Trial Forge Guidance 4: a guideline for reporting the results of randomised Studies Within A Trial (SWATs)

BACKGROUND

Evidence to support decisions on trial processes is minimal. One way to generate this evidence is to use a Study Within A Trial (SWAT) to test trial processes or explore methodological uncertainties. SWAT evidence relies on replication to ensure sufficient power and broad applicability of findings. Prompt reporting is therefore essential; however, SWAT publications are often the first to be abandoned in the face of other time pressures. Reporting guidance for embedded methodology trials does exist but is not widely used. We sought therefore to build on these guidelines to develop a straightforward, concise reporting standard, which remains adherent to the CONSORT guideline.

METHODS

An iterative process was used to develop the guideline. This included initial meetings with key stakeholders, development of an initial guideline, pilot testing of draft guidelines, further iteration and pilot testing, and finalisation of the guideline.

RESULTS

We developed a reporting guideline applicable to randomised SWATs, including replications of previous evaluations. The guideline follows the Consolidated Standards for Reporting Trials (CONSORT) statement and provides example text to ensure ease and clarity of reporting across all domains.

CONCLUSIONS

The SWAT reporting guideline will aid authors, reviewers, and journal editors to produce and review clear, structured reports of randomised SWATs, whilst also adhering to the CONSORT guideline.

TRIAL REGISTRATION

EQUATOR Network - Guidelines Under Development ( https://www.equator-network.org/library/reporting-guidelines-under-development/reporting-guidelines-under-development-for-clinical-trials/#SWAT ). Registered on 25 March 2021.

Biological therapies and management of oral mucosal disease

Biologic drugs are drugs made by living organisms and the term is usually limited to monoclonal antibodies or receptors targeting specific cytokines or cells that have been developed in recent decades. These drugs have had an enormous impact on the management of cancers, including head and neck cancers, and immune-mediated inflammatory conditions, for example, rheumatoid arthritis and inflammatory bowel disease. General dental practitioners will routinely be managing patients who are on these medications for a wide range of systemic conditions. These drugs also have a limited role in the management of immune-mediated oral mucosal disease. In this article, we will introduce the range of biological agents and their systemic indications and then elaborate on their use in oral mucosal disease and the disadvantages associated with their use.

Smoking, tooth loss and oral hygiene practices have significant and site-specific impacts on the microbiome of oral mucosal surfaces: a cross-sectional study

We investigated bacterial colonisation patterns of healthy mucosa (buccal, tongue, palate and floor of mouth) in a cohort of adults in order to determine how smoking, tooth loss, plaque levels and oral hygiene practices impacted on mucosal colonisation. A total of 322 swabs were recovered from 256 participants, of whom 46% were current smokers. We analysed colonization by sequencing the V1-V3 regions of the 16S rRNA gene. Palate and tongue microbiomes generally exhibited greater biodiversity than buccal and floor of mouth. Although Neisseria, Lautropia and Haemophilus spp. showed reduced abundance in smokers, buccal mucosa specifically showed a significant increase in Prevotella spp., whereas tongue and floor of mouth tended towards increased abundance of Streptococcus spp. Unexpectedly, tooth brushing frequency had a greater impact on mucosal community structure than plaque levels. Tooth loss was associated with significant reductions in mucosal biodiversity and had site-specific impacts, with buccal communities showing increased abundance of periodontitis-associated species and Rothia mucilaginosa, whereas tongue communities exhibited increased abundance of several streptococcal OTUs and reduced abundance of Haemophilus spp. This study highlights the complex relationship between mucosal colonisation and host factors, highlighting the need for careful consideration of these factors in mucosal microbiome studies.

Influence of site and smoking on malignant transformation in the oral cavity: Is the microbiome the missing link?

The tongue and floor of the mouth are high-risk sites for oral squamous cell carcinoma (OSCC), while smoking is its most significant risk factor. Recently, questions have been raised as to the role of the oral microbiome in OSCC because of a wealth of evidence demonstrating that the microbiome of OSCC differs from that of healthy mucosa. However, oral site and smoking also have a significant impact on oral microbial communities, and to date, the role these factors play in influencing the dysbiotic microbial communities of OSCC and precursor lesions has not been considered. This review aims to examine the influence of site and smoking on the oral microbiome and, in turn, whether these microbiome changes could be involved in oral carcinogenesis.

Classification of cytological samples from oral potentially malignant lesions through Raman spectroscopy: A pilot study

The potential of Raman microspectroscopy of exfoliated cells has been demonstrated for oral cancer diagnosis. In this study, brush biopsies were collected from the buccal mucosa/tongue of healthy donors (n = 31) and from oral mucosal dysplastic lesions (n = 31 patients). Raman spectra were acquired and subjected to partial least squares-discriminant analysis (PLS-DA). The patient samples could be differentiated from healthy donor samples with 96% sensitivity and 95% specificity. Furthermore, PLS-DA models were developed based on cytopathological and histopathological assessment. Low and high grade dysplasia could be discriminated with 64% sensitivity and 65% specificity based on cytopathological assessment, while 81% sensitivity and 86% specificity could be achieved when histopathological assessment was within six months of the brush biopsy sampling. Therefore, this explorative study has successfully demonstrated that Raman spectroscopy may have a role in monitoring patients with dysplasia and may reduce the need for multiple biopsies.

Raman spectral cytopathology for cancer diagnostic applications

Raman spectroscopy can provide a rapid, label-free, nondestructive measurement of the chemical fingerprint of a sample and has shown potential for cancer screening and diagnosis. Here we report a protocol for Raman microspectroscopic analysis of different exfoliative cytology samples (cervical, oral and lung), covering sample preparation, spectral acquisition, preprocessing and data analysis. The protocol takes 2 h 20 min for sample preparation, measurement and data preprocessing and up to 8 h for a complete analysis. A key feature of the protocol is that it uses the same sample preparation procedure as commonly used in diagnostic cytology laboratories (i.e., liquid-based cytology on glass slides), ensuring compatibility with clinical workflows. Our protocol also covers methods to correct for the spectral contribution of glass and sample pretreatment methods to remove contaminants (such as blood and mucus) that can obscure spectral features in the exfoliated cells and lead to variability. The protocol establishes a standardized clinical routine allowing the collection of highly reproducible data for Raman spectral cytopathology for cancer diagnostic applications for cervical and lung cancer and for monitoring suspicious lesions for oral cancer.

Biomedical applications of vibrational spectroscopy: Oral cancer diagnostics

Vibrational spectroscopy, based on either infrared absorption or Raman scattering, has attracted increasing attention for biomedical applications. Proof of concept explorations for diagnosis of oral potentially malignant disorders and cancer are reviewed, and recent advances critically appraised. Specific examples of applications of Raman microspectroscopy for analysis of histological, cytological and saliva samples are presented for illustrative purposes, and the future prospects, ultimately for routine, chairside in vivo screening are discussed.

A pilot study for early detection of oral premalignant diseases using oral cytology and Raman micro-spectroscopy: Assessment of confounding factors

This study demonstrates the efficacy of Raman micro-spectroscopy of oral cytological samples for differentiating dysplastic, potentially malignant lesions from those of normal, healthy donors. Cells were collected using brush biopsy from healthy donors (n = 20) and patients attending a Dysplasia Clinic (n = 20). Donors were sampled at four different sites (buccal mucosa, tongue, alveolus, gingiva), to ensure matched normal sites for all lesions, while patient samples were taken from clinically evident, histologically verified dysplastic lesions. Spectra were acquired from the nucleus and cytoplasm of individual cells of all samples and subjected to partial least squares-discriminant analysis. Discriminative sensitivities of 94% and 86% and specificity of 85% were achieved for the cytoplasm and nucleus, respectively, largely based on lipidic contributions of dysplastic cells. Alveolar/gingival samples were differentiated from tongue/buccal samples, indicating that anatomical site is potentially a confounding factor, while age, gender, smoking and alcohol consumption were confirmed not to be.

Raman microspectroscopic study for the detection of oral field cancerisation using brush biopsy samples

Field cancerisation (FC) is potentially an underlying cause of poor treatment outcomes of oral squamous cell carcinoma (OSCC). To explore the phenomenon using Raman microspectroscopy, brush biopsies from the buccal mucosa, tongue, gingiva and alveolus of healthy donors (n = 40) and from potentially malignant lesions (PML) of Dysplasia Clinic patients (n = 40) were examined. Contralateral normal samples (n = 38) were also collected from the patients. Raman spectra were acquired from the nucleus and cytoplasm of each cell, and subjected to partial least squares-discriminant analysis (PLS-DA). High discriminatory accuracy for donor and PML samples was achieved for both cytopalmic and nuclear data sets. Notably, contralateral normal (patient) samples were also accurately discriminated from donor samples and contralateral normal samples from patients with multiple lesions showed a similar spectral profile to PML samples, strongly indicating a FC effect. These findings support the potential of Raman microspectroscopy as a screening tool for PML using oral exfoliated cells.

Human disease/clinical medical sciences in dentistry: Current state and future development of undergraduate assessments in the UK and Ireland

INTRODUCTION

The United Kingdom and Ireland teachers of Human Disease/Clinical Medical Science for Dentistry (HD/CMSD) group continue to work together and most recently collaborated to review current and future assessments.

MATERIALS AND METHODS

The first part of the review of assessments in HD/CMSD took place at a face-to-face meeting with presentations from delegates on assessments in their home institutions. The second and larger part comprised an online survey where all eighteen schools in the UK and Ireland participated.

RESULTS

All schools had some element of formative assessment, and the majority had a stand-alone summative assessment at the end of the HD/CMSD teaching block. Most schools had a written paper and practical elements to their assessments, most commonly a combination of a multiple-choice type question combined with an objective structured clinical examination (OSCE). There was a trend towards the use of single best answer (SBA) questions and a willingness amongst participants to share a question bank. All schools incorporated elements of HD/CMSD in their final examinations.

DISCUSSION AND CONCLUSION

This collaboration promoted the sharing of developments in assessment for HD/CMSD and demonstrated a willingness to cooperate between institutions. Assessment in HD/CMSD in the UK and Ireland continues to be refined by those responsible for its content and delivery, and assessment methods are progressing following evidence-based best practice.

Human Disease/Clinical Medical Sciences in Dentistry: Current state and future directions of undergraduate teaching in the UK and Ireland

In March 2017, a group of teachers of human disease/clinical medical science (HD/CMSD) representing the majority of schools from around the UK and Republic of Ireland met to discuss the current state of teaching of human disease and also to discuss how the delivery of this theme might evolve to inform improved healthcare. This study outlines how the original teaching in medicine and surgery to dental undergraduate students has developed into the theme of HD/CMSD reflecting changing needs as well as guidance from the regulators, and how different dental schools have developed their approaches to reach their current state. Each school was also asked to share a strengths, weakness, opportunities and threats (SWOT) analysis of their programme and to outline how they thought their HD/CMSD programme may develop. The school representatives who coordinate the delivery and assessment of HD/CMSD in the undergraduate curriculum have extensive insight in this area and are well-placed to shape the HD/CMSD development for the future.

Liquid chromatography/mass spectrometry based detection and semi-quantitative analysis of INSL5 in human and murine tissues

RATIONALE

Insulin-like peptide 5 (INSL5) is a hormone produced by enteroendocrine L-cells in the colon that has recently been implicated in the control of metabolic homeostasis. However, research into its physiology has been hindered by the reported unreliability of commercially available immunoassays and additional detection assays would benefit this emerging field.

METHODS

Peptides from purified murine L-cells and homogenates from both human and mouse colonic tissues were extracted by precipitating larger proteins with acetonitrile. Untargeted liquid chromatography/tandem mass spectrometry (LC/MS/MS) analyses, followed by database searching, were used to detect and identify various INSL5 gene derived peptides and characterise their precise sequence. A similar approach was developed to quantify INSL5 levels in primary intestinal culture supernatants after purification and concentration by solid-phase extraction.

RESULTS

Mass spectral analysis of purified enteroendocrine cells and tissue homogenates identified the exact sequence of A and B chains of INSL5 endogenously expressed in L-cells. Differences in the endogenously processed peptide and the Swissprot database entry were observed for murine INSL5, whereas the human sequence matched previous predictions from heterologous expression experiments. INSL5 was detected in the supernatant of human and mouse primary colonic cultures and concentrations increased after treatment with a known L-cell stimulus.

CONCLUSIONS

The first LC/MS/MS-based method capable of the detection and semi-quantitative analysis of endogenous INSL5 using MS-based techniques has been demonstrated. The methodology will enable the identification of stimulants for INSL5 secretion from murine and human primary colonic epithelial cultures.

The Microbiome of Potentially Malignant Oral Leukoplakia Exhibits Enrichment for Fusobacterium, Leptotrichia, Campylobacter, and Rothia Species

Oral leukoplakia presents as a white patch on the oral mucosa and is recognized as having significant malignant potential. Although colonization of these patches with Candida albicans is common, little is known about the bacterial microbiota of these patches. In the current study we analyzed the microbiome of oral leukoplakia in 36 patients compared to healthy mucosal tissue from the same patients and healthy control subjects to determine if specific microbial enrichments could be identified early in the malignant process that could play a role in the progression of the disease. This was carried out by sequence analysis of the V1–V2 region of the bacterial 16S rRNA gene using the Illumina MiSeq. Oral leukoplakia exhibited increased abundance of Fusobacteria and reduced levels of Firmicutes (Metastats P < 0.01). Candida colonization was also more prevalent in leukoplakia patients relative to healthy controls (P = 0.025). Bacterial colonization patterns on oral leukoplakia were highly variable and five distinct bacterial clusters were discerned. These clusters exhibited co-occurrence of Fusobacterium, Leptotrichia, and Campylobacter species (Pearson P < 0.01), which is strikingly similar to the microbial co-occurrence patterns observed on colorectal cancers (Warren et al., 2013). Increased abundance of the acetaldehydogenic microorganism Rothia mucilaginosa was also apparent on oral leukoplakias from lingual sites (P 0.0012). Severe dysplasia was associated with elevated levels of Leptotrichia spp. and Campylobacter concisus (P < 0.05). Oral leukoplakia exhibits an altered microbiota that has similarities to the microbiome of colorectal cancer.

The microbiome of oral leukoplakia shows enrichment in Fusobacteria and Rothia species

The current study was carried out to determine if changes in the oral microbiome were associated with oral leukoplakia. Swabs of oral leukoplakias were taken from 36 patients. Contralateral normal tissue was also swabbed. Swabs from 35 control patients without symptoms of leukoplakia were also taken. DNA was extracted and the V1V2 region of the 16s rRNA gene was sequenced using the Illumina MiSeq and analysed using the Mothur software package.

The structure of oral mucosal communities was most affected by smoking and the location of the site (AMOVA p < 0.01). Analysis of the constituents of these communities using LEfSe showed that Fusobacterium sp. and Leptotrichia sp. were enriched on leukoplakia sites. Patients with leukoplakia also showed enrichment for Rothia mucilaginosa and Campylobacter sp. Quantitative RT-PCR also showed that leukoplakias from lingual sites were more likely to be colonised by Candida sp. Analysis of these enrichments identified specific co-localisation patterns (Pearson correlation P <0.01) including Leptotrichia sp., Prevotella sp. and Campylobacter concisus; F. nucleatum, Alloprevotella tannerae and C. gracilis, amongst others.

Fusobacteria have been implicated in the progression of colorectal carcinoma and further studies are now required to determine if these microorganisms are linked to the development of OSCC.

Circumorificial plasmacytosis/plasma cell orificial mucositis: a case series and a review of the literature

Circumorificial plasmacytosis is a rare plasma cell proliferative disorder of the orificial mucous membranes. The etiology is unknown, and there are no reported effective treatments to date. We report three cases of idiopathic circumorificial plasmacytosis with varying clinical presentations and responses to treatment, including a first reported case of resolution with adalimumab therapy.

Ebola virus disease: review and implications for dentistry in Ireland

The current Ebola outbreak in West Africa is a global health emergency with implications for all healthcare professionals. This article will review the clinical features, transmission and oral manifestations of Ebola virus infection, and discuss the implications of the current outbreak for dental practices in Ireland. Guidance for managing suspected cases and contacts is also provided.

CONCLUSIONS

Although Ebola is an alarming disease with a very high mortality rate, it is extremely unlikely that the dental team will encounter a new presentation of Ebola or that it will pose a significant transmission risk. The dental team should be aware of the Health Protection Surveillance Centre (HPSC) Algorithm for Ebola Virus Disease Risk Assessment, and it should be followed as necessary. It is advised to defer dental treatment for 21 days after possible exposure to the Ebola virus.

Cold atmospheric pressure plasma and decontamination. Can it contribute to preventing hospital-acquired infections?

Healthcare-associated infections (HCAIs) affect ∼4.5 million patients in Europe alone annually. With the ever-increasing number of 'multi-resistant' micro-organisms, alternative and more effective methods of environmental decontamination are being sought as an important component of infection prevention and control. One of these is the use of cold atmospheric pressure plasma (CAPP) systems with clinical applications in healthcare facilities. CAPPs have been shown to demonstrate antimicrobial, antifungal and antiviral properties and have been adopted for other uses in clinical medicine over the past decade. CAPPs vary in their physical and chemical nature depending on the plasma-generating mechanism (e.g. plasma jet, dielectric barrier discharge, etc.). CAPP systems produce a 'cocktail' of species including positive and negative ions, reactive atoms and molecules (e.g. atomic oxygen, ozone, superoxide and oxides of nitrogen), intense electric fields, and ultraviolet radiation (UV). The effects of these ions have been studied on micro-organisms, skin, blood, and DNA; thus, a range of possible applications of CAPPs has been identified, including surface decontamination, wound healing, biofilm removal, and even cancer therapy. Here we evaluate plasma devices, their applications, mode of action and their potential role specifically in combating HCAIs on clinical surfaces.

Oral hairy leukoplakia in healthy, immunocompetent individuals

Oral hairy leukoplakia (OHL), while typically associated with HIV infection and immunosuppression, is rarely seen in HIV negative immunocompetent individuals. We report on two cases of OHL in immunocompetent patients.

Air and surface contamination patterns of meticillin-resistant Staphylococcus aureus on eight acute hospital wards

BACKGROUND

Meticillin-resistant Staphylococcus aureus (MRSA) can be recovered from hospital air and from environmental surfaces. This poses a potential risk of transmission to patients.

AIM

To investigate associations between MRSA isolates recovered from air and environmental surfaces with those from patients when undertaking extensive patient and environmental sampling.

METHODS

This was a prospective observational study of patients and their environment in eight wards of a 700-bed tertiary care hospital during 2010 and 2011. Sampling of patients, air and surfaces was carried out on all ward bays, with more extended environmental sampling in ward high-dependency bays and at particular times of the day. The genetic relatedness of isolates was determined by DNA microarray profiling and spa typing.

FINDINGS

MRSA was recovered from 30/706 (4.3%) patients and from 19/132 (14.4%) air samples. On 9/132 (6.8%) occasions both patient and air samples yielded MRSA. In 32 high-dependency bays, MRSA was recovered from 12/161 (7.4%) patients, 8/32 (25%) air samples, and 21/644 (3.3%) environmental surface samples. On 10/132 (7.6%) occasions, MRSA was isolated from air in the absence of MRSA-positive patients. Patient demographic data combined with spa typing and DNA microarray profiling revealed four likely transmission clusters, where patient and environmental isolates were deemed to be very closely related.

CONCLUSION

Air sampling yielded MRSA on frequent occasions, especially in high-dependency bays. Environmental and air sampling combined with patient demographic data, spa typing and DNA microarray profiling indicated the presence of clusters that were not otherwise apparent.

Deprivation as an outcome determinant in emergency medical admissions

BACKGROUND

Deprivation in the general population predicts mortality. We have investigated its relevance to an acute medical admission, using a database of all emergency admissions to St James' Hospital, Dublin, over a 10-year period (2002-11).

METHODS

All emergency admissions, based on geocoding of residence, were allocated to a Small Area Health Research Unit division, with a corresponding deprivation index. We then examined this index as a univariate (unadjusted) and independent (adjusted) predictor of 30-day in-hospital mortality.

RESULTS

The 30-day in-hospital mortality, over the 10-year period, was higher for those in the upper half of the deprivation distribution (9.6 vs. 8.6%; P = 0.002). Indeed, there was a stepwise increase in 30-day mortality over the quintiles of deprivation from 7.3% (Quintile 1) to 8.8, 10.0, 10.0 and 9.3%, respectively. Univariate logistic regression of the deprivation indices (quintiles) against outcome showed an increased risk (P = 0.002) of a 30-day death with odds ratios (ORs), respectively (compared with lowest deprivation quintile) of 1.39 [95% confidence intervals (CI) 1.21, 1.58], 1.47 (95% CI 1.29, 1.68), 1.44 (95% CI 1.26, 1.64) and 1.39 (95% CI 1.22, 1.59). The deprivation index was an independent predictor of outcome in a model when adjusted for illness severity and co-morbidity. The fully adjusted OR for a 30-day death was increased by 31% (P = 0.001) for patients in the upper half of the deprivation index distribution (OR 1.35; 95% CI 1.23, 1.48; P < 0.001).

CONCLUSION

Deprivation, independent of co-morbidity or acute illness severity, is an independent predictor of 30-day mortality in acute medical admissions.

Cocaine-related admissions to an intensive care unit: a five-year study of incidence and outcomes

Cocaine misuse is increasing and it is evidently considered a relatively safe drug of abuse in Ireland. To address this perception, we reviewed the database of an 18-bed Dublin intensive care unit, covering all admissions from 2003 to 2007. We identified cocaine-related cases, measuring hospital mortality and long-term survival in early 2009. Cocaine-related admissions increased from around one annually in 2003-05 to 10 in 2007. Their median (IQR [range]) age was 25 (21-35 [17-47]) years and 78% were male. The median (IQR [range]) APACHE II score was 16 (11-27 [5-36]) and length of intensive care stay was 5 (3-9 [1-16]) days. Ten patients died during their hospital stay. A further five had died by the time of follow-up, a median of 24 months later. One was untraceable. Cocaine toxicity necessitating intensive care is increasingly common in Dublin. Hospital mortality in this series was 52%. These findings may help to inform public attitudes to cocaine.

Warning: bisphosphonates and osteochemonecrosis of the jaws

The aim of this article is to highlight the link between bisphosphonates and osteonecrotic lesions of the jaws ("osteochemonecrosis") and to alert general practitioners to the implications these drugs may have on their day-to-day practice. We review the use of this class of drug, the indications for which have widened recently, describe their effect on bone metabolism and outline the proposed mechanism for bisphosphonate-induced osteochemonecrosis. Predisposing and initiating factors and management are outlined, and suggestions made as to how the dental profession can help with this increasingly prevalent problem.

The effect of rectal diclofenac on pruritus in patients receiving intrathecal morphine

In this prospective randomised study, pruritus and pain were evaluated in patients undergoing abdominal surgery in which intrathecal morphine was administered. Each patient received intrathecal morphine 0.3 mg prior to induction, followed by a standard anaesthetic. The patients were randomly allocated to one of two groups. One group received 100 mg of rectal diclofenac immediately post-induction. Patients receiving diclofenac had significantly lower pruritus scores at 30 min (p = 0.0076), 2, 4, 8 and 24 h postoperatively, as well as significantly reduced pain scores at each time point (p < 0.0001 at each study interval). Morphine consumption in the first 24 h was also significantly lower in this group. In conclusion, rectal administration of diclofenac significantly reduces the incidence and severity of postoperative pruritus. It also significantly reduces pain and further analgesic requirements postoperatively.

Lineage-specific and differentiation-dependent expression of K12 keratin in rabbit corneal/limbal epithelial cells: cDNA cloning and northern blot analysis

Corneal epithelial cells synthesize an acidic (55 kDa) K12 and a basic (64 kDa) K3 keratin as their major differentiation products during an advanced stage of differentiation. In this paper, we describe the cDNA cloning of rabbit K12 keratin. We used a 36 base pairs (bp) oligonucleotide corresponding to a consensus sequence of many known acidic keratins as a probe to screen a cDNA library of normal rabbit corneal epithelium. Several partial cDNA clones were isolated. Hybrid-selection showed that the 3'keratin chain-specific portion of the cDNA hybridizes with K12 mRNA. A rabbit antiserum raised against the C-terminus of the cDNA-deduced amino acid sequence recognizes, in immunoblotting, the K12 keratin. In situ hybridization showed that K12 mRNA is present in all cell layers of central corneal epithelium, but in only the suprabasal cells of limbal epithelium indicating a parallel expression pattern between K12 and K3. Cultured rabbit corneal epithelial cells initially synthesize K14/K5 keratins, but later when the cells become heavily stratified they synthesize large quantities of K12 and K3 mRNAs, as detected by Northern blotting. Cultured esophageal epithelial cells do not make K12 mRNA confirming the tissue-specificity of K12 expression. Although it has been suggested that conjunctival epithelial cells can trans-differentiate into a bona fide corneal epithelium, we showed here that cultured conjunctival cells do not synthesize significant amounts of K12/K3 mRNAs. These results strongly suggest that conjunctival epithelial cells, whose differentiation can be modulated significantly by the extracellular matrix, form a lineage intrinsically distinct from the corneal/limbal epithelial lineage.

A 300 bp 5′-upstream sequence of a differentiation-dependent rabbit K3 keratin gene can serve as a keratinocyte-specific promoter

Keratinocytes of the suprabasal compartment of many stratified epithelia synthesize as a major differentiation product a keratin pair, consisting of an acidic and a basic keratin, which accounts for 10–20% of the newly synthesized proteins. While genes of several differentiation-related keratins have been cloned and studied, relatively little is known about the molecular basis underlying their tissue-specific and differentiation-dependent expression. We have chosen to study, as a prototype of these genes, the gene of K3 keratin, which has the unique property of being expressed in the majority of corneal epithelial basal cells but suprabasally in peripheral cornea, the site of corneal epithelial stem cells. Using a monoclonal antibody, AE5, specific for K3 keratin, and a fragment of human K3 gene as probes, we have isolated several cDNA and genomic clones of rabbit K3 keratin. One genomic clone has been sequenced and characterized, and the identity of its coding sequence with that of cDNAs indicates that it corresponds to the single, functional rabbit K3 gene. Transfection assays showed that its 3.6 kb 5′-upstream sequence can drive a chloramphenicol acetyl transferase (CAT) reporter gene to express in cultured corneal and esophageal epithelial cells, but not in mesothelial and kidney epithelial cells or fibroblasts, all of rabbit origin. Serial deletion experiments narrowed this keratinocyte-specific promoter to within -300 bp upstream of the transcription initiation site. Its activity is not regulated by the coding or 3′-noncoding sequences that have been tested so far. This 300 bp 5′-upstream sequence of K3 keratin gene, which can function in vitro as a keratinocyte-specific promoter, contains two clusters of partially overlapping motifs, one with an NFkB consensus sequence and another with a GC box. The combinatorial effects of these multiple motifs and their cognate binding proteins may play an important role in regulating the expression of this tissue-restricted and differentiation-dependent keratin gene.

Historical reflections on hypertension

Sixty million Americans have hypertension, a major cardiovascular risk factor. Its presence accelerates the atherosclerotic process, producing strokes, heart attacks, heart failure, renal failure, and peripheral vascular disease. This article highlights the historical landmarks in the study of this disease from the first documented measurement of blood pressure in 1733, through the most recent pharmacologic approaches to treatment. In addition, the roles of the kidney and the renin-angiotensin-aldosterone system are examined.

Differentiation-related expression of a major 64K corneal keratin in vivo and in culture suggests limbal location of corneal epithelial stem cells

In this paper we present keratin expression data that lend strong support to a model of corneal epithelial maturation in which the stem cells are located in the limbus, the transitional zone between cornea and conjunctiva. Using a new monoclonal antibody, AE5, which is highly specific for a 64,000-mol-wt corneal keratin, designated RK3, we demonstrate that this keratin is localized in all cell layers of rabbit corneal epithelium, but only in the suprabasal layers of the limbal epithelium. Analysis of cultured corneal keratinocytes showed that they express sequentially three major keratin pairs. Early cultures consisting of a monolayer of "basal" cells express mainly the 50/58K keratins, exponentially growing cells synthesize additional 48/56K keratins, and postconfluent, heavily stratified cultures begin to express the 55/64K corneal keratins. Cell separation experiments showed that basal cells isolated from postconfluent cultures contain predominantly the 50/58K pair, whereas suprabasal cells contain additional 55/64K and 48/56K pairs. Basal cells of the older, postconfluent cultures, however, can become AE5 positive, indicating that suprabasal location is not a prerequisite for the expression of the 64K keratin. Taken together, these results suggest that the acidic 55K and basic 64K keratins represent markers for an advanced stage of corneal epithelial differentiation. The fact that epithelial basal cells of central cornea but not those of the limbus possess the 64K keratin therefore indicates that corneal basal cells are in a more differentiated state than limbal basal cells. These findings, coupled with the known centripetal migration of corneal epithelial cells, strongly suggest that corneal epithelial stem cells are located in the limbus, and that corneal basal cells correspond to "transient amplifying cells" in the scheme of "stem cells----transient amplifying cells----terminally differentiated cells."