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J S McLaren

Publications and source records attributed to J S McLaren.

6 recordsLinked to original sources
PubMed2004

Photoperiodic effects on body mass, energy balance and hypothalamic gene expression in the bank vole.

We examined the effect of increasing photoperiod, at a constant low temperature, on the body mass and energy budget of the bank vole Clethrionomys glareolus. Simultaneously, we determined the hypothalamic gene expression of neuropeptides and receptors known to be involved in short-term energy balance. Despite an increase in body mass (approximately 10% of initial mass), we found no significant changes in any energetic parameters (food intake, energy assimilation rate, resting metabolic rate and total daily energy expenditure by doubly-labelled water). Apparent energy assimilation efficiency was higher in voles exposed to long-days (LD) compared to short-days (SD). Surprisingly, gene expression of corticotrophin releasing factor (CRF; in the paraventricular nucleus), and the melanocortin-3 receptor (in the arcuate nucleus), both known to be involved in appetite suppression and elevation of energy expenditure in short-term energy balance, were higher in voles kept in LD compared to SD. CRF expression was also elevated in females compared to males. These paradoxical data suggest an alternative mechanism for the control of seasonal body mass changes compared to short-term body mass changes, and between male and female voles. Furthermore, they highlight the need for studies to perform simultaneous measurements at both the molecular and whole animal levels.

Animals↗
PubMed2001

The diagnostic value of anti-neutrophil cytoplasmic antibody testing in a routine clinical setting.

Anti-neutrophil cytoplasmic antibody (ANCA) tests are a routine clinical assay in most UK hospitals. We examined the role of routine ANCA testing in achieving a diagnosis of systemic vasculitis in a routine clinical setting. From April 1996 to March 2000, 2734 samples from five hospital departments were tested for ANCA by indirect immunofluorescence (IIF) at a single laboratory. After April 1999, enzyme-linked immunosorbent assays (ELISAs) were performed on all IIF-positive samples. Clinical diagnosis was determined for all patients with a positive IIF ANCA, and a sample of the ANCA-negative patients. Some 2-18% of patients with suspected ANCA-associated systemic vasculitis (AASV) had positive IIF ANCA. The AASV diagnosis was confirmed in 0-56% of these cases. Analysis by department suggested that 88-100% of patients with a positive IIF ANCA did not have AASV, except in the Rheumatology department. The positive predictive value (PPV) of IIF ANCA for AASV was 59% and the negative predictive value (NPV) was 84%. Of the patients with proven AASV, 41% did not have ANCA on IIF. Combined ANCA testing by IIF/ELISA had a higher sensitivity and PPV but lower specificity than IIF alone for AASV. For the combined IIF/ELISA test, only the Rheumatology department had a sensitivity or PPV >0% for AASV. The PPV of ANCA by IIF/ELISA for AASV was 79% and the NPV was 63%. The ANCA test is being widely applied with very poor return. Guidelines for more effective usage are proposed.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2000

Effect of long-term cold exposure on antioxidant enzyme activities in a small mammal.

Aerobic organisms continually face exposure to reactive oxygen species (ROS) and many have evolved sophisticated antioxidant systems to effectively remove them. Any increase in ROS production or weakening in this defense system may ultimately lead to oxidative stress and cellular damage. We investigated whether long-term cold exposure, which is known to lead to an elevation in metabolic rate, increased the activities of the ROS-scavenging enzymes, catalase (CAT), selenium-dependent glutathione peroxidase (GPx), and total superoxide dismutase (Total-SOD) in liver, cardiac muscle, kidney, skeletal muscle (vastus lateralis), and duodenum of short-tailed field voles (Microtus agrestis), born and maintained at either 8 +/- 3 degrees C or 22 +/- 3 degrees C. CAT, GPx, and Total-SOD activities were determined at age 61 +/- 1.9 days. An increase in CAT activity in voles maintained at 8 +/- 3 degrees C was observed in skeletal muscle (71%) and kidney (20%), with both CAT and GPx activities significantly elevated (by 40 and 43%, respectively) in cardiac muscle, when compared to voles at 22 +/- 3 degrees C. Total-SOD activity and protein content did not differ significantly between groups in any tissue. We suggest that the compensatory increases in CAT (skeletal muscle, cardiac muscle, kidney) and GPx (cardiac muscle), but not Total-SOD activities, resulting from long-term cold exposure may reflect the elevated metabolic rate, and possibly also increased ROS production, at this time.

Acclimatization↗
PubMed2000

Agricultural biotechnology: myth and measurement.

The title of this article could easily have been "The Inquisition, The First 100 Million Acres, and Future Quantification Challenges." After approximately 20 years of research, transgenic crops have made it through the maze of scientific and regulatory testing to reach commercial practice and have been adopted at a rapid rate. Plant scientists and growers have quickly recognized the extensive portfolio of benefits that can be obtained: it is analogous to the discovery of electricity (biotech) in a world of candles (conventional breeding). Despite the potential for advancement, a few groups have revolted against biotechnological crops. Misinformation has been used to capture headlines, and good scientific research principles have been castigated by self-appointed judges. Conversely, the probiotech camp has not been good at communicating in a broadly understandable manner, but they have the weight of scientific evidence on their side. There are 100 million acres of commercial transgenic crops, and more than 30,000 intensive field trials have been performed, but not one shred of reproducible evidence indicates that biotechnological crops are dangerous, unsafe, or a threat to the environment. Looking ahead, dozens of new beneficial traits are being explored in laboratories across the world, and their application will bring new issues and more difficult challenges. For example, several genes may be stacked in different combinations to provide trait sets with various levels of added value. These crops will no longer be traded as bulk-mixed commodities; therefore, some mechanism will be required to measure the value at each transaction point. The need to develop standards, operating procedures, and devices for accurate, real-time quantification of multiple possible trait sets may be one of the major limitations to rapid future progress in some sectors of crop biotechnology.

Biotechnology↗
PubMedDate not supplied

Diagnosis and assessment of systemic vasculitis.

The diagnosis of systemic vasculitis requires clinical evidence with appropriate symptoms and physical signs, supported by histological or radiological confirmation. Earlier recognition of these diseases has been facilitated by a greater awareness of their incidence, and also by the more widespread introduction of the anti-neutrophil cytoplasmic antibody (ANCA) test. Early diagnosis provides a greater potential for effective intervention in the course of disease and this may limit subsequent damage. However, an early diagnosis poses the more difficult challenge in the classification of the vasculitides, since traditional classification systems have depended on the presence of well-established manifestations of the disease. The accurate assessment of disease activity and damage in vasculitis has become necessary as a result of significant improvements in survival with the use of chemotherapy. The disease course however is frequently characterised by relapse as well as the scars of irreversible organ damage from disease and drug toxicity. Clinical methods of assessment are simple to apply, reliable and often more effective than any current laboratory test in evaluating the effects of therapy and determining changes in therapy. The increasing use of surrogate clinical measures of disease should provide a greater opportunity to establish the effectiveness of existing and novel therapies in the management of these complex diseases.

Antibodies, Antineutrophil Cytoplasmic↗