Mechanistic validation of a clinical lead stapled peptide that reactivates p53 by dual HDM2 and HDMX targeting.

Hydrocarbon-stapled peptides that display key residues of the p53 transactivation domain have emerged as bona fide clinical candidates for reactivating the tumor suppression function of p53 in cancer by dual targeting of the negative regulators HDM2 and HDMX. A recent study questioned the mechanistic specificity of such stapled peptides based on interrogating their capacity to disrupt p53/HDM2 and p53/HDMX complexes in living cells using a new recombinase enhanced bimolecular luciferase complementation platform (ReBiL). Here, we directly evaluate the cellular uptake, intracellular targeting selectivity and p53-dependent cytotoxicity of the clinical prototype ATSP-7041. We find that under standard serum-containing tissue culture conditions, ATSP-7041 achieves intracellular access without membrane disruption, dose-dependently dissociates both p53/HDM2 and p53/HDMX complexes but not an unrelated protein complex in long-term ReBiL experiments, and is selectively cytotoxic to cancer cells bearing wild-type p53 by inducing a surge in p53 protein level. These studies underscore the importance of a thorough stepwise approach, including consideration of the time-dependence of cellular uptake and intracellular distribution, in evaluating and advancing stapled peptides for clinical translation.

An evaluation of four CT-MRI co-registration techniques for radiotherapy treatment planning of prone rectal cancer patients.

OBJECTIVES: MRI is the preferred staging modality for rectal carcinoma patients. This work assesses the CT-MRI co-registration accuracy of four commercial rigid-body techniques for external beam radiotherapy treatment planning for patients treated in the prone position without fiducial markers. METHODS: 17 patients with biopsy-proven rectal carcinoma were scanned with CT and MRI in the prone position without the use of fiducial markers. A reference co-registration was performed by consensus of a radiologist and two physicists. This was compared with two automated and two manual techniques on two separate treatment planning systems. Accuracy and reproducibility were analysed using a measure of target registration error (TRE) that was based on the average distance of the mis-registration between vertices of the clinically relevant gross tumour volume as delineated on the CT image. RESULTS: An automated technique achieved the greatest accuracy, with a TRE of 2.3 mm. Both automated techniques demonstrated perfect reproducibility and were significantly faster than their manual counterparts. There was a significant difference in TRE between registrations performed on the two planning systems, but there were no significant differences between the manual and automated techniques. CONCLUSION: For patients with rectal cancer, MRI acquired in the prone treatment position without fiducial markers can be accurately registered with planning CT. An automated registration technique offered a fast and accurate solution with associated uncertainties within acceptable treatment planning limits.

Comparison between margin-growing algorithms in radiotherapy software environments.

Margin-growing algorithms are commonly used tools that are available within virtual simulation and treatment planning software. We report on the accuracy of the margin-growing algorithms available in six commercially available radiotherapy software environments. A phantom containing two differently sized spheres and two rods (one level and one inclined) was constructed and scanned by CT with 1.25 mm, 2.5 mm, 3.75 mm and 5 mm slice thicknesses. The objects were outlined on a GE Advantage Simulator, and the outlined volumes recorded. Images and structures were transferred to MasterPlan, Xio, Pinnacle, Eclipse and Prosoma, where imported volumes were recorded. The contours on each system were grown isotropically by 10 mm, 20 mm and 30 mm, and volumes for each grown contour were recorded. Transfer of structure sets created in GE Advantage Simulator to the other software environments showed that the reported volumes of the four structures differ on each system. Results showed no correlation between volume accuracy and slice thickness. In general, margin growth of up to 30 mm for the rods and spheres is shown to be consistent between systems to within 1.33 mm for all slice thicknesses. Slice thickness did not appear to influence the accuracy of margin growth. Although this work highlights apparent differences in the reported volumes grown from the same original structure sets, the significance of this aspect of the planning process needs to weighed against reported intra- and inter-clinician variability in contour definition. It is not unreasonable, however, to expect that software packages should at least be consistent in volume information provided to the user.

The matching of wedge transmission factors across six multi-energy linear accelerators.

Elekta Precise linear accelerators create a wedged isodose distribution using a single, fixed, motorized wedge with a nominal wedge angle of 60 degrees. Wedge angles of less than 60 degrees can be produced by varying the proportion of open and wedge monitor units for a given exposure. The fixed wedge can be replaced with a mobile wedge, the position of which can be moved in order to adjust the wedge transmission factor (WTF). Using the original fixed wedges installed in our fleet of six Elekta accelerators, we found a range of 4% in measured wedge transmission factor for 6 MV beams. Results are presented which demonstrate that by using the mobile wedge it is possible to match the wedge transmission factors to within 1% for the six linear accelerators over three energies.

The effect of carbon fiber couch inserts on surface dose with beam size variation.

There is little evidence in the literature regarding the effects of a carbon fiber insert on beam parameters with beam size variations. We demonstrated this effect and noted the magnitude of the change of surface dose induced. It was shown that use of the carbon fiber insert panel, despite providing minimal attenuation of the primary radiation, significantly decreased the skin-sparing effect. The magnitude of this decrease was relatively larger for smaller beam sizes. The surface dose was nearly 4 times as large when carbon was added to a 10 x 10-cm beam, and nearly double for a 40 x 40-cm beam.

Evaluation of in vivo dose measurements for patients undergoing electron boost treatments.

This study evaluated p-type silicon diodes for use in in vivo dosimetry in clinical electron beams. A calibrated p-type silicon diode detector was used to measure the dose received by the patient in the centre of the field. Readings were corrected for energy, temperature and stand-off of the electron applicator from the patient surface. The mean difference between measured and prescribed dose was 1.04% (95% CI 0.72 to 1.36 %).

IPEM guidelines on dosimeter systems for use as transfer instruments between the UK primary dosimetry standards laboratory (NPL) and radiotherapy centres.

United Kingdom dosimetry codes of practice have traditionally specified one electrometer for use as a secondary standard, namely the Nuclear Enterprises (NE) 2560 NPL secondary standard therapy level exposure meter. The NE2560 will become obsolete in the foreseeable future. This report provides guidelines to assist physicists following the United Kingdom dosimetry codes of practice in the selection of an electrometer to replace the NE2560 when necessary. Using an internationally accepted standard (BS EN 60731:1997) as a basis, estimated error analyses demonstrate that the uncertainty (one standard deviation) in a charge measurement associated with the NE2560 alone is approximately 0.3% under specified conditions. Following a review of manufacturers' literature, it is considered that modern electrometers should be capable of equalling this performance. Additional constructural and operational requirements not specified in the international standard but considered essential in a modern electrometer to be used as a secondary standard are presented.

Diagnosis of attention-deficit/hyperactivity disorder in the office.

The evaluation of the child with ADHD can be a complex and time-consuming process. Because there are no specific diagnostic tests, the physician must rely on the old standard of history and observation. An approach to diagnosis has been outlined in this article, which views ADHD as one of many clinical expressions of a more generalized impairment of neurologic processing. This approach suggest that four separate areas should be investigated: family and medical history, behavior, cognition, and coordination, while searching for signs of impairment in each area. This can provide a framework for the private practitioner to effectively and efficiently evaluate a child for ADHD within a busy office practice.

Management of stimulant medications in children with attention-deficit/hyperactivity disorder.

In the United States, considerable media attention has been given to the growing number of youth diagnosed with ADHD and treated with psychotropic medications. The efficacy of stimulant medications long has been recognized clinically and is well documented in research. Studies suggest that treatment with stimulant therapy, when properly done, is more effective than psychosocial interventions that did not yield any significant benefits on a range of behavioral, emotional, psychosocial, and academic measures. The purpose of this article is to provide clinicians with everything they need to know but were afraid to ask about stimulant therapy for children and adolescents with ADHD.

Commissioning a p-type silicon diode for use in clinical electron beams.

Commissioning measurements were carried out on a p-type silicon diode detector for use in patient monitoring in high energy electron beams. Characteristics specific to the diode were examined. The variation in diode sensitivity with dose per pulse was found to be less than 1% over a range 0.069-0.237 mGy/pulse. The diode exhibited a sensitivity variation with accumulated dose of 10% per kGy and a sensitivity variation with surface temperature of 0.26%/degree C. The dependence of the diode response on the direction of the incident electron beam was investigated. Results were found to exceed the manufacturer's specifications. Output factors measured with the diode agree to within 1.5% of those measured with an NACP-02 air ionization chamber. The detector showed a variation in response with energy of 0.8% over the energy range 4-15 MeV. Prior to introducing the diode into clinical use, an assessment of beam perturbation directly behind the diode was made. The maximum reduction in local dose directly behind the diode at a depth of 1.0 cm below the surface was approximately 13% at 4 and 15 MeV.

Verbal fluency in children: developmental issues and differential validity in distinguishing children with attention-deficit hyperactivity disorder and two subtypes of dyslexia.

Previous research studies have shown that in adults, verbal fluency is impaired after lesion to the frontal lobes and left temporal lobe. More recently, there have been a few studies reported which indicated that in children, like adults, left hemisphere and frontal lesions result in pronounced effects on verbal fluency. The present study examined developmental differences in verbal fluency within a sample of 130 normal children, aged 6 to 12 years. Additionally, the same verbal fluency test was administered to two subgroups of children with developmental dyslexia and a group of children with attention-deficit/hyperactivity disorder (ADHD). Analysis of variance (ANOVA) revealed significant between-group differences by age in the normal children. Further, ANOVA demonstrated that the verbal fluency measure was clinically useful in differentiating the Language Disorder/Dysphonetic Dyslexic subgroup from the Visual-Spatial/Dyseidetic Dyslexic subgroup and the ADHD group, with the latter two groups performing within the average range.

Toxicity and dosimetry of fractionated total body irradiation prior to allogeneic bone marrow transplantation using a straightforward radiotherapy technique.

Since 1989, we have used a relatively straightforward technique for giving total body irradiation (TBI), using anterior and posterior parallel opposed fields with the arms and fists acting as compensators. The dosimetry, toxicity and outcome of 48 patients (26 adults, 22 children) treated with TBI using this technique have been audited. A dose of 14.4 Gy in eight fractions over 4 days was prescribed to all patients with an unrelated donor and 12 Gy in six fractions over 3 days to those with a sibling donor. From May 1994, all children received 14.4 Gy because of a recommendation from the United Kingdom Children's Cancer Study Group. The range of lung dosimetry was -6% to +7% when the dose was specified to the lung maximum. The trunk doses were all within +/-10% of the prescribed dose. Doses to other regions of the body were less homogeneous but clinically acceptable in that the minimum doses were never less than -10% of the prescribed dose. Mucositis was the most common side effect; its treatment with opioids was more frequent after 14.4 Gy than after 12 Gy (P=0.0004) and in adults than in children (P=0.01). No cataracts have yet been seen in these patients. The radiation was not found to be a proven cause of clinical pneumonitis, although there was one death due to interstitial pneumonitis, which was likely to have been caused by cytomegalovirus infection in which radiation pneumonitis could not be excluded. There were no other suspected TBI-related deaths. In conclusion, this straightforward technique achieved acceptable dosimetry and was well tolerated.

Early identification of cerebral palsy using a profile of abnormal motor patterns.

OBJECTIVE: To determine whether a profile of abnormal motor patterns can identify children with cerebral palsy (CP) in the first year of life. METHODS: The Early Motor Pattern Profile (EMPP) consists of 15 items reflecting variations in muscle tone, reflexes, and movement that have been organized into a standardized format to provide the clinician with an objective picture of neurologic status. A three-point scoring system was applied to each item, delineating a clearly normal response from a clearly abnormal one and placing all partial or inconsistent responses in the middle. Twelve hundred forty-seven high-risk infants who were enrolled in a neonatal intensive care unit follow-up program were examined at 6 and/or 12 months' corrected age using the EMPP. These infants were followed to at least 36 months of age to distinguish those with CP from those with normal motor outcome or minimal impairment (no CP). RESULTS: Predictive validity of the EMPP at the 6- and 12-month examinations was determined using various pass-fail cutoffs. The optimal cutoff score at 6 months was between 9 and 10, at which the positive predictive value was 89.4, sensitivity was 87.1, and specificity was 97.8. The optimal cutoff score at 12 months was between 3 and 4, at which the positive predictive value was 91.0, sensitivity was 91.5, and specificity was 97.9. CONCLUSIONS: The EMPP offers the clinician an effective instrument to identify children in the first year of life who are at greatest risk for the development of CP. The EMPP can be incorporated into a routine health maintenance visit, adding only a few minutes to the process, and has high sensitivity and specificity.

Persistent cutaneous larva migrans due to Ancylostoma species.

Cutaneous larva migrans is considered to be a self-limited parasitic infection of about 2 to 8 weeks' duration, though it has been reported to persist for as long as 55 weeks. In this case, a healthy 47-year-old white man had multiple serpiginous lesions typical of cutaneous larva migrans for 18 months. A biopsy taken 2 months before presentation showed a parasite consistent with Ancylostoma species deep in a hair follicle. The patient initially responded to topical thiabendazole, but relapse occurred when therapy was discontinued. Oral thiabendazole cured the problem after 22 months of infestation. Cutaneous larva migrans may sometimes be long-standing, here almost 2 years, even in a healthy patient. Organisms may reside deep in the hair follicles. Topical thiabendazole may not penetrate to this depth, necessitating oral thiabendazole therapy.

Neuroendocrine (Merkel cell) carcinoma with an intraepidermal component.

We present 11 cases of primary neuroendocrine (Merkel cell) carcinoma of the skin with an intraepidermal component that were identified in a larger review of Merkel cell carcinomas. Among these is a case with a follow-up of over 11 years in which the primary lesion appeared as bowenoid dysplasia, with subsequent recurrences as intraepidermal Merkel cell carcinoma with focal tubular differentiation, and then with dermal invasion and lymph node metastasis. In addition to immunohistochemical markers commonly used in the identification of Merkel cell carcinomas (neuron-specific enolase and cytokeratin), these tumors stained with Ber-EP4, an immunohistochemical marker used to identify carcinomas. We believe that these histopathologic and immunohistochemical features further confirm that Merkel cell carcinomas represent an epithelial tumor with the potential for neuroendocrine and adnexal differentiation.

The incidence of deep venous thrombosis in patients with superficial thrombophlebitis of the lower limbs.

PURPOSE: The purpose of this study was, first, to determine the incidence of underlying occult deep venous thrombosis (DVT) in patients with superficial thrombophlebitis and, second, to see if any risk factors are helpful in identifying these patients. METHODS: Forty-four consecutive patients with a clinical and duplex ultrasound-confirmed diagnosis of superficial thrombophlebitis were assessed for DVT. All patients had a duplex ultrasound study of the deep venous system. Standard thrombosis risk factors were assessed for each patient. RESULTS: Ten patients (23%) had DVT. All cases were clinically occult. One patient had propagated thrombus in the common femoral vein. Three patients had popliteal vein thrombi. The remaining patients had calf vein thrombus only. Four of these were not in continuity with the superficial thrombus. The site of the superficial thrombophlebitis was not predictive of DVT. None of the known venous thrombotic risk factors were helpful in identifying patients at risk for DVT. CONCLUSION: Noninvasive deep venous studies are recommended in all patients with lower limb superficial thrombophlebitis because of the high incidence of occult DVT. Patients with DVT can then be treated appropriately.

Spindle cell neoplasms coexpressing cytokeratin and vimentin (metaplastic squamous cell carcinoma).

Spindle cell squamous carcinoma (SCSC) and atypical fibroxanthoma (AFX) are both spindle cell neoplasms (SCN) that usually arise in areas of solar or ionizing radiation of elderly patients. Both lesions have a similar biologic behavior. In addition, the morphologic and ultrastructural similarities found in AFX and the spindle cell component of SCSC, have led some investigators to conclude that these tumors have a similar cell of origin. We studied 15 SCNs with no evidence of epithelial origin and no morphologic epithelial component, that showed immunohistochemical and ultrastructural evidence that would support metaplastic changes of a squamous cell carcinoma to a neoplasm with mesenchymal characteristics.