP. The comparatively marked increase in the infection prevalence of ulcerated NSLS cannot be statistically confirmed, and its significance remains uncertain.

[Fecal sIgS and lysozyme excretion in breast feeding and formula feeding]

The bioavailability of sIgA and lysozyme from human milk was investigated in a total of 41 infants by radial immunodiffusion and by the Micrococcus lysodeicticus method, respectively. In four different pools of human milk used for balance studies the sIgA concentrations ranged between 2,200 and 17,850 mg/l. The lysozyme concentration varied from 64.5 to 283.5 mg/l. On human milk feeding the excretion of sIgA in 19 infants was 3,200 (0-8,200) mg per litre and 9.7 (0-131) mg lysozyme per litre, respectively. Corresponding values on formula feeding in 22 infants were 1030 (0-6400) and 2.6 (0-9) mg/l. Fecal sIgA excretion was significantly higher on human milk than on formula feeding. Balances of sIgA and lysozyme intake and excretion as performed in 9 infants revealed a less than 1% fecal excretion of both the protective substances. In vitro digestion of raw human milk with pepsin at pH 2 and 3 resulted in a rapid disappearance of immunologically reactive sIgA within 30 minutes after starting the incubation, while no changes in sIgA content were detectable at pH 4. Lysozyme proved to be resistant against peptic digestion. Tryptic digestion at pH 8 did not result in a decrease of human milk sIgA within 120 minutes of incubation at 37 degrees C while under analogous conditions lysozyme concentration approached to 0. These results point at the full bioavailability of both sIgA and lysozyme from human milk. The differing resistance of these protective substances against pepsin and trypsin is apparently adapted to physiological particularities of the digestive tract in early infancy.

Salmonella enteritidis phage type 4 infection of broiler chickens: a hazard to public health

The pericardial fluids and contents of caeca and spleens from 81 broiler chickens that had been condemmed at processing factories because of macroscopic pericarditis were examined for Salmonella species. 47 (58%) of these chickens yielded S enteritidis phage type (PT) 4. Viable counts of the organism in fluids from 6 of the most severely affected hearts ranged from 10(4) to 10(7) colony-forming units/ml. S enteridis PT4 was also isolated from 8 of 20 fresh chilled chickens on retail sale. No other serotype of Salmonella or phage type of S enteritidis was cultured either from the chickens with pericarditis or from the fresh chilled chicken.

Rhabdomyosarcoma of the oral and paraoral region

Oral rhabdomyosarcoma (RMS) was studied by analysis of eight such cases which presented over a 25-year period. Rhabdomyosarcoma was the fourth most common oral sarcoma (7.5%) from this period after osteosarcoma (32%), fibrosarcoma (19%), and chondrosarcoma (9%). In patients younger than 20 years, RMS was the second most common sarcoma (six cases) after osteosarcoma (ten cases). Combined analysis with 113 further cases documented in the literature showed the majority of cases (71.2%) were embryonal. The alveolar subtype was considered a distant second in frequency (12.3%) even though the pleomorphic subtype was apparently more common (16.4%). However, the pleomorphic cases were diagnosed before histologic criteria were established to discern this entity from other pleomorphic sarcomas and this data is probably unreliable. Site predilections were found for the soft palate, maxillary sinus and alveolus, posterior mandibular region, cheek and lip and possibly tongue. The gingiva and floor of mouth were uncommon sites. There was a predilection for occurrence in the first two decades with a decline in the third decade. Documentation of recent cases treated with a multidisciplinary approach indicated that lesions in the oral soft tissues have a good prognosis; 17 of 21 such cases showed no evidence of disease after a mean follow-up period of 7.2 years (SD = 4.4). In contrast, four of five cases in the posterior mandible resulted in death after a mean period of 1.1 years (SD = 0.3).

The causation of oral precancer and cancer

Most cases of oral cancer result from the action of exogenic carcinogenic agents, some of which act synergistically in producing their effects. The evidence implicating tobacco and alcohol abuse is overwhelming and cannot be refuted. Other clearly identifiable aetiological agents include betel nut chewing and excessive exposure to sunlight. While there is increasing evidence of a viral causation, this is not yet clearly established. Similarly, the role of Candida albicans remains uncertain. Lichen planus and discoid lupus erythematosus may constitute important predisposing conditions, but the documentation remains inadequate and inconclusive, as does that implicating electrogalvanism. Tertiary syphilis is no longer considered a significant factor in oral cancer. Sideropenic dysphagia and haemoglobin and serum iron deficiencies may be of importance in the development of oral carcinoma, particularly in elderly women with no history of tobacco and alcohol abuse. The roles of poor oral hygiene and sharp edges of teeth and dentures have probably been overemphasized in the past.

Are postmortem studies of glossal candidal infection useful? An experimental study

Autopsy studies have suggested that candidal pseudohyphae may be found in dorsal glossal epithelium in 38% to 42% of cases. Candidal yeast forms, and occasionally free pseudohyphae, are found as oral commensals in about 44% of the population. This study examined the possible distorting influence in autopsy studies that could be caused by postmortem hyphal transformation of candidal yeast forms followed by saprophytic infestation. Candida albicans yeast forms were topically applied to the middorsal glossal mucosa of five healthy pigs, immediately after killing. Biopsy specimens from this mucosa were subsequently maintained, in vitro, for periods of 12 and 24 hours in humid conditions at different temperature regression rates chosen to approximate those of the oral cavity after death. Biopsy specimens subjected to a temperature regression of 35 degrees C (oral temperature) to 23 degrees C (room temperature) over 11 hours showed infestation of epithelium by pseudohyphae in all cases. Biopsy specimens subjected to a similar temperature regression over 5 hours showed infestation in two of five cases. Control biopsy specimens showed that there was no candidal infection at the time of killing. The results indicate that in vitro saprophytic candidal infestation is possible in the time intervals and the declining oral temperatures preceding autopsy. It suggests that postmortem saprophytic candidal infestation may distort results from autopsy studies that do not anticipate this problem.

In vitro generated human monoclonal trinitrophenyl-specific B cell lines. Evidence that human and murine anti-trinitrophenyl monoclonal antibodies cross-react with Escherichia coli beta-galactosidase

Stable human antigen-specific monoclonal B cell lines were established without prior in vivo immunization. This was accomplished by expanding the anti-trinitrophenyl (TNP) B cells in vitro with the antigen TNP-Brucella abortus and then immortalizing them with Epstein-Barr virus. Five anti-TNP clones were selected by sequential limiting dilution. All five anti-TNP clones secreted IgM kappa antibodies. When tested against a panel of self and environmental antigens, all five anti-TNP clones exhibited cross-reactivity with an Escherichia coli-derived beta-galactosidase. To determine whether this was a more general phenomenon, a panel of murine monoclonals were tested and found to bind to beta-galactosidase. It is therefore possible that human and murine anti-TNP beta cell responses reflect reactivity against an environmental antigen, namely an epitope present on E. coli-derived beta-galactosidase. This approach of expanding human antigen-specific B cells by antigen stimulation in vitro, with a T-independent hapten-carrier conjugate before Epstein-Barr virus transformation, may prove useful in the development of human monoclonals for therapeutic purposes.

In vitro generated human monoclonal trinitrophenyl-specific B cell lines. Evidence that human and murine anti-trinitrophenyl monoclonal antibodies cross-react with Escherichia coli beta-galactosidase

Stable human antigen-specific monoclonal B cell lines were established without prior in vivo immunization. This was accomplished by expanding the anti-trinitrophenyl (TNP) B cells in vitro with the antigen TNP-Brucella abortus and then immortalizing them with Epstein-Barr virus. Five anti-TNP clones were selected by sequential limiting dilution. All five anti-TNP clones secreted IgM kappa antibodies. When tested against a panel of self and environmental antigens, all five anti-TNP clones exhibited cross-reactivity with an Escherichia coli-derived beta-galactosidase. To determine whether this was a more general phenomenon, a panel of murine monoclonals were tested and found to bind to beta-galactosidase. It is therefore possible that human and murine anti-TNP beta cell responses reflect reactivity against an environmental antigen, namely an epitope present on E. coli-derived beta-galactosidase. This approach of expanding human antigen-specific B cells by antigen stimulation in vitro, with a T-independent hapten-carrier conjugate before Epstein-Barr virus transformation, may prove useful in the development of human monoclonals for therapeutic purposes.

Candidal infection of the tongue with nonspecific inflammation of the palate

A retrospective study of ten patients with median rhomboid glossitis (MRG) revealed the presence of a nonspecific inflammatory reaction of varying degrees of severity in the overlying palatal mucosa. Clinical records and photographs indicated that the palatal reactions physically approximated the underlying glossal lesions, suggesting a relationship between these entities. The nature of the relationship is uncertain, but it may involve a localized infection of the palatal mucosa by Candida species, from the MRG. Alternatively, irritation by soluble, possibly Candida-related factors from the MRG that are applied repeatedly to the palatal mucosa during swallowing may be responsible.