Bis[2-(Methacryloyloxy) Ethyl] Phosphate as a Primer for Enamel and Dentine

Dental resin composites are commonly used in the restorative management of teeth via adhesive bonding, which has evolved significantly over the past few decades. Although current self-etch bonding systems decrease the number of clinical steps, the acidic functional monomers employed exhibit a limited extent of demineralization of enamel in comparison to phosphoric acid etchants, and the resultant superficial ionic interactions are prone to hydrolysis. This study evaluates the etching of primers constituted with bis[2-(methacryloyloxy) ethyl] phosphate (BMEP) of dental hard tissue, interfacial characteristics, and inhibition of endogenous enzymes. We examine the incorporation of 2 concentrations of BMEP in the formulation of experimental primers used with a hydrophobic adhesive to constitute a 2-step self-etching bonding system and compare to a commercial 10–methacryloyloxydecyl dihydrogen phosphate (10-MDP)–containing system. The interaction of the primer with enamel and dentine was characterized using scanning electron, confocal laser scanning, and Raman microscopy while the polymerization reaction between the BMEP primers and hydroxyapatite was evaluated by Fourier-transform infrared spectroscopy. The inhibitory effect against matrix metalloproteinase (MMP) enzymes of these primers was studied and percentage of inhibition analyzed using 1-way analysis of variance and Tukey’s post hoc test (P < 0.05). Results of the scanning electron microscopy micrographs demonstrated potent etching of both enamel and dentine with the formation of longer resin tags with BMEP primers compared to the 10-MDP–based system. The BMEP polymerized on interaction with pure hydroxyapatite in the dark, while the 10-MDP primer exhibited the formation of salts. Furthermore, BMEP primers were able to inhibit MMP activity in a dose-dependent manner. BMEP could be used as a self-etching primer on enamel and dentine, and the high degree of polymerization in the presence of hydroxyapatite can contribute to an increased quality of the resin polymer network, prompting resistance to gelatinolytic and collagenolytic degradation.

Consensus recommendations for optimizing biomarker testing to identify and treat advanced EGFR-mutated non-small-cell lung cancer

The advent of personalized therapy for non-small-cell lung carcinoma (nsclc) has improved patient outcomes. Selection of appropriate targeted therapy for patients with nsclc now involves testing for multiple biomarkers, including EGFR. EGFR mutation status is required to optimally treat patients with nsclc, and thus timely and accurate biomarker testing is necessary. However, in Canada, there are currently no standardized processes or methods in place to ensure consistent testing implementation. That lack creates challenges in ensuring that all appropriate biomarkers are tested for each patient and that the medical oncologist receives the results for making informed treatment decisions in a timely way. An expert multidisciplinary working group was convened to create consensus recommendations about biomarker testing in advanced nsclc in Canada, with a primary focus on EGFR testing. Recognizing that there are biomarkers beyond EGFR that require timely identification, the expert multidisciplinary working group considered EGFR testing in the broader context of integration into complex lung biomarker testing. Primarily, the panel of experts recommends that all patients with nonsquamous nsclc, regardless of stage, should undergo comprehensive reflex biomarker testing at diagnosis with targeted next-generation sequencing. The panel also considered the EGFR testing algorithm and the challenges associated with the pre-analytic, analytic, and post-analytic elements of testing. Strategies for funding testing by reducing silos of single biomarker testing for EGFR and for optimally implementing the recommendations presented here and educating oncology professionals about them are also discussed.

Canadian consensus: a new systemic treatment algorithm for advanced EGFR-mutated non-small-cell lung cancer

Background

Multiple clinical trials for the treatment of advanced EGFR-mutated non-small-cell lung cancer (nsclc) have recently been reported. As a result, the treatment algorithm has changed, and many important clinical questions have been raised:■ What is the optimal first-line treatment for patients with EGFR-mutated nsclc?■ What is preferred first-line treatment for patients with brain metastasis?■ What is the preferred second-line treatment for patients who received first-line first- or second-generation tyrosine kinase inhibitors (tkis)?■ What is the preferred treatment after osimertinib?■ What evidence do we have for treating patients whose tumours harbour uncommon EGFR mutations?

Methods

A Canadian expert panel was convened to define the key clinical questions, review recent evidence, and discuss and agree on practice recommendations for the treatment of advanced EGFR-mutated nsclc.

Results

The published overall survival results for osimertinib, combined with its central nervous system activity, have led to osimertinib becoming the preferred first-line treatment for patients with common EGFR mutations, including those with brain metastasis. Other agents could still have a role, especially when osimertinib is not available or not tolerated. Treatment in subsequent lines of therapy depends on the first-line therapy or on T790M mutation status. Treatment recommendations for patients whose tumours harbour uncommon EGFR mutations are guided mainly by retrospective and limited prospective evidence. Finally, the evidence for sequencing and combining tkis with chemotherapy, angiogenesis inhibitors, checkpoint inhibitors, and other new therapeutics is reviewed.

Conclusions

This Canadian expert consensus statement and algorithm were driven by significant advances in the treatment of EGFR-mutated nsclc.

Biomarkers of immune checkpoint inhibitor efficacy in cancer

Immune checkpoint inhibitor-based therapies that target ctla-4, PD-1, or the PD-1 ligand PD-L1 have received approval in Canada and many parts of the world for the treatment of melanoma, renal cell cancer, urothelial cancer, classical Hodgkin lymphoma, and non-small-cell lung cancer. However only a small proportion of patients derive long-term clinical benefit. Here, we describe the biomarkers associated with the complex relationship between tumour-related immune stimulus, T cell-mediated immune response, and immune modulation of the microenvironment that can help to predict improved patient outcomes.

Crizotinib inhibition of ROS1-positive tumours in advanced non-small-cell lung cancer: a Canadian perspective

The ros1 kinase is an oncogenic driver in non-small-cell lung cancer (nsclc). Fusion events involving the ROS1 gene are found in 1%-2% of nsclc patients and lead to deregulation of a tyrosine kinase-mediated multi-use intracellular signalling pathway, which then promotes the growth, proliferation, and progression of tumour cells. ROS1 fusion is a distinct molecular subtype of nsclc, found independently of other recognized driver mutations, and it is predominantly identified in younger patients (<50 years of age), women, never-smokers, and patients with adenocarcinoma histology. Targeted inhibition of the aberrant ros1 kinase with crizotinib is associated with increased progression-free survival (pfs) and improved quality-of-life measures. As the sole approved treatment for ROS1-rearranged nsclc, crizotinib has been demonstrated, through a variety of clinical trials and retrospective analyses, to be a safe, effective, well-tolerated, and appropriate treatment for patients having the ROS1 rearrangement. Canadian physicians endorse current guidelines which recommend that all patients with nonsquamous advanced nsclc, regardless of clinical characteristics, be tested for ROS1 rearrangement. Future integration of multigene testing panels into the standard of care could allow for efficient and cost-effective comprehensive testing of all patients with advanced nsclc. If a ROS1 rearrangement is found, treatment with crizotinib, preferably in the first-line setting, constitutes the standard of care, with other treatment options being investigated, as appropriate, should resistance to crizotinib develop.

A Canadian guideline on the use of next-generation sequencing in oncology

Rapid advancements in next-generation sequencing (ngs) technology have created an unprecedented opportunity to decipher the molecular profile of tumours to more effectively prevent, diagnose, and treat cancer. Oncologists now have the option to order molecular tests that can guide treatment decisions. However, to date, most oncologists have received limited training in genomics, and they are now faced with the challenge of understanding how such tests and their interpretation align with patient management. Guidance on how to effectively use ngs technology is therefore needed to aid oncologists in applying the results of genomic tests. The Canadian guideline presented here describes best practices and unmet needs related to ngs-based testing for somatic variants in oncology, including clinical application, assay and sample selection, bioinformatics and interpretation of reports performed by laboratories, patient communication, and clinical trials.

Canadian consensus: oligoprogressive, pseudoprogressive, and oligometastatic non-small-cell lung cancer

Background

Little evidence has been generated for how best to manage patients with non-small-cell lung cancer (nsclc) presenting with rarer clinical scenarios, including oligometastases, oligoprogression, and pseudoprogression. In each of those scenarios, oncologists have to consider how best to balance efficacy with quality of life, while maximizing the duration of each line of therapy and ensuring that patients are still eligible for later options, including clinical trial enrolment.

Methods

An expert panel was convened to define the clinical questions. Using case-based presentations, consensus practice recommendations for each clinical scenario were generated through focused, evidence-based discussions.

Results

Treatment strategies and best-practice or consensus recommendations are presented, with areas of consensus and areas of uncertainty identified.

Conclusions

In each situation, treatment has to be tailored to suit the individual patient, but with the intent of extending and maximizing the use of each line of treatment, while keeping treatment options in reserve for later lines of therapy. Patient participation in clinical trials examining these issues should be encouraged.

Targeting the PD-1/PD-L1 axis for the treatment of non-small-cell lung cancer

Lung cancer is the leading cause of cancer-specific death among Canadians, with non-small-cell lung cancer (nsclc) being the most common histologic variant. Despite advances in the understanding of the molecular biology of nsclc, the survival rate for this malignancy is still poor. It is now understood that, to evade detection and immune clearance, nsclc tumours overexpress the immunosuppressive checkpoint protein programmed death ligand 1 (PD-L1). Inhibiting the PD-1/PD-L1 axis with monoclonal antibodies has significantly changed the treatment landscape in nsclc during the last 5 years. Despite evidence of clinical response in some patients, only approximately 20% of patients obtain any durable benefit, and many of the patients who do respond ultimately relapse with drug-resistant disease. The identification of patients who are most likely to benefit from such therapy is therefore important. In the present review, we cover the basics of the PD-1/PD-L1 axis and its clinical significance in nsclc, biomarkers that are predictive of treatment response, relevant clinical trials of PD-1/PD-L1 blockade completed to date, and proposed mechanisms of acquired therapeutic resistance.

An evaluation of the influence of teeth and the labial soft tissues on the perceived aesthetics of a smile

Objective The aim of this study was to investigate how the lips and teeth may affect the perceived aesthetics of a given smile. Lips and teeth were collectively assessed in different fields of view to see how they may contribute to smile aesthetics. The perception of 'beauty' was assessed to determine whether differences existed between; dentists, non-dentists, males and females.Methods Five subjects were photographed to produce the following views: 1) retracted anterior teeth; 2) lips at rest; 3) zoomed smile; and 4) smile showing the lower face. Images were compiled in a survey questionnaire and shown to respondents who ranked the subjects in order of aesthetic appeal. Kendall's coefficient of concordance (W) and median rank scores were used to determine the statistical significance.Results All groups demonstrated statistically significant agreement in the perception of beauty. Both the teeth and lips seemed to contribute similarly to the attractiveness of a smile. Dentists seemed to be more influenced by teeth in a zoomed smile view, however, this was negated when viewing a broader field of view. All other groups showed no difference in perception of aesthetics with changing field of view.Conclusion Both lips and teeth seem to contribute to the aesthetic appeal of a smile. Dentists may have a tendency to place a disproportionate weight to teeth when assessing a smile close up.

Canadian consensus: inhibition of ALK-positive tumours in advanced non-small-cell lung cancer

Anaplastic lymphoma kinase (alk) is an oncogenic driver in non-small-cell lung cancer (nsclc). Chromosomal rearrangements involving the ALK gene occur in up to 4% of nonsquamous nsclc patients and lead to constitutive activation of the alk signalling pathway. ALK-positive nsclc is found in relatively young patients, with a median age of 50 years. Patients frequently have brain metastasis. Targeted inhibition of the alk pathway prolongs progression-free survival in patients with ALK-positive advanced nsclc. The results of several recent clinical trials confirm the efficacy and safety benefit of crizotinib and ceritinib in this population. Canadian oncologists support the following consensus statement: All patients with advanced nonsquamous nsclc (excluding pure neuroendocrine carcinoma) should be tested for the presence of an ALK rearrangement. If an ALK rearrangement is present, treatment with a targeted alk inhibitor in the first-line setting is recommended. As patients become resistant to first-generation alk inhibitors, other treatments, including second-generation alk inhibitors can be considered.

Current concepts on the management of tooth wear: part 2. Active restorative care 1: the management of localised tooth wear

This second of the four part series of articles on the current concepts of tooth wear management will focus on the provision of active restorative care, where the implementation of a preventative, passive approach may prove insufficient to meet the patient's expectations, or indeed prove to be sufficiently adequate to address the extent of the underlying pathology to the desired level of clinical satisfaction. The active restorative management of cases presenting with localised tooth wear (of either the anterior, posterior, maxillary or mandibular variety) will be considered in depth in this paper, including a description of the commonly applied techniques and treatment strategies, where possible illustrated by case examples.

PKC-Dependent Phosphorylation May Regulate the Ability of Connexin43 to Inhibit DNA Synthesis

Phosphorylation affects several biological functions of connexin43 (Cx43), although its role on Cx43-mediated inhibition of DNA synthesis is not known. Previous studies showed increased Cx43 phosphorylation on serine in response to growth factor stimulation of cardiomyocytes, mediated by protein kinase C-epsilon (PKCepsilon). Here we report that activation of PKCepsilon is also necessary for stimulation of cardiomyocyte DNA synthesis and mitosis. We have investigated the participation of specific serine residues that are putative PKC targets in producing phosphorylated Cx43 species and also in regulating DNA synthesis in cardiomyocytes. Interference with the PKC signaling system and/or the phosphorylation of specific amino-acids of Cx43 may allow regulation of the mitogenic response.

Factors impacting survival of patients with post-surgical disease recurrence in non-small cell lung cancer (NSCLC)

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Background: There are no standard recommendations for follow-up of NSCLC patients post surgery. To be of value, follow-up should detect disease recurrence early enough to allow timely initiation of effective treatment leading to clinical benefit. Methods: Patients diagnosed with NSCLC in Manitoba, Canada, who underwent a surgical procedure at the two teaching hospitals between January 1996 and December 2001, were identified using the Cancer Registry. We included 435 patients who underwent complete surgical resection of pathologic Stage IA to IIB disease. To date, a detailed retrospective chart review has been completed on 249 of these patients. Median follow-up of this population was 3.45 years. Results: The median age was 66.4 years and 51% were male. 68% had Stage I disease. Lobectomy (73%) was more commonly performed over wedge resection (14%) and pneumonectomy (13%). The most frequent histological diagnosis was adenocarcinoma (52%) followed by squamous cell (29%) and bronchoalveolar carcinoma (13%). Disease recurred in 68% of patients. Recurrence was detected in 52 patients by routine imaging during follow-up. 117 had symptoms suggestive of disease recurrence prompting additional investigation. Median time to recurrence was 1.2 and 1.5 years (NS) respectively for the symptomatic and asymptomatic group. The median overall survival of the asymptomatic patients (4.19 years) was significantly (p = 0.007) greater than the symptomatic patients (2.66 years). Similarly, the median survival from the time of recurrence was greater for the asymptomatic patients (1.6 vs. 0.7 years, p = 0.004). A multivariate analysis identified symptoms (p = 0.02) at the time of recurrence and stage (p = 0.01) of the disease at the initial presentation as significant independent factors impacting overall survival. Only the absence of symptoms had a significant association (p = 0.006) with improved survival after diagnosis of recurrent disease. Conclusions: The diagnosis of recurrence while patients are asymptomatic resulted in better survival. This may suggest that routine post-surgical follow-up of patients with early NSCLC is justified.

No significant financial relationships to disclose.

Clinical performance of Rochette bridges used as immediate provisional restorations for single unit implants in general practice

A retrospective clinical audit of the role and survival of 69 Rochette bridges used as immediate provisional restorations for single tooth, implant-retained crowns was carried out over the period between February 1991 and May 2001. In each case the extracted tooth was immediately temporised using a Rochette bridge with a single wing and pontic and cemented to the abutment tooth without any tooth preparation (Phase I). This bridge was removed at the time of implant placement and recemented (Phase II). At the implant exposure stage the bridge was removed and discarded. In Phase I, 15.9% of the bridges required recementation and 27.5% of the bridges required recementations in phase 2; 7.2% of the bridges required recementations in both phases. An 80% probability of survival was noted after an interval of 200 days for phase I and a 78% probability of survival over the same time interval was observed for Phase II. A significant debond rate was observed when the retainer was a canine in comparison to the other bridges in Phase I. In Phase I the spring cantilever debond rate was significantly higher than that observed on the other bridges. More debondings were observed in males (25.8%) compared with females (7.9%) in Phase I. More debondings were noted in the maxilla than in the mandible in Phase II. The performance characteristics of the metal acrylic Rochette bridge observed in this report supports the conclusion that this type of restoration is an effective means of immediate temporisation for patients undergoing single tooth implant retained restorations.

Expression of a lymphatic endothelial cell marker in benign and malignant vascular tumors

Tumors of endothelial cell origin are relatively common. Soft tissue tumors and numerous subtypes of benign and malignant vascular tumors have been described; the histogenesis of many of these tumors is uncertain, and distinguishing between benign and malignant vascular tumors, some of which express lymphatic endothelial cell markers, can be problematic. In the present study, immunophenotypic expression of a novel hyaluronan receptor (LYVE-1), which is expressed by endothelial cells of normal lymphatic vessels but not blood vessels, was determined in benign and malignant vascular tumors. It was found that, except in lymphangiomas, intramuscular hemangiomas, and Masson's hemangiomas, endothelial cells in benign blood vessel tumors (including capillary and cavernous hemangiomas, glomus tumors, pyogenic granulomas, and epithelioid hemangiomas) were negative for LYVE-1, and that all angiosarcomas and Kaposi's sarcomas were positive for LYVE-1. Expression of LYVE-1 and other lymphatic endothelial cell markers in relatively few vascular neoplasms has implications for the histogenesis of these lesions, and may prove useful in distinguishing angiosarcoma and Kaposi's sarcoma from most common benign vascular tumors.

Distribution of lymphatic vessels in normal and arthritic human synovial tissues

OBJECTIVES

To investigate the distribution of lymphatic vessels in normal, rheumatoid arthritis (RA) and osteoarthritis (OA) synovium.

METHODS

Synovial tissues from 5 normal controls, 14 patients with RA, and 16 patients with OA were studied. Lymphatic vessels were identified by immunohistochemistry using antibodies directed against the lymphatic endothelial hyaluronan receptor (LYVE-1) and recognised blood vessel endothelial markers (factor VIII, CD34, CD31).

RESULTS

Lymphatic vessels were found in all zones of the normal, OA, and RA synovial membrane. Few lymphatic vessels were seen in the sublining zone in normal and OA synovium which did not show villous hypertrophy. However, in both RA synovium and OA synovium showing villous hypertrophy and a chronic inflammatory cell infiltrate, numerous lymphatic vessels were seen in all zones of the synovial membrane, including the sublining zone of the superficial subintima.

CONCLUSIONS

Lymphatic vessels are present in normal and arthritic synovial tissues and are more numerous and prominent where there is oedema and an increase in inflammatory cells in the subintima, particularly in RA. This may reflect increased transport of hyaluronan and leucocyte trafficking in inflamed synovial tissues.

Biodegradation of RDX within soil-water slurries using a combination of differing redox incubation conditions

Biodegradation of 14C-tagged hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) was studied in aerobic, anaerobic, and anaerobic/aerobic slurries to identify the conditions maximizing RDX-mineralization in Cornhusker Army Ammunition Plant (CAAP, NE) groundwater. Supplementation with phosphate and adequate quantities of acetate caused 25% mineralization of RDX in 3 weeks by microorganisms native to CAAP. Under anaerobic conditions, the same supplementation resulted in 20% mineralization in 3 weeks and 30% mineralization in 6 weeks. The highest degree of mineralization (50%) was obtained under aerobic conditions when the contaminated groundwater was augmented with a consortium of three microbes isolated from another RDX contaminated soil (Hastings, NE) in addition to supplemented with phosphate and acetic acid. Use of complex organic sources (potato or corn starch) slowed down the rates of mineralization under anaerobic conditions, but rapid mineralization ensued as soon as the aerobic conditions were created. Final RDX concentrations in aqueous phase were below detection limit under most conditions. Assimilation of RDX by the cells was negligible.

Abuse of Coricidin HBP cough & cold tablets: episodes recorded by a poison center

Cases involving ingestion of a dextromethorphan-containing product recorded at a poison control center were studied. A retrospective review of all consultations involving the ingestion of Coricidin HBP Cough & Cold tablets recorded by the California Poison Control System was conducted for the period from January 1 to October 1, 2000. Computerized charts on the consultations were reviewed to obtain data on patient age and sex, number of tablets taken, reason for tablet ingestion, symptoms, treatment, disposition, and outcome. A total of 92 charts (for 92 patients) documenting Coricidin HBP Cough & Cold tablet ingestion were reviewed. The reason for tablet ingestion was classified as abuse in 65 patients (71%), a suicide attempt in 8 (9%), misuse in 1 (1%), malicious administration in 1 (1%), and normal use (but with an adverse drug reaction) in 1 (1%); 16 patients (17%) consumed the tablets for an unknown reason. The 92 patients comprised 42 males and 50 females. Among all patients, 78 (85%) were 13-17 years old, and among those classified as having abusive intent, 58 (89%) were in the same age range. The most commonly reported signs and symptoms associated with ingestion were tachycardia (50 patients), hypertension (29), lethargy (40), mydriasis (20), agitation (15), ataxia or dizziness (20), and vomiting (9). Sixty-one patients (66%) had some alteration in mental status. Fifty-six (61%) were treated in the emergency department; 11 (12%) were admitted. All patients recovered completely. Information on the ingestion of Coricidin HBP Cough & Cold tablets recorded at a poison control center indicated a high rate of abuse of the product among teenagers.

LYVE-1, the lymphatic system and tumor lymphangiogenesis

Previous research into hyaluronan (HA) has focused on the role of this abundant tissue glycosaminoglycan in promoting cell migration through interactions with its transmembrane receptor CD44 on inflammatory leukocytes and tumor cells. The recent discovery of a new HA receptor, LYVE-1 (lymphatic vessel endothelial HA receptor), expressed predominantly in lymphatic vessels, highlights another aspect of HA biology: its continuous transit through the lymphatic system and its potential involvement in lymph node homing by CD44+ leukocytes and tumor cells. The functional role of LYVE-1 in lymphatic vessels and its application as a marker to study tumor lymphangiogenesis are important areas of investigation.

Mouse LYVE-1 is an endocytic receptor for hyaluronan in lymphatic endothelium

The glycosaminoglycan hyaluronan is a key substrate for cell migration in tissues during inflammation, wound healing, and neoplasia. Unlike other matrix components, hyaluronan (HA) is turned over rapidly, yet most degradation occurs not locally but within distant lymph nodes, through mechanisms that are not yet understood. While it is not clear which receptors are involved in binding and uptake of hyaluronan within the lymphatics, one likely candidate is the lymphatic endothelial hyaluronan receptor LYVE-1 recently described in our laboratory (Banerji, S., Ni, J., Wang, S., Clasper, S., Su, J., Tammi, R., Jones, M., and Jackson, D.G. (1999) J. Cell Biol. 144, 789-801). Here we present evidence that LYVE-1 is involved in the uptake of hyaluronan by lymphatic endothelial cells using a new murine LYVE-1 orthologue identified from the EST data base. We show that mouse LYVE-1 both binds and internalizes hyaluronan in transfected 293T fibroblasts in vitro and demonstrate using immunoelectron microscopy that it is distributed equally among the luminal and abluminal surfaces of lymphatic vessels in vivo. In addition, we show by means of specific antisera that expression of mouse LYVE-1 remains restricted to the lymphatics in homozygous knockout mice lacking a functional gene for CD44, the closest homologue of LYVE-1 and the only other Link superfamily HA receptor known to date. Together these results suggest a role for LYVE-1 in the transport of HA from tissue to lymph and imply that further novel hyaluronan receptors must exist that can compensate for the loss of CD44 function.

LYVE-1, a new homologue of the CD44 glycoprotein, is a lymph-specific receptor for hyaluronan

The extracellular matrix glycosaminoglycan hyaluronan (HA) is an abundant component of skin and mesenchymal tissues where it facilitates cell migration during wound healing, inflammation, and embryonic morphogenesis. Both during normal tissue homeostasis and particularly after tissue injury, HA is mobilized from these sites through lymphatic vessels to the lymph nodes where it is degraded before entering the circulation for rapid uptake by the liver. Currently, however, the identities of HA binding molecules which control this pathway are unknown. Here we describe the first such molecule, LYVE-1, which we have identified as a major receptor for HA on the lymph vessel wall. The deduced amino acid sequence of LYVE-1 predicts a 322-residue type I integral membrane polypeptide 41% similar to the CD44 HA receptor with a 212-residue extracellular domain containing a single Link module the prototypic HA binding domain of the Link protein superfamily. Like CD44, the LYVE-1 molecule binds both soluble and immobilized HA. However, unlike CD44, the LYVE-1 molecule colocalizes with HA on the luminal face of the lymph vessel wall and is completely absent from blood vessels. Hence, LYVE-1 is the first lymph-specific HA receptor to be characterized and is a uniquely powerful marker for lymph vessels themselves.

Characterization of a functional hyaluronan-binding domain from the human CD44 molecule expressed in Escherichia coli

The CD44 molecule is a widely distributed cell surface receptor for the extracellular matrix glycosaminoglycan hyaluronan. The ligand-binding site which is located in the membrane distal portion of the molecule encompasses a region of approximately 100 amino acids termed the Link domain, a structural unit that is conserved among members of the Hyaladherin superfamily which includes cartilage link protein, aggrecan, and tumor necrosis factor-stimulated gene-6 (TSG-6). In contrast to these other Hyaladherins, however, the ligand-binding domain of CD44 appears to extend beyond the Link domain to involve additional basic residues located toward the membrane proximal region. Furthermore, recent molecular modeling studies indicate that within the CD44 Link domain itself, the spatial arrangement of critical residues involved in HA binding is likely to differ significantly from the prototypic TSG-6 Link module. In order to obtain material to solve the CD44 solution structure we have developed an optimized method for the expression and purification of functionally active CD44 ectodomains encompassing both the Link module and the additional downstream HA-binding residues in Escherichia coli. Here we describe the details of the method which involves solubilization of recombinant CD44 from inclusion bodies in 8 M urea, followed by refolding and purification of intact monomers using size-exclusion and reverse-phase chromatography. We show the method yields CD44 molecules that (1) retain reactivity with a panel of conformation-sensitive antibodies, (2) possess similar hyaluronan-binding characteristics to authentically folded CD44 molecules expressed in eukaryotic cells, and (3) display one-dimensional NMR spectra that indicate the presence of a single conformational species. This method should enable sufficient amounts of functional CD44 Link module to be produced for comprehensive structural analyses by multidimensional NMR spectroscopy.

Principles of drug administration in renal insufficiency

Normal renal function is important for the excretion and metabolism of many drugs. Renal diseases which affect glomerular blood flow and filtration, tubular secretion, reabsorption and renal parenchymal mass alter drug clearances and lead to the need for alterations in dosage regimens to optimise therapeutic outcome and minimise the risk of toxicity. Renal disease is increasing and the cost of care has risen progressively over the past decade. Part of these costs is related to inappropriate drug therapy and excessive drug use. Although there are a variety of methods for evaluating the various aspects of renal function, the most practical and commonly used clinical measure of renal function is estimated creatinine clearance (CLCR) as a marker for glomerular filtration. This is useful since alterations in drug clearance are proportional to alterations in CLCR, and this relationship is used as the basis for changing doses and dosage intervals for drugs which are largely renally excreted. Two populations, neonates and the elderly, are at risk of inappropriate drug dosage due to physiological changes in renal function. Estimated CLCR may not be the best method of evaluating renal function in these patients, and dosage regimens should be carefully considered. Renal insufficiency and concurrent drug therapy used in these populations can either increase or decrease drug absorption, depending on the particular agent. Drug distribution may be altered in renal insufficiency due to pH-dependent protein binding and reduced protein (primarily albumin) levels. Interestingly, renal disease may affect hepatic as well as renal drug metabolism; the exact mechanisms for these changes are not well understood. The most important quantitative pharmacokinetic change is excretion. Glomerular filtration and tubular process may both be affected but not to the same extent, and the type of renal disease may differentially affect filtration and excretion. Drug removal by dialysis is dependent on a number of factors, including the characteristics of a particular drug and the type of dialysis and equipment used. Therapeutic outcomes may be evaluated using end-points such as plasma concentrations, patient outcomes such as reduction in fever or negative cultures, and system-wide changes such as drug-use or laboratory-use patterns.

Genetic diversity at the internal transcribed spacer regions of the rRNA operon among isolates of Pneumocystis carinii from AIDS patients with recurrent pneumonia

The opportunistic fungal pathogen Pneumocystis carinii sp. f. hominis is a frequent cause of pneumonia in the immunocompromised host. Analysis of genetic variation among isolates of P. carinii sp. f. hominis from 12 human immunodeficiency virus (HIV)-infected persons with single and multiple episodes of P. carinii pneumonia was undertaken at the internal transcribed spacer (ITS) regions of the nuclear rRNA operon. In samples from 24 episodes of pneumonia, 10 different types of P. carinii sp. f. hominis were identified. More than 1 sequence type was observed in 8 samples, indicating that mixed infection with different types of P. carinii sp. f. hominis is not uncommon. In 4 of 7 patients with recurrent episodes of pneumonia, the sequence types observed at the second episode were different from those of the first, suggesting the occurrence of both reactivation of a previously acquired infection and reinfection from an exogenous source.

Tuberculosis in San Diego county: a border community perspective

OBJECTIVES

To describe the epidemiology of active disease caused by Mycobacterium tuberculosis in San Diego County from 1989 to 1993 and to identify the specific subgroups for whom the impact of the disease was most pronounced.

METHOD

The authors reviewed all 1860 reports of verified tuberculosis (TB) cases included in the surveillance database maintained by the San Diego County Health Department's TB Control Program. Data were analyzed by age, gender, ethnicity, nativity, HIV co-infection, major site of infection, and drug resistance.

RESULTS

Between 1989 and 1993. San Diego County witnessed a greater increase (77.7%) in the number of incident TB cases than the state of California as a whole (22.8%) or the United States (9.9%). The local resurgence of TB was reflected in increasing case counts among specific subpopulations--immigrants from countries with high endemic rates of TB (62.5% of the new cases), U.S.-born members of minority groups, the elderly, and young adult males.

CONCLUSIONS

Tuberculosis cases in San Diego County have increased each year since 1989, with certain population subgroups exhibiting more dramatic increases in case rates than those reported nationally. San Diego County is one of the principal entry points for the western United States and a popular travel destination. These factors have led to a dramatic increase in the incidence of TB in the county. A range of tailored surveillance, treatment, and control strategies--some of which have already been implemented--will be needed to control the spread of the disease.

Analysis of genetic diversity at the arom locus in isolates of Pneumocystis carinii

The DNA sequences of a portion of the 5-enolpyruvyl shikimate phosphate synthase domain of the arom gene, encoding the pentafunctional AROM protein, were determined from isolates of Pneumocystis carinii from five mammalian host species (rat, human, ferret, rabbit and mouse). High levels of genetic divergence were found among P. carinii derived from different host species, 7-22% at the DNA sequence level, and 7-26% at the derived amino acid sequence level. Two separate and distinct sequences were isolated from infected ferret lungs. Low levels of divergence were seen in human-derived organisms.

The cloning and characterization of the arom gene of Pneumocystis carinii

The arom gene, encoding a single polypeptide that catalyses five consecutive steps of the pre-chorismate aromatic amino acid biosynthetic pathway, has been cloned from the opportunistic pathogen Pneumocystis carinii. There is a single open reading frame of 4788 bp which includes an intron of 45 bp that does not introduce a stop codon into the sequence. Thus, the derived amino acid sequence consists of 1581 residues, which is highly homologous to all fungal AROM proteins studied to date. These data support the view that P. carinii is a fungus and imply that its aromatic amino acid biosynthesis is conventionally organized.

Antiulcer and gastric secretory activity of N-phthaloyl gamma-aminobutyric acid

N-Phthaloyl gamma-aminobutyric acid, a new gamma-aminobutyric acid derivative synthesized in this laboratory, has been found to possess anticonvulsant, antinociceptive and antistress activities. Effects of this derivative on gastric lesions induced by aspirin and ethanol were studied in rats. N-Phthaloyl gamma-aminobutyric acid significantly inhibited both aspirin and alcohol ulceration. The ED50 in each case being 76.34 and 43.65 mg/kg i.p. respectively. The volume of gastric acid secretion was diminished but gastric mucus secretion was significantly enhanced. The antiulcer effect was blocked by bicuculline and 3-mercaptopropionic acid. We conclude that (a) N-phthaloyl gamma-aminobutyric acid possesses antiulcer activity (b) the new derivative is probably a non-specific gamma-aminobutyric acid receptor agonist (c) the observed activity may be due to a mucoprotective action.

Pneumocystis carinii shows DNA homology with the ustomycetous red yeast fungi

Pneumocystis carinii causes life-threatening pneumonia in T-lymphocyte-immunodeficient subjects in transplant and oncology units or with acquired immune deficiency syndrome (AIDS). Recent DNA homology studies show P. carinii to be a fungus. To investigate the biology and epidemiology of this parasite further, we elected to determine for it a more precise taxonomic assignment within the fungal kingdom. We screened a wide range of organisms representing the major orders of fungi using DNA amplification and subsequently sequenced a portion of the mitochondrial gene encoding the large subunit ribosomal RNA. Our data show that the opportunistic pulmonary pathogen P. carinii is closely related to the ustomycetous red yeast fungi, a group which includes organisms that are extensively distributed throughout the environment and which release many widely dispersed airborne spores.

Quantification of the detection of Pneumocystis carinii by DNA amplification

We have developed a highly specific and sensitive technique for the detection of Pneumocystis carinii DNA using DNA amplification by the polymerase chain reaction (PCR). PCR products are detected by agarose gel electrophoresis and Southern hybridization to an oligonucleotide probe. Here we report the calibration of parasite numbers with amplification and hybridization signals and show that we can detect P. carinii to a lower limit of one to two organisms. The quantification of this diagnostic technique allows us to establish the number of organisms in a clinical sample which correspond to pneumocystis pneumonia or to sub-clinical pulmonary colonization.