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Biomedical subjects

D Allen

Publications and source records attributed to D Allen.

At least 55 records · Page 3Linked to original sources
PubMed2001

Executive functioning in high-functioning children with autism.

Executive functioning was investigated in 34 children (24 boys and 10 girls) with developmental language disorder (DLD) and 21 children (18 boys and 3 girls) with high-functioning autistic disorder (HAD) matched on Full Scale IQ, Nonverbal IQ, age (mean age 9 year, 1 month), and SES. The DLD group had a Verbal IQ that was 10 points higher than the HAD group. These children were given the Wisconsin Card Sorting Test (WCST), the Mazes subtest from the WISC-R, the Underlining test, and the Rapid Automatized Naming test. In addition, these children were given the Vineland Scales of Adaptive Functioning and the Wing Diagnostic Symptom Checklist in order to assess severity of autistic symptomatology. Results indicated that the only significant difference between the two groups on the cognitive tasks was perseverative errors on the WCST; there was no significant difference on total number of categories achieved or total number of errors on the WCST or on the other executive function measures. There was also significant overlap in the scores between the two groups and the difference in perseverative errors was no longer significant when Verbal IQ was partialled out. Executive functioning was strongly related to all IQ variables in the DLD group and particularly related to Verbal IQ in the HAD group. Although there was a relationship in the HAD group between executive functioning and adaptive functioning, as well as between executive functioning and autistic symptomatology, these relationships were generally no longer significant in the HAD group after the variance due to Verbal IQ was accounted for. The results are interpreted to indicate that although impaired executive functioning is a commonly associated feature of autism, it is not universal in autism and is unlikely to cause autistic behaviors or deficits in adaptive function.

Autistic Disorder↗
PubMed2000

Targeted macrophage cytotoxicity using a nonreplicative live vector expressing a tumor-specific single-chain variable region fragment.

Antigen-specific recognition and subsequent destruction of tumor cells is the goal of vaccine-based immunotherapy of cancer. Often, however, tumor antigen-specific cytotoxic T lymphocytes (CTLs) are either not available or in a state of anergy. In addition, MHCI expression on tumor cells is often downregulated. Either or both of these situations can allow tumor growth to proceed unchecked by CTL control. We have shown previously that tumor antigen-specific monoclonal antibodies can be expressed in vaccinia virus and that activated macrophages infected with this virus acquire the ability to kill tumor cells expressing that antigen. Here we show that a membrane-anchored form of the scFv portion of the MUC1 tumor antigen-specific monoclonal antibody, SM3, can be expressed on activated macrophages with the highly attenuated poxvirus, modified vaccinia Ankara (MVA), as a gene transfer vector. Cells infected with the MVA-scFv construct were shown to express the membrane-bound scFv by Western blot and FACS analysis. That cells expressing the membrane-anchored scFv specifically bind antigen was shown by FACS and by BIAcore analysis. GM-CSF-activated macrophages were infected with the construct and shown to recognize specifically MUC1-expressing tumor cells as measured by IL-12 release. Furthermore, activated macrophages expressing the membrane-bound scFv specifically lyse target cells expressing the MUC1 antigen but not cells that do not express MUC1.

Animals↗
PubMed2000

Effects of steroids and retinoids on wound healing.

HYPOTHESIS: Anti-inflammatory corticosteroids significantly impair wound healing. Retinoids partially, but significantly, reverse this effect. Little is known about the mechanism of steroid retardation or retinoid reversal. We hypothesized that corticosteroids lower transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) levels and tissue deposition in wounds and that retinoids stimulate corticosteroid-impaired TGF-beta and IGF-I release and collagen production. DESIGN: Randomized controlled trial. SETTING: Wound healing research laboratory. PARTICIPANTS: Animal study. INTERVENTIONS: Four wire mesh wound cylinders were implanted subcutaneously into the backs of 72 male Sprague-Dawley rats. Wound healing was impaired by a single subcutaneous injection of 6 mg of methylprednisolone acetate (Depo-Medrol). Two preparations of retinoids were used in separate experiments: all-trans-retinoic acid and 9-cis-retinoic acid that were fed orally. MAIN OUTCOME MEASURES: Hydroxyproline content was measured in the healing tissue and TGF-beta and IGF-I levels were analyzed in the wound fluid. RESULTS: Methylprednisolone treatment significantly decreased TGF-beta and IGF-I levels in the wound fluid and hydroxyproline content in the tissue (P<.05). Oral all-trans- and 9-cis-retinoic acid partially reversed the TGF-beta and IGF-I decrease and significantly increased hydroxyproline content toward normal levels (P<.05). Oral all-trans-retinoic acid enhanced collagen deposition, TGF-beta and IGF-I levels over normal chow fed control animals (P<.05). CONCLUSIONS: Steroids and retinoids have antagonistic effects on growth factors and collagen deposition in wound healing. These effects can be relevant for treatment options in a clinical setting.

Alitretinoin↗
PubMed2000

Subgroups of children with autism by cluster analysis: a longitudinal examination.

OBJECTIVES: A hierarchical cluster analysis was conducted using a sample of 138 school-age children with autism. The objective was to examine (1) the characteristics of resulting subgroups, (2) the relationship of these subgroups to subgroups of the same children determined at preschool age, and (3) preschool variables that best predicted school-age functioning. METHOD: Ninety-five cases were analyzed. RESULTS: Findings support the presence of 2 subgroups marked by different levels of social, language, and nonverbal ability, with the higher group showing essentially normal cognitive and behavioral scores. The relationship of high- and low-functioning subgroup membership to levels of functioning at preschool age was highly significant. CONCLUSIONS: School-age functioning was strongly predicted by preschool cognitive functioning but was not strongly predicted by preschool social abnormality or severity of autistic symptoms. The differential outcome of the 2 groups shows that high IQ is necessary but not sufficient for optimal outcome in the presence of severe language impairment.

Autistic Disorder↗
PubMed2000

Lack of peripheral neuropathy in Beagle dogs after 53 weeks oral administration of thalidomide capsules.

Thalidomide (Thalomid) is approved for use in the US to treat complications from leprosy. Peripheral neuropathy is a dose-limiting adverse event in humans. As part of a nonrodent regulatory toxicology study, Beagle dogs were fed orally via encapsulation for 53 weeks. A component of this study was to determine if the dogs developed peripheral neuropathy. Twenty-eight male and 28 female Beagle dogs approximately 8-10 months of age were used. They were dosed at 43, 200 or 1000 mg/kg for 53 weeks followed by a 4-week treatment-free recovery period. Nerve function was assessed by electrophysiological measurements of the tibial nerve prior to dosing and at weeks 13, 27, 38 and 51. Representative dogs from each group were sacrificed at 26, 53 and 58 weeks and histologic and ultrastructural evaluations were performed on the sural nerve. Thalidomide had no effect on sensory nerve conduction velocity, duration or amplitude of the action potential. At 27 weeks, mean sensory nerve action potential amplitude for females at 43 mg/kg was significantly greater than control but was not evident at 39 weeks. Mean duration of sensory nerve action potential seemed to increase with similar magnitude over time in all dose groups including controls. Histological and ultrastructural evaluation of sections of sural nerve did not identify treatment-induced differences between control and thalidomide-dosed animals after 26 and 53 weeks of treatment. Additionally, no differences were observed following a 5-week treatment-free period at week 58. In contrast to humans, Beagle dogs did not develop thalidomide-induced peripheral neuropathy under conditions of the study.

Action Potentials↗
PubMed2000

Reducing antipsychotic medication in people with a learning disability.

BACKGROUND: The use of antipsychotic drugs in people with learning disabilities is currently receiving intensified scrutiny and attempts are being made to reduce it. AIMS: A randomised controlled trial was designed to investigate factors influencing antipsychotic drug reduction among people with learning disabilities prescribed such medication for behavioural problems. METHOD: Thirty-six participants randomly allocated to the experimental group underwent four, monthly 25% drug reduction stages. There were no planned drug changes for the control group (n = 20). RESULTS: Twelve participants (33%) completed full withdrawal; a further seven (19%) achieved and maintained at least a 50% reduction. Drug reduction was associated with increased dyskinesia and higher activity engagement but not increased maladaptive behaviour. Some setting characteristics were associated with drug reinstatement. CONCLUSIONS: A substantial proportion of people with learning disability prescribed antipsychotic medications for behavioural purposes rather than for treating psychotic illness can have their drugs reduced or withdrawn.

Adult↗
PubMed2000

The design and implementation of an off-the-shelf, standards-based tele-ultrasound system.

We developed an off-the-shelf system to transfer DICOM-compliant ultrasound images from a small rural hospital in northern Alberta to an urban radiology clinic in Calgary. The transfer time was less than 30 s per image. The radiologist could then review the case and release the patient. The radiologist could also switch to realtime videoconferencing mode and direct the rural ultrasound technician to obtain additional images of the patient.

Alberta↗
PubMed2000

Faculty practice: a model to bridge the theory-practice divide.

It has been suggested that as a result of nurse education withdrawing from the clinical setting and becoming established in institutions of higher education, there has been a separation of theory from practice. Recognition of the theory-practice gap by clinicians and professional bodies has led to calls for nurse educators to retain a clinical focus. Faculty practice is described and critically discussed as a model of practice to bridge the theory-practice divide. In this article, the author presents the results of a 6-month pilot study to implement such a model within a community trust, and suggests that the development of such initiatives will foster collaborative working and improve nurse education and patient care.

Attitude of Health Personnel↗
PubMed2000

Responding to aggressive behavior: impact of training on staff members' knowledge and confidence.

The impact of a training program designed to help staff members prevent and effectively manage aggressive behavior was assessed with 109 staff members who worked in services for persons with developmental disabilities. Instruction in distraction and defusion strategies was provided as was nonaggressive physical intervention. We employed both a between- and within-participant design. Results indicated that the training significantly improved participants' knowledge of reactive behavior management and their confidence to work with aggressive individuals.

Adult↗
PubMed1999

Removal of an ectopic left kidney through a ventral midline celiotomy in a calf.

A 4-month-old Holstein heifer was examined because of poor growth, weight loss, dysuria, hematuria, pyuria, and a palpable mass in the right caudal quadrant of the abdomen. Clinicopathologic abnormalities included hyperfibrinogenemia, hyperproteinemia, anemia, and leukocytosis, and were consistent with chronic inflammation. Results of ultrasonographic evaluation of the umbilical cord remnants were suggestive of urachal abscess formation. Transabdominal ultrasonography of the kidneys was attempted; the right kidney appeared normal, but the left kidney could not be imaged. The calf was anesthetized and a ventral midline celiotomy was performed. The left kidney was larger than normal, was multilobulated, and contained multiple abscess. It had also broken through the peritoneum and was located in the peritoneal cavity. Unilateral nephrectomy and resection of umbilical cord remnants were performed. The calf recovered without complications and was healthy 5 years later. In this calf, ventral midline celiotomy provided sufficient surgical exposure for removal of the ectopic left kidney and resection of umbilical cord remnants.

Animals↗
PubMed1999

A dynamic study of earthworm feeding ecology -using stable isotopes.

Changes in the specific diet of earthworms with time in relation to landuse changes and two different climates were studied by analysing (13)C and (15)N natural abundance in soils and animals. Soil samples from three depths (0-10, 10-20 and 20-30 cm) and earthworms were collected from two sites: Santiago (Northwest Spain) and North Wyke (Southwest England) both consisting of replicated long-term grasslands and recently converted to maize plots. Earthworms were hand-sorted in the field at the peak of the maize growth and after harvesting at both sites. In the Spanish plots, nine and eight earthworm species, all belonging to the three ecological categories (epigeic, anecic and endogeic), were found under maize and permanent pasture, whereas at the English site five and seven different species were, respectively, identified. At both sites (13)C isotopic values of the earthworm tissues reflected changes in diet from C(3) to C(4) with epigeic and epi/anecic worms in the maize plots showing one delta unit difference in relation to the ones found in the grassland plots. Anecic worms seemed to be less responsive to landuse changes. The higher (13)C values of the Spanish soils were also reflected in the earthworm tissues when compared with the English samples. (15)N values showed no clear relationship with the cropping treatments but were clearly related to the ecological grouping, with endogeic worms reaching the highest values whereas for the epigeic and epi/anecic species the lowest values were obtained. This finding was also previously recorded by other authors1 and suggests that, in the future, stable isotope techniques could also be a useful tool in taxonomic studies. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

Short-term changes in delta(13)C and delta(15)N signatures of water discharged from grazed grasslands

The composition of dissolved organic matter (DOM) in a soil is the product of a variety of soil processes. Changes in the composition of DOM in water discharged from soil should, therefore, give an important insight into modifications in these soil processes. We hypothesise that these processes in soils, under different grassland management regimes, would be affected to different extents by the short-term disturbance of a storm event and that evidence of this could be detected in delta(13)C and delta(15)N signatures in drainage and surface runoff waters. During a storm event we collected discharge waters from 1 ha grassland lysimeters, with or without artificial drainage, which received contrasting fertiliser inputs, and delta(13)C and delta(15)N signatures were determined. Changes in (13)C enrichment during the storm event were clearly identifiable, as were differences between plots for (13)C and (15)N, illustrating that this technique has potential to be a useful tool for identifying and investigating short- and long-term changes in soil organic matter dynamics. Copyright 1999 John Wiley & Sons, Ltd.

Journal Article↗
PubMed1999

The influences of age and caffeine on psychomotor and cognitive function.

RATIONALE: The response to caffeine is affected by a number of factors, including age. Older subjects may be more sensitive to the objective effects than younger but report fewer subjective effects. OBJECTIVE: This study assessed the influence of age on the effects of caffeine on a variety of psychomotor, cognitive and subjective tests. METHODS: Forty-eight healthy subjects, male and female, were recruited, 24 in the age range 20-25 and 24 in the range 50-65 years. All subjects were regular moderate caffeine drinkers and were not withdrawn from caffeine before entry to the study. A double-blind parallel group design was used with two groups of 12 subjects in each age range. One group in each age range received placebo and the other 250 mg caffeine B.P. A range of tests was used to assess psychomotor, cognitive and subjective functioning before and 1 h post-treatment. RESULTS: Before treatment, young subjects generally performed better than older on psychomotor and cognitive tests. On the subjective tests, however, older subjects rated themselves as more alert and less tired than the younger ones. After placebo, performance and alertness improved in the younger group but declined in the older. After caffeine there were improvements in psychomotor performance and cognitive functioning in both groups, particularly in offsetting declining performance over time in the older subjects. It also produced subjective improvements in alertness. One factor to emerge was that on most assessments older subjects were better earlier in the day whereas in younger subjects performance did not show the same magnitude of decline throughout the day. CONCLUSIONS: Caffeine induced small but significant improvements in vigilance and psychomotor performance.

Adult↗
PubMed1999

The effect of cotinine on nicotine- and cocaine-induced dopamine release in the nucleus accumbens.

Cotinine is the major metabolite of nicotine. Nicotine is rapidly metabolized and has a short half-life, but cotinine is metabolized and eliminated at a much lower rate. Because of the resulting increase with time in the cotinine to nicotine ratio in the body, including in the brain, it is of interest to examine the effect of cotinine on nicotine-induced changes. In studies on conscious, freely-moving rats, intravenous administration of either nicotine or cocaine induced the release of dopamine in the nucleus accumbens, as assayed by microdialysis. Prior intravenous administration of a high dose of cotinine (500 microg/kg) inhibited this nicotine- or cocaine-induced dopamine release. The action of cotinine does not seem to occur through its effect on the metabolism of nicotine or on its binding at the receptor site, because cotinine, unlike nicotine, does not affect the binding of the nicotinic ligand cytisine. The findings suggest that cotinine affects a putative component of the reward mechanism, and as such could have therapeutic value.

Alkaloids↗
PubMed1999

Role of FcgammaRI (CD64) in erythrocyte elimination and its up-regulation in thalassaemia.

To examine any role of the high affinity Fcgamma class I receptor (FcgammaRI) (CD64) in erythrocyte elimination by mononuclear phagocytes (MP) in thalassaemia (thal), we investigated the in vitro interaction of beta-thalassaemic erythrocytes with monocytes (Mo) whose FcgammaR expression had been modulated by cytokines. Treatment of Mo with interferon (IFN)-gamma or interleukin (IL)-10 which up-regulate FcgammaRI, caused a dose-dependent increase in binding of beta-thalassaemic erythrocytes, whereas stimulation with IL-4 which down-regulates the receptor, reduced this interaction, in a dose-dependent manner, to that of normal erythrocytes. Binding of thalassaemic erythrocytes by IFN-gamma or IL-10-treated Mo was inhibited by FcgammaRI-specific reagents. In addition, Mo expression of FcgammaRI and HLA class II DR was determined by flow cytometry in Thai patients with HbH disease (alpha1/alpha2 or alpha1/Hb Constant Spring) (n = 15) or beta degrees -thal/HbE (n = 16). In both groups of patients FcgammaRI expression was increased as compared to normal controls (n = 14): mean fluorescence intensity (+/-SD) 124.79 +/- 38. 77 in HbH disease and 121.86 +/- 18.23 in beta degrees -thal/HbE versus 91.94 +/- 17.36 in normal controls (P < 0.01 and P < 0.001, respectively). In contrast, HLA class II DR expression was similar in patients and controls. The results suggest that, in thalassaemia, up-regulated FcgammaRI on mononuclear phagocytes plays a role in their interaction with erythrocytes and that this process can be modified by cytokines.

Dose-Response Relationship, Drug↗
PubMed1999

A study of postoperative fever following paediatric tonsillectomy.

The aetiology of post-tonsillectomy fever is obscure. Bacteraemia during surgery, anaesthetic agents and the inflammatory response of tissue to injury have been implicated. A prospective study was undertaken in 100 consecutive children to evaluate the occurrence and severity of fever in the 24 h after tonsillectomy and its relationship to bacteraemia during surgery and qualitative and quantitative cultures (colony counts) of organisms in tonsil core tissue. Fifty-four patients had a fever (> 37.5 degrees C) postoperatively, of whom, 30 had a fever greater than 38 degrees C. Blood cultures during tonsillectomy were positive in 22 patients. There was no statistically significant difference between the occurrence of fever and the techniques of tonsillectomy and haemostasis. There was also no association between positive blood, core or surface cultures and the incidence or severity of fever nor any association between colony count in core cultures and fever. Our results suggest that postoperative fever in the 24 h following tonsillectomy is not caused by infection.

Adolescent↗