Urine Extracellular Vesicle GATA2 mRNA Discriminates Biopsy Result in Men with Suspicion of Prostate Cancer

PURPOSE

Prostate specific antigen has limited performance in detecting prostate cancer. The transcription factor GATA2 is expressed in aggressive prostate cancer. We analyzed the predictive value of urine extracellular vesicle GATA2 mRNA alone and in combination with a multigene panel to improve detection of prostate cancer and high risk disease.

MATERIALS AND METHODS

GATA2 mRNA was analyzed in matched extracellular vesicles isolated from urines before and after prostatectomy (16) and paired urine and tissue prostatectomy samples (19). Extracellular vesicle GATA2 mRNA performance to distinguish prostate cancer and high grade disease was tested in training (52) and validation (165) cohorts. The predictive value of a multigene score including GATA2, PCA3 and TMPRSS2-ERG (GAPT-E) was tested in both cohorts.

RESULTS

Confirming its prostate origin, urine extracellular vesicle GATA2 mRNA levels decreased significantly after prostatectomy and correlated with prostate cancer tissue GATA2 mRNA levels. In the training and validation cohort GATA2 discriminated prostate cancer (AUC 0.74 and 0.66) and high grade disease (AUC 0.78 and 0.65), respectively. Notably, the GAPT-E score improved discrimination of prostate cancer (AUC 0.84 and 0.72) and high grade cancer (AUC 0.85 and 0.71) in both cohorts when compared with each biomarker alone and PT-E (PCA3 and TMPRSS2-ERG). A GAPT-E score for high grade prostate cancer would avoid 92.1% of unnecessary prostate biopsies, compared to 61.9% when a PT-E score is used.

CONCLUSIONS

Urine extracellular vesicle GATA2 mRNA analysis improves the detection of high risk prostate cancer and may reduce the number of unnecessary biopsies.

Cell cycle-coupled expansion of AR activity promotes cancer progression

The androgen receptor (AR) is required for prostate cancer (PCa) survival and progression, and ablation of AR activity is the first line of therapeutic intervention for disseminated disease. While initially effective, recurrent tumors ultimately arise for which there is no durable cure. Despite the dependence of PCa on AR activity throughout the course of disease, delineation of the AR-dependent transcriptional network that governs disease progression remains elusive, and the function of AR in mitotically active cells is not well understood. Analyzing AR activity as a function of cell cycle revealed an unexpected and highly expanded repertoire of AR-regulated gene networks in actively cycling cells. New AR functions segregated into two major clusters: those that are specific to cycling cells and retained throughout the mitotic cell cycle ('Cell Cycle Common'), versus those that were specifically enriched in a subset of cell cycle phases ('Phase Restricted'). Further analyses identified previously unrecognized AR functions in major pathways associated with clinical PCa progression. Illustrating the impact of these unmasked AR-driven pathways, dihydroceramide desaturase 1 was identified as an AR-regulated gene in mitotically active cells that promoted pro-metastatic phenotypes, and in advanced PCa proved to be highly associated with development of metastases, recurrence after therapeutic intervention and reduced overall survival. Taken together, these findings delineate AR function in mitotically active tumor cells, thus providing critical insight into the molecular basis by which AR promotes development of lethal PCa and nominate new avenues for therapeutic intervention.

Integrative molecular profiling of routine clinical prostate cancer specimens

BACKGROUND

Comprehensive molecular profiling led to the recognition of multiple prostate cancer (PCa) molecular subtypes and driving alterations, but translating these findings to clinical practice is challenging.

PATIENTS AND METHODS

We developed a formalin-fixed paraffin-embedded (FFPE) tissue compatible integrative assay for PCa molecular subtyping and interrogation of relevant genetic/transcriptomic alterations (MiPC). We applied MiPC, which combines capture-based next generation sequencing and quantitative reverse transcription PCR (qRT-PCR), to 53 FFPE PCa specimens representing cases not well represented in frozen tissue cohorts, including 8 paired primary tumor and lymph node metastases. Results were validated using multiplexed PCR based NGS and Sanger sequencing.

RESULTS

We identified known and novel potential driving, somatic mutations and copy number alterations, including a novel BRAF T599_V600insHT mutation and CYP11B2 amplification in a patient treated with ketoconazole (a potent CYP11B2 inhibitor). qRT-PCR integration enabled comprehensive molecular subtyping and provided complementary information, such as androgen receptor (AR) target gene module assessment in advanced cases and SPINK1 over-expression. MiPC identified highly concordant profiles for all 8 tumor/lymph node metastasis pairs, consistent with limited heterogeneity amongst driving events. MiPC and exome sequencing were performed on separately isolated conventional acinar PCa and prostatic small cell carcinoma (SCC) components from the same FFPE resection specimen to enable direct comparison of histologically distinct components. While both components showed TMPRSS2:ERG fusions, the SCC component exclusively harbored complete TP53 inactivation (frameshift variant and copy loss) and two CREBBP mutations.

CONCLUSIONS

Our results demonstrate the feasibility of integrative profiling of routine PCa specimens, which may have utility for understanding disease biology and enabling personalized medicine applications.

Relationship between the loss of the retinoblastoma tumor suppressor and radiosensitivity

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Background: Prostate cancer is the most frequently diagnosed malignancy and the second leading cause of cancer death in U.S. men. The retinoblastoma tumor suppressor protein, RB, plays a critical role in cell cycle regulation. Loss of RB has been observed in 25–30% of prostate cancers and is correlated with increasing tumor stage and grade. The clinical consequences of RB loss are unknown. We have previously shown that RB loss results in a castrate resistant phenotype. We hypothesized that RB loss would downregulate the G1-S cell cycle arrest normally induced by irradiation, inhibit DNA repair, and subsequently sensitize cells to mitotic catastrophe.

Methods: Experimental work was performed with multiple isogenic prostate cancer cell lines (hormone sensitive: LNCaP and LAP-C4 cells and hormone resistant C42 cells; stable knockdown of RB using shRNA). Gamma H2AX assays were used to quantitate DNA damage and PARP cleavage and Caspase 3 were used to quantitate apoptosis. FACS analysis with BrdU was used to assess the cell cycle. Cell survival was measured using the clonogenic cell survival assay. In vivo work was performed in nude mice with tumor xenografts.

Results: We observed that loss of RB increased radioresponsiveness in both transient and clonogenic cell survival assays in all cell lines (p<0.05). Cell death was not mediated through increased apoptosis, however, there was increased cell cycling despite the presence of DNA damage in the RB knockdown cells. In vivo xenografts of the RB deficient tumors exhibited diminished tumor mass, lower PSA kinetics and decreased tumor growth after treatment with single fraction of ionizing radiation in comparison to RB intact tumors (p<0.05).

Conclusions: Loss of RB results in a differential response to ionizing radiation. Isogenic cells with RB knockdown are more sensitive to DNA damage and result in reduced cell survival. RB status is integral to determining which therapeutic modality should be employed in the management of prostate cancer.

No significant financial relationships to disclose.

Cyclin D1 promotes anchorage-independent cell survival by inhibiting FOXO-mediated anoikis

O-class forkhead box (FOXO) transcription factors are critical regulators of diverse cellular processes, including apoptosis, cell-cycle arrest, DNA damage repair and oxidative stress resistance. Here, we show that FOXO1 and FOXO3a have an essential function in promoting cell detachment-induced anoikis, resistance to which is implicated in cancer development and metastasis. In contrast, the oncoprotein cyclin D1 inhibits anoikis. We further show that cyclin D1 interacts with FOXO proteins and impedes their transcriptional regulatory and anoikis-promoting functions. This effect of cyclin D1 requires its transcription repression domain but is independent of cyclin-dependent kinases CDK4 and CDK6. Moreover, we show that cancer-derived mutants of cyclin D1 are much more stable than wild-type cyclin D1 under anchorage-independent conditions and possess a greater antagonistic effect on FOXO-regulated anoikis and anchorage-independent growth of cancer cells. These data suggest that cyclin D1 may have a critical function in tumorigenesis and cancer metastasis by inhibiting the anoikis-promoting function of FOXO proteins.

Impact of differential cyclin D1 expression and localisation in prostate cancer

Cyclin D1 is a critical regulator of androgen-dependent transcription and cell cycle progression in prostate cancer cells. Despite the influence of D-type cyclins on prostate cancer proliferation, few studies have examined the expression of cyclin D1 in localised tumours or challenged its relevance to disease progression. Cyclin D1 status was characterised using immunohistochemistry in 38 non-neoplastic prostate samples, 138 primary human prostate carcinomas, and three lymph node metastatic specimens. Relevance of cyclin D1 to preoperative prostate-specific antigen (PSA) levels, Ki-67 index, and p21^Cip1 status was also examined. Cyclin D1-positive phenotype was increased in primary carcinoma compared to non-neoplastic tissue, and was evident in all lymph node metastases cases. Interestingly, at least three distinct localisation patterns were observed in the cyclin D1-positive cohort, wherein cytoplasmic localisation was identified in a large fraction, and this pattern was predominant in lower grade tumours. Relevance of altered cyclin D1 status was observed, wherein cyclin D1-positive tumours were associated with low preoperative PSA levels, consistent with in vitro reports that cyclin D1 may alter the expression of this tumour marker. Moreover, tumours with predominantly cytoplasmic cyclin D1 showed the lowest Ki-67 index, whereas nuclear cyclin D1 was associated with higher grade, elevated Ki-67, and increased nuclear p21^Cip1. These data demonstrate that differential cyclin D1 status may influence clinicopathological parameters, and reveal new insight as to the regulation and potential consequence of cyclin D1 expression in prostate cancer.

Cyclin D1: polymorphism, aberrant splicing and cancer risk

The cyclin D1 proto-oncogene exercises powerful control over the mechanisms that regulate the mitotic cell cycle, and excessive cyclin D1 expression and/or activity is common in human cancers. Although somatic mutations of the cyclin D1 locus are rarely observed, mounting evidence demonstrates that a specific polymorphism of cyclin D1 (G/A870) and a protein product of a potentially related alternate splicing event (cyclin D1b) may influence cancer risk and outcome. Herein, we review the epidemiological and functional literatures that link these alterations of cyclin D1 to human tumor development and progression.

Xenoestrogen action in breast cancer: impact on ER-dependent transcription and mitogenesis

Several estrogen mimics (xenoestrogens) inappropriately activate the estrogen receptor (ER) in the absence of endogenous ligand. Given the importance of the ER in breast cancer growth and regulation, delineating the impact of these agents under conditions related to tumor treatment is of significant importance. We examined the effect of two prevalent xenoestrogens (bisphenol A and coumestrol) on ER activation and ER-dependent mitogenesis in breast cancer cells. We show that the ability of these agents to induce mitogenesis was restricted to conditions of estrogen depletion, and that these agents failed to cooperate with estradiol to induce MCF-7 breast cancer cell growth. These observations are consistent with the impact of each agent specifically on exogenous ER activation as monitored in HeLa cells, wherein the xenoestrogens activated the receptor in the absence of estradiol but failed to cooperate with estrogen. Tamoxifen blocked bisphenol A and coumestrol-mediated ER activation, indicating that exposure to these agents is unlikely to disrupt such therapeutic intervention. The response of tumor-derived ER alleles to these xenoestrogens was also examined. Although the xenoestrogens failed to alter ER-Y537S function, the ER-D351Y mutant demonstrated an enhanced response to bisphenol A. Moreover, tamoxifen enhanced the agonistic effects of xenoestrogens on ER-D351Y. Lastly, we examined the impact of ER co-activator overexpression on xenoestrogen response. Bisphenol A and coumestrol exhibited differential responses to co-activators with regard to ER activation. However, when using mitogenesis as an endpoint, these co-activators were insufficient to provide a significant growth advantage. Combined, these data demonstrate that bisphenol A and coumestrol can impact ER activity and ER-dependent proliferation in breast cancer cells, but the influence of these agents is restricted to conditions of estrogen depletion, selective mutation of the ER, and expression of specific co-activators.

Endocrine disrupting compounds and prostate cancer

Prostate cancer is a major health concern and is treated based on its hormone dependence. Agents that alter hormone action can have substantial biological effects on prostate cancer development and progression. As such, there is significant interest in uncovering the potential effects of endocrine disrupting compound (EDC) exposure on prostate cancer. The present review is focused on agents that alter hormone action in the prostate and how they may impact cancer growth or treatment.

Cyclin D1 binding to the androgen receptor (AR) NH2-terminal domain inhibits activation function 2 association and reveals dual roles for AR corepression

The androgen receptor (AR) is a member of the nuclear receptor superfamily, the activity of which is critical for the development and progression of prostate cancer. We and others have previously demonstrated that cyclin D1 is a potent corepressor of the AR. Although cyclin D1 is suspected to recruit histone deacetylases to the AR complex, previous studies have demonstrated that this activity alone is insufficient for cyclin D1 function. Here, we uncover a novel, secondary means of cyclin D1-mediated repression, through modulation of AR amino-carboxy terminal interactions. We show that cyclin D1 predominantly binds the N-terminal domain of the AR, dependent on the AR 23FxxLF27 motif. Through this motif, cyclin D1 abrogates the ability of the AR N-terminal domain to interact with the C terminus. Secondary amino-terminal domain sites capable of fostering interaction with the C terminus were refractory to cyclin D1 action, indicating that the ability of cyclin D1 to modulate AR amino-carboxy terminal interactions is specific to 23FxxLF27. Deletion of the N-terminal cyclin D1 binding site severely compromised AR activity (due to loss of FxxLF) but unmasked a repressor action through interaction with the AR C terminus. In summary, these data reveal novel, unexpected mechanisms of cyclin D1 activity and demonstrate that this function of cyclin D1 is critical for AR modulation.

Impact of diets varying in dietary fibre characteristics on gastric emptying in pregnant sows

The effects of feeding two fibre-rich diets with contrasting solubility and a concentrated low dietary fibre on the rate of gastric emptying were examined in six gastric cannulated pregnant sows. Additionally, it was examined whether any effect could be related to the physico-chemical properties of digesta, i.e. viscosity and/or water binding capacity. The sows were fed each diet for one week in a 3 x 3 Latin Square design and the samples were taken in a randomised order 0.5, 1, 2, 3, 5 and 15.5 h after the morning meal. The stomach contents were evacuated through the gastric cannula once daily. The evacuated gastric digesta was quantified and a representative sample was taken to determine its viscosity, water binding capacity and its content of dry matter, dietary components and solid (Cr2O3) and liquid (polyethylene glycol) phase markers. The flow of liquid digesta was calculated as the difference between digesta and dry matter. Increasing the content of dietary fibre in the diet led to higher recovery of liquid digesta but did not have any significant effect on the gastric emptying of dry matter and dietary components. The effect of dietary fibre could not be attributed to the viscosity of the liquid phase of digesta but might be related to the ability of the increased gastric dietary fibre content to hold water. The stomach selectively retained the insoluble dietary fibre components most noticeably seen with the bran-supplemented diet where the concentration of insoluble NSP in digesta increased significantly from 2 hours and onward.

The effect of dietary carbohydrates with different digestibility on the populations of Oesophagostomum dentatum in the intestinal tract of pigs

An experiment was undertaken to study the effect of dietary carbohydrates with different digestibility on the populations of Oesophagostomum dentatum in the intestinal tract of pigs. Sixty-four worm-free pigs from a specific pathogen-free farm were randomly divided into 8 equal groups. The animals in 4 groups were assigned to a diet with partially undegradable carbohydrates (diet 1), while the pigs in the 4 remaining groups were given a diet with fermentable carbohydrates (diet 2). Diet 1 was comprised of barley flour, oat husk meal, soybean meal, vitamins and minerals and diet 2 of barley flour, inulin and sugar beet fibre, soybean meal, vitamins and minerals. The pigs in 6 of the groups (n = 48) were inoculated with 6,000 infective larvae of O. dentatum. To determine O. dentatum populations at the early stage of infection, 16 pigs were slaughtered 3 weeks p.i., while the remaining 4 groups continued on the diets for a further 9 weeks after which they were slaughtered. In a diet cross-over experiment 6 weeks after inoculation, 8 pigs changed from diet 1 to diet 2 (diet 1 > diet 2), and 8 pigs from diet 2 to diet 1 (diet 2 > diet 1). The results showed that partially undegradable carbohydrates provided favourable conditions not only for parasite establishment and sustainability, but also for already established O. dentatum infection while, in contrast, the diet composed of highly degradable carbohydrates decreased worm establishment, size and female fecundity. The implications for pastured pigs or pigs fed different complex carbohydrate diets is discussed.

Retinoblastoma tumor suppressor protein signals through inhibition of cyclin-dependent kinase 2 activity to disrupt PCNA function in S phase

The retinoblastoma tumor suppressor protein (RB) is a negative regulator of the cell cycle that inhibits both G(1) and S-phase progression. While RB-mediated G(1) inhibition has been extensively studied, the mechanism utilized for S-phase inhibition is unknown. To delineate the mechanism through which RB inhibits DNA replication, we generated cells which inducibly express a constitutively active allele of RB (PSM-RB). We show that RB-mediated S-phase inhibition does not inhibit the chromatin binding function of MCM2 or RPA, suggesting that RB does not regulate the prereplication complex or disrupt early initiation events. However, activation of RB in S-phase cells disrupts the chromatin tethering of PCNA, a requisite component of the DNA replication machinery. The action of RB was S phase specific and did not inhibit the DNA damage-mediated association of PCNA with chromatin. We also show that RB-mediated PCNA inhibition was dependent on downregulation of CDK2 activity, which was achieved through the downregulation of cyclin A. Importantly, restoration of cyclin-dependent kinase 2 (CDK2)-cyclin A and thus PCNA activity partially restored S-phase progression in the presence of active RB. Therefore, the data presented identify RB-mediated regulation of PCNA activity via CDK2 attenuation as a mechanism through which RB regulates S-phase progression. Together, these findings identify a novel pathway of RB-mediated replication inhibition.

RB-dependent S-phase response to DNA damage

The retinoblastoma tumor suppressor protein (RB) is a potent inhibitor of cell proliferation. RB is expressed throughout the cell cycle, but its antiproliferative activity is neutralized by phosphorylation during the G(1)/S transition. RB plays an essential role in the G(1) arrest induced by a variety of growth inhibitory signals. In this report, RB is shown to also be required for an intra-S-phase response to DNA damage. Treatment with cisplatin, etoposide, or mitomycin C inhibited S-phase progression in Rb(+/+) but not in Rb(-/-) mouse embryo fibroblasts. Dephosphorylation of RB in S-phase cells temporally preceded the inhibition of DNA synthesis. This S-phase dephosphorylation of RB and subsequent inhibition of DNA replication was observed in p21(Cip1)-deficient cells. The induction of the RB-dependent intra-S-phase arrest persisted for days and correlated with a protection against DNA damage-induced cell death. These results demonstrate that RB plays a protective role in response to genotoxic stress by inhibiting cell cycle progression in G(1) and in S phase.

BRG-1 is required for RB-mediated cell cycle arrest

The antiproliferative action of the retinoblastoma tumor suppressor protein, RB, is disrupted in the majority of human cancers. Disruption of RB activity occurs through several disparate mechanisms, including viral oncoprotein binding, deregulated RB phosphorylation, and mutation of the RB gene. Here we report disruption of RB-signaling in tumor cells through loss of a critical cooperating factor. We have previously reported that C33A cells fail to undergo cell cycle inhibition in the presence of constitutively active RB (PSM-RB). To determine how C33A cells evade RB-mediated arrest, cell fusion experiments were performed with RB-sensitive cells. The resulting fusions were arrested by PSM-RB, indicating that C33A cells lack a factor required for RB-mediated cell cycle inhibition. C33A cells are deficient in BRG-1, a SWI/SNF family member known to stimulate RB activity. Consistent with BRG-1 deficiency underlying resistance to RB-mediated arrest, we identified two other BRG-1-deficient cell lines (SW13 and PANC-1) and demonstrate that these tumor lines are also resistant to cell cycle inhibition by PSM-RB and p16ink4a, which activates endogenous RB. In cell lines lacking BRG-1, we noted a profound defect in RB-mediated repression of the cyclin A promoter. This deficiency in RB-mediated transcriptional repression and cell cycle inhibition was rescued through ectopic coexpression of BRG-1. We also demonstrate that 3T3-derived cells, which inducibly express a dominant-negative BRG-1, arrest by PSM-RB and p16ink4a in the absence of dominant-negative BRG-1 expression; however, cell cycle arrest was abrogated on induction of dominant-negative BRG-1. These findings demonstrate that BRG-1 loss renders cells resistant to RB-mediated cell cycle progression, and that disruption of RB signaling through loss of cooperating factors occurs in cancer cells.

Differential requirements for ras and the retinoblastoma tumor suppressor protein in the androgen dependence of prostatic adenocarcinoma cells

Prostate cells are dependent on androgen for proliferation, but during tumor progression prostate cancer cells achieve independence from the androgen requirement. We report that androgen withdrawal fails to inhibit cell cycle progression or influence the expression of cyclin-dependent kinase (CDK)/cyclins in androgen-independent prostate cancer cells, indicating that these cells signal for cell cycle progression in the absence of androgen. However, phosphorylation of the retinoblastoma tumor suppressor protein (RB) is still required for G1-S progression in androgen-independent cells, since the expression of constitutively active RB (PSM-RB) or p16ink4a caused cell cycle arrest and mimicked the effects of androgen withdrawal on downstream targets in androgen-dependent LNCaP cells. Since Ras is known to mediate mitogenic signaling to RB, we hypothesized that active V12Ras would induce androgen-independent cell cycle progression in LNCaP cells. Although V12Ras was able to stimulate ERK phosphorylation and induce cyclin D1 expression in the absence of androgen, it was not sufficient to promote androgen-independent cell cycle progression. Similarly, ectopic expression of CDK4/cyclin D1, which stimulated RB phosphorylation in the presence of androgen, was incapable of inactivating RB or driving cell cycle progression in the absence of androgen. We show that androgen regulates both CDK4/cyclin D1 and CDK2 complexes to inactivate RB and initiate cell cycle progression. Together, these data show that androgen independence is achieved via deregulation of the androgen to RB signal, and that this signal can only be partially initiated by the Ras pathway in androgen-dependent cells.

Cyclin A is a functional target of retinoblastoma tumor suppressor protein-mediated cell cycle arrest

Although RB inhibits the G(1)-S transition, the mechanism through which RB prevents cell cycle advancement remains unidentified. To delineate the mechanism(s) utilized by RB to exert its anti-proliferative activity, constitutively active RB proteins (which cannot be inactivated by phosphorylation) or p16ink4a (which prevents RB inactivation) were utilized. Both proteins inhibited the G(1)-S transition, whereas wild-type RB did not. We show that active RB acts to attenuate cyclin A promoter activity, and that overexpression of cyclin E reverses RB-mediated repression of the cyclin A promoter. Although cyclin A is an E2F-regulated gene, and it has been long hypothesized that RB mediates cell cycle advancement through binding to E2F and attenuating its transactivation potential, cyclin E does not reverse dominant negative E2F-mediated repression of the cyclin A promoter. Although active RB repressed both cyclin A and two other paradigm E2F-regulated promoters, only cyclin A transcription was restored upon co-expression of cyclin E. Additionally, we show that RB but not dominant negative E2F regulates the cyclin A promoter through the CCRE element. These data identify cyclin A as a downstream target of RB-mediated arrest. Consistent with this idea, ectopic expression of cyclin A reversed RB-mediated G(1) arrest. The findings presented suggest a pathway wherein cyclin A is a downstream target of RB, and cyclin E functions to antagonize this aspect of RB-mediated G(1)-S inhibition.

The retinoblastoma tumor suppressor inhibits cellular proliferation through two distinct mechanisms: inhibition of cell cycle progression and induction of cell death

Studies aimed at examining the precise function(s) of the retinoblastoma tumor suppressor protein, RB, have been hindered by the rapid phosphorylation and inactivation of ectopically expressed RB which occurs in the majority of cell types. Therefore, ectopically expressed RB is a poor inhibitor of cellular proliferation. We have designed constitutively active RB proteins, PSM-RB, that cannot be inactivated by phosphorylation. Using these proteins, we show that unlike wild-type RB, PSM-RB proteins inhibit cell cycle progression in a broad range of tumor cell types. Furthermore, unlike p16ink4a, PSM-RB is also a potent inhibitor of cell cycle progression in RB-deficient tumor cells. Surprisingly, we identified a tumor cell line that is resistant to the cell cycle inhibitory effects of PSM-RB. This finding challenges the hypothesis that RB must be inactivated in all cells for cell cycle progression to occur. Further characterization of this 'resistant' tumor line revealed that proliferation of these cells is still inhibited by PSM-RB. We show that this is due to PSM-RB-induced cell death. As such, these studies are the first to show that RB inhibits cellular proliferation through at least two distinct mechanisms - inhibition of cell cycle progression and induction of cell death.

D-type cyclins complex with the androgen receptor and inhibit its transcriptional transactivation ability

D-type cyclins regulate distinct cellular processes, such as mitotic cell cycle control, differentiation, and transcription. We have previously shown that the D-type cyclins are critical for the androgen-dependent proliferation of prostate cells. Here, we sought to determine whether cyclin D1 directly influences the transactivation potential of the androgen receptor, a transcription factor that strongly influences androgen-dependent proliferation. We found that ligand-mediated transcriptional activation of a physiological target, prostate-specific antigen, by the androgen receptor was inhibited by cyclins D1 and D3. The ability of D-type cyclins to inhibit androgen receptor transactivation was not shared with other cyclins, and cyclin D1 was as effective as dominant negative mutants of the androgen receptor in inhibiting transactivation. This function of cyclin D1 was independent of its role in cell cycle progression and is likely elicited through its ability to form a specific complex with the androgen receptor. These data underscore the various mechanisms through which the androgen receptor is regulated and also point to a negative feedback role for cyclin D1 in controlling androgen-dependent growth.

Speedy: a novel cell cycle regulator of the G2/M transition

Stage VI Xenopus oocytes are suspended at the G2/M transition of meiosis I, and represent an excellent system for the identification and examination of cell cycle regulatory proteins. Essential cell cycle regulators such as MAPK, cyclins and mos have the ability to induce oocyte maturation, causing the resumption of the cell cycle from its arrested state. We have identified the product of a novel Xenopus gene, Speedy or Spy1, which is able to induce rapid maturation of Xenopus oocytes, resulting in the induction of germinal vesicle breakdown (GVBD) and activation of M-phasepromoting factor (MPF). Spy1 activates the MAPK pathway in oocytes, and its ability to induce maturation is dependent upon this pathway. Spy1-induced maturation occurs much more rapidly than maturation induced by other cell cycle regulators including progesterone, mos or Ras, and does not require any of these proteins or hormones, indicating that Spy1-induced maturation proceeds through a novel regulatory pathway. In addition, we have shown that Spy1 physically interacts with cdk2, and prematurely activates cdk2 kinase activity. Spy1 therefore represents a novel cell cycle regulatory protein, inducing maturation through the activation of MAPK and MPF, and also leading to the premature activation of cdk2.

Multiple G1 regulatory elements control the androgen-dependent proliferation of prostatic carcinoma cells

Prostatic epithelial cells and most primary prostate tumors are dependent on androgen for growth, but how androgen regulates cellular proliferation remains unsolved. Using poorly understood mechanisms, recurrent tumor cells evade the androgen requirement. We utilized androgen-dependent prostatic tumor cells to demonstrate that androgen exerts its effect on the cell cycle by influencing specific aspects of G1-S progression. Androgen depletion of these cells results in early G1 arrest, characterized by reduced cyclin-dependent kinase activity, and underphosphorylated retinoblastoma tumor suppressor protein (RB). The reduction in kinase activity was partially attributed to reduction of specific G1 cyclins and alternate regulation of cyclin-dependent kinase inhibitors. Using this information, we developed a reliable assay to assess the ability of specific G1 regulatory proteins to circumvent these controls and promote androgen-independent growth. As expected, inactivation of RB was required for progression through the cell cycle. Surprisingly, overexpression of G1 cyclins, which drives RB phosphorylation, was insufficient to promote androgen-independent cell cycle progression. Introduction of viral oncoproteins did promote G1-S progression in the absence of androgen, dependent on their ability to sequester RB and related proteins. These results provide the first evidence that multiple elements governing the G1-S transition dictate androgen-dependent growth, and the formation of androgen-independent prostatic tumors may be because of misregulation of these processes.

Elevated cyclins and cyclin-dependent kinase activity in the rhabdomyosarcoma cell line RD

An important early event in the differentiation of skeletal muscle cells is exit from the cell cycle, after which full expression of the muscle phenotype occurs. Rhabdomyosarcoma (RMS), a tumor of skeletal muscle origin, expresses a number of muscle-specific proteins, including MyoD; however, these cells fail to arrest or differentiate when cultured in differentiation medium (DM). To determine the basis for the failure of RMS cells to differentiate or arrest, we studied the molecular response of the embryonal RMS cell line, RD, to culture in DM. Under these conditions, the retinoblastoma protein (RB) was primarily in the hyperphosphorylated state. This is in contrast to myoblasts cultured in DM, in which the hypophosphorylated form of RB is exclusively present. Measurements of the expression and activities of cyclin-dependent kinases (cdks) cdk2 and cdk4 indicated that RD cells maintained higher levels than do myoblasts, and the activity and abundance of these proteins did not significantly decrease upon culture in DM in RD cells, as they did in myoblasts. Similarly, elevated expression of cyclins D1, E, and A was observed in RD cells. Interestingly, cdk inhibitors are expressed in RD cells, with p16ink4 expression markedly elevated relative to myoblasts. Ectopic expression of p21cip1, p16ink4, or p27kip1 caused a growth arrest of RD cells but not detectable expression of a myogenic marker. Furthermore, a constitutively active RB protein could also inhibit the growth of RD cells without inducing myogenic differentiation. Taken together, these data suggest that the elevated levels of cdk2 and/or cdk4 observed in RD cells contribute to the inability of RD cells to growth arrest when cultured in DM but that these activities alone are not responsible for the failure of RD cells to differentiate.

Pneumopericardium associated with high-frequency jet ventilation during laser surgery of the hypopharynx in a child

A case of pneumopericardium, without concomitant pneumothorax, resulting from high frequency jet ventilation during laser surgery of the hypopharynx is described. The patient, a four-year-old boy, suffered cardiac arrest as a consequence of the incident. The pneumopericardium was likely to have been caused by obstruction to the expiratory flow during surgery. Other possible explanations for the incident are discussed.

Schistosoma japonicum and Trichuris suis infections in pigs fed diets with high and low protein

The aim of the study was to measure the impact of Schistosoma japonicum and Trichuris suis infections in young growing pigs fed low- or high-protein diets. Thirty-two pigs. 6-10 weeks old, were randomly allocated to 2 groups receiving either a high- or a low-protein diet. After 11 weeks half of the pigs from each group were infected with 1500 S. japonicum cercariae and 4000 T. suis eggs. The weight of the pigs was measured throughout the study, and blood and faecal samples were collected every second week from the time of infection. At the time of infection the low-protein pigs had significantly lower mean body weights, haemoglobin and albumin levels compared with the high-protein pigs, and this pattern continued throughout the study. The serum albumin concentration was further significantly reduced in the infected low-protein pigs compared to the non-infected low-protein pigs. Significantly more S. japonicum worms as well as faecal and tissue eggs were found in the low-protein pigs compared with the high-protein pigs. No differences between the 2 diet groups were observed in T. suis establishment rates or faecal egg excretion. We conclude that this low-protein diet increased the establishment rates of S. japonicum, favoured larger deposits of S. japonicum eggs in the liver and faecal egg excretion, reduced weight gains and caused anaemia and hypoalbuminaemia in young growing pigs as compared with a high-protein diet.

The impact of diets varying in carbohydrates resistant to endogenous enzymes and lignin on populations of Ascaris suum and Oesophagostomum dentatum in pigs

The impact of diets varying in type and level of carbohydrates resistant to endogenous enzymes and lignin on the establishment and location of Ascaris suum and Oesophagostomum dentatum was investigated experimentally. Fifty worm-free pigs, from a specific pathogen-free farm were used. The animals were assigned randomly to 5 diets and infected with 600 infective A. suum eggs and 6000 infective larvae of O. dentatum per pig. The diets consisted of a traditional ground barley plus protein feed (diet A), commercial full-constituent pelleted feed (diet B), barley flour plus protein (diet C), barley flour, inulin (Raftiline ST, ORAFTI, Tienen, Belgium), sugar beet fibre plus protein (diet D), and barley flour, wheat bran, and protein (diet E). The faecal egg excretion was followed and the pigs were slaughtered at 8 weeks p.i. and samples taken from the small and large intestine. Intestinal contents were analysed for worm burdens, worm location and female worm fecundity along with the concentration of insoluble (chromic oxide) and soluble (polyethylene glycol-4000) markers, lignin, non-starch polysaccharides (NSP) and organic acids. In all diet groups A. suum worm burdens were low and comparable, whereas the O. dentatum worm burdens were significantly higher in pigs fed the diets with high levels of NSP and lignin (diets A and E) than in pigs fed diets B, C, and D. The present study suggests that a diet rich in lignin and insoluble NSP's provides favourable conditions for the establishment of O. dentatum in the large intestine of pigs while it is unlikely that the concentration of short-chain fatty acids and pH plays and major role.

Transcriptional silencing of Ty1 elements in the RDN1 locus of yeast

We demonstrate that in Saccharomyces cerevisiae, the tandem array of ribosomal RNA genes (RDN1) is a target for integration of the Ty1 retrotransposon that results in silencing of Ty1 transcription and transposition. Ty1 elements transpose into random rDNA repeat units and are mitotically stable. In addition, we have found that mutation of several putative modifiers of RDN1 chromatin structure abolishes silencing of Ty1 elements in the rDNA array. Disruption of SIR2, which elevates recombination in RDN1, or TOP1, which increases psoralen accessibility in rDNA, or HTA1-HTB1, which reduces histone H2A-H2B levels and causes localized chromatin perturbations, abolishes transcriptional silencing of Ty1 elements in RDN1. Furthermore, deletion of the gene for the ubiquitin conjugating enzyme Ubc2p, which ubiquitinates histones in vitro, derepresses not only Ty1 transcription but also mitotic recombination in RDN1. On the basis of these results, we propose that a specialized chromatin structure exists in RDN1 that silences transcription of the Ty1 retrotransposon.

Ondansetron reduces nausea and vomiting after paediatric adenotonsillectomy

The efficacy, safety and resource implications of a single intravenous dose of ondansetron (0.1 mg.kg-1, maximum 4 mg) were assessed in a multinational, multicentre, randomized, double-blind, placebo-controlled trial of 427 children aged 1-12 years, undergoing tonsillectomy with/without adenoidectomy. Emesis (retching and/or vomiting) and nausea were analysed separately. Significantly more ondansetron-treated children had no episodes of emesis (127/212 (60%) vs 100/215 (47%); P = 0.004) and experienced no postoperative nausea (135/211 (64%) vs 108/213 (51%); P = 0.004) in the first 24 h. Ondansetron also reduced the number of emetic episodes (P < 0.001), the time to the first emetic episode (P < 0.001) and overall nausea severity (P = 0.003). Significantly fewer ondansetron-treated children were rescued or withdrawn from the study (5% vs 10%; P = 0.042). Fewer ondansetron-treated patients required nursing intervention (34% vs 45%; P = 0.007) and the average intervention time was significantly shorter (4.6 vs 8.1 minutes; P = 0.001). Resources used to manage PONV were significantly reduced by ondansetron (43% vs 57%; P = 0.014).

Comparison of tenoxicam by intramuscular injection or wound infiltration for analgesia after inguinal herniorrhaphy

We compared wound infiltration with small-dose tenoxicam (7.5 mg) to intramuscular (IM) administration of the same dose to treat pain after herniorrhaphy. In a randomized, double-blind study, 50 patients received either preoperative wound infiltration with tenoxicam, 7.5 mg in 40 mL of 0.9% saline (WI group; n = 25) or IM tenoxicam 7.5 mg (IM group; n = 25). In each group a saline placebo of equal volume was given by the alternate route, i.e., those who received wound infiltration with tenoxicam received 0.75 mL of 0.9% saline IM; those who received IM tenoxicam received 40 mL of 0.9% saline for wound infiltration. Postoperative pain was assessed with a verbal pain scale and a visual analog scale (VAS) at rest and during movement and cough, 1, 2, 4, 6, and 24 h postoperatively. Wound tenderness was assessed with an electronic algometer preoperatively, and 2, 4, and 6 h postoperatively. The need for supplementary analgesics (acetaminophen and morphine) was registered. No differences were observed between groups in VAS pain scores, verbal rating pain scores, pain pressure thresholds, or in need for supplementary analgesics. We conclude that tenoxicam 7.5 mg has no local analgesic effect on postoperative pain after herniorrhaphy.

p34cdc2 kinase activity is maintained upon activation of the replication checkpoint in Schizosaccharomyces pombe

All eukaryotes use feedback controls to order and coordinate cell cycle events. In Schizosaccharomyces pombe, several classes of checkpoint genes serve to ensure that DNA replication is complete and free of error before the onset of mitosis. Wild-type cells normally arrest upon inhibition of DNA synthesis or in response to DNA damage, although the exact mechanisms controlling this arrest are unclear. Genetic evidence in fission yeast suggests that the dependence of mitosis upon completion of DNA replication is linked to the regulation of the p34cdc2 cyclin-dependent kinase. It has been hypothesized that inhibition of DNA synthesis triggers down-regulation of p34cdc2 kinase activity, although this has never been shown biochemically. We analyzed the activity of p34cdc2 in wild-type and checkpoint-defective cells treated with a DNA synthesis inhibitor. Using standard in vitro assays we demonstrate that p34cdc2 kinase activity is maintained in wild-type cells arrested at the replication checkpoint. We also used a novel in vivo assay for p34cdc2 kinase activity, in which we expressed a fragment of the human retinoblastoma tumor suppressor protein in fission yeast. Phosphorylation of this fragment of the human retinoblastoma tumor suppressor protein is dependent on p34cdc2 kinase activity, and this activity is also maintained in cells arrested at the replication checkpoint. These data suggest that the mechanism for cell-cycle arrest in response to incomplete DNA synthesis is not dependent on the attenuation of p34cdc2 activity.

Intake of rye bread ileostomists increases ileal excretion of fiber polysaccharide components and organic acids but does not increase plasma or urine lignans and isoflavonoids

The excretion of starch, enzyme-resistant starch, dietary fiber components and organic acids (short-chain fatty acids plus lactic acid) as well as plasma and urine lignans and isoflavonoids was studied in eight ileostomists consuming mixed diets with wheat bread (low fiber diet) or rye bread (high fiber diet) in a crossover design. Average ileal excretions of enzyme-available starch were 3.5 g/d during the low fiber period and 4.1 g/d during the high fiber period. The excretion of enzyme-resistant starch was approximately the same (2.3 g/d) in both periods. In comparison with intake, similar amounts of total fiber residues were excreted both by subjects receiving the low fiber diet (3.4 g/d) and by those receiving the high fiber diet (2.7 g/d). However, subjects excreted significantly more of certain polysaccharide residues (fucose, galactose, and uronic acids) than they ingested. On average, the excretion of organic acids was 18.6 mmol/d during the low fiber period and 30.2 mmol/d during the high fiber period. No significant differences in plasma lignans were observed between the high fiber and the low fiber dietary periods. The present findings indicate that enzyme-available starch is highly digested and that a microbial breakdown of dietary fibers and probably other carbohydrates occurs in the small intestine. However, the bacterial activity in the ileostomists was not sufficient to cause an increased level in plasma lignans even when subjects consumed the high fiber rye diet.

The influence of dietary fibre source and level on the development of the gastrointestinal tract, digestibility and energy metabolism in broiler chickens

The present study was undertaken to provide detailed information about the effect of fibre source (pea fibre, wheat bran or oat bran) at inclusion levels of 0, 187 and 375 g/kg diet on the development of the digestive tract, nutrient digestibility and energy and protein metabolism in broiler chickens. Heat production was measured using open-air-circuit respiration chambers. Diets with increasing levels of pea fibre decreased the DM in droppings and increased excreta output (2.5-fold) relative to DM intake. Adaptation to increased dietary fibre levels included increases in the size of the digestive system, with pea fibre exerting a stronger impact than wheat bran or oat bran. The length of the intestine, and particularly the length and weight of the caecum, increased with the fibre level. The digestibility of all nutrients also decreased with increasing fibre level. The decrease in the digestibility in relation to NSP for the three fibre sources was bigger for oat bran (0.0020 per g dietary NSP) than for pea fibre and wheat bran (0.0014 and 0.0016 per g dietary NSP) indicating that the cell walls in oat bran (aleurone and subaleurone) had a significant negative effect on the digestibility of cellular nutrients, i.e. protein and fat. The degradation of the NSP constituents was far lower in chickens than found in other animal species such as pigs and rats, thus supporting the view that chickens do not ferment fibre polymers to a great extent. Excretion of organic acids (mainly lactic acid and acetic acid) accounted for up to 2% of metabolizable energy (ME) intake with the highest excretion for the high-fibre diets. H2 excretion was related to the amount of NSP degraded and indicated higher microbial fermentation with increasing fibre levels. The chickens' feed intake responded to a great extent to dietary ME concentration but expressed in terms of metabolic body size (W0.75) ME intake was depressed at the high fibre levels. Dietary NSP was able to explain between 86% (oat bran) and 96% (pea fibre) of the variation in ME concentration. The amount of energy available from fermentation of NSP appears to reach a maximum of 42 kJ/d independent of fibre source and level. Expressed in relation to ME intake the NSP fermentation contributed 3-4%. With increasing fibre intake the partitioning of retained energy between body protein and body fat changed in favour of protein.

Effects of varying content of soluble dietary fibre from wheat flour and oat milling fractions on gastric emptying in pigs

Four pigs fitted with a gastric cannula were fed on a wheat-flour-based diet (WF) and three oat-based diets, consisting mainly of oat flour (OF), rolled oats (RO) or oat bran (OB), for 1 week each. The stomach contents were collected quantitatively daily at 0.5, 1, 2, 3 or 5 h after feeding. The viscosity (mPa.s) of the liquid fraction of stomach contents 1 h after feeding was 1.7 with diet WF, 15 with diet OF, 30 with diet RO and approximately 400 with diet OB. The viscosity and the concentration of beta-glucan in the liquid phase was to some extent determined by the dietary level of beta-glucan in the diet. However, there was a trend towards a lower viscosity after longer exposure to the gastric juices. The correlation between logarithmic values for viscosity and concentration of beta-glucan in the liquid phase of digesta was r 0.45. On centrifugation of digesta there was a higher proportion present in the sediment phase when the pigs were fed on diets with a higher content of soluble dietary fibre (DF), suggesting that the digesta was more coherent. This possibility was supported by the higher water-holding capacity (WHC) of the sediment. Feeding diets with oats containing a higher soluble DF content led to lower recoveries of digesta, PEG 4000 (liquid-phase marker), and the DF components beta-glucan and arabinoxylan in the first hour after feeding. No effect related to the DF content of the diet was seen in the gastric emptying of starch and Cr2O3 (solid-phase marker). In conclusion, soluble DF from oats increased the viscosity of stomach contents and increased the ability of the dry matter to retain water. Higher levels of soluble DF led to higher recoveries of digesta, the liquid phase and DF itself in the initial stage of gastric emptying, whereas no effect was seen on the gastric emptying of starch.

Separation of phenotypes in mutant alleles of the Schizosaccharomyces pombe cell-cycle checkpoint gene rad1+

The Schizosaccharomyces pombe rad1+ gene is involved in the G2 DNA damage cell-cycle checkpoint and in coupling mitosis to completed DNA replication. It is also required for viability when the cdc17 (DNA ligase) or wee1 proteins are inactivated. We have introduced mutations into the coding regions of rad1+ by site-directed mutagenesis. The effects of these mutations on the DNA damage and DNA replication checkpoints have been analyzed, as well as their associated phenotypes in a cdc17-K42 or a wee1-50 background. For all alleles, the resistance to radiation or hydroxyurea correlates well with the degree of functioning of checkpoint pathways activated by these treatments. One mutation, rad1-S3, completely abolishes the DNA replication checkpoint while partially retaining the DNA damage checkpoint. As single mutants, the rad1-S1, rad1-S2, rad1-S5, and rad1-S6 alleles have a wild-type phenotype with respect to radiation sensitivity and checkpoint functions; however, like the rad1 null allele, the rad1-S1 and rad1-S2 alleles exhibit synthetic lethality at the restrictive temperature with the cdc17-K42 or the wee1-50 mutation. The rad1-S5 and rad1-S6 alleles allow growth at higher temperatures in a cdc17-K42 or wee1-50 background than does wild-type rad1+, and thus behave like "superalleles." In most cases both chromosomal and multi-copy episomal mutant alleles have been investigated, and the agreement between these two states is very good. We provide evidence that the functions of rad1 can be dissociated into three groups by specific mutations. Models for the action of these rad1 alleles are discussed. In addition, a putative negative regulatory domain of rad1 is identified.

Peritonsillar infiltration with low-dose tenoxicam after tonsillectomy

We have compared the effect of peritonsillar infiltration with tenoxicam 5 mg and placebo on postoperative pain after tonsillectomy. Fifty patients undergoing bilateral elective tonsillectomy under general anaesthesia were allocated randomly to receive peritonsillar infiltration with tenoxicam 5 mg in 8 ml of normal saline (4 ml per tonsil) or normal saline only, before tracheal extubation. Median time to first request for morphine (30 min in each group, P = 0.83), cumulative morphine requirements from 0 to 2 h after surgery (two and one doses, P = 0.50), and from 2 to 24 h after surgery (one dose in each group, P = 0.17) were similar. There were no significant differences between groups in VAS scores at rest or when drinking 100 ml of water at any time. The power of detecting a reduction in VAS scores of 20 mm was 90% at the 5% significance level.

Effects of reducing the starch content in oat-based diets with cellulose on jejunal flow and absorption of glucose over an isolated loop of jejunum in pigs

Four pigs fitted with two sets of re-entrant cannulas in the upper jejunum were used to study the effect of two oat-flour (F)- and oat-bran (B)-based diets without or with (FC and BC respectively) addition of 148 g wood cellulose/kg on jejunal flow and absorption of glucose over an isolated loop of jejunum. Mean transit time (MTT) of flow from the proximal re-entrant cannula increased from approximately 1.5 h with diet F to 2 h when feeding diet BC. Both the replacement of oat flour by oat bran and the supplementation of the diets with cellulose led to a significantly longer MTT for dry matter and the carbohydrates, except that cellulose did not have a significant effect on the mTT for the total non-starch polysaccharides. Only the addition of cellulose significantly delayed gastric emptying of the added liquid-phase (Polyethylene glycol 4000) and solid-phase (Cr2O3) markers, whereas no effect of the oat source used was seen. Feeding diets with a higher level of dietary fibre (DF) and lower content of starch, obtained by substitution with cellulose or by feeding oat bran instead of oat flour, reduced the recovery of starch from an isolated loop of jejunum. Consequently, the quantitative absorption of starch was not significantly different between diets when starch was related to the recovery of external markers. However, when related to the recovery of arabinoxylan (AX) there was a significantly lower absorption of starch from the bran-based diets in comparison with the flour-based diets. The capacity to digest and absorb the large quantities of starch entering the duodenum after a carbohydrate-rich meal appears to be the limiting factor for absorption in the upper jejunum. Therefore, any effect of DF on the rate of absorption of glucose is presumably an effect on gastric emptying rather than displacement of the site of starch absorption in the small intestine.

Digestion of polysaccharides and other major components in the small and large intestine of pigs fed on diets consisting of oat fractions rich in beta-D-glucan

The digestibility of polysaccharides and other major components and the metabolic response of the microflora in the small and large intestines to oat diets varying in mixed linked beta(1-->3; 1-->4)-D-glucan (beta-glucan) were studied in experiments with ileum-cannulated pigs. The oat fractions for diets were prepared in a dry milling process in which oat groats were milled into two endosperm fractions (oat flour 1 and oat flour 2) and oat bran. The digestibility of polysaccharides and the metabolic response of the microflora were followed for the two contrasting diets, oat flour 1 and oat bran, from ingestion to excretion while the digestibility of oat groats and oat flour 2 were estimated only at the ileum and in faeces. There was no degradation of beta-glucan from either oat flour 1 or bran in the stomach and the first, middle and distal thirds of the small intestine (average digestibility approximately 0), while in the terminal ileum digestibility increased to 0.30 to 0.17 respectively. The digestion of starch in the first third of the small intestine was lower for the high-beta-glucan oat-bran diet (0.49) than for the low-beta-glucan flour diet (0.64). However, digestibility differences between the two diets levelled out as the digesta moved aborally in the small intestine and the digestibility at the terminal ileum was almost complete (0.970-0.995) for all diets. Oat non-starch polysaccharides (NSP) were an easily digestible energy source for the microflora in the large intestine less than 13% of dietary NSP being recovered in faeces. The bulk of beta-glucan which survived the small intestine was degraded in the caecum and proximal colon while arabinoxylan was more slowly degraded. The amount of residues passing the ileo-caecal junction has little impact on the density of micro-organisms in the large intestine, which on the flour and bran diets were in the range of 10(10)-10(11) viable counts/g digesta, but a high impact on the activity of the flora in colon. Oat bran resulted in a higher proportion of butyric acid in large intestinal content compared with the flour diet. The faecal bulking effect of oat bran was mainly caused by an increased excretion of protein and fat, presumably of bacterial origin. Of all the diets tested the oat-bran diets had the lowest digestibilities of protein and fat at the terminal ileum and in the faeces.

Oat bran but not a beta-glucan-enriched oat fraction enhances butyrate production in the large intestine of pigs

Digestibility of polysaccharides and other macronutrients and the metabolic response of the microflora in the large intestine to a low dietary fiber wheat flour diet and three enriched diets with equal amounts of added dietary fiber (oat bran, a beta-glucan-enriched oat fraction and insoluble oat residues) were studied in ileal-cannulated pigs. The digestibility of starch was high in the small intestine (98-100%). At this site of the gastrointestinal tract there was also a significant degradation of mixed linked beta (1 --> 3; 1 --> 4)-D-glucan (beta-glucan) (45-54%), whereas arabinoxylan was quantitatively recovered in ileal effluent. Type and amount of polysaccharides passing the ileal-cecal junction had little effect of the density of microorganism in the large intestine (approximately 10(10) viable counts/g digesta) but did have a high impact on the activity of the flora in colon as measured by the concentration of ATP in digesta. The relative proportion of butyrate in the short-chain fatty acids in the luminal contents of the large intestine was 6.6-8.4% when the low dietary fiber wheat flour diet was fed. However, when either oat bran or insoluble residues were included in the diet, the level was raised to 9.3-11.2%. No effect was seen after the addition of the beta-glucan-enriched fraction. This study showed that arabinoxylan and not beta-glucan in the cell walls of oat bran was responsible for the enhanced butyrate production of oat bran.

[Evaluation of trainee assistant education]

All of the trainee assistant appointments in general practice in Denmark were assessed by means of a questionnaire investigation during a period of two years. Particular attention was paid to the quality of training and whether there were particular characteristics in the practice which provide the best training. The material consists of 360 questionnaires sent to trainee assistants in general practice one month before conclusion of the appointment. The percentage of replies was 89. The average number of years after graduation was 6.5, which is considerably higher than aimed at in future plans. The investigation reveals that the educational quality and training by the tutor did not appear to be influenced by the number of postgraduate years although there was no doubt that younger trainees required more training and supervision. The quality of training is best in one-man practices and this is followed closely by small partnerships. The investigation reveals that training by the tutor is of decisive significance. It is therefore recommended that trainees in general practice should be more closely associated with one of the practitioners responsible for training. Three fourths of the trainees found that trainee assistant appointment was better than hospital appointments in general. The investigation indicates that following should be standard in every practice: 1) own consultation room, 2) typed records, 3) an introductory leaflet and that training should be arranged with: 1) introduction, 2) half-way assessments, 3) daily conferences about individual patients and 4) weekly conferences about particular subjects related to the practice.

Gastrointestinal implications in the rat of wheat bran, oat bran and pea fibre

The gastrointestinal (GI) effects of three different dietary fibre (DF) sources: wheat bran (WB), oat bran (OB) and pea fibre (PF), were compared with a low-fibre diet in a 4-week trial with rats (initial bodyweight 210 g). The DF sources varied widely in chemical composition, solubility and water-holding properties, and particle size. The DF sources were mixed into diets to comprise the same amount of non-starch polysaccharides (NSP; 135 g/kg dry matter (DM)). Compared with the control diet, all fibre-containing diets reduced apparent digestibility of DM, energy, and protein significantly but to different extents. The ranking order of faecal DM bulking followed that of NSP recovery in the faeces: WB > OB > PF > control. The elongating effect of the diets on the GI tract was most pronounced in the rats fed on the OB diet. The mean transit time (MTT) of the OB diet was similar to that of the control diet (approximately 37 h), which was significantly slower than the MTT of the WB and PF diets (approximately 23 h). The study confirms that no simple cause and effect relationship exists between chemical composition, physical properties, and physiological effects of dietary fibre and their effects along the GI tract.

Nutrient digestibilities in ingredients fed alone or in combinations

Digestibility coefficients (DC) of protein, dry matter, energy, starch, and dietary fibre in individual feedstuffs were used to predict the DC in feed mixtures. Digestibility studies with growing rats involved six feed sources: soya-bean meal, barley, rapeseed meal, peas, wheat bran and wheat, given individually and in various combinations, i.e. fourteen diets in total. True digestibility of protein (TD) and apparent digestibility of starch could be predicted in feed mixtures from their respective DC values for the individual ingredients, except in the diet composed of peas + barley. Dry matter (DM) and insoluble dietary fibre digestibilities in the mixtures could also be calculated from their individual DC values. Energy digestibility could be predicted in all mixtures except for barley + wheat and peas + wheat. Although the discrepancies were significant, the differences were not great. The digestibility of soluble dietary fibre in the mixtures could be predicted as for the individual ingredients in all but three diets: rapeseed meal + barley, peas + barley and peas + wheat. The results confirm that DC values for TD, DM, energy, starch and dietary fibre in mixtures can be calculated with high precision from DC determined from individual ingredients. Caution should be taken though when mixtures contain a high amount of dietary fibre, especially of the soluble type.

[Pre-hospital care]

Organisatory and therapeutic characteristics for selected pre-hospital medical treatment systems are described. It is emphasized that all of the links in the therapeutic chain must function optimally to achieve effective treatment of acute disease and injuries. The importance of rapid decision-making by highly qualified medical staff is emphasized. On the basis of experience from Denmark and from abroad, a model for up-to-date pre-hospital treatment in Denmark is outlined.

Cancer incidence among workers in the Norwegian ferroalloy industry

The total mortality and the incidence of cancer was studied among a cohort of employees at the six oldest ferrosilicon and ferromanganese plants in Norway. The cohort consisted of 6494 men employed for more than 18 months before 1970 and has been followed up from 1953 to 1982. The standardised incidence ratio (SIR) for cancer (all sites) was 0.94. The observed number of cancers was as expected for lung cancer (SIR = 0.99) and for most of the other cancer sites studied. A statistically significant reduction of stomach cancer was found (SIR = 0.72). There was an increased incidence of lung cancer (SIR = 1.75) and cancer of the prostate (SIR = 1.56) in the workers at one ferrosilicon plant and of colonic cancer (SIR = 1.90) at another ferrosilicon plant.

The effect of provision of the first-limiting amino acid, gastrointestinal microbial activity and the level of nitrogen intake on protein utilization and energy digestibility in rats

1. The present work with growing rats was undertaken to study the effect of protein quality, gastrointestinal microbial activity and the level of nitrogen intake on protein utilization and energy digestibility. The experiment involved a total of thirty-six dietary treatments in a 9 x 4 factorial design, with five rats per treatment. The thirty-six diets resulted from nine protein sources. Each diet was composed of a basal N-free mixture plus minerals and vitamins, with N sources added at the expense of the N-free mixture to provide 15.0 gN/kg dry matter (DM) in the first three protein-addition treatments and 30.0 gN/kg DM in the fourth protein-addition treatment. The nine protein sources were soya-bean meal, casein, wheat gluten, skim-milk powder, meat-and-bone meal, wheat bran, barley, wheat and cooked brown beans (Phaseolus vulgaris). The four formulations for each protein source incorporated the protein unsupplemented at 15.0 gN/kg DM, unsupplemented at 30.0 gN/kg DM, or supplemented at 15.0 gN/kg DM with the estimated first-limiting amino acid or the antibiotic Nebacitin. 2. With all protein sources, the inclusion of the first-limiting amino acid had no effect on either protein or energy digestibility. 3. The microbial activity in the digestive tract affected protein utilization and energy digestibility to a different degree depending primarily on the level and type of dietary fibre. True protein digestibility (TD) of skim-milk powder and brown beans, both rich in easily-fermentable energy, increased from 0.959 to 1.000 and from 0.680 to 0.777 respectively by the addition of Nebacitin. TD of the other protein sources was only marginally affected by the antibiotic treatment. Only with brown beans was the biological value (BV) markedly affected by Nebacitin with an increase from 0.482 to 0.557 by the treatment. Energy digestibility was significantly lower in rats given antibiotic with soya-bean meal, wheat bran, barley, wheat and brown beans. 4. The effect of level of N intake on protein utilization was dependent on both protein quality and the fibre concentration of the diet. Protein sources with high BV were more affected than proteins of lower BV. It was concluded that TD is not always independent of dietary protein concentration.