The concurrent emergence and causes of double volcanic hotspot tracks on the Pacific plate.

Mantle plumes are buoyant upwellings of hot rock that transport heat from Earth's core to its surface, generating anomalous regions of volcanism that are not directly associated with plate tectonic processes. The best-studied example is the Hawaiian-Emperor chain, but the emergence of two sub-parallel volcanic tracks along this chain, Loa and Kea, and the systematic geochemical differences between them have remained unexplained. Here we argue that the emergence of these tracks coincides with the appearance of other double volcanic tracks on the Pacific plate and a recent azimuthal change in the motion of the plate. We propose a three-part model that explains the evolution of Hawaiian double-track volcanism: first, mantle flow beneath the rapidly moving Pacific plate strongly tilts the Hawaiian plume and leads to lateral separation between high- and low-pressure melt source regions; second, the recent azimuthal change in Pacific plate motion exposes high- and low-pressure melt products as geographically distinct volcanoes, explaining the simultaneous emergence of double-track volcanism across the Pacific; and finally, secondary pyroxenite, which is formed as eclogite melt reacts with peridotite, dominates the low-pressure melt region beneath Loa-track volcanism, yielding the systematic geochemical differences observed between Loa- and Kea-type lavas. Our results imply that the formation of double-track volcanism is transitory and can be used to identify and place temporal bounds on plate-motion changes.

Chemotaxis and Motility of Spongospora subterranea Zoospores in Response to Potato Root Exudate Constituents and pH.

Spongospora subterranea f. sp. subterranea is an important pathogen of potato responsible for major losses in most potato growing regions of the world. Infection is initiated by biflagellated motile zoospores released from long-lived resting spores. Zoospore chemotaxis to the host plant root is widely believed to be stimulated by host root exudate compounds, although direct evidence is lacking. This study refined the traditional chemotaxis capillary assay, with which we provided the first empirical evidence of S. subterranea zoospore chemotaxis. Individual potato root exudate metabolites were either taxis neutral, inhibitory, or attractant to the zoospores. L-Glutamine was the strongest chemoattractant, while spermine was the most inhibitory. Zoospore motility and chemotaxis were constrained by strongly acidic or alkaline solutions of pH < 5.3 and >8.5, respectively. Beyond pH, ionic constituents of the test solution affected zoospore motility as Sorensen's phosphate buffer stalled zoospore motility, but HEPES buffer at the same concentration and pH had little or no negative motility effect. Zoospore motility, as characterized by several parameters, influenced chemotaxis. Among the parameters measured, total distance traveled was the best predictor of zoospore chemotaxis. The characterization of environmental and ecological effects on zoospore motility and chemotaxis highlights useful targets for S. subterranea disease control through manipulation of zoospore taxis or selection of host resistance traits.

Genetic and host-associated differentiation within Thrips tabaci Lindeman (Thysanoptera: Thripidae) and its links to Tomato spotted wilt virus-vector competence.

Of eight thelytokous populations of onion thrips (Thrips tabaci) collected from potato (three populations), onion (four) or Chrysanthemum (one) hosts from various regions of Australia, only those from potato were capable of transmitting Tomato spotted wilt virus (TSWV) in controlled transmission experiments. Genetic differentiation of seven of these eight populations, and nine others not tested for TSWV vector competence, was examined by comparison of the DNA sequences of mitochondrial cytochrome oxidase subunit 1 (COI) gene. All Australian populations of T. tabaci grouped within the European 'L2' clade of Brunner et al. (2004). Within this clade the seven populations from potato, the three from onion, and the four from other hosts (Chrysanthemum, Impatiens, lucerne, blackberry nightshade) clustered as three distinct sub-groupings characterised by source host. Geographical source of thrips populations had no influence on genetic diversity. These results link genetic differentiation of thelytokous T. tabaci to source host and to TSWV vector capacity for the first time.

Ten-year follow-up of skin-sparing mastectomy followed by immediate breast reconstruction.

BACKGROUND: The oncological safety of skin-sparing mastectomy (SSM) followed by immediate breast reconstruction (IBR) is debated owing to a presumed compromise in the completeness of mastectomy. Current evidence is poor as it is based mostly on short-term follow-up data from highly selected patients. METHODS: A prospectively maintained institutional database was searched to identify patients who underwent SSM and IBR between 1995 and 2000. A retrospective review of medical records was carried out, including only patients with ductal carcinoma in situ and invasive breast cancer. During this time all patients treated with mastectomy were offered IBR regardless of tumour stage. RESULTS: Follow-up data from 253 consecutive patients with IBR were reviewed. Patients with incomplete follow-up data and those undergoing SSM for recurrent disease following previous lumpectomy were disregarded, leaving 207 for analysis. Offering IBR to all women requiring mastectomy resulted in a large proportion of patients with advanced disease. During a median follow-up of 119 months, 17 (8·2 per cent) locoregional, six (2·9 per cent) local and 22 (10·6 per cent) distant recurrences were detected; the overall recurrence rate was 39 (18·8 per cent). Overall recurrence rate was associated with axillary lymph node metastasis (P = 0·009), higher stage (P < 0·001) and higher tumour grade (P = 0·031). The breast cancer-specific survival rate was 90·8 per cent (19 of 207 women died from recurrence). CONCLUSION: Based on these long-term follow-up data, SSM combined with IBR is an oncologically safe treatment option regardless of tumour stage.

Mammalian recombination-repair genes XRCC2 and XRCC3 promote correct chromosome segregation.

Growth and development are dependent on the faithful duplication of cells. Duplication requires accurate genome replication, the repair of any DNA damage, and the precise segregation of chromosomes at mitosis; molecular checkpoints ensure the proper progression and fidelity of each stage. Loss of any of these highly conserved functions may result in genetic instability and proneness to cancer. Here we show that highly significant increases in chromosome missegregation occur in cell lines lacking the RAD51-like genes XRCC2 and XRCC3. This increased missegregation is associated with fragmentation of the centrosome, a component of the mitotic spindle, and not with loss of the spindle checkpoint. Our results show that unresolved DNA damage triggers this instability, and that XRCC2 and XRCC3 are potential tumour-suppressor genes in mammals.

Impact of national guidelines on family history breast cancer surveillance.

The breast cancer risk of women already under family history surveillance was accurately assessed according to national guidelines in an attempt to rationalize the service. Women attending two breast units in Glasgow between November 2003 and February 2005 were included. One thousand and five women under annual surveillance were assessed and had their relatives diagnoses verified. Four hundred and ninety-seven women were at significantly increased risk and eligible for follow-up. Five hundred and eight (50%) women attending were not eligible for family history surveillance, and 498 (98%) of these women accepted discharge. In conclusion, national guidelines have helped to more clearly define women who should undergo surveillance. This avoids unnecessary and potentially harmful routine investigations, and the service has been improved.

Formalizing planning and information search in naturalistic decision-making.

Decisions made by mammals and birds are often temporally extended. They require planning and sampling of decision-relevant information. Our understanding of such decision-making remains in its infancy compared with simpler, forced-choice paradigms. However, recent advances in algorithms supporting planning and information search provide a lens through which we can explain neural and behavioral data in these tasks. We review these advances to obtain a clearer understanding for why planning and curiosity originated in certain species but not others; how activity in the medial temporal lobe, prefrontal and cingulate cortices may support these behaviors; and how planning and information search may complement each other as means to improve future action selection.

Addition of fornix transection to frontal-temporal disconnection increases the impairment in object-in-place memory in macaque monkeys.

Both frontal-inferotemporal disconnection and fornix transection (Fx) in the monkey impair object-in-place scene learning, a model of human episodic memory. If the contribution of the fornix to scene learning is via interaction with or modulation of frontal-temporal interaction--that is, if they form a unitary system--then Fx should have no further effect when added to frontal-temporal disconnection. However, if the contribution of the fornix is to some extent distinct, then fornix lesions may produce an additional deficit in scene learning beyond that caused by frontal-temporal disconnection. To distinguish between these possibilities, we trained three male rhesus monkeys on the object-in-place scene-learning task. We tested their learning on the task following frontal-temporal disconnection, achieved by crossed unilateral aspiration of the frontal cortex in one hemisphere and the inferotemporal cortex in the other, and again following the addition of Fx. The monkeys were significantly impaired in scene learning following frontal-temporal disconnection, and furthermore showed a significant increase in this impairment following the addition of Fx, from 32.8% error to 40.5% error (chance = 50%). The increased impairment following the addition of Fx provides evidence that the fornix and frontal-inferotemporal interaction make distinct contributions to episodic memory.

Biochemical evaluation of storage lesion in canine packed erythrocytes.

OBJECTIVES: To describe the biochemical changes - also known as the storage lesion - that occur in canine packed red blood cells during ex vivo storage. MATERIALS AND METHODS: Ten 125-mL units of non-leuco-reduced packed red blood cells in citrate phosphate dextrose adenine were obtained from a commercial blood bank within 24 hours of donation. Samples were aseptically collected on days 1, 4, 7, 14, 28, 35 and 42 for measurement of sodium, potassium, chloride, lactate, glucose, pH and ammonia concentrations. All units were cultured on day 42. Friedman's repeated measures test with Dunn's multiple comparison test was used for non-parametric data. A repeated-measures analysis of variance with Tukey's multiple comparison test was used for parametric data. Alpha was set to 0·05. RESULTS: All analytes changed significantly during storage. The mean ammonia on day 1 (58·14 g/dL) was significantly lower (P<0·05) than those on days 28 (1266 g/dL), 35 (1668 g/dL) and 42 (1860 g/dL). A significant increase in median lactate concentration over time was also observed, with day 1 (4·385 mmol/L) being significantly less (P<0·05) than days 14 (19·82 mmol/L), 21 (22·81 mmol/L), 35 (20·31 mmol/L) and 42 (20·81 mmol/L). Median pH was significantly decreased after day 7. All bacterial cultures were negative. CLINICAL SIGNIFICANCE: Many biochemical alterations occur in stored canine packed red blood cells, although further studies are required to determine their clinical importance.

Biochemical evaluation of the effects of storage on feline erythrocytes.

OBJECTIVE: To describe the biochemical changes that occur during storage of feline packed red blood cells. METHODS: Feline packed red blood cells were obtained from the manufacturer via overnight delivery immediately following collection. Bag spikes were placed using aseptic technique and samples were drawn on days 1, 4, 7, 14, 21, 28 and 35. Sodium, potassium, chloride, glucose, lactate, pH and ammonia were measured at each time point. Aerobic and anaerobic bacterial cultures were submitted following collection on day 35. RESULTS: There were statistically significant increases in the median concentrations of lactate and ammonia within the first 2 weeks of storage to a concentration of 12·38 mmol/L and 447·96 µmol/L, respectively. Glucose concentrations decreased significantly by day 28 to a mean of 1·86 mmol/L. Median sodium and chloride concentrations increased throughout the course of storage to a concentration of 158·20 and 131·00 mmol/L, respectively. Mean potassium concentrations decreased to a concentration of 2·40 mmol/L. CLINICAL SIGNIFICANCE: These results show that biochemical derangements within feline packed red blood cells are progressive, with some alterations, such as lactate and ammonia, occurring early within the storage periods, while others, including glucose and electrolytes, are slower to develop. Additional prospective research evaluating the clinical effects of these biochemical alterations is required.

Plasma leptin and insulin levels in weight-reduced obese women with normal body mass index: relationships with body composition and insulin.

Obesity is a complex disease with multiple features that has confounded efforts to unravel its pathophysiology. As a means of distinguishing primary from secondary characteristics, we compared levels of fasting plasma leptin and insulin in a cohort of weight-reduced obese women who have attained and maintained a normal BMI for more than 1 year with the levels in cohorts of never-obese and currently obese women. Weight-reduced obese women showed decreased plasma concentrations of leptin and insulin compared with obese women, but these levels remained significantly higher than those of never-obese women. Plasma leptin levels were highly correlated with plasma insulin levels (r = 0.60, P < 0.001). To further explore relationships with body composition, total body fat was determined by dual-energy X-ray absorptiometry and body fat distribution by computed tomography in subsets of these groups. Weight-reduced obese women had a significantly greater percent body fat and subcutaneous abdominal fat mass than did the never-obese women, and these were highly correlated with plasma leptin (r = 0.90, P < 0.001, and r = 0.52, P < 0.001, respectively). In these weight-reduced obese women, visceral fat mass was similar to that of the never-obese. The insulin sensitivity index and first-phase insulin response were also comparable. These results demonstrate that higher leptin levels in weight-reduced obese women are related to the higher total fat and particularly the subcutaneous fat masses. Normalization of visceral fat mass in the weight-reduced obese was accompanied by normalization of insulin sensitivity index and first-phase insulin response. This study suggests that increases in plasma leptin and insulin in obesity are secondary features of the obese state.

Relative contribution of obesity and body fat distribution to alterations in glucose insulin homeostasis: predictive values of selected indices in premenopausal women.

Obesity and fat topography are risk factors for hyperinsulinemia, insulin resistance, and diabetes mellitus. The relative contribution of obesity and body fat distribution indices to fasting and oral glucose-stimulated C peptide, insulin, and glucose concentrations were determined in 33 healthy premenopausal women. Obesity level was assessed by hydrostatic weighing and fat topography by computerized tomography-derived intraabdominal fat area, waist to hip ratio, subscapular skinfold thickness and the ratio of subscapular to triceps skinfold thickness. Both fat mass and regional fat distribution indices were associated closely with changes in insulin secretion. Fat topography indices were more closely correlated (p less than 0.001) to insulin response than were fat mass indices (p less than 0.01). The subscapular skinfold thickness had the greatest integrity for reflecting fat mass and fat distribution as they relate to the metabolic profile. The subscapular skinfold thickness may help identify individuals at risk for noninsulin dependent diabetes mellitus.

Iodine-131 contamination from thyroid cancer patients.

High-dose radioactive iodine therapy using 131I is the treatment of choice for patients with thyroid cancer following thyroidectomy. Because of the large amount of activity which is excreted during hospitalization, contamination hazard from 131I excretion via perspiration, saliva, breath and urine may arise. In eight patients treated with doses of 131I ranging from 3.7 to 14.8 GBq (100-400 mCi), activity levels were measured in room air, from room surfaces, the toilet, the patients' exhaled breath, skin, saliva and toothbrushes, and the gloves used by medical staff. Thyroid bioassays were also performed on medical staff personnel caring for these patients both before and two days after administration of the treatment dose. Removable activity from the skin was positively correlated with treatment dose and reached a maximum at 24 hr post-therapy. Removable activity from room surfaces exceeded the level of contamination which requires clean-up in a restricted area during the patient's hospitalization. Thyroid bioassays on medical staff showed no significant uptake 2 days after treatment. The relatively high activities present in the saliva, urine and on the skin of these patients emphasizes the need for all individuals coming in contact with these patients to be made aware of the contamination hazard present.

Apnea prolongation via short-term inhibition.

Central apneas during sleep are frequently of longer duration than predicted and persist despite high levels of chemical stimuli. We provide evidence that suggests that this apnea prolongation represents a central inertia in the control system mediated by reciprocal inhibition of inspiration.

Dichromatic absorptiometry of vertebral bone mineral content.

A dichromatic photon absorptiometric technique for the in vivo measurement of the bone mineral of the spine is discussed. A high purity, high activity 153Gd source which has photons of predominantly 44 and 100 keV was used as the transmission source. The transmission scans were performed on a modified Ohio Nuclear whole body rectillinear scanner. The precision of four measurements on three individuals and three measurements on one individual over a one month period was 2.3% (coefficient of variation). The accuracy determined by measurements of phantoms with known concentrations of dipotassium hydrogen phosphate solutions was 1.2% (standard error of estimate). This technique can be applied in most well equipped nuclear medicine departments.

The effect of varying high pass filter parameters on the detectability of isolated pulmonary nodules in digitized chest images.

The effect of image processing of digital radiographic data on lesion detectability in clinical images has not been systematically studied. In this experiment, we evaluated a low frequency suppression filter program applied to CT digital radiographic localization images (General Electric Scoutview). Three different filter parameters affecting edge enhancement and local image contrast were applied to a set of digital chest images. A standard observer detection experiment comparing the variously filtered digital images and standard chest radiographs in the detection of lung nodules (11 peripheral lung fields, one superimposed on aortic arch) was performed. Standard chest radiography was more sensitive than the digital chest images, although some improvement was noted with increase in local image contrast and edge enhancement. Both image formats were equally specific. Image processing would be better evaluated using a digital imaging system with better performance parameters.

Abdominal computed radiography: evaluation of low-constrast lesions.

Computed radiography has proved useful as a localization device for computed tomography. In an attempt to evaluate computed radiography as a primary diagnostic device, 16 patients were evaluated with various degrees of gallbladder opacification following standard oral cholecystograms, and 15 patients were evaluated with renal masses, identified on standard excretory urography. Subjective evaluation of computed radiographs as compared to the standard radiographs demonstrated no diagnostic advantage to computed radiography. The poor spatial resolution of the computed radiographs was not overcome by the improvement in contrast resolution.

Dietary microbial toxins and type 1 diabetes.

Toxins may promote type 1 diabetes by modifying or damaging the beta cell causing release of autoantigens. Streptomyces is a common soil bacterium that produces many toxic compounds. Some Streptomyces can infect vegetables, raising the possibility of dietary exposure to toxins. We aimed to identify toxins that erode cellular proton gradients in extracts of Streptomyces and infested vegetables and to establish the effect of low doses of these toxins on pancreatic islets in mice. The vacuolar ATPase inhibitors, bafilomycin and concanamycin, and the ionophore, nigericin, were identified in extracts from 4 of 13 Streptomyces isolated from infested potatoes and in potatoes themselves. Injection of bafilomycin A1 into mice impaired glucose tolerance, reduced islet size, and decreased relative beta cell mass. Thus, exposure to small quantities of bafilomycin in the diet may contribute to the cause of type 1 diabetes.

Elevated salivary cortisol in the evening in healthy elderly men and women: correlation with bone mineral density.

BACKGROUND: Aging is associated with a loss of bone mineral density (BMD) in men and women. Loss of BMD can also be caused by hypercortisolemia in men or women at any age. This study measured salivary cortisol at 2300 h and 0700 h as indices of cortisol secretory activity in 228 elderly, community-dwelling subjects. Salivary cortisol results were correlated with BMD. We hypothesized that salivary cortisol is elevated at 2300 h in elderly people, and that salivary cortisol will correlate negatively with BMD. METHODS: Saliva was sampled at 2300 h (nadir in circadian rhythm) and 0700 h (peak in circadian rhythm) in 130 men (70.7 +/- 0.4 years old) and 98 women (70.0 +/- 0.4 years old); approximately half of the women were receiving hormone replacement therapy (HRT). BMD was measured by dual energy x-ray absorptiometry. RESULTS: Salivary cortisol at 2300 h was significantly elevated in men (2.3 +/- 0.1 nmol/L) and women (2.1 +/- 0.1 nmol/L) as compared to 73 younger controls (1.2 +/- 0.1 nmol/L; 37 +/- 1 year old). Salivary cortisol at 0700 h was not different between older subjects and younger controls. There was a significant negative correlation of lumbar (L2-4) BMD and 2300 h salivary cortisol in older women (r = -0.20, p = .05; n = 98); this correlation was significant only in women not on HRT. There was a highly significant negative correlation of lumbar (L2-4) BMD and 0700 h salivary cortisol in older men (r = -0.31, p = .0003). CONCLUSIONS: Salivary cortisol is a simple, nonstressful method for assessing activity of the hypothalamic-pituitary-adrenal (HPA) axis in the elderly population. A major finding was an elevation in the late night nadir in cortisol secretion. We also suggest that elevated cortisol secretion in elderly people may contribute to the age-related loss in bone mineral density and that this effect is prevented by HRT.

Mandibular and palatal tori, bone mineral density, and salivary cortisol in community-dwelling elderly men and women.

BACKGROUND: This investigation evaluated the relationship between the presence of tori and bone mineral density (BMD) and salivary cortisol levels. METHODS: A total of 230 healthy, community-dwelling elderly men (n = 129) and women (n = 101) aged 60 and older participated in this study. Forty-three women were on hormone replacement therapy (HRT). This was a component of a 5-year longitudinal study measuring subjects' body composition, hormone levels, physical activity, and diet every 6 months. Subjects were examined for the presence of tori by visual inspection and digital palpation. BMD at six sites was measured by dual-energy X-ray absorptiometry. Salivary cortisol levels were measured by radioimmunoassay. RESULTS: Twenty-three percent of all subjects had mandibular tori, 13% had palatal tori, and 12% had both mandibular and palatal tori. Mandibular tori were more common in men, and palatal tori were more common in women. The presence of mandibular tori was significantly correlated with BMD of the lumbar spine, femoral neck, trochanter, and Ward's triangle for all subjects, and with the femoral neck and trochanter of women not on HRT. Men with palatal tori had lower levels of salivary cortisol in the evening. CONCLUSIONS: This study documented the high prevalence of mandibular and palatal tori in a group of 230 elderly, community-dwelling subjects. Women not on HRT and all subjects taken as a group with mandibular tori had higher BMD. The presence of tori at young adulthood may be a marker of higher BMD in the future and of a lower risk for developing osteoporosis.