A bedform phase diagram for dense granular currents.

Pyroclastic density currents (PDCs) are a life-threatening volcanic hazard. Our understanding and hazard assessments of these flows rely on interpretations of their deposits. The occurrence of stratified layers, cross-stratification, and bedforms in these deposits has been assumed as indicative of dilute, turbulent, supercritical flows causing traction-dominated deposition. Here we show, through analogue experiments, that a variety of bedforms can be produced by denser, aerated, granular currents, including backset bedforms that are formed in waning flows by an upstream-propagating granular bore. We are able to, for the first time, define phase fields for the formation of bedforms in PDC deposits. We examine how our findings impact the understanding of bedform features in outcrop, using the example of the Pozzolane Rosse ignimbrite of the Colli Albani volcano, Italy, and thus highlight that interpretations of the formative mechanisms of these features observed in the field must be reconsidered.

The hepatic soluble guanylyl cyclase-cyclic guanosine monophosphate pathway mediates the protection of remote ischemic preconditioning on the microcirculation in liver ischemia-reperfusion injury.

BACKGROUND: Remote ischemic preconditioning (RIPC) protects against liver ischemia reperfusion (IR) injury. An essential circulating mediator of this protection is nitric oxide (NO) induced by lower limb RIPC. One of the mechanisms through which NO generally acts is the soluble guanylyl cyclase-cyclic GMP (sGC-cGMP) pathway. The present study aimed to assess the role of hepatic sGC-cGMP in lower limb RIPC-induced protection against liver IR injury. METHODS: Mice were allocated to 4 groups: 1.Sham; 2.IR: 40 min of lobar hepatic ischemia and 2 hr reperfusion; 3.RIPC+IR: 6 cycles of 4x4 min IR of the lower limb followed by IR group procedure; (4) 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ)+RIPC+IR: ODQ (sGC inhibitor) was administered followed by RIPC+IR group procedure. Hepatic microcirculatory blood flow (MBF) was measured throughout the experiment. Plasma transaminases, hepatic histopathological and transmission electron microscopy studies were performed at the end of the experiment. Hepatic cGMP levels were measured in groups 1-3 in addition to an RIPC alone group. RESULTS: Compared to liver IR alone, RIPC+IR increased hepatic MBF during liver reperfusion (P<0.05), and reduced plasma transaminases (P<0.05) and ultrastructural markers of injury. In contrast compared to RIPC+IR, ODQ+RIPC+IR decreased hepatic MBF (P<0.05) and ultrastructural markers of injury. However, plasma transaminases were not significantly different in the ODQ+RIPC+IR compared to the RIPC+IR group. Hepatic cGMP levels were significantly elevated in the RIPC compared to sham group. CONCLUSIONS: The hepatic sGC-cGMP pathway is required for mediating the protective effects of lower limb RIPC on hepatic MBF in liver IR injury.

Role of endothelial nitric oxide synthase in remote ischemic preconditioning of the mouse liver.

Hindlimb remote ischemic preconditioning (RIPC) reduces liver ischemia/reperfusion (IR) injury in wild-type mice. The underlying mechanisms of RIPC are currently unknown. In this study, we investigated the role of endothelial nitric oxide synthase (eNOS) in mediating the protective effects of RIPC. Endothelial nitric oxide synthase knockout (eNOS(-/-) ) mice were divided into 4 groups: (1) a sham surgery group, (2) an RIPC group (6 cycles of 4 minutes of hindlimb ischemia and 4 minutes of hindlimb reperfusion), (3) an IR group [40 minutes of lobar (70%) hepatic ischemia and 2 hours of reperfusion], and (4) an RIPC+IR group (RIPC followed by the IR group procedures). Plasma liver aminotransferases, hepatic histopathological injury scores, transmission electron microscopy studies, and hepatic microcirculatory blood flow (MBF) were assessed. eNOS protein expression was analyzed in the livers and hindlimb muscles of wild-type mice. Hindlimb RIPC did not protect against subsequent liver IR injury in eNOS(-/-) mice; this was demonstrated by the lack of reduction in the plasma aminotransferase levels, histopathological scores, or ultrastructural features of IR injury in the RIPC+IR group versus the IR group. Hepatic MBF did not recover during liver reperfusion in the RIPC+IR group versus the IR group. eNOS protein expression was similar among all wild-type groups. In conclusion, eNOS is essential for the protective effects of hindlimb RIPC on liver IR injury. eNOS exerts its protective effects through the preservation of hepatic MBF. At 2 hours of reperfusion, eNOS protection is likely due to the increased activation of eNOS rather than increased expression.

Nitric oxide is an essential mediator of the protective effects of remote ischaemic preconditioning in a mouse model of liver ischaemia/reperfusion injury.

NO (nitric oxide) may protect the liver from IR (ischaemia/reperfusion) injury. RIPC (remote ischaemic preconditioning) also protects against liver IR injury; however, the molecular mediator(s) of RIPC are currently unknown. The aim of the present study was to assess the role of NO in hindlimb RIPC-induced protection against liver IR injury. Mice were allocated to the following groups: sham group; RIPC group (six cycles of 4×4 min IR of hindlimb); IR group [40 min lobar (70%) hepatic ischaemia and 2-h reperfusion]; RIPC+IR group (RIPC followed by IR group procedures); and C-PTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt]+RIPC+IR group [C-PTIO (a direct NO scavenger) was administered, followed by the RIPC+IR group procedure]. Hepatic MBF (microcirculatory blood flow) was measured throughout the experiment. Circulating NOx (nitrite and nitrate) levels, plasma liver transaminases, hepatic histopathological and TEM (transmission electron microscopy) studies were performed at the end of the experiment. NOx concentrations were significantly elevated (P<0.05) in the RIPC and RIPC+IR groups. Compared with liver IR alone, RIPC+IR preserved hepatic MBF during liver reperfusion (P<0.05). In contrast, C-PTIO+RIPC+IR reduced MBF compared with RIPC+IR (P<0.05). RIPC+IR reduced plasma transaminases (P<0.05), and histopathological and ultrastructural features of injury compared with IR alone. The protective effects of RIPC+IR in reducing liver IR injury were abrogated in the group that received antecedent C-PTIO (C-PTIO+RIPC+IR). In conclusion, NO is an essential mediator of the protection afforded by hindlimb RIPC against liver IR injury. The mechanisms underlying this protection involve preservation of the sinusoidal structure and maintenance of blood flow through the hepatic microcirculation.

Effect of remote ischemic preconditioning on liver ischemia/reperfusion injury using a new mouse model.

Ischemic preconditioning of remote organs (RIPC) reduces liver ischemia/reperfusion (IR) injury in the rabbit and rat. Mice are the only species available with a large number of transgenic strains. This study describes development and validation of a mouse model of hindlimb RIPC that attenuates liver IR injury. Mice were allocated to 4 groups: (1) Sham surgery; (2) RIPC: 6 cycles of 4 × 4 minutes ischemia/reperfusion of hindlimb; (3) IR: 40 minutes lobar (70%) hepatic ischemia and 2 hours reperfusion; (4) RIPC+IR: RIPC followed by IR group procedures. Plasma liver aminotransferases and hepatic histopathological and transmission electron microscopy studies were performed at the end of the experiment. Hepatic microcirculatory blood flow was measured throughout the experiment. Postoperative complications and animal survival were evaluated. Hindlimb RIPC using a tourniquet resulted in limb paralysis. Hindlimb RIPC using direct clamping of the femoral vessels showed no side effects. Compared to liver IR alone, RIPC+IR reduced plasma aminotransferases (P < 0.05) and histopathological and ultrastructural features of injury. Hepatic microcirculatory blood flow was preserved in the RIPC+IR compared to IR group (P < 0.05). There was no mortality in any of the groups. By demonstrating a consistent improvement in these features of liver IR injury with antecedent hindlimb RIPC and by minimizing experimental confounding variables, we validated this mouse model. In conclusion, we describe a validated mouse model of hindlimb RIPC that reduces liver IR injury. With the availability of transgenic mice strains, this model should prove useful in unraveling the mechanisms of protection of hindlimb RIPC.

Emerging infectious disease leads to rapid population declines of common British birds.

Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period.

Impact of genetic counseling and DNA testing on individuals with colorectal cancer with a positive family history: a population-based study.

What is the impact of a genetic evaluation for colorectal cancer susceptibility? We previously reported a study of individuals diagnosed with colorectal cancer at 60 years of age or less in a five-county area of New York including Rochester. Subjects reporting at least one first- or second-degree relative with colorectal cancer were invited to receive genetic counseling and DNA testing. Of the 37 persons tested, we previously reported that 6 were found to have deleterious mutations in MSH2 or MLH1. A mutation has since been found in a seventh subject in another laboratory. To evaluate the impact of the testing experience, we followed-up on 36 of these 37 subjects at 3 and 12 months after communicating their DNA test result. We ascertained their knowledge of colon cancer, whether they told relatives their test result, their surveillance behavior, and their mental health. Three months after receiving their result, subjects knew more about colon cancer if they had more cancer of all types in their family (p = 0.02). At 12 months, they knew more if they had been found to have a mutation (p < 0.001), were younger when DNA tested (p < 0.01), or were younger when diagnosed with cancer (p < 0.03). All but 1 of those found to have an abnormality told relatives. Relatives of 3 subjects in whom a mutation had been found came to us to be tested themselves. At 12 months, surveillance for colon and endometrial cancer was more adherent if there were more total cancers in the family (p < 0.05) or if the testee were more worried about cancer (p < 0.05). Self-assessed mental health at 12 months was better for those who were married (p < 0.05). This study suggests that individuals undergoing a genetic evaluation for an inherited susceptibility to colorectal cancer pursue recommended surveillance and inform relatives of their result.

Cystic fibrosis newborn screening: a pilot study to maximize carrier screening.

Newborn screening for cystic fibrosis (CF) is expanding because early diagnosis has been shown to result in improved nutrition and growth. Most newborns identified by a mutation panel have a single detected mutation and require sweat testing to exclude an additional undetected mutation. The resulting identification of CF carrier newborns, although not the primary purpose of screening, has three potential benefits, (1) the detection of trait-trait couples, (2) presymptomatic testing of these couples' previously born children who may have undetected CF, and (3) a carrier parent alerting his/her extended family members to the chance of also being a CF carrier. Reaping each benefit requires genetic counseling of parents and their accepting carrier testing. The purpose of this study was to utilize the sweat testing visit to educate parents about the value of carrier testing for themselves and their blood relatives. We compared special care (genetic counseling after explaining the sweat test result and offering of parental DNA testing, all on the sweat test visit) versus standard care (sweat test result reported by phone to the parents the next day by the newborn's physician, ideally with the recommendation to arrange genetic counseling and parental carrier testing). In the first year of New York State CF screening, 64 newborns with one detected mutation were reported in the nine-county region that includes Rochester. Of these, parents of 39 agreed to participate in the study and to be randomized to special or standard care. Sixty-one parents completed both the initial and 1-year follow-up questionnaires (30 couples and one mother). Of the 61 parents, 23 had carrier testing after the birth of the baby. The frequency of such parental testing was significantly higher in the special care group (17/34 or 50%) than in the standard care group (6/27 or 22%) (p < 0.05). This is the first evidence from a randomized trial that genetic counseling and offering carrier testing to parents on the sweat test visit increases identification of carrier parents. Such identification detects trait-trait parents and facilitates carrier testing among relatives.

A case of fatal ephedra intake associated with lipofuscin accumulation, caspase activation and cleavage of myofibrillary proteins.

Ephedra, a herb reported to suppress appetite and stimulate the sympathetic nervous system as well as cardiac performance, has recently been related to several adverse events, including seizure, stroke, hypertension, myocardial infarction, and sudden death. Here, we describe the case of a 45-year-old woman who died of cardiovascular collapse while taking ephedra. Tissue analysis revealed non-specific degenerative alterations in the myocardium (lipofuscin accumulation, basophilic degeneration and vacuolation of myocytes, as well as myofibrillary loss), associated with myocyte apoptosis, caspase activation, and extensive cleavage of miofibrillary proteins alpha-actin, alpha-actinin, and cardiac troponin T. Healthcare professionals are therefore urged to warn their patients about the risk of serious adverse effects, which may follow ephedra intake.

Inherited susceptibility to colorectal cancer.

The principal Mendelian disorders predisposing to colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). FAP is due to mutations in the APC gene. HNPCC is due to a mutation in one of at least five mismatch repair genes. Identification of individuals with these conditions is important because colon cancer will occur in approximately 80% and onset is early. For FAP, protein truncation testing will identify the vast majority of mutations. For HNPCC, 80%-95% can be identified by microsatellite instability testing. A current U.S. study reports that 12% of consecutive colorectal cancers have high microsatellite instability and that, of this 12%, 25% have detectable mutations of MLH1, MSH2, or MSH6. Potential benefits of identification include improved compliance with recommended surveillance, early detection of polyps, reduction in cancer mortality, offering of testing to relatives, and reassurance for relatives found to be negative with attendant savings in the time and expense of surveillance.

Impact of genetic testing for breast-ovarian cancer susceptibility.

Previously, we have reported a clinical trial in which any woman in a defined geographic region who had a qualifying family history and who was referred by her physician or who was identified through a regional cancer registry was offered free genetic counseling, BRCA testing, and recommendations based on test results. Each family was represented by one affected and one unaffected person. Of the 87 families actually tested, 13 were found to have deleterious mutations. To assess the impact of the counseling and testing process, we contacted the tested individuals 1 month and 1 year after receiving the test result and those with an abnormal test result after 4 years. Index subjects, we found, differed significantly from relatives. Before coming for counseling, index subjects perceived both their general health and emotional health as worse than did their relatives. After counseling and testing, index subjects continue to worry more about breast cancer than do relatives. Affected subjects, we found, differed significantly from unaffected subjects. Before counseling, affected subjects knew more about breast cancer, perceived their general health as poorer, and reported greater adherence to recommended breast cancer surveillance than did unaffected subjects. After counseling and testing, affected subjects were less satisfied than unaffected subjects with having been tested. This study indicates that the group most prone to distress by cancer risk genetic counseling and testing is not the recruited relatives, nor even those affected with cancer, but rather the index patients themselves. The index patients, i.e., the ones who want the risk information most, appear to undergo the most stress in obtaining it.

Screening for an inherited susceptibility to colorectal cancer.

The principal Mendelian disorders predisposing to colorectal cancer are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). FAP is caused by mutations in the adenomatous polyposis coli (APC) gene. HNPCC is caused by a mutation in one of at least five mismatch repair genes. It is important to identify individuals with these conditions because colon cancer will occur in at least 80% and onset is earlier than in the general population. Potential benefits of identification include improved compliance with recommended surveillance, early detection of polyps, reduction in cancer mortality, and reassurance for relatives found to be negative with attendant savings in the time and expense of surveillance. For classic FAP, the large number of polyps readily identifies affected persons. For HNPCC, identification of individuals meriting DNA sequencing requires either recognition of a suspect family history or finding high microsatellite instability in a tumor. Individuals accepting the offer of genetic counseling and DNA testing often have more cancers in their family, are motivated to inform relatives, have a larger social network, and have more confidence in their coping ability. Individuals who decline are often concerned about their own or their family's emotional reaction or fear discrimination.

Inhibition of telomerase activity in human cancer cells by RNA interference.

Telomerase is an attractive molecular target toward which to direct cancer therapeutic agents because telomerase activity is present in most malignant cells but undetectable in most normal somatic cells. Short duplex RNA (short-interfering RNA or siRNA) has recently been shown to be an effective method for inhibiting the expression of a given gene in human cells. Accordingly, we evaluated the ability of siRNA to inhibit telomerase activity in human cancer cells. Human cancer cell lines were transfected with 21 nt double-stranded RNA homologous to either the catalytic subunit of telomerase (human telomerase reverse transcriptase) or to its template RNA [human telomerase RNA(hTR)]. Both types of agents reduced telomerase activity in a variety of human cancer cell lines representing both carcinomas and sarcomas. Inhibition was dose-dependent, although modest in degree and, as expected, transient in duration. Transfection of HeLa cells using a plasmid containing the hTR gene in both forward and reverse orientations, intended to create a duplex of the hTR transcripts endogenously, resulted in decreased telomerase activity, decreased telomerase RNA content, and decreased telomeric DNA content but no decrease in the untargeted human telomerase reverse transcriptase mRNA. Telomerase inhibition by siRNA is notable because telomerase is regarded as restricted to the nucleus, whereas RNA interference is commonly regarded as restricted to the cytoplasm.

ATP-dependent vesiculation in red cell membranes from different hereditary stomatocytosis variants.

The hereditary stomatocytoses are a group of dominant haemolytic anaemias that show two main features: invaginated, 'stomatocytic' morphology; and a membrane leak to the univalent cations Na and K. A patient with the most severe variant of these conditions was reported to show a defect in an in vitro process of ATP-dependent endocytic vesiculation (ADEV), which is found in normal red cells. We have examined this endocytosis process in 11 leaky red cell pedigrees available to us in the UK. ADEV in broken membranes was absent only in the two most severely affected, 'overhydrated' pedigrees studied, both of which showed a deficiency in the membrane raft protein, stomatin. The process was present, although typically diminished by about 10-20% compared with normal red cells, in all others. The cross-linker dimethyl adipimate (DMA), which could correct the cation leak in some of these patients, also corrected the ADEV defect in the same patients. In those patients in whom DMA had no effect on the ion leak, ADEV was not absent. In normal cells, this process of vesiculation was inhibited by inhibitors of membrane 'raft' function, by an antistomatin antibody and by vanadate and N-ethyl maleimide, but not by inhibitors of a number of kinases. These data highlight the heterogeneity of these conditions. A mechanism is discussed by which a defect in raft-based endocytosis could lead to the exaggerated surface exposure of an ion channel, which could then function constitutively, i.e. 'leak'.

Patient vs. physician as the target of educational outreach about screening for an inherited susceptibility to colorectal cancer.

Are patients identified from a cancer registry better educated directly or via their physician about screening for an inherited susceptibility for colorectal cancer? Of 974 patients diagnosed with colorectal cancer at < or = 60 years from 1987 to 1999 in a five-county area including Rochester, the physicians of 651 patients (67%) forwarded a cancer family history survey to their patient; 459 (71%) completed the survey. Of these 459, 167 (36%) reported having at least one first- or second-degree relative with colon cancer and were sent a set of questionnaires and a more detailed family cancer history form. Of the 167, a total of 101 (60%) continued to qualify by returning the questionnaires. These 101 qualifying patients were randomized to either the patient-education or physician-education group. Of the 101, a total of 47 (47%) came for a free genetic evaluation. Individuals were more likely to accept evaluation if they were parents (p = 0.001), had more cancers of all kinds in their families (p = 0.02), and had a larger social network (p = 0.04). Of the 47 counseled, 36 (77%) chose to have DNA testing at no cost. Of these 47, individuals were more likely to choose DNA testing if they had more cancers in the family (p = 0.04) and fewer symptoms of depression (p = 0.05). Of the 36 tested patients, 6 (20%) were found to have mutations. In summary, acceptance of genetic services was related to the magnitude of the threat (more cancers in the family), perceived ability to deal with the threat (perceived good health and a supportive network), and a desire to inform relatives (being a parent). The two approaches to educating patients, viz. direct patient education vs. education via their physician, did not significantly differ in terms of percentages of patients receiving counseling (42% vs. 51%, respectively) or the percentage choosing DNA testing (32% vs. 37%, respectively).