Biomedical subjects

G Campbell

Publications and source records attributed to G Campbell.

At least 55 records · Page 3Linked to original sources

PubMed1999

Covering the CSF space: does teaching make a difference?

Following a paediatric teaching course for radiation oncology registrars which specifically addressed the method for planning cranial irradiation, a lateral skull simulation film was sent to all attendees to assess the effect of the teaching. To assess current clinical practice in New Zealand, a copy of the same radiograph was sent to radiation oncologists who had not attended the course. Recommendations from the course were that 10-mm margins should be placed in the regions of the cribiform plate and the floor of the middle cranial fossa. However, only 6.9% of the attendees marked the film with the recommended 10-mm margins. Dose profiles are also presented to support the use of 10-mm margins.

Central Nervous System Neoplasms↗

PubMed1999

Case of the month: January 1999--Fetus with echogenic mass in third ventricle.

A 29-week gestational age newborn male infant was found to have an echogenic mass in the 3rd ventricle by prenatal ultrasound 2 weeks prior to delivery. At delivery he was poorly responsive and had hydrocephalus and ascites. A CT scan after birth showed cerebral infarction, amorphous tissue in the left hemisphere and numerous calcifications. Despite supportive treatment he died 4 days after birth. Postmortem examination of the brain revealed marked distortion of the architecture and a supratentorial undifferentiated neoplasm consistent with a PNET. The tumor showed extensive areas of hemorrhage and necrosis and involvement of lateral and third ventricles, brain parenchyma, and meninges.

Brain Neoplasms↗

PubMed1999

Don't block the new kids.

Explore the source record for details and available documents.

Australia↗

PubMed1998

Cellular and molecular correlates of the regeneration of adult mammalian CNS axons into peripheral nerve grafts.

Studies of the regeneration of CNS axons into peripheral nerve grafts have provided information crucial to our understanding of the regenerative potential of CNS neurons. Injured axons in the thalamus and corpus striatum produce regenerative sprouts within a few days of graft implantation, apparently in response to living cells in the grafts. The regenerating axons often grow directly towards the grafts, and enter Schwann cell columns where they elongate surrounded by Schwann cell processes. The regenerating CNS axons, and the Schwann cell processes along which they grow, initially express the cell adhesion molecules NCAM, and L1. The axons also express polysialic acid and, unlike regenerating peripheral axons, bind tenascin-C derived from Schwann cells. Wherever peripheral nerve grafts are implanted into the CNS they appear to promote the differential regeneration of CNS axons. Most of the axons which grow into grafts in the thalamus are derived from the thalamic reticular nucleus (TRN), whereas grafts in the striatum promote regeneration of axons from the substantia nigra pars compacta (SNpc) and grafts in the cerebellum promote regeneration from deep cerebellar nuclei (DCN) and brainstem precerebellar neurons. In contrast most thalamocortical projection neurons, striatal projection neurons and Purkinje cells in the cerebellar cortex are poor at regenerating. There are patterns to the expression of regeneration-related molecules by axons injured by nerve grafts in the CNS. Most neurons which regenerate well (e.g. TRN and DCN neurons) upregulate GAP-43, L1 and the transcription factor c-jun in response to a graft, whereas those neurons which do not regenerate well (e.g. Purkinje cells, thalamocortical and striatal projection neurons) do not upregulate these molecules. These observations suggest that some classes of CNS neurons may be intrinsically unable to regenerate axons and the repair of injuries in the brain and spinal cord may consequently require some form of gene therapy for axotomised neurons.

Animals↗

PubMed1998

Axonal injury and peripheral nerve grafting in the thalamus and cerebellum of the adult rat: upregulation of c-jun and correlation with regenerative potential.

The protooncogene c-jun is highly expressed for long periods in axotomized PNS neurons. This may be related to their growth and regeneration. In contrast, axotomized CNS neurons show only a small and transient upregulation of c-jun. It has been suggested that there may be a correlation between this failure to maintain high levels of c-jun expression after axotomy and abortive CNS axonal regeneration. We have studied, by in situ hybridization and immunohistochemistry, the c-jun response after stab wound lesion, and after peripheral nerve grafting in the thalamus and cerebellum of the adult rat. A lesion elicits upregulation of c-jun in thalamic neurons ipsilateral to the lesion. This is most evident and prolonged in neurons such as those of the thalamic reticular nucleus, which have an established propensity to regenerate. After peripheral nerve grafting, the c-jun response in thalamic neurons is enhanced, mostly in neurons which have axons regenerating along the grafts. These neurons also upregulate growth-associated protein 43 (GAP-43). By comparison, injured Purkinje cells of the cerebellum which do not regenerate their axons along a graft, do not upregulate either c-jun or GAP-43, although they increase their expression of p75. Thus CNS neurons able to regenerate their axons along a peripheral nerve graft are those in which c-jun is induced after injury, and c-jun may play a critical role in the control of gene programs for axonal regeneration. Moreover, the observed differences in the ability of CNS neurons to regenerate their axons may relate to a difference in their intrinsic molecular response to axotomy.

Animals↗

PubMed1998

The identification of salicylates as normal constituents of serum: a link between diet and health?

AIM: To examine sera for the presence of salicylic acid and 2,3- and 2,5-dihydroxybenzoic acids (2,3- and 2,5-DHBA), in individuals not taking salicylate drugs. METHODS: Extracts of acidified serum samples were analysed by high performance liquid chromatography with electro-chemical detection. The chromatographic conditions were altered, and the retention times of the unknown compounds compared against authentic salicylic acid, 2,3-DHBA, and 2,5-DHBA. Serum samples (some spiked with salicylic acid) were incubated with salicylate hydroxylase and analyses undertaken. An extract of acidified serum was derivatised using N-methyl-N-trimethylsilyltrifluoroacetamide and the salicylic acid derivative identified by gas chromatography-mass spectrometry. RESULTS: Salicylic acid, 2,3-DHBA, and 2,5-DHBA were identified as being normal constituents of serum. CONCLUSIONS: Salicylic acid, 2,3-DHBA, and 2,5-DHBA possess anti-inflammatory properties. The finding that these compounds are present as normal constituents of serum, possibly arising from diet, raises important questions as to their role in the promotion of health.

Chromatography, High Pressure Liquid↗

PubMed1998

The roles of the homeobox genes aristaless and Distal-less in patterning the legs and wings of Drosophila.

In the leg and wing imaginal discs of Drosophila, the expression domains of the homeobox genes aristaless (al) and Distal-less (Dll) are defined by the secreted signaling molecules Wingless (Wg) and Decapentaplegic (Dpp). Here, the roles played by al and Dll in patterning the legs and wings have been investigated through loss of function studies. In the developing leg, al is expressed at the presumptive tip and a molecularly defined null allele of al reveals that its only function in patterning the leg appears to be to direct the growth and differentiation of the structures at the tip. In contrast, Dll has previously been shown to be required for the development of all of the leg more distal than the coxa. Dll protein can be detected in a central domain in leg discs throughout most of larval development, and in mature discs this domain corresponds to the distal-most region of the leg, the tarsus and the distal tibia. Clonal analysis reveals that late in development these are the only regions in which Dll function is required. However, earlier in development Dll is required in more proximal regions of the leg suggesting it is expressed at high levels in these cells early in development but not later. This reveals a correlation between a temporal requirement for Dll and position along the proximodistal axis; how this may relate to the generation of the P/D axis is discussed. Dll is required in the distal regions of the leg for the expression of tarsal-specific genes including al and bric-a-brac. Dll mutant cells in the leg sort out from wild-type cells suggesting one function of Dll here is to control adhesive properties of cells. Dll is also required for the normal development of the wing, primarily for the differentiation of the wing margin.

Alleles↗

PubMed1997

Diabetes-induced apoptosis in rat kidney.

Oxidative stress has been suggested to play a crucial role in the pathogenesis of diabetic complications including nephropathy. However, the exact mechanism of diabetic nephropathy is still not clearly understood. Since oxidative stress in known to be a major component in the induction of apoptosis, we investigated the occurrence of apoptosis in diabetic rat kidney. The status of oxidative stress was determined as thiobarbituric acid reactive substances (TBARS). The TBARS in the control and diabetic rat kidney were 2.00 +/- 0.963 and 3.83 +/- 0.715 mumol/mg protein, respectively (P < 0.05). Apoptosis was determined by evaluating the DNA fragmentation using an enzyme-linked immunoassay and in situ end labeling. DNA fragmentation increased approximately fourfold in diabetic rat kidney compared to the normal kidney (P < 0.05). Apoptag in situ labeling displayed negligible apoptosis in nondiabetic kidney while significant areas of apoptosis were observed in diabetic kidney. Our results suggest that increased oxidative stress in diabetic kidney could induce apoptosis, which may contribute to the development of diabetic nephropathy.

Animals↗

PubMed1997

DBT: a partial D phenotype associated with the low-incidence antigen Rh32.

Eight probands are described with a D phenotype in which a partial D antigen is associated with Rh32 antigen; three of these probands were investigated because of the anti-D in their serum. The partial D lacks epD1-epD5 and epD9 and some epD6/7 and only expresses epD8 and other parts of epD6/7. The strength of the partial D antigen varies between unrelated DBT individuals. The Rh32 antigen of the DBT cells is weaker than that of D(C)(e) cells. Tests on DBT, DFR and R0Har cells with anti-epD6/7 split these monoclonal anti-D into eight patterns of reaction. A new pattern of reactions was observed, presaging a new epitope, but this was not numbered.

Antibodies, Monoclonal↗

PubMed1997

An explanation and the clinical significance of the failure of microcolumn tests to detect weak ABO and other antibodies.

Shear forces are proposed to explain the failure of antiglobulin and 'neutral' (no antiglobulin) microcolumn tests at 37 degrees C to detect weak ABO incompatibilities and other weak antibodies, clearly detectable by spin-tube methods. These shear forces can be minimized in a microcolumn test using a biphasic centrifugation phase. Although this biphasic test is not suitable for routine use, it may be of use as an investigational method for reference laboratories. This failure of microcolumn test to detect weak ABO incompatibilities is of little clinical significance as the antibodies are dubiously active at 37 degrees C.

ABO Blood-Group System↗

PubMed1997

Which clinical features differentiate progressive supranuclear palsy (Steele-Richardson-Olszewski syndrome) from related disorders? A clinicopathological study.

The difficulty in differentiating progressive supranuclear palsy (PSP, also called Steele-Richardson-Olszewski syndrome) from other related disorders was the incentive for a study to determine the clinical features that best distinguish PSP. Logistic regression and classification and regression tree analysis (CART) were used to analyse data obtained at the first visit from a sample of 83 patients with a clinical history of parkinsonism or dementia confirmed neuropathologically, including PSP (n = 24), corticobasal degeneration (n = 11), Parkinson's disease (PD, n = 11), diffuse Lewy body disease (n = 14). Pick's disease (n = 8) and multiple system atrophy (MSA, n = 15). Supranuclear vertical gaze palsy, moderate or severe postural instability and falls during the first year after onset of symptoms classified the sample with 9% error using logistic regression analysis. The CART identified similar features and was also helpful in identifying particular attributes that separate PSP from each of the other disorders. Unstable gait, absence of tremor-dominant disease and absence of a response to levodopa differentiated PSP from PD. Supranuclear vertical gaze palsy, gait instability and the absence of delusions distinguished PSP from diffuse Lewy body disease. Supranuclear vertical gaze palsy and increased age at symptom-onset distinguished PSP from MSA. Gait abnormality, severe upward gaze palsy, bilateral bradykinesia and absence of alien limb syndorme separated PSP from corticobasal degeneration. Postural instability successfully classified PSP from Pick's disease. The present study may help to minimize the difficulties neurologists experience when attempting to classify these disorders at early stages.

Fixation, Ocular↗

PubMed1997

Frequency-dependent changes of regional cerebral blood flow during finger movements: functional MRI compared to PET.

To evaluate the effect of the repetition rate of a simple movement on the magnitude of neuronal recruitment in the primary sensorimotor cortex, we used a blood flow-sensitive, echo planar functional magnetic resonance imaging (fMRI) sequence in six normal volunteers. Three of the volunteers also had [15O]water positron emission tomography (PET) studies using the same paradigm. Previous PET studies had shown an increase in regional CBF (rCBF) with movement frequencies up to 2 Hz and then a plateau of regional cerebral blood flow (rCBF) at faster frequencies. To evaluate the extent of the activation, the correlation coefficient (cc) of the Fourier-transformed time-signal intensity change with the Fourier-transformed reference function was calculated pixel by pixel. The degree of activation was measured as the signal percent change of each region of interest with a cc > 0.5. The left primary sensorimotor cortex was constantly activated at 1, 1.5, 2, and 4 Hz, while there was only inconsistent activation at 0.25 and 0.5 Hz. Percent change in signal intensity linearly increased from 1 to 4 Hz. Area of activation increased up to 2 Hz and showed a tendency to decrease at higher frequencies. Individual analysis of PET data showed activation in the same location as that revealed by fMRI. The combination of progressively increasing signal intensity with an area that increases to 2 Hz and declines at faster frequencies explains the PET finding of plateau of rCBF at the faster frequencies. Functional magnetic resonance imaging shows similar results to PET, but is better able to dissociate area and magnitude of change.

Adult↗

PubMed1997

Optimization of noninvasive activation studies with 15O-water and three-dimensional positron emission tomography.

We investigated the effects of varying the injected dose, speed of injection, and scan duration to maximize the sensitivity of noninvasive activation studies with 15O-water and three-dimensional positron emission tomography. A covert word generation task was used in four subjects with bolus injections of 2.5 to 3D mCi of 15O-water. The noise equivalent counts (NEC) for the whole brain peaked at an injected dose of 12 to 15 mCi. This was lower than expected from phantom studies, presumably because of the effect of radioactivity outside of the brain. A 10 mCi injection gave an NEC of 92.4 +/- 2.2% of the peak value. As the scan duration increased from 60 to 90 to 120 seconds, the areas of activation decreased in size or were no longer detected. Therefore, we selected a 1 minute scan using 10 mCi for bolus injections. We then performed simulation studies to evaluate, for a given CBF change, the effect on signal-to-noise ratio (S/N) of longer scan duration with slow tracer infusions. Using a measured arterial input function from a bolus injection, new input functions for longer duration injections and the corresponding tissue data were simulated. Combining information about image noise derived from Hoffman brain phantom studies with the simulated tissue data allowed calculation of the S/N for a given CBF change. The simulation shows that a slow infusion permits longer scan acquisitions with only a small loss in S/N. This allows the investigator to choose the injection duration, and thus the time period during which scan values are sensitive to regional CBF.

Adult↗

PubMed1997