Biomedical subjects

L C Jones

Publications and source records attributed to L C Jones.

At least 37 records · Page 2Linked to original sources

PubMed2000

Reinfusion drains after primary total hip and total knee arthroplasty.

The purposes of this study were to evaluate the efficacy of intraoperative surgeon-elected reinfusion drain placement and to determine whether drainage at 90 minutes is useful in predicting the need for a reinfusion drain. In the standard drain hip arthroplasty group, 6 of 30 patients (20%) received a reinfusion, similar to the 11 of 41 patients (27%) in the reinfusion drain group. In the total knee arthroplasty group, 38 of 45 patients (84%) in the standard group had reinfusion, similar to the 23 of 27 patients (85%) in the reinfusion drain group. The surgeon could not predict intraoperatively which patients would need a subsequent reinfusion drain. However, in more than 94% of the cases, one could know by 90 minutes postoperatively whether a reinfusion would be necessary. We believe that a drain that can be converted to a reinfusion drain in the recovery room would be the most cost-effective drain system.

Adult↗

PubMed1999

Modeling late effects in hypofractionated stereotactic radiotherapy.

PURPOSE: To investigate the effect of increasing fraction size on cell survival in late responding normal tissues. The hypothesis is that total dose can be reduced for constant tumor cell kill and there will be consequent advantage for some surrounding normal tissue cells. Also, the volume of normal tissue that can potentially be damaged by increasing fraction size is minimized by a high degree of dose conformation achievable in stereotactic radiotherapy (SRT). METHODS AND MATERIALS: The linear quadratic (LQ) model has been used to calculate the allowed reduction in total dose with increased fraction size, using tumor alpha/beta ratios of 5 Gy and 10 Gy. Effect on normal tissue is calculated using an alpha/beta ratio of 3 Gy. Maximum dose is normalized to 100% and the effect on normal tissue at different isodose levels assessed. A new quantity, the standard percentage dose, is proposed in order to describe a dose distribution in terms of an isodose distribution for a standard fraction size. Integral biologically effective dose (IBED) in the brainstem is calculated, where the variation with isocenter position and fraction size is considered. RESULTS: The decreasing total dose resulting from increasing the dose per fraction is found to reduce late normal tissue effect for low isodose levels. The threshold isodose level at which there is an advantage corresponds to the ratio of normal tissue to tumor alpha/beta ratios. Brainstem IBED for a higher dose per fraction increases relative to that for a low dose per fraction, when a larger volume of brainstem is covered by high isodose levels. CONCLUSION: Hypofractionation may be biologically sound when a small volume of normal tissue is covered by high isodose levels. There is a calculated advantage in using larger fractions in terms of cell survival at low isodose levels.

Brain Neoplasms↗

PubMed1999

Immunohistochemical evaluation of interface membranes from failed cemented and uncemented acetabular components.

Aseptic loosening of acetabular components is a primary factor compromising the long-term outcome of cemented and cementless total hip replacement. It is unknown whether the pathogenesis of the loosening process is identical for both types of fixation. The specific aim of this study was to determine whether there is a difference in the cellular and cytokine profiles of interface membranes removed from between the implant and the host bone from failed cemented (n = 5) and failed cementless acetabulae (n = 5). Routine histology and immunohistochemical evaluations were completed on each tissue specimen. The monoclonal antibodies used included those specific for cell types (macrophages, fibroblasts, T lymphocytes) and for cytokines (IL-1beta, IL-6, TNF-alpha). The patients were all revised for loosening. The time to revision was significantly longer for the cemented group (16.6 yr; 13-21 range) than for the cementless group (8.9 yr; 4-13 range). In all cases, slides from each group stained positively for each of the cell types and cytokines evaluated. Immunohistochemical analyses indicated a predominance of macrophages and ubiquitous staining for the cytokines IL-1beta and TNF-alpha within the membranes of both patient groups. The intensities of cytokine staining were similar for both patient groups. More regions of fibroblastic connective tissue were observed surrounding failed cementless components as compared to those of the cemented group. The clinical ramification of our findings is that, despite differences in the cellular composition of the periprosthetic membranes, the membranes from failed cemented and cementless implants contain cytokines, which have been shown to be capable of modulating the inflammatory response. These inflammatory mediators are likely to play a significant role in the development of osteolysis and prosthetic loosening.

Acetabulum↗

PubMed1999

Variation of rotation moment arms with hip flexion.

Excessive flexion and internal rotation of the hip is a common gait abnormality among individuals with cerebral palsy. The purpose of this study was to examine the influence of hip flexion on the rotational moment arms of the hip muscles. We hypothesized that flexion of the hip would increase internal rotation moment arms and decrease external rotation moment arms of the primary hip rotators. To test this hypothesis we measured rotational moment arms of the gluteus maximus (six compartments), gluteus medius (four compartments), gluteus minimus (three compartments) iliopsoas, piriformis, quadratus femoris, obturator internus, and obturator externus. Moment arms were measured at hip flexion angles of 0, 20, 45, 60, and 90 degrees in four cadavers. A three-dimensional computer model of the hip muscles was developed and compared to the experimental measurements. The experimental results and the computer model showed that the internal rotation moment arms of some muscles increase with flexion; the external rotation moment arms of other muscles decrease, and some muscles switch from external rotation to internal rotation as the hip is flexed. This trend toward internal rotation with hip flexion was apparent in 15 of the 18 muscle compartments we examined, suggesting that excessive hip flexion may exacerbate internal rotation of the hip. The gluteus maximus was found to have a large capacity for external rotation. Enhancing the activation of the gluteus maximus, a muscle that is frequently underactive in persons with cerebral palsy, may help correct excessive flexion and internal rotation of the hip.

Biomechanical Phenomena↗

PubMed1999

Standard effective doses for proliferative tumours.

This study was undertaken to investigate the treatment schedules used clinically for highly proliferative tumours, particularly with reference to the effects of fraction size, fraction number and treatment duration. The linear quadratic model (with time component) is used here to compare non-standard treatment regimens (e.g. accelerated and hyperfractionated schedules), currently the focus of randomized trials, with each other and some common 'standard regimens'. To ensure easy interpretation of results, two parameters known as proliferative standard effective dose one (PSED1) and proliferative standard effective dose two (PSED2) have been calculated for each regimen. Graphs of PSED1 and PSED2 versus potential doubling time (Tp) have been generated for a range of fractionation regimens which are currently under trial in various randomized studies. From these graphs it can be seen that the highly accelerated schedules (such as CHART) only show advantages for tumours with very short potential doubling times. Calculations for most of the schedules considered showed at least equivalent tumour control expected for the trial schedule compared with the control arm used and these values agree quite well with clinical results. These calculations are in good agreement with clinical results available at present. The greater the PSED1 or PSED2 for the schedule considered the greater the tumour control, which can be expected. However, as has been seen with clinical trials, this higher cell kill also results in higher acute effects which have proved too great for some accelerated schedules to continue.

Cell Division↗

PubMed1999

Pathologic features in steroid and nonsteroid associated osteonecrosis.

Multiple pathophysiologies for osteonecrosis have been postulated and various associated risk factors defined for this disease. However, the pathologic findings of the end stage disease are thought to be similar in all patients. To the author's knowledge, there are no data in the literature comparing the pathologic characteristics of osteonecrosis in a quantitative manner between groups of patients with different associated risk factors. The current study examined the pathologic features of core decompression specimens from the femoral head in a group of patients with osteonecrosis associated with corticosteroid therapy and compared them with specimens from patients with osteonecrosis with no history of corticosteroid therapy. The study group comprised 65 patients (96 hips); 45 patients (68 hips) in the corticosteroid group and 20 patients (28 hips) in the noncorticosteroid group. In the corticosteroid group, 65% of dead bone was identified histologically (44 of 68) as compared with 46% (13 of 28) in the noncorticosteroid group. Specimens staged according to the histologic grading system of Arlet and Durroux revealed the corticosteroid group had a higher incidence of late stage lesions than did the noncorticosteroid group. This was found even though the two groups had similar radiographic staging distribution. The hips in patients who used alcohol were comparable pathologically to the hips in patients who used corticosteroids. This study emphasizes that the histologic features of necrosis and repair are similar in corticosteroid and noncorticosteroid osteonecrosis. However, there were differences in the distribution of viable bone and pathologic stage of the lesions in the two groups, suggesting a more rapid evolution of changes in the corticosteroid group.

Adult↗

PubMed1998

Linkage of familial Hibernian fever to chromosome 12p13.

Autosomal dominant periodic fevers are characterized by intermittent febrile attacks of unknown etiology and by recurrent abdominal pains. The biochemical and molecular bases of all autosomal dominant periodic fevers are unknown, and only familial Hibernian fever (FHF) has been described as a distinct clinical entity. FHF has been reported in three families-the original Irish-Scottish family and two Irish families with similar clinical features. We have undertaken a genomewide search in these families and report significant multipoint LOD scores between the disease and markers on chromosome 12p13. Cumulative multipoint linkage analyses indicate that an FHF gene is likely to be located in an 8-cM interval between D12S77 and D12S356, with a maximum LOD score (Z max) of 3.79. The two-point Z max was 3.11, for D12S77. There was no evidence of genetic heterogeneity in these three families; it is proposed that these markers should be tested in other families, of different background, that have autosomal dominant periodic fever, as a prelude to identification of the FHF-susceptibility gene.

Chromosome Mapping↗

PubMed1998

Radiographic predictors of outcome of core decompression for hips with osteonecrosis stage III.

Various investigators have studied the prognostic influence of various demographic, laboratory, and radiographic parameters on outcome for different treatment methods for osteonecrosis of the femoral head. A cross sectional study was done of 52 patients (68 hips) who had a core decompression for Ficat and Arlet Stage III osteonecrosis of the femoral head. The purpose of this study was to evaluate the prognostic significance of various radiographic factors for risk of disease progression after treatment with core decompression. Radiographic parameters included Steinberg stages (III or IV), Ohzono stage (central or lateral location), amount of head depression, extent of crescent sign arc, and extent of lesion by Kerboul combined necrotic angle measurements. Patient outcome assessment was at a followup mean of 12 years (range, 4-18 years) after core decompression. Overall, 20 of the 68 hips (29%) had satisfactory outcomes. Of the 44 hips with Steinberg Stage III disease, 18 (41%) underwent total hip arthroplasty. In comparison, in the Steinberg Stage IV hips, 22 of 24 hips (92%) underwent arthroplasty. Ohzono Stage B lesions had 50% survival (eight of 16 hips) compared with 23% survival (12 of 52 hips) for Ohzono Stage C. Hips with combined necrotic angles greater than 250 degrees had 16% survival (seven of 45) which can be compared with 57% survival (13 of 23) for hips with angles less than 250 degrees. The best multiple regression model for a satisfactory outcome was a Steinberg Stage III hip (no head depression), a central lesion (Ohzono Stage B), and a small lesion (< 250 degrees combined necrotic angle). With this combination, there were 89% satisfactory outcomes (8 of 9 hips). Conversely, the best generalized linear model for unsatisfactory outcomes (0 hips surviving of 14) was Steinberg Stage IV disease (head depression), lateral location (Ohzono Stage C lesion), and a large extent of the lesion (> 250 degrees combined necrotic angle).

Adult↗

PubMed1998

Osteonecrosis of the humeral head treated by core decompression.

Core decompression is one treatment used for symptomatic osteonecrosis of the humeral head. The purpose of this report was to examine the long term outcome of this procedure. Sixty-three shoulders in 43 patients who underwent a core decompression for humeral head osteonecrosis were followed up from 2 to 20 years (mean, 10 years). None of these patients had responded to nonoperative treatment before core decompression. Results of core decompression according to preoperative Ficat and Arlet stage revealed Stage I disease had 15 of 16 (94%) successful outcomes and Stage II had 15 of 17 (88%) successful outcomes. Stage III had 16 of 23 (70%) successful results and Stage IV had one of seven (14%) successful result. Core decompression of the shoulder is a safe procedure with few recognized complications and can be performed on an outpatient basis. The procedure has been successful for Stages I, II, and III osteonecrosis in terms of early relief of pain and increased function.

Activities of Daily Living↗

PubMed1998

Exclusion of the familial Mediterranean fever locus as a susceptibility region for autosomal dominant familial Hibernian fever.

Autosomal dominant periodic fevers constitute a range of syndromes characterised by recurrent attacks of fever and abdominal pain. Familial Hibernian fever (FHF) has been described in only one United Kingdom based family, but two other Irish families have been found with similar clinical features. FHF resembles familial Mediterranean fever (FMF) in several clinical features, but the mode of inheritance of FHF is dominant whereas FMF is recessive. We have investigated whether autosomal dominant periodic fevers, in particular FHF, map to the FMF susceptibility locus (MEFV) on chromosome 16p13.3. We have used informative microsatellite markers flanking this locus to genotype members of the three families mentioned above. Two point and multipoint lod scores definitively excluded linkage to MEFV in the two larger families. A haplotype study confirmed these findings, indicating that FHF is genotypically as well as phenotypically distinct from FMF.

Chromosomes, Human, Pair 16↗

PubMed1998

The cAMP-response element mediates induction of secretogranin II by CHX and FSK in GH4C1 cells.

The effect of cAMP on secretogranin II (SgII) gene transcription in GH4C1 (GH) cells is not observed unless protein synthesis is inhibited. We have defined elements in the SgII promoter that mediate regulation by cycloheximide (CHX) and forskolin (FSK) and characterized the nuclear proteins that interact with them. GH cells were transfected with p2774Luc, p351Luc, p242Luc, and p223Luc containing 2,612, 189, 80, and 61 bp of the SgII promoter upstream of the luciferase gene, respectively. Treatment with CHX and FSK increased promoter activity 8- to 12-fold in cells transfected with p2774Luc, p351Luc, and p242Luc but had not effect in cells transfected with p223Luc. The same 19-bp element (-80 to -62) mediates regulation by CHX alone, as CHX caused a 3.8-fold increase in activity in GH cells transfected with p242Luc but not p223Luc. Gel mobility shifts using sequences -84 to -53 resulted in three complexes, which contained cAMP response element-binding protein heterodimerized with cAMP response element modulator or activating transcription factor-1. No differences were observed in complex formation when cells were treated with either CHX, FSK, or CHX and FSK. Thus CHX affects the response to FSK in GH cells by inhibiting the synthesis of a protein, which does not itself interact with DNA or affect the binding of CRE-binding proteins with the SgII promoter, but likely interferes with the interaction of CRE-binding proteins with the general transcriptional machinery.

Animals↗

PubMed1998

Multifocal osteonecrosis.

OBJECTIVE: To study demographic, clinical, and radiographic staging patterns in patients with multifocal osteonecrosis to facilitate earlier diagnosis and optimize treatment. METHODS: Multifocal osteonecrosis was defined as disease of 3 or more anatomic sites. Patients were characterized demographically, which included disease associations, corticosteroid and other agent usage, presenting joints, and symptomatology. Radiographically, patients were evaluated with plain radiographs and magnetic resonance imaging (MRI) scans of all joints to determine the presenting stage of the lesions. RESULTS: We found that 32 of 1056 (3%) osteonecrosis patients under our care had multifocal disease. Associated factors included systemic lupus erythematosus (13 patients), inflammatory bowel disease (5 patients), malignancy (4 patients), and renal transplantation (3 patients). Thirty of the 32 patients (94%) had a history of corticosteroid therapy, with the other 2 patients found to have a coagulopathy. All 32 patients had bilateral femoral head involvement and 30 of 32 had bilateral knee involvement, with the other 2 having only left knee lesions. Osteonecrosis was also seen in the shoulder (28 patients), ankle (8 patients), and 3 other sites. Overall, 201 sites were involved (6.3 per patient). The majority of joints presented in a pre-collapse stage (77%). Patients most commonly presented with hip or multiple joint symptoms (22 patients, 69%). In 8 patients, the knee was the sole presenting symptomatic joint and the ankle and shoulder were the sole presenting symptomatic joints in one patient each. CONCLUSION: In patients with a diagnosis of osteonecrosis and complaints in other joints, these other areas should be fully evaluated with plain radiographs and, if inconclusive, with MRI. In patients with osteonecrosis not involving the femoral head, the patient's hips should be radiographically evaluated regardless of whether the patient is symptomatic. Patients diagnosed with osteonecrosis of the knee, shoulder, or ankle should have other joints evaluated, as such patients have multifocal disease roughly 50% of the time.

Adrenal Cortex Hormones↗

PubMed1998

Osteonecrosis of the femoral head. Potential treatment with growth and differentiation factors.

Basic and clinical research have shown the efficacy of various cellular mediators (bone morphogenetic proteins, interleukins, angiogenic growth factors) in healing bone defects. The potential application of these growth and differentiation factors to other musculoskeletal conditions, including osteonecrosis of the femoral head, only recently has been explored. Osteonecrosis is a disease of unknown pathogenesis that usually progresses to hip joint destruction necessitating total hip arthroplasty. The pathology involves ischemic events followed by death of bone and marrow elements. A process of repair then is initiated, but unless the lesion is small (less than 15% of the femoral head involved), this repair process is usually ineffective. The net result is weakening of subchondral bone with subsequent collapse of the articular surface. Because the results of hip arthroplasty in patients with osteonecrosis are relatively poor, much focus has been on modalities aimed at femoral head preservation. The surgical alternatives may include core decompression, osteotomy, nonvascularized, and vascularized bone grafting, which might be enhanced with the use of growth and differentiation factors. At least three of these factors are potential candidates as therapeutic modalities: cytokines (such as interleukins, tumor necrosis factors, and signaling molecules such as fibroblast growth factors, platelet derived growth factors, insulinlike growth factors, and transforming growth factor betas), bone morphogenetic proteins, and angiogenic factors. Despite considerable effort, evaluation of these growth and differentiation factors has been hampered by the lack of an animal model that adequately simulates the pathology of osteonecrosis in humans. Therefore, investigators have attempted to model certain aspects of the disease process. Recently, several investigators have attempted to mimic osteonecrosis in the femoral head of large mammals by combinations of devascularization, freezing, osteotomy of the femoral neck, or creation of a head defect. Results from some of these studies have confirmed the potential for growth and differentiation factors to effect more rapid healing and filling of defects with biomechanically competent and viable bone. The application of this therapy shows promise, and clinical studies on efficacy and safety are ongoing.

Angiogenesis Inducing Agents↗

PubMed1997

Self-esteem, optimism, and postpartum depression.

This study was conducted to assess the predictive utility of self-esteem and dispositional optimism to postpartum depression. Forty-five British women completed standard measures of self-esteem, optimism, and postpartum depression several weeks before childbirth. Depression was again measured at two and six weeks postpartum. Optimism was associated with less depressive symptoms during pregnancy and at two weeks postpartum, while self-esteem was associated with lower depression over all three administrations. After controlling for optimism and earlier levels of depressive symptoms, self-esteem remained associated with lower levels of depressive symptoms two weeks postpartum. This suggests that self-esteem and not optimism appears to be a reliable contributing factor to the differential susceptibility to depression in the early postpartum period.

Adult↗

PubMed1997

Effects of grafting on porous metal ingrowth. A canine model.

Twenty-five mongrel dogs were studied using implantation of autograft, fresh-frozen allograft, and beta-tricalcium phosphate around a porous-coated chrome-cobalt plug in the distal femoral metaphysis; interference-fit and overreamed control specimens were also studied. Over the course of this 4-month study, bone ingrowth through the grouting materials into the center plug was noted for autologous, allograft, and ceramic specimens. Quantitatively, in terms of push-out strength and histology, there were no significant differences between grafted groups; significantly higher push-out strengths were attained in each grafted subgroup compared with nongrafted, overreamed control subjects. In the setting of uncemented revision total hip arthroplasty, bone-grafting is frequently required. Because of the limited availability of autogenous bone and the potential liabilities of allograft material, attention has been given to bone substitutes. On the basis of this preliminary study, bone ingrowth into a porous metal substrate has been documented to occur through autograft, allograft, or ceramic grouting agents. Within the limits of this nonloaded experimental model, it appears that these materials are comparable in terms of their osteoconductive capability. Even in the optimal laboratory situation, bone ingrowth does not appear to occur in a canine model across a nongrafted 2-mm gap with regularity over a 16-week period.

Animals↗

PubMed1997

Use of fenbendazole for long-term control of protostrongylid lungworms in free-ranging Rocky Mountain bighorn sheep.

In an effort to control Protostrongylus spp. in a Rocky Mountain bighorn sheep herd (Ovis canadensis canadensis) of approximately 30 animals, fenbendazole-medicated salt was placed on the Stillwater bighorn winter range in southcentral Montana (USA) for four consecutive winters, 1990 to 1993. Sheep of all age and sex classes were observed using the medicated salt throughout the study period. Prevalence and average number of lungworm larvae per gram of bighorn feces declined significantly (P < 0.05) from pretreatment levels (1987 to 1989), and remained low throughout the study period. Free-choice availability of fenbendazole-medicated salt is a potentially effective management tool for long-term control of protostrongylid lungworm.

Administration, Oral↗

PubMed1997

Social categorization and the formation of intergroup attitudes in children.

The study was designed to test several hypotheses derived from intergroup theory concerning the effects of the presence of a novel social category on the formation of intergroup attitudes. Elementary school children (N = 61; aged 6-9) were given measures of classification skill and self-esteem and assigned to 1 of 3 types of school classrooms in which teachers made: (1) functional use of "blue" and "yellow" groups assigned on the basis of a biological attribute, (2) functional use of "blue" and "yellow" groups assigned on the basis of a random drawing, or (3) no explicit groups (despite the presence of blue and yellow groups). After 4 weeks, children completed measures of intergroup attitudes and behavior. As predicted, the functional use of color groups affected children's attitudes toward group members, with children showing consistent biases favoring their own group. Children with higher levels of self-esteem showed higher levels of intergroup stereotyping.

Child↗

PubMed1996

Bioelectrical impedance for monitoring the efficacy of lymphoedema treatment programmes.

The treatment of lymphoedema includes a combination of massage, compression bandaging, and exercise. To date the most common technique of assessing the efficacy of treatment has involved estimating the total limb volume from circumferential measurements at fixed intervals along the limb. This study investigated the application of multiple frequency bioelectrical impedance analysis, MFBIA, to monitor the volume of lymphoedema in the upper limb of patients who developed this disorder following surgery for cancer of the breast. Daily measurements of both circumference and impedance of both the affected and unaffected limbs were recorded for 20 patients throughout their 4 week treatment programmes. Twenty control subjects were also monitored daily over a similar 4 week period. Prior to the commencement of treatment the bioimpedance technique detected a significant (P < 0.01) asymmetry between the two limbs of the control subjects, associated with handedness (P < 0.001). Circumferential estimates of limb volumes in the control group detected no asymmetry. Impedance measures of extracellular fluid showed all of the patients to lie outside the 95% confidence interval determined from the data of the control group. The trends of the impedance measures and the circumferential estimates of volume throughout the 4 week program were found to be significantly different (P < 0.05); MFBIA exhibiting a greater sensitivity in the detection of lymphoedema. The results demonstrate that MFBIA is significantly more sensitive than circumferential measurement both in the early diagnosis of lymphoedema and in monitoring change.

Adult↗