A feasibility study testing four hypotheses with phase II outcomes in advanced colorectal cancer (MRC FOCUS3): a model for randomised controlled trials in the era of personalised medicine?

BACKGROUND

Molecular characteristics of cancer vary between individuals. In future, most trials will require assessment of biomarkers to allocate patients into enriched populations in which targeted therapies are more likely to be effective. The MRC FOCUS3 trial is a feasibility study to assess key elements in the planning of such studies.

PATIENTS AND METHODS

Patients with advanced colorectal cancer were registered from 24 centres between February 2010 and April 2011. With their consent, patients' tumour samples were analysed for KRAS/BRAF oncogene mutation status and topoisomerase 1 (topo-1) immunohistochemistry. Patients were then classified into one of four molecular strata; within each strata patients were randomised to one of two hypothesis-driven experimental therapies or a common control arm (FOLFIRI chemotherapy). A 4-stage suite of patient information sheets (PISs) was developed to avoid patient overload.

RESULTS

A total of 332 patients were registered, 244 randomised. Among randomised patients, biomarker results were provided within 10 working days (w.d.) in 71%, 15 w.d. in 91% and 20 w.d. in 99%. DNA mutation analysis was 100% concordant between two laboratories. Over 90% of participants reported excellent understanding of all aspects of the trial. In this randomised phase II setting, omission of irinotecan in the low topo-1 group was associated with increased response rate and addition of cetuximab in the KRAS, BRAF wild-type cohort was associated with longer progression-free survival.

CONCLUSIONS

Patient samples can be collected and analysed within workable time frames and with reproducible mutation results. Complex multi-arm designs are acceptable to patients with good PIS. Randomisation within each cohort provides outcome data that can inform clinical practice.

A review of K-wire related complications in the emergency management of paediatric upper extremity trauma

INTRODUCTION

Kirschner wires (K-wires) are immensely versatile in fracture fixation in the paediatric population. Complications associated with the K-wiring procedure vary from minor to a life-threatening. The aim of this study was to analyse the outcome of fracture fixation using K-wires in all types of upper-extremity fractures in children in order to assess the incidence and type of complication critically.

PATIENTS AND METHODS

Between September 1999 and September 2001, we retrospectively reviewed a consecutive series of 105 fractures in 103 paediatric trauma cases (below 12 years) treated with K-wires in a university teaching hospital. The case notes and radiographs were reviewed by an independent single assessor. All paediatric, acute, upper-extremity, displaced and unstable fractures were included. All elective procedures using K-wires were excluded.

RESULTS

We observed an overall 32.3% complication rate associated with the K-wiring procedure affecting 34 pins (24 patients). Wound-related complications included over-granulation in 13 cases, pin tract infection in 6 cases and hypersensitive scar in 1 case. Neurapraxia was found in 3 patients and axonotmesis in 1 patient. Wire loosening at the time of removal in 14 cases and retrograde wire migration in 4 cases were observed. There were 2 cases of penetrating tendonitis and 1 case of osteomyelitis. There was a higher complication rate in terms of wire loosening and pin tract infection when the K-wires: (i) were left outside the skin compared with those placed under the skin; (ii) stayed longer in the patients; and (iii) did not traverse both cortices. There were more complications in complex operations performed by senior surgeons (P = 0.056). The duration of K-wire stay, associated co-morbidity and anatomical location were statistically insignificant.

CONCLUSIONS

Complications are part of operative procedures; an important point to consider is what causes them in order to take preventative measures. We recommend that the risks and complications should be explained to parents during the consenting process to allay their anxiety, irrespective of the fact that most complications are minor and of short duration.

Flexible intramedullary nailing of displaced diaphyseal forearm fractures in children

INTRODUCTION

This study analyses the results of 50 displaced diaphyseal forearm fractures in children treated with flexible intramedullary nailing.

METHODS

Between 1999 and 2002 we treated 50 children aged between 5 and 15 years, with diaphyseal fractures of the forearm using Flexible intramedullary nailing (FIN). Both bones were fractures in 45 patients, radius only in 4 and ulna only in 1. The indications for fixation were instability (26), re-displacement (20), and open fractures (4).

RESULTS

24 patients were reduced closed, followed by nailing, while 26 fractures required open reduction of either one bone(16 cases) or both bones(10 cases) prior to nailing. Bony union of all fractures was achieved by an average of 7 weeks (range 6 weeks to 4 months) with one delayed union. Pronation was restricted by an average of 20 degrees in 9 patients. Two patients developed post operative compartment syndrome requiring fasciotomy. Three patients were lost to follow-up.

INTERPRETATION

FIN led to early bony union with acceptable bony alignment in all 47 patients available at final follow-up. We therefore recommend FIN for the treatment of unstable diaphyseal forearm fractures in children.

Complex pediatric elbow injury: an uncommon case

Background

There is paucity of literature describing complex elbow trauma in the pediatric population. We described a case of an uncommon pediatric elbow injury comprised of lateral condyle fracture associated with posterolateral dislocation of elbow.

Case presentation

A 12-year-old boy sustained a direct elbow trauma and presented with Milch type II lateral condyle fracture associated with posterolateral dislocation of elbow. Elbow dislocation was managed by closed reduction. The elbow stability was assessed under general anaesthesia, followed by open K-wiring for the lateral condylar fracture fixation. The patient had an uneventful recovery with an excellent outcome at 39 months follow-up.

Conclusion

Complex pediatric elbow injuries are quite unusual to encounter, the management of such fractures can be technically demanding. Concomitant elbow dislocation should be managed by closed reduction followed by open reduction and internal fixation (K-wires or cannulated screws) of the lateral condyle fracture.

Genomic deletions in MSH2 or MLH1 are a frequent cause of hereditary non-polyposis colorectal cancer: identification of novel and recurrent deletions by MLPA

Gene dosage abnormalities account for a significant proportion of the mutations in genes tested in DNA diagnostic laboratories. Detection of these changes has proved a challenge as the methods available to date are time consuming or unreliable. The multiplex ligation-dependent probe assay (MLPA) is a new technique allowing relative quantification of up to 40 different nucleic acid sequences in a single reaction tube. We have evaluated MLPA for potential use in the diagnostic setting against the following criteria: accuracy, reagent cost, hands-on time, reliability, and retests required. A total of 215 UK patients referred for genetic testing on the basis of a family history consistent with autosomal dominant hereditary non-polyposis colorectal cancer (HNPCC or Lynch syndrome) were tested by MLPA. Of these, 12 cases with deletions of one or more exons were identified, six with MLH1 deletions and six with MSH2 deletions. Test failure rates were less than 5% and overall mutation detection sensitivity in this series was increased by approximately 50% by the inclusion of MLPA for an additional testing cost of about 10%. Two novel mutations in MSH2 and 10 novel point mutations in MLH1 were also identified during the course of this study. We conclude that MLPA is a cost effective and robust gene dosage method that can be readily adopted by diagnostic services. Comprehensive mutation scanning for MSH2 and MLH1 is incomplete without gene dosage analysis.

Isolation of a rhabdovirus during outbreaks of disease in cyprinid fish species at fishery sites in England

A virus was isolated during disease outbreaks in bream Abramis brama, tench Tinca tinca, roach Rutilis rutilis and crucian carp Carassius carassius populations at 6 fishery sites in England in 1999. Mortalities at the sites were primarily among recently introduced fish and the predominant fish species affected was bream. The bream stocked at 5 of the 6 English fishery sites were found to have originated from the River Bann, Northern Ireland. Most fish presented few consistent external signs of disease but some exhibited clinical signs similar to those of spring viraemia of carp (SVC), with extensive skin haemorrhages, ulceration on the flanks and internal signs including ascites and petechial haemorrhages. The most prominent histopathological changes were hepatocellular necrosis, interstitial nephritis and splenitis. The virus induced a cytopathic effect in tissue cultures (Epithelioma papulosum cyprini [EPC] cells) at 20 degrees C and produced moderate signals in an enzyme immunoassay (EIA) for the detection of SVC virus. The virus showed a close serological relationship to pike fry rhabdovirus in both EIA and serum neutralisation assays and to a rhabdovirus isolated during a disease outbreak in a bream population in the River Bann in 1998. A high degree of sequence similarity (> or = 99.5% nucleotide identity) was observed between the English isolates and those from the River Bann. Experimental infection of juvenile bream, tench and carp with EPC cell-grown rhabdovirus by bath and intraperitoneal injection resulted in a 40% mortality of bream in the injection group only. The virus was re-isolated from pooled kidney, liver and spleen tissue samples from moribund bream. The field observations together with the experimental results indicate that this rhabdovirus is of low virulence but may have the potential to cause significant mortality in fishes under stress.

Nucleotide sequence analysis of the glycoprotein gene of putative spring viraemia of carp virus and pike fry rhabdovirus isolates reveals four genogroups

RT-PCR methods have been applied to the detection and sequencing of the glycoprotein gene of putative spring viraemia of carp viruses (SVCV) and pike fry rhabdoviruses (PFRV), including isolates from tench, grass carp, roach, bream and false harlequin, sheatfish and orfe. Phylogenetic analysis of a 550 nucleotide (nt) region of the glycoprotein gene identified 4 groups, I to IV. Significantly, the majority of viruses previously identified as PFRV formed a distinct cluster (Genogroup IV) which shared <80% nucleotide identity with the PFRV reference strain (Genogroup III). The similarity between another PFRV-like virus isolated from grass carp and representatives of Genogroups III and IV was also <80%, indicating that this virus belonged to a third group (Genogroup II). All of the putative SVC viruses were assigned to a 4th group (Genogroup I), sharing <61% nucleotide identity with viruses in Genogroups II to IV.

The detection of large deletions or duplications in genomic DNA

While methods for the detection of point mutations and small insertions or deletions in genomic DNA are well established, the detection of larger (>100 bp) genomic duplications or deletions can be more difficult. Most mutation scanning methods use PCR as a first step, but the subsequent analyses are usually qualitative rather than quantitative. Gene dosage methods based on PCR need to be quantitative (i.e., they should report molar quantities of starting material) or semi-quantitative (i.e., they should report gene dosage relative to an internal standard). Without some sort of quantitation, heterozygous deletions and duplications may be overlooked and therefore be under-ascertained. Gene dosage methods provide the additional benefit of reporting allele drop-out in the PCR. This could impact on SNP surveys, where large-scale genotyping may miss null alleles. Here we review recent developments in techniques for the detection of this type of mutation and compare their relative strengths and weaknesses. We emphasize that comprehensive mutation analysis should include scanning for large insertions and deletions and duplications.

Growth-rate periodicity of Streptomyces levoris during space flight

Streptomyces levoris Kras was used is an experimental test micro-organism during the Apollo Soyuz Test Project to study alternating vegetative mycelial and spore ring periodicity during space flight. Four cultures were launched in each of the spacecrafts (Apollo and Soyuz). During the joint space-flight activities, two cultures from each spacecraft were exchanged. Selected duplicate cultures were maintained as controls in both the USA and the USSR. Spore ring morphology was periodically documented by photographing the specimens at approximately 12-hr intervals during the pre-, in-, and post-flight periods of the experiment. A decreased growth-rate periodicity in all but one of the eight space-flight cultures was in part attributed to the reduced temperature in the spacecraft. One of the eight cultures grew at a faster rate in the reduced temperature environment of Apollo than did the ground controls. Three of the space-flight cultures developed double spore rings during the immediate post-flight period. This anomaly was attributed to re-entry into the earth's gravity. The absence of spores in portions of one ring formed during space flight may have been caused by nutritional defects or media abnormality. Extensive studies will be required to elucidate the cause of this detect with certainty. There was no visible evidence of wedges in the cultures which would suggest naturally occurring or radiation-induced mutagenic alteration during space flight.

Medically important micro-organisms recovered from Apollo-Soyuz Test Project (ASTP) crew members

The possibility of significant alterations in the microbial populations inhabiting the integument and upper respiratory tract of space flight crew members has been proposed by various authors. The Apollo-Soyuz Test Project (ASTP), a unique space flight in which two teams of crew members from different geographical areas joined in space, presented an unusual opportunity to evaluate in-flight cross-contamination and other anomalous behavior of the microbial populations. Accordingly, the medically important microbes recovered from the five (3 USA and 2 USSR) ASTP crew members before and after flight were evaluated in relation to specific theoretical alterations. The phenomenon of "simplification", in which the number of different types of species is reduced during spaceflight, did not occur within the population of medically important micro-organisms. Spontaneous post-flight illness due to infectious agents ("Microbial Shock") was also absent. Intracrew transfer of pathogens was established, but intercrew transfer was absent. Dysbacteriosis, in which sampled areas are flooded with unusually large numbers of a single type of micro-organism, was not demonstrated although there was a significant increase in the incidence of gram-negative rods in the oral cavities of the two cosmonauts. The importance of all of these and other observations of the medically important micro-organisms recovered from ASTP crew members are explored with respect to past and future space flights.

Viability of Bacillus subtilis spores exposed to space environment in the M-191 experiment system aboard Apollo 16

During the Apollo 16 space flight, in the experiment system M-191, (microbial response to space environment) spores of Bacillus subtilis 168 were exposed to space vacuum or solar UV irradiation with a peak wavelength of 254 nm or both. The effects of these space factors on the colony-forming ability of the spores were studied. It was found (i) that space vacuum alone did not affect the survival of pre-dried spores; (ii) that space vacuum in combination with solar UV irradiation with a peak wavelength of 254 nm had a synergistic effect, which may by attributed to a UV supersensitivity of the spores during vacuum exposure. These results agreed with findings of simulation experiments on earth. It was concluded that air dried spores may survive exposure to space vacuum if shielded against solar UV irradiation.

Effects of solar ultraviolet radiations on Bacillus subtilis spores and T7 bacteriophage

Spores of Bacillus subtilis HA 101 and the DNA polymerase I-defective mutant HA 101 (59) F were exposed to selected wavelengths of solar ultraviolet light and space vacuum during the return of Apollo 16. In addition, coliphage T7 suspensions were exposed to solar ultraviolet radiation as part of the Microbial Response to Space Environment Experiment. Optical filters were employed to provide different energy levels at wavelengths 254 nm and 280 nm. Dose-response curves for lethal and mutagenic effects were compared with ground-based data. A close parallel was observed between the results of solar radiation and ground tests with spores of the two strains. However, significantly greater inactivation of T7 bacteriophage was observed after exposure to solar ultraviolet radiation.

Physical dosimetric evaluations in the Apollo 16 microbial response experiment

Nine biological species, including viruses, bacteria, fungi, and nematodes, were exposed to various combinations of space vacuum, galactic radiation, and solar UV light during the Apollo 16 space flight. No major changes in number of surviving cells occurred, permitting detailed genetic and somatic studies of returned test subjects. To enable dose-response studies, solar UV was employed as a mutagenic source with cells exposed to full sunlight or to components of the UV spectrum at peak wavelengths of 254, 280, and 300 nanometers over a range of energy levels. Proper in-flight UV irradiation monitoring required the development of a potassium ferrioxalate actinometer and an anaerobic photographic emulsion dosimeter which were tested for the first time in space. Studies of the mutagenic activity of cosmic-ray particulate radiation environment required measurement of its components with several lithium fluoride thermoluminescent dosimeters and a package of passive nuclear-track detectors capable of recording high-energy multicharge particles. These detectors included cellulose nitrate, Lexan, Ilford G5, and silver chloride crystals. The nuclear track detectors measured the incident heavy particles with the recorded spherical fluences with LET350,H2O>100 keV x micrometers-1 to be 19.3 +/- 1.8 particles cm-2. This value was found to be lower than that recorded by detectors located in the Biostack and the passive personnel dosimeters worn by the astronauts, suggesting a somewhat greater average shielding.

Investigations on a clinically and functionally unusual and novel germline p53 mutation

This report describes an individual with a rare choroid plexus papilloma in adulthood (age 29) after earlier having an osteosarcoma (age 22). The results from this study, and others, suggest that it may be advisable to consider the possibility of a germline p53 mutation in adults presenting with choroid plexus tumours. In the current study automated DNA sequencing of genomic DNA detected a novel germline 7 base pair insertion in exon 5 of the p53 gene in this patient. The alteration in frame would produce amino acid substitutions beginning with alanine to glycine at position 161 and a stop codon at position 182 in the mutated protein. Surprisingly two assays of p53 function gave apparently wild-type results on peripheral blood lymphocytes from this individual. These results led us to carry out more detailed functional tests on the mutant protein. The mutant allele was expressed either at very low levels or not at all in phytohaemagglutinin stimulated lymphocytes. Further, the mutant protein was completely non-functional in terms of its ability to transactivate a series of p53-responsive genes (p21(WAF1), bax, PIG3), to transrepress a target gene and to inhibit colony growth in transfected Saos-2 cells. However, surprisingly, data from irradiated peripheral blood lymphocytes and transfected Saos-2 cells, suggested that this truncated, mutant protein retains significant ability to induce apoptosis.

A common founder for the 35delG GJB2 gene mutation in connexin 26 hearing impairment

Fifty to eighty percent of autosomal recessive congenital severe to profound hearing impairment result from mutations in a single gene, GJB2, that encodes the protein connexin 26. One mutation of this gene, the 35delG allele, is particularly common in white populations. We report evidence that the high frequency of this allelic variant is the result of a founder effect rather than a mutational hot spot in GJB2, which was the prevailing hypothesis. Patients homozygous for the 35delG mutation and normal hearing controls originating from Belgium, the UK, and the USA were genotyped for different single nucleotide polymorphisms (SNPs). Four SNPs mapped in the immediate vicinity of GJB2, while two were positioned up to 76 kb from it. Significant differences between the genotypes of patients and controls for the five SNPs closest to GJB2 were found, with nearly complete association of one SNP allele with the 35delG mutation. For the most remote SNP, we could not detect any association. We conclude that the 35delG mutation is derived from a common, albeit ancient founder.

A comparison of methods for gene dosage analysis in HMSN type 1

A number of different approaches are used in diagnostic laboratories to detect the 1.5 Mb duplication at 17p11.2 seen in approximately 70% of patients with hereditary motor and sensory neuropathy type 1 (HMSN1). Here we compare the methods used in UK diagnostic laboratories to detect the duplication. Samples referred to participating centres for HMSN testing were collected, randomised, and distributed for testing. One hundred samples were examined using five different methods; each method was tested by two independent laboratories. Identical results were obtained from all laboratories for 44 samples. The remaining samples were classified as duplication positive or duplication negative on the basis of the same result by two or more methods. A total of 95 samples were classified by more than one method, two were withdrawn from the study as the same result was not obtained by two methods, and three are thought to have a duplication smaller than 1.5 Mb. Seven of 49 duplications were not detected by methods used to detect the common junction fragment and the use of microsatellites failed to yield a result in four of 95 samples. Sequence tagged site (STS) dosage analysis was found to be the most sensitive of the methods tested, although this method was found to be the most likely to require repeat analysis. Eight samples gave discordant results between the two laboratories testing by the same method. Upon retesting, reasons for the initial incorrect result included processing and typographical errors.

Genetic analysis of the connexin-26 M34T variant: identification of genotype M34T/M34T segregating with mild-moderate non-syndromic sensorineural hearing loss

Mutations in the human gap junction beta-2 gene (GJB2) that encodes connexin-26 have been shown to cause non-syndromic sensorineural hearing loss (NSSNHL) at the DFNB1 locus on 13q11. Functional and genetic data regarding the disease causing potential of one particular GJB2 sequence variant, 101 T-->C (M34T), have proven contradictory. In this study, we found the prevalence of the M34T allele in a cohort of white sib pairs and sporadic cases with NSSNHL from the United Kingdom and Ireland to be 3.179% of chromosomes screened. Significantly, we identified the first M34T/M34T genotype cosegregating in a single family with mid to high frequency NSSNHL. Screening a control population of 630 subjects we identified 25 M34T heterozygotes; however, no M34T homozygotes were detected. Surprisingly, the majority of M34T alleles (88%) were in cis with a 10 bp deletion in the 5' non-coding sequence. This non-coding deletion was also homozygous in the homozygous M34T subjects. Microsatellite analysis of flanking loci in M34T heterozygotes and controls does not define an extensive ancestral haplotype but preliminary data suggest two common alleles in subjects with the M34T allele. In summary, we provide data that support M34T acting as a recessive GJB2 allele associated with mild-moderate prelingual hearing impairment.

A comparison of fluorescent SSCP and denaturing HPLC for high throughput mutation scanning

We examined 67 different mutations in 16 different amplicons in a comparison of mutation detection by fluorescent single strand conformation polymorphism (F-SSCP) and by denaturing HPLC (DHPLC). F-SSCP was used to analyze fluorescent amplicons with internal size standards and automated fragment analysis (GeneScan, PE Applied Biosystems, Foster City, CA). In DHPLC, unlabelled amplicons were analyzed by reverse phase HPLC with fragment detection by absorbance at 260nm. Both methods had high sensitivity (95-100%) and specificity (100%). Overall, F-SSCP with external temperature control was the more sensitive method, but DHPLC was particularly useful for the rapid analysis of novel fragments.

Exon deletions and duplications in BRCA1 detected by semiquantitative PCR

rearrangements have recently been identified in the BRCA1 gene. Inclusion of a method for identifying such rearrangements should now be a prerequisite for providing a comprehensive mutation detection strategy. We have developed a semiquantitative PCR-based fluorescent assay for the detection of previously identified deletions. This method avoids the need for long PCR or Southern blotting and is suitable for large-scale epidemiological studies. The assay was used to screen 44 high-risk families within the U.K. Yorkshire Health Region. No deletions were detected, but five cases (11%) with an apparent duplication of exon 13 in BRCA1 were identified. The presence of this mutation was confirmed by long PCR. Further developments include extending the assay to include all exons of BRCA1.

An investigation of the geological and geomorphological features of Fowlers Gap using thermal infrared, radar and airborne geophysical remote sensing techniques

This study summarises the application of several remote sensing techniques to investigate various components of a land surface in the semi-arid environment of Fowlers Gap. These remote sensing techniques included NASA's Thermal Infrared Multispectral Scanner (TIMS) and CSIRO's Mid-Infrared Airborne CO, Laser Spectrometer (MIRACO,LAS), NASA's AIRSAR radar and geophysical airborne radiometrics. Linear spectral unmixing of extracted emissivities from the TIMS data produced four endmembers: quartz, clay minerals, dry vegetation (cellulose) in fine soils, and green vegetation/moisture. MIRAC0,LAS data identified spectral signatures similar to the spectra of endmembers derived from TIMS data. The sensitivity of both thermal infrared remote sensing techniques to the quartzklay contents and textures of the soils and sediments was confirmed by detailed laboratory spectral measurements. Surface roughness information from AIRSAR's band C radar backscatter assisted the discrimination of alluvial and colluvial quartz and clay-rich deposits from the outcropping geological units. In particular the C band AIRSAR radar discriminated the coarse grained sandstone and quartzite scree within the colluvial pediments, from the finer grained quartz-rich 'radar smooth' alluvium in the scalds. Airborne radiometrics were also found useful for further discriminating potassium and thorium- bearing phyllosilicate/clay minerals, within shales and ghyllites, from the kaolinite and montmorillonite- rich alluvium. This study found that TIMS data could identify some of the geomorphological features at Fowlers Gap, such as colluvial pediments, depositional scalds and gilgai landforms, that characterise some of the land systems in the Lowlands and Plains relief class of the Fowlers Gap land system classification. Thermal infrared remote sensing techniques also proved capable of discriminating areas of cellulose-rich dry vegetation and fine grained soils within the Plains relief class. The sensitivity of AIRSAR radar for topographic relief and surface roughness suggests that it is useful for distinguishing land systems in the Ranges relief class. Radiometrics appeared useful for land system definition when outcropping argillaceous units and alluvium assisted their classification. Key words: remote sensing, Fowlers Gap, thermal infrared, land system, spectral unmixing

Congenital non-syndromal sensorineural hearing impairment due to connexin 26 gene mutations--molecular and audiological findings

We screened DNA from 72 sibships and 138 sporadically affected individuals with congenital non-syndromal sensorineural hearing impairment (NSSNHI) for mutations in the 26 (CX26) gene. A total of 20 (27.8%) of the sibships and 11 (7.9%) of the sporadically affected individuals were homozygous or compound heterozygotes for CX26 mutations. A total of 11 (17.2%) of 64 individuals with severe and 30 (30%) of 100 with profound NSSNHI compared to eight (8.7%) of 92 persons with moderate and none (0%) of 19 individuals with mild hearing impairment were homozygous or compound heterozygotes for CX26 mutations (chi2 test, 3 df, P = 0.000). CX26 mutation status bad no effect on the symmetry of the hearing impairment or configuration of the audiogram. In addition, serial audiograms showed no evidence of progression of the hearing impairment or differences in the severity of the hearing impairment in affected siblings in persons whether or not due to CX26 mutations. Sporadically affected individuals with congenital NSSNHI should be routinely tested for mutations in CX26, especially if the hearing impairment is severe or profound in severity, since identification of a mutation in CX26 allows use of Mendelian recurrence risks.

Comparison of enzyme mismatch cleavage and chemical cleavage of mismatch on a defined set of heteroduplexes

Two mutation detection methods based on the cleavage of mismatched heteroduplexes were compared and evaluated. These techniques, chemical cleavage of mismatch (CCM) and enzyme mismatch cleavage (EMC), have the advantages over other available methods of being able to detect and localize mutations in relatively large fragments of DNA (> or = 1 kb). We have constructed clones that enable us to create heteroduplexes of 500 bp, 1 kb, and 1.5 kb and have assessed each of the methods over a range of criteria. Both were able to detect and localize all four types of single-base mismatch and insertion/deletions of 1-5 bp. Whereas EMC was efficient at detection of insertion/deletions in a broad size range of fragments and has the advantage over CCM of using no hazardous chemicals, in our hands it has not been sufficiently robust that we felt confident to consider it for diagnostic use in its present form. CCM using hydroxylamine was efficient over the entire range of fragment sizes tested and using potassium permanganate with tetraethylammonium chloride was efficient up to 1 kb.

The effect of the daily intake of inulin on fasting lipid, insulin and glucose concentrations in middle-aged men and women

The present study was carried out to examine the effect of the daily intake of 10 g inulin on fasting blood lipid, glucose and insulin levels in healthy middle-aged men and women with moderately raised total plasma cholesterol (TC) and triacylglycerol (TAG) levels. This study was a double-blind randomized placebo-controlled parallel study in which fifty-four middle-aged subjects received either inulin or placebo for a period of 8 weeks. Fasting blood samples were collected before the supplementation period (baseline samples 1 and 2, separated by 1 week) and at weeks 4 and 8, with a follow-up at week 12. Compared with baseline values, insulin concentrations were significantly lower at 4 weeks (P < 0.01) in the inulin group. There was a trend for TAG values, compared with baseline, to be lower in the inulin group at 8 weeks (P < 0.08) returning to baseline concentrations at week 12. On comparison of the inulin and placebo groups, the fasting TAG responses over the 8-week test period were shown to be significantly different (P < 0.05, repeated measures ANOVA), which was largely due to lower plasma TAG levels in the inulin group at week 8. The percentage change in TAG levels in the inulin group during the 8-week study was shown to correlate with the initial TAG level of the subjects (rs -0.499, P = 0.004). We therefore conclude that the daily addition of 10 g inulin to the diet significantly reduced fasting insulin concentrations during the 8-week test period and resulted in lower plasma TAG levels, particularly in subjects in whom fasting TAG levels were greater than 1.5 mmol/l. These data support findings from animal studies that fructans influence the formation and/or degradation of TAG-rich lipoprotein particles, and the insulin data are also consistent with recent studies showing attenuation of insulin levels in fructan-treated rats.

Tepoxalin enhances the activity of an antioxidant, pyrrolidine dithiocarbamate, in attenuating tumor necrosis factor alpha-induced apoptosis in WEHI 164 cells

The nuclear transcription factor-kappaB (NF-kappaB) and free radicals are known to be involved in apoptosis. We studied the effects of a series of di-aryl-substituted pyrazole NF-kappaB inhibitors including tepoxalin on tumor necrosis factor alpha (TNFalpha)-induced apoptosis in murine fibrosarcoma WEHI 164 cells. We found that potent inhibitors of NF-kappaB were also effective in attenuating apoptosis. WEHI 164 cells that had been dually treated with tepoxalin and the antioxidant pyrrolidine dithiocarbamate (PDTC) were significantly protected from TNFalpha-induced killing. To study the role of free radicals in mediating TNFalpha-induced apoptosis, stable WEHI 164 cells overexpressing Bcl-2, an antioxidant protein, were generated. These cells were protected from TNFalpha-induced apoptosis and neither tepoxalin nor PDTC provided further significant protection. These results suggest that Bcl-2, PDTC, and tepoxalin may attenuate apoptosis in this system by affecting the same signaling pathway or converging pathways. Because tepoxalin suppresses the release of free radicals, PDTC scavenges free radicals and Bcl-2 is an antioxidant protein, free radicals are among the key mediators of this TNF-induced killing event. Tepoxalin and antioxidants may be useful in developing new therapeutics for treating neurodegenerative diseases, autoimmune deficiency syndrome, and ischemia-reperfusion injuries.

Enzymatic and chemical cleavage methods

Cleavage-based methods of mutation detection offer a simple and intuitive means to detect and in most cases locate mutations within DNA fragment sizes ranging from 500 to 1500 bases. Their main advantages as a presequencing screening technology when scanning for unknown mutations is the potential to increase throughput by multiplexing. Combined with lower reagent costs per sample, mutation scanning methods offer significant advantages over currently available sequencing techniques and are likely to be of increasing importance as genomic sequence data becomes more readily available. Although enzymatic methods offer the advantages of simpler and less hazardous protocols, at present the most robust cleavage methods are based around chemical methods.

Enzymatic methods for mutation scanning

Enzymatic methods for mutation scanning still lack the sensitivity and specificity of the chemical cleavage of mismatch method. However developments in our understanding of the mismatch recognition process should lead to improvements. Several promising candidates exist with potential for more specific and sensitive mutation detection.

Effects of probiotics and prebiotics on blood lipids

Since the early work of Mann and Spoerry, probiotics in the form of fermented milk products have been reputed to have cholesterol-lowering properties in humans. However, studies conducted since the early 1970s have produced equivocal findings, with interpretation of the outcomes complicated by use of excessive quantities of product, inadequate sample sizes, failure to control nutrient intake and energy expenditure and variations in baseline blood lipids. More recent studies are of better quality, but fail to provide convincing evidence that 'live' fermented milk products have cholesterol-lowering efficacy in man. Future studies using probiotics should ensure adequate sample sizes sufficient to detect relatively small changes in blood cholesterol and should be conducted over longer periods of time. The recent introduction of the concept of prebiotics has directed attention towards the possibility that alterations in gut microflora induced by the fermentation of non-digestible components of the diet may also have the potential to influence systemic lipid metabolism. This possibility has been strengthened by the observation that in animals, dietary oligofructosaccharides cause suppression of hepatic triglyceride and VLDL synthesis, resulting in marked reductions in triglyceride, and to a lesser extent cholesterol, levels. Evidence for similar effects in humans is sparse and more studies are needed, particularly with respect to effects on postprandial triglyceride concentrations.

Do transplanted corneal limbal stem cells survive in vivo long-term? Possible techniques to detect donor cell survival by polymerase chain reaction with the amelogenin gene and Y-specific probes

PURPOSE

To investigate donor cell survival following corneal limbal stem cell grafting, which is based on the corneal stem cell model.

METHODS

We describe the use of the amelogenin gene probe with the polymerase chain reaction (PCR) to detect surviving donor cells and report preliminary studies using Y-specific DNA probes.

RESULTS AND CONCLUSIONS

DNA polymorphisms have a detection limit of 10%. The SRY 'Y-specific' probe has a theoretical detection limit of 1 cell in 10,000. The techniques were applied to investigate survival of male donor cells in an aniridic female patient 2 1/2 years following limbal stem cell grafts. We speculate that low levels of donor-derived cells may still be present. We discuss the advantages and disadvantages of the two approaches, which may have future clinical and experimental application.

The polymerase chain reaction: from functional genomics to high-school practical classes

After a decade of intensive use as an in vitro alternative to cloning DNA, PCR is now well established as the default method for DNA and RNA analysis. Recent developments have consolidated this position by the introduction of more robust formats, improvements in thermal cyclers and labelling and detection methods. The trend is towards increasing automation, although comparatively few diagnostic kits based on PCR are in wide use. At the same time the applications of PCR are being extended with modifications such as long, accurate PCR and arrayed oligonucleotides or expressed sequences.

Monitoring the treatment of developmental dysplasia of the hip with the Pavlik harness. The role of ultrasound

We report the six-year results of a prospective, controlled demographic trial of developmental dysplasia of the hip (DDH) treated in the Pavlik harness using ultrasound supervision. Our aim was to assess the value of ultrasound and its role in monitoring reduction in the harness, in terms of progression or failure of reduction at an early state. From 1988 to 1994, a total of 221 patients with 370 ultrasonographically abnormal hips was treated in the Pavlik harness. This represents a treatment rate for the Southampton district of 5.1 per 1000 live births. Sixteen hips in 12 patients were not reduced in the harness and required surgical treatment; 95.7% were successfully reduced. One case of mild avascular necrosis (0.3%) was identified in those treated by harness alone. Of the 221 patients 87.8% remain under radiological review, with 3.2% of affected hips showing continued, mild acetabular dysplasia. We conclude that ultrasound monitoring has led to an acceptably low level of intervention, a high reduction rate and minimal iatrogenic complications. The trial is continuing.

MONITORING THE TREATMENT OF DEVELOPMENTAL DYSPLASIA OF THE HIP WITH THE PAVLIK HARNESS

We report the six-year results of a prospective, controlled demographic trial of developmental dysplasia of the hip (DDH) treated in the Pavlik harness using ultrasound supervision. Our aim was to assess the value of ultrasound and its role in monitoring reduction in the harness, in terms of progression or failure of reduction at an early state.

From 1988 to 1994, a total of 221 patients with 370 ultrasonographically abnormal hips was treated in the Pavlik harness. This represents a treatment rate for the Southampton district of 5.1 per 1000 live births. Sixteen hips in 12 patients were not reduced in the harness and required surgical treatment; 95.7% were successfully reduced. One case of mild avascular necrosis (0.3%) was identified in those treated by harness alone. Of the 221 patients 87.8% remain under radiological review, with 3.2% of affected hips showing continued, mild acetabular dysplasia.

We conclude that ultrasound monitoring has led to an acceptably low level of intervention, a high reduction rate and minimal iatrogenic complications. The trial is continuing.

Potassium permanganate and tetraethylammonium chloride are a safe and effective substitute for osmium tetroxide in solid-phase fluorescent chemical cleavage of mismatch

Whilst chemical cleavage of mismatch (CCM) detects all point mutations in DNA, its widespread use has been hampered by the complex multistage methodology and the need for toxic chemicals, in particular osmium tetroxide. Here we show that osmium tetroxide can be replaced by potassium permanganate, giving the same spectrum of mutation detection, but with greater sensitivity. The use of potassium permanganate is compatible with solid phase capture and fluorescent detection, giving a safer method of mutation detection. We present here a comparison of CCM with osmium tetroxide and with potassium permanganate, tested on a complete set of single base pair mismatches and a number of small insertion/deletions.

Analysis of the mismatch and insertion/deletion binding properties of Thermus thermophilus, HB8, MutS

The methyl-directed long patch repair pathway in Escherichia coli is involved in increasing the fidelity of replication specific repair of DNA polymerase incorporation errors. This pathway is mediated by three gene products, MutS, MutL, and MutH, which are conserved in higher eukaryotes. Mutations in human homologues of these proteins have been shown to be implicated in hereditary non-polyposis colorectal cancer (HNPCC). A MutS homologue has recently been identified in the extremely thermophilic bacterium, Thermus thermophilus. Here we describe analysis of the binding properties of this protein, which has indicated it can identify all specific base mismatches as well as one, two and three base pair insertion/deletion mutations. We therefore believe this protein may be generally useful for applications involving mismatch detection.

Mapping the minimal domain of hMSH-2 sufficient for binding mismatched oligonucleotides

The human MSH-2 gene product is a member of a highly conserved family of proteins involved in post-replication mismatch repair. Germline mutations in this gene have been implicated in hereditary non-polyposis colorectal cancer (HNPCC). Alterations in the coding region of the hMSH-2 gene result in a mutator phenotype with marked instability of microsatellite sequences, indicative of a deficiency in DNA repair. We have previously shown that a region of high homology between MutS proteins of different species containing a nucleotide binding domain, is sufficient to bind DNA containing specific mismatched residues. In order to determine the minimal domain of hMSH-2 necessary for binding mismatch-containing oligonucleotides, deletion analysis of the C-terminal region was performed. We have constructed a 5' and 3' deletion series, expressed each deletion as a bacterial fusion protein and assessed it for ATPase activity and its ability to identify mismatch containing DNA. Here we demonstrate that a 585 bp fragment encoding 195 amino acids within the C-terminal domain of hMSH-2 is sufficient to bind to DNA containing mismatches.

Changes in the immune system during and after spaceflight

The results of immunological analyses before, during and after spaceflight, have established the fact that spaceflight can result in a blunting of the immune mechanisms of human crew members and animal test species. There is some evidence that the immune function changes in short-term flights resemble those occurring after acute stress, while the changes during long-term flights resemble those caused by chronic stress. In addition, this blunting of the immune function occurs concomitant with a relative increase in potentially infectious microorganisms in the space cabin environment. This combination of events results in an increased probability of inflight infectious events. The realization of this probability has been shown to be partially negated by the judicious use of a preflight health stabilization program and other operational countermeasures. The continuation of these countermeasures, as well as microbial and immunological monitoring, are recommended for continued spaceflight safety.