Biologics in oral medicine: ulcerative disorders.

Inflammatory ulcerative diseases of the oral mucosa are wide ranging but include especially aphthous and aphthous-like ulceration, vesiculobullous disorders and erosive lichen planus (LP). While most patients with these conditions respond to conventional topical and/or systemic immunosuppressive agents, treatment-resistant cases remain challenging. In these, the use of biologics such as tumour necrosis factor alpha (TNF-α) inhibitors or rituximab may be of benefit. This article reviews the use of biologics in ulcerative oral conditions, highlighting potential benefits, adverse effects and principles of use and future developments. TNF-α inhibitors such as infliximab can be effective in inducing resolution in oral aphthous and aphthous-like ulcers and may be an appropriate therapy in those patients in which disease is severe and refractory to, or patients are intolerant of, traditional immunomodulatory regimens. There would also seem support and rationale for use of biologics (mainly rituximab) in pemphigus but not in oral LP or other oral ulcerative conditions.

Biologics in oral medicine: Sjogren syndrome.

Oral Diseases (2012) doi:10.1111/j.1601-0825.2012.01932.x Biologic therapy has a potential to benefit patients with orofacial manifestations of Sjogren syndrome (SS). The most appropriate use of biologics would appear to be in patients with severe or multisystem features of SS, but their use early in the pathogenesis has the potential to prevent disease progression. Tumour necrosis factor-alpha blockade has not proven effective in SS. B-cell depletion using rituximab has been of benefit, mainly in relation to extraglandular features, and to some extent in relation to hyposalivation where there is still residual salivary function. Rituximab is also effective in the treatment of SS-associated (extrasalivary) lymphomas, although the therapeutic response in salivary lymphoma is poorer. Rituximab is given as a single or periodic intravenous infusion. Potential adverse effects exist, notably infusion reactions and infection, and so a full risk/benefit analysis is indicated for prospective patients. This and clinical use is best performed and monitored in conjunction with rheumatologists with appropriate training and experience in biologic therapies. Further studies of rituximab in SS are ongoing, and newer agents under trial include belimumab.

Biologics in oral medicine: oral Crohn's disease and orofacial granulomatosis.

Antitumour necrosis factor (TNF-α) therapy has a potential to benefit patients with oral lesions of Crohn's disease (CD) and patients with orofacial granulomatosis (OFG). The most appropriate use would appear to be in patients with severe or multisystem features, where other available agents have failed or have been associated with adverse effects. TNF-α antagonists (infliximab in particular) have a role in the management of orofacial CD and OFG, but potential adverse effects of TNF-α antagonists include acute infusion reactions, infection and increased risk of malignancy. Thus, a full risk-benefit analysis is indicated, with patient selection, use and subsequent monitoring coordinated with gastroenterologists with appropriate training and experience in biological therapies.

Biologics in oral medicine: principles of use and practical considerations.

Oral Diseases (2012) 18, 525-536 Biologic therapies are relatively innovative treatments aimed at modulating lymphocytes or cytokines. There are currently three broad classes of biologic therapies, tumour necrosis factor-alpha inhibitors, lymphocyte modulators and interleukin inhibitors; all are increasingly used in the treatment of inflammatory immune-mediated conditions, and several have potential applications in oral medicine. Guidelines for their use in licensed indications (e.g. rheumatoid arthritis, psoriasis, inflammatory bowel disease) include recommendations and guidance for patient selection and subsequent monitoring with discussion of potential adverse effects. An understanding of these is important when managing patients receiving biologic therapy for systemic disease, and compliance is essential in any use in oral medicine. Key aspects of current guidance are presented with particular emphasis on their relevance to clinicians working within oral and maxillofacial medicine/pathology/surgery and in specialist practice.

Efficacy of tumour necrosis factor-α antagonists in aphthous ulceration: review of published individual patient data.

BACKGROUND: Severe aphthous ulceration may require systemic immunosuppressive or immunomodulatory therapy, but a small subset of patients remains resistant to or intolerant of these agents. Although use of TNF-α antagonists in aphthous ulceration is increasingly reported, the current evidence base for use is weak and evaluation of individual cases may provide the best available data to support such use. OBJECTIVES: The aim of this study was to review all published data on the use of TNF-α antagonists in patients with severe aphthous ulceration refractory to systemic agents and discusses this in the context of any possible benefits that may guide any future use. METHODS: A comprehensive search on MEDLINE and EMBASE from 1995 to 2010 was performed using pre-defined search terms, with articles included if they met specific criteria. RESULTS: Sixteen cases from individual case reports or small case-series in which use of TNF-α antagonists in aphthous ulceration were identified in which details of previous systemic therapy and use of subsequent adjunctive therapy were available. Agents with reported success in resolving active ulceration and reducing ulcer recurrence were infliximab, etanercept and adalimumab. CONCLUSIONS: Evidence for efficacy of TNF-α antagonists in aphthous ulceration infection is limited. Such data suggest that in patients with severe aphthous ulceration TNF-α antagonists have some efficacy in inducing ulcer resolution and reducing recurrence. These agents may represent an option in severe refractory aphthosis, although in the absence of controlled studies, caution is advocated if use is to be considered.

The effect of oxalate on gluconeogenesis by isolated chicken hepatocytes. Increased sensitivity to inhibition as a result of biotin deficiency.

Addition of varying concentrations of oxalate to isolated chicken hepatocytes reduced gluconeogenesis from lactate in a manner indicating that pyruvate carboxylase was not the rate-limiting step. With hepatocytes from biotin-deficient chicks, sensitivity to inhibition was increased, and was consistent with pyruvate carboxylase being rate-limiting. Administration of biotin to deficient chicks overnight restores sensitivity to oxalate to normal.

Quantitation of DNA from exfoliated colonocytes isolated from human stool surface as a novel noninvasive screening test for colorectal cancer.

The only widely used screening test for early detection of colorectal cancer, the fecal occult blood test, lacks both sensitivity and specificity because it relies upon incidental bleeding rather than the neoplastic process. With the purpose of developing a new noninvasive diagnostic approach, we quantified DNA extracted from cells isolated from the surface of human stools by a novel procedure. Stools collected from 28 healthy individuals, 17 colorectal cancer patients, and 11 colorectal polyp patients were analyzed. A stool DNA index (SDNAI), expressed as DNA amount in nanograms per gram of stool, had a remarkable 4.5-fold difference in mean values between colorectal cancer patients and healthy people of comparable age. SDNAI was 2133 +/- 407 in the cancer group versus 469 +/- 65 in healthy people of the older (> 50 years) age group (P = 0.0005). The difference was independent of tumor location and size. If 700 ng of DNA/g of stool was taken as a cutoff SDNAI value in discrimination between older healthy people and cancer patients, sensitivity and specificity values reached 1.00 and 0.81, respectively. Age dependence of SDNAI was demonstrated by substantially lower SDNAI values (mean, 227 +/- 41) in younger healthy individuals. Polyp patients sometimes displayed elevated SDNAI values, but considerable variation was observed (mean, 1215 +/- 548). These preliminary findings indicate that SDNAI provides a novel, simple, and powerful noninvasive test for colorectal cancer early detection and screening. The fundamental advantage of the SDNAI is that it directly characterizes colonic epithelium involved in carcinogenesis.

Apolipoprotein E and methylenetetrahydrofolate reductase genetic polymorphisms in relation to other risk factors for cardiovascular disease in UK Caucasians and Black South Africans.

Genetic polymorphisms for apolipoprotein E (apo E) and methylenetetrahydrofolate reductase (MTHFR) are believed to modulate risk of coronary heart disease (CHD) acting through regulation of lipid and homocysteine metabolism, respectively. The distributions of apo E and MTHFR alleles in Black South Africans, a population with a low CHD incidence, and UK Caucasians from the Cambridge area, with a higher CHD incidence, were therefore compared. Clinically healthy volunteers (207), including 107 UK Caucasians from the Cambridge area and 100 Black South Africans, participated in the study. Apo E and MTHFR genotypes were determined in all of them. Analyses for serum total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and plasma fibrinogen were carried out in 65 UK Caucasians and 60 Black South Africans. The apo E epsilon4 allele, which is associated with elevated CHD risk, was present in 48% of Black South Africans compared to 20.8% of Caucasians (P < 0.0001); however, both total and LDL cholesterol levels in Black South Africans were 18-32% lower than in Caucasians with similar apo E genotypes. Hyperhomocysteinemia-causing MTHFR 677T variant was detected in only 20% of Black South Africans (no homozygotes) versus 56% of Caucasians with 12% homozygotes (P<0.0001). Our findings suggest that the potentially unfavourable pattern of apo E allele distribution in Black South Africans does not result in increased CHD incidence due to protection by dietary and/or other life style related factors. The exceptionally low frequency of MTHFR mutant homozygotes in this population suggests that this polymorphism should not be regarded as an important CHD risk factor among Black South Africans.

Presence in human urine of a new N-nitroso compound, N-nitrosothiazolidine 4-carboxylic acid.

Urine samples collected in several countries from human subjects showed the presence of a number of N-nitroso compounds not previously identified. By several separative procedures and by comparison with authentic material, the major unknown N-nitroso compound was shown to be N-nitrosothiazolidine 4-carboxylic acid (NTCA). Although its origin in human urine is unknown, thiazolidine 4-carboxylic acid, the easily nitrosatable amine precursor, can be formed by reaction of formaldehyde with cysteine in vivo and in vitro. Thus measuring NTCA excreted in the urine may allow monitoring exposure of human subjects to precursors like formaldehyde and NO-3/NO-2.

Magnetic polyethyleneimine (PEI) microcapsules as retrievable traps for carcinogen electrophiles formed in the gastrointestinal tract.

Semi-permeable magnetic microcapsules containing polyethyleneimine (PEI) have been developed as retrievable carcinogen traps. In vitro, the soluble core PEI and membrane both bound reactive substances of limited aqueous stability, such as from [14C]N-methyl-N-nitrosourea ([14C]NMU), and aqueous stable dyes of molecular weight up to 1000. The core/membrane location ratio of binding was dependent upon membrane characteristics of the microcapsule batch used. Microcapsules administered intragastrically to rats bound up to 0.006% of [14C]dimethylhydrazine ([14C]DMH) and 1.4% of [14C]NMU administered i.p. or intrarectally, respectively. Time-dependency of [14C]DMH binding was consistent with labelling of microcapsules within the small intestine. There were no detectable metabolites from [14C]DMH trapped within the colon, whereas binding of [14C]NMU indicated that microcapsules could bind transient species present within the colon in competition with the faecal bulk. These results indicate that this approach could be used to detect highly unstable and possibly genotoxic substances in situ, hitherto unknown, formed within the intestinal lumen.

Comparison of metabolic effects of vegetables and teas with colorectal proliferation and with tumour development in DMH-treated F344 rats.

The aim of this study was to screen potentially chemopreventive vegetables and teas for their effects as human dietary components for the colorectal epithelium and also to seek biomarkers of preventive efficacy. Groups of F344 rats were adapted to a human basal diet supplemented with vegetables or teas, having known contents of glucosinolates, polyphenols and anti-oxidants. Both inductions and suppressions were found for overall glutathione S-transferase (GST) and quinone reductase activities. The mitotic index (MI) showed a three-fold range between groups, with substantial reductions by black tea, spinach, petit pois and peppers. Changes to PCNA labelling index and proliferation zone were marginal. No correlation was found between colonic and hepatic enzyme activities, nor with glucosinolate intake. Colonic MI was associated with the activity ratio GST(hepatic)/GST(colonic) (r = 0.49, P < 0.002), possibly reflecting a need for direct induction rather than exposure to products of hepatic conjugation.

Insulin and growth hormone act synergistically to stimulate insulin-like growth factor-I production by cultured chicken hepatocytes.

Cultured chicken hepatocytes were used to investigate whether insulin and GH interact to regulate insulin-like growth factor-I (IGF-I) production in vitro. In the first set of experiments hepatocytes were preincubated for 6 h in hormone-free medium, and the effects of various combinations of insulin and GH on IGF-I production over the next 24 h were quantified by radioimmunoassay. Basal IGF-I production was 5.36 pg IGF-I/micrograms DNA and this was increased 1.31 +/- 0.13-fold (mean +/- S.E.M.) by insulin, 1.90 +/- 0.24-fold by GH and 4.46 +/- 0.68-fold by a combination of insulin and GH. These results demonstrate that insulin and GH interact synergistically to stimulate IGF-I production in vitro. The synergism with GH occurred at physiological concentrations of insulin with half-maximal stimulation occurring at an insulin concentration of 6 ng/ml. In hepatocytes which had been exposed to insulin immediately before the start of the experiment, the presence of insulin was no longer required for maximal stimulation of IGF-I production by GH. This in-vitro system will facilitate the study of the molecular basis of the interaction between insulin and GH.

Purification and biological activity of a single charge isomer of pituitary-derived chicken growth hormone.

The chicken pituitary gland contains a number of naturally occurring, developmentally regulated forms of GH which have identical molecular weights but differ in their isoelectric points. In order to characterize their biological properties, each must be separated from non-GH proteins and other forms of GH. Chickens GH (cGH) was separated from other pituitary proteins by immunoaffinity chromatography using an anti-GH monoclonal antibody covalently linked to Sepharose 4B. The cGH eluted from this column as a single peak and migrated as a single band during sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), but showed multiple bands on isoelectric focussing. This material was chromatographed on a high-performance cation exchange column, and separation of charge isomers was monitored by a combination of isoelectric focussing and immunoblotting. Chicken GH eluted from this column in two distinct peaks. The minor peak (cGH P1) contained an isomer with an isoelectric point of 6.86 and the major peak (cGH P2) an isomer with an isoelectric point of 7.52. Each isomer migrated as a single band during isoelectric focussing and SDS-PAGE (Mr = 23,500), and as a single peak during high-performance gel permeation chromatography and reverse-phase high-performance liquid chromatography. Analysis of cGH P2 through 30 cycles in a gas-phase microsequencer gave an amino acid sequence identical to that predicted by translation of the GH complementary DNA nucleotide sequence. This single charge isomer increased the rate of lipolysis in chicken adipose tissue explants by about fourfold and was able to displace 125I-labelled cGH from binding sites in liver membranes with a dissociation constant of about 4 nmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of insulin-like growth factor I production in primary cultures of chicken hepatocytes by chicken growth hormone.

Extracts of conditioned media from primary cultures of chicken hepatocytes stimulated [3H]thymidine incorporation into chick embryo fibroblasts demonstrating that the cells released mitogen(s) into the medium. There was also a simultaneous release of insulin-like growth factor I (IGF-I) immunoreactivity into the medium. Acid chromatography of freeze-dried extracts of conditioned media by high performance gel permeation chromatography demonstrated that IGF-I immunoreactivity eluted in a major peak with a molecular weight of 7500 Da and a minor peak with a molecular weight of 55,000 Da. The release of IGF-I immunoreactivity was increased by pituitary-derived chicken growth hormone (cGH) in a dose-dependent manner with half-maximum stimulation occurring at a cGH concentration of 40 ng/ml and maximum stimulation at cGH concentrations greater than 800 ng/ml. These results demonstrate that cultured chicken hepatocytes produce IGF-I and that this can be stimulated by cGH in vitro.

Magnetic microcapsule exploration in the gastrointestinal cavity of the origins of colorectal cancer-associated DNA-damaging agents in the human diet.

Magnetically recoverable, semipermeable microcapsules have been devised for covalent entrapment of reactive substances in the intestinal cavity to biomonitor potentially DNA-damaging agents and the effects of etiologically important components of the human diet. These microcapsules have been shown to trap five types of agents in vivo, namely, carcinogen electrophiles, nitrosating agents, mutagens/carcinogens having a planar molecular structure, and as-yet unidentified endogenous cross-linking agents and precursors of reactive oxygen species. Substantial alterations in both total metabolites and types of metabolites trapped from [14C]benzo(a)pyrene were found to be caused by increasing (within the human intake range) the dietary levels of beef protein and dietary fiber. The system thus responds to a variety of potentially critical agents and in a manner consistent with epidemiologically important dietary modulators for colorectal carcinogenesis. Work toward recognizing entrapped endogenous agents has also begun.

Magnetic microcapsules as novel biomonitors of cross-linking agents and diet-dependent reactive oxygen species in the human gastrointestinal tract.

Six healthy, scientifically informed human volunteers were given 14C-labeled polyethyleneimine (PEI) microcapsules by mouth. Fecal 14C recovery was inversely related to mean gut transit time (r = -0.66), and the extent of cross-linking between the membrane and core PEI was inversely related to total fecal output (r = -0.81). Cross-linking of PEI microcapsules may be a biomonitor of endogenous cross-linking agents within the human gastrointestinal tract. Extensive loss of [14C]CH3 label occurred from the microcapsules during human transit and in in vitro fermentations with human fecal flora. A mechanism whereby reactive oxygen species could arise in the iron-rich core of these microcapsules, leading to loss of [14C]CH3 label, is proposed.

Occurrence in human urine of new sulphur-containing N-nitrosamino acids N-nitrosothiazolidine 4-carboxylic acid and its 2-methyl derivative, and their formation.

To quantitate endogenous nitrosation reactions in man, the quantity of N-nitrosoproline (NPRO) excreted in the urine after ingestion of proline and/or nitrate was estimated. When this monitoring method (NPRO test) was applied in clinical and field studies, several hitherto unidentified N-nitroso compounds were frequently detected. These were recently identified as sulphur-containing N-nitrosamino acids, N-nitrosothiazolidine 4-carboxylic acid (NTCA), and trans- and cis-isomers of N-nitroso-2-methylthiazolidine 4-carboxylic acid (NMTCA). NTCA and NMTCA were readily formed in vitro following nitrosation at acidic pH of the respective precursor, thiazolidine 4-carboxylic acid (TCA) or of 2-methylthiazolidine 4-carboxylic acid (MTCA). As the latter compounds can be formed by reaction of L-cysteine with formaldehyde or acetaldehyde, respectively, NTCA and NMTCA were also formed by reacting L-cysteine with the respective aldehyde and with nitrite at optimal pH (2.5 for NTCA and 4.5 for NMTCA). Up to 95% of NTCA and NMTCA given orally to fasted rats was recovered as such in urine and faeces within 2 days. Administration of TCA or MTCA, together with nitrite increased the urinary excretion of NTCA and NMTCA, as did co-administration of L-cysteine, nitrite, and the respective aldehyde. NTCA and NMTCA were also detected in the 24-h urine of human volunteers, and smokers tended to excrete higher levels than nonsmokers. Daily excretion levels varied, however, and a diet supplemented with ascorbic acid significantly decreased the total amount of nitrosamino acids. NTCA and NMTCA may occur in human urine as a result of (i) intake of preformed N-nitroso compounds; (ii) intake of thiazolidine 4-carboxylic acid or its 2-methyl derivative and subsequent nitrosation in vivo; (iii) endogenous two-step synthesis by the reaction of L-cysteine with the respective aldehyde and a nitrosating agent. Thus, measurement of NTCA and NMTCA together with NPRO in urine may provide an index for the exposure of human subjects to nitrosamines or their precursors, i.e., nitrosating agents, certain aldehydes, or aldehyde-generating compounds. Our data demonstrate unequivocally that N-nitroso compounds are formed in the human body, as suggested previously by Druckrey. Their relevance to human cancer at specific sites should now be investigated.

Infrared spectroscopic studies on the development of crystallinity in dental zinc phosphate cements.

An infrared spectroscopic study has been made of the development of crystallinity (hopeite) in dental zinc phosphate cements. Crystallization in the bulk of a cement is prevented only by the incorporation, in the liquid, of aluminum which forms complexes with phosphoric acid. The development of surface crystallinity is related to the chemical composition of the cement and the speed of the reaction. No acid phosphates are to be found in the matrix which consists solely of neutral orthophosphates.