Development of a novel antimicrobial-releasing glass ionomer cement functionalized with chlorhexidine hexametaphosphate nanoparticles

Background

Glass ionomer cements (GICs) are a class of dental biomaterials. They have a wide range of uses including permanent restorations (fillings), cavity linings, fissure sealants and adhesives. One of the most common reasons for replacing a dental restoration is recurrent bacterial tooth decay around the margins of the biomaterial. Therefore, a dental biomaterial which creates a sustained antimicrobial environment around the restoration would be of considerable clinical benefit. In this manuscript, the formulation of a GIC containing novel antimicrobial nanoparticles composed of chlorhexidine hexametaphosphate at 1, 2, 5, 10 and 20% powder substitution by mass is reported. The aim is to create GICs which contain chlorhexidine-hexametaphosphate nanoparticles and characterize the nanoparticle size, morphology and charge and the release of chlorhexidine and fluoride, tensile strength and morphology of the GICs.

Results

The GICs released chlorhexidine, which is a broad spectrum antimicrobial agent effective against a wide range of oral bacteria, over the duration of the experiment in a dose-dependent manner. This was not at the expense of other properties; fluoride release was not significantly affected by the substitution of antimicrobial nanoparticles in most formulations and internal structure appeared unaffected up to and including 10% substitution. Diametral tensile strength decreased numerically with substitutions of 10 and 20% nanoparticles but this difference was not statistically significant.

Conclusion

A series of GICs functionalized with chlorhexidine-hexametaphosphate nanoparticles were created for the first time. These released chlorhexidine in a dose-dependent manner. These materials may find application in the development of a new generation of antimicrobial dental nanomaterials.

Comparative analysis of an intestinal strain of Bifidobacterium longum and a strain of Bifidobacterium animalis subspecies lactis in Cheddar cheese

Bifidobacteria cultures were incorporated into Cheddar cheeses to conduct a comparative analysis between the commercially available strain Bifidobacterium animalis ssp. lactis Bb-12 and the wild-type intestinal isolate, Bifidobacterium longum DJO10A. They were incorporated as starter adjuncts in separate vats and as a mixed culture, and survival through manufacturing and cheese ripening was assessed. For cheese using only Bb-12, the cells may have grown during cheese manufacture as 133% of the inoculum was incorporated into the cheese, resulting in 8.00 log cfu/g. Counts remained high during ripening showing less than 1 log decrease over a 12-mo period. For cheese using a mixed culture of Bb-12 and DJO10A, both strains were incorporated at much lower levels: 3.02 and 1.11%, respectively. This resulted in cheese with 6.00 and 5.04 log cfu/g for Bb-12 and DJO10A, respectively. Bifidobacteria survival rates were low, most likely due to the moisture of the cheese being below 38%. The Bb-12 demonstrated almost 100% viability during ripening. Numbers of DJO10A started to decline after 2 mo of ripening and dropped below the level of detection (2 log cfu/g) after 4.5 mo of ripening. Neither DJO10A nor Bb-12 fortified cheeses produced detectable amounts of organic acids during ripening other than lactic acid, indicating the lack of detectable metabolic contribution from bifidobacteria during cheese production and ripening such as production of acetic acid. To determine if sublethal stresses could improve the viability of DJO10A, 2 more vats were made, 1 with DJO10A exposed to sublethal acid, cold, and centrifugation stresses, and 1 exposed to none of these stresses. Although stress-primed DJO10A survived cheese manufacture better, as 72.8% were incorporated into the cheese compared with 41.1% of the unprimed, the statistical significance of this difference is unknown. In addition, the difference in moisture levels in the cheese cannot be excluded as influencing this difference. However, the rate of decline during ripening was similar for both. After 6 mo of ripening, cell counts in cheese were 4.68 and 4.24 log cfu/g for primed and unprimed cultures, respectively. These results suggest that whereas priming bifidobacteria with sublethal stresses before incorporation in a cheese fermentation may improve the number of viable cells that get incorporated into the cheese, it does not affect viability during cheese ripening.

Differential adhesion of Streptococcus gordonii to anatase and rutile titanium dioxide surfaces with and without functionalization with chlorhexidine

The majority of dental implants are composed primarily of titanium and have an outer layer of titanium dioxide. Crystalline titanium dioxide most commonly exists in one of the two structures, anatase and rutile, and both of these have been observed on commercially available dental implants. Early implant failure can be associated with postoperative infection due to implant contamination during or immediately after surgery. The impetus of this study was to investigate whether functionalization of anatase and rutile titanium dioxide surfaces with chlorhexidine-reduced subsequent colonization of the surface by Streptococcus gordonii. Exposure to 100 mg x L(-1) chlorhexidine for 60 s resulted in a fivefold reduction in S. gordonii coverage on anatase and a twofold reduction on rutile. This may be related to a preferential adsorption of chlorhexidine to anatase compared with rutile. The reduction in bacterial coverage was not due to desorption of chlorhexidine into solution. More bacteria were observed on anatase than rutile surfaces without chlorhexidine functionalization, indicating that crystal structure may have a significant effect on bacterial colonization. In conclusion, functionalization with chlorhexidine reduced bacterial coverage on titanium dioxide surfaces, and anatase surfaces may be more amenable to such treatment than rutile.

Teaching dental pain with and without underlying oral physiology: learning implications

This study investigated whether teaching undergraduate dental students the diagnosis and management of acute dental pain alongside the underpinning oral physiology helped them to understand the topic better than teaching them acute dental pain as a separate entity. Each of three clinical years of dental students at the same dental school was taught in two groups. Each group was taught the signs/symptoms of five acute dental pain conditions by the same member of the staff. However, the teaching for one group of students in each year reminded the students about the physiology that underpinned the clinical symptoms. One week later, the students completed an open-ended questionnaire that required them to list signs/symptoms of the five dental pain conditions. For each year of dental students that was examined, the mean student marks were significantly higher (p<0.05) for those who were taught dental pain and the underlying physiology compared with students who were only taught dental pain as a stand-alone subject. This suggests that integrating biomedical science and clinical teaching is beneficial.

A survey of undergraduate education in dental implantology in UK dental schools

The aim of this study was to ascertain knowledge on current teaching of implant dentistry in the undergraduate curriculum of Dental Schools in the UK. Information on the teaching modalities, including year of introduction of implant dentistry into undergraduate curriculum, departments involved in teaching, format of teaching, use of adjunctive teaching aids, and types of implant systems used in undergraduate teaching was collected by means of a questionnaire, which was sent to all undergraduate dental schools in the UK. Based on a 100% response rate, the findings indicate that all dental schools in the UK reported that they included dental implantology in their undergraduate curriculum; however there were marked variations in the content and delivery of the teaching.

Comparative genomic analysis of the gut bacterium Bifidobacterium longum reveals loci susceptible to deletion during pure culture growth

Background

Bifidobacteria are frequently proposed to be associated with good intestinal health primarily because of their overriding dominance in the feces of breast fed infants. However, clinical feeding studies with exogenous bifidobacteria show they don't remain in the intestine, suggesting they may lose competitive fitness when grown outside the gut.

Results

To further the understanding of genetic attenuation that may be occurring in bifidobacteria cultures, we obtained the complete genome sequence of an intestinal isolate, Bifidobacterium longum DJO10A that was minimally cultured in the laboratory, and compared it to that of a culture collection strain, B. longum NCC2705. This comparison revealed colinear genomes that exhibited high sequence identity, except for the presence of 17 unique DNA regions in strain DJO10A and six in strain NCC2705. While the majority of these unique regions encoded proteins of diverse function, eight from the DJO10A genome and one from NCC2705, encoded gene clusters predicted to be involved in diverse traits pertinent to the human intestinal environment, specifically oligosaccharide and polyol utilization, arsenic resistance and lantibiotic production. Seven of these unique regions were suggested by a base deviation index analysis to have been precisely deleted from strain NCC2705 and this is substantiated by a DNA remnant from within one of the regions still remaining in the genome of NCC2705 at the same locus. This targeted loss of genomic regions was experimentally validated when growth of the intestinal B. longum in the laboratory for 1,000 generations resulted in two large deletions, one in a lantibiotic encoding region, analogous to a predicted deletion event for NCC2705. A simulated fecal growth study showed a significant reduced competitive ability of this deletion strain against Clostridium difficile and E. coli. The deleted region was between two IS30 elements which were experimentally demonstrated to be hyperactive within the genome. The other deleted region bordered a novel class of mobile elements, termed mobile integrase cassettes (MIC) substantiating the likely role of these elements in genome deletion events.

Conclusion

Deletion of genomic regions, often facilitated by mobile elements, allows bifidobacteria to adapt to fermentation environments in a very rapid manner (2 genome deletions per 1,000 generations) and the concomitant loss of possible competitive abilities in the gut.

The effects of polishing methods on surface morphology, roughness and bacterial colonisation of titanium abutments

Bacterial colonisation of exposed implant and abutment surfaces can lead to peri-implantitis, a common cause of oral implant failure. When an abutment becomes exposed in the oral environment the typical recommendation is to debride it, to obtain a smoother surface which might be expected to reduce bacterial colonisation. The aim of this study was to evaluate, in vitro, a conventional polishing protocol (PP1) and a simplified polishing protocol (PP2), suggested to have advantages over PP1. The surface morphology and roughness of titanium abutments were characterised at each stage of polishing, and adhesion of oral bacteria was evaluated, using atomic force microscopy, environmental scanning electron microscopy and optical profilometry. PP1 and PP2 methodologies resulted in indistinguishable surface finishes, with fewer scratches than the unmodified surface, and equal roughness values. PP2 resulted in less disruption and less removal of surface material. Early biofilm formation by Streptococcus mutans was reduced on surfaces polished using PP2, but not PP1. Biofilms of Actinomyces naeslundii were more extensive on polished abutment surfaces. Simplified protocol PP2 may be preferable to conventional protocol PP1, since less material is removed, and there is less chance of rough areas remaining. Polishing, however, does not necessarily reduce oral bacterial colonisation.

An in vitro investigation of the effect of some analgesics on human enamel

The sale of over-the-counter pain relief medication has increased dramatically in recent years, and typically amounts to several hundred thousands of pounds per year in the UK. Many soluble analgesic preparations contain citric acid, and it has been suggested that these formulations may cause dental erosion. The aim of this study was to investigate the effect of some over-the-counter analgesics on tooth surface loss from human enamel. Six commonly available analgesics were chosen for this study and the effect of immersing unerupted human enamel was examined using non-contact optical profilometry. Two of the six analgesics investigated caused no detectable erosion (Boots soluble aspirin and Anadin Extra). Three caused statistically significant enamel erosion, but this was very slight and is thought to be clinically insignificant (Alka Seltzer, Panadol and Solpadeine). Only one analgesic caused possible potentially clinical significant enamel erosion. Further studies are needed to determine whether Aspro causes clinically significant enamel erosion.

The effect of a range of disinfectants on the dimensional accuracy and stability of some impression materials

Disinfection of dental impressions should be considered as a routine procedure in dental surgeries and dental laboratories. Disinfectants can have deleterious effects on some properties of impression materials. The aim of this study was to evaluate the dimensional accuracy and dimensional stability of a model dental stone, reproduced from five commonly used impression materials (Aquasil soft putty/Aquasil Ultra LV; Aquasil Monophase; Aquasil Ultra Heavy; Impregum F and Provil putty/Provil Light CD wash) retained by their adhesives in acrylic resin trays and exposed to three disinfectant solutions (Perform ID; Haz-Tabs and MD 520). Two hundred models were used to investigate the effect of the three disinfectants on the dimensional accuracy of the five impression materials. Five impressions were taken for each impression material for each disinfection treatment group. Measurements were carried out using a High Precision Reflex Microscope. All materials demonstrated a percentage change in dimensions when subjected to no disinfection when compared to the brass master die and all materials demonstrated a percentage change in dimension when subjected to the different disinfection procedures. The results of this study have demonstrated that for all of the materials investigated, the changes in dimensional stability were small in the order of microns. These changes may however be of clinical significance for procedures requiring a high degree of accuracy, for example fixed prosthodontics. The materials respond differently depending on the disinfectant used and it may therefore be appropriate that manufacturers recommend the use of particular disinfectants for their products in order to ensure optimum dimensional accuracy and stability.

An in vitro investigation of the effect of the addition of untreated and surface treated silica on the transverse and impact strength of poly(methyl methacrylate) acrylic resin

Silica is a commonly used filler in dental materials and as a reinforcing agent in industry. The aim of this study was to further investigate the effect of the addition of untreated and a novel surface treated silica on the transverse bend and impact strength of acrylic resin denture base material. It was hypothesized that the silica/resin composite materials would have an improved flexural and impact strength than the conventional heat-cured acrylic resin. Three types of untreated and two of treated silica powder were used in this study. The range of percentages used were 1%, 0.5%, 0.2%, 0.1%. The treated particles were coated with hexamethyldisilazane or dimethyldichloridesilazane. Conventional heat cured acrylic resin was used as a control. The modulus of rupture for all groups of acrylic resin containing silica was significantly lower than for the control. The modulus of elasticity was not significantly greater than the control group. For the impact strength statistical analysis revealed a significant difference between the groups. There was a nonsignificant increase in the impact strength for specimens compared to the control. In conclusion the addition of silica to poly(methyl methacrylate) denture base materials did not produce a significant improvement in the transverse bend or impact strength compared to conventional heat-cured acrylic resin. The incorporation of untreated and surface treated silica cannot be recommended as a method of reinforcement.

Lesion of thalamic centromedian--parafascicular complex after chronic deep brain stimulation

A patient with PD who exhibited disabling tremor and prominent dyskinesia underwent deep brain stimulation (DBS) of the left thalamic ventral intermediate nucleus. The electrode migrated and was replaced but with suboptimal clinical response. Two years later, postmortem analysis found the second electrode tip had entered the thalamic centromedian-parafascicular complex. There was a small thalamotomy and cell loss exceeding that found in PD. Thalamic damage may occur in association with DBS for PD.

Screening of intestinal microflora for effective probiotic bacteria

Increasing consumer awareness of health-promoting intestinal bacteria has fueled the addition of viable probiotic bacteria as functional ingredients in certain foods. However, to effectively market the enhanced attributes of these foods, the added probiotic bacteria need to have scientific credibility. The scientific rationale for using many of the strains of probiotic bacteria currently on the market is weak. Furthering the current understanding of what features a bacterium needs to have for effective probiotic functionality will enable the selection of strains with a more credible scientific rationale. To screen for effective strains, one must understand the microbial diversity in the intestines of healthy individuals. The advent of molecular tools has greatly enhanced our ability to accomplish this. These tools comprise genetic fingerprinting, specific probes, molecular speciation, and techniques for the in situ analysis of specific microbial groups in the intestine. This review will detail these scientific approaches and how their impact will improve criteria for selection of probiotic bacteria.

Isolation, characterization, and influence of native, nonstarter lactic acid bacteria on Cheddar cheese quality

To determine whether adventitious nonstarter lactic acid bacteria (NSLAB) might affect cheese flavor and quality, we studied a population of NSLAB present in 30 premium quality Cheddar cheeses (3-mo ripened) produced at a commercial facility in the United States. DNA fingerprinting analysis with a sensitive strategy for arbitrary priming polymerase chain reaction showed that 75 isolates corresponded to at least 18 distinct nonstarter organisms. According to ribotype database comparisons of representatives from the 18 groups, 9 matched Lactobacillus (closest to paracasei species), 8 matched Streptococcus thermophilus, and 1 matched to a Lactococcus species. This finding indicated that among the 75 NSLAB isolates, Lactobacillus made up 64%, S. thermophilus 32%, and Lactococcus 4%. Isolates representing 11 NSLAB groups were characterized for protease, peptidase, and diacetyl production. Based on this phenotypic analysis, two Lactobacillus isolates were evaluated as adjuncts in Cheddar cheese. All of the NSLAB identified from the adjunct cheese at 3 mo by DNA fingerprinting consisted of the adjunct lactobacilli, showing that the adjunct strains predominated throughout the early stages of ripening. The impact of adjunct lactobacilli was evident after 6 mo when free amino acids significantly increased and sensory scores improved in adjunct cheese as compared with a control cheese. The largest impact was found in adjunct cheese containing a blend of both lactobacilli strains. These results show that certain adventitious NSLAB positively contribute to flavor development.

Identification of a gene cluster encoding Krebs cycle oxidative enzymes linked to the pyruvate carboxylase gene in Lactococcus lactis ssp. lactis C2

We identified a 14-kb pyruvate carboxylase gene-containing fragment from a lactococcal C2-lambda phage genomic library. Downstream of the pyruvate carboxylase gene-containing fragment, a gene cluster coding for open reading frames displaying extensive homology to citrate synthase, aconitase, and a truncated isocitrate dehydrogenase was identified. However, the truncation was shown to have occurred during the cloning by two noncontiguous Sau3AI fragments ligating together. The lactococcal citrate synthase gene consisted of 1323 bp and encoded a 441-amino acid citrate synthase protein. The lactococcal aconitase gene was 2544 bp and encoded an 848-amino acid protein. Corresponding to the complete citrate synthase gene, citrate synthase activity was detected in Lactococcus lactis ssp. lactis C2. Isocitrate dehydrogenase activity was found to be missing in Lactococcus lactis C2, suggesting that the gene may be incomplete or is not expressed, resulting in a requirement for glutamic acid in lactococci.

Methods for analysis of the intestinal microflora

The concept of probiotics has been around for about 100 years. Yet its impact on human nutrition is still an emerging concept. Lack of convincing scientific validation for the efficacy of any ingested probiotic bacterium on intestinal health, has been a major reason for the low impact of probiotics on human nutrition. Obtaining positive scientific validation requires the use of suitable probiotic strains and also the necessary tools to monitor the performance of these bacteria in the intestines of individuals. To date, selection of strains for probiotic purposes has not been based on a scientific directed approach, primarily because it is not yet fully known what specific traits a desirable probiotic strain should possess. Filling this knowledge void will depend largely on furthering our understanding of the human intestinal ecosystem and the functional role of specific bacteria for intestinal health. Traditional approaches for studying this ecosystem have provided a good foundation in this knowledge base. Complementation of the traditional approaches with the emergence of sophisticated molecular tools shows enormous promise for obtaining the necessary insight into the intestinal microflora. This review will cover the traditional methodologies which have been used to analyze the human intestinal microflora. It will also reveal the development of modern molecular approaches for studying the diversity and phylogeny of its flora, and the rapid molecular tools for monitoring the presence of specific strains in the intestine. Finally, it will address the advent of in situ analysis of individual microbial cells, which promises to provide tremendous advances in our understanding of the microflora and their metabolic activities in the human intestine.

Classification of a bacterial isolate, from pozol, exhibiting antimicrobial activity against several gram-positive and gram-negative bacteria, yeasts, and molds

A bacterial isolate, designated CS93, capable of producing a broad-spectrum antimicrobial compound(s) effective against gram-positive and gram-negative bacteria, yeasts, and molds was isolated from pozol, a fermented maize product. This strain was phenotypically similar to another pozol isolate that was previously designated as Agrobacterium azotophilium by other investigators. By using biochemical, phenotypic, and 16S rRNA sequence analysis, both pozol isolates were identified as members of the genus Bacillus, possibly a variant of Bacillus subtilis. While the antimicrobial compound(s) was initially produced only on a solid medium, parameters were identified for production in broth. The compound(s) was heat stable (121 degrees C for 15 min), exhibited activity over a wide pH range (pH 3 to pH 11), and was inactivated by pronase E. The antimicrobial compound(s) was bactericidal and bacteriolytic against Escherichia coli V517, bacteriostatic against Micrococcus luteus, and fungistatic against Saccharomyces cerevisiae. The inhibitory compound(s) could possibly serve as a food biopreservative.

Characterization of AbiR, a novel multicomponent abortive infection mechanism encoded by plasmid pKR223 of Lactococcus lactis subsp. lactis KR2

The native lactococcal plasmid pKR223 encodes two distinct phage resistance mechanisms, a restriction and modification (R/M) system designated LlaKR2I and an abortive infection mechanism (Abi) which affects prolate-headed-phage proliferation. The nucleotide sequence of a 16,174-bp segment of pKR223 encompassing both the R/M and Abi determinants has been determined, and sequence analysis has validated the novelty of the Abi system, which has now been designated AbiR. Analysis of deletion and insertion clones demonstrated that AbiR was encoded by two genetic loci, separated by the LlaKR2I R/M genes. Mechanistic studies on the AbiR phenotype indicated that it was heat sensitive and that it impeded phage DNA replication. These data indicated that AbiR is a novel multicomponent, heat-sensitive, "early"-functioning Abi system and is the first lactococcal Abi system described which is encoded by two separated genetic loci.

Use of chemical mutagenesis for the isolation of food grade beta-galactosidase overproducing mutants of bifidobacteria, lactobacilli and Streptococcus thermophilus

A classical chemical mutagenesis protocol was evaluated for increasing beta-galactosidase production by probiotic bacteria to improve their potential to treat symptoms of lactose malabsorption in humans. Two Bifidobacterium species (B. breve and B. longum) and one strain each of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus were tested by a single exposure to two chemical mutagens, ethyl methanesulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). To screen for beta-galactosidase (beta-gal) overproducing mutants, optimized EMS and MNNG mutant pots for each strain were plated on BHI agar containing 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal). Colonies that exhibited a blue color were selected for quantitative beta-gal activities using the o-nitrophenyl-beta-galactoside (ONPG) assay. Seventy-five mutants were obtained out of more than 2 million colonies screened and showed increased beta-galactosidase activities compared with the wild-type strains. EMS gave a higher frequency of beta-gal overproducing mutants than MNNG for three of the four strains, S. thermophilus, B. breve, and B. longum, whereas the frequency of L. delbrueckii ssp. bulgaricus beta-gal mutants was similar with both mutagens. The highest beta-gal increases, when induced during growth in lactose, for mutants of each culture were 137% for L. delbrueckii ssp. bulgaricus; 104% for S. thermophilus; 70% for B. breve; and 222% for B. longum mutants. This food-grade classical approach has the ability to moderately increase beta-gal concentrations in probiotic cultures to improve their potential for treating the symptoms of lactose malabsorption in humans.

Use of a single, triplicate arbitrarily primed-PCR procedure for molecular fingerprinting of lactic acid bacteria

Arbitrarily primed (AP)-PCR can be used to generate characteristic DNA fingerprint patterns. However, small changes in reaction conditions can cause band irreproducibility. In this study, a single methodology encompassing triplicate reactions, which were intentionally exposed to three different annealing temperatures, enabled bands that were reproducibly generated to be recognized. A single triplicate AP-PCR (TAP-PCR) procedure, using an 18-mer primer, was developed and used to fingerprint representative isolates from the major genera of lactic acid bacteria and Bifidobacterium to the strain level.

Cloning, sequencing, and expression of the pyruvate carboxylase gene in Lactococcus lactis subsp. lactis C2

A functional pyc gene was isolated from Lactococcus lactis subsp. lactis C2 and was found to complement a Pyc defect in L. lactis KB4. The deduced lactococcal Pyc protein was highly homologous to Pyc sequences of other bacteria. The pyc gene was also detected in Lactococcus lactis subsp. cremoris and L. lactis subsp. lactis bv. diacetylactis strains.

The sydney multicentre study of Parkinson's disease: progression and mortality at 10 years

OBJECTIVES

To report on a 10 year follow up of patients with idiopathic Parkinson's disease, particularly with respect to mortality and the effect of early treatment with bromocriptine.

METHODS

The patients are from the 149 new patients recruited for a double blind, randomised study of low dose levodopa-carbidopa versus low dose bromocriptine. Patients were examined neurologically at least yearly. Neuropsychological examinations were performed at 0, 3, 5, and 10 years. Mortality and cause of death in these patients were compared with the Australian population using standardised mortality ratios (SMRs). Mortality and disease progression were compared by sex and treatment group. Predictors of death within 10 years, nursing home admission, and progression in Columbia score of >/=20 points were examined by logistic regression analysis.

RESULTS

Thirteen patients were excluded as having atypical Parkinsonism and six were lost to follow up. All available patients have been followed up for 10 years. Fifty patients (38%) were dead by 10 years and 63 by the last follow up. The SMR was 1.58 for all patients (p<0. 001). There was no significant difference in SMRs between the sexes. The mean duration of disease until death was 9.1 years. Parkinson's disease was thought to have contributed substantially to the death of 30 patients. The most common cause of death was pneumonia. Women progressed at a similar rate to men until 8 years, when the severity of their disease as measured by Hoehn and Yahr stage became greater (p<0.05). Older age of onset correlated with increased risk of death but the SMR was increased even in those aged <70 years (SMR 1.80, p=0.03). Early use of bromocriptine did not reduce mortality or slow progression of disease. One quarter of all patients had been admitted to nursing homes by 10 years. Only four patients were still employed.

CONCLUSIONS

Mortality in Parkinson's disease remains increased despite low dose levodopa-carbidopa therapy and no additional benefit was gained from early use of bromocriptine. Duration of disease was similar to that in the era before levodopa.

Nisin independent induction of the nisA promoter in Lactococcus lactis during growth in lactose or galactose

Nisin biosynthesis is autoregulated extracellularly by the mature and modified peptide. To investigate other regulatory effects on nisin biosynthesis, a transcription fusion of the nisA promoter from Lactococcus lactis ATCC 11454 to the promoterless lacZ gene from Streptococcus thermophilus was constructed. This fusion construct, pDOC99, expressed beta-galactosidase in L. lactis ATCC 11454 growing in M17 medium containing glucose (M17G). Consistent with the known model for transcription of nisA, pDOC99 did not express beta-galactosidase in the non-nisin producer, L. lactis LM0230 grown in M17G, unless the nisRK genes (cloned in pDOC23) were included in trans and nisin was added to the medium. Growth of this strain in M17 containing lactose or galactose, resulted in nisA transcription, even in the absence of exogenous nisin. This expression was independent of pDOC23. Furthermore, nisA transcription in L. lactis LM0230(pDOC99) grown in M17G could be induced by the addition of exogenous galactose, with maximum induction occurring at concentrations > 5 mM.

Molecular characterization of the Lactococcus lactis LlaKR2I restriction-modification system and effect of an IS982 element positioned between the restriction and modification genes

The nucleotide sequence of the plasmid-encoded LlaKR2I restriction-modification (R-M) system of Lactococcus lactis subsp. lactis biovar diacetylactis KR2 was determined. This R-M system comprises divergently transcribed endonuclease (llaKR2IR) and methyltransferase (llaKR2IM) genes; located in the intergenic region is a copy of the insertion element IS982, whose putative transposase gene is codirectionally transcribed with llaKR2IM. The deduced sequence of the LlaKR2I endonuclease shared homology with the type II endonuclease Sau3AI and with the MutH mismatch repair protein, both of which recognize and cleave the sequence 5' GATC 3'. In addition, M. LlaKR2I displayed homology with the 5-methylcytosine methyltransferase family of proteins, exhibiting greatest identity with M. Sau3AI. Both of these proteins shared notable homology throughout their putative target recognition domains. Furthermore, subclones of the native parental lactococcal plasmid pKR223, which encode M. LlaKR2I, all remained undigested after treatment with Sau3AI despite the presence of multiple 5' GATC 3' sites. The combination of these data suggested that the specificity of the LlaKR2I R-M system was likely to be 5' GATC 3', with the cytosine residue being modified to 5-methylcytosine. The IS982 element located within the LlaKR2I R-M system contained at its extremities two 16-bp perfect inverted repeats flanked by two 7-bp direct repeats. A perfect extended promoter consensus, which represented the likely original promoter of the llaKR2IR gene, was shown to overlap the direct repeat sequence on the other side of IS982. Specific deletion of IS982 and one of these direct repeats via a PCR strategy indicated that the LlaKR2I R-M determinants do not rely on elements within IS982 for expression and that the efficiency of bacteriophage restriction was not impaired.

Procedure for quantifiable assessment of nutritional parameters influencing nisin production by Lactococcus lactis subsp. lactis

A modified rapid plate assay procedure was developed, that allowed quantifiable measurement of nisin production by Lactococcus lactis growing directly on agar media. Using this direct plate assay, several nutritional parameters were assessed for their influence on nisin production (as distinct from their influence on growth) by L. lactis subsp. lactis ATCC 11454 growing on standard M17 based media over 3 and 6 h incubation periods. Glucose was found to be the optimal carbon source tested, with glycerol having the greatest suppressive effect. The addition of salts suppressed nisin production on a per cell basis, except MnCl2. This direct plate method proved to be a good pilot assay for rapidly and quantifiably investigating the initial effects of different parameters on nisin production by L. lactis, prior to conducting more intensive broth batch culture assays. The data obtained in this study indicate that certain nutritional parameters can impose a repressive effect on nisin production. Elucidation of how these parameters control the amount of nisin produced will provide further insight into the regulation of nisin biosynthesis in L. lactis.

A leucine repeat motif in AbiA is required for resistance of Lactococcus lactis to phages representing three species

The abiA gene encodes an abortive bacteriophage infection mechanism that can protect Lactococcus species from infection by a variety of bacteriophages including three unrelated phage species. Five heptad leucine repeats suggestive of a leucine zipper motif were identified between residues 232 and 266 in the predicted amino acid sequence of the AbiA protein. The biological role of residues in the repeats was investigated by incorporating amino acid substitutions via site-directed mutagenesis. Each mutant was tested for phage resistance against three phages, phi 31, sk1, and c2, belonging to species P335, 936, and c2, respectively. The five residues that comprise the heptad repeats were designated L234, L242, A249, L256, and L263. Three single conservative mutations of leucine to valine in positions L235, L242, and L263 and a double mutation of two leucines (L235 and L242) to valines did not affect AbiA activity on any phages tested. Non-conservative single substitutions of charged amino acids for three of the leucines (L235, L242, and L256) virtually eliminated AbiA activity on all phages tested. Substitution of the alanine residue in the third repeat (A249) with a charged residue did not affect AbiA activity. Replacement of L242 with an alanine elimination phage resistance against phi 31, but partial resistance to sk1 and c2 remained. Two single proline substitutions for leucines L242 and L263 virtually eliminated AbiA activity against all phages, indicating that the predicted alpha-helical structure of this region is important. Mutations in an adjacent region of basic amino acids had various effects on phage resistance, suggesting that these basic residues are also important for AbiA activity. This directed mutagenesis analysis of AbiA indicated that the leucine repeat structure is essential for conferring phage resistance against three species of lactococcal bacteriophages.

Control of expression of LlaI restriction in Lactococcus lactis

The plasmid encoded LlaI R/M system from Lactococcus lactis ssp. lactis consists of a bidomain methylase, with close evolutionary ties to type IIS methylases, and a trisubunit restriction complex. Both the methylase and restriction subunits are encoded on a polycistronic 6.9 kb operon. In this study, the 5' end of the llal 6.9 kb transcript was determined by primer extension analysis to be 254 bp upstream from the first R/M gene on the operon, llalM. Deletion of this promoter region abolished LlaI restriction in L. lactis. Analysis of the intervening sequence revealed a 72-amino-acid open reading frame, designated llalC, with a conserved ribosome binding site and helix-turn-helix domain. Overexpression of llalC in Escherichia coli with a T7 expression vector produced the predicted protein of 8.2 kDa. Mutation and in trans complementation analyses indicated that C-LlaI positively enhanced LlaI restriction activity in vivo. Northern analysis and transcriptional fusions of the llal promoter to a lacZ reporter gene indicated that C x LlaI did not enhance transcription of the llal operon. Databank searches with the deduced protein sequence for llalC revealed significant homologies to the E. coli Rop regulatory and mRNA stabilizer protein. Investigation of the effect of C x LlaI on enhancement of LlaI restriction in L. lactis revealed that growth at elevated temperatures (40 degrees C) completely abolished any enhancement of restriction activity. These data provide molecular evidence for a mechanism on how the expression of a restriction system in a prokaryote can be drastically reduced during elevated growth temperatures, by a small regulatory protein.

A triggered-suicide system designed as a defense against bacteriophages

A novel bacteriophage protection system for Lactococcus lactis based on a genetic trap, in which a strictly phage-inducible promoter isolated from the lytic phage phi31 is used to activate a bacterial suicide system after infection, was developed. The lethal gene of the suicide system consists of the three-gene restriction cassette LlaIR+, which is lethal across a wide range of gram-positive bacteria. The phage-inducible trigger promoter (phi31P) and the LlaIR+ restriction cassette were cloned in Escherichia coli on a high-copy-number replicon to generate pTRK414H. Restriction activity was not apparent in E. coli or L. lactis prior to phage infection. In phage challenges of L. lactis(pTRK414H) with phi31, the efficiency of plaquing was lowered to 10(-4) and accompanied by a fourfold reduction in burst size. Center-of-infection assays revealed that only 15% of infected cells released progeny phage. In addition to phage phi31, the phi31P/LlaIR+ suicide cassette also inhibited four phi31-derived recombinant phages at levels at least 10-fold greater than that of phi31. The phi31P/LlaIR+-based suicide system is a genetically engineered form of abortive infection that traps and eliminates phages potentially evolving in fermentation environments by destroying the phage genome and killing the propagation host. This type of phage-triggered suicide system could be designed for any bacterium-phage combination, given a universal lethal gene and an inducible promoter which is triggered by the infecting bacteriophage.

Evaluation of using a short region of the recA gene for rapid and sensitive speciation of dominant bifidobacteria in the human large intestine

The feasibility of intragenerically characterizing bifidobacteria by a comparison of a short region within the recA gene was tested. An approximately 300 bp fragment of the recA gene was PCR-amplified from six species from the genus Bifidobacterium using primers directed to two universally conserved regions of the recA gene. A phylogenetic analysis of the sequenced recA products compared favorably to classification based on the 16S rRNA sequences of the species tested. To apply this rapid methodology to unknown human intestinal bifidobacteria, 46 isolates were randomly chosen from the feces of four subjects and initially characterized by RFLP analysis of a PCR-amplified region of their 16S RNA genes. From a representative of the dominant RFLP family in each of the subjects, the recA segment was PCR-amplified, sequenced and phylogenetically analyzed. All four isolates were found to be related to one another and to B. longum and B. infantis. These results illustrate that the recA gene may be useful for intrageneric phylogenetic analysis as well as for the identification of unknown fecal bifidobacteria.

Unusual manifestations of type 1 autoimmune polyendocrinopathy

We present a family with five members affected by Type 1 autoimmune polyendocrinopathy. All patients had chronic mucocutaneous candidiasis and dental abnormalities. Four patients had ocular abnormalities, four had hypoparathyroidism, and three had Addison's disease. The family was unusual in that all four affected females had premature ovarian failure. The ocular abnormalities included two patients with subcapsular lens opacities, one patient with asymptomatic corneal opacities, and one patient with severe bilateral iridocyclitis with cataract formation. One patient had pernicious anaemia and one had insulin dependent diabetes mellitus. All patients were negative on repeated occasions for organ specific and non-organ specific autoantibodies. Lymphocyte studies were performed in four patients. A deficiency of T suppressor cells was found in three and low normal levels were present in the fourth suggesting that the syndrome may be due to a defect in suppressor T cells.

Differentiation of ingested and endogenous bifidobacteria by DNA fingerprinting demonstrates the survival of an unmodified strain in the gastrointestinal tract of humans

Consumption of bifidobacteria as a dietary adjunct has received considerable attention for its possible role in the maintenance of gastrointestinal health. However, speculation exists about these presumed health benefits because of an inability to assess the fate and mechanism of action of ingested bifidobacteria. Thus, our objective was to examine the fate of ingested bifidobacteria through the gastrointestinal tract. Variations in the highly conserved 16S ribosomal DNA (rDNA) of bifidobacteria from six male subjects (18 to 35 y old) were assessed by restriction fragment length polymorphism (RFLP) analysis. During the 16-d study, 10(10) colony-forming units (CFU) of a commercially available bifidobacteria were delivered to subjects in fluid milk for each of 8 d. During the remaining 8 d, subjects consumed milk without bifidobacteria. Feces were collected at 4-d intervals and plated on selective media. For each subject, 10-15 colonies were randomly selected and used as template for PCR-amplification of 16S rDNA. 16S rDNA was restriction digested and resolved by electrophoresis. The 16S rDNA-RFLP of the ingested bifidobacteria was unique compared with bifidobacteria found in subjects prior to the feeding study. When subjects consumed bifidobacteria, a 16S rDNA-RFLP identical to that of the ingested bifidobacteria was observed in feces. The concentration of the ingested bifidobacteria in feces increased to 67.2 +/- 8.5% (mean +/- SEM) of total bifidobacteria. After feeding stopped, the ingested bifidobacteria diminished and became undetectable. Using this molecular approach to monitor ingested bifidobacteria, we demonstrate the kinetics of passage of this organism through the gastrointestinal tract of healthy humans.

Medial arterial calcification, calcific aortic stenosis and mitral annular calcification in a diabetic patient with severe autonomic neuropathy

Medial arterial calcification (Mönckeberg's arteriosclerosis) is well described in diabetic patients with autonomic neuropathy. There is also a high prevalence of diabetes mellitus among subjects with calcific aortic stenosis and mitral annular calcification. We describe a diabetic patient with autonomic neuropathy and extensive medial arterial calcification who also had calcification of the aortic valve and of the mitral valve annulus. We propose that autonomic neuropathy may play a role in calcification of these structures at the base of the heart.

Development of an expression strategy using a lytic phage to trigger explosive plasmid amplification and gene expression

A novel plasmid-based expression strategy, exploiting two features of lytic bacteriophages, was developed in Lactococcus lactis. Components of this system include a phage origin of replication and phage expression signals, which were induced to high efficiency upon phage infection of the host. Phage-specific expression signals were cloned from phi 31 in a promoter-screening strategy using the lacZ gene from Streptococcus thermophilus. One clone exhibited a significant induction in beta-galactosidase production and concomitant increase in lacZ mRNA during the phi 31 infection cycle of the host. Molecular characterization of the cloned insert revealed 888 bp positioned near the phi 31 cos site. Primer extension analysis showed that transcription was induced approximately 20 min following phi 31 infection at four points, apparently organized in two sets of tandem promoters on the cloned phage insert. One of these middle phage promoters also showed a basal level of activity prior to phage infection. The phi 31 promoter lacZ cassette was cloned into a low-copy-number vector plasmid containing the phi 31 origin of replication (ori31) and the resulting low-copy-number plasmid exhibited negligible beta-galactosidase production in L. lactis. However, > 2,000 units were detected following a deliberate infection with phi 31. A control expression plasmid without ori31 could only be induced to 85 units. The combination of these phage-inducible expression signals together with ori31 functioned synergistically to drive rapid and high efficiency expression of a heterologous gene in L. lactis.

Age at onset: the major determinant of outcome in Parkinson's disease

Factors at presentation which influenced the course of the disease and response to treatment were assessed in 125 de novo patients with Parkinson's disease. Ninety-eight patients were available for re-assessment at 5 years. Older patients presented earlier after the onset of symptoms, deteriorated more rapidly, and were significantly more likely to develop dementia and impairment of balance. Increasing age and symmetrical disease predicted the new appearance of imbalance. Age of onset did not predict dyskinesia or end of dose failure. A low tremor score at baseline and female gender were predictive of the early appearance of dyskinesia. Patients who experienced end of dose failure were taking a significantly higher dose of levodopa. Once dose and duration of treatment were corrected for, no baseline features were predictive of end of dose failure. The dose of levodopa at 5 years was positively correlated to baseline disease severity as measured by the Columbia score. We conclude that the age of onset of symptoms of Parkinson's disease is a major determinant of the course of the disease and response to treatment.

In vivo restriction by LlaI is encoded by three genes, arranged in an operon with llaIM, on the conjugative Lactococcus plasmid pTR2030

The LlaI restriction and modification (R/M) system is encoded on pTR2030, a 46.2-kb conjugative plasmid from Lactococcus lactis. The llaI methylase gene, sequenced previously, encodes a functional type IIS methylase and is located approximately 5 kb upstream from the abiA gene, encoding abortive phage resistance. In this study, the sequence of the region between llaIM and abiA was determined and revealed four consecutive open reading frames (ORFs). Northern (RNA) analysis showed that the four ORFs were part of a 7-kb operon with llaIM and the downstream abiA gene on a separate transcriptional unit. The deduced protein sequence of ORF2 revealed a P-loop consensus motif for ATP/GTP-binding sites and a three-part consensus motif for GTP-binding proteins. Data bank searches with the deduced protein sequences for all four ORFs revealed no homology except for ORF2 with MerB, in three regions that coincided with the GTP-binding motifs in both proteins. To phenotypically analyze the llaI operon, a 9.0-kb fragment was cloned into a high-copy-number lactococcal shuttle vector, pTRKH2. The resulting construct, pTRK370, exhibited a significantly higher level of in vivo restriction and modification in L. lactis NCK203 than the low-copy-number parental plasmid, pTR2030. A combination of deletion constructions and frameshift mutations indicated that the first three ORFs were involved in LlaI restriction, and they were therefore designated llaI.1, llaI.2, and llaI.3. Mutating llaI.1 completely abolished restriction, while disrupting llaI.2 or llaI.3 allowed an inefficient restriction of phage DNA to occur, manifested primarily by a variable plaque phenotype. ORF4 had no discernible effect on in vivo restriction. A frameshift mutation in llaIM proved lethal to L. lactis NCK203, implying that the restriction component was active without the modification subunit. These results suggested that the LlaI R/M system is unlike any other R/M system studied to date and has diverged from the type IIS class of restriction enzymes by acquiring some characteristics reminiscent of type I enzymes.

Iron-responsive gene expression in Pseudomonas fluorescens M114: cloning and characterization of a transcription-activating factor, PbrA

In response to iron limitation. Pseudomonas fluorescens M114 induces a number of genes including an iron-scavenging siderophore termed pseudobactin M114, its cognate receptor, PbuA, and a casein protease. A Tn5lacZ-induced mutant (M114FA1) was isolated that exhibits a pleiotropic phenotype and lacks the ability to express these iron-regulated genes. A cosmid clone was identified which complements this mutation. This clone is capable of activating a number of iron-regulated promoter fusion constructs from P. fluorescens M114 and Pseudomonas putida WCS358 and can also promote expression of these fusions in Escherichia coli. A series of insertion mutants was constructed by homologous recombination which were unable to transcribe the promoter fusions. DNA sequence analysis of the complementing region identified one open reading frame (ORF) termed pbrA (pseudobactin regulation activation) and the deduced amino acid sequence shows domains with significant homology to a number of ECF (extracytoplasmic function) transcriptional regulators of the sigma 70 sigma factor family, including fecl required for expression of the ferric dicitrate outer-membrane receptor protein of E. coli. Sequences upstream of the pbrA gene suggest that transcription of pbrA may also be iron regulated.

The Sydney Multicentre Study of Parkinson's disease: a randomised, prospective five year study comparing low dose bromocriptine with low dose levodopa-carbidopa

149 previously untreated patients with Parkinson's disease were recruited over a three year period and randomly allocated to either low dose levodopa-carbidopa (< or = 600/150 mg/day) or low dose bromocriptine (< or = 30 mg/day). A five year follow up is reported on the 126 patients who completed the dose titration and who have not developed features of atypical Parkinsonism. Levodopa-carbidopa in low dosage adequately controlled symptoms in most patients and delayed the appearance of dyskinesia and end of dose failure for about two years longer than conventional doses. Only a few patients could be managed for more than one year on low dose bromocriptine alone; these patients had mild disease and asymmetric signs. Patients randomised to bromocriptine did not develop dyskinesia or troublesome end of dose failure until levodopa-carbidopa was added. The prevalence of dyskinesia in this group was lower than in patients given levodopa-carbidopa alone. The prevalence of end of dose failure was similar in the two randomisation groups once levodopa was introduced.

Isolation of a gene (pbsC) required for siderophore biosynthesis in fluorescent Pseudomonas sp. strain M114

An iron-regulated gene, pbsC, required for siderophore production in fluorescent Pseudomonas sp. strain M114 has been identified. A kanamycin-resistance cassette was inserted at specific restriction sites within a 7 kb genomic fragment of M114 DNA and by marker exchange two siderophore-negative mutants, designated M1 and M2, were isolated. The nucleotide sequence of approximately 4 kb of the region flanking the insertion sites was determined and a large open reading frame (ORF) extending for 2409 bp was identified. This gene was designated pbsC (pseudobactin synthesis C) and its putative protein product termed PbsC. PbsC was found to be homologous to a family of enzymes involved in the biosynthesis of secondary metabolites, including EntF of Escherichia coli. These enzymes are believed to act via ATP-dependent binding of AMP to their substrate. Several areas of high sequence homology between these proteins and PbsC were observed, including a conserved AMP-binding domain. The expression of pbsC is iron-regulated as revealed when a DNA fragment containing the upstream region was cloned in a promoter probe vector and conjugated into the wild-type strain, M114. The nucleotide sequence upstream of the putative translational start site contains a region homologous to previously defined -16 to -25 sequences of iron-regulated genes but did not contain an iron-box consensus sequence. It was noted that inactivation of the pbsC gene also affected other iron-regulated phenotypes of Pseudomonas M114.

Escherichia coli ferric uptake regulator (Fur) can mediate regulation of a pseudomonad iron-regulated promoter

Introduction of a Pseudomonas iron-regulated promoter lacZ fusion (SP1) and a Pseudomonas transcriptional factor into Escherichia coli allowed expression of the promoter in this heterologous host. Evaluation of this promoter in wild-type and fur mutants of E. coli, by measuring beta-galactosidase activity, indicated that E. coli Fur can regulate the Pseudomonas promoter in response to iron starvation. Gel retardation assays suggested that purified Fur protein could interact with the SP1 promoter upstream of the transcriptional start. DNase I footprinting analysis established that Fur protected a primary 58-bp region (-50 to -106 bp). These protein/DNA interactions correlate with the observed in vivo regulation of the SP1 promoter in E. coli and indicate that Fur can functionally regulate a Pseudomonas iron-regulated promoter.

High- and low-copy-number Lactococcus shuttle cloning vectors with features for clone screening

High- and low-copy-number shuttle cloning vectors were constructed by incorporating the Escherichia coli P15A plasmid origin of replication into the pAM beta 1-derived vectors, pIL252 and pIL253. The resulting vectors were structurally stable in Lactococcus, which is a common feature of theta-replicating plasmids, and also displayed good structural stability in E. coli, possibly due to lack of a resolvase-encoding gene. All the vectors expressed erythromycin resistance (ErR) in both; brain heart infusion medium allowed clear selection of ErR in E. coli. Some of the vectors provided insertional inactivation of a cat (pTRKH1; pTRKL1) or tet (pTRKH1; pTRKH3; pTRKH5) gene to facilitate screening for clones. Multiple cloning sites in a lacZ gene, which expresses beta-galactosidase in lacZ alpha-complementing E. coli strains, were included in some vectors (pTRKH2/H5 and pTRKL2) to enable blue/white screening of clones on XGal plates. The 'H' and 'L' prefixes signify if the vector exists at high (H) or low (L) copy number in Lactococcus. Successful introduction of these vectors into Lactococcus, Enterococcus, Streptococcus and Lactobacillus highlights their utility for expanding the possibilities for genetic manipulation of these industrially significant bacteria.

Reliability of the Columbia scale for assessing signs of Parkinson's disease

Inter- and intrarater reliability in scoring the signs of Parkinson's disease using the original Columbia scale and a modified version of this, the Sydney scale, were assessed in five neurologists participating in a long-term study of Parkinson's disease. Scoring was done on video recordings of 41 patients whose disability ranged from mild to severe. Although all the neurologists were familiar with the scales and had received training designed to produce uniformity of scoring, interrater reliability was poor. The mean score for the Columbia scale varied from 18.6 to 30 and for the Sydney scale from 15.2 to 23.2. By contrast, intrarater reliability was good. This study highlights the limitations of clinical rating scales in Parkinson's disease when more than one rater is used. In designing clinical trials, every effort should be made to ensure that the same patient is always assessed by the same rater.

Traits of fluorescent Pseudomonas spp. involved in suppression of plant root pathogens

Certain members of the fluorescent pseudomonad group have been shown to be potential agents for the biocontrol of plant root diseases. The major problems with the commercialization of these beneficial strains are that few wild-type strains contain all the desired characteristics for this process and the performance of strains in different soil and climatic conditions is not reproducible. Consequently, prior to selection and/or improvement of suitable strains for biocontrol purposes, it is necessary to understand the important traits required for this purpose. The production of fluorescent siderophores (iron-binding compounds) and antibiotic compounds has been recognized as important for the inhibition of plant root pathogens. Efficient root colonization is also a prerequisite for successful biocontrol strains. This review discusses some of the characteristics of fluorescent pseudomonads that have been suggested to be important for biocontrol. The genetic organization and regulation of these processes is also examined. This information is necessary for attempts aimed at the improvement of strains based on deregulating pathways or introducing traits from one strain to another. The release of genetically engineered organisms into the environment is governed by regulations, and this aspect is summarized. The commercialization of fluorescent pseudomonads for the biological control of plant root diseases remains an exciting possibility. The understanding of the relevant characteristics will facilitate this process by enabling the direct selection and/or construction of strains which will perform under a variety of environmental conditions.

Serum ferritin in newly diagnosed and poorly controlled diabetes mellitus

Serum ferritin was measured in 50 patients at diagnosis of diabetes mellitus (DM) and in 20 patients with established DM and poor metabolic control. Twenty-two patients had hyperferritinemia at diagnosis. Four patients had a recognised cause for their hyperferritinemia. In the remaining 18 patients ferritin levels decreased from a mean of 506 +/- 3.6 (SE) ug/l at diagnosis to 254 +/- 29.2 ug/l seven months later (p < 0.001). Metabolic control improved significantly over the same time. All 20 patients with established DM and poor metabolic control had normal ferritin levels. When compared with the newly diagnosed hyperferritinemic patients no difference was found in levels of glycosylated haemoglobin, but ferritin values differed significantly between the two groups (p < 0.001). These results indicate that transient hyperferritinemia is a feature of newly diagnosed DM but not of established DM with poor control. If used to screen diabetic patients for haemochromatosis, serum ferritin should be measured in established DM rather than at diagnosis.

Induction of intramembranous particle clusters in mice with nephrogenic diabetes insipidus

In mice with hereditary nephrogenic diabetes insipidus (NDI), the inability of vasopressin to increase hydraulic water permeability is reflected in a lack of intramembranous particle (IMP) clusters in apical membranes of inner medullary collecting ducts. The lack arises from anomalously high activity of one or two isozymes of adenosine 3',5'-cyclic monophosphate-phosphodiesterase (cAMP-PDE). We asked whether inhibition of these isozymes with rolipram and cilostamide would raise not only the tissue content of cAMP but also and simultaneously restore IMP clusters. Inner medullary collecting ducts from NDI mice were incubated in vitro. Tissue content of cAMP (fmol of cAMP per bundle) and number of IMP clusters (per 100 microns 2 of principal cell apical membrane) were, respectively: control, 44.8 +/- 13.0 and 4.16 +/- 1.49; arginine vasopressin (AVP), 31.7 +/- 8.0 and 3.98 +/- 1.56; rolipram and cilostamide, 109.7 +/- 21.0 and 58.09 +/- 15.74; and AVP plus rolipram and cilostamide, 305.7 +/- 75 and 48.63 +/- 11.03 (with the last four values showing significant difference from control and AVP only, respectively). In addition, treating NDI mice with rolipram and cilostamide in vivo reduced their high fluid turnover. We conclude that failure by AVP to increase cAMP in cells of collecting ducts, which results from anomalously high activity of one or two specific isozymes of cAMP-PDE, is the major or sole cause for the excretion of hypotonic urine in NDI mice (DI +/+ Severe strain).

Long term efficacy of a pen injector

We assessed the long term efficacy of Novopen as a form of insulin administration. Records were obtained on 48 patients who were treated with Novopen between January '86 and October '88. Six patients were excluded due to insufficient data. The study group of 42 patients comprised 22 females and 20 males of average age 33 years (range 17-66). Mean Hb.A1 rose from 10.6% to 12.1% after Novopen therapy, a rise of 14.1%. This rise is both clinically and statistically significant (p less than 0.001; 99% confidence limits 0.59-2.78). Increases in weight and insulin dose were also noted, but did not reach statistical significance. The majority of patients felt Novopen was superior to twice daily insulin in terms of ease of administration (81%) and flexibility of lifestyle (95%), and all who were using Novopen wished to continue with it. More than 50% of patients admitted to altering their dietary habits while using Novopen. Despite continuing patient satisfaction with this form of insulin administration, its long-term use may be associated with sub-optimal metabolic control.

Regulation of iron assimilation: nucleotide sequence analysis of an iron-regulated promoter from a fluorescent pseudomonad

An iron-regulated promoter was cloned on a 2.1 kb Bg/II fragment from Pseudomonas sp. strain M114 and fused to the lacZ reporter gene. Iron-regulated lacZ expression from the resulting construct (pSP1) in strain M114 was mediated via the Fur-like repressor which also regulates siderophore production in this strain. A 390 bp StuI-PstI internal fragment contained the necessary information for iron-regulated promoter expression. This fragment was sequenced and the initiation point for transcription was determined by primer extension analysis. The region directly upstream of the transcription start point contained no significant homology to known promoter consensus sequences. However the -16 to -25 bp region contained homology to four other iron-regulated pseudomonad promoters. Deletion of bases downstream from the transcriptional start did not affect the iron-regulated expression of the promoter. The -37 and -43 bp regions exhibited some homology to the 19 bp Escherichia coli Fur-binding consensus sequence. When expressed in E. coli (via a cloned transacting factor from strain M114) lacZ expression from pSP1 was found to be regulated by iron. A region of greater than 77 bases but less than 131 upstream from the transcriptional start was found to be necessary for promoter activity, further suggesting that a transcriptional activator may be required for expression.