The effect of transportation and lairage on faecal shedding and carcass contamination with Escherichia coli O157 and O26 in very young calves in New Zealand.

The effect of transportation and lairage on the faecal shedding and post-slaughter contamination of carcasses with Escherichia coli O157 and O26 in young calves (4-7-day-old) was assessed in a cohort study at a regional calf-processing plant in the North Island of New Zealand, following 60 calves as cohorts from six dairy farms to slaughter. Multiple samples from each animal at pre-slaughter (recto-anal mucosal swab) and carcass at post-slaughter (sponge swab) were collected and screened using real-time PCR and culture isolation methods for the presence of E. coli O157 and O26 (Shiga toxin-producing E. coli (STEC) and non-STEC). Genotype analysis of E. coli O157 and O26 isolates provided little evidence of faecal-oral transmission of infection between calves during transportation and lairage. Increased cross-contamination of hides and carcasses with E. coli O157 and O26 between co-transported calves was confirmed at pre-hide removal and post-evisceration stages but not at pre-boning (at the end of dressing prior to chilling), indicating that good hygiene practices and application of an approved intervention effectively controlled carcass contamination. This study was the first of its kind to assess the impact of transportation and lairage on the faecal carriage and post-harvest contamination of carcasses with E. coli O157 and O26 in very young calves.

Hypoxia and the metabolic phenotype of prostate cancer cells.

Many cancer cells have an unusual ability to grow in hypoxia, but the origins of this metabolic phenotype remain unclear. We compared the metabolic phenotypes of three common prostate cancer cell models (LNCaP, DU145, PC3), assessing energy metabolism, metabolic gene expression, and the response to various culture contexts (in vitro and xenografts). LNCaP cells had a more oxidative phenotype than PC3 and DU145 cells based upon respiration, lactate production, [ATP], metabolic gene expression, and sensitivity of these parameters to hypoxia. PC3 and DU145 cells possessed similar Complex II and mtDNA levels, but lower Complex III and IV activities, and were unresponsive to dinitrophenol or dichloroacetate, suggesting that their glycolytic phenotype is due to mitochondrial dysfunction rather than regulation. High passage under normoxia converted LNCaP from oxidative to glycolytic cells (based on respiration and lactate production), and altered metabolic gene expression. Though LNCaP-derived cells differed from the parental line in mitochondrial enzyme activities, none differed in mitochondrial content (assessed as cardiolipin levels). When LNCaP-derived cells were grown as xenografts in immunodeficient mice, there were elements of a hypoxic response (e.g., elevated VEGF mRNA) but line-specific changes in expression of select glycolytic, mitochondrial and fatty acid metabolic genes. Low oxygen in vitro did not influence the mRNA levels of SREBP axis, nor did it significantly alter triglyceride production in any of the cell lines suggesting that the pathway of de novo fatty acid synthesis is not directly upregulated by hypoxic conditions. Collectively, these studies demonstrate important differences in the metabolism of these prostate cancer models. Such metabolic differences would have important ramifications for therapeutic strategies involving metabolic targets.

Quality of life after surgery, external beam irradiation, or brachytherapy for early-stage prostate cancer.

BACKGROUND: The primary treatments for clinically localized prostate cancer confer equivalent cancer control for most patients but disparate side effects. In the current study, the authors sought to compare health-related quality of life (HRQOL) outcomes after the most commonly used treatments. METHODS: A total of 580 men completed the Medical Outcomes Study Short Form-36, the University of California-Los Angeles (UCLA) Prostate Cancer Index, and the American Urological Association Symptom Index before and through 24 months after treatment with radical prostatectomy (RP), external beam radiation therapy (EBRT), or brachytherapy (BT). RESULTS: General HRQOL did not appear to be affected by treatment. Obstructive and irritative urinary symptoms were more common after BT (P<.001). Urinary control and sexual function were better after EBRT than BT (P<.001 and P=.02, respectively) and better after BT than RP (P<.001 and P=.01, respectively). Among potent men, recovery of sexual function was best after EBRT and was equivalent after bilateral nerve-sparing surgery or BT. Sexual bother was more common than urinary or bowel bother after all 3 treatments. Bowel dysfunction was more common after EBRT or BT than RP (P<.001). CONCLUSIONS: In the current study, treatment for localized prostate cancer was found to differentially affect HRQOL outcomes. Urinary control and sexual function were better after EBRT, although bilateral nerve-sparing surgery diminished these differences among potent men undergoing RP. BT caused more obstructive and irritative symptoms, while both forms of radiation caused more bowel dysfunction. These results may inform medical decision-making in men with localized prostate cancer.

The biological effectiveness of antiproton irradiation.

BACKGROUND AND PURPOSE: Antiprotons travel through tissue in a manner similar to that for protons until they reach the end of their range where they annihilate and deposit additional energy. This makes them potentially interesting for radiotherapy. The aim of this study was to conduct the first ever measurements of the biological effectiveness of antiprotons. MATERIALS AND METHODS: V79 cells were suspended in a semi-solid matrix and irradiated with 46.7MeV antiprotons, 48MeV protons, or (60)Co gamma-rays. Clonogenic survival was determined as a function of depth along the particle beams. Dose and particle fluence response relationships were constructed from data in the plateau and Bragg peak regions of the beams and used to assess the biological effectiveness. RESULTS: Due to uncertainties in antiproton dosimetry we defined a new term, called the biologically effective dose ratio (BEDR), which compares the response in a minimally spread out Bragg peak (SOBP) to that in the plateau as a function of particle fluence. This value was approximately 3.75 times larger for antiprotons than for protons. This increase arises due to the increased dose deposited in the Bragg peak by annihilation and because this dose has a higher relative biological effectiveness (RBE). CONCLUSION: We have produced the first measurements of the biological consequences of antiproton irradiation. These data substantiate theoretical predictions of the biological effects of antiproton annihilation within the Bragg peak, and suggest antiprotons warrant further investigation.

Modeling growth kinetics and statistical distribution of oligometastases.

The kinetics of development of micrometastases, and especially of small numbers of metastases (oligometastases), was explored by using simple assumptions to develop concepts that may be useful for framing future research. The conclusions depend on the assumptions and hence must be considered speculative. It is assumed that beyond a threshold size for initiation of metastatic spread, which varies widely from tumor to tumor, the rate at which a primary tumor sheds new metastases increases exponentially, in parallel with its exponential growth. This increasing rate of release of new metastatic clonogens from the primary tumor is accompanied by a similar exponential growth of each of the micrometastases newly established at a secondary site. This creates a log-log linear relationship between the volume distribution of metastases and number of metastases, there being one largest metastasis followed by an exponentially expanding number of logarithmically smaller micrometastases. For example, if the micrometastases and the primary tumor grew at the same rate for 6 doublings after initiation of the first metastasis, then the primary tumor would have increased its volume by a factor of 64 (2(6)) and would be shedding metastatic clonogens at 64 times the initial rate. The first metastasis would undergo 6 doublings and contain 64 cells; the succeeding 2 metastases, released as the primary doubled in volume, would undergo 5 doublings and each would contain 32 cells; and so forth down to the 64 most recently developed single-cell metastases. However, the growth rate of metastases is expected to be faster than that of the primary tumor so that the rate of increase in volume of the micrometastases would be faster than the rate of increase in their numbers (through release of new metastases from the primary). Thus, although the log-log linear relationship is maintained, the slope of the volume frequency curve is changed; if the micrometastases grew 5 times faster than the primary, the slope would change by a factor of 5. Removal of the primary tumor as a source of new metastases truncates the expansion in numbers of metastases without affecting the growth rate of existing micrometastases, with the result that the volume-frequency relationship is maintained but the whole curve is shifted to larger volumes as micrometastases grow toward clinical detectability. The development of an oligometastatic distribution requires that the exponential expansion in the number of new metastases be stopped by eliminating the primary tumor soon after the first metastasis is shed. A cell destined to become part of an oligometastatic distribution had just been newly deposited at its metastatic site at the time the primary tumor was removed and must undergo about 30 doublings to become clinically detectable as an overt metastasis (2(30) or 10(9) cells). Thus, the time interval between removal of the primary and subsequent appearance of oligometastases will be toward the upper end of a distribution of "metastasis-free" intervals for its particular class of tumor. The actual time to appearance of a solitary metastasis, or of oligometastases, in any particular patient will depend on the growth rate of the metastases in that individual but will always require about 30 volume doublings. An apparently solitary metastasis appearing synchronously with the primary tumor is unlikely to be solitary because, to do so, it would have to have undergone about 30 doublings without further release of metastatic clonogens from the primary that is, in our model, within 1 doubling in volume of the primary tumor. For the same reason, a synchronous or early appearing oligometastatic distribution is unlikely, but if it were to exist, there would be a steep gradient between the volumes of largest and smallest metastases because the growth rate of the micrometastases to produce synchronous metastases, without having further metastases shed from the primary, would have to be fast (up to 30x) relative to the growth rate of the primary. Conversely, a steep gradient in volumes of successive echelons of metastases reflects fast growth of metastases relative to the primary and favors the possibility of an oligometastatic distribution. This ratio of growth rates of metastases to primary is defined by the slope of the log-log curve for the volume-frequency distribution of metastases, which, in clinical practice, is difficult to determine over a wide range and is, by definition, essentially impossible for oligometastases. However, the volume-frequency relationship, measured over a wide range, is the same as the ratio of the volume of the largest to second-largest metastases in an oligometastatic situation. For example, if the metastasis doubled 5 times faster than the primary, the largest metastasis would be larger by 5 doublings than its closest follower(s), that is, by a factor of 2(5) or 32, equivalent to a 3.2-fold difference in diameter if the metastases were spherical. Alternatively, if an initially solitary and measurable metastasis is subsequently joined by measurable followers, the number of volume doublings separating successive echelons in the series can be determined directly, and the larger the difference (measured in doublings), the greater the probability that there will be a limited, oligometastatic condition (ie, in clinical terms, subsequent metastases will stop appearing after the large leader metastasis and a short succession of followers have been removed at 1 or more operations). In summary, the probability of there being an oligometastatic distribution is increased as the interval between removal of the primary tumor and appearance of metastases lengthens. It is also more likely the faster the metastases are growing relative to the growth rate of the primary tumor before its removal. Effective systemic cytotoxic treatment (eg, chemotherapy, hormonal manipulation, biological agents) given in the perioperative period, or concomitantly with radiation therapy for the primary tumor, would truncate the volume-frequency distribution toward an oligometastatic one by eliminating the smallest, most recently formed "tail-ender" metastases. That process, which only occurs at the threshold volume of the primary at which metastases are first initiated, would not be influenced by whether surgery or radiation therapy was chosen to treat the primary tumor, regardless of the overall duration of radiation therapy. Chemotherapy adjuvant to surgery is not usually indicated in the curative treatment of solitary or oligometastases because they represent a truncated distribution with few or no stragglers. If subclinical stragglers exist, they would usually be relatively large and, even though subclinical, too large to be cured by chemotherapy. Exceptions would be early rapidly growing oligometastases, especially from a slowly growing primary, or solitary metastases from an unknown primary where second echelon metastases, if they exist, may still be small. Otherwise chemotherapy could be postponed and used for palliative growth restraint of unusually large and/or numerous stragglers.

The biological basis of fractionation.

A few important concepts in radiobiology are illustred. The cell survival, the concept of the biologically effective dose, the basis of fractionation in radiotherapy are considered. Slow tumor regression after irradiation is not an indication of treatment failure, and the rate of regression is not , in general, prognostic. Dose volume histograms provide many data for predicting tumor control and side effects. The magnitude of a dose reduction in the tumor is the major determinant of decline in tumor control probability. Escalation of dose to hypoxic foci may be beneficial. Basic knowledge of these concepts is essential for daily radiotherapy practice and for all radiation oncologists.

The efficacy of hyperbaric oxygen therapy in the treatment of radiation-induced late side effects.

PURPOSE: We investigated the efficacy of hyperbaric oxygen therapy (HBOT) in the management of patients with radiation-induced late side effects, the majority of whom had failed previous interventions. METHODS AND MATERIALS: Of 105 eligible subjects, 30 had either died or were not contactable, leaving 75 who qualified for inclusion in this retrospective study. Patients answered a questionnaire documenting symptom severity before and after treatment (using Radiation Therapy Oncology Group criteria), duration of improvement, relapse incidence, and HBOT-related complications. RESULTS: The rate of participation was 60% (45/75). Improvement of principal presenting symptoms after HBOT was noted in 75% of head-and-neck, 100% of pelvic, and 57% of "other" subjects (median duration of response of 62, 72, and 68 weeks, respectively). Bone and bladder symptoms were most likely to benefit from HBOT (response rate, 81% and 83%, respectively). Fifty percent of subjects with soft tissue necrosis/mucous membrane side effects improved with HBOT. The low response rate of salivary (11%), neurologic (17%), laryngeal (17%), and upper gastrointestinal symptoms (22%) indicates that these were more resistant to HBOT. Relapse incidence was low (22%), and minor HBOT-related complications occurred in 31% of patients. CONCLUSION: Hyperbaric oxygen therapy is a safe and effective treatment modality offering durable relief in the management of radiation-induced osteoradionecrosis either alone or as an adjunctive treatment. Radiation soft tissue necrosis, cystitis, and proctitis also seemed to benefit from HBOT, but the present study did not have sufficient numbers to reliably predict long-term response.

Where next with preoperative radiation therapy for rectal cancer?

PURPOSE: The basic question for radiation oncologists is what we hope to achieve from treatments that are adjuvant to surgery: better local (pelvic) control and, hopefully, because of that, fewer metastases. Chemotherapy could add to the local effect of irradiation and may also decrease distant metastases directly. Selection criteria for individual treatment could enhance the therapeutic index. LOCAL CONTROL: Total mesorectal excision reduces the incidence of local recurrence, but preoperative (chemo) radiation is still indicated for more advanced tumors (T3-T4) and for lymph node involvement. Pelvic recurrences arise from tumor clonogens residual beyond the surgical margins. Thus, the practice of shrinking fields to boost the dose to the primary tumor makes no sense, except for tumors that invade residual structures, such as the sacrum. Subclinical disease beyond the future surgical margins grows more quickly than the primary tumor, and hence treatment should be as intense as tolerable. A short treatment course (e.g. 5 x 5 Gy) is desirable, but this regimen, which is currently the gold standard, should be compared (as in the recently closed randomized Polish trial) with higher-dose, longer-duration chemoradiotherapy regimens. The recently closed EORTC trial 22921 examines the benefit of pre- and postoperative chemotherapy combined with a long schedule of radiation. Likewise, continuous infusion of a cycle-active agent rather than bolus administration is a logical addition to radiation therapy in the treatment of fast-growing subclinical tumor extensions. SYSTEMIC DISEASE: The reduction in distant metastasis rates attributable to adjuvant chemotherapy varies greatly among reports. If the reduction is of the order of 10-25%, the efficacy of chemotherapy equates to as little as about 5 to 12.5 Gy and not more than 20 Gy of total body irradiation. INTERVAL BETWEEN RADIATION THERAPY AND POSTRADIATION SURGERY: Early excision after preoperative irradiation would be desirable if the primary tumor were still disseminating viable metastatic clonogens. Most tumors do not metastasize until they contain enough viable clonogens to render them clinically detectable. A dose of 10 Gy in 2 Gy fractions reduces at least 30-fold the absolute number of viable clonogens in the primary tumor, to levels that do not yield metastases from the untreated tumor. After a dose of 44-50 Gy in 2 Gy fractions, there is little chance that the surviving tumor clonogens could regrow to a metastasis-yielding volume in any reasonable radiation-surgery interval. Thus there is no tumor-related necessity for early postradiation surgery. The importance of the interval between radiation and surgery is currently being addressed in a Swedish randomized trial. PROGNOSTIC AND PREDICTIVE CHARACTERIZATION: Tumor volume should be included in the staging system. There are many tumor- and host-related characteristics that can be used to fingerprint the tumor to help select appropriate individual treatment.

Time factor and treatment strategies in subclinical disease.

Rational biological development of treatment strategies for subclinical metastases has lagged behind such efforts with primary cancers: most adjuvant therapies for subclinical disease have been developed empirically, based on clinical observation. This paper reviews recent studies that point to rapid growth of subclinical disease. The effect of rapid growth of occult metastases and undetectable extensions of primary cancer is to increase the radiation dose necessary for their elimination if treatment duration is extended. This increase may be evident even when changes are made to short courses of treatment, consistent with no lag time between the start of treatment and rapid growth or regrowth of subclinical tumour deposits. This provides a strong rationale for avoiding gaps or delays in adjuvant treatments and suggest that accelerated regimens of radiation or chemoradiation may be advantageous in the treatment of subclinical disease provided that the total dose can be maintained or not greatly reduced from those used conventionally. Conversely, an escalation of total dose with a concomitant increase in overall treatment duration may not result in improved control rates because the rapid growth of small clonogen deposits might counterbalance the effect of the higher dose.

Initial clinical results of stereotactic radiotherapy for the treatment of craniopharyngiomas.

The efficacy and toxicity of stereotactic radiotherapy (SRT) for the treatment of craniopharyngioma has been retrospectively evaluated in 16 patients. The median tumor diameter was 2.8 cm (range 1.5-6.1) and the median tumor volume was 7.7 cc (range 0.7-62.8). SRT was delivered to a single isocenter using a dedicated 6 MV linear accelerator to patients immobilized with a relocatable stereotactic head frame. The three-year actuarial overall survival was 93% and the rate of survival free of any imaging evidence of progressive disease was 75%. The three-year actuarial survival rates free of solid tumor growth or cyst enlargement were 94% and 81% respectively. Our results suggest that SRT is a safe and effective treatment approach for patients with craniopharyngioma. Long-term follow-up is required to determine whether the normal tissue-sparing inherent with SRT results in reduction of the neurocognitive effects of conventional radiotherapy for craniopharyngioma. SRT can be delivered to craniopharyngioma that may be difficult to treat with stereotactic radiosurgery due to proximity of the optic chiasm. Further clinical experience is necessary to determine the clinical utility of beam shaping in the setting of SRT.

Molecular pathways that modify tumor radiation response.

Aberrant expression of signal transduction molecules in pathways controlling cell survival, proliferation, death, or differentiation are a common feature of all tumors. The identification of the molecules that are involved allows the development of novel tumor-specific strategies. Not surprisingly, targeting these pathways often also results in radiosensitization. The efficacy of such directed therapies may, however, be limited by the heterogeneity and the multiple mutations that are associated with the cancerous state. A more robust alternative may be to target global mechanisms of cellular control. The ubiquitin/proteasome degradation pathway is one candidate for such therapeutic intervention. This pathway is the main posttranscriptional mechanism that controls levels of many short-lived proteins involved in regulation of cell cycle progression, DNA transcription, DNA repair, and apoptosis. Many of these proteins are involved in various malignancies and/or radiation responses. In recent years, proteasome inhibitors have gained interest as a promising new group of antitumor drugs. PS-341, a reversible inhibitor of proteasome chymotryptic activity, is currently being tested in phase I clinical trials. In this study, we show that proteasome inhibition by PS-341 can alter cellular radiosensitivity in vitro and in vivo, in addition to having direct antitumor effects.

Quorum sensing as an integral component of gene regulatory networks in Gram-negative bacteria.

Bacterial cell-to-cell communication (quorum sensing) relies upon the interaction of a small diffusible signal molecule with a sensor or transcriptional activator to couple gene expression with cell population density. In Gram-negative bacteria, it is now clear that N-acylhomoserine lactones bind directly to LuxR homologues and can be synthesized via one of three unrelated bacterial protein families and by transgenic plants. New chemical classes of signal molecules have been identified, some of which exhibit crosstalk with N-acylhomoserine-lactone-mediated quorum sensing. As the determinant of cell population density, quorum sensing is emerging as an integral component of bacterial global gene regulatory networks responsible for facilitating bacterial adaptation to environmental stress. N-acylhomoserine lactones are produced during experimental animal and human infections, and a function beyond quorum sensing has been suggested by their intrinsic immunomodulatory and pharmacological activities.

Biological aspects of conformal therapy.

Both conformal and intensity-modulated radiation therapy have great potential to further increase tumor control rates and decrease morbidity. A homogeneous escalation of 'biological' dose within a tumor should increase the likelihood of local cure, especially within the mid-range (e.g. 15% to 80%) of tumor control rates, and conversely, a lower control rate should follow a homogeneously reduced dose. However, when the dose to critical normal tissues is tightly constrained, the dose distributions within the treatment volume may necessarily be heterogeneous, and the effect on tumor control probability will depend upon the magnitude of over- or underdosage, and on the proportions of the tumor clonogen population receiving higher or lower than the nominal dose. Dose-volume histograms provide a measure of heterogeneity of dose within the planned treatment volume, but tumor control probability is also influenced by other variables, e.g. inherent tumor clonogen radiosensitivity and growth rates during a course of treatment, alpha/beta ratios, oxygenation and clonogen density throughout the target volume. Heterogeneity in these factors introduces heterogeneity in tumor responses and a less steep change in tumor control probability with change in dose, reducing the gains or losses that would be predicted to result from heterogeneity of dose. Similarly, modeling the effect of inhomogeneous dose distributions on estimates of probability of complications in normal tissues is hindered by uncertainty of estimates for alpha/beta ratios, especially for late-responding tissues, and lack of data on volume effects. Although the effects of dose inhomogeneity cannot be presented with sufficiently reliable quantitation to be directly applicable to dose prescriptions in radiation therapy, the relative influences of heterogeneities in dose and volume can be modeled to provide a framework for clinical decision-making. The magnitude of a dose reduction is the major determinant of decline in tumor control probability. A large dose reduction to even a small volume of tumor can profoundly decrease tumor control probability. Conversely, the most rapid improvement in tumor control probability occurs the closer to 100% the amount of tumor exposed to an increased dose. Escalation of dose is of little value unless it is distributed through most of the tumor: even very large increases in dose to small volumes are of little benefit.

Evidence-based management of groin hernia in primary care--a systematic review.

BACKGROUND: National clinical guidelines on the surgical management of groin hernia have been published by the Royal College of Surgeons of England. There is also a need for guidance on the management of pre- and post-hernia repair patients in primary care, in areas such as diagnosis, referral and advice on recuperation. OBJECTIVE: The purpose of the present study was to determine best practice in primary care aspects of managing groin hernia in adults, by examination of the evidence base. METHOD: A systematic review of the available evidence was carried out, searching the major electronic databases: Medline, the Cochrane Library, Embase, Assia, Helmis, Cinahl and Psyclit. Key search terms were hern$, inguinal, femoral, groin, truss$, with searches limited to human adult subjects and the English language. RESULTS: Robust research on groin hernia is concerned almost exclusively with the in-patient surgical management of patients undergoing primary elective hernia repair. The areas with which this review was concerned, principally diagnosis, referral and advice about return to work, are areas in which it is more difficult to conduct robustly designed studies. Perhaps because of this, the evidence base on the non-surgical aspects of management is of poor methodological quality, being based primarily on expert opinion, reviews of clinical practice and experience, surveys, descriptive case studies and clinical audits. CONCLUSIONS: As the research in this area is generally of poor quality, strong conclusions are precluded, but it is possible to define best practice in some areas of care. In relation to diagnosis, GPs should distinguish correctly between a femoral and inguinal hernia because of the increased risks of strangulation and incarceration associated with the former. Due to clinical inaccuracy, the identification of whether a hernia is direct or indirect is not a good basis on which to base decision making regarding referral for elective repair. The risks associated with surgical repair are those of the normal range found for any procedure. Decisions about the fitness of patients for surgery in this instance are not procedure specific, and therefore the decisions about elective repair especially in older patients should be considered in terms of quality of life and patient choice rather than increased risks with surgical repair. Further research is required to address the gap in the evidence for the management of groin hernia within the primary care sector.