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Biomedical subjects

G Baker

Publications and source records attributed to G Baker.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of fixed sample-size plans for Plutella xylostella (Lepidoptera: Plutellidae) on broccoli crops in Australia.

Fixed sample-size plans for monitoring Plutella xylostella (L.) (Lepidoptera: Plutellidae) on broccoli and other Brassica vegetable crops are popular in Australia for their simplicity and ease of application. But the sample sizes used are often small, approximately 10-25 plants per crop, and it may be that they fail to provide sufficient information upon which to base pest control decisions. We tested the performance of seven fixed sample-size plans (10, 15, 20, 30, 35, 40, and 45 plants) by resampling a large data set on P. xylostella in commercial broccoli crops. For each sample size, enumerative and presence-absence plans were assessed. The precision of the plans was assessed in terms of the ratio of the standard error to the mean; and at least 45 and 35 samples were necessary for the enumerative and presence-absence plans, respectively, to attain the generally accepted benchmark of < or = 0.3. Sample sizes of 10-20 were highly imprecise. We also assessed the consequences of classifications based on action thresholds (ATs) of 0.2 and 0.8 larvae per plant for the enumerative case, and 0.15 and 0.45 proportion of plants of infested for the presence-absence case. Operating characteristic curves and investigations of the frequency of correct decisions suggest improvements in the performance of plans with increased sample size. In both the enumerative and presence-absence cases, the proportion of incorrect decisions was much higher for the lower of the two ATs assessed, and type II errors (i.e., failure to suggest pest control upon the AT is exceeded) generally accounted for the majority of this error. Type II errors are the most significant from a producer's standpoint. Further consideration is necessary to determine what is an acceptable type II error rate.

Animals↗
PubMed2005

Regulation of BMP-induced ectopic bone formation by Ahsg.

alpha2-HS-glycoprotein (Ahsg), also known as fetuin is a serum and bone resident glycoprotein, which binds to TGF-beta superfamily members including bone morphogenetic proteins (BMP) and inhibits dexamethasone-induced osteogenesis in bone marrow cultures in vitro. Here we demonstrate that Ahsg reduces cytokine binding to its cognate receptor in HOS osteocyte cells and suppresses intracellular signaling, while in vivo, we test the hypothesis that Ahsg-deficient mice are hyper-responsive to BMP-induced osteogenesis. Human native BMP was implanted into the hindquarter muscles of Ahsg(+/+), Ahsg(+/-) and Ahsg(-/-) mice and 4 weeks later, ossicle formation was analyzed by radiography, bone density scanning (DEXA) and histomorphometry. Alkaline phosphatase (AP) activity was measured in ossicles as a marker for bone cell differentiation, and was significantly higher in Ahsg(-/-) versus Ahsg(+/-) and/or Ahsg(+/+) mice. Ectopic ossicle size in the Ahsg(+/-) mouse was 4-fold greater than that in the wild type (Ahsg(+/+)), and intermediate to that shown in Ahsg(-/-) mouse. Bone mineral density (BMD) was lower in the Ahsg(-/+) and Ahsg(-/-) mice compared to Ahsg(+/+) littermates. The ratio of cortical to cancellous bone was found to be >2-fold higher in Ahsg(-/-) mouse in comparison to the Ahsg(+/+) mice with no significant change in the Ahsg(-/+) mouse. Finally, a significantly higher incidence of satellite ossification; small islands of immature bone, was shown in Ahsg(-/-) mice as compared to Ahsg(+/+) mice. Although Ahsg binds to TGF-beta/BMP and blocks receptor signalling, it may also sequester cytokines in matrix, thereby acting as a reservoir of osteoinductive activity when released. This may explain the non-linear relationship between ectopic bone formation characteristics and Ahsg(+/+), Ahsg(+/-) and Ahsg(-/-) genotypes, although the increase in satellite bone formation might also explain this phenomenon. Our results suggest that Ahsg may be useful for prevention of the heterotopic ossification and the regulation of osteoinductive effects of BMP used with grafts.

Alkaline Phosphatase↗
PubMed2004

Systematic screening allows reduction of adverse antiepileptic drug effects: a randomized trial.

OBJECTIVE: To determine the effectiveness of systematic screening with a brief 19-item self-report instrument, the Adverse Events Profile (AEP), to reduce adverse effects of antiepileptic drugs (AEDs) and improve subjective health status. METHODS: The authors performed a prospective randomized trial comparing the use of the AEP with usual care without the AEP. Sixty-two patients with an AEP score of >or=45 were enrolled from a consecutive group of 200 consenting adults with epilepsy. RESULTS: The mean percent improvement in AEP scores was greater in the patient group for which clinicians received the AEP compared with the usual care group (25% vs 5%; p < 0.01). Mean change in Quality of Life in Epilepsy Inventory (QOLIE)-89 total scores was not different between groups, but for the entire sample QOLIE-89 change was greater for patients having a 15-point improvement in AEP scores than for those with a 0- to 15-point improvement or a worsened score (24 vs 12 vs 3; analysis of variance, p < 0.008). More patients in the AEP group had a >15-point improvement in QOLIE-89 score (p < 0.03). Use of the AEP was associated with a 2.8-fold increase (95% CI, 1.7 to 4.8) in AED modifications. No difference in seizure rates was observed. CONCLUSIONS: Systematic screening for antiepileptic drug side effects may increase identification of toxicity and guide medication changes to reduce adverse effects and possibly improve subjective health status.

Academic Medical Centers↗
PubMed2004

Inducing Graves' ophthalmopathy.

The majority of patients with Graves' disease (GD) have some degree of ocular involvement and this requires surgical or medical intervention in about 5% of cases. There are autoimmune and inflammatory processes operating in Graves' ophthalmopathy (GO), which together induce glycosaminoglycan production, edema and adipogenesis resulting in an increase in the volume of the orbital contents. GO is a heterogeneous disorder, i.e.: 1) whilst usually associated with hyperthyroidism it may occur in euthyroid (and even hypothyroid) patients; 2) expansion of orbital tissues may be due to 'big-fat' or 'big muscles'. The heterogeneity is further exemplified by the spectrum of protocols which have succeeded in inducing aspects of the disease both in animal models and in humans including: 1) Production of severe hypothyroidism in guinea pigs by thyroidectomy and administration of pituitary extract (TSH); 2) Induction of T cells autoreactive to the thyrotropin receptor (TSHR) in mice; 3) Depletion of regulatory T cells in humans susceptible to autoimmunity; 4) Modulation of adipose tissue metabolism in mice and men. In addition, identical induction protocols result in different pathological features depending on the environment, e.g. TSHR primed T cells produce thyroiditis and ocular pathology in BALBc mice in Brussels but thyroid stimulating antibodies accompanied by elevated thyroxine in these animals (from the same supplier) in Cardiff. Thus, experiences in the induction of GO have confirmed the polygenic, multifactorial nature of the disorder and highlight the importance of careful disease classification to promote further progress in understanding.

Adipose Tissue↗
PubMed2004

The longer term outcome of children born to mothers with epilepsy.

OBJECTIVES: To determine the prevalence of cognitive delay and possible associated dysmorphic features in children exposed to antiepileptic drugs (AEDs) in utero. DESIGN: Retrospective study of children born to mothers with epilepsy. SETTING: Regional epilepsy clinics in Liverpool and Manchester, UK. PARTICIPANTS: Children aged between 6 months and 16 years born to mothers with epilepsy. MAIN OUTCOME MEASURES: Structured interviews, hospital records, clinical examination, and psychometric tests (Wechsler) were used to assess exposure and intelligence quotient (IQ). Blinded assessment of photographs was used to score children with characteristic dysmorphic features. RESULTS: A total of 249 children aged 6 and over were studied: 41 were exposed to sodium valproate, 52 to carbamazepine, 21 to phenytoin, 49 to polytherapy, and 80 were unexposed. Mean verbal IQ was significantly lower in the valproate group compared to unexposed and other monotherapy groups. Multiple regression analysis showed that both valproate exposure and frequent tonic-clonic seizures in pregnancy were significantly associated with a lower verbal IQ despite adjusting for other confounding factors. There was a significant negative correlation between dysmorphic features and verbal IQ in children exposed to valproate. CONCLUSIONS: This study identifies valproate as a drug carrying potential risks for developmental delay and cognitive impairment and is the first to suggest that frequent tonic-clonic seizures have a similar effect. Our results need to be interpreted with caution given their retrospective nature. Women with epilepsy need careful counselling about individual risk benefit of AED treatment before pregnancy.

Abnormalities, Drug-Induced↗
PubMed2003

A randomised controlled trial comparing rehabilitation against standard therapy in multiple sclerosis patients receiving intravenous steroid treatment.

BACKGROUND: There is evidence to support both the use of intravenous methylprednisolone (IVMP) in multiple sclerosis (MS) relapse and physiotherapy in the management of MS, but no studies have investigated the combination of steroids and rehabilitation together. OBJECTIVES: To evaluate the benefits of IVMP with planned, comprehensive multidisciplinary team (MDT) care compared to IVMP with standard care. METHODS: In this randomised controlled trial, patients confirmed to have had a definite MS relapse severe enough to warrant IVMP (1 g daily for three days) were randomised to two groups. The control group was managed according to the standard ward routine; the treatment group received planned coordinated multidisciplinary team assessment and treatment. Baseline assessments, including demographics and Expanded Disability Status Scale (EDSS) were carried out on both groups. The primary outcome measures were Guy's Neurological Disability Scale (GNDS), and Amended Motor Club Assessment (AMCA). The secondary measures were the Barthel Index (BI), Human Activity Profile (HAP), and Short Form Item 36 Health Survey (SF-36). All measures have published data on reliability and validity. Measures were administered at one and three months. RESULTS: Forty subjects, including 27 females, completed data collection. There were no significant differences between the two groups at baseline. Results showed statistically significant differences in GNDS (p = 0.03), AMCA (p = 0.03), HAPM (p < 0.01), HAPA (p = 0.02), and BI (p = 0.02) at three months in favour of planned MDT care. CONCLUSION: This study indicates that combining steroids with planned MDT care is superior to administering them in a standard neurology or day ward setting. Further research is necessary in order to confirm this finding.

Adult↗
PubMed2003

Adipose thyrotrophin receptor expression is elevated in Graves' and thyroid eye diseases ex vivo and indicates adipogenesis in progress in vivo.

The thyrotrophin receptor (TSHR) provides an autoantigenic link between the thyroid and orbit in Graves' (GD) and thyroid eye diseases (TED). We measured TSHR transcripts in different fat depots to determine whether TSHR expression levels are influenced by the autoimmune/inflammatory process and/or thyroid hormone status, using quantitative real-time PCR. Nine intact or fractionated adipose samples, from patients with GD and/or TED, were analysed ex vivo. Eight expressed the TSHR, at levels approaching the thyroid, and one was at the limit of detection. Thirteen/fifteen orbital and abdominal fat samples from patients free of GD and TED, measured ex vivo, were negative for TSHR transcripts and two were at the limit of detection. All preadipocyte samples induced to differentiate in vitro expressed the TSHR. To investigate the influence of thyroid hormone status on adipose TSHR expression, we induced hyper- and hypothyroidism in BALBc mice by administering tri-iodothyronine and propylthiouracil respectively. In euthyroid animals, whole fat samples were at the limit of detection and were not altered by thyroid hormone status. The results show that adipose TSHR expression ex vivo indicates adipogenesis in progress in vivo and is associated with the autoimmune/inflammatory process in GD and TED but is not restricted to the orbit or influenced by thyroid hormone status.

Adipose Tissue↗
PubMed2001

A Systematic Review of the Effects of Lamotrigine on Cognitive Function and Quality of Life.

Cognitive impairment associated with antiepileptic drug (AED) therapy represents a particular problem, especially in the young and elderly. Lamotrigine (LTG) is a new-generation AED that is effective and well tolerated in both the elderly and children. Existing data suggest that the cognitive deficits commonly associated with AED therapy are not commonly observed in patients receiving LTG as monotherapy, and, when LTG is used as an add-on therapy, any existing cognitive problems are not exacerbated and in some cases are clearly improved. Here we have reviewed previous studies that have examined the impact of LTG therapy on cognitive functioning. We have considered data from monotherapy and add-on clinical studies and also more indirect evidence from volunteer studies and from neurophysiological evaluations in epilepsy patients. These data suggest that the impact of LTG on cognition is at least equivalent to that of existing standard AEDs and, in many cases, the use of LTG is associated with improved cognitive functioning, which is not seen with standard AEDs. We have also considered the wider implications of patient quality of life, accepting that cognitive function may form an integral part of the patient's perceived quality of life.

Journal Article↗
PubMed2001

Analysis of amino acids and catecholamines, 5-hydroxytryptamine and their metabolites in brain areas in the rat using in vivo microdialysis.

In vivo microdialysis, using dialysis probes inserted into discrete brain areas and subsequent analysis of neurotransmitters and related substances in the dialysates (usually with HPLC), has yielded a great deal of important information about the actions of psychotropic drugs and endogenous neurotransmitter systems and about the functional interactions between various brain areas. This paper reviews the principles involved in in vivo microdialysis, its advantages and disadvantages, and recent innovations in methodology and applications. The first section includes brief discussions of principles and applications of dialysis, use of anesthetized versus conscious freely moving animals, and methods used to determine the neural origin of neurotransmitters in the dialysate. The subsequent sections provide detailed descriptions, based largely on our own studies in rats, of stereotaxic surgery, in vivo microdialysis, and dialysate analysis, with an emphasis on amino acids and biogenic amines and their metabolites. A discussion of methodological problems which may be encountered in the analysis of amino acids and biogenic amines is also included.

Amino Acids↗
PubMed2001

Sphygmomanometer calibration: a survey of one inner-city primary care group.

Sphygmomanometers are the cornerstone of blood pressure management and yet there is no national standard for the regulation of this equipment in the UK. It is known that these machines may often be inaccurate, particularly those used in the community. We embarked upon a survey of all sphygmomanometers in current use in one inner city primary care group. Contrary to our initial hypothesis, inaccuracy rates were lower than in other reported community surveys with 2.3% of mercury and 14.8% of anaeroid sphygmomanometers failing the test. Surprisingly, inaccurate machines did not cluster in the less well developed practices. The implication is that all practices need to have procedures in place for the regular calibration of their sphygmomanometers.

Calibration↗
PubMed2000

Motion times, hand forces, and trunk kinematics when using material handling manipulators in short-distance transfers of moderate mass objects.

The risk of musculoskeletal injury associated with manual materials handling tasks has led in part to the use of material handling manipulators, yet there is limited empirical data to facilitate selection, design, and evaluation of these devices. A laboratory study of two types of mechanical manipulators (articulated arm and overhead hoist) was conducted of short-distance transfers of moderate loads, and the influence of various task parameters and transfer method on motion times, peak hand forces, and torso kinematics was obtained. Use of manipulators increased elemental motion times for symmetric sagittal plane transfers by 36-63%, and asymmetric transfers (in the frontal plane) by 62-115%, compared to similar transfers performed manually. Peak hand forces were significantly lower with both manipulators (40-50%), and approximately 10% higher for asymmetric versus symmetric transfers. Overall torso kinematics were grossly similar with and without a manipulator. These results suggest that for self-paced job tasks, moderate mass objects will be transferred slower over short distances and with lower levels of external (hand) forces when using mechanical aids. These simple effects, however, were influenced by object mass and transfer height.

Adult↗
PubMed2000

A multicenter, randomized clinical study to evaluate the effect on cognitive function of topiramate compared with valproate as add-on therapy to carbamazepine in patients with partial-onset seizures.

PURPOSE: This study compares the cognitive effects of topiramate (TPM) with those of valproate (VPA) using efficacious doses of each drug when used as adjunctive therapy to carbamazepine (CBZ). A key question of the study is to what extent a more gradual introduction of TPM improves tolerability and prevents cognitive impairment. METHODS: The study is a multicenter, randomized, observer-blinded, parallel-group clinical trial with VPA or TPM given as first-line add-on therapy to steady-state treatment with CBZ. TPM is introduced at 25 mg and increased with weekly 25mg/d increments to a minimum dosage of 200 mg/d. The target dosage ranges from 200 to 400 mg/d for TPM and is 1800 mg/d for VPA. The study evaluates cognitive function changes from baseline to end point (after 20 weeks of treatment) and during titration (after 8 weeks of treatment). The primary outcome measure is the difference between the treatments (TPM versus VPA) in change from baseline to end point and change from baseline to titration, using a 95% confidence interval approach. RESULTS: For the 10 baseline-to-end point comparisons, one test measuring short-term verbal memory (Rey Auditory Verbal Learning Test) yields a statistically significant difference between the treatments (p = 0.02), showing worsening for TPM and improvement of scores for VPA. The 10 baseline-to-titration comparisons also show one statistically significant difference, again for a test measuring short-term memory (Recognition of Words; p = 0.04), showing a larger change in the negative direction for TPM. None of the mood tests or the test for subjective complaints shows statistically significant differences between the treatments, although more scores are in the negative direction for TPM during titration. CONCLUSION: Although the pattern of changes in the negative direction seems consistent with clinical information, the differences found between the treatments are small. An important finding of our study is that, when the results are compared with those of other studies, it is clear that gradual introduction of TPM can reduce the extent of cognitive impairment (with a maximum of about 0.6 SD).

Adolescent↗
PubMed2000

Evaluation of hepatitis C virus glycoprotein E2 for vaccine design: an endoplasmic reticulum-retained recombinant protein is superior to secreted recombinant protein and DNA-based vaccine candidates.

Hepatitis C virus (HCV) is the leading causative agent of blood-borne chronic hepatitis and is the target of intensive vaccine research. The virus genome encodes a number of structural and nonstructural antigens which could be used in a subunit vaccine. The HCV envelope glycoprotein E2 has recently been shown to bind CD81 on human cells and therefore is a prime candidate for inclusion in any such vaccine. The experiments presented here assessed the optimal form of HCV E2 antigen from the perspective of antibody generation. The quality of recombinant E2 protein was evaluated by both the capacity to bind its putative receptor CD81 on human cells and the ability to elicit antibodies that inhibited this binding (NOB antibodies). We show that truncated E2 proteins expressed in mammalian cells bind with high efficiency to human cells and elicit NOB antibodies in guinea pigs only when purified from the core-glycosylated intracellular fraction, whereas the complex-glycosylated secreted fraction does not bind and elicits no NOB antibodies. We also show that carbohydrate moieties are not necessary for E2 binding to human cells and that only the monomeric nonaggregated fraction can bind to CD81. Moreover, comparing recombinant intracellular E2 protein to several E2-encoding DNA vaccines in mice, we found that protein immunization is superior to DNA in both the quantity and quality of the antibody response elicited. Together, our data suggest that to elicit antibodies aimed at blocking HCV binding to CD81 on human cells, the antigen of choice is a mammalian cell-expressed, monomeric E2 protein purified from the intracellular fraction.

Animals↗
PubMed2000

Foreign body granuloma following placement of hard tissue replacement material: a case report.

The placement of grafting material in extraction sites for ridge preservation is an increasingly common practice among clinicians. This is a case report of a patient presenting with a symptomatic, foreign body granuloma following the placement of hard tissue replacement (HTR) in extraction sockets. The surgical specimen revealed numerous histiocytes and foreign body type giant cells. The grafting material was surgically removed and the patient's symptoms were alleviated. Although biocompatibility of HTR has previously been shown, specific applications may be contraindicated or some patients may exhibit sensitivity to this material.

Alveolar Ridge Augmentation↗
PubMed1999

Mushroom body ablation impairs short-term memory and long-term memory of courtship conditioning in Drosophila melanogaster.

We have evaluated the role of the Drosophila mushroom bodies (MBs) in courtship conditioning, in which experience with mated females causes males to reduce their courtship toward virgins (Siegel and Hall, 1979). Whereas previous studies indicated that MB ablation abolished learning in an olfactory conditioning paradigm (deBelle and Heisenberg, 1994), MB-ablated males were able to learn in the courtship paradigm. They resumed courting at naive levels within 30 min after training, however, while the courtship of control males remained depressed 1 hr after training. We also describe a novel courtship conditioning paradigm that established long-term memory, lasting 9 days. In MB-ablated males, memory dissipated completely within 1 day. Our results indicate that the MBs are not required for learning and immediate recall of courtship conditioning but are required for consolidation of short-term and long-term associative memories.

Animals↗