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Biomedical subjects

L Del Rio

Publications and source records attributed to L Del Rio.

17 recordsLinked to original sources
PubMed2005

Femur strength index predicts hip fracture independent of bone density and hip axis length.

INTRODUCTION: Proximal femoral bone strength is not only a function of femoral bone mineral density (BMD), but also a function of the spatial distribution of bone mass intrinsic in structural geometric properties such as diameter, area, length, and angle of the femoral neck. Recent advancements in bone density measurement include software that can automatically calculate a variety of femoral structural variables that may be related to hip fracture risk. The purpose of this study was to compare femoral bone density, structure, and strength assessments obtained from dual-energy X-ray absorbtiometry (DXA) measurements in a group of women with and without hip fracture. METHODS: DXA measurements of the proximal femur were obtained from 2,506 women 50 years of age or older, 365 with prior hip fracture and 2,141 controls. In addition to the conventional densitometry measurements, structural variables were determined using the Hip Strength Analysis program, including hip axis length (HAL), cross-sectional moment of inertia (CSMI), and the femur strength index (FSI) calculated as the ratio of estimated compressive yield strength of the femoral neck to the expected compressive stress of a fall on the greater trochanter. RESULTS: Femoral neck BMD was significantly lower and HAL significantly higher in the fracture group compared with controls. Mean CSMI was not significantly different between fracture patients and controls after adjustment for BMD and HAL. FSI, after adjustment for T score and HAL, was significantly lower in the fracture group, consistent with a reduced capacity to withstand a fall without fracturing a hip. CONCLUSION: We conclude that BMD, HAL, and FSI are significant independent predictors of hip fracture.

Absorptiometry, Photon↗
PubMed2004

Timing of follow-up densitometry in hormone replacement therapy users for optimal osteoporosis prevention.

The objectives of the study were (1) to determine the time interval for repeat dual-energy X-ray absorptiometry (DXA) to detect significant bone loss, i.e., greater than the coefficient of variation (CV) of the center (2.8 x CV%) and (2) to assess how long hormone replacement therapy can be maintained to avoid undetected development of low bone mass and to not unduly delay appropriate treatment. A total of 3,826 healthy women, aged 40-65 years, participated in a prospective cohort study, 807 of whom were treated with transdermal estrogen replacement therapy and 626 with transdermal estrogen/progesterone regimens. The untreated group included the remaining 2,393 women. Between 1996 and 2002 they underwent a baseline DXA scan, and DXA scans were then repeated annually. There were no differences among the study groups at entry into the study. Treatment with estrogen was a protective factor for loss of bone mass at the lumbar spine (odds ratio [OR] =0.431, 95% confidence interval [CI] 0.344 to 0.522) and at the femoral neck (OR =0.433, 95% CI 0.352 to 0.521). Treatment with estrogen/progesterone also showed a protective effect against significant changes in follow-up BMD (>2.8 x 1.05% CV of densitometry at L1-L4, >2.8 x 2.3% CV at the femoral neck). In the treated group, significant differences in BMD at the lumbar spine (OR =1.593, 95% CI 1.423 to 2.355) did not appear within the first 3 years, and differences in BMD at the femoral neck (OR =3.555, 95% CI 2.782 to 4.905) did not appear within the first 4 years. It is concluded that in women aged 45-65 years, receiving transdermal hormone replacement therapy without risk factor for loss of bone mass, such as age < 55 years and body mass index <25 kg/m(2), periodical follow-up densitometries would not be necessary, provided that the duration of estrogen or estrogen/progesterone therapy is shorter than 3 years.

Absorptiometry, Photon↗
PubMed2003

Vertebral morphometric X-ray absorptiometry in women with Colles' fracture.

Colles' fracture (CF) in younger postmenopausal women is associated with low bone mineral density (BMD) and with an increased risk of other osteoporotic fractures; however, the prevalence of vertebral deformities has been not studied in CF patients. Vertebral morphometry (MXA) using dual-energy X-ray absorptiometry (DXA) is a research tool developed to evaluate the presence of vertebral deformities, but its clinical use is still limited. The goals of this work were to know the prevalence of vertebral deformities in women with CF, to study the morphometric characteristics of height ratios, and to determine the correlation between MXA findings and BMD. MXA was evaluated within an incident case-control study in which 58 women with a recent CF and 83 population-based control women were enrolled. Anterior (Ha), middle (Hm), and posterior (Hp) heights were measured, and wedge (Ha/Hp) and mid-wedge (Hm/Hp) ratios were calculated. A vertebral deformity was defined when at least one ratio fell 3 SD below the reference mean of that ratio at any vertebral level. The mean age of cases was 65.8 yr and in controls 58.7 (p < 0.05). Morphometric vertebral deformities were found in 19% of cases against 11% of controls (nonsignificant). The cases had a lower mid-wedge ratio than controls at each vertebral level (p < 0.05), while wedge ratio results did not show significant results. When the sample was stratified by age, CF showed a trend to be associated with vertebral deformity only in the younger (<65 yr) group. A low but significant coefficient of correlation was found between mid-wedge ratio and BMD, mainly at hip level. By using MXA we found that younger Colles' fracture cases were likely to have more vertebral deformities than healthy controls of the same age range.

Absorptiometry, Photon↗
PubMed2002

Association between Colles' fracture and low bone mass: age-based differences in postmenopausal women.

Colles' fracture (CF) in postmenopausal women has been linked to low bone mass at the lumbar spine and hip. However, the diverse methodological approaches of previous studies make the results difficult to compare and thus the implications of CF in osteoporosis daily clinical practice are not clear. We explored the association between CF and low bone mineral density (BMD) in an incident case-control study in 58 postmenopausal Spanish women aged 45-80 years with recent CF and in 83 population-based controls of the same age range. The BMD of ultradistal distal forearm, lumbar spine and hip was measured by dual-energy X-ray absorptiometry (DXA) and WHO criteria were used to define osteoporosis and osteopenia. BMD was significantly lower in cases for all three areas ( p<0.001). Osteoporosis was more prevalent in cases than controls in the wrist (60% vs. 35%, p<0.001), lumbar spine (47% vs. 20%, p<0.005) and hip (19% vs. 6%, p<0.005). After adjusting for age, menopausal status and body mass index, osteoporosis and osteopenia remained significantly associated with CF only in women aged 65 years or less (ultradistal forearm OR 5.7 (95% CI 1.2-27.2), lumbar spine OR 3.9 (95% CI 1.1-14.3)). We conclude that CF in postmenopausal women aged 65 or less may be used as a sentinel finding to identify patients with generalized osteoporosis. Additionally, 70% of all CF patients regardless of their age had low bone mass ( T-score<-1SD) in any studied site.

Absorptiometry, Photon↗
PubMed2001

CXCR2 deficiency confers impaired neutrophil recruitment and increased susceptibility during Toxoplasma gondii infection.

Neutrophil migration to the site of infection is a critical early step in host immunity to microbial pathogens, in which chemokines and their receptors play an important role. In this work, mice deficient in expression of the chemokine receptor CXCR2 were infected with Toxoplasma gondii and the outcome was monitored. Gene-deleted animals displayed completely defective neutrophil recruitment, which was apparent at 4 h and sustained for at least 36 h. Kit(W)/Kit(W-v) animals also displayed defective polymorphonuclear leukocyte migration, suggesting mast cells as one source of chemokines driving the response. Tachyzoite infection and replication were accelerated in CXCR2(-/-) animals, resulting in establishment of higher cyst numbers in the brain relative to wild-type controls. Furthermore, serum and spleen cell IFN-gamma levels in infected, gene-deleted mice were reduced 60-75% relative to infected normal animals, and spleen cell TNF-alpha was likewise reduced by approximately 50%. These results highlight an important role for CXCR2 in neutrophil migration, which may be important for early control of infection and induction of immunity during Toxoplasma infection.

Animals↗
PubMed2001

Field evaluation of a new commercially available ELISA based on a recombinant antigen for diagnosing Chlamydophila abortus (Chlamydia psittaci serotype 1) infection.

A new commercially available ELISA (ELISAr-Chlamydia) for detecting antibodies against Chlamydophila abortus has been evaluated using sheep field serum samples. The ELISA is based on a recombinant antigen which expresses part of a protein from the 80-90kDa family that is specific to C. abortus. Sera (105) from six flocks with confirmed ovine chlamydial abortion (OEA) outbreaks were used in this study, as well as sera (258) from 18 flocks which had suffered no OEA in the last lambing. The ELISAr-Chlamydia was compared with the complement fixation test (CFT) and with an ELISA using purified C. abortus elementary bodies (ELISA-EB), employing as reference technique a comparative microimmunofluorescence test that differentiates C. abortus infection from Chlamydophila pecorum infection. The results showed that the sensitivity of ELISAr-Chlamydia was 90.9% with a specificity of 85.9%, the sensitivity of CFT was 71.0% with a specificity of 83.6%, while the sensitivity of ELISA-EB was 95.2% and the specificity was 54.2%. Furthermore, ELISAr-Chlamydia was the test with fewer false positives resulting from positive reactivity to C. pecorum, although 15% of the sera positive for C. pecorum but negative for C. abortus antibodies reacted positively. This study demonstrated with field material that ELISAr-Chlamydia provides the most balanced results between sensitivity and specificity, especially in flocks with no clinical OEA but reactivity to C. abortus.

Abortion, Veterinary↗
PubMed2001

Differences in lymphocyte subpopulations from peripheral blood and lymphoid organs in natural caprine tuberculosis infection.

Although the cell-mediated immune response is known to be a critical factor in host defence against intracellular mycobacterial infection, the different components of the T-cell response are unclear, particularly in caprine infection. In this study we examine the differences in the lymphocyte population of peripheral blood, spleen and mediastinal and superficial lymph nodes in 11 naturally infected goats showing positive reactions in the comparative tuberculine intradermal test. According to the different types of lesion showing, the goats were classified into proliferative or exudative tuberculosis. The results obtained by fflow cytometry analysis indicated that the main differences in peripheral blood were in the CD4 T-cell population, which decreased markedly in goats with exudative tuberculosis, while the CD8 and B cells increased in number. The gamma/delta T cells did not show significant differences in either type of tuberculosis, while interleukin-2 receptor cells decreased slightly in the exudative tuberculosis. The CD4:CD8 ratio was higher than 1 in goats with proliferative tuberculosis and lower than 1 in goats with exudative tuberculosis. In general, the lymphoid organs of the goats with exudative tuberculosis showed a significant increase in the number of CD8 T cells (CD4:CD8 ratio of less than 1) whereas no significant differences were observed in the CD4 T population between either type of tuberculosis.

Animals↗
PubMed1995

Anteroposterior versus lateral bone mineral density of spine assessed by dual X-ray absorptiometry.

Recently, it has been suggested that lateral (LAT) spine bone mass measurements by absorptiometry may be more sensitive for detecting bone loss than the standard anteroposterior (AP) projection. The aim of this study was to evaluate the precision of LAT spine dual-energy X-ray absorptiometry (DEXA) and its diagnostic sensitivity. A group of 1554 subjects with no risk factors that might affect bone metabolism and 185 osteoporotic patients with vertebral fractures were studied. Bone mineral density (BMD) was measured in the lumbar spine (standard AP and LAT projections) and proximal femur with a DEXA absorptiometer. The precision of the measurements was assessed in 15 volunteers. Diagnostic sensitivity was evaluated by the Z-score method. Comparing young people and the elderly, spine bone loss in the latter was similar for AP and LAT projections, when it was evaluated in absolute values (glcm2). However, when it was evaluated in percentage terms, bone loss was about twice as high in the LAT projection. LAT spine BMD correlated significantly with all the other areas assessed. The best correlation was found with the standard AP projection (r = 0.67, P < 0.0001). The precision in the LAT projection was found to be within an acceptable range (1.6% in normal subjects, 2% in osteoporotic patients), even though it was about twice that obtained in the AP projection. Diagnostic sensitivity was also better with the AP projection. It is concluded that LAT spine BMD measurements can be assessed with acceptable precision although it is about twice as high as for AP spine measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1995

Bone remodelling in human immunodeficiency virus-1-infected patients. A histomorphometric study.

The aim of this study was to identify and describe possible alterations of bone histomorphometry in patients with human immunodeficiency virus (HIV-1) infection and to assess the relation between these alterations and disease severity. Forty-four HIV-1-infected patients seen successively at our hospital were evaluated for the study. In an attempt to avoid confounding factors as far as possible, we excluded patients who fulfilled any of the following criteria: age less than 18 or greater than 40 years; recent history of extended bed rest; previous diagnosis of metabolic bone disease, renal insufficiency, or hepatic failure; clinical or echographic signs of liver cirrhosis; diabetes mellitus or previous diagnosis of other endocrine diseases; drug therapy that could act on bone metabolism; and/or moderate to severe nutritional alteration. Twenty-two patients (13 men, 9 women; age: 27.9 +/- 4.1 years, mean +/- standard deviation) were included in the study. Plasma and urine biochemistry and calcium-regulating hormones were determined. Bone mineral content was measured on vertebrae L2 to L4 and on the neck and intertrochanteric areas of the femur by dual-photon absorptiometry. A transiliac bone biopsy was performed after double-tetracycline labelling, with histomorphometric study of undecalcified bone. Serum osteocalcin was found to be lower in patients who, according to the Centers for Disease Control (CDC) classification, had greater disease severity, and showed a positive correlation with the number of CD4+ T lymphocytes. No alterations in bone densitometry were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1991

Vertebral fractures in steroid dependent asthma and involutional osteoporosis: a comparative study.

BACKGROUND: Reduced bone mass predisposes patients to the development of vertebral fractures. Measurement of bone mass by non-invasive methods is used to detect patients with involutional osteoporosis at risk from fractures. These methods have not been assessed in patients with steroid dependent osteoporosis. The objective of this study was to assess the value of a predictive fracture threshold value of bone density in patients with steroid dependent asthma. METHODS: Three groups of patients were studied. Group 1 (67 patients) had steroid dependent asthma (mean daily dose of prednisone 11.7 mg) and no vertebral fractures, group 2 (32 patients) had steroid dependent asthma (mean daily dose of prednisone 12 mg) and vertebral fractures, and group 3 (55 patients) were not taking steroids but had involutional osteoporosis and a recent non-traumatic vertebral fracture. Bone mineral density was measured by dual photon absorptiometry and vertebral fractures by radiography of the lumbar spine. A fracture threshold was determined in the two groups with fractures as the 90th percentile of the mean bone mineral density measured in the lumbar spine. RESULTS: Bone mineral density was significantly higher in the steroid dependent group with fractures (group 2) than in group 3 patients, who had involutional osteoporosis and fractures (0.946 (0.18) g/cm2 v 0.830 (0.16) g/cm2). The fracture threshold value was therefore higher for patients with steroid related vertebral fractures (group 2, 1.173 g/cm2) than for those with involutional osteoporosis (group 3, 0.979 g/cm2). Vertebral fractures were more likely to occur in steroid dependent asthmatic patients with bone density above the fracture threshold value (obtained from subjects with involutional osteoporosis) than in subjects in group 3 (34% v 9%). CONCLUSION: Vertebral fractures occur in patients treated with steroids in the presence of higher bone mineral density than is the case with patients with involutional osteoporosis. The findings suggests that the assessment of the efficacy of preventive treatment requires measurement of bone mineral density and radiology.

Adult↗
PubMed1990

Treatment of steroid-induced osteopenia with calcitonin in corticosteroid-dependent asthma. A one-year follow-up study.

Sixty-two steroid-dependent asthmatics who had not received any form of treatment to prevent bone loss were studied during a 12-month period. Patients were randomly divided into two groups. Thirty-one patients were treated with 1 g of elemental calcium taken daily plus 100 IU of salmon calcitonin every other day, administered subcutaneously; the remaining 31 patients received only calcium supplementation. In the calcitonin group, 11 patients dropped out of the study because of severe side effects (seven patients), lack of compliance (three patients), and exacerbation of asthma (one patient). The 20 patients who completed the 12-month follow-up period were analyzed and compared with 20 sex-matched patients from the control group. At one year, bone mineral density (BMD) had increased in the calcitonin group by a mean of 4% (p less than or equal to 0.001), whereas in the control group BMD had decreased by 2.5% (p less than or equal to 0.05). Parameters of bone remodeling (alkaline phosphatase and osteocalcin) decreased significantly in the calcitonin-treated group but not in the control group. Our findings show that calcitonin 100 IU, given three times/wk, is an effective drug in the treatment of steroid-induced osteopenia. Side effects, however, are frequent and cause a high degree of dropout from therapy. These findings suggest that further studies should be carried out with lower doses of calcitonin or by other better tolerated forms of delivery such as in a nasal spray.

Asthma↗
PubMedDate not supplied

Differences in the immune response against ruminant chlamydial strains in a murine model.

CBA/J mice were used in the present study to establish differences between the immune response to three chlamydial strains: AB7 (Chlamydia psittaci wild-type strain), 1B (C. psittaci vaccinal strain) and iB1 (C. pecorum). The evolution of chlamydial infection was evaluated in each strain by studying the clinical signs, the number of bacteria isolated from the spleen and the pathology of the liver. Three aspects of the immune response were then studied: the characterization of the infiltrate of leukocytes in the liver, the percentages of T- and B-cells, macrophages and neutrophils in the spleen, and the presence of cytokines in the serum. Infection followed a different course in the C. psittaci-infected mice; 1B-infected mice showed milder levels in all the parameters analysed than their AB7-infected counterparts. The resolution of infection was earlier in 1B-infected mice and, although the immune response to both strains was Th1-like, a more intense CD8+ T-cell response and an earlier presence of TNF-alpha in serum were observed in this group. C. pecorum infection was controlled mainly by a non-specific immune response, since these mice showed no signs of a systemic specific immune response. Neutrophil depletion experiments showed that these cells play a very limited role in the non-specific response against C. pecorum.

Animals↗