The need for future surgical low rectal cancer studies

Optimal surgery remains the mainstay of best outcome for rectal cancer. The demonstration, during the 3rd Annual Pelican Surgical Workshop Symposium, of an abdomino‐perineal excision (APE) performed in the ‘Berlin position’, further added to the debate on optimal surgical technique. Much interest was created at the 1st Pelican symposium with the demonstration, by the Swedish surgeon Dr Torbjorn Holm, of a prone APE and the delivery of a ‘cylindrical’ specimen and the potential to reduce local recurrence using this approach. The high rates of local recurrence following APE and the discussions as to optimal technique have led to the development of a proposed MERCURY Study Group study to assess the benefit of a radical APE, with careful assessment of the impact that this operation may have on morbidity. A German study has also been proposed adopting the UK's multidisciplinary team approach. It aims at targeting preoperative chemoradiotherapy at those patients in whom a radical APE or total mesorectal excision is likely to result in an involved surgical resection margin. In this article we review the evidence for improving the surgical technique for low rectal cancer. We believe improvements may be best achieved through continued European prospective, multi‐centre, multidisciplinary studies.     

Macroscopic geometric heterogeneity effects in radiation dose distribution analysis for boron neutron capture therapy.

Calculations of radiation flux and dose distributions for boron neutron capture therapy (BNCT) of brain tumors are typically performed using sophisticated three-dimensional analytical models based on either a homogeneous approximation or a simplified few-region approximation to the actual highly heterogeneous geometry of the irradiation volume. Such models should be validated by comparison with calculations using detailed models in which all significant macroscopic tissue heterogeneities and geometric structures are explicitly represented as faithfully as possible. This paper describes such a validation exercise for BNCT of canine brain tumors. Geometric measurements of the canine anatomical structures of interest for this work were performed by dissecting and examining two essentially identical Labrador retriever heads. Chemical analyses of various tissue samples taken during the dissections were conducted to obtain measurements of elemental compositions for the tissues of interest. The resulting geometry and tissue composition data were then used to construct a detailed heterogeneous calculational model of the Labrador head. Calculations of three-dimensional radiation flux distributions pertinent to BNCT were performed for this model using the TORT discrete-ordinates radiation transport code. The calculations were repeated for a corresponding volume-weighted homogeneous-tissue model. Comparison of the results showed that peak neutron and photon flux magnitudes were quite similar for the two models (within 5%), but that the spatial flux profiles were shifted in the heterogeneous model such that the fluxes in some locations away from the peak differed from the corresponding fluxes in the homogeneous model by as much as 10%-20%. Differences of this magnitude can be therapeutically significant, emphasizing the need for proper validation of simplified treatment planning models.     

The striatal-enriched protein tyrosine phosphatase gates long-term potentiation and fear memory in the lateral amygdala.

BACKGROUND: Formation of long-term memories is critically dependent on extracellular-regulated kinase (ERK) signaling. Activation of the ERK pathway by the sequential recruitment of mitogen-activated protein kinases is well understood. In contrast, the proteins that inactivate this pathway are not as well characterized. METHODS: Here we tested the hypothesis that the brain-specific striatal-enriched protein tyrosine phosphatase (STEP) plays a key role in neuroplasticity and fear memory formation by its ability to regulate ERK1/2 activation. RESULTS: STEP co-localizes with the ERKs within neurons of the lateral amygdala. A substrate-trapping STEP protein binds to the ERKs and prevents their nuclear translocation after glutamate stimulation in primary cell cultures. Administration of TAT-STEP into the lateral amygdala (LA) disrupts long-term potentiation (LTP) and selectively disrupts fear memory consolidation. Fear conditioning induces a biphasic activation of ERK1/2 in the LA with an initial activation within 5 minutes of training, a return to baseline levels by 15 minutes, and an increase again at 1 hour. In addition, fear conditioning results in the de novo translation of STEP. Inhibitors of ERK1/2 activation or of protein translation block the synthesis of STEP within the LA after fear conditioning. CONCLUSIONS: Together, these data imply a role for STEP in experience-dependent plasticity and suggest that STEP modulates the activation of ERK1/2 during amygdala-dependent memory formation. The regulation of emotional memory by modulating STEP activity may represent a target for the treatment of psychiatric disorders such as posttraumatic stress disorder (PTSD), panic, and anxiety disorders.     

Antiinflammatory agents. 4. Syntheses and biological evaluation of potential prodrugs of 2-amino-3-benzoylbenzeneacetic acid and 2-amino-3-(4-chlorobenzoyl)benzeneacetic acid

A series of potential prodrugs of 2-amino-3-benzoylbenzeneacetic acid (amfenac) and 2-amino-3-(4-chlorobenzoyl)benzeneacetic acid were synthesized and evaluated for their cyclooxygenase inhibiting properties, antiinflammatory potency, and gastrointestinal irritation liability. One compound, 2-amino-3-(4-chlorobenzoyl)benzeneacetamide, possessed a therapeutic index 1 order of magnitude greater than that of indomethacin.     

A dideazatetrahydrofolate analogue lacking a chiral center at C-6, N-[4-[2-(2-amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5- yl)ethyl]benzoyl]-L-glutamic acid, is an inhibitor of thymidylate synthase.

N-[4-[2-(2-Amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5- yl)ethyl]benzoyl]-L-glutamic acid (15), prepared in five steps from 2-pivaloyl-7-deazaguanine, has been found to be an antitumor agent with its primary site of action at thymidylate synthase rather than purine synthesis. This compound appears to be a promising candidate for clinical evaluation.     

Rapid sequence treatment of advanced squamous cell carcinoma of the upper aerodigestive tract: A pilot study

A review of the literature suggested that prolonged treatment time may lessen the probability of cure for patients with advanced squamous cell carcinoma of the upper aerodigestive tract. To shorten treatment time, rapid sequence treatment (RST) was devised in which chemotherapy, surgery, and irrada-tion were administered in a total treatment time of 8 weeks. Twelve patients were treated and followed 3 years or longer. Medical complications were minor. Osteonecrosis occurred in each of the first five patients and was the only major complication of the protocol. Surgical techniques were modified, and no additional patient developed osteonecrosis. No patient developed local or regional recurrence. Two patients developed distant metastases and three other patients developed second primaries. Absolute survival was 50%. Rapid sequence treatment is an aggressive and potentially hazardous protocol that yielded encouraging results in this pilot study.     

Injury of rat renal vessels following extracorporeal shock wave treatment.

The locations of extracorporeal shock wave treatment induced renal vascular injury and the sources of significant renal hemorrhage were determined in a rat model by means of two different vascular casting procedures. Silicone-rubber injected vascular preparations for light microscopy or corrosion casts for scanning electron microscopy were made following gross examination of the treated organs and their contralateral controls. After 1000 shock waves at 18 kV, five out of 20 treated kidneys appeared to be normal or minimally affected, while 15 showed gross evidence of marked vascular injury. Gross interstitial hemorrhage (15/20), subcapsular hematomas (7/20), and hemorrhages into the renal pelvis (5/20) were confirmed by extravasations of casting materials. These could be traced back to their vascular sources in several instances. Disruptions of interlobar and arcuate veins gave rise to most significant interstitial, subcapsular, and renal pelvic extravasations. On a microscopic scale cortical venules were among the most frequently injured vessels. The arterial vasculature was not spared. Arterial injury ranged from complete arcuate occlusion to small afferent arteriolar and glomerular capillary extravasations. The significance of shock wave induced vascular injury is discussed with respect to potential clinical side effects of ESWL.     

Conservatively Treated Breast Cancer: Outcome by Histologic Subtype

Abstract: Between 1970 and 1990, 1,008 patients with early-stage breast cancer were treated by conservative surgery without axillary dissection followed by radiation therapy to the intact breast in the Department of Therapeutic Radiology at Yale-New Haven Hospital. The patient population, broken down by histologic subtype, was as follows: 761 patients presented with infiltrating ductal carcinoma, 70 patients with pure intraductal, 38 intraductal with focal invasion, 54 infiltrating lobular, 21 tubular, 17 medullary, 16 mucinous, and 29 with other various histologic subtypes. Patients were followed on a regular basis by the referring physicians and radiation oncologists. Diagnostic studies for distant metastases were performed as clinically indicated. Annual mammography was a routine component of the follow-up program. As of 3/96, with a median follow-up of 10.5 years, 83 patients developed an ipsilateral breast tumor recurrence, and 109 patients developed distant metastases resulting in an overall 10-year breast recurrence-free rate of 84%, and a 10-year distant metastasis-free rate of 78%. There were significant differences in clinical stage, pathological nodal involvement, and administration of systemic therapy between various histologic subtypes. As expected, those patients with histologies of low metastatic potential (such as intraductal, tubular, and mucinous) had significantly superior distant recurrence-free survival rates. With respect to breast relapse rates, there were no statistically significant differences in the 5- and 10-year breast recurrence-free rates between any of the histologic subtypes. Patients with intraductal carcinoma with or without focal invasion had similar breast relapse rates as those with other histologic subtypes. Patients with lobular carcinoma in situ as a histologic component also had a similar overall breast relapse-free recurrence rate. In conclusion, long-term follow-up of conservatively treated breast cancer patients demonstrates no significant differences in ipsilateral breast tumor recurrence rates between various histologic subtypes. There are no histologies which had a statistically significantly higher breast-relapse rate than infiltrating ductal carcinomas and therefore no primary histologic subtype represents a relative contraindication to breast conservation therapy.