Intraoperative high-dose rate interstitial irradiation of hepatic metastases from colorectal carcinoma. Results of a phase I-II trial

BACKGROUND

Resection of liver metastases from colorectal carcinoma can be curative. Unresectable but liver-confined metastases might be ablated by high-dose radiation with a similar curative result.

METHODS

At Georgetown University Hospital, 22 patients with unresectable hepatic metastases from colorectal carcinoma underwent 24 interstitial irradiation procedures at laparotomy in a Phase I-II study. A single dose was administered with a high-dose rate iridium-192 afterloader. Dose to the tumor periphery was 20 Gy, 25 Gy, and 30 Gy in 13, 9, and 2 procedures, respectively.

RESULTS

No acute or chronic radiation toxicity has occurred at a median follow-up of 11 months. Median actuarial local control at irradiated sites was 8 months, with 26% actuarial local control at 26 months by computed tomography (CT) or magnetic resonance imaging (MRI) scanning. In the two patients undergoing two procedures each, a second biopsy of previously irradiated areas demonstrated tumor eradication.

CONCLUSIONS

This innovative, radical approach to unresectable colorectal hepatic metastases proved safe. Additional study is needed to determine whether interstitial irradiation is as effective as surgical resection, or whether it alters the natural history of the disease or longevity.

Presenilin 2 is the predominant γ-secretase in microglia and modulates cytokine release

Presenilin 1 (PS1) and Presenilin 2 (PS2) are the enzymatic component of the γ-secretase complex that cleaves amyloid precursor protein (APP) to release amyloid beta (Aβ) peptide. PS deficiency in mice results in neuroinflammation and neurodegeneration in the absence of accumulated Aβ. We hypothesize that PS influences neuroinflammation through its γ-secretase action in CNS innate immune cells. We exposed primary murine microglia to a pharmacological γ-secretase inhibitor which resulted in exaggerated release of TNFα and IL-6 in response to lipopolysaccharide. To determine if this response was mediated by PS1, PS2 or both we used shRNA to knockdown each PS in a murine microglia cell line. Knockdown of PS1 did not lead to decreased γ-secretase activity while PS2 knockdown caused markedly decreased γ-secretase activity. Augmented proinflammatory cytokine release was observed after knockdown of PS2 but not PS1. Proinflammatory stimuli increased microglial PS2 gene transcription and protein in vitro. This is the first demonstration that PS2 regulates CNS innate immunity. Taken together, our findings suggest that PS2 is the predominant γ-secretase in microglia and modulates release of proinflammatory cytokines. We propose PS2 may participate in a negative feedback loop regulating inflammatory behavior in microglia.

Kinetic study of collagen fixation with polyepoxy fixatives

A new biomaterial has been developed by fixing native collagen with a polyepoxy compound (PC) fixative. In this study, bovine internal thoracic arteries were fixed with PC under various conditions to help understand the kinetics of the collagen-PC reactions and optimize the fixation process. At predetermined time intervals, small samples were cut from the arteries to determine the quantities of the remaining unreacted amino acids in the collagen. Temperature, concentration, and solution pH were among the key parameters studied. The overall fixation rate was found to be reaction-rate controlled, as the rate of fixation was relatively slow compared with the rate of diffusion of PC. As might be expected, the reaction rate was favored by a higher temperature, concentration, and solution pH. A kinetic model, with a 2.5th reaction order with respect to the reactive functional groups of collagen and a first order with respect to PC, was developed that gave a good fit to the experimental data. Based on this model, the degree of fixation, X, as a function of time, t, is given by (1 - X)-1.5 = 1 + Kt, where K is a constant related to the initial concentrations and the reaction rate constant.

Effects of nitric oxide on platelet activation during plateletpheresis and in vivo tracking of biotinylated platelets in humans

BACKGROUND

The use of platelet transfusions has risen considerably over the last few years, which leads to the collection and transfusion of a greater number of donor plateletpheresis units. Plateletpheresis activates platelets in platelet concentrates, which determines the degree of the storage lesion subsequently observed.

STUDY DESIGN AND METHODS

As nitric oxide (NO) is a potent inhibitor of platelet aggregation and activation, a placebo-controlled crossover trial was performed in healthy young male volunteers to determine whether the NO-donating compound, sodium nitroprusside (SNP), decreases platelet activation during apheresis and whether activated (p-selectin+) platelets circulate in vivo after transfusion. The study also investigated whether nonradioactive biotin labeling of apheresis platelets is feasible for the study of platelet recovery after transfusion in humans.

RESULTS

Platelet activation increased after plateletpheresis in the platelet components, but SNP did not inhibit platelet activation during apheresis, as measured by the percentage of p-selectin expression and the secretion of soluble p-selectin and RANTES. Only a minor increase in p-selectin+ platelets was seen in peripheral blood at 60 minutes after transfusion of the platelets, a rise that was considerably less than that calculated in p-selectin+ platelets if they all were recovered as activated platelets after transfusion. Biotin-labeled platelets averaged 1.5 percent at 10 minutes after transfusion and increased slowly to 2.6 and 3.4 percent after 60 minutes and 24 hours, respectively (p<0.05).

CONCLUSION

SNP does not decrease platelet activation during apheresis and subsequent storage, and only a minor proportion of activated (p-selectin+) platelets circulate after transfusion in men. Moreover, biotin labeling of PCs can safely be used in humans for the study of platelet recovery after transfusion, and measuring recovery at 1 hour may lead to an underestimation of the true recovery when activated platelets are transfused.

Genomic exploration of the hemiascomycetous yeasts: 14. Debaryomyces hansenii var. hansenii

By analyzing 2830 random sequence tags (RSTs), totalling 2.7 Mb, we explored the genome of the marine, osmo- and halotolerant yeast, Debaryomyces hansenii. A contig 29 kb in length harbors the entire mitochondrial genome. The genes encoding Cox1, Cox2, Cox3, Cob, Atp6, Atp8, Atp9, several subunits of the NADH dehydrogenase complex 1 and 11 tRNAs were unambiguously identified. An equivalent number of putative transposable elements compared to Saccharomyces cerevisiae were detected, the majority of which are more related to higher eukaryote copia elements. BLASTX comparisons of RSTs with databases revealed at least 1119 putative open reading frames with homology to S. cerevisiae and 49 to other genomes. Specific functions, including transport of metabolites, are clearly over-represented in D. hansenii compared to S. cerevisiae, consistent with the observed difference in physiology of the two species. The sequences have been deposited with EMBL under the accession numbers AL436045-AL438874.

Protein recovery from reversed micellar solutions through contact with a pressurized gas phase

We describe a new process for the recovery of encapsulated protein from reversed micellar solution in concentrated form. The method involves desolubilization of the protein by decreasing solvent density through gas dissolution. Under appropriate thermodynamic conditions, the micellar water pool can be converted to clathrate hydrates. Protein recovery is facilitated by clathrate hydrate formation, which causes the desolubilized protein to exist in a solid phase, distinct from the micellar supernatant. The process is carried out without any ionic strength or pH modification.

Impact of measles elimination activities on immunization services and health systems: findings from six countries

BACKGROUND

One of the key concerns in determining the appropriateness of establishing a measles eradication goal is its potential impact on routine immunization services and the overall health system. The objective of this study was to evaluate the impact of accelerated measles elimination activities (AMEAs) on immunization services and health systems in 6 countries: Bangladesh, Brazil, Cameroon, Ethiopia, Tajikistan, and Vietnam.

METHODS

Primary data were collected from key informant interviews and staff profiling surveys. Secondary data were collected from policy documents, studies, and reports. Data analysis used qualitative approaches.

RESULTS

This study found that the impact of AMEAs varied, with positive and negative implications in specific immunization and health system functions. On balance, the impacts on immunization services were largely positive in Bangladesh, Brazil, Tajikistan, and Vietnam, while negative impacts were more significant in Cameroon and Ethiopia.

CONCLUSIONS

We conclude that while weaker health systems may not be able to benefit sufficiently from AMEAs, in more developed health systems, disruptions to health service delivery are unlikely to occur. Opportunities to strengthen the routine immunization service and health system should be actively sought to address system bottlenecks in order to incur benefits to eradication program itself as well as other health priorities.

The efficacy of diaspirin crosslinked hemoglobin solution resuscitation in a model of uncontrolled hemorrhage

Controversy exists whether early aggressive fluid therapy in the setting of uncontrolled hemorrhage worsens outcome by increasing blood loss from injured vessels. Since diaspirin crosslinked hemoglobin (DCLHb) is a vasoactive, oxygen-carrying solution, we compared the effects of DCLHb with other resuscitative fluids on blood loss, hemodynamics, and tissue oxygen delivery in a model of uncontrolled hemorrhage. Anesthetized rats (250-350 g) were subjected to a 50% tail transection and resuscitated 15 minutes later with 1:1 DCLHb, 3:1 lactated Ringer's solution (LR), 1:1 hypertonic saline (7.5% HTS), or 1:1 human serum albumin (8.3% HSA) based on initial volume of blood loss (average 4.7 +/- 0.3 mL/kg). An unresuscitated group served as a control. Cumulative blood loss was measured at 5 hours postresuscitation. By 15 minutes after tail transection, mean arterial pressure (MAP) decreased 19.2 +/- 3.8 mm Hg from the baseline value (102 +/- 5 mm Hg). The DCLHb solution restored and maintained MAP and subcutaneous tissue oxygen tension at baseline values better than all other resuscitative fluids. Although blood loss in DCLHb-treated animals was greater than in unresuscitated animals, it was no different from other resuscitative fluids and less than with HSA. There was no difference in 24-hour survival between all treatment groups. In conclusion, DCLHb elevates MAP but does not exacerbate blood loss or compromise tissue oxygen delivery compared with other resuscitative fluids in this model of uncontrolled hemorrhage.

Effect of castration, DES, flutamide, and the 5 alpha-reductase inhibitor, MK-906, on the growth of the Dunning rat prostatic carcinoma, R-3327

Male rats bearing implants of the Dunning rat prostatic carcinoma, R-3327, were used in a 42-day study to determine the effect of castration or orally administered flutamide (FL), DES (diethylstilbestrol) or the 5 alpha-reductase inhibitor, MK-906, on the growth of this androgen-responsive cancer. The rate of growth and final weights of the tumor and the ventral prostate (VP) were all reduced (P less than 0.05) by castration. Flutamide (25 mg/kg/day) significantly decreased tumor and VP weights in intact rats and castrates given 100 micrograms/day (SC) of testosterone propionate (TP) or dihydrotestosterone propionate (DHTP). It also significantly retarded tumor growth rate in TP- or DHTP-treated castrates and was marginally effective in intact animals. DES (100 micrograms/kg/day) reduced (P less than 0.05) tumor and VP weights of intact rats but did not significantly affect tumor growth rate or weight in castrates given TP or DHTP. These results indicated that the effect of DES on tumor growth is caused by its inhibition of the secretion or release of the gonadotropins necessary for testicular androgen production. MK-906 (25 mg/kg/day) affected neither the gross nor the histomorphology of the tumor in intact rats or castrates given TP or DHTP. Further, it caused no histological changes in the testes of intact rats. It did, however, significantly reduce VP weight in intact animals and TP-treated castrates but not in those given DHTP. This illustrates that the anti-androgenicity of MK-906 stems from its inhibition of DHT formation. The failure of MK-906 to influence tumor growth in the TP-treated castrates strongly suggests that the R-3327 tumor can respond to testosterone directly. If that is true, then its growth is unlikely to be affected by a pure 5 alpha-reductase inhibitor such as MK-906. In ancillary experiments, tumors from MK-906-treated animals were found to have reduced levels of DHT and, when assayed in vitro, to have a reduced capacity to convert [3H]-T to [3H]-DHT.

Topical beta-blocker therapy and central nervous system side effects. A preliminary study comparing betaxolol and timolol

Topical beta-blocking agents have been associated with adverse central nervous system (CNS) effects, including depression, emotional lability, and sexual dysfunction. Two studies were done to determine if patients who develop CNS effects while using timolol maleate would improve with betaxolol hydrochloride. In one study, 18 patients with CNS symptoms during timolol therapy were switched to betaxolol. Sixteen of the 18 patients noted symptomatic improvement with betaxolol. The second study involved seven patients with CNS symptoms during timolol therapy who were entered into a double-masked cross-over study. In two patients CNS symptoms resolved with betaxolol; in three patients symptoms improved; and in one patient symptoms worsened with betaxolol. Although factors influencing beta-blocker activity in the CNS are not well understood, there may be some advantage to a selective agent.

A small proton charge radius from an electron-proton scattering experiment

Elastic electron-proton scattering (e-p) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, r_p. In 2010, a new method using muonic hydrogen atoms¹ found a substantial discrepancy compared with previous results², which became known as the 'proton radius puzzle'. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen^3,4. Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision e-p experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous e-p experiments and enabled measurements at very small forward-scattering angles. Our result, r_p = 0.831 ± 0.007_stat ± 0.012_syst femtometres, is smaller than the most recent high-precision e-p measurement⁵ and 2.7 standard deviations smaller than the average of all e-p experimental results⁶. The smaller r_p we have now measured supports the value found by two previous muonic hydrogen experiments^1,7. In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant⁸-one of the most accurately evaluated fundamental constants in physics.

Comparative chemosensitivity profiles in four human ovarian carcinoma cell lines measuring ATP bioluminescence

cis-Platinum (DDP) and cyclophosphamide are commonly used for the treatment of ovarian cancer; however, survival remains poor. The degree of cytotoxicity of the standard antineoplastic agents DDP, 4-hydroperoxy-cyclophosphamide (4-OH-CTX), mitomycin C (MITOM C), vincristine (VCR), etoposide (VP-16), 5-fluorouracil (5-FU), cytosine arabinoside (ARA-C), and interferon (IF) in four representative ovarian cancer cell lines was studied using the ATP assay, which measures total cell kill. Cell lines CAOV-3, OVCAR-3, SKOV-3, and BG-1, which were derived from both pretreated and untreated patients, were exposed to six different concentrations for 90 min. On Day 7, intracellular ATP determinations were done. Sensitivity was defined as greater than or equal to 50% cell kill at 0.5 x peak plasma concentration as compared to controls. For 4-OH-CTX and ARA-C, 3 and 0.5 micrograms/ml were chosen as 0.5 x reference values. For each drug in each cell line, a highly reproducible dose-response relationship was observed. CAOV-3 cells were sensitive to all drugs except DDP, ARA-C, and IF, and OVCAR-3 cells to all except DDP and IF. SKOV-3 cells were resistant to all agents except VCR, and BG-1 cells to all except MITOM C and 5-FU. The apparent heterogeneic response to antineoplastic agents observed in the above cell lines underscores the importance of assessing individual patients' sensitivity profiles before treatment.

Ectopic expression of a c-kitW42 minigene in transgenic mice: recapitulation of W phenotypes and evidence for c-kit function in melanoblast progenitors

The proto-oncogene c-kit encodes a transmembrane tyrosine kinase receptor that is allelic with the murine white-spotting locus (W). W mutations affect melanogenesis, gametogenesis, and hematopoiesis during development and adult life, and they result from the partial or complete loss of c-kit function. The W42 allele is a W mutation with severe effects in both the homozygous and the heterozygous states. Previous analysis of the W42 allele identified a missense mutation in an essential amino acid of the c-kitW42 kinase domain that abolishes the in vitro kinase activity of the c-kitW42 protein but does not affect its normal expression. These results suggested that the c-kitW42 allele was a dominant negative mutation within the context of c-kit-mediated signal transduction. To further explore the dominant negative characteristics of the W42 mutation, we have generated transgenic mice in which ectopic expression is driven by the human beta-actin promoter (hAP). Two mouse lines carrying the hAP-c-kitW42 transgene show an effect on pigmentation and the number of tissue mast cells. The patchy coat color pattern of the line 695 mice may reflect variable expression of the transgene in melanoblast progenitors and their descendants and, consequently, is indicative of a function for c-kit in early melanoblasts. Germ cell development and erythropoiesis, however, do not appear to be affected by the transgene. Mice expressing the c-kitW42 transgene therefore recapitulate some of the phenotypes of mice with W mutations. These results are therefore in agreement with the molecular basis of the W42 mutation and the dominant-negative characteristics of the c-kitW42 protein product.

A comparative trial of home and hospital psychiatric treatment: financial costs

The financial costs of community-based treatment, stressing home treatment, were compared with the cost of hospital-based treatment during one year. Of 155 patients destined to receive inpatient treatment, 76 were randomly assigned to home treatment, 79 to hospital treatment; the two groups were similar as to important social, demographic, and clinical characteristics. The principal differences between the two treatments concerned the focus of treatment, the locale of treatment, the degree to which continuity of treatment was maintained, and the roles of the respective treatment staffs. Manpower and operating costs, measured in dollars, were estimated in two ways. Either way, hospital-based treatment was more expensive during the year: 64.1% more expensive (+3,250 vs. +1,980 per patient) in the first instance, 108.9% more expensive (+6,750 vs. +3,230 per patient) in the second. With two exceptions during the first month of treatment, the proportions of patients and families receiving either treatment who incurred other costs of treatment were low, and the differences between groups were not significantly different. A higher proportion of patients and families receiving home-based treatment defrayed the cost of the patient's psychotropic drugs; second, a higher proportion of families of patients receiving hospital-based treatment defrayed transportation costs. The proportions of patients and families incurring costs of the consequences of illness were low, and the differences between treatment groups were not significant. We compared this study with similar studies, discussed the generalizability of the results of this study and similar studies, and identified issues for future research.

CHK1 Inhibitor Blocks Phosphorylation of FAM122A and Promotes Replication Stress

While effective anti-cancer drugs targeting the CHK1 kinase are advancing in the clinic, drug resistance is rapidly emerging. Here, we demonstrate that CRISPR-mediated knockout of the little-known gene FAM122A/PABIR1 confers cellular resistance to CHK1 inhibitors (CHK1is) and cross-resistance to ATR inhibitors. Knockout of FAM122A results in activation of PP2A-B55α, a phosphatase that dephosphorylates the WEE1 protein and rescues WEE1 from ubiquitin-mediated degradation. The resulting increase in WEE1 protein expression reduces replication stress, activates the G2/M checkpoint, and confers cellular resistance to CHK1is. Interestingly, in tumor cells with oncogene-driven replication stress, CHK1 can directly phosphorylate FAM122A, leading to activation of the PP2A-B55α phosphatase and increased WEE1 expression. A combination of a CHK1i plus a WEE1 inhibitor can overcome CHK1i resistance of these tumor cells, thereby enhancing anti-cancer activity. The FAM122A expression level in a tumor cell can serve as a useful biomarker for predicting CHK1i sensitivity or resistance.

Effects of contrast dose, delayed imaging, and magnetization transfer saturation on gadolinium-enhanced MR imaging of brain lesions

This paper discusses the types of paramagnetic agents available for clinical brain imaging and reviews investigations that have sought to optimize the use of these agents by varying the administered dose, delaying the imaging time after contrast administration, and altering image contrast by using magnetization transfer saturation pulses.

Role for NOD2 in Mycobacterium tuberculosis-induced iNOS expression and NO production in human macrophages

M.tb, which causes TB, is a host-adapted intracellular pathogen of macrophages. Macrophage intracellular PRRs, such as NOD proteins, regulate proinflammatory cytokine production in response to various pathogenic organisms. We demonstrated previously that NOD2 plays an important role in controlling the inflammatory response and viability of M.tb and Mycobacterium bovis BCG in human macrophages. Various inflammatory mediators, such as cytokines, ROS, and RNS, such as NO, can mediate this control. iNOS (or NOS2) is a key enzyme for NO production and M.tb control during infection of mouse macrophages; however, the role of NO during infection of human macrophages remains unclear, in part, as a result of the low amounts of NO produced in these cells. Here, we tested the hypothesis that activation of NOD2 by its ligands (MDP and GMDP, the latter from M.tb) plays an important role in the expression and activity of iNOS and NO production in human macrophages. We demonstrate that M.tb or M. bovis BCG infection enhances iNOS expression in human macrophages. The M.tb-induced iNOS expression and NO production are dependent on NOD2 expression during M.tb infection. Finally, NF-κB activation is required for NOD2-dependent expression of iNOS in human macrophages. Our data provide evidence for a new molecular pathway that links activation of NOD2, an important intracellular PRR, and iNOS expression and activity during M.tb infection of human macrophages.

Solid-phase extraction of fluoxetine and norfluoxetine from serum with gas chromatography-electron-capture detection

A rapid, selective, and sensitive method is described for the purification and analysis of fluoxetine and norfluoxetine using a solid-phase extraction column and gas chromatography-electron-capture detection. Linear quantitative response curves for fluoxetine and norfluoxetine are generated over a concentration range of 20-200 ng/ml. Overall extraction efficiency of the extraction procedure is found to be greater than 90% and greater than 75% with correlation coefficients of 0.997 and 0.993 for fluoxetine and norfluoxetine, respectively.

Cigarette smoke impairs neutrophil respiratory burst activation by aldehyde-induced thiol modifications

Exposure to airborne pollutants such as tobacco smoke is associated with increased activation of inflammatory-immune processes and is thought to contribute to the incidence of respiratory tract disease. We hypothezised that cigarette smoke (CS) could synergize with activated inflammatory/immune cells to cause oxidative injury or result in the formation of unique reactive oxidants. Isolated human neutrophils were exposed to gas-phase CS, and the production of nitrating and chlorinating oxidants following neutrophil stimulation was monitored using the substrate 4-hydroxyphenylacetate (HPA). Stimulation of neutrophils in the presence of CS resulted in a reduced oxidation and chlorination of HPA, suggesting inhibition of NADPH oxidase or myeloperoxidase (MPO), the two major enzymes involved in inflammatory oxidant formation. Peroxidase assays demonstrated that neutrophil MPO activity was not significantly affected after CS-exposure, leaving the NADPH oxidase as a likely target. The inhibition of neutrophil oxidant formation was found to coincide with depletion of cellular GSH, and a similar modification of critical cysteine residues, such as those in NADPH oxidase components, might be involved in reduced respiratory burst activity. As alpha,beta-unsaturated aldehydes such as acrolein have been implicated in thiol modifications by CS, we exposed neutrophils to acrolein prior to stimulation, and observed inhibition of NADPH oxidase activation in relation to GSH depletion. Additionally, translocation of the cytosolic components of NADPH oxidase to the membrane, a necessary requirement for enzyme activation, was inhibited. Protein adducts of acrolein (or related aldehydes) could be detected in several neutrophil proteins, including NADPH oxidase components, following neutrophil exposure to either CS or acrolein. Alterations in neutrophil function by exposure to (environmental) tobacco smoke may affect inflammatory/infectious conditions and thereby contribute to tobacco-related disease.

Influence of psychiatric diagnoses on interferon-alpha treatment for chronic hepatitis C in a veteran population

OBJECTIVE

The prevalence of psychiatric problems and substance abuse is high in the veteran population with hepatitis C. The purpose of this study was to retrospectively analyze the effect of preexisting psychiatric conditions in veteran patients undergoing treatment with interferon a-2b (IFN-alpha) with respect to adverse events, compliance, and treatment response.

METHODS

Thirty-three veterans with chronic hepatitis C were treated with IFN-alpha (5 million units three times weekly) for 6 months, followed by a tapering dose for an additional 6 months. All patients fulfilled standard criteria for treatment eligibility. Psychiatric diagnoses, adverse events, and virological and biochemical responses to therapy were determined.

RESULTS

Nineteen of 33 (58%) patients with hepatitis C had documented psychiatric conditions before starting IFN-alpha therapy. Of the patients with preexisting psychiatric diagnoses, 13/19 (68%) developed major adverse events requiring intervention or discontinuation of therapy. In contrast, 4/14 (29%) patients without psychiatric diagnoses developed major adverse events (p = 0.024) In the psychiatric group, 6/19 (32%) developed major neuropsychiatric side effects compared with 2/14 patients (14%) in the nonpsychiatric group (p = 0.25). Patients with and without psychiatric diagnoses had equivalent biochemical and virological responses to therapy. Overall, only 2/33 (6%) patients had a sustained virological response.

CONCLUSIONS

Veterans with chronic hepatitis C and psychiatric diagnoses experienced a significantly greater number of major adverse events during treatment with IFN-alpha. Veteran patients with hepatitis C should be carefully screened for psychiatric conditions and may require more intensive monitoring during IFN-alpha therapy.

Deficient expression of DNA repair enzymes in early progression to sporadic colon cancer

Background

Cancers often arise within an area of cells (e.g. an epithelial patch) that is predisposed to the development of cancer, i.e. a "field of cancerization" or "field defect." Sporadic colon cancer is characterized by an elevated mutation rate and genomic instability. If a field defect were deficient in DNA repair, DNA damages would tend to escape repair and give rise to carcinogenic mutations.

Purpose

To determine whether reduced expression of DNA repair proteins Pms2, Ercc1 and Xpf (pairing partner of Ercc1) are early steps in progression to colon cancer.

Results

Tissue biopsies were taken during colonoscopies of 77 patients at 4 different risk levels for colon cancer, including 19 patients who had never had colonic neoplasia (who served as controls). In addition, 158 tissue samples were taken from tissues near or within colon cancers removed by resection and 16 tissue samples were taken near tubulovillous adenomas (TVAs) removed by resection. 568 triplicate tissue sections (a total of 1,704 tissue sections) from these tissue samples were evaluated by immunohistochemistry for 4 DNA repair proteins. Substantially reduced protein expression of Pms2, Ercc1 and Xpf occurred in field defects of up to 10 cm longitudinally distant from colon cancers or TVAs and within colon cancers. Expression of another DNA repair protein, Ku86, was infrequently reduced in these areas. When Pms2, Ercc1 or Xpf were reduced in protein expression, then either one or both of the other two proteins most often had reduced protein expression as well. The mean inner colon circumferences, from 32 resections, of the ascending, transverse and descending/sigmoid areas were measured as 6.6 cm, 5.8 cm and 6.3 cm, respectively. When combined with other measurements in the literature, this indicates the approximate mean number of colonic crypts in humans is 10 million.

Conclusions

The substantial deficiencies in protein expression of DNA repair proteins Pms2, Ercc1 and Xpf in about 1 million crypts near cancers and TVAs suggests that the tumors arose in field defects that were deficient in DNA repair and that deficiencies in Pms2, Ercc1 and Xpf are early steps, often occurring together, in progression to colon cancer.

A toxicity testing protocol using a bioluminescent reporter bacterium from activated sludge

A protocol for production, storage, and use of Shock 1 (Shk1) bioreporter cells for toxicity monitoring in wastewater treatment facilities was developed. Shk1 is a bioluminescent toxicity bioreporter for activated sludge previously constructed by the incorporation of lux genes into an activated sludge microorganism.A number of factors affecting Shk1 growth and bioluminescence were examined including the growth medium, tetracycline concentration, storage conditions, and test media. Based on the results of these experiments, a toxicity testing protocol was developed that involved growth of cultures in nutrient broth with tetracycline, storage of cultures at 4 degrees C, cell activation by reinoculation into nutrient broth, and toxicity testing by cell injection into the test media. Effective use of this approach required standardized time intervals for cell growth, storage, activation and exposure in the test media. Bioluminescence from Shk1 cells was measured in nutrient broth and influent wastewater and activated sludge mixed liquor from a municipal wastewater treatment plant. Using the Shk1 toxicity testing protocol, Zn EC(50) values for bioluminescence in nutrient broth, influent wastewater, and activated sludge mixed liquor were approximately 42, 7, and 32 mg/l, respectively. Zn concentrations as low as 1 mg/l could be detected in influent wastewater. The detection limit in influent wastewater is below the Zn concentrations typically reported to affect the activated sludge process.