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Biomedical subjects

J Ballantyne

Publications and source records attributed to J Ballantyne.

At least 19 recordsLinked to original sources
PubMed2001

Preemptive analgesia: an unsolved problem.

Preemptive analgesia studies have provided mixed results, some showing benefit and others no benefit, whereas others have shown small differences that are probably not clinically useful. There is no consensus yet about whether preemptive analgesia is a clinically useful tool. This review examines the mechanisms of preemptive analgesia before surveying the recent literature. A new definition of preemptive analgesia is proposed that accommodates the need for a broader definition. Recently published trials confirm that confusion exists about what preemptive analgesia is, how to distinguish it from simple analgesia, and how to design trials that truly assess preemptive analgesia, defined as analgesia that is capable of modifying the central excitatory responses.

Journal Article↗
PubMed1999

Transorbital optic nerve sheath ultrasonography in normal children.

AIM: Early diagnosis of acute intracranial hypertension is essential to enable prompt, optimal treatment. The optic nerve sheath diameter (ONSD) is increased in raised ICP and there has been recent interest in the use of ultrasound to diagnose and indirectly monitor raised ICP by ONSD measurement. The advantages of the technique include its non-invasiveness, wide availability, portability, low cost and the absence of ionizing radiation. This prospective study was designed to establish the range of normal values for ONSD in infants and children up to 15 years of age. PATIENTS AND METHODS: One hundred and two children attending the hospital for other reasons were recruited to the study. Three measurements of the ONSD were taken for each eye, 3 mm behind the optic nerve head using a 7 MHz sector probe. RESULTS: The range for ONSD was 2.1-4.3 mm, mean 3.08 (SD 0.36). There were no significant differences on ONSD measurement between boys and girls (P = 0.59) or between right and left eyes (P=0.66). When the data were grouped and analysed, a correlation between increasing age and increasing ONSD was seen (r2=0.48), with the greatest increase occurring in the first 2 months of life. CONCLUSION: Using the technique described here, our results suggest that an ONSD of greater than 4 mm in infants less than 1 year, and 45 mm or greater in older children, should be regarded as abnormal.

Adolescent↗
PubMed1999

Does regional anesthesia improve outcome after surgery?

The benefits and complications associated with regional anesthesia are assessed on the basis of a review of the recent literature. Benefits are separately considered as: (1) effects on hospital discharge; (2) effects on pulmonary function; (3) cardiac benefits; (4) effects on ambulation; (5) effects on metabolic stress responses; and (6) the preemptive effect. Complications reviewed are those of recent interest, and include epidural hematoma in association with anticoagulant therapy, and neural toxicity in association with high-dose local anesthetic.

Journal Article↗
PubMed1998

Efficient recombination of a switch substrate retrovector in CD40-activated B lymphocytes: implications for the control of CH gene switch recombination.

Maturing B lymphocytes possess a recombination activity that switches the class of heavy chain Ig. The nature of the recombination activity, its molecular requirements and regulation remain elusive questions about B lymphocyte biology and development. Class switch recombination is controlled by cytokine response elements that are required to differentially activate CH gene transcription before their subsequent recombination. Here, we show that cultures of purified murine and human B cells, stimulated only by CD40 receptor engagement, possess a potent switch recombination activity. CD40 ligand-stimulated murine and human B lymphocytes were infected with recombinant retroviruses containing Smu and S gamma 2b sequences. Chromosomally integrated switch substrate retrovectors (SSRs), harboring constitutively transcribed S sequences, underwent extensive recombinations restricted to their S sequences with structural features akin to endogenous switching. SSR recombination commenced 4 days postinfection (5 days poststimulation) with extensive switch sequence recombination over the next 2 to 3 days. In contrast, endogenous S gamma 2b and S gamma 1 sequences did not undergo appreciable switch recombination upon CD40 signaling alone. As expected, IL-4 induced endogenous Smu to S gamma 1 switching, while endogenous Smu to S gamma 2b fusions remained undetectable. Surprisingly, IL-4 enhanced the onset of SSR recombination in CD40-stimulated murine B cells, with S-S products appearing only 2 days postinfection and reaching a maximum within 2 to 3 days. The efficiency of switch recombination with SSRs resembles that seen for endogenous C(H) class switching.

Animals↗
PubMed1997

Antibody class switch recombinase activity is B cell stage specific and functions stochastically in the absence of 'targeted accessibility' control.

Chromosomally integrated retroviral switch (S) substrates have been developed to reveal switch recombinase-like activities (SRLA) in pre-B and mature B cell lines. Switch substrate retrovectors (SSR) contain a long-terminal repeat-driven neomycin (Neo) gene for proviral chromosomal maintenance (pre- and post-S recombination) and a CMV promoter-driven, chimeric hygromycin-thymidine kinase (Hytk) gene (flanked by S mu and S gamma 2b recombination targets) to select for (ganciclovir) and against (hygromycin B) S region recombination. The retro-substrates' strong, constitutive promoters ensure that variations in cellular switch recombinase activities are independent of S region accessibility control. By initially selecting for proviral integrants in hygromycin followed by shifting into neomycin + ganciclovir to select for S sequence-mediated deletions, switch recombinations can be specifically forestalled in B cell lines whilst most switch-incompetent cells do not survive secondary selection. A qualitative, direct PCR assay reveals that SSR recombinations are stochastic in B cell lines generating a product array akin to natural GH class switching. A semi-quantitative DC-PCR assay detects a significant recombinase activity only in a restricted set of late stage pre-B and mature B cell lines. BCL1B1 mature B cells have the highest level of recombinase activity with 25% or more of proviral integrants accumulating S mu/S gamma 2b substrate recombinations within 10-14 cell generations. The SSR recombinase assay can be performed in a transient fashion wherein extensive, B cell-specific recombination can be visualized within only a few cell divisions post proviral integration. We propose that switch recombinase activity becomes activated during B cell ontogeny independent of or prior to the acquisition of CH locus accessibility and that endogenous S segment targeting to pre-existing recombinase requires a level of accessibility beyond transcriptional activation.

3T3 Cells↗
PubMed1997

The applicability of formalin-fixed and formalin fixed paraffin embedded tissues in forensic DNA analysis.

Historically, formalin fixed (FF) tissues could not be used as a source of DNA in forensic science due to the fact that the DNA was too degraded for DNA analysis. With the introduction of the polymerase chain reaction (PCR) technique to forensic science, the usefulness of DNA from this biological material has been re-evaluated. This study evaluates the potential use of DNA from FF and formalin fixed paraffin embedded (FFPE) tissues in 13 PCR systems; HLA DQ alpha, LDLR, GYPA, HBGG, D7S8, GC, D1S80, vWA31, THO1, F13A1, FES/FPS, TPOX, and CSF1PO. The first six, HLA DQ alpha, LDLR, GYPA, HBGG, D7S8, and GC are reverse dot blot systems, D1S80 is an amplified fragment length polymorphism (AmpFlp) system and the others are short tandem repeats (STRs). This study shows that FFPE tissue which has not been fixed in formalin for more than three days is a useful source of DNA for 12 of the 13 PCR systems. In contrast, FF tissue did not prove to be a reliable source of DNA for the PCR techniques examined here.

Chelating Agents↗
PubMed1996

Cortical visual dysfunction in children: a clinical study.

Damage to the cerebral cortex was responsible for impairment in vision in 90 of 130 consecutive children referred to the Vision Assessment Clinic in Glasgow. Cortical blindness was seen in 16 children. Only 2 were mobile, but both showed evidence of navigational blind-sight. Cortical visual impairment, in which it was possible to estimate visual acuity but generalised severe brain damage precluded estimation of cognitive visual function, was observed in 9 children. Complex disorders of cognitive vision were seen in 20 children. These could be divided into five categories and involved impairment of: (1) recognition, (2) orientation, (3) depth perception, (4) perception of movement and (5) simultaneous perception. These disorders were observed in a variety of combinations. The remaining children showed evidence of reduced visual acuity and/ or visual field loss, but without detectable disorders of congnitive visual function. Early recognition of disorders of cognitive vision is required if active training and remediation are to be implemented.

Adolescent↗
PubMed1995

Forensic applications of a rapid, sensitive, and precise multiplex off lysis of the four short tandem repeat loci HUMVWF31/A, HUMTH01, HUMF13A1, and HUMFES/FPS.

A system of four short tandem repeat loci (HUMVWF31A, HUMTH01, HUMF13A1, and HUMFES/FPS) has been tested in co-amplification with forensic (post-mortem and post-coital) DNA samples. Semiautomated DNA typing was employed to analyze polymerase chain reaction (PCR) products formed by extension of primers labeled with a fluorescent dye at the 5'-terminus. Most DNA extracts could be typed, although a few required the addition of bovine serum albumin or a pretreatment by ultrafiltration in order to obtain sufficient signal for typing. Balanced signals for the alleles were obtained frequently across the loci, although preferential amplifications of HUMTH01 was observed often with the forensic samples. Band splitting due to nontemplate nucleotide addition to the blunt ends of the amplimers was frequently detected for the DNA extracted from the forensic samples. A data-base was constructed for the African-American population and compared with a Caucasian database. Few differences were observed across the two populations, except at the locus HUMTH01. The fluorescence-based system facilitates large-scale databasing, because the PCR products run off the gel, allowing more than one set of samples to be analyzed per run. Polyacrylamide gel reuse did not diminish genotyping accuracy.

Automation↗
PubMed1995

Comparison of visual assessment tests in multiply handicapped children.

The aims of this study were to compare acuity estimates achieved with visual evoked potential (VEP) and acuity card techniques and to examine the success rates of each test in a group of multiply handicapped children. Subjects were 52 children (3-183 months) with multiple handicaps associated with prematurity (n = 17), congenital anomalies (n = 16), hypoxic insult (n = 10) and other disorders (n = 9). Success rates for completing the tests were: VEP 88% and acuity cards 85% (Keeler or Cardiff). The acuity card tests were less likely to be successfully completed in the severely disabled (p < 0.05) and in those children with nystagmus (p < 0.05). When both acuity cards were successful, results agreed to within +/- 1.75 octaves. Acuity card thresholds were significantly correlated with VEP thresholds (p < 0.02), but thresholds achieved with VEPs were better in children with poor vision.

Adolescent↗
PubMed1995

A study of a dynamic proximal stability splint in the management of children with cerebral palsy.

This paper describes a study of the UPsuit, a proximal stability splint fabricated from Lycra, in the management of children with cerebral palsy. The splint improved posture and reduced involuntary movement immediately. The amount of functional improvement depended on the type and severity of impairments, the subject's attitude, their capacity for purposeful intent and compliance. Compromised lung function and pre-existing hypoactivity were medical contra-indications to UPsuit wear whilst a limited capacity for purposeful intent or a negative attitude restricted benefits. The Upsuit was of great value to one-quarter of subjects, but Lycra splinting may benefit a wider spectrum of persons with cerebral palsy in the form of less intrusive splints applied to the limbs.

Adolescent↗
PubMed1991

Tongue atrophy in mixed connective tissue disease.

A case is reported of tongue atrophy in a patient with mixed connective tissue disease (MCTD) and major myositic involvement. The case highlights oropharyngeal aspects of MCTD, including inability to wear dentures, dysarthria, and dysphagia. To our knowledge this is the first report of major tongue involvement in myositis as part of MCTD.

Deglutition Disorders↗