3D Surface Imaging in Reducing Setup Error for Prone Whole Breast Radiotherapy

PURPOSE/OBJECTIVE(S)

For patients undergoing whole breast radiotherapy, treatment in the prone position allows for reduced dose to critical organs such as the heart and lungs. However, this treatment position comes with greater challenges in reproducibility and setup error given the unstable position. Our objective was to investigate the benefit of using 3D surface imaging to reduce daily setup errors for these patients.

MATERIALS/METHODS

We performed a retrospective review of consecutive breast patients receiving prone breast radiotherapy at our institution. All patients were positioned initially using setup tattoos and twice a week, the positioning was adjusted using the aid of a motion tracking system. Then, a daily kilovoltage (kV) cone beam computed tomography (CBCT) image was acquired and positioning was adjusted to setup the breast and chest wall. Shifts in each translational direction were recorded and the three-dimensional vector displacement was calculated. For each patient the average displacements on days where a motion tracking system was used were compared to days whereas motion tracking system was not used. Patients were classified into significant benefit (more than 4 mm improvement), small benefit (0-4 mm improvement) or increased error (increased shifts on days a motion tracking system was used). Patient demographics were collected including stage, BMI, weight, heigh, age, ethnicity. Comparisons were made using t-tests.

RESULTS

A total of 40 patients with stage T0-2N0 breast cancer were included. The median age was 64 and 60% of patients had left sided breast cancer. A total of 665 daily CBCT scans were analyzed, and the median daily vector displacement was 7.2 mm (1-21 mm). The median displacement on treatments where a motion tracking system was used (41% of treatments) was 6.1 mm versus 8.1 mm when not used (p<.0001). The use of a motion tracking system significantly reduced the occurrence of shifts more than 1 cm (12% vs. 33%, p < .0001) and 5 mm (65% vs. 83% p < .0001). For individual patients, 28% showed a significant improvement, 55% showed small improvement, 17% showed increased error. The median BMI was 27, weight was 71 kg, and neither was associated with an improvement in the use of Align RT (p > .05). However, patients in the small improvement group had a higher BMI than patients in the other two groups 29 vs. 25 (p = .01). A similar association was seen for weight (p < .05). No association was found for the benefit of a motion tracking system for height, age, stage or ethnicity.

CONCLUSION

The use of 3D surface imaging for breast cancer patients receiving prone whole breast radiotherapy on average significantly reduced setup errors. For patients with higher BMI there was a consistent small reduction in setup error when compared to using setup marks alone. For patients with lower BMI, caution should be exercised as there was more variation with some patients demonstrating a large benefit and other patients having an increased setup error with the use of surface imaging. Further research is needed to investigate on the optimal use of this technology.

Abstract P6-19-03: The role of lumpectomy and radiation therapy in men 70 years of age and older with early breast cancer on hormone therapy: A NCDB analysis

Background: Current consensus guidelines for the treatment of male breast cancer are driven by female-only clinical trials despite data suggesting distinct biologic, clinicopathologic, and prognostic differences between male and female breast cancer patients. This includes a recent retrospective multicenter analysis showing greater overall survival among male breast cancer patients who underwent lumpectomy with radiation therapy (RT), compared to total mastectomy or lumpectomy alone. In light of these findings and the CALGB 9343 trial performed in women, we sought to evaluate if survival was also equivalent in men ≥70 years old with early stage breast cancer treated with hormone therapy and lumpectomy with or without radiation therapy (RT), as shown in women.

Methods: We performed a retrospective analysis of 752 stage I (T1N0M0), estrogen receptor (ER) positive male breast cancer patients ≥70 years of age who were treated with hormone therapy and underwent lumpectomy with or without RT or total mastectomy (without RT) from the National Cancer Database (NCDB) between the years 2004 to 2014. Chi-squared, Kruskal-Wallis, and analysis of variance tests were used to compare demographic and clinicopathologic differences between groups. Multivariable Cox proportional hazards regression analysis was used to compare overall survival between treatment groups, controlling for demographic and clinicopathologic differences.

Results: Most patients underwent total mastectomy (67.4%), with only 32.6% treated with lumpectomy. Of those who underwent lumpectomy, 72.6% (n=178) underwent adjuvant RT. There were significant differences in age, tumor size, histology, grade, surgical margins, nodal surgery, and chemotherapy between patients who underwent lumpectomy without RT, lumpectomy with RT, and total mastectomy (p&lt;0.05). Lumpectomy without RT patients were older (78.9 vs. 76.0 & 76.9 years, p&lt;0.01), more frequently presented with invasive ductal carcinoma (77.6% vs. 71.3% & 85.4%, p&lt;0.0001), and less frequently underwent axillary nodal surgery including sentinel lymph node biopsy (71.7% vs. 91.6% & 94.9%, p&lt;0.0001) compared to lumpectomy with RT and total mastectomy patients. In multivariate analysis, there were no significant differences in overall survival for lumpectomy without RT, lumpectomy with RT (HR 0.71, 95%CI 0.39-1.27, p=0.25), and total mastectomy alone (HR 0.92, 95%CI 0.55-1.56, p=0.76). Older age, higher Charlson-Deyo comorbidity scores, and poorly differentiated tumors were associated with poorer overall survival, while treatment at an academic/research center was associated with improved overall survival (p&lt;0.05).

Conclusion: In this national sample of elderly ER positive male breast cancer patients with early disease on hormone therapy, lumpectomy alone was associated with equivalent survival compared to lumpectomy with RT and total mastectomy alone. These results suggest that breast conserving surgery without radiation therapy is appropriate for this subset of male breast cancer patients and greater adoption by breast surgeons should be considered.

Citation Format: Bateni SB, Arora M, Daly ME, Bold RJ, Canter RJ, Sauder CA. The role of lumpectomy and radiation therapy in men 70 years of age and older with early breast cancer on hormone therapy: A NCDB analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-19-03.

The Prothrombin 20210A Allele and Its Association with Myocardial Infarction

The relationship between the prothrombin (PT) 20210A allele and arterial disease is controversial. We conducted a case-control study to assess its contribution to risk of myocardial infarction (MI). Five hundred and thirty-nine acute MI patients and 498 control subjects aged <75 years were studied. Two percent of cases carried the PT20210A allele compared to 2.8% of controls. The odds ratio for MI was 0.72 (95% CI 0.32-1.60) indicating that the PT20210A allele confers no increased risk for MI. Subgroup analysis showed no association between the PT20210A allele and either premature MI or MI in females. We conclude the PT20210A allele is not a risk factor for MI and suggest that discrepancies in studies relating the PT20210A allele to MI may be due to difficulties in estimating its low allelic frequency in the general population and thus random differences in the observed frequencies in the control populations studied.

Major Structural Defects in the Antithrombin Gene in Four Families with Type I Antithrombin Deficiency

The molecular basis of quantitative antithrombin deficiency was investigated in four families predicted to have major antithrombin gene rearrangements. A 1,442 bp deletion and insertion of the sequence 5’T(n = 38-40)GAGACG was characterised in one case. Sequence surrounding the breakpoints contained two perfect, and one imperfect, inverted repeats which may have mediated formation of a stem loop structure on one strand during DNA replication potentiating the deletion. A 9,219 bp deletion spanning introns 2 to 5 was identified in a second family. The identical 6 bp sequence was upstream of each breakpoint and the 5’ breakpoint was located in a sequence of the Alu 3 repeat predicted to be susceptible to strand breakage during transcription. This may have promoted misalignment, and deletion, of one of the repeats and the intervening DNA. A novel 1.8 kb antithrombin gene fragment was present in DNA digests from affected members of the third family suggesting a partial antithrombin gene duplication event while in the remaining family, evidence supporting a complete gene deletion was obtained.

Antithrombin Cambridge II (Ala384Ser): Clinical, Functional and Haplotype Analysis of 18 Families

Thirty-one individuals from 18 unrelated families with antithrombin deficiency have been identified as having a single point mutation within codon 384 (13268 GCA→TCA) resulting in an alanine to serine substitution. Six families (11 individuals) were identified by the screening of individuals with thromboembolic disease or with a family history of thromboembolic disease, whilst the remaining 12 families (20 individuals) were identified by screening of asymptomatic blood donors. Four individuals had a history of venous thrombotic disease, a further 2 gave a history of superficial thrombophlebitis but the remaining 25 individuals were asymptomatic. Affected individuals demonstrated normal immunological levels of antithrombin but a decrease in anti-IIa activity in the presence of heparin. Haplotype analysis was used to examine the possibility of a founder effect to explain the high frequency of this non-CpG mutation. 29/31 individuals showed a single common “core” haplotype, the only variation existing in the number of copies of an (ATT)n repeat polymorphism – 13, 14, 15 or 17. The results suggest that at most there are four independent origins for this mutation.

A Novel Mutation in Intron K of the PROS1 Gene Causes Aberrant RNA Splicing and Is a Common Cause of Protein S Deficiency in a UK Thrombophilia Cohort

In the course of investigating the molecular basis of protein S deficiency in 31 index cases with thrombophilia, we identified seven kindred where the underlying defect was a novel A to G transition 9 bp upstream of exon 12 in intron K of the PROS1 gene. In all but one case, the mutation caused type I deficiency. One individual had type III deficiency. While ectopic transcript analysis using the BstXI dimorphism in exon 15 failed to detect a transcript from the mutated allele, analysis of transcripts spanning exons 11 and 12 revealed a minor mRNA species. Sequencing confirmed the mutation created a new RNA acceptor site introducing 8 nucleotides of intronic sequence into the mature mRNA. Haplotype analysis of the defective PROS1 alleles in six families revealed the same haplotype in all affected individuals suggesting the presence of a common ancestor. Six of the fourteen relatives with the mutation experienced at least one venous thrombotic event strongly supporting the association of the mutation with venous thrombosis.

Use of next-generation sequencing and candidate gene analysis to identify underlying defects in patients with inherited platelet function disorders

BACKGROUND

Inherited platelet function disorders (PFDs) are heterogeneous, and identification of the underlying genetic defects is difficult when based solely on phenotypic and clinical features of the patient.

OBJECTIVE

To analyze 329 genes regulating platelet function, number, and size in order to identify candidate gene defects in patients with PFDs.

PATIENTS/METHODS

Targeted analysis of candidate PFD genes was undertaken after next-generation sequencing of exomic DNA from 18 unrelated index cases with PFDs who were recruited into the UK Genotyping and Phenotyping of Platelets (GAPP) study and diagnosed with platelet abnormalities affecting either Gi signaling (n = 12) or secretion (n = 6). The potential pathogenicity of candidate gene defects was assessed using computational predictive algorithms.

RESULTS

Analysis of the 329 candidate PFD genes identified 63 candidate defects, affecting 40 genes, among index cases with Gi signaling abnormalities, while 53 defects, within 49 genes, were identified among patients with secretion abnormalities. Homozygous gene defects were more commonly associated with secretion abnormalities. Functional annotation analysis identified distinct gene clusters in the two patient subgroups. Thirteen genes with significant annotation enrichment for 'intracellular signaling' harbored 16 of the candidate gene defects identified in nine index cases with Gi signaling abnormalities. Four gene clusters, representing 14 genes, with significantly associated gene ontology annotations were identified among the cases with secretion abnormalities, the most significant association being with 'establishment of protein localization.'

CONCLUSION

Our findings demonstrate the genetic complexity of PFDs and highlight plausible candidate genes for targeted analysis in patients with platelet secretion and Gi signaling abnormalities.

Helical tomotherapy with simultaneous integrated boost dose painting for the treatment of synchronous primary cancers involving the head and neck

OBJECTIVE

To demonstrate the feasibility of helical tomotherapy (HT)-based intensity-modulated radiotherapy (IMRT) for the treatment of synchronous primary cancers arising from the head and neck.

METHODS

14 consecutive patients with histologically proven squamous cell carcinoma of the head and neck were determined to have a second primary cancer in the upper aerodigestive tract on further evaluation and were treated with HT using simultaneous integrated boost IMRT. Megavoltage CT scans were acquired daily as part of an image-guided registration protocol. Concurrent platinum-based systemic therapy was given to nine patients (64%).

RESULTS

HT resulted in durable local control in 21 of the 28 primary disease sites irradiated, including a complete clinical and radiographic response initially observed at 17 of the 20 sites with gross tumour. The mean displacements to account for interfraction motion were 2.44 ± 1.25, 2.92 ± 1.09 and 2.31 ± 1.70 mm for the medial-lateral (ML), superior-inferior (SI) and anteroposterior (AP) directions, respectively. Table shifts of >3 mm occurred in 19%, 20% and 22% of the ML, SI and AP directions, respectively. The 2-year estimates of overall survival, local-regional control and progression-free survival were 58%, 73% and 60%, respectively.

CONCLUSION

The effectiveness of HT for the treatment of synchronous primary cancers of the head and neck was demonstrated.

ADVANCES IN KNOWLEDGE

HT is a feasible option for synchronous primary cancers of the head and neck and can result in long-term disease control with acceptable toxicity in appropriately selected patients.

A novel mutation in the P2Y12 receptor and a function-reducing polymorphism in protease-activated receptor 1 in a patient with chronic bleeding

BACKGROUND

The study of patients with bleeding problems is a powerful approach in determining the function and regulation of important proteins in human platelets. We have identified a patient with a chronic bleeding disorder expressing a homozygous P2RY(12) mutation, predicting an arginine to cysteine (R122C) substitution in the G-protein-coupled P2Y(12) receptor. This mutation is found within the DRY motif, which is a highly conserved region in G-protein-coupled receptors (GPCRs) that is speculated to play a critical role in regulating receptor conformational states.

OBJECTIVES

To determine the functional consequences of the R122C substitution for P2Y(12) function.

PATIENT/METHODS

We performed a detailed phenotypic analysis of an index case and affected family members. An analysis of the variant R122C P2Y(12) stably expressed in cells was also performed.

RESULTS

ADP-stimulated platelet aggregation was reduced as a result of a significant impairment of P2Y(12) activity in the patient and family members. Cell surface R122C P2Y(12) expression was reduced both in cell lines and in platelets; in cell lines, this was as a consequence of agonist-independent internalization followed by subsequent receptor trafficking to lysosomes. Strikingly, members of this family also showed reduced thrombin-induced platelet activation, owing to an intronic polymorphism in the F2R gene, which encodes protease-activated receptor 1 (PAR-1), that has been shown to be associated with reduced PAR-1 receptor activity.

CONCLUSIONS

Our study is the first to demonstrate a patient with deficits in two stimulatory GPCR pathways that regulate platelet activity, further indicating that bleeding disorders constitute a complex trait.

Clinical-dosimetric relationship between lacrimal gland dose and ocular toxicity after intensity-modulated radiotherapy for sinonasal tumours

OBJECTIVE

To characterise the relationship between lacrimal gland dose and ocular toxicity among patients treated by intensity-modulated radiotherapy (IMRT) for sinonasal tumours.

METHODS

40 patients with cancers involving the nasal cavity and paranasal sinuses were treated with IMRT to a median dose of 66.0 Gy. Toxicity was scored using the Radiation Therapy Oncology Group morbidity criteria based on conjunctivitis, corneal ulceration and keratitis. The paired lacrimal glands were contoured as organs at risk, and the mean dose, maximum dose, V10, V20 and V30 were determined. Statistical analysis was performed using logistic regression and the Akaike information criterion (AIC).

RESULTS

The maximum and mean dose to the ipsilateral lacrimal gland were 19.2 Gy (range, 1.4-75.4 Gy) and 14.5 Gy (range, 11.1-67.8 Gy), respectively. The mean V10, V20 and V30 values were 50%, 25% and 17%, respectively. The incidence of acute and late Grade 3+ toxicities was 23% and 19%, respectively. Based on logistic regression and AIC, the maximum dose to the ipsilateral lacrimal gland was identified as a more significant predictor of acute toxicity (AIC, 53.89) and late toxicity (AIC, 32.94) than the mean dose (AIC, 56.13 and 33.83, respectively). The V20 was identified as the most significant predictor of late toxicity (AIC, 26.81).

CONCLUSION

A dose-response relationship between maximum dose to the lacrimal gland and ocular toxicity was established. Our data suggesting a threshold relationship may be useful in establishing dosimetric guidelines for IMRT planning that may decrease the risk of acute and late lacrimal toxicities in the future.

ADVANCES IN KNOWLEDGE

A threshold relationship between radiation dose to the lacrimal gland and ocular toxicity was demonstrated, which may aid in treatment planning and reducing the morbidity of radiotherapy for sinonasal tumours.

Esophageal tolerance to high-dose stereotactic ablative radiotherapy

Dose-volume parameters are needed to guide the safe administration of stereotactic ablative radiotherapy (SABR). We report on esophageal tolerance to high-dose hypofractionated radiation in patients treated with SABR. Thirty-one patients with spine or lung tumors received single- or multiple-fraction SABR to targets less than 1 cm from the esophagus. End points evaluated include D(5cc) (minimum dose in Gy to 5 cm(3) of the esophagus receiving the highest dose), D(2cc) , D(1cc) , and D(max) (maximum dose to 0.01 cm(3) ). Multiple-fraction treatments were correlated using the linear quadratic and linear quadratic-linear/universal survival models. Three esophageal toxicity events occurred, including esophagitis (grade 2), tracheoesophageal fistula (grade 4-5), and esophageal perforation (grade 4-5). Chemotherapy was a cofactor in the high-grade events. The median time to development of esophageal toxicity was 4.1 months (range 0.6-6.1 months). Two of the three events occurred below a published D(5cc) threshold, all three were below a D(2cc) threshold, and one was below a D(max) threshold. We report a dosimetric analysis of incidental dose to the esophagus from SABR. High-dose hypofractionated radiotherapy led to a number of high-grade esophageal adverse events, suggesting that conservative parameters to protect the esophagus are necessary when SABR is used, especially in the setting of chemotherapy or prior radiotherapy.

Evaluation of patterns of failure and subjective salivary function in patients treated with intensity modulated radiotherapy for head and neck squamous cell carcinomas

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Background: Conventional RT (CRT) for head and neck squamous cell carcinoma (HNSCC) is associated with severe late side effects which can worsen quality of life of surviving patients. Intensity-modulated radiotherapy (IMRT) allows the delivery of tumoricidal doses to the target volume while maintaining tolerable doses to critical organs. Several previous studies have demonstrated promising results for tumor control and disease free survival for HNSCC treated with IMRT. In this study, we correlated patterns of failure with target volume delineations in HNSCC treated with IMRT at our instittuion and evaluated subjective xerostomia outcomes after IMRT as compared to CRT. Material and Methods: Between 1/00 and 4/05, 69 patients with newly diagnosed non-metastatic HNSCC underwent curative parotid sparing IMRT at Stanford University. Sites included were oropharynx (39), oral cavity (8), larynx (8), hypopharynx (8) and unknown primary (6). Forty-six patients received definitive IMRT (66 Gy, 2.2 Gy/fraction), and 23 patients received post-operative IMRT (60.2 Gy, 2.15 Gy/fraction). Fifty-one patients also received concomitant chemotherapy. Post-treatment salivary gland function was evaluated by a validated xerostomia questionnaire (XQ) in 29 IMRT and 75 matched non-IMRT patients > 6 months after completing RT. Results: At a median follow-up of 17 months for living patients (range 6.5–60), 7 locoregional failures were observed, 5 in the gross target volume (GTV), 1 in the clinical target volume (CTV), and 1 at the junction of the IMRT and supraclavicular fields. The 2-year Kaplan Meier estimates of locoregional control and overall survival were 92% and 80% for definitive IMRT and 85% and 85% for post-op IMRT patients, respectively. The mean total XQ score was significantly better for IMRT than for non-IMRT patients (p = 0.006). Conclusions: The predominant pattern of failure in IMRT treated patients is in the GTV. Parotid sparing with IMRT resulted in decreased subjective xerostomia and may improve quality of life in irradiated HNSCC patients.

No significant financial relationships to disclose.

Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes--a randomized controlled trial

OBJECTIVE

This study sought to examine the effects of a 3-month programme of dietary advice to restrict carbohydrate intake compared with reduced-portion, low-fat advice in obese subjects with poorly controlled Type 2 diabetes.

RESEARCH DESIGN AND METHODS

One hundred and two patients with Type 2 diabetes were recruited across three centres and randomly allocated to receive group education and individual dietary advice. Weight, glycaemic control, lipids and blood pressure were assessed at baseline and 3 months. Dietary quality was assessed at the end of study.

RESULTS

Weight loss was greater in the low-carbohydrate (LC) group (-3.55 +/- 0.63, mean +/- sem) vs. -0.92 +/- 0.40 kg, P = 0.001) and cholesterol : high-density lipoprotein (HDL) ratio improved (-0.48 +/- 0.11 vs. -0.10 +/- 0.10, P = 0.01). However, relative saturated fat intake was greater (13.9 +/- 0.71 vs. 11.0 +/- 0.47% of dietary intake, P < 0.001), although absolute intakes were moderate.

CONCLUSIONS

Carbohydrate restriction was an effective method of achieving short-term weight loss compared with standard advice, but this was at the expense of an increase in relative saturated fat intake.

The -1185 A/G and -1051 G/A dimorphisms in the von Willebrand factor gene promoter and risk of myocardial infarction

Elevated plasma von Willebrand factor (VWF) levels are associated with coronary artery disease, although the precise mechanism for this is unclear. Recently, four linked dimorphisms in the VWF gene promoter were demonstrated to influence plasma VWF level. We conducted a case-control study of 525 acute myocardial infarction (MI) cases and 451 control subjects, all aged < or = 75 years, to assess the potential contribution of two of these dimorphisms (-1185 G/A and -1051 A/G) to the risk of MI. The frequency of the -1185A/-1051G haplotype, associated with elevated VWF levels, was similar in the case and control groups, yielding a haplotypic odds ratio for MI of 0.93 (95% CI 0.77, 1.12, P = 0.43), and there was no significant association between the -1185A/-1051G haplotype and the risk of MI in any subgroup analysed. We therefore conclude that possession of the -1185A/-1051G haplotype does not confer an increased risk for MI.

Novel platelet membrane glycoprotein VI dimorphism is a risk factor for myocardial infarction

BACKGROUND

Glycoprotein (GP) VI plays a crucial role in platelet activation and aggregation. We investigated whether polymorphic variation at the GP VI locus confers an increased risk of myocardial infarction (MI).

METHODS AND RESULTS

Coding and 5' and 3' non-coding regions of the GP VI gene were analyzed by polymerase chain reaction and conformation sensitive gel electrophoresis in 21 healthy subjects. Ten dimorphisms, 5 of which predicted amino acid substitutions (T13254C, A19871G, A21908G, A22630T, C22644A), were identified. Two core haplotypes involving 7 dimorphisms (C10781A and G10873A and all those predicting amino acid substitutions) were apparent. The contribution of the T13254C dimorphism, which predicted the substitution of serine 219 by proline, to risk of MI was assessed in 525 patients with acute MI and 474 controls, all aged <75 years. The allelic odds ratio (OR) for MI associated with the 13254C allele was 1.16 (95% CI, 0.91 to 1.46; P=0.23). Compared with corresponding control subgroups, the 13254CC genotype was more common among cases who were female (OR, 4.52; 95% CI, 1.23 to 16.64; P=0.029), nonsmokers (OR, 2.50; 95% CI, 0.98 to 6.38; P=0.048), aged >/=60 years (OR, 6.48; 95% CI, 1.47 to 28.45; P=0.009) or carried the beta-fibrinogen -148T allele associated with increased fibrinogen levels (OR, 10.49; 95% CI, 1.32 to 83.42; P=0.02). In logistic regression analysis that took other cardiovascular risk factors into account, the interactions of GP VI genotype with age (P=0.005) and beta-fibrinogen genotype (P=0.035) remained significant.

CONCLUSIONS

The GP VI 13254CC genotype increases the risk of MI, particularly in older individuals, and the interaction of the GP VI 13254C allele with other candidate risk alleles may accentuate this risk.

Endoplasmic reticulum retention and prolonged association of a von Willebrand's disease-causing von Willebrand factor variant with ERp57 and calnexin

We have previously identified a mutation (R273W) in the von Willebrand factor (VWF) propeptide that results in quantitative deficiency of plasma VWF and a loss of high molecular weight VWF multimers. Recombinant VWF having the R273W mutation (rVWFR273W) expressed in COS-7 cells demonstrated severely impaired secretion and degradation in an intracellular location [Allen, S., et al. (2000) Blood 96, 560-568]. In this report we used pulse-chase analysis and endoglycosidase H digestion of wild-type rVWF and rVWFR273W immunoprecipitated from COS-7 cells to show that rVWFR273W was retained in the endoplasmic reticulum (ER). We demonstrate for the first time that wild-type rVWF and rVWFR273W interacted with the thiol-dependent oxidoreductase ERp57 during biosynthesis in the ER. Pulse chase analysis demonstrated that the interactions of rVWFR273W with ERp57 and calnexin were prolonged compared to wild-type rVWF. In contrast there was no apparent difference between rVWFR273W and wild-type rVWF in their time-courses of interaction with calreticulin.

A novel von Willebrand disease-causing mutation (Arg273Trp) in the von Willebrand factor propeptide that results in defective multimerization and secretion

In this report we describe the molecular defect underlying partial and severe quantitative von Willebrand factor (VWF) deficiencies in 3 families previously diagnosed with types 1 and 3 Von Willebrand-disease. Analysis of the VWF gene in affected family members revealed a novel C to T transition at nucleotide 1067 of the VWF complemetary DNA (cDNA), predicting substitution of arginine by tryptophan at amino acid position 273 (R273W) of pre-pro-VWF. Two patients, homozygous for the R273W mutation, had a partial VWF deficiency (VWF:Ag levels of 0.06 IU/mL and 0.09 IU/mL) and lacked high-molecular weight VWF multimers in plasma. A third patient, also homozygous for the R273W mutation, had a severe VWF deficiency (VWF:Ag level of less than 0.01 IU/mL) and undetectable VWF multimers in plasma. Recombinant VWF having the R273W mutation was expressed in COS-7 cells. Pulse-chase experiments showed that secretion of rVWFR273W was severely impaired compared with wild-type rVWF. However, the mutation did not affect the ability of VWF to form dimers in the endoplasmic reticulum (ER). Multimer analysis showed that rVWFR273W failed to form high-molecular-weight multimers present in wild-type rVWF. We concluded that the R273W mutation is responsible for the quantitative VWF deficiencies and aberrant multimer patterns observed in the affected family members. To identify factors that may function in the intracellular retention of rVWFR273W, we investigated the interactions of VWF expressed in COS-7 cells with molecular chaperones of the ER. The R273W mutation did not affect the ability of VWF to bind to BiP, Grp94, ERp72, calnexin, and calreticulin in COS-7 cells. (Blood. 2000;96:560-568)

Influence of the -675 4G/5G dimorphism of the plasminogen activator inhibitor 1 promoter on thrombotic risk in patients with factor V Leiden

Elevated plasminogen activator inhibitor 1 (PAI-1) levels are associated with venous thromboembolism, although their significance is unclear. PAI-1 levels are influenced by a PAI-1 promoter dimorphism (4G/5G), the 4G allele being associated with increased PAI-1 activity. We investigated whether the 4G allele influenced thrombotic risk by studying 99 symptomatic factor V (FV) Leiden heterozygotes and 99 healthy subjects. The 4G allele was more prevalent among cases than among healthy subjects (chi2 = 8.00, P = 0.005) and the odds ratio (OR) for thrombosis associated with either heterozygosity or homozygosity for the 4G allele was 2.43 (P = 0. 011). We conclude that carriership of the 4G allele was more prevalent in patients who already carried factor V Leiden than in control subjects without factor V Leiden.

Acute fuel selection in response to high-sucrose and high-starch meals in healthy men

BACKGROUND

Despite considerable controversy over the inclusion of sucrose in the diets of people with diabetes, the acute metabolism of sucrose is not completely understood.

OBJECTIVE

Our objective was to investigate the metabolism of the monomeric constituents of sucrose after a high-sucrose meal.

DESIGN

Three test meals were consumed in a randomized, crossover design by 7 healthy male volunteers. Two of the meals were high in sucrose; one was supplemented with 200 mg uniformly labeled [13C]fructose and one was supplemented with 200 mg [13C]glucose. The other meal was high in starch, supplemented with 200 mg [13C]glucose. Fifty percent of energy was supplied as sucrose in the high-sucrose meals and as starch in the high-starch meal. Breath (13)CO(2) enrichment was measured at 15-min intervals and indirect calorimetry was performed for five 20-min sessions immediately before and during a 6-h postprandial period.

RESULTS

Carbohydrate oxidation rates rose much faster after the high-sucrose meals than after the high-starch meal. Breath (13)CO(2) enrichment rose faster and peaked earlier and at a higher value when [13C]fructose rather than [13C]glucose was given with the high-sucrose test meal. Values for breath (13)CO(2) enrichment from [13C]glucose after the high-starch meal were intermediate.

CONCLUSIONS

These results show that fructose is preferentially oxidized compared with glucose after a high-sucrose meal and that glucose is oxidized more slowly after a high-sucrose meal than after a high-starch meal.

Major structural defects in the antithrombin gene in four families with type I antithrombin deficiency--partial/complete deletions and rearrangement of the antithrombin gene

The molecular basis of quantitative antithrombin deficiency was investigated in four families predicted to have major antithrombin gene rearrangements. A 1,442 bp deletion and insertion of the sequence 5'T(n = 38-40)GAGACG was characterised in one case. Sequence surrounding the breakpoints contained two perfect, and one imperfect, inverted repeats which may have mediated formation of a stem loop structure on one strand during DNA replication potentiating the deletion. A 9,219 bp deletion spanning introns 2 to 5 was identified in a second family. The identical 6 bp sequence was upstream of each breakpoint and the 5' breakpoint was located in a sequence of the Alu 3 repeat predicted to be susceptible to strand breakage during transcription. This may have promoted misalignment, and deletion, of one of the repeats and the intervening DNA. A novel 1.8 kb antithrombin gene fragment was present in DNA digests from affected members of the third family suggesting a partial antithrombin gene duplication event while in the remaining family, evidence supporting a complete gene deletion was obtained.

Genetic analysis, phenotypic diagnosis, and risk of venous thrombosis in families with inherited deficiencies of protein S

Protein S deficiency is a recognized risk factor for venous thrombosis. Of all the inherited thrombophilic conditions, it remains the most difficult to diagnose because of phenotypic variability, which can lead to inconclusive results. We have overcome this problem by studying a cohort of patients from a single center where the diagnosis was confirmed at the genetic level. Twenty-eight index patients with protein S deficiency and a PROS1 gene defect were studied, together with 109 first-degree relatives. To avoid selection bias, we confined analysis of total and free protein S levels and thrombotic risk to the patients' relatives. In this group of relatives, a low free protein S level was the most reliable predictor of a PROS1 gene defect (sensitivity 97.7%, specificity 100%). First-degree relatives with a PROS1 gene defect had a 5.0-fold higher risk of thrombosis (95% confidence interval, 1. 5-16.8) than those with a normal PROS1 gene and no other recognized thrombophilic defect. Although pregnancy/puerperium and immobility/trauma were important precipitating factors for thrombosis, almost half of the events were spontaneous. Relatives with splice-site or major structural defects in the PROS1 gene were more likely to have had a thrombotic event and had significantly lower total and free protein S levels than those relatives having missense mutations. We conclude that persons with PROS1 gene defects and protein S deficiency are at increased risk of thrombosis and that free protein S estimation offers the most reliable way of diagnosing the deficiency. (Blood. 2000;95:1935-1941)

Two novel type 2N von Willebrand disease-causing mutations that result in defective factor VIII binding, multimerization, and secretion of von Willebrand factor

Two novel mutations, a T-to-C transition at nucleotide 2612 and a T-to-G transversion at nucleotide 3923 of the von Willebrand factor (vWF) complementary DNA, were detected by analysis of the vWF gene in DNA from members of 2 families with atypical von Willebrand disease. The T2612C transition predicts substitution of cysteine by arginine at amino acid position 788 (C788R), and the T3923G transversion predicts substitution of cysteine by glycine at position 1225 (C1225G) of pre-pro-vWF. The patients homozygous for the C788R and C1225G mutations both had a partial vWF deficiency (0. 18 IU/mL and 0.07 IU/mL vWF antigen, respectively); vWF in plasma from patients homozygous for either the C788R or the C1225G mutation failed to bind factor VIII and lacked high molecular weight multimers. Recombinant (r) vWF molecules having the C788R or C1225G mutation were expressed in COS-7 cells. Both rvWF C788R and rvWF C1225G exhibited significantly impaired secretion and failed to bind factor VIII. Recombinant vWF C788R in COS-7 culture medium showed a severe reduction in high molecular weight multimers, whereas rvWF C1225G showed a very mild reduction in high molecular weight multimers when compared with wild-type rvWF. (Blood. 2000;95:2000-2007)

The GPIa C807T dimorphism associated with platelet collagen receptor density is not a risk factor for myocardial infarction

The platelet collagen receptor, GPIa/IIa, is an important mediator of platelet adhesion to fibrillar collagens at sites of vascular injury. Recently, a dimorphism at nucleotide 807 of the GPIa cDNA (TTC/TTT in codon 224) was shown to be associated with variation in GPIa/IIa receptor density on the platelet surface. We conducted a case-control study to determine if the 807T allele, linked with increased GPIa/IIa density, contributed to risk of myocardial infarction (MI). DNA from 546 acute MI cases and 507 controls, all aged <75 years, was genotyped for the C807T dimorphism using the TaqManTM system of allelic discrimination. The allelic odds ratio (OR) for MI in the complete cohort was 0.88 (95% CI 0.74-1.05, P = 0.17), indicating that the 807T allele was not associated with an increased risk of MI. There was also no increased risk of MI associated with the homozygous 807TT (P = 0.22) or heterozygous 807CT (P = 0.24) genotypes or for carriers of the 807T allele in any cohort subgroup analysed. We conclude that the GPIa 807T allele is not a risk factor for MI in our population either alone or in combination with other major cardiovascular risk factors.

The prothrombin 20210A allele and its association with myocardial infarction

The relationship between the prothrombin (PT) 20210A allele and arterial disease is controversial. We conducted a case-control study to assess its contribution to risk of myocardial infarction (MI). Five hundred and thirty-nine acute MI patients and 498 control subjects aged <75 years were studied. Two percent of cases carried the PT20210A allele compared to 2.8% of controls. The odds ratio for MI was 0.72 (95% CI 0.32-1.60) indicating that the PT20210A allele confers no increased risk for MI. Subgroup analysis showed no association between the PT20210A allele and either premature MI or MI in females. We conclude the PT20210A allele is not a risk factor for MI and suggest that discrepancies in studies relating the PT20210A allele to MI may be due to difficulties in estimating its low allelic frequency in the general population and thus random differences in the observed frequencies in the control populations studied.

Dietary carbohydrates and insulin sensitivity

This review considers recent findings and ideas on the impact of dietary carbohydrates on insulin sensitivity in the context of the prevention of diabetes and cardiovascular disease. We assess the evidence for benefits in insulin sensitivity following high starch as distinct from high sucrose intakes when the diet is low in fat. We consider relationships between obesity, leptin and carbohydrate intake. We conclude that reducing the rate of carbohydrate digestion in the small bowel may be the key stage at which to intervene to reduce insulinaemia and so prevent downregulation of insulin receptors and insulin resistance.

A novel mutation in intron K of the PROS1 gene causes aberrant RNA splicing and is a common cause of protein S deficiency in a UK thrombophilia cohort

In the course of investigating the molecular basis of protein S deficiency in 31 index cases with thrombophilia, we identified seven kindred where the underlying defect was a novel A to G transition 9 bp upstream of exon 12 in intron K of the PROS1 gene. In all but one case, the mutation caused type I deficiency. One individual had type III deficiency. While ectopic transcript analysis using the BstXI dimorphism in exon 15 failed to detect a transcript from the mutated allele, analysis of transcripts spanning exons 11 and 12 revealed a minor mRNA species. Sequencing confirmed the mutation created a new RNA acceptor site introducing 8 nucleotides of intronic sequence into the mature mRNA. Haplotype analysis of the defective PROS1 alleles in six families revealed the same haplotype in all affected individuals suggesting the presence of a common ancestor. Six of the fourteen relatives with the mutation experienced at least one venous thrombotic event strongly supporting the association of the mutation with venous thrombosis.

Acute effects on insulin sensitivity and diurnal metabolic profiles of a high-sucrose compared with a high-starch diet

Decreased insulin sensitivity is associated with diabetes mellitus, ischemic heart disease, and hypertension, both independently and in association as what is called the metabolic syndrome. Although the negative effects of obesity, sedentary lifestyles, and high-fat diets on insulin sensitivity are well established, the influence of type and quantity of dietary carbohydrate is more controversial. This study aimed to assess the acute (24 h) effects of a high-sucrose compared with a high-starch diet on insulin sensitivity and to identify changes in blood metabolites that might lead to altered insulin sensitivity. Eight healthy adults consumed high-sucrose or high-starch diets (50% of dietary energy) in a randomized, crossover trial. Insulin sensitivity was assessed by a short insulin tolerance test the following morning. No differences were detected in insulin sensitivity, either for glucose metabolism [Kitt(glucose) (the rate constant for the decline in blood glucose concentrations) for sucrose diet = 3.86%/min, for starch diet = 3.72%/min; pooled SEM = 0.23] or for lipid metabolism [Kitt(NEFA) (the rate constant for the decline in blood fatty acid concentrations) for sucrose diet = 12.9%/min, for starch diet = 11.4%/min; pooled SEM = 1.18]. Profiles for blood glucose and serum insulin concentrations revealed higher peaks and lower troughs with the high-sucrose diet whereas area under the curve for glucose was higher with the high-starch diet (6780 +/- 245 mmol x L/min) than with the high-sucrose diet (6290 +/- 283 mmol x L/min) (P < 0.001). Plasma fatty acid concentrations showed a late postprandial rise with the sucrose-rich diet relative to the starch-rich diet, which was mirrored with a fractionally later peak in triacylglycerol concentrations.

Antithrombin cambridge II (Ala384Ser): clinical, functional and haplotype analysis of 18 families

Thirty-one individuals from 18 unrelated families with antithrombin deficiency have been identified as having a single point mutation within codon 384 (13268 GCA-->TCA) resulting in an alanine to serine substitution. Six families (11 individuals) were identified by the screening of individuals with thromboembolic disease or with a family history of thromboembolic disease, whilst the remaining 12 families (20 individuals) were identified by screening of asymptomatic blood donors. Four individuals had a history of venous thrombotic disease, a further 2 gave a history of superficial thrombophlebitis but the remaining 25 individuals were asymptomatic. Affected individuals demonstrated normal immunological levels of antithrombin but a decrease in anti-IIa activity in the presence of heparin. Haplotype analysis was used to examine the possibility of a founder effect to explain the high frequency of this non-CpG mutation. 29/31 individuals showed a single common "core" haplotype, the only variation existing in the number of copies of an (ATT)n repeat polymorphism--13, 14, 15 or 17. The results suggest that at most there are four independent origins for this mutation.

Co-inheritance of the 20210A allele of the prothrombin gene increases the risk of thrombosis in subjects with familial thrombophilia

The presence of the 20210A allele of the prothrombin (PT) gene has recently been shown to be a risk factor for venous thromboembolism. This is probably mediated through increased plasma prothrombin levels. The aim of this study was to compare the prevalence of the prothrombin 20210A allele in control subjects and in subjects with recognised thrombophilia and to establish whether the additional inheritance of the PT 20210A allele is associated with an increased risk of venous thromboembolism. 101 subjects with a history of venous thromboembolism and diagnosed as having either factor V Leiden (R506Q) or heritable deficiencies of protein C, protein S or antithrombin were studied. The prevalence of the PT 20210A allele in this group was compared with the results obtained for 150 control subjects. In addition, the relationships were examined between genetic status and the number of documented thromboembolic episodes, and between plasma prothrombin levels and possession of the PT 20210A allele. 8 (7.9%) of the 101 patients were also heterozygous for the PT 20210A allele. This compares with 0.7% in the control subjects (p = 0.005). After exclusion of patients on warfarin, the mean plasma prothrombin of 113 subjects without 20210A was 1.09 U/ml, as compared with 1.32 U/ml in 8 with the allele (p = 0.0002). Among the 101 patients with either factor V Leiden, protein S deficiency, protein C deficiency or antithrombin deficiency, the age adjusted mean (SD) number of venous thromboembolic episodes at diagnosis was 3.7 (1.5) in those with the PT 20210A allele, as compared with 1.9 (1.1) in those without (p = 0.0001). We have demonstrated that the prevalence of the PT 20210A allele is significantly greater in subjects with venous thrombosis and characterised heritable thrombophilia than in normal control subjects and that the additional inheritance of PT 20210A is associated with an increased risk of venous thromboembolism. We have also confirmed that plasma prothrombin levels are significantly greater in subjects possessing the PT 20210A compared with those who do not.

Dietary carbohydrates and insulin sensitivity: a review of the evidence and clinical implications

Insulin resistance is associated with diabetes mellitus, ischemic heart disease, and hypertension both independently and as part of syndrome X. Environmental influences on SI are incompletely understood. Exercise has a strong beneficial effect and obesity a strong adverse effect. The balance of evidence suggests that a high-fat diet is likely to reduce insulin sensitivity but the effects of dietary carbohydrates are more controversial. Extensive studies in animals showed a detrimental effect of diets very high in fructose or sucrose, particularly in association with induction of hypertriglyceridemia. The more limited studies in humans had conflicting results, partly because of heterogeneity of design. Certain groups of subjects may be more sensitive to adverse effects of high intakes of dietary sucrose or fructose. More carefully controlled studies in humans are needed to provide evidence on which to base public health policies with respect to dietary carbohydrates and SI.

Molecular basis of protein S deficiency in three families also showing independent inheritance of factor V leiden

The molecular basis of type I or III Protein S deficiency has been investigated in three kindred also showing independent inheritance of factor V (FV) Leiden. A T to C transition in codon 570 (Met-->Thr) was identified in the propositi and shown to segregate with protein S deficiency in all but one of the affected members of two kindred. This individual was heterozygous for a second transition (C to T) causing substitution of serine 624 by leucine. A second member of the same family, with markedly reduced free protein S levels when compared with affected relatives, was heterozygous for both mutations. Haplotype analysis of individuals with the mutated ATG570ACG allele in the two kindred suggested they may have been related by a common ancestor. A G to A transition resulting in substitution of cysteine 145 by tyrosine was detected in the third kindred. All mutations are believed to interfere with protein S binding to C4b-binding protein resulting in reduced free protein S levels. Of the five individuals studied who had experienced thrombotic events, three had combined protein S deficiency and FV Leiden reemphasising the importance of FV Leiden as an additional risk factor for thrombosis in protein S deficiency.

Two antithrombin mutations in a compound heterozygote: Met20Thr and Tyr166Cys

The molecular basis for a family with Type I antithrombin deficiency has been established. Amplification and sequencing of the antithrombin gene identified two mutations: Met20Thr (2523T-->C) within exon 2 and Tyr166Cys (5493A-->G) within exon 3a. Further analysis indicated that the propositus was a compound heterozygote but in addition provided evidence for phase disruption during the amplification and/or cloning procedure. The Met20Thr mutation appears to be a neutral mutation with no functional consequences. In contrast, the Tyr166Cys mutation is associated with a Type I phenotype.

Two novel antithrombin variants, Asn187Asp and Asn187Lys, indicate a functional role for asparagine 187

Three unrelated families have been identified with mutations involving asparagine 187. Two of these families are asymptomatic and were identified during the screening of random blood donors, whilst the third has a history of recurrent thromboembolic disease. In two families the mutation (6460 AAC-->GAC) results in an asparagine to aspartate substitution and is associated with normal immunological levels of antithrombin but a reduction in functional activity. In the third family the mutation (6462 AAC-->AAA) results in an asparagine to lysine substitution at residue 187 and is associated with a parallel reduction in both immunological and functional antithrombin levels. Asparagine 187 is located in the middle of the F helix of antithrombin and forms the major link between the F helix and strand 3 of the A sheet. The F helix is seen to overlie the A sheet of the molecule and moves with strands 2 and 3 of this sheet as they open to allow entry of the reactive site loop to form strand 4. Substitutions of asparagine 187 are, therefore, likely to disrupt this sliding movement leading to a loss of inhibitory activity.

High prevalence of a mutation in the factor V gene within the U.K. population: relationship to activated protein C resistance and familial thrombosis

Recent findings have indicated the importance of factor V (FV) in causing resistance to activated protein C (APC) in a high proportion of patients with venous thrombosis. This prompted us to investigate whether resistance could be due to defective inactivation of FVa by APC. Consequently, we amplified a 3.2 kb fragment of the FV gene sequence encoding the heavy chain APC cleavage site. DNA analysis showed a guanine to adenine transition at nucleotide 1691 in all affected members of two families with inherited APC resistance associated with thrombosis and confirmed suspected homozygosity in two individuals. The mutation, in heterozygous form, was also found in approximately 3.5% of our normal population (n = 144) and correlated with low APC resistance. The high prevalence of this mutation suggests that it may be a major contributory factor in early thrombosis.

Prevalence of antithrombin deficiency in the healthy population

In a cohort of 9669 blood donors we have identified 16 cases of congenital AT deficiency (1 in 600) by way of family studies and AT gene analysis. Two donors had type I AT deficiency (prevalence 0.21 per 1000; 95% CI = 0.03/1000 to 0.75/1000), their families displaying a symptomatic phenotype. 14 donors had a type II deficiency (prevalence 1.45 per 1000; 95% CI = 0.79/1000 to 2.43/1000): one recurring and three unique mutations. None of these type II deficiencies appeared to confer a high thrombotic risk despite many of the affected individuals having experienced potentially prothrombotic challenges. The high frequency of these relatively asymptomatic variants may reflect a selection bias in the study population. However, their existence should not only add to our understanding of structure-function relationships of AT but may also influence our management of asymptomatic deficient individuals identified in epidemiological or presurgical screening programmes.

DdeI polymorphism in intron 5 of the ATIII gene

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Towards a phenomenology of caregiving: growth in the caregiver is a vital component

The classical notions of 'virtue' and 'leisure' offer excellent insights into the essentially moral nature of medical practice. This is especially evident in the understanding that professional caregiving has the potential to enhance the moral character as well as the moral awareness of the practitioner. Reflective awareness of the moral nature of the caregiving process can also contribute to coping with negative stress, which almost always has its origins in frustrations rooted in moral quandaries and evaluations. Understanding the process required arises from implementation of caregiving in combination with deliberate, conscious development of spiritual awareness and reflection on moral meaning.

Specificity analysis of human monoclonal antibodies reactive with cell surface and intracellular antigens

Over 4350 human Ig-secreting hybrids have been generated through the fusion of human lymphocytes with NS-1 (mouse), LICR-2, SKO-007, GM4672, or UC729-6 (human) myeloma and lymphoblastoid cell lines. NS-1 proved to be the most satisfactory fusion partner, and 83% of the stable Ig-secreting clones were derived from NS-1 fusions. Three hundred five hybrids produced human monoclonal antibodies (hmAb) reactive with cell surface or intracellular antigens expressed by cultured human tumor cell lines, and 111 of these have undergone detailed serological specificity analysis. Several general points have emerged from our study of hmAb: A significant proportion of the human B-cell clones produce antibody reactive with cellular antigens. The majority of these antigens have an intracellular location and are broadly distributed. Intracellular and cell surface differentiation antigens and other antigens with restricted distribution have been defined by hmAb, including two cell surface antigens not detected on normal cells. The relationship of these findings to cancer is unclear, as hmAb reactive with antigens showing distinctive distribution have been generated from the lymphocytes of normal individuals as well as tumor-bearing patients.