Search tips
Search criteria

Results 1-10 (10)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  Dosimetric and radiobiological comparison of helical tomotherapy, forward-planned intensity-modulated radiotherapy and two-phase conformal plans for radical radiotherapy treatment of head and neck squamous cell carcinomas 
The British Journal of Radiology  2011;84(1008):1083-1090.
The usual radical radiotherapy treatment prescribed for head and neck squamous cell carcinoma (HNSCC) is 70 Gy (in 2 Gy per fraction equivalent) administered to the high-risk target volume (TV). This can be planned using either a forward-planned photon-electron junction technique (2P) or a single-phase (1P) forward-planned technique developed in-house. Alternatively, intensity-modulated radiotherapy (IMRT) techniques, including helical tomotherapy (HT), allow image-guided inversely planned treatments. This study was designed to compare these three planning techniques with regards to TV coverage and the dose received by organs at risk.
We compared the dose–volume histograms and conformity indices (CI) of the three planning processes in five patients with HNSCC. The tumour control probability (TCP), normal tissue complication probability (NTCP) and uncomplicated tumour control probability (UCP) were calculated for each of the 15 plans. In addition, we explored the radiobiological rationality of a dose-escalation strategy.
The CI for the high-risk clinical TV (CTV1) in the 5 patients were 0.78, 0.76, 0.82, 0.72 and 0.81 when HT was used; 0.58, 0.56, 0.47, 0.35 and 0.60 for the single-phase forward-planned technique and 0.46, 0.36, 0.29, 0.22 and 0.49 for the two-phase technique. The TCP for CTV1 with HT were 79.2%, 85.2%, 81.1%, 83.0% and 53.0%; for single-phase forward-planned technique, 76.5%, 86.9%, 73.4%, 81.8% and 31.8% and for the two-phase technique, 38.2%, 86.2%, 42.7%, 0.0% and 3.4%. Dose escalation using HT confirmed the radiobiological advantage in terms of TCP.
TCP for the single-phase plans was comparable to that of HT plans, whereas that for the two-phase technique was lower. Centres that cannot provide IMRT for the radical treatment of all patients could implement the single-phase technique as standard to attain comparable TCP. However, IMRT produced better UCP, thereby enabling the exploration of dose escalation.
PMCID: PMC3473826  PMID: 22101580
2.  Clinical challenges in the implementation of a tomotherapy service for head and neck cancer patients in a regional UK radiotherapy centre 
The British Journal of Radiology  2011;84(1000):358-366.
Intensity-modulated radiotherapy (IMRT) is increasingly being used to treat head and neck cancer cases.
We discuss the clinical challenges associated with the setting up of an image guided intensity modulated radiotherapy service for a subset of head and neck cancer patients, using a recently commissioned helical tomotherapy (HT) Hi Art (Tomotherapy Inc, WI) machine in this article. We also discuss the clinical aspects of the tomotherapy planning process, treatment and image guidance experiences for the first 10 head and neck cancer cases. The concepts of geographical miss along with tomotherapy-specific effects, including that of field width and megavoltage CT (MVCT) imaging strategy, have been highlighted using the first 10 head and neck cases treated.
There is a need for effective streamlining of all aspects of the service to ensure compliance with cancer waiting time targets. We discuss how patient toxicity audits are crucial to guide refinement of the newly set-up planning dose constraints.
This article highlights the important clinical issues one must consider when setting up a head and neck IMRT, image-guided radiotherapy service. It shares some of the clinical challenges we have faced during the setting up of a tomotherapy service. Implementation of a clinical tomotherapy service requires a multidisciplinary team approach and relies heavily on good team working and effective communication between different staff groups.
PMCID: PMC3473475  PMID: 21159810
5.  T-cell, adhesion, and B-cell epitopes of the cell surface Streptococcus mutans protein antigen I/II. 
Infection and Immunity  1995;63(9):3649-3658.
The T-cell and antibody responses to a cell surface streptococcal antigen (SA I/II) were investigated in naturally sensitized humans. Serum antibody responses were directed predominantly to the N-terminal (residues 39 to 481) and central (residues 816 to 1213) regions of SA I/II which may be involved in bacterial adhesion to salivary receptors. T-cell responses were also directed predominantly towards the central region. The linear peptide relationship of the immunodominant and minor T- and B-cell as well as adhesion epitopes was mapped within residues 816 to 1213. Immunodominant T-cell and B-cell epitopes were identified within residues 803 to 853, which were separated in linear sequence from the adhesion epitopes (residues 1005 to 1044). Adhesion epitopes overlapped with minor B- and T-cell epitopes (residues 1005 to 1054 and 1085 to 1134). An immunodominant promiscuous T-cell epitope (residues 985 to 1004) was adjacent to an adhesion epitope (residues 1005 to 1024). The limited B-cell response to adhesion epitopes is consistent with the success of Streptococcus mutans in colonizing the oral cavity. The strategy of T-cell, adhesion, and B-cell epitope mapping has revealed a general approach for identifying components of subunit vaccines which may focus responses to critical functional determinants. Such epitopes of SA I/II may constitute the components of a subunit vaccine against dental caries.
PMCID: PMC173506  PMID: 7642303
6.  Patient's charter in outpatient services. 
BMJ : British Medical Journal  1992;305(6846):186.
PMCID: PMC1883248  PMID: 1515857
7.  Treating bony metastases. 
BMJ : British Medical Journal  1991;303(6813):1335.
PMCID: PMC1671426  PMID: 1720990
8.  Conservation of the gene encoding streptococcal antigen I/II in oral streptococci. 
Infection and Immunity  1991;59(8):2686-2694.
The spaP gene of Streptococcus mutans serotype c encodes a major cell surface protein, streptococcal antigen (SA) I/II, with an Mr of 185,000, that is thought to be involved in bacterial adhesion to teeth. Proteins with significant amino acid sequence homology to SA I/II have also been found in S. sobrinus and S. sanguis. The objectives of this study were to investigate the conservation of the spaP gene in the mutans groups of streptococci and to determine whether homologous genes were present in other species of alpha-hemolytic streptococci. DNA extracted from representative strains of 19 streptococcal species was examined by Southern hybridization and partial DNA sequence analysis. A series of five overlapping DNA probes from the spaP gene were amplified by the polymerase chain reaction and used in the Southern hybridizations. The entire gene was found to be well conserved in all strains of S. mutans serotypes c, e, and f investigated. A probe from the 3' region of the gene, which encodes residues 857 to 1207 of the SA I/II protein, hybridized with DNA from a number of mutans streptococci, as well as with DNA from nonmutans alpha-hemolytic streptococci. Conservation within this region was further demonstrated by sequencing gene fragments of two strains of S. intermedius and S. oralis. The results show that some regions of the spaP gene are highly conserved not only in the mutans group of streptococci but also in other nonmutans alpha-hemolytic streptococci. This suggests that a family of cell surface proteins which, by analogy with the 185,000-Mr SA I/II of S. mutans, could be involved in bacterial adhesion might exist.
PMCID: PMC258074  PMID: 1855988
9.  A protein fragment of streptococcal cell surface antigen I/II which prevents adhesion of Streptococcus mutans. 
Infection and Immunity  1993;61(11):4590-4598.
Attachment of Streptococcus mutans to the tooth surface involves a cell surface protein with an M(r) of 185,000, termed streptococcal antigen (SA) I/II. Four overlapping fragments of the gene encoding SA I/II were amplified by polymerase chain reaction, cloned, and expressed in Escherichia coli. The recombinant polypeptides were assayed for adhesion-binding activity to salivary receptors and for recognition by a panel of monoclonal antibodies (MAbs) raised against SA I/II. Two of the MAbs which are known to prevent colonization of S. mutans in vivo bound the recombinant polypeptide comprising residues 816 to 1161. In vitro adhesion of S. mutans to saliva-coated hydroxyapatite beads was also inhibited specifically by a polypeptide (residues 816 to 1213) encompassing the same region. The evidence from the MAbs preventing colonization of S. mutans and the adherence inhibition assay suggests that an adhesion-binding activity resides within the portion of SA I/II comprising residues 816 to 1213, which is highly conserved among oral streptococcal species.
PMCID: PMC281209  PMID: 7691754
10.  Sequence and structural analysis of surface protein antigen I/II (SpaA) of Streptococcus sobrinus. 
Infection and Immunity  1991;59(8):2677-2685.
Streptococcal antigen I/II or the surface protein antigen A (SpaA) of Streptococcus sobrinus is an adhesin which mediates binding of the organism to tooth surfaces. The complete sequence of the gene which encodes SpaA has been determined. The gene consists of 4,584 bp and encodes a protein of 1,528 amino acid residues. The deduced amino acid sequence shows extensive homology with those of the cell surface adhesins from Streptococcus mutans serotypes c and f and from Streptococcus sanguis. Structural analysis of the N-terminal region (residues 50 to 550), which is rich in alanine and includes four tandem repeats of an 82-residue sequence, suggests that it adopts an alpha-helical coiled-coil conformation. Cell surface hydrophobicity may be associated with this region. The C-terminal region is more conserved and includes two tandem repeats of a 39-residue proline-rich sequence. A further proline-rich sequence in this region is predicted to span the cell wall. Although a hydrophobic sequence is present in the C-terminal region, it appears to be too short to span the cell membrane. Anchoring of SpaA in the cell membrane may therefore require some form of posttranslational modification or association with another membrane protein.
PMCID: PMC258073  PMID: 1855987

Results 1-10 (10)