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G Baker

Publications and source records attributed to G Baker.

At least 19 recordsLinked to original sources
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↗
PubMed1999

Biomechanical analysis of materials handling manipulators in short distance transfers of moderate mass objects: joint strength, spine forces and muscular antagonism.

Although often suggested as a control measure to alleviate musculoskeletal stresses, the use of mechanical assistance devices (i.e. manipulators) in load transfers has not been extensively studied. Without data describing the biomechanical effects of such devices, justification for decisions regarding implementation of such tools is difficult. An experimental study of two types of mechanical manipulators (articulated arm and overhead hoist) was conducted to determine whether biomechanical stresses, and hence injury risk, would be alleviated. Short distance transfers of loads with moderate mass were performed both manually and with manipulator assistance under a variety of task conditions. Using analysis and output from new dynamic torso models, strength demands at the shoulders and low back, lumbar spine forces, and lumbar muscle antagonism were determined. Strength requirements decreased significantly at both the shoulders and low back when using either manipulator in comparison with similar transfers performed manually. Peak spine compression and anterior-posterior (a-p) shear forces were reduced by about 40% on average, and these reductions were shown to be primarily caused by decreases in hand forces and resultant spinal moments. Two metrics of muscular antagonism were defined, and analysis showed that torso muscle antagonism was largest overall when using the hoist. The results overall suggest that hoist-assisted transfers, although better in reducing spine compression forces, may impose relatively higher demands on coordination and/or stability at extreme heights or with torso twisting motions. The relatively higher strength requirements and spine compression associated with the articulated arm may be a result of the high inertia of the system. Potential benefits of practice and training are discussed, and conclusions regarding implementation of mechanical manipulators are given.

Adult↗
PubMed1999

Low-back stresses when learning to use a materials handling device.

This study examines the potential effect of short-term practice on low-back stresses during manual lifting and lowering of a 15 kg load, and while using two different types of materials handling devices (MHDs) to lift and lower a 40 kg load. The two MHDs used were an articulated balance arm and a pneumatic hoist. The expectation was that low-back dynamic moments, EMG measured torso muscle antagonism, and EMG predicted L4/L5 disc compression forces would rapidly decrease with practice, and that the manual lift-lower activities would be learned faster than the MHD-assisted exertions. Four naïve male college age subjects performed 40 lift and lower exertions, both manually and with the two MHDs for a total of 24 experiments. Non-linear regressions of the peak and average low-back moments, EMGs and disc compression values revealed only small decreases in the values (from 2 to 14%) over the 40 trials, and it was only statistically significant for five of the 48 regressions. This would seem to indicate that if learning is present in these tasks it is going to be very slow learning, and thus future studies will need to include a much larger number of trials. The effects of MHDs on the learning rates when compared to manual lifting learning rates was not statistically significant. It was shown, however, that MHDs had a particularly beneficial effect on reducing L4/L5 compression forces during load lowering activities despite the MHD load being much heavier than the manual load. It also was found that the level of torso muscle co-contraction increased significantly (2-4 times) when MHD handling was involved compared to manual lifting and lowering.

Adult↗
PubMed1999

Diabetes risk factors in low-income Mexican-American children.

OBJECTIVE: To learn if Mexican-American children from low income neighborhoods have excess diabetes risk factors. RESEARCH DESIGN AND METHODS: The study involved 173 Mexican-American children aged 9 years. This is the age before type 2 diabetes usually develops in youths and where the disparity in body fat between Mexican-American and non-Hispanic white children is evident. The study also targets poor children because diabetes and being overweight are more common in Mexican-American adults from a lower than from a higher socioeconomic status. The diabetes risk factors measured were percent body fat, dietary fat intake, daily fruit and vegetable intake, and physical fitness. Body fat was measured by bioelectric impedance, dietary intake was measured by three 24-h dietary recalls, and physical fitness was measured by a modified Harvard step test. RESULTS: According to self-reported dietary recalls, Mexican-American children ate higher than recommended fat servings and had higher percent energy from fat and saturated fat. On the other hand, their reported daily fruit and vegetable intake was half of that recommended by national dietary guidelines. A large percentage of these children were at unacceptable physical fitness levels. Percent body fat was higher in these Mexican-American children than that reported for non-Hispanic white children. Finally, 60% of the children had a first- or second-degree relative with diabetes. CONCLUSIONS: Because diabetes is highly prevalent in Mexican-American adults, type 2 diabetes in increasing in Mexican-American youths, and diabetes risk factors are more common in Mexican-American children, a prudent measure would be to explore early-age diabetes risk factor prevention programs in this population.

Adolescent↗
PubMed1998

The microlaparoscope should be used routinely for diagnostic laparoscopy.

OBJECTIVE: To describe the experience of changing from the use of the 10-mm standard laparoscope to the use of the 2-mm microlaparoscope (MicroLap, Imagyn Medical Inc., Laguna Niguel, CA) and to compare the amount of postoperative pain and requirement for analgesics after each technique. DESIGN: Prospective study. SETTING: Day surgery unit in an academic reproductive medicine unit. PATIENT(S): One hundred thirty-five women undergoing diagnostic microlaparoscopy. INTERVENTION(S): Diagnostic laparoscopy with a 2-mm instrument. Recording of postoperative pain on an analog scale. MAIN OUTCOME MEASURE(S): Ability to complete the procedure satisfactorily with the microlaparoscope, pain scores, and use of analgesics. RESULT(S): All diagnostic procedures were performed satisfactorily with the use of the MicroLap. Patients who underwent MicroLap procedures had significantly less abdominal pain postoperatively, but there was no difference in shoulder tip (gas-related) pain. Less analgesia was required after the microlaparoscopy. CONCLUSION(S): In most situations, the microlaparoscope is the instrument of choice for initial diagnostic laparoscopy. The 10-mm laparoscope should be used only as a secondary instrument after microlaparoscopy, if indicated.

Abdominal Pain↗
PubMed1998

Uptake and costs of care for epilepsy: findings from a U.K. regional study.

PURPOSE: Epilepsy is a common neurological condition, with significant resource implications for the health services, but few studies to date have examined the uptake and costs of care for this condition. As part of a large prevalence study of epilepsy conducted in one U.K. Health Region, we investigated both direct and indirect costs of epilepsy care and measured and valued the direct costs. METHODS: Data about service use were obtained from primary physician records and patient questionnaires. Unit costs for each item of resource use were generated from several sources. RESULTS: The greatest direct health care cost is that of hospital-based care. Pharmaceutical services also represent a significant element of the cost of epilepsy, the financial costs of prescribing newly developed antiepileptic drugs (AEDs) being large relative to those of the older drugs; therefore, the benefits derived from their use must be carefully assessed. The importance of good seizure control is amply illustrated by the findings about the differential costs associated with epilepsy of varying severity. The direct costs of caring for people with poorly controlled epilepsy are significant, with more than half the total cost of epilepsy care accounted for by patients with frequent seizures even though this group represented only a quarter of all patients in the present study. CONCLUSIONS: Our data emphasize the importance of optimizing seizure control as a means of reducing the costs of epilepsy, not only to the person with the condition, but also to society.

Adolescent↗
PubMed1997

Learning disability and epilepsy. 2, a review of available outcome measures and position statement on development priorities.

People with epilepsy plus learning disabilities pose a challenge in terms of clinical management and research investigation, and, to date, the measurement of outcomes in this population has been limited. There have been uncertainties concerning both the 'what' and the 'how' of assessment. This paper presents a comprehensive review of available outcome measures across nine domains, i.e. relating to seizures, drugs, cognitive function, behaviour, social functioning, carer functioning, attitudes, motivation and 'quality of life'. This last domain reflects more global measures designed to encompass several assessment strands. The uses and limitations of each scale is discussed and, where data are available, psychometric properties are also presented. The paper concludes with suggestions for the further development of outcome measures in this population.

Epilepsy↗
PubMed1997

Cumulative pregnancy rates in couples with anovulatory infertility compared with unexplained infertility in an ovulation induction programme.

Using a retrospective analysis, we compared cumulative pregnancy rates, early pregnancy failure rates and multiple pregnancy rates in couples with polycystic ovarian syndrome (PCOS) (n = 148), hypogonadotrophic or eugonadotrophic hypogonadism (n = 91) and unexplained infertility (n = 117), who were treated in an ovulation induction clinic between January 1991 and December 1995. The women were treated with either human menopausal gonadotrophin (HMG) or purified follicle stimulating hormone (FSH). The cumulative pregnancy rate (derived from life-table analysis) after four ovulatory treatment cycles was 70% in the PCOS group, 74% in the hypogonadism group and 38% in the unexplained infertility group. The cumulative pregnancy rate in the unexplained infertility group was significantly lower than the other groups (P < 0.001) but there was no significant difference between PCOS and hypogonadism using the log rank test. The early pregnancy failure rate was 25% in the PCOS group, 27% in the hypogonadism group and 26% in the unexplained infertility group (chi(2) = 0.132, not significant). The multiple pregnancy rate was 20% in the PCOS group, 30% in the hypogonadism group and 17% in the unexplained infertility group (chi(2) = 2.105, not significant). Treatment of anovulatory infertility using HMG or FSH is effective irrespective of the cause. Couples with unexplained infertility are less successfully treated using HMG: correction of unexplained infertility may involve more than simple correction of possible subtle ovulatory defects.

Adult↗
PubMed1997

Relationship between seizure frequency and costs and quality of life of outpatients with partial epilepsy in France, Germany, and the United Kingdom.

PURPOSE: The relationship between seizure frequency and both health care costs and quality of life (QOL) was investigated in a retrospective, cross-sectional, multicenter study in France, Germany, and the United Kingdom. METHODS: Three hundred outpatients with stable partial epilepsy were approximately evenly distributed among five seizure-frequency groups, ranging from seizure-free in the last 3 months (group 1) to daily seizures (group 5). Economic data, obtained through patient interviews and record abstraction, comprised direct medical costs, direct nonmedical costs, and indirect costs for the preceding 3 months. Total societal costs in the three countries were pooled and converted to United States dollar equivalents. QOL was assessed through a self-administered questionnaire, the Functional Status Questionnaire (FSQ). RESULTS: Mean total costs increased from $780 in group 1 to $2,171 in group 5 (p = 0.0001), with significant increases in each cost category as seizure frequency increased. Greater seizure frequency also significantly (p = 0.0270) correlated with lower employment rates, which ranged from 57% in group 1 to 30% in group 5. QOL declined as seizure frequency increased. Particularly affected were basic and intermediate activities of daily living (ADL), mental health, social activity, and feeling about health. CONCLUSIONS: The study results show that higher seizure frequencies are associated with higher direct and indirect costs and with reduced QOL for patients with epilepsy.

Adolescent↗