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Biomedical subjects

S Nicol

Publications and source records attributed to S Nicol.

At least 19 recordsLinked to original sources
PubMed2006

DNA as a dietary biomarker in Antarctic krill, Euphausia superba.

The diet of Antarctic krill (Euphausia superba) has been studied using a variety of techniques, but current methods still suffer from problems that are difficult to solve. This study examined an alternative approach utilizing DNA as a prey biomarker. Methods were developed for the preservation, extraction, and identification of prey DNA from krill collected in the field. Group-specific polymerase chain reaction (PCR) was used to amplify diatom prey (Phylum: Bacillariophyta) and the results from DNA clone libraries were compared with microscopic diet analysis. DNA analysis was superior to microscopy for prey detection. However, differences in prey relative abundance estimates between the two techniques suggested some bias in the DNA-based estimates. Quantification showed that large amounts of prey DNA had been successfully preserved and extracted. Overall the results suggest that the application of DNA-based diet analysis to krill warrants further investigation, particularly for prey that are difficult to study using other methods.

Animals↗
PubMed2002

Genetic differentiation in the Antarctic coastal krill Euphausia crystallorophias.

The population genetics of the Antarctic neritic krill species Euphausia crystallorophias was examined by nucleotide sequence variation in its mitochondrial DNA. A 616 base pair region of the cytochrome c oxidase subunit I (COI) gene was screened for mutations by single-strand conformational polymorphism (SSCP) combined with restriction digestion. E. crystallorophias caught in three different regions of the Antarctic coastline were used--two samples from the Mertz Glacier Polynya and one sample each from the western side of the Antarctic Peninsula and from the Davis Sea. Significant genetic differences between krill samples were identified. However, the extent of these differences did not correlate with the degree of geographic separation between the sampling sites. This suggests that the genetic structuring may be the result of small-scale differentiation rather than differentiation between resident populations in separate parts of the Southern Ocean. The possibility that genetic differences between samples within a region are as important as differences between regions has implications for other studies of krill population genetics.

Animals↗
PubMed2001

Monotreme IGF2 expression and ancestral origin of genomic imprinting.

IGF2 (insulin-like growth factor 2) and M6P/IGF2R (mannose 6-phosphate/insulin-like growth factor 2 receptor) are imprinted in marsupials and eutherians but not in birds. These results along with the absence of M6P/IGF2R imprinting in the egg-laying monotremes indicate that the parental imprinting of fetal growth-regulatory genes may be unique to viviparous mammals. In this investigation, we have cloned IGF2 from two monotreme mammals, the platypus and echidna, to further investigate the origin of imprinting. We report herein that like M6P/IGF2R, IGF2 is not imprinted in monotremes. Thus, although IGF2 encodes for a highly conserved growth factor in chordates, it is only imprinted in therian mammals. These findings support a concurrent origin of IGF2 and M6P/IGF2R imprinting in the late Jurassic/early Cretaceous period. The absence of imprinting in monotremes, despite apparent interparental conflicts over maternal-offspring exchange, argues that a fortuitous congruency of genetic and epigenetic events may have limited the phylogenetic breadth of genomic imprinting to therian mammals. J. Exp. Zool. (Mol. Dev. Evol.) 291:205-212, 2001.

Amino Acid Sequence↗
PubMed2001

Energetics of foraging and locomotion in the platypus Ornithorhynchus anatinus.

We measured the energy requirements of platypuses foraging, diving and resting in a swim tank using flow-through respirometry. Also, walking metabolic rates were obtained from platypuses walking on a conventional treadmill. Energy requirements while foraging were found to depend on water temperature, body weight and dive duration and averaged 8.48 W kg(-1). Rates for subsurface swimming averaged 6.71 W kg(-1). Minimal cost of transport for subsurface swimming platypuses was 1.85 J N(-1)m(-1) at a speed of 0.4 m s(-1). Aerobic dive limit of the platypus amounted to 59 s. Metabolic rate of platypuses resting on the water surface was minimal with 3.91 W kg(-1) while minimal RMR on land was 2.08 W kg(-1). The metabolic rate for walking was 8.80 W kg(-1) and 10.56 W kg(-1) at speeds of 0.2 m s(-1) and 0.3 m s(-1), respectively. A formula was derived, which allows prediction of power requirements of platypuses in the wild from measurements of body weight, dive duration and water temperature. Platypuses were found to expend energy at only half the rate of semiaquatic eutherians of comparable body sizes during both walking and diving. However, costs of transport at optimal speed were in line with findings for eutherians. These patterns suggest that underwater locomotion of semiaquatic mammals have converged on very similar efficiencies despite differences in phylogeny and locomotor mode.

Animals↗
PubMed2001

The relationship between health-related quality of life and weight loss.

OBJECTIVE: This is a report of health-related quality of life (HRQOL) changes in obese patients completing at least 1 year of outpatient treatment in a weight reduction program combining phentermine-fenfluramine and dietary counseling. RESEARCH METHODS AND PROCEDURES: Participants were 141 women (87.6%) and 20 men (12.4%) who had an average body mass index at intake of 41.1 kg/m(2) (SD = 7.0, range = 29.5 to 67.0 kg/m(2)) and an average age of 44.9 years (SD = 9.3, range = 23 to 65 years). HRQOL was assessed at intake and at 1-year follow-up using the Impact of Weight on Quality of Life (IWQOL)-Lite questionnaire. The relationship between HRQOL changes and weight loss was examined using Pearson correlations. Clinically meaningful change in HRQOL was defined as a 1.96 SEM reduction in IWQOL-Lite total score. RESULTS: On average, participants lost 20.2 kg or 17.6% of their weight over the 1-year period. Of the participants, 15.5% lost <10% of their weight, 24.2% lost 10% to 14.9%, 23.6% lost 15% to 19.9%, and 36.6% lost 20% or more. All five IWQOL-Lite scales and total score showed statistically significant improvement over the 1-year period. Changes in IWQOL-Lite scores from intake to 1 year showed statistically significant correlations with percentage of weight loss for all subscales and total score. Subscale correlations with weight loss ranged from 0.166 (Public Distress) to 0.396 (Physical Function) and was 0.370 for the total score. Forty-four percent of participants losing <10% met the criterion of clinically meaningful change, compared with 51.3% losing 10% to 14.9%, 55.3% losing 15% to 19.95%, and 76.3% losing >20%. For total score and for three of the five IWQOL-Lite scales (Physical Function, Self-Esteem, and Sexual Life), the relationship between weight loss and clinically meaningful change was linear and was significant at p < 0.05. Physical Function and Self-Esteem were most strongly affected by weight loss. DISCUSSION: HRQOL changes, as measured by an obesity-specific instrument (IWQOL-Lite), are strongly related to weight reduction.

Adult↗
PubMed2000

Antarctic krill (Euphausia superba) acquire a UV-absorbing mycosporine-like amino acid from dietary algae.

We hypothesised that Antarctic krill acquire UV-absorbing mycosporine-like amino acids (MAAs) from dietary algae, which produce MAAs in response to ultraviolet (UV) irradiation. To test this hypothesis, we grew cultures of Phaeocystis antarctica that had been grown under either photosynthetically active radiation (PAR, 400-750 nm) plus UV irradiation (UVR, 280-400 nm), or else PAR-only. Algae grown under PAR-only produced high concentrations of porphyra-334, whereas additional UVR caused formation of high concentrations of mycosporine-glycine:valine and lower concentrations of porphyra-334. Krill were fed with either of these two cultures on eight occasions over 63 days. A third group was starved for the duration of the experiment. Animals were analysed after 36 and 63 days for MAA content. Remaining animals from all treatments were starved for a further 35 days and analysed to examine MAA retention characteristics. Our findings are that krill acquired different MAAs from dietary algae depending on the light conditions under which the algae were grown. Specifically, krill fed algae grown under PAR-only had higher concentrations of porphyra-334 than starved krill. Conversely, krill fed algae grown under PAR with additional UVR had high body concentrations of mycosporine-glycine:valine. MAA concentrations in starved krill remained static throughout the experiment. However, long term starvation (35 days) caused levels of certain acquired MAAs to decline. From this we can infer that MAA concentrations in krill are dependent on the MAA content of phytoplankton, and therefore the algae's response to UV exposure. This has implications for transfer of MAAs through marine trophic webs.

Journal Article↗
PubMed2000

Ocean circulation off east Antarctica affects ecosystem structure and sea-ice extent.

Sea ice and oceanic boundaries have a dominant effect in structuring Antarctic marine ecosystems. Satellite imagery and historical data have identified the southern boundary of the Antarctic Circumpolar Current as a site of enhanced biological productivity. Meso-scale surveys off the Antarctic peninsula have related the abundances of Antarctic krill (Euphausia superba) and salps (Salpa thompsoni) to inter-annual variations in sea-ice extent. Here we have examined the ecosystem structure and oceanography spanning 3,500 km of the east Antarctic coastline, linking the scales of local surveys and global observations. Between 80 degrees and 150 degrees E there is a threefold variation in the extent of annual sea-ice cover, enabling us to examine the regional effects of sea ice and ocean circulation on biological productivity. Phytoplankton, primary productivity, Antarctic krill, whales and seabirds were concentrated where winter sea-ice extent is maximal, whereas salps were located where the sea-ice extent is minimal. We found enhanced biological activity south of the southern boundary of the Antarctic Circumpolar Current rather than in association with it. We propose that along this coastline ocean circulation determines both the sea-ice conditions and the level of biological productivity at all trophic levels.

Animals↗
PubMed2000

Descriptive study of the diaphragm and lungs in the short-nosed echidna, Tachyglossus aculeatus (Mammalia: monotremata).

In this descriptive study, we characterize the diaphragm and lungs of the short-nosed echidna, Tachyglossus aculeatus, using a combination of gross anatomical, light-microscopic, electron microscopic, and morphometric techniques, including airway casting. The diaphragm is inclined from ventro-cranial to dorso-caudal and possesses a large central tendon (centrum tendineum). The crural and costal muscle groups and the associated trigoni are located in the same positions as in other mammals. The bronchial branching pattern reveals cranially broad, tapering stem bronchi and an unusually small number of first order bronchi. The asymmetrical primary branching pattern and possibly also the asymmetry of right and left lungs are plesiomorphic within the Mammalia. The histology and ultrastructure of the airways and lung parenchyma reveal no unusual features: alveolar type 1 and type 2 cells in the parenchyma; type 2 cells, exocrine bronchiolar cells (Clara cells), ciliated cells, and goblet cells in the terminal airways and the latter two cell types in the bronchi. Both a double and a single capillary net are found on the interalveolar septa. The high capillary loading of the double net may be of selective advantage because of long apneas and low metabolic rate in the echidna.

Animals↗
PubMed2000

28S rDNA evolution in the Eumalacostraca and the phylogenetic position of krill.

The Malacostraca are an ancient and morphologically diverse class of Crustacea. The phylogenetic position of one order within this class, the Euphausiacea ("krill," subclass Eumalacostraca) was investigated using 28S rDNA sequences from representatives of several malacostracan orders. Phylogenies for these sequences were estimated by maximum-likelihood and maximum-parsimony analysis. The results of these analyses produced a new scheme for evolution within the Eumalacostraca. The new phylogenies suggested that Euphausiacea are most closely related to the Mysida and not the Decapoda, as is generally thought. Furthermore, the Mysida were found not to be closely related to the Lophogastrida, which are often considered their sister taxon. These hypotheses were tested against the hypotheses of monophyly for the Eucarida, Mysidacea, and Peracarida and found to be significantly better on the basis of the 28S rDNA data.

Animals↗
PubMed2000

Phase II trial of gemcitabine in patients with previously untreated metastatic cancer of the esophagus or gastroesophageal junction.

BACKGROUND: There were approximately 12,500 cases of esophageal carcinoma diagnosed in the US in 1992 and 12,200 deaths. The impact of chemotherapy on patients with metastatic disease is marginal with a median survival of only five months. Gemcitabine (LY188011,2,2,-difluorodeoxycytidine: dFdC), an analog of cytosine arabinoside (ara-C), is a pyrimidine antimetabolite. Gemcitabine has shown interesting clinical activity in initial phase II clinical trials in a variety of malignancies, including the aerodigestive malignancies, squamous-cell carcinoma of the head/neck and both non-small-cell and small-cell lung cancer. PATIENTS AND METHODS: A total of 21 patients with chemotherapy-naïve metastatic esophageal carcinoma were entered. Nineteen patients were evaluable for toxicity and seventeen patients were evaluable for response. Gemcitabine was administered intravenously at 1250 mg/m2 over 30-60 minutes on days 1, 8, and 15 followed by 1 week of rest. This four-week schedule defined a cycle of treatment. Patients may have received a maximum of six cycles. RESULTS: Gemcitabine was well tolerated with minimal non-hematologic toxicity and grade 3-4 anemia, granulocytopenia, and thrombocytopenia occurring in 10.5%, 21%, and 0% of patients, respectively. No responses were seen in the seventeen evaluable patients. CONCLUSIONS: At the dose and schedule studied it would appear that gemcitabine has no activity in patients with chemotherapy-naïve esophageal carcinoma.

Adenocarcinoma↗
PubMed2000

Phase II trial of gemcitabine plus cisplatin in patients with metastatic urothelial cancer.

PURPOSE: To assess the activity and toxicity of the combination of gemcitabine and cisplatin in the treatment of chemotherapy-naive patients with metastatic urothelial cancer. PATIENTS AND METHODS: Forty-six patients with measurable stage IV carcinoma of the urothelium were enrolled onto this trial. Gemcitabine 1,000 mg/m(2) was administered intravenously for 30 to 60 minutes on days 1, 8, and 15 of each 28-day cycle. Cisplatin was administered after gemcitabine on day 1 of each cycle. The first 11 patients received an initial cisplatin dose of 100 mg/m(2). Due to the hematologic toxicity observed in several of these patients, the dose was reduced to 75 mg/m(2) in the remaining 35 patients. Patients were treated with six cycles, unless disease progression or severe toxicity necessitated earlier discontinuation. RESULTS: Ten of the 46 patients achieved a complete response and nine showed a partial response. The overall response rate was 41%. The median time to treatment failure was 5.5 months. The median survival was 14.3 months, and the 1-year survival probability was 54%. Most of the toxicities were hematologic and, in general, easily manageable. CONCLUSION: Gemcitabine plus cisplatin is active in the treatment of metastatic urothelial cancer in chemotherapy-naive patients and has an acceptable clinical safety profile. Studies are under way to further define the place of gemcitabine in combination with other chemotherapeutic agents in the treatment of metastatic urothelial cancer.

Adult↗
PubMed1999

Selective immunoclean-up followed by liquid or gas chromatography for the monitoring of polycyclic aromatic hydrocarbons in urban waste water and sewage sludges used for soil amendment.

A selective clean-up procedure using immunoaffinity solid-phase extraction was applied for the trace-level determination of polycyclic aromatic hydrocarbons (PAHs) in urban waste water and sewage sludges used for soil amendment. Anti-pyrene antibodies have been immobilized on a silica-based sorbent and the cross-reactivity of the antibodies towards structurally related compounds were allowed to extract the whole class of priority PAHs. The selectivity of the antibodies provided clean extracts from sludges and, therefore, the identification and quantification were shown to be easier using either liquid chromatography (LC) with UV diode array and fluorescence detection in series or gas chromatography-mass spectrometry (GC-MS), although some loss of up to 50% was observed for the clean-up. The identification of the PAHs by matching of UV and MS spectra was greatly improved. The procedure, including immunoclean-up and LC coupled to diode array and fluorescence detection, was validated using certified reference materials with native PAHs of concentrations in the range of 0.57-2.16 mg/kg (dry sludges).

Chromatography, Gas↗
PubMed1998

Sublingual hyoscyamine for patient comfort during screening sigmoidoscopy: a randomized, double-blind, placebo-controlled clinical trial.

BACKGROUND: Screening sigmoidoscopy is an underutilized method for detecting early colorectal cancer, and patient discomfort is one reason for poor compliance in the general population. The possible benefit of a well-tolerated, low-cost antispasmodic medication, sublingual hyoscyamine, used before flexible sigmoidoscopy was assessed in a randomized, double-blinded, placebo-controlled trial. METHODS: One hundred fifty patients were enrolled and randomized to receive two sublingual hyoscyamine tablets (0.125 mg/tablet) or the placebo 10 minutes before sigmoidoscopy. Patient comfort and the endoscopist's perception of the ease of insertion were measured using a 100 mm visual analog scale. The depth of sigmoidoscope insertion was measured in centimeters, and complications were recorded. RESULTS: The median age was 55 years (range 25 to 83 years). There were 100 men (66.7%) and 50 women (33.3%). Approximately half (n = 76, 50.7%) had a prior sigmoidoscopy or colonoscopy. No statistical differences were found between treatment group means for age, gender, pain score, ease of insertion, or depth of insertion. The hyoscyamine group tended to have lower mean pain (32.4 vs. 37.7, p = 0.18) and difficulty (29.9 vs. 33.7, p = 0.31) scores and greater depth of sigmoidoscope insertion (51.3 vs. 47.7, p = 0.07); however, the differences were not statistically significant. The treatment groups differed with a higher percentage of the hyoscyamine group having a previous endoscopy (60.0% vs. 41.3%, p = 0.02); however, no significant differences were detected between mean pain scores as related to treatment when controlling for previous experience with endoscopy (p = 0.31). CONCLUSIONS: In this study, hyoscyamine administered in the sublingual route did not significantly improve patient comfort, ease of insertion, or the depth of sigmoidoscope insertion during screening sigmoidoscopy. The search for alternative methods to improve patient comfort during screening endoscopy should continue.

Adjuvants, Anesthesia↗
PubMed1998

Learning physiology from cardiac surgery patients.

A number of pressures have led to a very great reduction or complete abandonment of the use of animals in the teaching of physiology in most medical schools. Often animal experiments have been replaced by computer simulations, but a simulation is only as good as the model or algorithm on which it is based and can never contain the depth of information or unpredictability displayed by real animals or patients. We used a computer-based system to collect cardiovascular data from patients instrumented for cardiac surgery, allowing students to "replay" an operation. These recordings were annotated with notes, diagrams and video clips, and a student workbook was written. The resulting package contained a wealth of physiological data and was perceived by students to be very clinically relevant. The very wealth of information, however, tended to overwhelm students, and so a series of introductory Computer tutorials were written to provide students with the background necessary to cope with the clinical data.

Adult↗
PubMed1998

Phase I study of docetaxel dose escalation in combination with fixed weekly gemcitabine in patients with advanced malignancies.

PURPOSE: To determine the maximum-tolerated dose of monthly docetaxel combined with fixed-dose weekly gemcitabine and describe the dose-limiting toxicities (DLTs) of the combination. PATIENTS AND METHODS: Patients with refractory solid tumors were treated with gemcitabine days 1, 8, and 15 every 4 weeks at a fixed dose of 800 mg/m2. Two docetaxel administration schedules were studied, with the drug administered either day 1 or day 15 at doses of 45, 60, 75, and 100 mg/m2 per cycle. RESULTS: Forty patients received 132 cycles of chemotherapy. On the day-1 schedule, the maximum-tolerated docetaxel dose was the highest planned dose of 100 mg/m2 with two DLT episodes among 12 patients treated with 34 cycles at this dose level. On the day-15 schedule, delivery of the planned docetaxel doses was not feasible because of thrombocytopenia and hepatic dysfunction. Hematologic toxicities included grade 4 neutropenia in 16 patients, with three episodes of febrile neutropenia; grades 3 to 4 thrombocytopenia in nine patients; and anemia that required RBC transfusions in 10 patients. For patients treated at the highest docetaxel dose level, myelosuppression was not dose limiting and only one of 34 cycles was complicated by febrile neutropenia. The most common nonhematologic toxicities were asthenia, flu-like symptoms, and fluid retention. Antineoplastic activity was noteworthy, with partial responses in nine of 21 patients with pretreated non-small-cell lung cancer (NSCLC; 43%; 95% confidence interval, 22 to 66), in four of seven patients with breast cancer, and in one patient with esophageal adenocarcinoma. CONCLUSION: Gemcitabine 800 mg/m2 days 1,8, and 15 can be safely combined with docetaxel 100 mg/m2 day 1 of a 28-day cycle. The observed antitumor activity warrants phase II evaluation.

Adult↗