Efficacy of dasatinib in chronic phase chronic myelogenous leukemia patients after imatinib failure according to baseline BCR- ABL mutations

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Background: Dasatinib is an oral, multi-targeted BCR-ABL and SRC kinase inhibitor with preclinical activity against 20/21 imatinib (Im) resistant BCR-ABL mutations. Clinical efficacy was demonstrated in phase I, II, and III studies in patients (pts) with chronic myelogenous leukemia (CML) in all phases of the disease and BCR-ABL positive acute lymphoblastic leukemia (ALL). We sought to establish a relationship between type of BCR-ABL mutations associated with Im resistance and efficacy of dasatinib in chronic phase (CP) CML pts. Methods: Between 10/03 and 03/06, dasatinib was commenced in 1,093 CP-CML pts recruited for three consecutive trials and administered for a median of 8.7 months (range <1–25.9). BCR-ABL mRNA was screened for mutations of amino acids 207–517 by D-HPLC and/or regular sequencing and data are available from 961 cases (88%). ABL polymorphisms K247R and E499E were excluded from analysis. Results: Prior to dasatinib, 75 different BCR-ABL mutations involving 56 amino acids were detected in 18/240 Im intolerant (7.5%) and 324/721 (45%) Im resistant pts. 267 pts showed one, 53 pts two, 16 pts three, and six pts four mutations. In Im resistant pts, response was not different between 370 pts with and 351 pts without baseline mutations: Complete hematologic response (CHR) was achieved in 89% vs 92%; major cytogenetic response (MCR) in 48% vs 52% being complete (CCR) in 38 vs 36%, respectively. Response dynamics were associated with preclinical activity of dasatinib: classifying mutations for IC50 values <2, 2–20 and >1,000nM (T315I), CHR was achieved in 93, 85 and 28%; MCR in 48, 42 and 0%; and CCR in 37, 35 and 0% of cases, respectively. During follow up, new mutations were detected in 30 cases, predominantly T315I (n=10), Y253H/F (n=4), and F317L (n=3). Conclusions: We conclude that dasatinib is capable of inducing hematologic and cytogenetic remissions in a significant proportion of Im resistant pts associated with BCR-ABL mutations, except T315I, but also in pts with BCR-ABL independent causes of resistance. Quality of response depends on the individual type of the mutation which is consistent with preclinical observations.

No significant financial relationships to disclose.

Rationale for the recommendations for harmonizing current methodology for detecting BCR-ABL transcripts in patients with chronic myeloid leukaemia

Molecular monitoring for patients with chronic myeloid leukaemia (CML) has become an important practice in the era of imatinib therapy. For successful widespread introduction into the mainstream patient monitoring schedule, many procedural aspects of the complex real-time quantitative polymerase chain reaction (RQ-PCR) technique for measuring BCR-ABL transcripts require optimization. Recommendations for harmonizing the differing methodologies have recently been proposed. These recommendations were designed to maximize reliability of analysis for clinical decision making and proposed the adoption of an International Scale of measurement. The purpose of this review is to present the evidence and supporting data for specific recommendations. These recommendations include use of the same source of cells, either blood or marrow, for analysis; for validation of equal PCR amplification efficiencies of cDNA and standards when using a plasmid to construct standard curves and for ensuring ongoing high-level performance by undertaking a quality assurance programme. Clinicians must know the measurement reliability of an RQ-PCR assay to be able to determine the significance of a change in BCR-ABL level. An assay with poor precision limits the clinical usefulness of results. International harmonization should establish RQ-PCR measurement of BCR-ABL as the best method for monitoring treatment response for patients with CML.

A phase II study of AMN107, a novel inhibitor of Bcr-Abl, administered to imatinib-resistant or intolerant patients (pts) with Ph+ chronic myelogenous leukemia (CML) in blast crisis (BC) or relapsed/refractory Ph+ acute lymphoblastic leukemia (ALL)

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Background: AMN107 is a highly selective, aminopyrimidine which is 30-fold more potent in vitro than imatinib and active against 32/33 imatinib resistant Bcr-Abl mutations. Methods: This open-label study evaluated safety and efficacy of AMN107 (400 mg bid) by hematologic/cytogenetic response (HR/CyR) rates in imatinib resistant/ intolerant BC or relapsed/refractory ALL pts. Results: Preliminary data from this ongoing study are presented for 18 BC and 6 ALL (5 relapsed/refractory, 1 minimal residual disease) pts. Baseline mutation data are available for 6 BC and 2 ALL pts: 2 and 1, respectively, had Bcr-Abl mutations. The overall median age was 54 yrs and the overall median exposure was 84 days. Seven patients remain on treatment (5 BC, 2 ALL) and 17 discontinued (3 adverse events, 9 progressive disease (PD), 3 deaths, 2 other). Two BC pts died of PD. 1 ALL pt had sudden cardiac death. HR was reported in 7 (38%) BC pts; 5 complete HR and 2 marrow responses/no evidence of leukemia. 3 BC pts had CyR (2 complete, 1 minor). Complete remission was reported in 2 (33%) ALL (1 relapsed/refractory and 1 MRD) pts. Adverse events in ≥ 10% were rash in 9 (37%) pts, thrombocytopenia in 8 (33%) pts (Gr 3/4 in 7 (29%), nausea in 7 (29%) pts, pyrexia in 7 (29%) pts (Gr 3/4 in 2 (8%)); vomiting in 7 (29%) pts (Gr 3/4 in 1 (4%), diarrhea, fatigue in 6 (25%) pts each, headache in 6 (25%) pts (Gr 3/4 in 1 (4%)), neutropenia in 6 (25%) pts (all Gr 3/4), anemia in 5 (21%) pts (Gr 3/4 in 4 (17%)), pain in extremity in 5 (21%) pts (Gr 3/4 in 1 (4%)), pain, peripheral edema in 4 (17%) pts each, pruritus in 4 (17%) pts (Gr 3/4 in 1 (4%)), leukocytosis in 3 (13%) pts (Gr 3/4 in 1 (4%)), arthralgia, pharyngolaryngeal pain, and upper abdominal pain 3 (13%) each. Conclusions: AMN107 has clinical activity and an acceptable safety and tolerability profile in pts with imatinib-resistant or intolerant BC and relapsed/refractory Ph+ ALL pts

[Table: see text]

Speech and language therapy for dysarthria due to non-progressive brain damage

BACKGROUND

Dysarthria is a common sequel of non-progressive brain damage (typically stroke and traumatic brain damage). Impairment-based therapy and a wide variety of compensatory management strategies are undertaken by speech and language therapists with this patient population.

OBJECTIVES

To determine the efficacy of speech and language therapy interventions for adults with dysarthria following non-progressive brain damage.

SEARCH STRATEGY

We searched the trials registers of the following Cochrane Groups: Stroke, Injuries, Movement Disorders and Infectious Diseases. We also searched the trials register of the Cochrane Rehabilitation and Related Therapies Field. The trials registers were last searched in September 2004. The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2004), MEDLINE (1966 to September 2004), EMBASE (1980 to September 2004), CINAHL (1983 to September 2004), PsycINFO (1974 to October 2004), and Linguistics and Language Behavior Abstracts (1983 to December 2004) were searched electronically. We handsearched the International Journal of Language and Communication Disorders (1966 to 2005, Issue 1) and selected conference proceedings, and scanned the reference lists of relevant articles. We approached colleagues and speech and language therapy training institutions to identify other possible published and unpublished studies.

SELECTION CRITERIA

Unconfounded randomised controlled trials (RCTs).

DATA COLLECTION AND ANALYSIS

One author assessed trial quality. Two co-authors were available to examine any potential trials for possible inclusion in the review.

MAIN RESULTS

No trials of the required standard were identified.

AUTHORS' CONCLUSIONS

There is no evidence of the quality required by this review to support or refute the effectiveness of speech and language therapy interventions for dysarthria following non-progressive brain damage. Despite the recent commencement of a RCT of optimised speech and language therapy for communication difficulties after stroke, there continues to be an urgent need for good quality research in this area.

Epigenetic influences may explain dental differences in monozygotic twin pairs

BACKGROUND

Comparisons between monozygotic (MZ) co-twins have tended to focus on the similarities between their dentitions rather than differences. The aim of this study was to determine the prevalence of discordant expression for simple hypodontia and supernumerary teeth in MZ twin pairs and to explain how phenotypic differences might occur despite their similar genotypes.

METHODS

Records of 278 pairs of MZ twins, including dental casts and radiographs, were examined and the prevalences of discordant expression for missing upper lateral incisors (ULI) or second premolars (PM2), and of mesiodentes, were determined. Zygosities were confirmed by comparisons of blood markers and DNA.

RESULTS

There was evidence of at least one missing ULI or PM2 in 24 of the 278 MZ pairs (8.6 per cent), with 21 of these 24 pairs (87.5 per cent) showing discordant expression. Nine of the 278 MZ pairs (3.2 per cent) displayed evidence of mesiodentes, with eight of these nine pairs (88.9 per cent) being discordant.

CONCLUSION

Our findings show that differences in the expression of missing or extra teeth occur often between MZ co-twins whose genetic make-up predisposes them to simple hypodontia or mesiodentes. We postulate that minor variations in epigenetic events during odontogenesis may account for these distinct differences.

Interferon-alpha-2b and oral cytarabine ocfosfate for newly diagnosed chronic myeloid leukaemia

BACKGROUND

Treatment with interferon and subcutaneous cytarabine produces superior cytogenetic responses in chronic myeloid leukaemia (CML) than treatment with interferon alone, but at the expense of greater toxicity. Cytarabine ocfosfate (YNK01) is an oral precursor of cytarabine that may overcome some of the inconvenience and toxicities associated with subcutaneous cytarabine administration.

PATIENTS AND METHODS

We studied the efficacy and tolerability of combination therapy with interferon-alpha-2b and YNK01 in patients with newly diagnosed, untreated CML. Forty patients were treated with interferon-alpha-2b (5 MU/m2/day) plus monthly courses of YNK01 (600 mg/day for 10 days) for 1 year.

RESULTS

The 6-month complete haematological response rate was 63% and the 1-year major cytogenetic response rate was 30%, with 10% of cytogenetic responses being complete. With a median follow-up of 57 months, the estimated 5-year overall survival was 86% (95% confidence interval 70% to 94%). Treatment tolerability was poor, with toxicity leading to discontinuation of one or both drugs in 60% of cases. The median daily dose of interferon alpha-2b was 7.75 MU and the median dose of YNK01 was 600 mg/day for each 10-day treatment cycle.

CONCLUSIONS

Interferon-alpha-2b and YNK01 produce cytogenetic responses comparable to those achieved with interferon-alpha-2b and parenteral cytarabine, although toxicity was excessive. Alternate dosing strategies may enhance the tolerability of YNK01.

Association of frontal sinus development with somatic and skeletal maturation in Aboriginal Australians: a longitudinal study

There have been very few studies of frontal sinus development and its association with other growth parameters in humans. The aim of this study was to investigate the relationship of frontal sinus development with somatic and skeletal maturation in a sample of Aboriginal Australians. The sample comprised 31 individuals, of whom 17 were males and 14 females. For the selected subjects the following records were available: lateral head radiographs, hand-wrist radiographs and stature recordings, generally covering the age range from 7 to 18 years. Descriptive statistics for frontal sinus size, skeletal ossification and body height were calculated at yearly intervals and comparisons made between the sexes. Growth velocities in frontal sinus height, frontal sinus depth and stature were also calculated for both sexes. The frontal sinus was found to display a well-defined adolescent growth spurt, with its peak velocity occurring after the peak velocity in body height. Females were found to attain peak velocity in sinus height earlier, on average, than males but they attained peak velocity in sinus depth at a similar age to males. The sequence of hand-wrist ossification events followed a similar pattern in both sexes, with events in females occurring approximately one year earlier than those in males. These results indicate that an adolescent spurt is present in frontal sinus growth and that the spurt tends to occur after statural velocity has peaked. Hand-wrist ossification events also tend to have a close relationship to peak statural and frontal sinus velocity and these relationships may be useful in clinical situations for predictive purposes.

Germinoma with synchronous involvement of the pineal gland and the suprasellar region: a treatable cause of visual failure in a young adult

Germinomas constitute 0.1-3.4% of all intracranial tumours and 90% affect patients less than 20 years old. Although they are relatively aggressive tumours, which commonly invade the surrounding tissue and seed within the central nervous system, they are very radiosensitive and carry a favourable prognosis. We describe a 19-year-old man who presented with bilateral visual failure secondary to a germinoma with synchronous involvement of the pineal gland and the suprasellar region. Radiotherapy restored his vision almost back to normal.

Withholding and withdrawal of therapy in patients with acute renal injury: a retrospective cohort study

The incidence of withholding and withdrawal of therapy in the setting of multi-organ failure in critically ill patients has increased. Epidemiological data on the decision-making process of withholding or withdrawal of therapy from Australian and New Zealand intensive care units is sparse. We examined the clinical and electronic records of 179 consecutive patients, admitted to the ICU between 1st January 2000 and 31st December 2001, who had acute renal injury. Acute renal replacement therapy was offered in 11.2% of patients. Therapy was withheld or withdrawn in 21.2% of patients. The levels of supportive care were comparable between those who had therapy withheld or withdrawn and those who had full intensive care therapy until such a decision was made. Predicted mortality (OR 1.04, 95% CI: 1.01-1.08, P = 0.03) and age (OR 1.04, 95% CI: 1.00-1.08, P = 0.03) were independently associated with the decision to withhold or withdraw therapy. The mean ICU stay of those with withdrawal or withholding of therapy was much shorter than those with full therapy (2.5 vs 5.7 days). This was likely to be due to an older age of our cohort, rapid progressive nature of the acute disease, a different clinical approach to treating critically ill elderly patients, or a combination of these factors. This pattern of practice was quite different from those reported from ICUs in other parts of the world. A prospective multi-centre observational study will clarify the pattern of practice in this important area of intensive care practice in Australasia.

Oral versus intravenous ganciclovir for the prophylaxis of cytomegalovirus disease after allogeneic bone marrow transplantation

BACKGROUND

Prophylactic low dose i.v. ganciclovir in patients at risk after allogeneic bone marrow transplantation (BMT) is highly effective in the prevention of cytomegalovirus (CMV) disease and infection.

AIM

In this study, we sought to assess the tolerability of oral ganciclovir in patients after allogeneic BMT.

METHODS

CMV seropositive patients or those with CMV seropositive donors were randomised to be treated with i.v. ganciclovir 5 mg/kg three times weekly or oral ganciclovir 3 g daily from engraftment to day 84. The period of accrual was from May 1997 to October 1998. Patients were monitored for CMV infection by weekly serology. Thirty-one patients received oral ganciclovir and 27 patients received i.v. ganciclovir, the treatment groups being balanced for clinical characteristics and prognostic factors.

RESULTS

Renal dysfunction, transfusion requirements and significant nausea and vomiting were not different. There were no documented cases of CMV disease during the study period although three patients developed CMV polymerase chain reaction positivity at various times. One patient treated with i.v. ganciclovir developed non-fatal gastrointestinal CMV disease after the study period on day 108. Eight patients in the oral group failed to complete planned therapy, whereas two patients failed to complete the i.v. course.

CONCLUSION

We conclude that oral ganciclovir is a reasonable, well-tolerated alternative to i.v. ganciclovir for the prophylaxis of CMV disease after allogeneic BMT.

Treatment for swallowing difficulties (dysphagia) in chronic muscle disease

BACKGROUND

The management of dysphagia (difficulty in swallowing), a common complication of long-term progressive muscle disease in children and adults, is currently unclear.

OBJECTIVES

Our objective was to determine the most appropriate intervention for dysphagia in people with chronic, untreatable, non-inflammatory muscle disease.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group trials register, Cochrane Central Register of Controlled Trials (Cochrane Library Issue 2, 2003), MEDLINE (from January 1966 to Week 2 June 2003), EMBASE (from January 1980 to Week 2 June 2003), AMED (from January 1985 to Week 2 June 2003), LILACS (from January 1982 to June 21 2003) and CINAHL (from January 1982 to Week 2 June 2003) and contacted authors of published studies and other experts.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials of adults and children with chronic untreatable non-inflammatory muscle disease. The interventions under review included dietary modification, swallowing manoeuvres, a range of surgical interventions and enteral feeding. Our primary outcome was stabilisation of previously documented progressive weight loss not attributable to any other cause or weight gain of at least 5 kg in adults or increase in weight to at least the 10th centile in children, maintained for at least six months following the intervention. Secondary outcomes were: reduction in laryngeal penetration of bolus and/or aspiration observed on videofluoroscopy (modified barium swallow), reduction in chest infections attributable to aspiration over a six-month period, improvement in quality of life using a validated rating scale, the proportion of subjects who refused the intervention, the proportion of carers who refused the intervention, and serious adverse events related to the intervention within the first twelve months after intervention.

DATA COLLECTION AND ANALYSIS

We identified no randomised controlled trials. We identified seven case series reporting the results of surgical intervention for moderate to severe dysphagia, and one reporting on the outcome of feeding advice and enteral feeding in children with a congenital myopathy.

MAIN RESULTS

No studies were found that fulfilled the inclusion criteria. Therefore it was not possible to determine the benefit or otherwise of surgical intervention (cricopharyngeal myotomy or upper oesophageal dilatation) for oculopharyngeal muscular dystrophy or other chronic progressive muscle diseases, and dietary advice or enteral feeding for children with congenital myopathy, compared with no intervention or an alternative intervention.

REVIEWERS' CONCLUSIONS

There are no trials that have adequately evaluated treatments in the management of dysphagia for chronic muscle disease. It is therefore not possible to decide on the most appropriate treatment for a given individual based on current evidence.

The value of twins in dental research

Due to recent advances in molecular genetics, studies of twins will continue to provide important insights into how genetic and environmental factors contribute to variation in human physical and behavioural traits and disorders. This review emphasizes that biometrical genetic studies of twins are particularly valuable in complementing and directing molecular approaches to facilitate the detection of quantitative trait loci. It also describes several other research models involving twins, apart from the traditional comparison of similarities in monozygotic (identical) and dizygotic (non-identical) pairs, that have the potential to provide new information in the future. Current knowledge about the genetic bases of common dental problems is summarized and future directions in dental research involving twins are outlined.

Fetal muscle gene transfer is not enhanced by an RGD capsid modification to high-capacity adenoviral vectors

High levels of alpha(v) integrin expression by fetal muscle suggested that vector re-targeting to integrins could enhance adenoviral vector-mediated transduction, thereby increasing safety and efficacy of muscle gene transfer in utero. High-capacity adenoviral (HC-Ad) vectors modified by an Arg-Gly-Asp (RGD) peptide motif in the HI loop of the adenoviral fiber (RGD-HC-Ad) have demonstrated efficient gene transfer through binding to alpha(v) integrins. To test integrin targeting of HC-Ad vectors for fetal muscle gene transfer, we compared unmodified and RGD-modified HC-Ad vectors. In vivo, unmodified HC-Ad vector transduced fetal mouse muscle with four-fold higher efficiency compared to RGD-HC-Ad vector. Confirming that the difference was due to muscle cell autonomous factors and not mechanical barriers, transduction of primary myogenic cells isolated from murine fetal muscle in vitro demonstrated a three-fold better transduction by HC-Ad vector than by RGD-HC-Ad vector. We hypothesized that the high expression level of coxsackievirus and adenovirus receptor (CAR), demonstrated in fetal muscle cells both in vitro and in vivo, was the crucial variable influencing the relative transduction efficiencies of HC-Ad and RGD-HC-Ad vectors. To explore this further, we studied transduction by HC-Ad and RGD-HC-Ad vectors in paired cell lines that expressed alpha(v) integrins and differed only by the presence or absence of CAR expression. The results increase our understanding of factors that will be important for retargeting HC-Ad vectors to enhance gene transfer to fetal muscle.

Molar intercuspal dimensions: genetic input to phenotypic variation

Molecular studies indicate that epigenetic events are important in determining how the internal enamel epithelium folds during odontogenesis. Since this process of folding leads to the subsequent arrangement of cusps on molar teeth, we hypothesized that intercuspal distances of human molar teeth would display greater phenotypic variation but lower heritabilities than overall crown diameters. Intercuspal distances and maximum crown diameters were recorded from digitized images of dental casts in 100 monozygotic and 74 dizygotic twin pairs. Intercuspal distances displayed less sexual dimorphism in mean values but greater relative variability and fluctuating asymmetry than overall crown measures. Correlations between intercuspal distances and overall crown measures were low. Models incorporating only environmental effects accounted for observed variation in several intercuspal measures. For those intercuspal variables displaying significant additive genetic variance, estimates of heritability ranged from 43 to 79%, whereas those for overall crown size were higher generally, ranging from 60 to 82%. Our finding of high phenotypic variation in intercuspal distances with only moderate genetic contribution is consistent with substantial epigenetic influence on the progressive folding of the internal enamel epithelium, following formation of the primary and secondary enamel knots.

Unique case of mosaicism involving two morphologically similar marker chromosomes of different centric origin in a patient with developmental delay

A five-year-old Caucasian male presented with developmental delay, minor dysmorphic features, and hyperactivity. Cytogenetic analysis showed the presence of a marker chromosome in the majority of cells analyzed. Fluorescence in situ hybridization (FISH) analyses using several alpha satellite probes, including D13Z1/D21Z1, did not reveal any signal on the marker chromosome. Subsequent multicolor FISH (M-FISH) indicated the marker to be derived from chromosome 13, and FISH with a chromosome 13 paint confirmed this finding. The absence of D13Z1/D21Z1 signal on the marker suggested that it was analphoid in nature. Comparative genomic hybridization (CGH) was utilized to further characterize the region of chromosome 13 from which the marker originated, and unexpectedly revealed a gain of chromosomal material at both the centromeric regions of chromosomes 3 and 13. In view of the CGH results, extensive FISH studies with D3Z1 and D13Z1/D21Z1 were performed and revealed the presence of four cell lines comprising one normal cell line (50.5%), a cell line with a chromosome 3 derived marker (19%), a cell line containing a marker derived from chromosome 13 (20%), and a cell line with both markers (10.5%). As the two markers appeared morphologically similar by GTG banding, all 47,XY metaphases in the initial analysis were thought to comprise only a single marker. This is the first report, to our knowledge, of the presence of a chromosome 3 and a chromosome 13 marker in mosaic condition in a congenital disorder. In light of our experience, we urge caution in interpreting karyotypes with marker chromosomes. Our case illustrates the limitations of fluorescent DNA probes and sampling errors.

Speech and language therapy for dysarthria due to non-progressive brain damage

BACKGROUND

Dysarthria is a common sequel of non-progressive brain damage (typically stroke and traumatic brain damage). Impairment-based therapy and a wide variety of compensatory management strategies are undertaken by speech and language therapists with this patient population.

OBJECTIVES

To determine the efficacy of speech and language therapy interventions for adults with dysarthria following non-progressive brain damage.

SEARCH STRATEGY

This review has drawn on the search strategies developed for the following Cochrane Groups as a whole: Stroke, Injuries, Movement Disorders and Infectious Diseases. Relevant trials were identified in the Specialised Registers of Controlled Trials (see Review Group details for more information). We also searched the trials register of the Cochrane Rehabilitation and Related Therapies Field. The Trials Registers were last searched in December 2001. The Cochrane Controlled Trials Register (Cochrane Library 2002, Issue 1), MEDLINE (1966-December 2001), EMBASE (1980-December 2001), CINAHL (1983-December 2001), PsycINFO (1974-February 2002) and Linguistics and Language Behavior Abstracts (1983-October 2001) were searched electronically. We handsearched the International Journal of Language and Communication Disorders (1966-2002, Issue 1) and selected conference proceedings, and scanned the reference lists of relevant articles. Colleagues were approached to identify other possible published and unpublished studies.

SELECTION CRITERIA

Unconfounded randomised controlled trials.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality. Two co-reviewers were available to examine any potential trials for possible inclusion in the review.

MAIN RESULTS

No trials of the required standard were identified.

REVIEWER'S CONCLUSIONS

There is no evidence of the quality required by this review to support or refute the effectiveness of Speech and Language Therapy interventions for dysarthria following non-progressive brain damage. There is an urgent need for good quality research in this area.

A study of occlusal variation in the primary dentition of Australian twins and singletons

In this study, we quantified the extent of variation in different occlusal features of Australian children of European descent with complete primary dentitions, but no permanent teeth present in the mouth. The study group consisted of 412 individuals, aged between 3 and 7 years, including 70 monozygous (MZ) twin pairs, 68 same-sexed dizygous (DZ) twin pairs, 11 opposite-sexed DZ twin pairs, and 114 singletons. Occlusal traits, including inter-dental spacing, incisal overbite and overjet, arch breadth and arch depth, were obtained directly from dental casts or indirectly from photocopies or impressions of the casts. Descriptive statistics summarised the data and indicated that distributions were similar to those published for other populations. Univariate genetic analysis, using the structural equation modelling package Mx, was carried out on the quantitative data using the normal assumptions of the twin model. Genetic modelling indicated that a model incorporating additive genetic (A) and unique environmental variation (E) was the most parsimonious for interdental spacing, overbite, overjet and arch dimensions. Estimates of heritability for interdental spacing ranged from 0.62 to 0.81. Estimates for overbite and overjet were 0.53 and 0.28, respectively, and estimates for arch dimensions ranged from 0.69 to 0.89. These results indicated a moderate to relatively high genetic contribution to observed variation.

Effect of Down syndrome on the dimensions of dental crowns and tissues

Abnormal growth in Down syndrome (DS) is reflected by variable reduction in size and simplification in form of many physical traits. This study aimed to compare the thickness of enamel and dentine in deciduous and permanent mandibular incisor teeth between DS and non-DS individuals and to clarify how these tissues contribute to altered tooth size in DS. Sample groups comprised 61 mandibular incisors (29 permanent and 32 deciduous) from DS individuals and 55 mandibular incisors (29 permanent and 26 deciduous) from non-DS individuals. Maximum mesiodistal and labiolingual crown dimensions were measured initially, then the crowns were sectioned midsagittally and photographed using a stereomicroscope. Linear measurements of enamel and dentine thickness were obtained on the labial and lingual surfaces of the crowns, together with enamel and dentine-pulp areas and lengths of the dentino-enamel junction. Reduced permanent crown size in DS was associated with a reduction in both enamel and dentine thickness. After adjustments were made for tooth size, DS permanent incisors had significantly thinner enamel than non-DS permanent teeth. The DS permanent teeth also exhibited significant differences in shape and greater variability in dimensions than the non-DS permanent teeth. Crown dimensions of deciduous incisors were similar in size or larger in DS compared with non-DS deciduous teeth. Enamel and dentine thicknesses of the deciduous teeth were similar in DS and non-DS individuals. The findings indicate that growth retardation in DS reduces both enamel and dentine deposition in the permanent incisors but not in the earlier-forming deciduous predecessors. The results are also consistent with the concept of amplified developmental instability for dental traits in DS.

The sonic hedgehog receptor patched associates with caveolin-1 in cholesterol-rich microdomains of the plasma membrane

The Hedgehog signaling pathway is involved in early embryonic patterning as well as in cancer; however, little is known about the subcellular localization of the Hedgehog receptor complex of Patched and Smoothened. Since Hh has been found in lipid rafts in Drosophila, we hypothesized that Patched and Smoothened might also be found in these cholesterol-rich microdomains. In this study, we demonstrate that both Smoothened and Patched are in caveolin-1-enriched/raft microdomains. Immunoprecipitation studies show that Patched specifically interacts with caveolin-1, whereas Smoothened does not. Fractionation studies show that Patched and caveolin-1 can be co-isolated from buoyant density fractions that represent caveolae/raft microdomains and that Patched and caveolin-1 co-localize by confocal microscopy. Glutathione S-transferase fusion protein experiments show that the interaction between Patched and caveolin-1 involves the caveolin-1 scaffolding domain and a Patched consensus binding site. Immunocytochemistry data and fractionation studies also show that Patched seems to be required for transport of Smoothened to the membrane. Depletion of plasmalemmal cholesterol influences the distribution of the Hh receptor complex in the caveolin-enriched/raft microdomains. These data suggest that caveolin-1 may be integral for sequestering the Hh receptor complex in these caveolin-enriched microdomains, which act as a scaffold for the interactions with the Hh protein.

Evaluation of the role of proline residues flanking the RGD motif of dendroaspin, an inhibitior of platelet aggregation and cell adhesion

The effect of a panel of proline mutants of dendroaspin, an inhibitor of platelet aggregation and cell adhesion, including A(42)-dendroaspin, A(47)-dendroaspin, A(49)-dendroaspin, A(42,47)-dendroaspin and A(47,49)-dendroaspin, was investigated using platelet-aggregation and cell-adhesion assays. Here we show that a single alanine-for-proline substitution did not affect potency when measured as the ability either to inhibit platelet aggregation induced by ADP (IC(50) approximately 170 nM) or to block transfected A375-SM cell adhesion to fibrinogen in the presence of Mn(2+) as compared with wild-type dendroaspin. By comparison, double proline substitution with alanines significantly reduced the potency in both assays by approx. 5-8-fold. These observations, therefore, suggest that proline residues flanking the RGD motif in dendroaspin and other RGD-containing venom proteins, e.g. disintegrins, may contribute to maintaining a favourable conformation for the solvent-exposed RGD site for its recognition by integrin receptors.