Osteolipoma of the buccal mucosa: a case report.

Lipomas are benign mesenchymal neoplasms of soft tissue that can be found commonly in any part of the human body. Their presence in the oral mucosa is uncommon, however, with approximately 4% of the cases occurring in the oral cavity. Oral lipomas are likely to have originated from mature adipose tissue and there are several histological variants of lipomas described, which are identified according to the predominant type of tissue in addition to adipose tissue. A rare lipoma variant, known as an osteolipoma or an ossifying lipoma, may occur; however, little has been written this type of lipoma characterized by a classical lipoma with areas of osseous metaplasia. This paper describes a case of an osteolipoma involving the buccal mucosa of an adult patient.

Oral manifestations as an early clinical sign of acute myeloid leukaemia: a case report.

Leukaemia is the most common malignancy in children and one of the most common malignancies in young adults. Acute myeloid leukaemia is often associated with early oral manifestations. The purpose of this study is to report the case of a 49-year-old male with spontaneous gingival bleeding for over two years with undiagnosed leukaemia. Haematological investigation was instigated and on referral to the Haematology Department at Dunedin Public Hospital, the diagnosis of an acute myeloid leukaemia was confirmed. Since oral lesions can be one of the early events of acute myeloid leukaemia, they may be considered as an important diagnostic indicator for oral health practitioners, and their roles in diagnosing and treating such patients.

Calibre-persistent labial artery: often misdiagnosed as a mucocoele.

The authors present five cases of calibre-persistent labial artery (CPLA) all of which were diagnosed clinically as a labial mucocoele. The purpose of this article is to bring this rarely reported lesion to the attention of clinicians.

Histopathological profile of surgically removed persistent periapical radiolucent lesions of endodontic origin.

AIM: To determine the types of periapical lesions associated with root filled teeth with persistent periapical pathosis that required surgical treatment based on specific inclusion and exclusion criteria. METHODOLOGY: Periapical lesions from a consecutive clinical sample of 100 patients were examined histopathologically to determine a definitive diagnosis. RESULTS: Females were more represented (n = 56), the average age was 46.5 years and there were no age differences between gender or lesion type. A diagnosis of periapical granuloma was the most common finding with a similar number present in females (n = 40) and males (n = 37). A cyst was present in 18% of the cases with a majority of females (n = 12) represented in the sample. Evidence of foreign material, with an appearance consistent with endodontic sealer materials, was seen in 25 periapical granulomas, two cysts and one scar. Two periapical scars were seen, one had a history of apicectomy and amalgam root-end filling while the other was associated with extruded root filling material. CONCLUSIONS: By using defined clinical inclusion and exclusion criteria a predictable clinical diagnosis of a persistent periapical lesion due to endodontic origin can be reliably made. Periapical granulomas and cysts were the most common periapical lesions of endodontic origin associated with persistent periapical pathosis with the overall incidence of periapical cysts similar to previous studies. The presence of endodontic material in a high proportion of periapical lesions suggests a cause-effect association with the inference that clinicians should employ canal preparation techniques that limit apical extrusion of material.

Bite injuries: pathophysiology, forensic analysis, and management.

Bites are serious injuries that constitute 1 percent of all emergency-department visits in the United States of America. Human bite injuries may lead to loss of function, infection, and gross disfigurement, and often are associated with interpersonal and sexual violence, and child abuse. Issues with infection from oral contaminants, tissue damage, and difficult surgical reconstruction make the management of human bite injuries a challenge. The unique nature of teeth and the bite marks they produce are invaluable in forensic pathology. A systematic and detailed evaluation of bite injuries should be performed by a forensic odontologist in order to provide the necessary information for forensic purposes. Management of human bite injuries includes wound debridement, surgery to repair or replace damaged tissue, and long-term antibiotic therapy.

Dental misidentification on the basis of presumed unique features.

Positive identification of skeletal remains by dental comparison depends on the demonstrable concordance between postmortem and antemortem records. However, there is no accepted norm for the number of points of concordance and there are circumstances when a single (or a few) unique features may allow positive identification. We present a recent case in which superficial similarity may have led to misidentification. We argue that misidentification is particularly likely with over-reliance on apparently unique features. The fact that a single inexplicable inconsistency will rule out a positive dental identification is highlighted.

Oral lesions in scurvy.

Scurvy is the nutritional deficiency state associated with lowered levels of ascorbic acid (vitamin C). Lack of ascorbic acid leads to suppression of collagen synthesis and the synthesis of defective collagen among other metabolic derangements. Weakening of vascular walls results in signs and symptoms mimicking other diseases such as bleeding diatheses and deep vein thrombosis. Scurvy is rarely encountered in Western countries where there is a broad community understanding of the importance of nutritional requirements and where foods containing ascorbic acid are readily available. As a result of these factors early diagnosis may be hampered where it is not considered in the differential diagnosis, and consequently, prolonged suffering of the patient. Scurvy is easily treated with high doses of oral ascorbic acid, although recurrences may occur. Education of health care providers in recognizing the signs and symptoms of scurvy therefore cannot be over emphasized, particularly in societies in which nutritional deficiencies are considered uncommon. A case of scurvy presenting primarily with oral manifestations is reported here.

An IS257-derived hybrid promoter directs transcription of a tetA(K) tetracycline resistance gene in the Staphylococcus aureus chromosomal mec region.

Transcription of the tetA(K) tetracycline resistance determinant encoded by an IS257-flanked cointegrated copy of a pT181-like plasmid, located within the chromosomal mec region of a methicillin-resistant Staphylococcus aureus isolate, has been investigated. The results demonstrated that transcription of tetA(K) in this strain is directed by both an IS257-derived hybrid promoter, which is stronger than the native tetA(K) promoter in the autonomous form of pT181, and a complete outwardly directed promoter identified within one end of IS257. Despite lower gene dosage, the chromosomal configuration was shown to afford a higher level of resistance than that mediated by pT181 in an autonomous multicopy state. Furthermore, competition studies revealed that a strain carrying the chromosomal tetA(K) determinant exhibited a higher level of fitness in the presence of tetracycline but not in its absence. This finding suggests that tetracycline has been a selective factor in the emergence of strains carrying a cointegrated pT181-like plasmid in their chromosomes. The results highlight the potential of IS257 to influence the expression of neighboring genes, a property likely to enhance its capacity to mediate advantageous genetic rearrangements.

In vitro resistance of Staphylococcus aureus to thrombin-induced platelet microbicidal protein is associated with alterations in cytoplasmic membrane fluidity.

Platelet microbicidal proteins (PMPs) are small, cationic peptides which possess potent microbicidal activities against common bloodstream pathogens, such as Staphylococcus aureus. We previously showed that S. aureus strains exhibiting resistance to thrombin-induced PMP (tPMP-1) in vitro have an enhanced capacity to cause human and experimental endocarditis (T. Wu, M. R. Yeaman, and A. S. Bayer, Antimicrob. Agents Chemother. 38:729-732, 1994; A. S. Bayer et al., Antimicrob. Agents Chemother. 42:3169-3172, 1998; V. K. Dhawan et al., Infect. Immun. 65:3293-3299, 1997). However, the mechanisms mediating tPMP-1 resistance in S. aureus are not fully delineated. The S. aureus cell membrane appears to be a principal target for the action of tPMP-1. To gain insight into the basis of tPMP-1 resistance, we compared several parameters of membrane structure and function in three tPMP-1-resistant (tPMP-1(r)) strains and their genetically related, tPMP-1-susceptible (tPMP-1(s)) counterpart strains. The tPMP-1(r) strains were derived by three distinct methods: transposon mutagenesis, serial passage in the presence of tPMP-1 in vitro, or carriage of a naturally occurring multiresistance plasmid (pSK1). All tPMP-1(r) strains were found to possess elevated levels of longer-chain, unsaturated membrane lipids, in comparison to their tPMP-1(s) counterparts. This was reflected in corresponding differences in cell membrane fluidity in the strain pairs, with tPMP-1(r) strains exhibiting significantly higher degrees of fluidity as assessed by fluorescence polarization. These data provide further support for the concept that specific alterations in the cytoplasmic membrane of S. aureus strains are associated with tPMP-1 resistance in vitro.

Replication of staphylococcal multiresistance plasmids.

Based on structural and functional properties, three groups of large staphylococcal multiresistance plasmids have been recognized, viz., the pSK1 family, pSK41-like conjugative plasmids, and beta-lactamase-heavy-metal resistance plasmids. Here we describe an analysis of the replication functions of a representative of each of these plasmid groups. The replication initiation genes from the Staphylococcus aureus plasmids pSK1, pSK41, and pI9789::Tn552 were found to be related to each other and to the Staphylococcus xylosus plasmid pSX267 and are also related to rep genes of several plasmids from other gram-positive genera. Nucleotide sequence similarity between pSK1 and pI9789::Tn552 extended beyond their rep genes, encompassing upstream divergently transcribed genes, orf245 and orf256, respectively. Our analyses revealed that genes encoding proteins related to the deduced orf245 product are variously represented, in several types of organization, on plasmids possessing six seemingly evolutionarily distinct types of replication initiation genes and including both theta-mode and rolling-circle replicons. Construction of minireplicons and subsequent functional analysis demonstrated that orf245 is required for the segregational stability of the pSK1 replicon. In contrast, no gene equivalent to orf245 is evident on the conjugative plasmid pSK41, and a minireplicon encoding only the pSK41 rep gene was found to exhibit a segregational stability approaching that of the parent plasmid. Significantly, the results described establish that many of the large multiresistance plasmids that have been identified in clinical staphylococci, which were formerly presumed to be unrelated, actually utilize an evolutionarily related theta-mode replication system.

Oral lesions with a papillary surface texture: clinical and pathological correlations.

Oral mucosal lesions with a papillary surface texture are a heterogenous group of conditions with widely varying clinical behaviour. The aetiology is variable and includes genetic, infective, traumatic or neoplastic processes. A biopsy is required to establish a diagnosis and the microscopic examination must be coordinated with the clinical findings. This paper reviews the clinical and histopathological features of papillary or verruciform lesions.

Plasmid-mediated resistance to thrombin-induced platelet microbicidal protein in staphylococci: role of the qacA locus.

Thrombin-induced platelet microbicidal protein 1 (tPMP-1) is a small, cationic peptide released from rabbit platelets following thrombin stimulation. In vitro resistance to this peptide among strains of Staphylococcus aureus correlates with the survival advantage of such strains at sites of endothelial damage in humans as well as in experimental endovascular infections. The mechanisms involved in the phenotypic resistance of S. aureus to tPMP-1 are not fully delineated. The plasmid-encoded staphylococcal gene qacA mediates multidrug resistance to multiple organic cations via a proton motive force-dependent efflux pump. We studied whether the qacA gene might also confer resistance to cationic tPMP-1. Staphylococcal plasmids encoding qacA were found to confer resistance to tPMP-1 in an otherwise susceptible parental strain. Deletions which removed the region containing the qacA gene in the S. aureus multiresistance plasmid pSK1 abolished tPMP-1 resistance. Resistance to tPMP-1 in the qacA-bearing strains was inoculum independent but peptide concentration dependent, with the level of resistance decreasing at higher peptide concentrations for a given inoculum. There was no apparent cross-resistance in qacA-bearing strains to other endogenous cationic antimicrobial peptides which are structurally distinct from tPMP-1, including human neutrophil defensin 1, protamine, or the staphylococcal lantibiotics pep5 and nisin. These data demonstrate that the staphylococcal multidrug resistance gene qacA also mediates in vitro resistance to cationic tPMP-1.

Nucleotide sequence of the F plasmid leading region.

The entire nucleotide sequence of the first DNA segment of the conjugative F plasmid to enter the recipient cell, the leading region, is described. Analysis of the sequence provides further evidence that products encoded within the 13.2-kb leading region are likely to be expressed and perform functions associated with the transferred strand in the recipient cell.

Verruciform xanthoma and concomitant lichen planus of the oral mucosa. A report of three cases.

Verruciform xanthomas are benign muco-cutaneous lesions of unknown aetiology. They have a papillated surface and histologically they are characterised by the presence of foam cells in connective tissue papillae between elongated parakeratinised epithelial rete ridges. Three cases are reported in which oral mucosal verruciform xanthoma and oral mucosal lichen planus occurred concomitantly.

Focal epithelial hyperplasia in an HIV positive man. An illustrated case and review of the literature.

Focal epithelial hyperplasia (FEH) is a rare but distinctive entity of viral aetiology with characteristic clinical and histopathological features. It is usually seen in children and adolescents of American Indian and Eskimo background; however, it has recently been described in adults who are HIV positive. Suppression of the immune system leaves the individual vulnerable to opportunistic infections. With improved management of immunocompromised patients it is increasingly possible that the general dental practitioner will encounter secondary oral infections such as FEH and must therefore be able to recognize, diagnose and treat these lesions. The following report presents a case of FEH in an HIV-infected man, and is followed by a review of the literature.

Complete nucleotide sequence of pSK41: evolution of staphylococcal conjugative multiresistance plasmids.

The 46.4-kb nucleotide sequence of pSK41, a prototypical multiresistance plasmid from Staphylococcus aureus, has been determined, representing the first completely sequenced conjugative plasmid from a gram-positive organism. Analysis of the sequence has enabled the identification of the probable replication, maintenance, and transfer functions of the plasmid and has provided insights into the evolution of a clinically significant group of plasmids. The basis of deletions commonly associated with pSK41 family plasmids has been investigated, as has the observed insertion site specificity of Tn552-like beta-lactamase transposons within them. Several of the resistance determinants carried by pSK41-like plasmids were found to be located on up to four smaller cointegrated plasmids. pSK41 and related plasmids appear to represent a consolidation of antimicrobial resistance functions, collected by a preexisting conjugative plasmid via transposon insertion and IS257-mediated cointegrative capture of other plasmids.

Mobile elements in the evolution and spread of multiple-drug resistance in staphylococci.

Since the introduction of antimicrobial chemotherapy, staphylococci have shown a remarkable propensity to develop drug resistance. As a result, strains have evolved that are resistant to most classes of clinically useful antimicrobial agents. The emergence of these multiply-drug-resistant strains is primarily due to the capture of pre-existent resistance genes. In combination with plasmids and gene transfer mechanisms, mobile genetic elements have been central to the acquisition and dissemination of this resistance. In particular they have played a significant role in the assembly of drug-resistance gene clusters in these multiply-resistant staphylococci.

A retrospective molecular analysis of gentamicin resistance in Staphylococcus aureus strains from UK hospitals.

The composite transposon Tn4001 and a related chromosomal Tn4001-like element, encode resistance to the aminoglycosides gentamicin, tobramycin and kanamycin (GmTmKmr) in Australian strains of Staphylococcus aureus. Southern hybridisation analysis of GmTmKmr S. aureus strains isolated from various hospitals in the UK between 1975 and 1985 indicated that they predominantly encoded chromosomal copies of Tn4001 or a Tn4001-like element. However, a strain isolated in 1985 was found to carry Tn4001 on a plasmid related to pSK1, the prototypical multiresistance plasmid commonly detected in S. aureus strains from Australian hospitals.