Proteoglycans in predentin: the last 15 micrometers before mineralization

Small leucine-rich proteoglycans (SLRPs) regulate extracellular matrix organization. In order to investigate the distribution and potential functions of decorin, biglycan (BGN), and fibromodulin (3 SLRPs, potentially related to dentinogenesis), we performed light and electron immunochemistry on teeth from rats, and on wild-type and biglycan knockout mice (BGN KO). Immunohistochemical data demonstrate that chondroitin sulfate/dermatan sulfate (CS/DS) and keratan sulfate (KS) distributions displayed reverse gradients in predentin. The decrease of CS/DS labeling from the proximal to the distal predentin contrasted with the sharp decorin increase observed in the distal predentin near the predentin/dentin transition, an effect possibly attributable to the deglycosylation action of stromelysin-1. In contrast, BGN concentration was apparently constant throughout the whole predentin. Additional immunolabelings showed, for the first time, the presence of fibromodulin in predentin. Compared with the wild-type mouse, the mean diameter of collagen fibrils in the BGN KO was smaller in the proximal predentin but larger in the central and distal predentin, the metadentin was broader, and the dentin mineralization appeared altered and heterogeneous. Altogether, our data suggest an important role for BGN in dentin formation and mineralization.

The DNA sequence and analysis of human chromosome 6

Chromosome 6 is a metacentric chromosome that constitutes about 6% of the human genome. The finished sequence comprises 166,880,988 base pairs, representing the largest chromosome sequenced so far. The entire sequence has been subjected to high-quality manual annotation, resulting in the evidence-supported identification of 1,557 genes and 633 pseudogenes. Here we report that at least 96% of the protein-coding genes have been identified, as assessed by multi-species comparative sequence analysis, and provide evidence for the presence of further, otherwise unsupported exons/genes. Among these are genes directly implicated in cancer, schizophrenia, autoimmunity and many other diseases. Chromosome 6 harbours the largest transfer RNA gene cluster in the genome; we show that this cluster co-localizes with a region of high transcriptional activity. Within the essential immune loci of the major histocompatibility complex, we find HLA-B to be the most polymorphic gene on chromosome 6 and in the human genome.

Comparison of 0.2% ropivacaine and 0.25% bupivacaine for axillary brachial plexus blocks in paediatric hand surgery

BACKGROUND

The purpose of this study was to compare the use of ropivacaine 0.2% with bupivacaine 0.25% for axillary brachial plexus block in children undergoing hand surgery.

METHODS

In a double-blind, randomized study, 35 children undergoing hand surgery received axillary brachial plexus blocks with 0.5 ml.kg-1 of either 0.2% ropivacaine or 0.25% bupivacaine. Pain scores were noted at 0, 3, 6, 12 and 24 h after surgery. The time to first dose of codeine phosphate and the total doses of all analgesics given were recorded.

RESULTS

There was no significant difference between the two groups in pain scores, the time to first dose of codeine phosphate or in analgesic requirements in the first 24 h.

CONCLUSIONS

Ropivacaine 0.2% is as effective as bupivacaine 0.25% for axillary brachial plexus blocks in children undergoing hand surgery.

The dentino-enamel junction revisited

The dentino-enamel junction is not an simple inert interface between two mineralized structures. A less simplistic view suggests that the dentino-enamel junctional complex should also include the inner aprismatic enamel and the mantle dentin. At early stages of enamel formation, fibroblast growth factor (FGF)-2 is stored in and released from the inner aprismatic enamel, possibly under the control of matrix metalloproteinase (MMP)-3. The concentration peak for MMP-2 and -9 observed in the mantle dentin coincided with a very low labeling for TIMP-1 and -2, favoring the cross-talk between mineralizing epithelial and connective structures, and as a consequence the translocation of enamel proteins toward odontoblasts and pulp cells, and vice versa, the translocation of dentin proteins toward secretory ameloblasts and cells of the enamel organ. Finally, in X-linked hypophosphatemic rickets, large interglobular spaces in the circumpulpal dentin were the major defect induced by the gene alteration, whereas the mantle dentin was constantly unaffected. Altogether, these data plead for the recognition of the dentino-enamel junctional complex as a specific entity bearing its own biological characteristics.

Accuracy and precision of population estimates of Verticillium dahliae on growth media in quantitative soil assays

Verticillium dahliae Kleb. is a serious pathogen of many plant species. Growth media used to measure population density of V. dahliae in soil were evaluated for high recovery of the pathogen, as well as accuracy and precision of population estimates from naturally and artificially infested sandy loam soil using the soil dilution method. Recovery of V. dahliae from naturally infested field soil was highest on soil pectate Tergitol agar (SPT), soil extract agar + sodium polypectate (SEAP), modified pectate agar (MPA), potato dextrose agar + streptomycin sulphate (PDAS), and Talboys' prune lactose agar (TPA); however, PDAS and TPA were overgrown with contaminating fungi, making enumeration difficult. Use of SPT medium resulted in the most precise population estimate with a standard error (SE) of 12.6% of the mean followed by use of pectate agar (PA) (SE = 14.8%) and SEAP (SE = 19.1%). Ethanol, biotin, and Dox salts enhanced recovery of V. dahliae from naturally infested soil, but combining Dox salts with ethanol and biotin significantly reduced population density. Soil extract had no significant effects on population density. Accuracy of V. dahliae population estimates from sterile artificially inoculated soil was highest on modified soil extract agar (MSEA) (64%) followed by SPT (58%). However, accuracy of V. dahliae population estimates from nonsterile artificially inoculated soil was highest on SPT (36%). Soil extract is not an essential ingredient and biotin may increase recovery of V. dahliae from soil.Key words: Verticillium dahliae, verticillium wilt, population density, recovery, accuracy, precision.

High risk of surgical intervention in hereditary pancreatitis

Background

The aim of the study was to quantify the risk of surgical intervention in families with hereditary pancreatitis referred to the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC).

Methods

Recruitment to EUROPAC started in 1997; families were considered if two or more members had chronic pancreatitis of unknown aetiology. Families were tested for protease serine 1 (PRSS1) mutations using polymerase chain reaction restriction digestion, sequencing the PRSS1 gene-screened negative families. Clinical information about surgical intervention was obtained from family members and referring clinicians, and the cumulative incidence of surgical intervention in the N291 and R122H mutation groups was determined with the Kaplan–Meier method.

Results

Forty-four families had the R122H mutation, 21 the N291 mutation, and 31 were negative for both. Some 14 (35 per cent) of 40 patients (median age 26·5 (95 per cent confidence interval (c.i.) 21·5–36·3) years) with the N291 mutation had an operative procedure for complications of pancreatitis, compared with 21 (25 per cent) of 83 patients (median age 24 (95 per cent c.i. 13·8–35·8) years) with the R122H variant. This resulted in a cumulative lifetime risk for surgical intervention of 0·6 (95 per cent c.i. 0·5–0·8) for the R122H mutation and 0·6 (0·5–0·8) for the N291 mutation (P = 0·11, log rank test).

Conclusion

Hereditary pancreatitis carries a significantly increased risk of surgical intervention in this cohort of patients, which equates to an estimated lifetime risk of around 60 per cent. The risk of surgery appears to be independent of PRSS1 mutation type.

A systematic approach to erectile dysfunction in the cardiovascular patient: a Consensus Statement--update 2002

Sexual activity is no more stressful to the heart when compared with a number of other natural daily activities, e.g. walking one mile on the level in 20 minutes. The cardiac risk of sexual activity in patients diagnosed with cardiovascular disease is minimal in properly assessed and advised patients. Erectile dysfunction (ED) is extremely common, affecting over half of men aged 40-70 years, and increases in frequency with age. ED and cardiovascular disease share many of the same risk factors and commonly coexist. ED in the otherwise asymptomatic man may be a marker for underlying coronary artery disease. ED in the diagnosed cardiovascular patient should be identified by routine questioning in general practice. Modern therapies can restore a sexual relationship in the majority of patients with ED and can lead to a substantial improvement in quality of life. The majority of patients assessed to be at low or intermediate cardiac risk, as defined later in this paper, can be effectively managed in primary care. Primary care treatment for ED in patients defined as high risk can be initiated following a specialist opinion and/or confirmation that the patient's cardiovascular condition is stabilised. There is no evidence that currently licensed treatments for ED add to the overall cardiovascular risk in patients with or without diagnosed cardiovascular disease. If one form of therapy is not effective, follow-up will identify the need for alternative approaches. The pro-active management of ED in the cardiovascular patient provides an ideal and effective opportunity to address other cardiovascular risk factors and improve treatment outcomes.

Prime-boost: the way forward for recombinant vaccines against apicomplexan parasites. A Theileria perspective

A good CD8+ response is required for immunity to many intracellular pathogens. Traditional antigen delivery using isolated sub-units or killed pathogens and adjuvant stimulates strong antibody responses but weak T-cell reactivity. Attenuated vaccines are usually more effective. The prime-boost delivery system based on immunisation with a naked DNA antigen-gene construct followed by boosting with an attenuated vaccinia virus expressing the same antigen is proving to be a powerful way to stimulate antigen-specific CD8 responses. Success using single epitopes is possible in malaria and we believe this approach holds much promise for other apicomplexan parasites such as Theileria spp.

Cloning, expression and characterization of the CHO cell elongating factor (Cef) from Vibrio cholerae O1

CHO cell-elongating factor (Cef) is a recently identified putative virulence factor of Vibrio cholerae. Our previous studies show that this 85 kDa protein elongates CHO cells, causes fluid accumulation in suckling mice and has esterase activity. In this study, the cef gene was cloned in Escherichia coli using a yeast vector and subsequently expressed in the yeast Pichia pastoris. The cef genes from V. cholerae candidate vaccine strains JBK 70 and CVD 103-HgR were sequenced and found to be nearly identical (100 and 99.9% respectively) with an open reading frame (ORF) from the published sequence of V. cholerae N16961. Cloned toxin was purified to homogeneity in 3 steps using anion exchange, hydrophobic interaction and gel filtration chromatography. The size of cloned Cef on SDS-PAGE gels was 114 kDa. The increased size was probably due to glycosylation by the yeast since cloned protein reacted strongly with a glycoprotein stain. The cloned protein could not be directly sequenced, but when treated with trypsin, yielded a protein fragment with an amino acid sequence that matched the sequence predicted for the Cef protein. The purified cloned protein had esterase and CHO cell activity, but no suckling mouse activity.

A double-blind, parallel-group study of amlodipine versus long-acting nitrate in the management of elderly patients with stable angina

Ninety-seven elderly patients with stable angina were included in a 28-week, randomized, double-blind, parallel-group comparison of amlodipine 5-10 mg and isosorbide mononitrate 25-50 mg once daily. The total exercise time, as limited by angina, was recorded together with the median incidence per week of angina attacks and glyceryl trinitrate consumption. Safety was assessed by adverse event frequency, measurement of vital signs and laboratory parameters, and quality of life. At the final visit, the total exercise time was significantly greater relative to baseline with amlodipine than isosorbide mononitrate (final/baseline difference: 112.2 vs. 32.2, p = 0.016). There were no statistically significant differences between the groups in relation to the incidence of adverse events. Once daily amlodipine provides significantly better control of stable angina than isosorbide mononitrate in this elderly population.

Proteoglycans in dentinogenesis

The predominant proteoglycans present in predentin and dentin are the chondroitin-sulphate-rich decorin and biglycan and the keratan-sulphate-rich lumican and fibromodulin. These are small, interstitial, leucine-rich proteoglycans which have recently been shown to exist in gradients across the predentin. Antibodies recognizing chondroitin sulphate show a decreasing gradient from the pulpal aspect toward the mineralizing front, the converse being true for keratan sulphate. Antidecorin shows an increase toward the mineralization front. Evidence from biochemical, autoradiographic, and immunohistochemical studies implies that such changes may be brought about by gradients of metalloproteinases. This offers the possibility that the proteoglycans organize the collagen network for receipt of phosphoproteins and phospholipids, the former being evident only at the onset of dentin formation. The suggestion is raised that glycosaminoglycan-depleted leucine-rich protein cores act as sequester points for receipt of phosphoproteins in particular. The rigid, spatially oriented glycosaminoglycan chains on decorin and biglycan are known to bind calcium and may feature directly in mineral initiation.

Recurrent bile duct stones after transduodenal sphincteroplasty

BACKGROUND

Transduodenal sphincteroplasty (TDS) offers permanent prophylaxis against further stones in the common bile duct (CBD) by allowing continuous free efflux of bile from the papilla.

PATIENTS AND RESULTS

In a personal series of 267 consecutive operations, four patients underwent further treatment for recurrent CBD stones during a median follow-up of 12 years. Three of them received Roux-en-Y biliary diversion and had no further symptoms; the fourth patient remains well four years after endoscopic extraction of stones.

DISCUSSION

Recurrent stone formation is rare after an adequate TDS and probably reflects retained food debris within the CBD. Initial treatment may be endoscopic, but biliary diversion is needed for those with recurrent symptoms.

The potential of 19F NMR spectroscopy for rapid screening of cell cultures for models of mammalian drug metabolism

The use of microbial cultures as a complementary model for mammalian drug metabolism has been well established previously. Here is a preliminary investigation into the potential of 19F NMR spectroscopy as a rapid screening tool to quantify the biotransformations of fluorine-containing model drugs. Biotransformations of three model drugs in 48 taxonomically diverse organisms were measured by acquiring 19F NMR spectra at 376 MHz. The presence of fluorine in the molecules allowed rapid, simultaneous detection of over 20 biotransformation products without sample pretreatment, chromatography, mass spectrometric techniques or the use of radiolabelled substrates. The detection limit at 376 MHz using 5 mm NMR tubes was ca. 0.3 microg ml(-1) using a typical analysis time of 20 min per sample. With the recent advent of flow injection NMR technology, analysis time of 5 min could be achieved with less sample. This approach may be used to develop fast small-scale microbial screens for the biosynthesis of metabolite standards and production of novel drug analogues, whilst also having a role in reducing animal experiments needed to identify animal and human metabolites of fluorinated xenobiotics.

Prevalence and risk factors for hepatitis C virus infection at an urban Veterans Administration medical center

This study was designed to determine the seroprevalence and risk factors for hepatitis C virus (HCV) infection in veterans. Anti-HCV testing was performed in 1,032 patients and a questionnaire regarding sociodemographic characteristics and potential risk factors was administered. Adjusted prevalence of unique HCV-positive patients using outpatient services was 17.7% (95% confidence interval [CI] 17.2%, 18.2%). The following risk factors were associated with HCV infection: a history of injection drug use (IDU), receipt of blood transfusion prior to 1992, history of tattoo (odds ratio [OR], 2.93; 95% CI, 1.70-5.08), combat job as a medical worker (OR, 2.68; 95% CI, 1.25-5.60), history of incarceration over 48 hours (OR, 2.56; 95% CI, 1.52-4.32), greater than 15 lifetime sexual partners (OR, 1.61; 95% CI, 0.94-2.76) and sexual relations with a prostitute (OR, 0.46; 95% CI, 0.25-0.82). We concluded that HCV is common in veterans. Risk factors independently associated with infection are IDU, prior transfusion, prior tattoo, combat medical work, incarceration, and multiple opposite sex partners. Infection with HCV among veterans is strongly associated with traditional risk factors for infection and less strongly associated with combat-related risk.