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Biomedical subjects

W A Wallace

Publications and source records attributed to W A Wallace.

At least 37 records · Page 2Linked to original sources
PubMed2001

The management of osteoporosis.

Osteoporosis poses a significant orthopaedic problem of epidemic proportions. Clear guidelines for the management of osteoporosis presenting early or late are still being debated. Several recommendations, however, are now generally accepted. Measurements of BMD should be taken if the diagnosis is in doubt or as an adjunct to encourage patient compliance with treatment. Those with multiple risk factors and who are under the age of 65 years would benefit from a scan. Those with previous fractures and no obvious risk factors should also be sent for DXA assessment. The elderly with fractures and multiple risk factors do not need scanning and can normally be started on treatment. Mass population screening is not cost-effective. Prevention strategies should be targeted at high-risk patients and not offered to everyone. In the perimenopausal woman HRT is the first line of treatment and prevention, along with changes in lifestyle. Tibolone may be an option for those who find cyclical bleeding unacceptable. In the elderly, institutionalised patient, calcium and vitamin-D supplements should be considered to replace depleted levels, particularly for secondary prevention. Postmenopausal women with multiple risk factors and at least one insufficiency fracture should be treated. The most likely pharmacological agent will be a bisphosphonate with supplemental calcium if indicated. Each hospital should have a recognised link person through whom referrals can be channelled, either a clinical nurse specialist or physician. A protocol for treatment should be agreed locally and publicised among the primary health-care groups. The first step of identification of high-risk patients is most often in fracture clinics. Standardised letters attached to the clinic note to general practitioners are an easy way of 'getting these patients into the system'.

Female↗
PubMed2001

Outcomes in post-ICU mechanical ventilation: a therapist-implemented weaning protocol.

BACKGROUND: Therapist-implemented protocols have been used to extubate or wean patients in the ICU setting. Barlow Respiratory Hospital (BRH) functions as a center for weaning patients from prolonged mechanical ventilation (PMV) in the post-ICU setting of a long-term acute-care (LTAC) facility. A therapist-implemented patient-specific (TIPS) weaning protocol was developed at BRH to standardize weaning from PMV. STUDY DESIGN: Prospective cohort study with historical control. METHODS: A weaning protocol incorporating the procedures and pace of LTAC weaning was developed using available scientific evidence and expert consensus. After training of staff, collection and analysis of pilot data, and revisions and refinement of the protocol, the TIPS protocol was implemented hospital-wide. It was monitored for outcome, variance, and respiratory care practitioner (RCP) and physician compliance. RESULTS: Forty-six RCPs worked with eight pulmonologists treating 271 consecutive patients admitted for weaning from PMV during an 18-month period. Nineteen patients were excluded from weaning attempts by any method after initial physician evaluation. The remaining 252 patients (9,135 total ventilator days) were compared with a group of 238 patients treated by the same physicians in the 2 years before instituting protocol weaning. Median time to wean declined significantly from 29 days in historical control subjects to 17 days for TIPS protocol patients (p < 0.001). Outcomes (scored at discharge) were comparable for the two groups (TIPS group vs control group): weaned, 54.7% vs 58.4%; ventilator-dependent, 17.9% vs 10.9%; died, 27.4% vs 30.7% (p = 0.10). Variances incurred by physicians and RCPs were 324 and 136, respectively, for the 9,135 ventilator days. CONCLUSIONS: Patients weaned from PMV using a new therapist-implemented protocol at BRH, an LTAC facility specializing in weaning, had significantly shorter time to weaning than historical control subjects, with comparable outcomes. The weaning outcome data collected after the implementation of the TIPS protocol are in fact attributable to its use, as we found a high degree of compliance with the protocol.

Aged↗
PubMed1999

Immunoreactive interleukin 4 and interferon-gamma expression by type II alveolar epithelial cells in interstitial lung disease.

Cryptogenic fibrosing alveolitis (CFA), extrinsic allergic alveolitis (EAA), and sarcoid are all immunologically mediated forms of interstitial lung disease. In contrast to most patients with EAA and sarcoid, patients with CFA show relentless pulmonary fibrosis which is unresponsive to immunosuppressive therapy. Previous studies have indicated a possible role for epithelial-derived cytokines in the regulation of immunological and fibrotic responses in the lung. This study has examined lung biopsy specimens from patients with CFA, EAA, and sarcoid for immunoreactive interleukin 4 (IL4) and interferon-gamma (INFgamma) expression by type II alveolar epithelial cells, as these cytokines have been suggested to have in vitro stimulatory and inhibitory effects on fibroblast function. In addition, mRNA in situ hybridization was performed on the CFA lung biopsies to confirm transcription of these cytokine genes within the cells. The results show that type II epithelial cells in EAA and sarcoid show up-regulation of immunoreactivity for both IL4 and INF-gamma, but that in CFA only IL4 is detectable. The mRNA in situ hybridization results indicate that this may represent post-transcriptional regulation of INFgamma expression in CFA. These results are consistent with previous observations of a paucity of INFgamma and a predominantly type II (Th2-like) pattern of immune response in patients with CFA and suggest a possible imbalance of pro-fibrogenic cytokines in the distal lung of patients with this condition, compared with those with EAA or sarcoid.

Aged↗
PubMed1999

CT imaging and three-dimensional reconstructions of shoulders with anterior glenohumeral instability.

Glenohumeral instability is a common occurrence following anterior dislocation of the shoulder joint, particularly in young men. The bony abnormalities encountered in patients with glenohumeral instability can be difficult to detect with conventional radiography, even with special views. The aim of our study was to evaluate the bony abnormalities associated with glenohumeral instability using CT imaging with 3-D reconstruction images. We scanned 11 patients with glenohumeral instability, one with bilateral symptoms; 10 were male, one female, and their ages ranged from 18-66 years. Contiguous 3 mm axial slices of the glenohumeral joint were taken at 2 mm intervals using a Siemens Somatom CT scanner. In the 12 shoulders imaged, we identified four main abnormalities. A humeral-head defect or Hill-Sachs deformity was seen in 83% cases, fractures of the anterior glenoid rim in 50%, periosteal new bone formation secondary to capsular stripping in 42%, and loose bone fragments in 25%. Manipulation of the 3-D images enabled the abnormalities to be well seen in all cases, giving a graphic visualization of the joint, and only two 3-D images were needed to demonstrate all the necessary information. We feel that CT is the imaging modality most likely to show all the bone abnormalities associated with glenohumeral instability. These bony changes may lead to the correct inference of soft tissue abnormalities making more invasive examinations such as arthrography unnecessary.

Adolescent↗
PubMed1999

Late repair of simultaneous bilateral distal biceps brachii tendon avulsion with fascia lata graft.

A 50 year old rock climber sustained a bilateral rupture of the distal biceps brachii tendons. He retained some flexion power in both arms but minimal supination, being weaker on the non-dominant right side. As the patient presented late, with retraction and shortening of the biceps muscle bellies, reconstruction was carried out using fascia lata grafts on both sides. Because of residual weakness on the left (dominant) side, three further surgical procedures had to be carried out to correct for elongation of the graft. A functionally satisfactory outcome, comparable with that on the right side, was eventually obtained. In summary, bilateral fascia lata grafts to bridge the gap between the retracted biceps bellies and the radial tuberosities were successful in restoring function and flexion power to the elbow. Despite being the stronger side, the dominant arm did not respond as well to the initial surgery. This may be due to overuse of this arm after the operation.

Arm Injuries↗
PubMed1999

Hypersensitivity pneumonitis associated with co-proxamol (paracetamol + dextropropoxyphene) therapy.

A 61-year-old man developed hypersensitivity pneumonitis and skin rash in close association with taking co-proxamol. These problems occurred in spite of being treated with prednisolone 40 mg daily (20 mg daily at the time of presentation) for assumed cranial arteritis. A therapeutic challenge with paracetamol was negative and the patient continues to take this drug. It seems likely that this patient's rash and hypersensitivity pneumonitis was caused by dextropropoxyphene. Dextropropoxyphene has not been reported previously as a cause of hypersensitivity pneumonitis.

Acetaminophen↗
PubMed1998

The mechanism of femoral fracture in an impact accident.

BACKGROUND: Following the crash of a Boeing 737-400 aircraft on the M1 motorway at Kegworth, near Nottingham, England, on January 8, 1989, it became apparent that a large number of pelvic and lower limb injuries had been sustained by the survivors. Had there been a fire, these injuries would have severely hindered the ability of the occupants to escape. The mechanism of pelvic and lower limb injuries in impact accidents previously has been related to flailing of the limbs and axial loading of the femur as in automobile accidents. HYPOTHESIS: A bending load is the primary mechanism of femoral fracture in an impact aircraft accident rather than an axial load. METHODS: Two methods of study have been used to investigate the impact biomechanics of the pelvis and lower limb: a) clinical review of the injuries sustained in the M1 Kegworth accident; and b) impact testing. RESULTS: A clinical review of the M1 aircrash survivors suggested that axial loading was not the primary mechanism causing femoral fractures and suggested that a bending load might be applied to the femur. Impact testing confirmed that axial loading of the femur did not appear to be significant. CONCLUSIONS: Our study suggests that in the presence of intact occupant protection systems, a femoral bending mechanism involving the front seat spar of passenger seats is a primary cause of femoral fracture in an impact aircraft accident.

Accidents, Aviation↗
PubMed1998

A modified crash brace position for aircraft passengers.

BACKGROUND: In 1989, a Boeing 737-400 aircraft crashed at Kegworth, near Nottingham, England. The survivors suffered a large number of pelvic and lower limb injuries, and approximately one-third of the passengers died. Subsequent research has suggested that the "brace-for-impact" position that passengers are advised to adopt prior to a crash landing might be modified in order to reduce the incidence of such injuries. The aim of this research was to evaluate biomechanically such a modified crash brace position. HYPOTHESIS: A modified brace position would help to prevent injuries to some passengers in the event of an impact aircraft accident. METHODS: Impact testing on forward-facing seats was performed at the Royal Air Force Institute of Aviation Medicine, Farnborough, England. Aircraft seats, mounted on a sled, were propelled down a track to impact at -16 Gx. A test dummy was used as the experimental model. Four dummy positions were investigated: a) upper torso braced forward and lower legs inclined slightly rearward of the vertical; b) upper torso braced forward and lower legs inclined forward; c) upper torso upright and lower legs inclined slightly rearward of the vertical; and d) upper torso upright and lower legs inclined forward. The impact pulses used were based on Federal Aviation Administration guidelines. Transducers located in the head, spine, and lower limbs of the dummy recorded the forces to which each body segment was exposed during the impact. These forces were compared for each brace position. RESULTS: Impact testing revealed that the risk of a head injury as defined by the head injury criterion was greater in the upright position than in the braced forward position. The risk of injury to the lower limbs was dependent in part on the flailing behavior of the limbs. Flailing did not occur when the dummy was placed in a braced, legs-back position. CONCLUSIONS: A modified brace position would involve passengers sitting with the upper torso inclined forward so that the passenger's head rested against the structure in front, if possible. The legs would be positioned with the feet resting on the floor in a position slightly behind the knee. The position differs from those previously recommended in that the feet are positioned behind the knee. This study suggests that such a position would reduce the potential for head and lower limb injury in some passengers, given that only a single seat type and single size of occupant have been evaluated. Standardization to such a position would improve passenger understanding and compliance. Such a recommendation should not obscure the fact that an occupant seated in a forward-facing aircraft seat, restrained only by a lap belt, is exposed to considerable forces during an impact accident. Such forces are capable of producing injuries in the femur, pelvis, and lumbar spine.

Accidents, Aviation↗
PubMed1997

Regulatory role for macrophage migration inhibitory factor in acute respiratory distress syndrome.

Migration inhibitory factor (MIF) is known to exert significant pro-inflammatory effects and has the potential to override the anti-inflammatory action of glucocorticoids. In this study we have identified significant quantities of MIF in the alveolar airspaces of patients with acute respiratory distress syndrome (ARDS). We show in alveolar cells from patients with ARDS that MIF augments pro-inflammatory cytokine secretion (TNF alpha and IL-8), anti-MIF significantly attenuates TNF alpha and IL-8 secretion and MIF overrides, in a concentration-related fashion, the anti-inflammatory effects of glucocorticoids. These findings suggest that MIF may act as a mediator sustaining the pulmonary inflammatory response in ARDS and that an anti-MIF strategy may represent a novel therapeutic approach in inflammatory diseases such as ARDS.

Cells, Cultured↗
PubMed1997

Evidence for safety and efficacy of DOTAP cationic liposome mediated CFTR gene transfer to the nasal epithelium of patients with cystic fibrosis.

In cystic fibrosis (CF), mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene results in defective transepithelial ion transport, leading to life shortening inflammatory lung disease. Before lung studies, we tested the safety and efficacy of gene delivery to the nasal epithelium of CF patients using pCMV-CFTR-DOTAP cationic liposome complex. A single dose of 400 micrograms pCMV-CFTR:2.4 mg DOTAP was administered in a randomised, double-blinded fashion to the nasal epithelium of eight CF patients, with a further eight receiving buffer only. Patients were monitored for signs and symptoms for 2 weeks before treatment and 4 weeks after treatment. Inflammatory cells were quantified in a nasal biopsy taken 3 days after treatment. There was no evidence for excess nasal inflammation, circulating inflammatory markers or other adverse events ascribable to active treatment. Gene transfer and expression were assayed by the polymerase chain reaction. Transgene DNA was detected in seven of the eight treated patients up to 28 days after treatment and vector derived CFTR mRNA in two of the seven patients at +3 and +7 days. Transepithelial ion transport was assayed before and after treatment by nasal potential difference during drug perfusion and by SPQ fluorescence halide ion conductance. Partial, sustained correction of CFTR-related functional changes toward normal values were detected in two treated patients. The level of gene transfer and functional correction were comparable to those reported previously using adenoviral vectors or another DNA-liposome complex, but here were sustained and uncompromised by false positives. These results justify further studies with pCMV-CFTR-DOTAP aimed at treating CF lung disease.

Adult↗
PubMed1997

The relationship between three-dimensional imaging and group decision making: an exploratory study.

This paper describes an empirical investigation of the effect of three dimensional (3-D) imaging on group performance in a tactical planning task. The objective of the study is to examine the role that stereoscopic imaging can play in supporting face-to-face group problem solving and decision making-in particular, the alternative generation and evaluation processes in teams. It was hypothesized that with the stereoscopic display, group members would better visualize the information concerning the task environment, producing open communication and information exchanges. The experimental setting was a tactical command and control task, and the quality of the decisions and nature of the group decision process were investigated with three treatments: 1) noncomputerized, i.e., topographic maps with depth cues; 2) two-dimensional (2-D) imaging; and 3) stereoscopic imaging. The results were mixed on group performance. However, those groups with the stereoscopic displays generated more alternatives and spent less time on evaluation. In addition, the stereoscopic decision aid did not interfere with the group problem solving and decision-making processes. The paper concludes with a discussion of potential benefits, and the need to resolve demonstrated weaknesses of the technology.

Analysis of Variance↗
PubMed1997

Traumatic occlusion of the external iliac artery in a racing cyclist: a cause of ill defined leg pain.

Stenosis of the external iliac artery in healthy athletes, although uncommon, has been reported in competition cyclists. A case of a racing cyclist whose chronic vague leg symptoms were incorrectly attributed to L4/5 nerve root irritation is reported. This highlights the importance of clinical vascular testing when assessing ill defined leg pain. The role of trauma as a causative factor in this condition has not been previously documented.

Adult↗
PubMed1997

Early femoral loosening in one design of cemented hip replacement.

We have studied aseptic loosening of the femoral component in 76 patients with primary total hip replacement using the Capital prosthesis. The mean follow-up was 26 months (10 to 37). Twelve femoral components (16%) were definitely and eight (10%) were possibly loose. They were characterised by a thin cement mantle (p < 0.001) and excessive residual cancellous bone in the proximomedial region (p < 0.01). We recommend that the cement mantle around the prosthesis should be 2 to 3 mm and that further long-term studies are needed to evaluate the wear properties of titanium-nitride-coated titanium femoral heads.

Cementation↗
PubMed1996

The immunological architecture of B-lymphocyte aggregates in cryptogenic fibrosing alveolitis.

Cryptogenic fibrosing alveolitis (CFA) is believed to have a pathogenesis mediated by the cellular arm of the immune system. Previous studies have, however, indicated the presence of B-lymphocyte aggregates, as well as evidence of local immunoglobulin production and increased levels of B-cell growth factors. It has recently been shown that CFA is associated with the production of circulating IgG autoantibodies to antigen(s) associated with alveolar lining cells. This prompted an examination of the immunological architecture of the B-lymphocyte aggregates, in order to assess whether they might provide histological confirmation of a local humoral immune response in these patients. Thirty-eight consecutive open lung biopsy specimens were examined from patients with CFA and aggregates of B lymphocytes were identified in 37/38. In only five cases were germinal centres seen. The morphological appearances of the aggregates were reminiscent of those observed in mucosal associated lymphoid tissue (MALT). Using immunohistochemistry, despite the low frequency of true germinal centre formation, the B-lymphocyte aggregates were shown to contain the cellular micro-environment necessary for a humoral immune response. In addition, there was evidence of lymphocyte proliferation and activation within these aggregates. These results provide evidence of a local humoral immune response associated with B-lymphocyte aggregates in the lungs of patients with CFA.

Adult↗