Nicholas Hill | Tufts Medical Center (original) (raw)

Papers by Nicholas Hill

Obstet Gynecol Surv, 1990

The cause of vaginal bleeding in girls of 10 years and under is reviewed. Of the 52 patients seen... more The cause of vaginal bleeding in girls of 10 years and under is reviewed. Of the 52 patients seen, in 28 (54%) bleeding was caused by a local lesion and 11 (21%) of these had malignant genital tumours. Eleven (21%) children presented with some form of precocious puberty, and in 13 (25%) patients no cause could be found.

Chest Journal, Feb 1, 2011

We hypothesized that the total face mask (TFM) would be perceived as more comfortable than a stan... more We hypothesized that the total face mask (TFM) would be perceived as more comfortable than a standard oronasal mask (ONM) by patients receiving noninvasive mechanical ventilation (NIV) therapy for acute respiratory failure (ARF) and would be quicker to apply by respiratory therapists. Sixty patients presenting with ARF were randomized to receive NIV via either an ONM or a TFM. Mask comfort and dyspnea were assessed using visual analog scores. Other outcomes included time required to apply, vital signs and gas exchange at set time points, and early NIV discontinuation rates (ie, stoppage while still requiring ventilatory assistance). Mask comfort and dyspnea scores were similar for both groups through 3 h of use. The time required to apply the mask (5 min [interquartile range (IQR), 2-8] vs 3.5 min [IQR, 1.9-5]), and duration of use (15.7 h [IQR, 4.0-49.8]) vs 6.05 h [IQR, 0.9-56.7]) were not significantly different between the ONM and the TFM group, respectively. Except for heart rate, which was higher at baseline in the TFM group, no differences in vital signs or gas exchange were detected between the groups during the first 3 h (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; .05). Early NIV discontinuation rates were similar for both the ONM group and TFM group (40% vs 57.1%); however, eight patients in the TFM group were switched to an ONM within 3 h, and none from the ONM group was switched to a TFM (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .05). Among patients with ARF requiring NIV, the ONM and TFM were perceived to be equally comfortable and had similar application times. Early NIV discontinuation rates, improvements in vital signs and gas exchange, and intubation and mortality rates were also similar. ClinicalTrials.gov; No.: NCT00686257; URL: www.clinicaltrials.gov.

American Journal of Physiology Lung Cellular and Molecular Physiology, May 1, 1999

To determine whether atrial natriuretic peptide (ANP) plays a physiological role in modulating pu... more To determine whether atrial natriuretic peptide (ANP) plays a physiological role in modulating pulmonary hypertensive responses, we studied mice with gene-targeted disruption of the ANP gene under normoxic and chronically hypoxic conditions. Right ventricular peak pressure (RVPP), right ventricle weight- and left ventricle plus septum weight-to-body weight ratios [RV/BW and (LV+S)/BW, respectively], and muscularization of pulmonary vessels were measured in wild-type mice (+/+) and in mice heterozygous (+/-) and homozygous (-/-) for a disrupted proANP gene after 3 wk of normoxia or hypobaric hypoxia (0.5 atm). Under normoxic conditions, homozygous mutants had higher RVPP (22 +/- 2 vs. 15 +/- 1 mmHg; P < 0.05) than wild-type mice and greater RV/BW (1.22 +/- 0.08 vs. 0.94 +/- 0.07 and 0.76 +/- 0.04 mg/g; P < 0.05) and (LV+S)/BW (4.74 +/- 0. 42 vs. 3.53 +/- 0.14 and 3.18 +/- 0.18 mg/g; P < 0.05) than heterozygous or wild-type mice, respectively. Three weeks of hypoxia increased RVPP in heterozygous and wild-type mice and increased RV/BW and RV/(LV+S) in all genotypes compared with their normoxic control animals but had no effect on (LV+S)/BW. After 3 wk of hypoxia, homozygous mutants had higher RVPP (29 +/- 3 vs. 23 +/- 1 and 22 +/- 2 mmHg; P < 0.05), RV/BW (2.03 +/- 0.14 vs. 1.46 +/- 0.04 and 1.33 +/- 0.08 mg/g; P < 0.05), and (LV+S)/BW (4.76 +/- 0.23 vs. 3.82 +/- 0.09 and 3.44 +/- 0.14 mg/g; P < 0.05) than heterozygous or wild-type mice, respectively. The percent muscularization of peripheral pulmonary vessels was greater in homozygous mutants than that in heterozygous or wild-type mice under both normoxic and hypoxic conditions. We conclude that endogenous ANP plays a physiological role in modulating pulmonary arterial pressure, cardiac hypertrophy, and pulmonary vascular remodeling under normoxic and hypoxic conditions.

Can J Bot, 1994

... Berry consumption by the American Robin and the subsequent effect on seed germina-tion, plant... more ... Berry consumption by the American Robin and the subsequent effect on seed germina-tion, plant vigour, and dispersal of Vacciniurn angustifolium. ... 1. Daniel J.BellD.J. Bella(email: Daniel_J._Bell@umit.maine.edu)Lisa J.RowlandL.J. Rowlandb301-504-6654fax: 301-504-5062 ...

Environmental Toxicology and Chemistry, Feb 1, 2009

Disturbances such as dredging, storms, and bioturbation result in the resuspension of sediments. ... more Disturbances such as dredging, storms, and bioturbation result in the resuspension of sediments. This may affect sessile organisms that live on hard substrates directly above the sediment. Localized sediment contamination exists around many Antarctic research stations, often resulting in elevated contamination loads in marine sediments. To our knowledge, the potential impact of resuspended contaminated sediments on sessile fauna has not been considered, so in the present study, we assessed the sensitivity of Antarctic spirorbid polychaetes to aqueous metals and to metal-contaminated sediments that had been experimentally resuspended. Worms were first exposed to aqueous metals, both singly and in combination, over 10 d. Spirorbid mortality was tolerant to copper (median lethal concentration [LC50], 570 g/L), zinc (LC50, Ͼ4,910 g/L), and lead (LC50, Ͼ2,905 g/L); however, spirorbid behavior responded to copper concentrations as low as 20g/L. When in combination, zinc significantly reduced mortality caused by copper. A novel technique was used to resuspend sediments spiked with four concentrations of three metals (up to 450 g/g dry wt of copper, 525 g/g dry wt of lead, and 2,035 g/g dry wt of zinc). The response of spirorbids to unfiltered suspended sediment solutions and filtered solutions (aqueous metal exposure) was measured. Suspended sediments were toxic to filter-feeding spirorbids at concentrations approximating those found in contaminated Antarctica areas. Toxicity resulted both from aqueous metals and from metals associated with the suspended sediments, although suspended clean sediments had no impact. To our knowledge, the present study is the first to show that resuspension of contaminated sediments can be an important pathway for toxicity to Antarctic hard substrate organisms. Based on the present results, current sediment-quality guidelines used in the evaluation of Australian sediments may be applicable to Antarctic ecosystems.

The Canadian Field Naturalist, Jan 3, 2014

Journal of animal science, 2005

Fourteen Hereford steers were used to compare carcass traits, meat quality, and fatty acid compos... more Fourteen Hereford steers were used to compare carcass traits, meat quality, and fatty acid composition of beef from cattle grazing tall fescue infected with either wild-type (E+; n = 6) or novel, nil ergot alkaloid (AR542; n = 8) endophyte for 209 d. Average daily gain, live weight, and HCW were greater (P < 0.05) for AR542 cattle than for E+. No differences in LM color or pH were observed between AR542 and E+. Steaks from E+ cattle tended (P = 0.10) to have higher L* and b* than those from AR542 cattle at 0 d of display. Ground beef from E+ cattle also had higher (P < 0.05) L* than AR542 cattle, with no differences in a* or b* at 0 d of display. Color changes during display did not differ for both steaks and ground beef from E+ and AR542. Lipid oxidation levels increased (P < 0.05) during simulated retail display, but they did not differ between endophyte treatments. Adipose tissues from E+ cattle had a higher (P < 0.05) percentage of SFA, and a lower (P < 0.05) perc...

Journal of Ecology, 2005

1 The fleshy fruited species of Vaccinium are known for their spatial dispersal ability but have ... more 1 The fleshy fruited species of Vaccinium are known for their spatial dispersal ability but have generally been found to have poor representation in soil seed banks. 2 A buried seed experiment was conducted with 28 species of Vaccinium , in which seed lots were exhumed at intervals for up to 17 years. Mean species seed longevity was 8.65 years. For five species that persisted in soil for 15-17 years, regression indicates survival times of more than 20 years. 3 Climatic factors (particularly annual temperature range in the centre of the species' distribution range) alone accounted for 42% of the variation in seed longevity and reproductive variables for 55%. 4 Models of fruit dispersal speed (rapid/tardy) demonstrated the link between spatial and temporal (seed longevity) dispersal and between spatial dispersal and habitat affinity (open/closed) of a species. The majority (87%) of species belonged to two of the four possible syndromes (rapid fruit dispersal/long-term seed persistence or tardy dispersal/ short-term persistence); 84% of the former were open habitat species. 5 Seed bank density is a function of seed potential longevity, seed rain and soil conditions. Regions that support species having greatest potential longevity have the smallest seed banks. Annual temperature range was positively correlated with potential longevity but negatively correlated with actual seed bank densities. 6 Lack of recruitment via seed in Vaccinium species in arctic regions may limit genetic variability in these clonal plants and impede population responses to climate changes.

Crop Science, 2009

ABSTRACT Use of nontoxic endophytes in forage tall fescue [Schedonorus phoenix (Scop.) Holub.] is... more ABSTRACT Use of nontoxic endophytes in forage tall fescue [Schedonorus phoenix (Scop.) Holub.] is a preferred strategy to overcome fescue toxicosis. Endophytes are transmitted through the seed, but suffer mortality preferentially to the embryo during storage. Loss of viable endophyte reduces the value of the seed, so increasing storage life would be a benefit. The objectives of this study were to examine (i) viability of an endophyte AR542 in different tall fescue cultivars and endophytes AR542 and AR584 in a Jesup tall fescue seed when stored for extended periods of time, and (ii) heritability of endophyte persistence during seed storage. Seed from each population were stored at room temperatures for 18 mo. Jesup plants containing endophyte after 18 mo of seed storage were placed into polycross blocks. Seed from the selected and parent populations, Jesup with toxic endophyte, and Grasslands Flecha with AR542, were stored at 30 degrees C for 22 mo and tested for endophyte monthly. Pairwise t tests and regression analysis were performed to describe the population responses to storage conditions. Heritability of endophyte viability during storage was calculated. Endophyte AR542 viability during storage was greatest in Flecha followed by Jesup and least in Advance, a third tall fescue cultivar studied in addition to Jesup and Flecha. Endophyte AR584 had greater viability during storage than did AR542 when in Jesup. Selection for endophyte survival increased endophyte viability in stored seed and had heritabilities of 38 and 63% for AR542 and AR584, respectively.

Crop Science, 2006

Evaluating Fusarium head blight (FHB) involves inoculating barley (Hordeum vulgare L.) with Fusar... more Evaluating Fusarium head blight (FHB) involves inoculating barley (Hordeum vulgare L.) with Fusarium graminearum Schwabe [teleomorph Gibberella zeae (Schwein.) Petch] followed by visual observation of disease and analysis for deoxynivalenol (DON). Disease symptoms and DON are not always correlated because both are affected by environmental variables. The objective of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for quantification of FHB in barley. Antibodies to F. graminearum were tested for reaction with other Fusarium spp. Antibodies from cell line IF8 reacted with Fusarium spp. tested, but not other Ascomycota. The ELISA method was developed using seed lots with no, low, and high levels of DON. Quantity of seed, volume of extraction buffer, and agitation time were tested and Fusarium quantified with ELISA. Five genotypes each for high, medium, and low ELISA values were selected from a field experiment using a doubled-haploid mapping population in 2003. The lines were grown in 2004 and scored for FHB, DON, and ELISA. ELISA had lower error than FHB or DON. Lines selected for low, medium, and high ELISA in 2003 had low, medium, and high ELISA values in 2004. ELISA and DON were correlated in both field experiments (r 5 0.51). ELISA and DON were correlated (r 5 0.71) in samples selected from grain elevators in 1993 through 2003 indicating naturally occurring Fusarium spp. outside the B clade had no effect on the performance of the ELISA analysis.

Botany, 2011

Forest herbs account for greater species richness than any other plant type in deciduous forests ... more Forest herbs account for greater species richness than any other plant type in deciduous forests and are the most vulnerable to anthropogenic disturbances. We examined whether the limited distribution of rare Appalachian forest herbs in Nova Scotia is related to edaphic specialization or a history of anthropogenic disturbance. Remnant populations are restricted to floodplain forest, where both habitat factors and disturbance history differ significantly from those of adjacent upland sugar maple forest. Contrasting soil and litter layers between floodplain stands and adjacent upland sites revealed the latter to be deficient in key cations (calcium, magnesium, boron); however, regression models for uplands and for floodplains showed that native herb richness was related to soil fertility in each case. Soil calcium accounted for most of the species richness variation among floodplains for native herbs and for a large seeded guild that contains most of the rare species on floodplains. Given the widespread anthropogenic decalcification of forest soils throughout eastern North America, conservation efforts must (i) increase and connect deciduous forest floodplain ecosystems and (ii) understand how to manage and create suitable cation-rich migration corridors in the forest landscape.