Assessment of muscle oxygenation in the horse by near infrared spectroscopy

This study examined the ability of near infrared spectroscopy (NIRS) to noninvasively determine changes to muscle oxygenation in the resting horse. Five horses had (NIRS) performed over extremity muscle while under general anaesthesia, first with 8 min limb ischaemia, then systemic hypoxaemia for 5 min. A second group of 6 awake horses had NIRS performed over extremity muscle while being administered hypoxic gas (F(I)O2 0.10) for 5 min, and after return to steady state, limb ischaemia was induced for an additional 5 min. In the anaesthetised horses' ischaemia induced marked and significant muscle deoxygenation of haemoglobin/myoglobin (P<0.01), with corresponding arterial saturation decreasing from 98.9 to 81.9%. Hypoxaemia induced small yet significant muscle deoxygenation (P<0.01) that was 3.2% of the ischaemia deoxygenation signal, with a corresponding decrease in arterial saturation from 98.6 to 90.4%. In the awake horses muscle deoxygenation was not detectable during hypoxia despite reduction of arterial saturation from 97.8 to 86.8%, whereas ischaemia induced rapid and significant deoxygenation of muscle (P<0.05), with corresponding reduction of venous saturation from 78.4 to 75.4%. In neither group of horses was there evidence of cytochrome aa3 reduction, despite complete ischaemia for up to 8 min. NIRS changes in the resting horse muscle clearly differed between ischaemia and hypoxaemia, and can readily show muscle deoxygenation in clinically relevant hypoxaemia in the horse under anaesthesia. Further, as the deoxygenation signal induced by ischaemia was clearly detectable above a background movement artefact, NIRS application to study of muscle oxygenation in the working horse should be explored.

Development of a protocol for the automated analysis of amino acids in brain tissue samples and microdialysates

An automated precolumn derivatisation method has been developed for the measurement of fourteen amino acids in brain tissue and microdialysate samples. The method involves labelling amino acids with naphthalene-2,3-dicarboxaldehyde (NDA) in the presence of cyanide (CN-). The resulting highly stable N-substituted 1-cyanobenz[f]isoindole (CBI) derivatives were separated using a binary gradient elution profile and detected fluorometrically. The order of elution of the derivatised amino acids was confirmed by using liquid chromatography with fluorescence and mass spectrometric detection in tandem. Linear calibration plots were obtained for all amino acids in the range studied (0.2-12.5 microM). The limit of detection for CBI derivatives of amino acids was in the range 5-20 fmol (S/N=2) using a 5 microl injection volume. The method has been used for the measurement of amino acids in microdialysates from rat brain and tissue homogenates from different regions of mouse brain.

Optical properties of human trabecular meshwork in the visible and near-infrared region

BACKGROUND AND OBJECTIVES

Despite disparate treatment parameters, similar success in laser trabeculoplasty (LT) is attained using the argon (514.5 nm) and diode (810 nm) laser. However, the mechanism of this success remains unresolved. To further understand LT, this study characterizes the optical properties of trabecular meshwork (TM).

STUDY DESIGN/MATERIALS AND METHODS

Reflectance was measured from 10 TM samples over wavelengths of 400-820 nm, using an integrating sphere/spectrophotometer. Corrections were made for reflections at boundaries of refractive index mismatch. Kubelka-Munk coefficients were calculated and converted to linear transport coefficients.

RESULTS

Scattering greatly dominated absorption. The scattering and absorption coefficients were, respectively, 141.20 +/- 15.80 cm(-1) and 4.89 +/- 1.95 cm(-1) at 514.5 nm, and 94.44 +/- 15.03 cm(-1) and 0.0874 +/- 0.111 cm(-1) at 810 nm (estimated anisotropy of 0.90). The corresponding penetration depths (1/e) were 69 microm (514.5 nm) and 106 microm (810 nm).

CONCLUSION

The absorption coefficient of 514 nm energy is two orders of magnitude greater than 810 nm energy, while scattering coefficients are much closer. The fluence used at 514.5 nm is higher at the surface than that at 810 nm, but falls below it deep within the TM due to the differential absorption. Therefore, similar initial therapeutic effects are obtained with 810 nm using less total absorbed energy. Thermal damage resultant from excess energy deposited at 514.5 nm may be related to the lack of success in repeat argon LT, pointing out the need for studies of repeat diode LT.

The implications of variation in outcome between health professionals for the design and analysis of randomized controlled trials

Methodological work on randomized trials has largely concerned pharmacological interventions in which the effects of the attending health professional may be regarded as minor. In other clinical settings, such as surgery, talk or physical therapies, staff specific variation may make generalization problematic, undermining the value of the trial. Such variation has been the basis of some objections to controlled trial methodology and non-acceptance of trial results. The implication of this source of variation will be considered for studies in which different types of health professional deliver the intervention in each arm of the trial. Such a trial may involve individual patient or group randomization. Whichever method is used, it is argued that variation in outcome between health professionals may lead to design effects. These issues will be illustrated using data from a large trial comparing primary care service delivered by two types of medical doctor. Random effect models are most suitable for analyzing this type of trial, as they allow adjustment for patient characteristics whilst controlling for design effects. This type of model illustrates that there can be substantial variation in the performance within each category of doctor.

Have we reached the therapeutic ceiling in acute myocardial infarction?

Despite the recent introduction of several new agents into the fibrinolytic market, none have proven more efficacious than earlier agents. However, new routes of administration may provide some benefit in terms of time to treatment and ease of administration. The best possibility for breaking the therapeutic ceiling is in finding new ways to use fibrinolytic agents, such as combination therapy with GP IIb/IIIa inhibitors and low-molecular-weight heparin. Use with PCI may decrease mortality rates in some patient groups. Prehospital administration of fibrinolytics is also an option for expediting care and improving outcomes.

Magma intrusion beneath long valley caldera confirmed by temporal changes in gravity

Precise relative gravity measurements conducted in Long Valley (California) in 1982 and 1998 reveal a decrease in gravity of as much as -107 +/- 6 microgals (1 microgal = 10(-8) meters per square second) centered on the uplifting resurgent dome. A positive residual gravity change of up to 64 +/- 15 microgals was found after correcting for the effects of uplift and water table fluctuations. Assuming a point source of intrusion, the density of the intruding material is 2.7 x 10(3) to 4.1 x 10(3) kilograms per cubic meter at 95 percent confidence. The gravity results require intrusion of silicate magma and exclude in situ thermal expansion or pressurization of the hydrothermal system as the cause of uplift and seismicity.

Enhancement of 5-HT1B and 5-HT1D receptor antagonist effects on extracellular 5-HT levels in the guinea-pig brain following concurrent 5-HT1A or 5-HT re-uptake site blockade

The effects of selective serotonin re-uptake inhibitor (SSRI), paroxetine, and 5-HT1A, 5-HT1B and 5-HT1B/1D receptor antagonists on in vivo extracellular 5-HT levels in the guinea-pig frontal cortex and dorsal hippocampus were investigated using the technique of microdialysis. The aim of the study was to further investigate the autoreceptor roles of the 5-HT1A, 5-HT1B and 5-HT1D receptors in the median vs dorsal raphe nuclei. In the frontal cortex, 5-HT1A (WAY 100635, 1 mg/kg i.p.) or 5-HT1B (SB-224289, 4 mg/kg i.p.) receptor antagonists had no effect on extracellular levels of 5-HT, whilst the mixed 5-HT1B/1D receptor antagonist (GR 127935, 0.3 mg/kg i.p) produced a significant decrease in extracellular 5-HT levels. Paroxetine (10 microM) significantly increased extracellular 5-HT levels when perfused locally into the cortex. Administration of SB-224289, followed 120 min later by WAY 100635, had no effect on extracellular 5-HT levels. In contrast, sequential administration of either WAY 100635 and GR 127935, or SB-224289 and paroxetine significantly increased extracellular 5-HT levels. In the dorsal hippocampus, whilst 5-HT1A receptor antagonism elicited by administration of WAY 100635 had no effect, both 5-HT1B and mixed 5-HT1B/1D receptor blockade significantly increased extracellular 5-HT levels. Administration of SB-224289 followed 120 min later with WAY 100635, or WAY 100635 followed 30 min later with GR 127935, potentiated the effect of the three compounds alone, significantly increasing extracellular 5-HT levels. These data demonstrate that to simultaneously increase extracellular 5-HT in both frontal cortex and dorsal hippocampus of the guinea-pig brain concurrent 5-HTA1A, 5-HT1B and 5-HT1D receptor blockade is required. Whereas in the dorsal hippocampus, 5-HT1B receptor blockade is sufficient to elicit an increase in extracellular 5-HT levels.

Maternal uniparental isodisomy for chromosome 14 detected prenatally

Maternal uniparental disomy (UPD) for chromosome 14 (upd(14)mat) has been associated with a distinct phenotype. We describe the first case of maternal uniparental isodisomy for chromosome 14 detected prenatally, in a pregnancy with mosaicism for trisomy 14 observed in both a chorionic villus sample (CVS) and in amniocytes. Detailed analysis of polymorphic microsatellites showed that the fetus was essentially isodisomic for one of the mother's chromosomes 14 and that recombination had introduced a mid-long arm region of heterodisomy. The fetus, which died in utero at 18 weeks, showed no apparent pathological features. The case demonstrates for the first time a maternal meiosis II non-disjunction of chromosome 14 leading to a trisomic conception which has been incompletely corrected by 'rescue' in the early embryo.

Near infrared spectroscopy in large animals: optical pathlength and influence of hair covering and epidermal pigmentation

The effects of epidermal pigmentation and hair covering on the relative transparency of various animal tissues to near infrared (NIR) light were examined, and the pathlengths of NIR light through tissues at four wavelengths in the NIR range were subsequently determined. Black hair covering and black or dark-coloured hooves prevented NIR light from penetration sufficient for conduction of pathlength or NIR spectroscopy measurements. Non-pigmented hair covering of the head did not appear to be a barrier to successful NIR light transmission. Tissues sufficiently transparent to NIR light had the differential pathlength factor (DPF, i.e. the ratio of the observed light pathlength and the geometric light source-detector separation) of NIR light determined by intensity modulated spectroscopy at the wavelengths 744, 806, 834 and 860 nm. Horse gluteal muscles had DPFs of 6.2, 6.2, 6.0, and 5.6, whereas forelimb muscles had DPF of 4.7, 4.4, 4.5 and 3.9 at the respective wavelengths. Sheep heads had DPF of 7.2 +/- 0.3, 5.8 +/- 0.5, 5.5 +/- 0.4 and 4.4 +/- 0.6 (+/- SEM) for the above respective wavelengths, of which the pathlengths all differed significantly from the other, except for between 806 and 834 nm, and 834 and 860 nm. The DPF of horse hooves were 4.8 +/- 0.1, 4.8 +/- 0.1, 4.7 +/- 0.1 and 4.4 +/- 0.1 (SEM) for the above noted wavelengths, of which the pathlength at 744 and 806 nm differed from the pathlength at 860 nm (P>0.05). These results show that NIRS is possible through lighter pigmented hair and epidermal tissues, and provide DPFs of horse feet and muscle and the sheep head that enables quantitative NIRS in these species

The Wisdom Project: virtual education in primary care

This article examines the development of the Wisdom Project, a pilot for the teaching of informatics to primary health care professionals, using an original educational model based on e-mail and Web pages. The article begins by placing the development of the Wisdom Project in the context of changes in medical education and training. The aims and objectives of Wisdom are outlined, and the methodologies for setting up and evaluating the project are described. The article then presents the results of the evaluation, including the identification of significant improvements in knowledge of CD ROMs (P = 0.01), e-mail (P = 0.03), Medline (P = 0.02), operating systems (P = 0.02), Web browsers (P = 0.003) and word processing (P = 0.03). Improvements in evidence-based practice (EBP) did not reach significance. Finally, a number of conclusions are presented, considering the lessons learnt for the future development of such projects.

Modelling method comparison data

We explore a range of linear regression models that might be useful for either: (a) the relative calibration of two or more methods or (b) to evaluate their precisions relative to each other. Ideally, one should be able to use a single data set to carry out the jobs (a) and (b) together. Throughout this review we consider the constraints (assumptions) needed to attain identifiability of the models and the possible pitfalls to the unwary in having to introduce them. We also pay particular attention to the possible problems arising from the presence of random matrix effects (reproducible random measurement 'errors' that are characteristic of a given method when being used on a given specimen or sample, i.e. specimen specific biases or subject by method interactions). Finally, we stress the importance of a fully-informative design (using replicate measurements on each subject using at least three independent methods) and large sample sizes.

The WISDOM project: training primary care professionals in informatics in a collaborative 'virtual classroom'

OBJECTIVES

The WISDOM project applies Internet technologies to create a virtual classroom in health informatics for primary care professionals. Participants use a facilitated E-mail discussion list supported by a web site which provides on-line resources and an archive of teaching materials.

DESIGN

The project took an adult-learning model in which participants identify their learning needs, emphasized using informatics skills in practice, and focused on skills likely to enhance evidence-based practice. The paper describes the project and an evaluation of the first programme which ran in 1997 with 28 participants. Pre- and post-intervention questionnaires were used to assess perceived skills in informatics and evidence-based practice.

SETTING

University of Sheffield.

SUBJECTS

Primary care professionals.

RESULTS

Participants reported statistically significant increases in eight informatics skills. There were no significant changes in evidence-based practice skills. The web-site, seminar programme and discussion list were highly rated as useful in delivering informatics training.

CONCLUSIONS

The WISDOM approach is effective for the delivery of informatics training to primary care professionals, and may be used more widely for other subjects and professional groups. There is a need for further research into facilitating virtual classrooms.

Retention of young general practitioners entering the NHS from 1991-1992

BACKGROUND

The supply of general practitioners (GPs) in the National Health Service (NHS) is dynamic and there are fears that there will be an inadequate number of doctors to meet the needs of the NHS. There are particular concerns about changes in the career trajectory of young GPs and what they mean for overall supply.

AIM

To identify predictors of retention among young, new entrant GPs entering the NHS between 1 October 1991 and 1 October 1992.

METHOD

Two-year retention rates of young (35 years of age or less) new entrant GPs have been modelled using a multilevel logit model. Retention is defined as young, new entrant GPs remaining in their initial health authority for two years or more.

RESULTS

Two hundred and fifty-two (13.0%) members of the study group left general practice within two years of entry (i.e. were not retained). Sex (females had lower retention [95% CI = 0.43-0.75]), practice size (young GPs in larger practices had higher retention [95% CI = 1.10-1.29]), and belonging to a practice in one of 16 Greater London Health Authorities (which had lower retention [95% CI = 0.39-0.82]) were identified as major predictors of retention. Deprivation, measured at the individual GP patient list level, had a very slight association with retention (P = 0.097; 95% CI = 1.00-1.02). Deprivation measured at the health authority level (95% CI = 0.99-1.01) was not found to be a statistically significant predictor of retention (P = 0.83).

CONCLUSION

None of the statistically significant predictors of retention suggest any policy panacea to end this phenomenon. The challenge for policy is to learn to deal with the dynamic nature of the GP workforce with a non-crisis mentality.

Is follow up by specialists routinely needed after elective surgery? A controlled trial

STUDY OBJECTIVE

To assess the benefit of planned specialist follow up appointments after elective inpatient surgery.

DESIGN

This was a controlled trial, using repeated alternate allocation of time periods to the two study groups. Group 1: Planned outpatient follow up 6-12 weeks after surgery. Group 2: No planned follow up: additional written information for patients and general practitioners.

SETTING

A district general hospital in the north west of England.

PARTICIPANTS

264 patients listed for one of: transurethral resection of the prostate, varicose vein surgery, cholecystectomy (open or laparoscopic), inguinal herniorraphy (open or laparoscopic).

MAIN OUTCOME MEASURES

Health status, complications, return to normal activity, patient satisfaction, use and costs of primary and secondary care in the 12 weeks after surgery.

MAIN RESULTS

Data were available for 212 (80%) of eligible patients. Thirty eight per cent of patients in the "no planned follow up" group were in fact seen in outpatients after their discharge. Intention to treat analysis showed that there were no significant differences between the groups for health status, complications, or time to return to normal activity. Patients in the "no planned follow up" group had significantly fewer hospital visits and costs (mean difference in visits 0.51, 95% confidence intervals 0.39 to 0.69; mean difference in hospital costs 12.75 Pounds, 9.75 Pounds to 15.50 Pounds). There were fewer primary care staff contacts and costs in the "no planned follow up" group, although this difference was not significant (mean difference = 0.61 visits, -0.13 to 1.33 visits; primary care costs difference 8.37 Pounds, -1.31 Pounds to 18.73 Pounds). Patients in the "no planned follow up group" had significantly reduced patient travel costs (mean difference 4.84 Pounds, 3.44 Pounds to 6.22 Pounds). Eighty nine (42%) patients would prefer to be followed up by both their hospital doctor and GP; 53 (25%) patients would prefer to be followed up by the hospital doctor only. There were no significant differences between the two groups in their preferences for follow up. The majority of GPs agreed with the statement that a policy of no follow up at hospital outpatients for each of the six surgical procedures would increase their workload.

CONCLUSIONS

Planned outpatient appointments after uncomplicated surgery seem to be neither necessary nor cost effective. A policy of "no planned follow up" results in no increase in primary care costs, and savings in hospital and patient costs. However, many patients expected and wanted to be seen again by their surgeon and GPs were concerned that a "no follow up" policy would result in an increase in workload.

The assessment and treatment of deaf children with psychiatric disorders

The assessment and treatment of deaf children with psychiatric disorder is intimately related to the individual child's communication, which in turn is affected by a number of factors, medical, social, and cultural. The deafness can be aetiologically related to the psychiatric disorder or can be incidental. Treatment strategies should be adapted to meet the individual child and family's needs. Deaf professionals have a vital role in mental health services for this population. The use of an interpreter can clarify communication and cultural issues for deaf and hearing children, families, and professionals.

The continuing evolution of methicillin-resistant Staphylococcus aureus in Western Australia

Methicillin-resistant Staphylococcus aureus (MRSA) has been notifiable in Western Australia since 1985. This article reviews the notification data from 1994 to 1997, focusing on increases in MRSA notifications and the proportion that are local strains; changes in the geographical distribution of MRSA; and changes in antibiotic-resistance patterns.

Clinical significance of an extensor tendon anomaly to the little finger--a new finding

A new anatomical variation of extensor digiti minimi (EDM) was discovered during our anatomical studies. The EDM usually gives one tendon to the little finger to extend the metacarpophalangeal joint (MPJ) independently from the other fingers. The EDM in our cadaver had three tendon slips. It supplied the MPJ of the little finger with two tendon slips. Along with the extensor digitorum communis (EDC), the EDM also had an additional slip to the ring finger MPJ extensor hood apparatus. The little finger also received a separate tendon from EDC.

Effect of irradiation with a low-intensity diode laser on the metabolism of equine articular cartilage in vitro

OBJECTIVE

To determine whether irradiation with a low-intensity diode laser, which produces radiation at a wavelength of 810 nm, will induce nonthermal enhancement of chondrocyte metabolism.

SAMPLE POPULATION

144 grossly normal articular cartilage explants aseptically harvested from the femoral condyles of 6 adult horses.

PROCEDURE

Treated cartilage explants were irradiated with a diode laser at 1 of 7 fluence levels that ranged from 8 to 1,600 J/cm2. Explants were incubated for 24 or 72 hours, labeled for 24 hours with [35S]Na2SO4, and assayed for newly synthesized sulfated glycosaminoglycan (GAG; measured incorporation of 35SO4) and endogenous GAG, chondroitin 6-sulfate (CS), and keratan sulfate (KS) content, using a dimethylmethylene blue assay. Laser-induced temperature changes were measured during irradiation with a diode laser and a neodymium:yttrium aluminum garnet (Nd:YAG) laser, which produces radiation at a wavelength of 1,064 nm, using conditions that were reported in previous studies to increase explant metabolism.

RESULTS

After incubation for 24 or 72 hours, rate of 33SO4 uptake or endogenous GAG, CS, or KS content in irradiated explants was not significantly different than in nonirradiated explants. Cartilage temperature increased < 4.75 C during diode laser application. Cartilage temperature increased 5 to 12 C during Nd:YAG laser application.

CONCLUSIONS

Minimal thermal increases in cartilage explants with use of a low-intensity diode laser resulted in no change in proteoglycan metabolism of chondrocytes. An increase in tissue temperature over a narrow range with use of a Nd:YAG laser may have contributed to the metabolic alteration of chondrocytes reported in previous studies.