Biomedical subjects

R Campbell

Publications and source records attributed to R Campbell.

At least 55 records · Page 3Linked to original sources

PubMed2000

Exercise-induced hyponatremia in ultradistance triathletes is caused by inappropriate fluid retention.

OBJECTIVE: To study fluid and sodium balance during overnight recovery following an ultradistance triathlon in hyponatremic athletes compared with normonatremic controls. CASE CONTROL STUDY: Prospective descriptive study. SETTING: 1997 New Zealand Ironman Triathlon (3.8 Km swim, 180 Km cycle, 42.2 Km run). PARTICIPANTS: Seven athletes ("subjects") hospitalized with hyponatremia (median sodium [Na] = 128 mmol L(-1)). Data were compared with measurements from 11 normonatremic race finishers ("controls") (median sodium = 141 mmol L(-1)). INTERVENTIONS: None. MAIN OUTCOME MEASURES: Athletes were weighed prior to, immediately after, and on the morning after, the race. Blood was drawn for sodium, hemoglobin, and hematocrit immediately after the race and the following morning. Plasma concentrations of arginine-vasopressin (AVP) were also measured post race. RESULTS: Subjects were significantly smaller than controls (62.5 vs. 72.0 Kg) and lost less weight during the race than controls (median -0.5% vs. -3.9%, p = 0.002) but more weight than controls during recovery (-4.4% vs. -0.8%, p 0.002). Subjects excreted a median fluid excess during recovery (1,346 ml): controls had a median fluid deficit (521 ml) (p = 0.009). Estimated median sodium deficit was the same in subjects and controls (88 vs. 38 mmol L(-1), p = 0.25). Median AVP was significantly lower in subjects than in controls. Plasma volume fell during recovery in subjects (-5.9%, p = 0.016) but rose in controls (0.76%, p = NS). CONCLUSIONS: Triathletes with symptomatic hyponatremia following very prolonged exercise have abnormal fluid retention including an increased extracellular volume, but without evidence for large sodium losses. Such fluid retention is not associated with elevated plasma AVP concentrations.

Adult↗

PubMed2000

Developmental instability and working memory ability in children: a magnetic resonance spectroscopy investigation.

This study of children (ages 7 through 12) wishes to determine (a) whether variation in frontal lobe brain chemistry, determined from proton magnetic resonance spectroscopy (1H-MRS), is related to performance on a working memory task in children, and (b) whether developmental instability (DI; the imprecise expression of the genetic plan for development due to several known genetic and environmental effects) underlies phenotypic variation in brain chemistry. 1H-MRS assessed neurometabolites in a right frontal white matter voxel. The Visual Two-Back test assessed working memory. A composite measure of DI was created from measures of minor physical anomalies, fluctuating asymmetry of body characteristics, and fluctuating asymmetry of dermatoglyphic features. Greater DI strongly predicted lower concentrations of creatine-phosphocreatine (Cre) and choline-containing compounds, whereas Cre and N-acetyl-aspartate positively correlated with working memory skills. Working memory skills thus seem related to frontal lobe energy metabolism, which in turn is related to DI.

Aspartic Acid↗

PubMed2000

Repairing iatrogenic root perforations.

BACKGROUND: Post preparation is an integral part of restoring endodontically treated teeth in indicated cases. Iatrogenic perforation of the root can result from preparing post space and can severely compromise the prognosis of the tooth. CASE DESCRIPTION: Two years after a patient's maxillary lateral incisor was restored with a post-retained composite resin, he went to a dental school emergency clinic with a chief complaint of soft-tissue swelling adjacent to the tooth. The authors took a periapical radiograph that revealed evidence of a circumscribed radiolucent lesion associated with the distal midroot area and a periapical radiolucency. Based on the radiograph, the authors suspected that the canal preparation for the post and the post placement had perforated the root at the base of the post. CLINICAL IMPLICATIONS: The authors used a combined surgical and orthograde approach with a biocompatible restorative material and a clear, plastic light-transmitting post to repair the iatrogenic perforation.

Adult↗

PubMed1999

Response amplification in sensory-specific cortices during crossmodal binding.

Integrating information across the senses can enhance our ability to detect and classify stimuli in the environment. For example, auditory speech perception is substantially improved when the speaker's face is visible. In an fMRI study designed to investigate the neural mechanisms underlying these crossmodal behavioural gains, bimodal (audio-visual) speech was contrasted against both unimodal (auditory and visual) components. Significant response enhancements in auditory (BA 41/42) and visual (V5) cortices were detected during bimodal stimulation. This effect was found to be specific to semantically congruent crossmodal inputs. These data suggest that the perceptual improvements effected by synthesizing matched multisensory inputs are realised by reciprocal amplification of the signal intensity in participating unimodal cortices.

Adult↗

PubMed1999

Comprehensive discharge planning and home follow-up of hospitalized elders: a randomized clinical trial.

CONTEXT: Comprehensive discharge planning by advanced practice nurses has demonstrated short-term reductions in readmissions of elderly patients, but the benefits of more intensive follow-up of hospitalized elders at risk for poor outcomes after discharge has not been studied. OBJECTIVE: To examine the effectiveness of an advanced practice nurse-centered discharge planning and home follow-up intervention for elders at risk for hospital readmissions. DESIGN: Randomized clinical trial with follow-up at 2, 6, 12, and 24 weeks after index hospital discharge. SETTING: Two urban, academically affiliated hospitals in Philadelphia, Pa. PARTICIPANTS: Eligible patients were 65 years or older, hospitalized between August 1992 and March 1996, and had 1 of several medical and surgical reasons for admission. INTERVENTION: Intervention group patients received a comprehensive discharge planning and home follow-up protocol designed specifically for elders at risk for poor outcomes after discharge and implemented by advanced practice nurses. MAIN OUTCOME MEASURES: Readmissions, time to first readmission, acute care visits after discharge, costs, functional status, depression, and patient satisfaction. RESULTS: A total of 363 patients (186 in the control group and 177 in the intervention group) were enrolled in the study; 70% of intervention and 74% of control subjects completed the trial. Mean age of sample was 75 years; 50% were men and 45% were black. By week 24 after the index hospital discharge, control group patients were more likely than intervention group patients to be readmitted at least once (37.1 % vs 20.3 %; P<.001). Fewer intervention group patients had multiple readmissions (6.2% vs 14.5%; P = .01) and the intervention group had fewer hospital days per patient (1.53 vs 4.09 days; P<.001). Time to first readmission was increased in the intervention group (P<.001). At 24 weeks after discharge, total Medicare reimbursements for health services were about $1.2 million in the control group vs about $0.6 million in the intervention group (P<.001). There were no significant group differences in post-discharge acute care visits, functional status, depression, or patient satisfaction. CONCLUSIONS: An advanced practice nurse-centered discharge planning and home care intervention for at-risk hospitalized elders reduced readmissions, lengthened the time between discharge and readmission, and decreased the costs of providing health care. Thus, the intervention demonstrated great potential in promoting positive outcomes for hospitalized elders at high risk for rehospitalization while reducing costs.

Aged↗

PubMed1999

Complex patterns of intragenic polymorphism at the PDGFA locus.

The human platelet-derived growth factor A chain gene (PDGFA) on chromosome 7p22 encodes an important mitogen. Within PDGFA lies a complex minisatellite structure that results in partial duplications of exon 4 and the IVS4 splice donor site. Here, we show that the PDGFA genes of four ape species and an Old-World monkey all have similar complex minisatellites at this position. Comparison of their structures suggests evolutionary constraints resulting from the protein-coding function of the minisatellite. Nonetheless, the IVS4 minisatellite seems to have undergone independent expansion events in different primate lineages. Within the human IVS4 minisatellite, an embedded pentanucleotide repeat, based on the sequence (CCTCC)n, shows frequent subunit sequence variation but only rare length polymorphism. In contrast, within IVS3 of human PDGFA, we have discovered a second minisatellite which, unlike the IVS4 minisatellite, is highly polymorphic. The subunit sequences of these two minisatellites, which lie less than 0.5 kb apart, are non-identical, but share a CnT-rich core. Two new single nucleotide polymorphisms (SNPs), in exon 3 and IVS4, are in linkage disequilibrium, despite flanking the two minisatellite regions. Reverse transcription-polymerase chain reaction analysis of the exon 3 SNP in human foetal tissues demonstrated biallelic expression of PDGFA in all tissues examined. The unusual location of PDGFA exon 4 between two minisatellite sequences, together with its partial duplication, may have functional implications, particularly for the splicing of the gene. The high level of polymorphism demonstrated in this region will also be valuable for disease-association and linkage studies of the PDGFA locus.

Alleles↗

PubMed1999

Evaluation of midwife-led care provided at the Royal Bournemouth Hospital.

OBJECTIVE: To compare the outcome of care given to women 'booking' for delivery in a midwife-led maternity unit with that for comparable women 'booking' for care in a consultant obstetric unit. DESIGN AND METHOD: Prospective cohort study with a quasi-experimental design and data extracted from case notes. SETTING: East Dorset, midwife-led maternity unit at Royal Bournemouth Hospital and consultant-led maternity unit at Poole General Hospital. SUBJECTS: Two cohorts of women who satisfied the criteria for 'booking' at the Royal Bournemouth Hospital. Of these 794 'booked' at Bournemouth from 1 November 1992 to 30 June 1993 and 705 'booked' at Poole over the same period. MAIN PROCESS AND OUTCOME MEASURES: Care given, morbidity in women and their babies, transfers during the antenatal period and in labour. FINDINGS: Of the women who initially 'booked' for Bournemouth, 62.3% actually delivered there, 27.1% transferred before labour and a further 9.2% transferred during labour. No differences were seen between those 'booked' for Bournemouth or Poole in the proportions of low birthweight babies, babies who were transferred to special care or babies who had congenital abnormality. Higher proportions of babies whose mothers 'booked' for delivery in Poole were resuscitated and had one minute Apgar scores below seven but there was no difference in the five minute scores. Similar proportions of women had perineal tears but fewer of the women 'booked' for delivery in Bournemouth had an episiotomy. 'Booking' for Poole was associated with higher rates of induction and augmentation of labour and greater use of anesthesia. 'Booking' for Bournemouth was associated with a shorter first stage and a longer third stage of labour. Women 'booked' for delivery in Bournemouth were no more likely to be delivered by a midwife than those 'booked' for Poole. CONCLUSIONS: There was very little difference between the groups of women who initially 'booked' for delivery at the two units. There were differences in the patterns of care received, but no major differences in the outcome for the women or their babies were detected.

Adolescent↗

PubMed1999

Community services for rape survivors: enhancing psychological well-being or increasing trauma?

This research examined how contact with the legal, medical, and mental health systems affects rape survivors' psychological well-being. Although community services may be beneficial for some victims, there is increasing evidence that they can add trauma, rather than alleviate distress (termed secondary victimization). This study examined how secondary victimization affects rape survivors' posttraumatic stress (PTS) symptoms. Adaptive and snowball sampling were used to recruit a sample of 102 rape survivors. Victims of nonstranger rape who received minimal assistance from either the legal or medical system, and encountered victim-blaming behaviors from system personnel, had significantly elevated levels of PTS. This high-risk group of rape survivors had PTS levels significantly higher than all other victims in this study, including those who did not seek community assistance postrape. However, for these high-risk rape survivors, receiving sustained mental health services after these negative experiences was associated with a significant decrease in PTS.

Adolescent↗

PubMed1999

Peptidomimetic compounds that inhibit antigen presentation by autoimmune disease-associated class II major histocompatibility molecules.

We have identified a heptapeptide with high affinity to rheumatoid arthritis-associated class II major histocompatibility (MHC) molecules. Using a model of its interaction with the class II binding site, a variety of mimetic substitutions were introduced into the peptide. Several unnatural amino acids and dipeptide mimetics were found to be appropriate substituents and could be combined into compounds with binding affinities comparable to that of the original peptide. Compounds were designed that were several hundred-fold to more than a thousand-fold more potent than the original peptide in inhibiting T-cell responses to processed protein antigens presented by the target MHC molecules. Peptidomimetic compounds of this type could find therapeutic use as MHC-selective antagonists of antigen presentation in the treatment of autoimmune diseases.

Amino Acid Sequence↗

PubMed1999

Effect of a primary care based epilepsy specialist nurse service on quality of care from the patients' perspective: results at two-years follow-up.

Epilepsy specialist nurses have the potential to improve the quality of care of community-based patients with epilepsy, although evidence of their effectiveness is limited by the lack of formal or long-term evaluation. Results of a controlled trial that assessed the effectiveness of a primary care based specialist nurse-led service suggested improvements in communication and satisfaction but not health status at one-year follow-up. A second follow-up was conducted to assess the effects after two years. Patients who reported having seen the nurse at least once in the two years ('users') were compared with those who had not ('non-users'). Comparisons between users and non-users were adjusted for baseline differences. Results were based on 40% of all 595 adult patients known to have epilepsy in 14 general practices and who answered questionnaires at baseline and two years later. The new epilepsy service was used more by those with greatest needs for care. Users of the new service were significantly more likely than non-users to have discussed 8 of 11 topics asked about epilepsy [odds ratios (ORs) ranging from 2.42 to 7.91] with their general practitioner (GP), and 2 of the 11 topics with the hospital doctor (ORs 5.59, 5. 74). Service users were significantly less likely than non-users to feel their GP knew enough about epilepsy [OR 0.27, 95% confidence intervals (CI) 0.74-0.98], and significantly more likely to report epilepsy as having an adverse impact on 3 of 10 areas of everyday life (ORs ranging from 2.09 to 2.50). Users were more likely than non-users to have seen their GP for any reason in the previous year and to change their medication from use of more than one antiepileptic drug to monotherapy, although findings were not significant. Results suggest that the epilepsy specialist nurse service is not a cost-reducing substitute, particularly for general practitioner care, but it appears to improve communication and prescribing of monotherapy, and increases access for the most needy. The service may, however, have an adverse impact on patients' perceptions of the effects of epilepsy on aspects of everyday life.

Adult↗

PubMed1999

More about brows: how poses that change brow position affect perceptions of gender.

The speeded categorisation of gender from photographs of men's and women's faces under conditions of vertical brow and vertical head movement was explored in two sets of experiments. These studies were guided by the suggestion that a simple cue to gender in faces, the vertical distance between the eyelid and brow, could support such decisions. In men this distance is smaller than in women, and can be further reduced by lowering the brows and also by lowering the head and raising the eyes to camera. How does the gender-classification mechanism take changes in pose into account? Male faces with lowered brows (experiment 1) were more quickly and accurately categorised (there was little corresponding 'feminisation' of raised-brow faces). Lowering gaze had a similar effect, but failed to interact with head lowering in a simple manner (experiment 2). We conclude that the initial classification of gender from the facial image may not involve normalisation of the face image to a canonical state (the 'mug-shot view') for expressive pose (brow movement and direction of gaze). For head pose (relative position of the features when the face is not viewed head-on), normalisation cannot be ruled out. Some perceptual mechanisms for these effects, and their functional implications, are discussed.

Adolescent↗

PubMed1999

Categorical perception of face actions: their role in sign language and in communicative facial displays.

Can face actions that carry significance within language be perceived categorically? We used continua produced by computational morphing of face-action images to explore this question in a controlled fashion. In Experiment 1 we showed that question--type--a syntactic distinction in British Sign Language (BSL)--can be perceived categorically, but only when it is also identified as a question marker. A few hearing non-signers were sensitive to this distinction; among those who used sign, late sign learners were no less sensitive than early sign users. A very similar facial-display continuum between "surprise" and "puzzlement" was perceived categorically by deaf and hearing participants, irrespective of their sign experience (Experiment 2). The categorical processing of facial displays can be demonstrated for sign, but may be grounded in universally perceived distinctions between communicative face actions. Moreover, the categorical perception of facial actions is not confined to the six universal facial expressions.

Adult↗

PubMed1999

Deaf children's spelling: does it show sensitivity to phonology?

A written pictures to spelling task was given to two groups of children, 17 deaf children from signing schools (average age = 10.7) and 20 hearing children learning English as a second language (ESL, average age = 10.4). The stimuli were equally divided according to frequency, phonological regularity, and orthographic regularity. We predicted that the deaf group would not differ from the ESL group in the pattern of their responses across word classes, categorized in terms of the effect of frequency and phonological and orthographic regularity. Results showed that broadly this was the case, but more detailed analysis showed that the approach of the two groups was different. More specifically, the deaf children appeared to be sensitive to, but not aware of, phonology in their spelling, whereas the ESL group showed awareness of, as well as sensitivity to, phonology in their spelling.

Journal Article↗

PubMed1999

Managing alcohol-related problems in the primary care setting.

Although alcohol-related problems are a significant source of morbidity and mortality in the United States, denial and resistance to treatment by patients and their families make detection challenging. Primary care providers may find it difficult to confront the patient who drinks excessively; however, early intervention can lower morbidity and prevent progressive damage to family and social relationships. Routine alcohol screening of all patients may assist the primary care provider in effectively identifying and treating alcohol abuse. Although abstinence is the primary goal for patients with alcohol-related problems, decreasing intake is also beneficial and may be accomplished with brief primary care interventions. The management of outpatient alcohol detoxification is increasingly provided by primary care providers in managed care environments, but requires careful assessment of the patient's support system, close provider supervision, and appropriate pharmacologic support.

Aftercare↗

PubMed1999

Review and assessment of selection criteria used when booking pregnant women at different places of birth.

OBJECTIVE: To describe and assess the selection criteria currently being used when booking women for different places of birth. DESIGN: A cross-sectional survey. SETTING: The South and West region of England. SAMPLE: The 27 NHS Trusts who provide maternity care in the South and West region of England. MAIN MEASURES: Selection criteria used when booking pregnant women for different places of birth; length of time criteria in use; whether criteria applied individually or as part of a risk score; and method by which criteria developed. RESULTS: The response rate was 81%; 128 different, individual criteria, used as the basis to select women for different places of birth, were identified. No single criterion appeared on all the sets of criteria. None of the trusts who responded used the criteria in order to calculate a risk score. In all but one case the criteria were being used to select women who might be suitable for birth outside a consultant-led maternity unit. Only two trusts used sets of criteria which identified, to any extent, 1. outcomes for which women could be at risk and 2. strategies that should be implemented to reduce that risk. Over half the trusts were able to identify a rationale for the particular set of criteria which they used but in only two cases was any reference made to an evidence base. CONCLUSIONS: A large variety of criteria are being used as a basis on which to book women for different places of birth but they appear to be poorly focused on particular adverse outcomes. To be effective, selection criteria must identify quantifiable differences in the risk of particular preventable adverse outcomes for births booked at different locations. Furthermore, there must be evidence that the risk could be reduced by a selecting a particular location. A systematic review is required to determine which selection criteria, if any, should be employed at booking.

Adult↗

PubMed1999

Enhancing images of facial expressions.

Facial images can be enhanced by application of an algorithm--the caricature algorithm--that systematically manipulates their distinctiveness (Benson & Perrett, 1991c; Brennan, 1985). In this study, we first produced a composite facial image from natural images of the six facial expressions of fear, sadness, surprise, happiness, disgust, and anger shown on a number of different individual faces (Ekman & Friesen, 1975). We then caricatured the composite images with respect to a neutral (resting) expression. Experiment 1 showed that rated strength of the target expression was directly related to the degree of enhancement for all the expressions. Experiment 2, which used a free rating procedure, found that, although caricature enhanced the strength of the target expression (more extreme ratings), it did not necessarily enhance its purity, inasmuch as the attributes of nontarget expressions were also enhanced. Naming of prototypes, of original exemplar images, and of caricatures was explored in Experiment 3 and followed the pattern suggested by the free rating conditions of Experiment 2, with no overall naming advantage to caricatures under these conditions. Overall, the experiments suggested that computational methods of compositing and caricature can be usefully applied to facial images of expression. Their utility in enhancing the distinctiveness of the expression depends on the purity of expression in the source image.

Adult↗

PubMed1999

Secondary victimization of rape victims: insights from mental health professionals who treat survivors of violence.

Rape victims may turn to the legal, medical, and mental health systems for assistance, but there is a growing body of literature indicating that many survivors are denied help by these agencies. What help victims do receive often leaves them feeling revictimized. These negative experiences have been termed "the second rape" or "secondary victimization." If indeed secondary victimization occurs, then these issues may be raised in rape survivors' mental health treatment. In the current study, probability sampling was used to survey a representative sample of licensed mental health professionals about the extent to which they believe rape victims are "re-raped" in their interactions with social system personnel. Most therapists believed that some community professionals engage in harmful behaviors that are detrimental to rape survivors' psychological well-being. Implications for future research on secondary victimization are discussed.

Adult↗

PubMed1998

Increase in the 64-kDa subunit of the polyadenylation/cleavage stimulatory factor during the G0 to S phase transition.

The amount of the 64-kDa subunit of polyadenylation/cleavage stimulatory factor (CstF-64) increases 5-fold during the G0 to S phase transition and concomitant proliferation induced by serum in 3T6 fibroblasts. Higher levels of CstF-64 result in an increase in CstF trimer. The rise in CstF-64 occurs at a time when the amount of poly(A)-containing RNA rose at least 5-8 fold in the cytoplasm. Primary human splenic B cells, resting in G0, show a similar 5-fold increase in CstF-64 when cultured under conditions inducing proliferation (CD40 ligand exposure). Therefore, the increase in CstF-64 is associated with the G0 to S phase transition. As B cell development progresses, RNA processing changes occur at the Ig heavy chain locus resulting in a switch from the membrane- to the upstream secretory-specific poly(A) site. Treating resting B cells with agents triggering this switch in Ig mRNA production along with proliferation (CD40 ligand plus lymphokines or Staphylococcus aureus protein A) induces no further increase in CstF-64 above that seen for proliferation alone. The rise in CstF-64 is therefore insufficient to induce secretion. After stimulation of a continuously growing B cell line with lymphokines, a switch to Ig micrometer secretory mRNA and protein occurs but without a change in the CstF-64 level. Therefore, an increase in CstF-64 levels is not necessary to mediate the differentiation-induced switch to secreted forms of Ig-micrometer heavy chain. Because augmentation of CstF-64 levels is neither necessary nor sufficient for Ig secretory mRNA production, we conclude that other lymphokine-induced factors play a role.

Animals↗