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Biomedical subjects

L Read

Publications and source records attributed to L Read.

At least 19 recordsLinked to original sources
PubMed1999

An analysis of hip joint loading during walking, running, and skiing.

PURPOSE: It was the purpose of this study to investigate loading of the hip joint during various skiing activities and to compare the results with walking and running. The results are relevant to determine which skiing activities can be recommended for patients after total hip replacement. METHODS: Nine male subjects were instrumented with a 12-channel accelerometer system mounted on the upper body. Data were collected during walking, running, and six skiing activities and used as input for an inverse dynamic analysis that resulted in the time histories of the intersegmental force and moment at the supporting hip joint. Joint contact force was computed using a simple muscle model. Peak values were determined, averaged over all loading cycles, and compared between activities. RESULTS: Intersegmental force, indicating the influence of upper body weight and accelerations, was highest during running. Intersegmental moments were highest during the alpine skiing activities and indicated large extensor muscle forces at the hip joint. The peak joint contact force during walking at 1.5 m x s(-1) was 2.5+/-0.3 times body weight (BW). Running at 3.5 m x s(-1) produced a joint contact force of 5.2+/-0.4 BW during the push-off phase. Joint contact forces during four different alpine skiing conditions ranged from 4.1+/-0.6 BW (long turns, flat slope) to 7.8+/-1.5 BW (short turns, steep slope). Cross-country skiing had lower hip joint loading than running but higher than walking: 4.0+/-1.1 BW for classical technique and 4.6+/-0.6 BW for skating technique. CONCLUSIONS: Assuming that walking is a "safe" activity for a hip prosthetic patient, controlled alpine skiing and cross-country skiing appear relatively safe with respect to the magnitude of loading. However, the skiing activities showed considerably higher mediolateral and anterior-posterior forces than walking. Mechanical testing of prosthetic devices with loading conditions specific to these activities is needed to assess the effect of these force components on hip prostheses and to allow interpretation with respect to potential effects of skiing for a hip prosthetic patient.

Adult↗
PubMed1997

Physical and transcription map in the region 14q24.3: identification of six novel transcripts.

The region of chromosome 14q24 has been of particular interest as it is known to contain one of the early-onset Alzheimer disease genes (AD3). Other genes of medical interest, such as arrhythmogenic right ventricular cardiomyopathy, have been mapped to this region by linkage analysis or chromosome rearrangements. We have focused on the region of a balanced translocation (2;14)(p25;q24). Members of a family with this translocation all have anterior polar cataracts, suggesting the presence of a gene involved in lens integrity at the vicinity of the breakpoint. The chromosome 14 breakpoint has been defined between the short tandem repeats D14S289 and D14S277, a region of overlap for yeast artificial chromosomes (YACs) 888b2 and 934d4. We have extended the study of the region to 2 Mb on chromosome 14 and present a physical map of this region, including several sequence-tagged sites. New probes were generated using several end clones and inter-Alu PCR fragments from YACs. cDNA selection was used to identify transcribed sequences. Mapping and alignment of 17 nonoverlapping cDNAs completed by sequence and expression pattern analysis suggested that a minimum of eight putative transcription units is present in this region: six of these units correspond to five new genes and one member of a new gene family.

Blotting, Northern↗
PubMed1996

A method for inverse dynamic analysis using accelerometry.

A method was developed to calculate total resultant force and moment on a body segment, in three dimensions, from accelerometer data. The method was applied for an analysis of intersegmental loading at the hip joint during the single support phase of working and running, using four triaxial accelerometers mounted on the upper body. Results were compared to a conventional analysis using simultaneously recorded kinematics and ground reaction forces. The loading patterns obtained by both methods were similar, but the accelerometry method systematically underestimated the intersegmental force and moment at the hip by about 20%. This could be explained by the inertial and gravitational forces originating from the swing leg which were neglected in the analysis. In addition, the accelerometry analysis was not not reliable during the impact phase of running, when the upper body and accelerometers did not behave as a rigid body. For applications where these limitations are acceptable, the accelerometry method has the advantage that it does not require a gait laboratory environment and can be used for field studies with a completely body-mounted recording system. The method does not require differentiation or integration, and therefore provided the possibility of real-time inverse dynamics analysis.

Acceleration↗
PubMed1994

Fidelity of nucleic acid amplification with avian myeloblastosis virus reverse transcriptase and T7 RNA polymerase.

The Nucleic Acid Sequence-Based Amplification (NASBA) process involves alternate steps of DNA synthesis from an RNA template and RNA synthesis from a DNA template, using avian myeloblastosis virus (AMV) reverse transcriptase and T7 RNA polymerase, respectively. The overall fidelity of the amplification process was determined by sequence analysis of cloned DNA products of NASBA reactions. An error frequency of less than 0.3% was observed in cloned DNA products from two different segments of the HIV-1 gag gene. Partial substitution of GTP with ITP in the NASBA reaction did not significantly change the fidelity of the process. An error rate of 2 x 10(-4) was calculated for the combined effects of both polymerases.

Avian Myeloblastosis Virus↗
PubMed1991

Mandibular ramus anatomy as it relates to the medial osteotomy of the sagittal split ramus osteotomy.

The sagittal split ramus osteotomy is probably the most frequently used procedure for correction of mandibular skeletal dentofacial deformities. Despite numerous improvements in the technique in the 30 years since the procedure was introduced, a number of troublesome complications still occur. These include unfavorable fracture during surgery, paresthesia, and relapse. The purpose of this study was to determine where fusion of the buccal and lingual cortical plates occurs in the upper mandibular ramus, as it is thought that placement of the horizontal medial osteotomy above the point of fusion (without any intervening medullary bone) may lead to unfavorable fracture during splitting. Forty-nine human mandibles were sectioned vertically at three locations perpendicular to the surface of the ramus and the occlusal plane. Measurements were made to locate vertically the point of fusion of the buccal and lingual cortical plates relative to the lingula and to the depth of the sigmoid notch. The point of fusion occurred between 7.5 and 13.3 mm above the lingula. Only 2% of mandibles had fusion at or below the level of the lingula in the anterior ramus, whereas in the posterior ramus, 6.1% of mandibles were fused at that level. At a level halfway from the lingula to the sigmoid notch, 20% of mandibles were fused in the anterior ramus, whereas in the mid- to posterior ramus, the incidence was as high as 39%. The location of the medial horizontal osteotomy should be at or just above the tip of the lingula. A higher level of cut may be associated with an increased difficulty in splitting or incidence of unfavorable fracture.

Humans↗
PubMed1991

Mandibular anatomy as it relates to rigid fixation of the sagittal ramus split osteotomy.

Rigid fixation of osteotomy segments is frequently used to reduce relapse and allow for early mobilization of the mandible following the sagittal ramus split osteotomy. This study evaluated cortical bone thickness in the retromolar area of 49 human mandibles to determine if there is an advantage (in terms of cortical thickness) to placement of screws for rigid fixation at the external oblique ridge versus placement at the inferior border. The mandibles were sectioned vertically at three sites in the retromolar area, corresponding to the bone available for rigid fixation of the sagittal osteotomy. Cortical bone thickness was measured at the external oblique ridge and 5 mm above the inferior border. The buccal and lingual cortices were found to be significantly (P less than .001) thicker at the external oblique ridge than at the inferior border. This suggests that there may be an advantage in terms of stability to placement of internal fixation screws at the superior border.

Bone Screws↗
PubMed1990

Biofeedback therapy for female incontinence due to low urethral resistance.

Urinary incontinence, mostly secondary to low urethral resistance, in 15 women was treated for 6 weeks by biofeedback. A new device equipped with visual and audio signals connected to an intravaginal probe was used by the patient for 15 minutes twice a day. Of the patients 12 were continent subjectively and objectively, 2 had 65 and 75% improvement and could lead a normal life, and only 1 failed to respond and was treated surgically. Besides the quality of the device, success depends largely on the quality of moral support given to the patient during the treatment.

Adult↗
PubMed1986

Determining the viability of faecal bacteria present in germ-free mice.

Gram-positive bacilli, originating from the diet, are present in the faeces of germ-free mice in this Unit. Although these organisms have never grown on culture and are assumed to be dead it was considered desirable to test this by non-cultural methods because some gut bacteria are difficult or impossible to grow in vitro by present techniques. Germ-free mice were fed a synthetic diet free from live or dead organisms for 10 days during which time the bacilli disappeared from the faeces, re-appearing when the usual diet was re-introduced. This was regarded as confirmation of the non-viability of the bacilli. The use of Wayson's stain for confirmation of non-viability was found to be inappropriate since it produced false-positive reactions with irradiation-killed bacteria.

Animals↗
PubMed1986

Delay in diagnosing Duchenne muscular dystrophy in orthopaedic clinics.

For clinical, psychological and social reasons the diagnosis of Duchenne muscular dystrophy should be established as early as possible. In a survey of 83 families with 93 affected boys, the diagnosis was missed in every case referred to an orthopaedic surgeon (37 patients). In the whole group there was a mean delay of 2.0 years (0 to 6 years) during which time inappropriate treatment, difficulties in communication with parents, much parental anxiety and further pregnancies occurred. A serum creatine kinase estimation is a simple outpatient test which should be carried out on any boy with clumsy or abnormal gait, with flat feet or with an unexplained equinus deformity.

Child↗
PubMed1985

Smoking relapse situations: a preliminary typology.

This paper presents a preliminary attempt to develop a typology of smoking relapse episodes based on cluster analysis. Descriptions of relapse or near-relapse episodes were collected from 183 ex-smokers. Cluster analysis of 53 cases revealed five clusters in two groups distinguished by a positive (Type I) versus negative (Type II) affective tone. Type Ia situations involve drinking alcohol with others who are smoking. Type Ib situations are associated with relaxation. Type Ic episodes are associated with withdrawal symptoms. Type IIa situations involve anxiety related to work stress. Type IIb episodes occur when the ex-smoker is inactive and bored. Type Ia situations are associated with less behavioral coping and more relapse than the others.

Adaptation, Psychological↗
PubMed1984

The management of equinus deformity in Duchenne muscular dystrophy.

Equinus deformity of the ankle is one of the serious orthopaedic problems associated with Duchenne muscular dystrophy. Sixty-nine patients (age range 4 to 17 years) were treated, 43 conservatively and 26 operatively. They were followed up at six-monthly intervals for a minimum of two years and a maximum of six years. The patients were divided into three groups: independently mobile, mobile in calipers, and wheelchair-bound. It was found that conservative treatment could at best only minimise progression of the deformity. The indications for surgery, the operative procedure and the postoperative management are described; all varied according to the stage of the disease. The postoperative follow-up suggests that, though the deformity recurs, the patients have several years of benefit from the procedure.

Adolescent↗
PubMed1982

Non-union in a fracture of the shaft of the distal phalanx.

Fracture of the shaft of the distal phalanx is less common than more distal fractures involving the tuft: non-union in such a fracture is even more unusual. A case is described in which troublesome non-union of the shaft of the distal phalanx of the middle finger was successfully treated by open reduction and Kirschner wire fixation. The type of fracture and its treatment is discussed: it is emphasised that the principles applied to shaft fractures of the middle and proximal phalanges also apply to the distal phalanx.

Child↗
PubMed1982

Diagnosis and treatment of dyspepsia. A cost-effectiveness analysis.

Dyspepsia is a common problem in ambulatory care. While many authorities recommend ordering upper gastrointestinal x-ray series (UGI) before therapy, there is evidence that clinicians frequently treat dyspepsia without diagnostic procedures. Decision analysis was performed to select optimal management based on probabilities and outcome values from the published literature. The choices evaluated were Symptomatic Therapy (low dose antacids or anticholinergics), Ulcer Therapy (high dose antacids or cimetidine), or UGI followed by further tests or therapy. Our model indicates that mortality is minimized if UGI is performed prior to selection of therapy, and if endoscopy is performed when the x ray shows gastric ulcer. Weeks of pain are minimized if Ulcer Therapy is begun immediately, but direct health care costs are minimized by beginning with Symptomatic Therapy. The marginal cost per additional life saved by performing a UGI rather than beginning with Ulcer Therapy was +1.6 million to +2.3 million, depending on whether endoscopy followed the finding of gastric ulcer. Mortality advantages of the strategies beginning with UGI were sensitive to assumptions regarding the incidence of gastric cancer and the benefits of early diagnosis. With slight reductions in these base case values, the Ulcer Therapy strategy appeared to minimize all outcomes except dollar cost.

Cost-Benefit Analysis↗