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Biomedical subjects

C Johnston

Publications and source records attributed to C Johnston.

At least 289 records · Page 16Linked to original sources
PubMedDate not supplied

HLA class I, II & III genes in confirmed late-onset Alzheimer's disease.

We first examined all the then known alleles (1997) at the HLA-A, B, Bw, C, DRB1, 3, 4 and 5, and DQB1 loci in 55 late-onset (>65y) AD cases and 73 elderly controls from Oxford. We found an association of HLA-B7 with late-onset AD (odds ratio = 3.1, corrected P = 0.04) that was limited to apolipoprotein E epsilon4-negative subjects (odds ratio = 5.1, corrected P = 0.005). We then studied linkages with Class III genes and, finally, we sought to replicate our HLA-B7 result in cohorts from Montreal and Nottingham. Altogether, we used 299 histopathologically confirmed cases of late-onset AD and 175 controls. Our initial, clear finding was not replicated in Montreal and Nottingham, however. We also failed to support any other previously reported association of AD with an HLA gene. Though we cannot exclude distinct linkages in different cohorts as an explanation of the conflicting results of HLA/AD studies, we conclude that there is no compelling evidence of a strong, direct association between late-onset AD and any HLA Class I or II allele.

Aged↗
PubMedDate not supplied

Lung inflammation induced by endotoxin is enhanced in rats depleted of alveolar macrophages with aerosolized clodronate.

Clodronate liposomes were given to rats via intratracheal inhalation to investigate the importance of alveolar macrophages (AMs) in inhaled endotoxin-induced lung injury. When AM depletion was maximal (87% to 90%), rats were exposed to lipopolysaccharide (LPS) or saline. Neither clodronate nor saline liposomes induced an influx of neutrophils (PMNs) into the lungs. However, depleted LPS-exposed rats had 5- to 8-fold higher numbers of lavage PMNs and greater lavage cell reactive oxygen species release compared to undepleted rats. Although AM depletion by itself did not significantly increase inflammatory cytokine expression in lung tissue, LPS-induced message levels for interleukin (IL)-1alpha, IL-1beta, IL-6, and tumor necrosis factor (TNF)-alpha were approximately 2-fold higher in AM-depleted rats compared to undepleted rats. These results indicate that cells other than AMs can recruit inflammatory cells into the lungs during acute LPS-induced injury and that AMs play an important suppressive role in the innate pulmonary inflammatory response.

Administration, Inhalation↗
PubMedDate not supplied

The efficacy of developmentally sensitive interventions and sucrose for relieving procedural pain in very low birth weight neonates.

BACKGROUND: Procedural pain management for very low birth weight (VLBW) neonates has been minimal or nonexistent in most neonatal intensive care units (NICUs). OBJECTIVES: To compare the efficacy of developmentally sensitive behavioral interventions (nonnutritive sucking via a pacifier, positioning) and sucrose for relieving procedural pain in VLBW infants and to determine the influence of contextual factors (gestational age, postnatal age, birth weight, severity of illness, frequency of painful procedures) on pain response. METHOD: In a prospective randomized crossover trial, pain was assessed in 122 VLBW neonates using the Premature Infant Pain Profile following four randomly ordered interventions during consecutive routine heel lance procedures. RESULTS: Significant differences in pain existed among treatment interventions (F = 16.20, p < .0001). The pacifier with sucrose (F = 24.09, p < .0001) and pacifier with sterile water (F = 9.00, p = .003) significantly reduced pain. Prone positioning did not decrease pain (F = 2.24, p = .137). Frequency of painful procedures approached significance in influencing pain response (F = 3.59, p = .01). CONCLUSIONS: The most efficacious interventions for reducing pain from single painful events were the pacifier with sucrose and the pacifier with sterile water. Research on the efficacy and safety of implementing these interventions, alone and in combination, for repeated painful procedures is needed. In addition, research is needed on the influence of implementing these interventions on pain response and clinical outcomes (e.g., health status and neurodevelopmental status) in VLBW neonates in the NICU.

Blood Specimen Collection↗
PubMedDate not supplied

Scintigraphic evaluation of the thoracic spine in the asymptomatic riding horse.

Scintigraphic evaluation of the spinous processes of the equine spine has been done by subjective evaluation of radiotracer uptake in clinically abnormal horses. To determine the range of variation in asymptomatic riding horses, 33 normal horses were examined. Two 60 degrees oblique views of the thoracic and lumbar spine were evaluated subjectively, and a semi quantitative method based on standardized regions of interest in each spinous process in T10-L3 was also applied. A ratio between each spinous process and a reference area (Rib 15 or 16) was calculated. The effects of two different color displays and a smoothing filter were assessed. The results of the subjective evaluation was compared to the calculated ratios, and the associations between age, gender, weight, height, use and increased radiotracer uptake, and ratios were analyzed. No significant association was found between age, gender, weight, height, use and increased radiotracer uptake, or ratio. One or more areas of increased radiotracer uptake between T13 and T18 were common in the asymptomatic riding horse, which may have implications for the interpretation of clinical patients. The blue, green and red color display had a higher sensitivity for detecting increased radiotracer uptake compared to the continuous grayscale. The smoothing filter used in this study had no effect on the detection of areas with increased radiotracer uptake. The association between the results of the subjective evaluation and the semi quantitative method was apparent when analyzed in T13-17. To evaluate if the semi quantitative method can replace the subjective evaluation, studies on clinically affected horses are necessary.

Animals↗
PubMedDate not supplied

Scintigraphy of the sacroiliac joint region in asymptomatic riding horses: scintigraphic appearance and evaluation of method.

The sacroiliac region in 33 clinically normal riding horses was examined with scintigraphy to determine the normal scintigraphic appearance, to evaluate a semiquantitative method used to calculate a sacroiliac joint (SI joint) ratio, and to identify factors that affect the scintigraphic appearance of the pelvis. The scintigraphic examination included dorsal views of each SI joint region and one lateral view of the urinary bladder. Two predefined areas (the SI joint and the area between the tuber sacrale and the SI joint) were evaluated subjectively by comparing the intensity in each area to the intensity in the tuber sacrale, and a semiquantitative method was applied on the images to calculate an SI joint ratio. The thickness of the muscle mass overlying each SI joint was measured by using ultrasound. A corrected ratio was calculated based on a corrected pixel count for each SI joint. Of 29 evaluated horses, 28 had normal radiotracer uptake in the SI joints and 10 horses had symmetric normal radiotracer uptake in the area between the tuber sacrale and the SI joint. The mean SI joint ratio was 0.53 on both the left and right sides, and the mean corrected SI joint ratio was 2.15 on the left side and 2.13 on the right side. Factors that affect the scintigraphic appearance of the pelvis were identified and included attenuation, radioactive urine, and muscle symmetry. The muscle thickness ranged from 8-11 cm, causing 71-82% attenuation. Radioactive urine in the urinary bladder was located ventral to the SI joint region in 16 horses, and four of these were excluded from further evaluation because of risk of misinterpretation. A visual assessment of symmetry of the horses' gluteal muscle mass was compared with the ultrasound measurements. Fourteen horses (14/33) were regarded symmetric by both techniques. Soft tissue attenuation was found to severely compromise the result and indicated that only lesions in the SI joint with severely increased radiotracer uptake can be detected with scintigraphy. Knowledge about presence of radioactive urine ventral to the SI joint region and assessment of muscle symmetry is essential for a correct subjective evaluation. Any situation with difference in muscle mass between the left and right side of the pelvis will give a false impression of increased radiotracer uptake on the side with lesser muscle mass.

Animals↗
PubMedDate not supplied

A preliminary report of the use of botulinum toxin type A in infants with clubfoot: four case studies.

This report describes the use of botulinum toxin type A (BTX-A) in four infants with very severe clubfoot deformity. The gastrocnemius and posterior tibial muscles were injected with BTX-A after the patients reached a treatment plateau in physical therapy. Significant improvement in foot dorsiflexion and foot flexibility was seen in two patients, and surgery was not required. Surgical intervention was necessary in the remaining two patients, both of whom were ultimately diagnosed with a demyelinating neuropathy. The use of botulinum toxin as an adjunct to conservative care in infants with clubfoot is discussed.

Anti-Dyskinesia Agents↗
PubMedDate not supplied

Is high titre ANA specific for connective tissue disease?

OBJECTIVE: A positive antinuclear antibody (ANA), while sensitive, is not specific for systemic lupus erythematosus or connective tissue diseases (CTD). The purpose of the present study was to review those sera with a high titre (> or = dilutions above screening) ANA and determine from a review of the charts if these higher titres offered a satisfactory specificity for CTD. METHODS: All FANA testing in this region is carried out in one of two related laboratories. We reviewed the medical records of patients who had a positive ANA at a titre 4 dilutions above screening at this city-wide laboratory over a 6-month period to determine whether this titre ("high titre") may offer relative diagnostic certainty. Antibodies to extractable nuclear antigens (ENA) and native DNA were also obtained. RESULTS: 422 ANA results were positive at high titre. The medical record was available for review in 320 patients, of whom 238 (75%) were seen by a specialist physician, almost always including a rheumatologist. Our review determined that 35% had a diagnosis of connective tissue disease, 21% had a diagnosis of a possible/probable inflammatory disease, 16% had an alternative specific diagnosis provided, and in 29% no final disease specific diagnosis was recorded but CTD was not suggested to us or the specialist by the data available. One or more anti-ENA antibodies and/or anti-DNA were positive in 69 (22%) and 8% of the sera tested respectively. CONCLUSION: While long term follow-up is still required, a significant proportion of patients with high titre ANA have no CTD at the time of testing. Setting a higher cutoff for reporting of ANA may not increase specificity sufficiently to make it a useful alternative or addition to reporting a positive or negative value at screening titre alone.

Adolescent↗