Biomedical subjects

A Sanchez-Atrio

Publications and source records attributed to A Sanchez-Atrio.

8 recordsLinked to original sources

PubMed2001

Cell surface CD28 levels define four CD4+ T cell subsets: abnormal expression in rheumatoid arthritis.

CD28 is a costimulatory receptor expressed in most CD4(+) T cells. Despite the long-standing evidence for up- and downregulation of surface CD28 expression in vitro, and the key regulatory role assigned to the upregulation of CD28 counterreceptor [the CD152 (CTLA-4) molecule], in vivo CD28 induction has attracted little attention. We studied CD28 and CD152 expression and function in 33 rheumatoid arthritis (RA) patients, 20 clinically active and 13 inactive, and in 24 healthy donors. Four subsets of CD28(-), CD28(low), CD28(int), and CD28(high) peripheral blood human CD4(+) T cells were defined using three-color flow cytometry. The three CD28(+) subsets displayed a one-, two-, or threefold quantitative difference in their relative number of CD28 antibody binding sites, respectively (P < 0.01). RA patients, whether active or inactive, showed a distinct phenotype when compared to healthy donors: (i) the percentage of CD4(+)CD28(high) cells was increased twofold and the CD4(+)CD28(low) subset was reduced twofold (P < 0.01) and (ii) the CD4(+)CD28(high) cells from RA patients showed an in vivo activated phenotype, CD45RO(+)CD5(high)IL-2Ralpha(+) (P < 0.01). Active RA patients were different from inactive patients. They showed a twofold increase in mean CD28 expression (P < 0.05), whereas each of the CD28(+) subsets in the inactive RA patients showed reduced expression when compared to healthy donors. Notably, both active and inactive RA patients showed abnormal CD28 upregulation when T cells were activated in vitro with CD3 antibodies, but only inactive RA patients showed a hypoproliferative response to TCR/CD3 triggering when compared to healthy donors (P < 0.01). This defective proliferation was normalized by concurrent crosslinking with CD28 antibody. No differences were noted in the expression of CD152 or CD80, a CD28 and CD152 shared ligand. The disregulated in vivo expression of CD28 was related to the RA patients' disease activity and suggests that modulation of CD28 surface levels may be an additional mechanism to finely tune the delicate responsiveness/tolerance balance.

Arthritis, Rheumatoid↗

PubMed2000

Effect of silicon supplement on osteopenia induced by ovariectomy in rats.

The effect of silicon (Si) supplement on preventing bone mass loss induced by ovariectomy (OVX) in rats was investigated. Three groups of 15, 100-day-old female Wistar rats each, with a mean initial weight of approximately 260 g per animal, were selected for the present study. One of the experimental group consisting of 15 OVX rats was fed a diet supplemented with 500 mg of Si per kg of feed (Si + OVX). The other two groups consisting of 15 OVX and 15 sham-OVX rats did not receive these supplements. Morphometric (weight and length) and densitometric studies with dual-energy X-ray absorptiometry were performed on the whole femur and 5th lumbar vertebra of each animal 30 days after the experiment. The Si + OVX rats did not show a loss of bone mass induced by OVX at axial level (5th lumbar vertebra) or periphery (femur). Nonetheless, a significant increase (ANOVA with Bonferroni/Dunn post hocs test) of longitudinal development of the femur (P < 0.0001) was patent. These results, obtained through the measurements of axial and peripheral bones, warrant closer scrutiny in connection with the Si inhibitory effect on bone mass loss as well as the stimulatory effect on bone formation. Both actions, namely, inhibition of resorption and stimulation of formation, infer that Si may have a potential therapeutic application in the treatment of involutive osteoporosis.

Absorptiometry, Photon↗

PubMed1999

Effects of alprazolam supplementation on vertebral and femoral bone mass in rats on strenuous treadmill training exercise.

The ability of alprazolam to diminish cortisol response and favor ovarian function could make it useful in the prevention of osteopenia in athletes in selected cases. A sample of 45 female Wistar rats, all 93 days old and with a mean initial weight of 267 +/- 17 g, were studied. Rats were exposed to a high-performance level of exercise and were divided into two groups-one group received an alprazolam supplement and one did not-and compared with controls to determine the effect of alprazolam on bone mass as measured by dual-energy X-ray absorptiometry (DKA). Exercise consisted of treadmill running on 5 out of 7 days during a period of 11 weeks. A steep grade treadmill inclination was used to stimulate high-intensity muscle activity. Final inclination was 17.5 degrees and treadmill speed was 45 cm/second. Upon completion of the experiment, all the rats were killed and the femur and 5th lumbar vertebra were dissected and cleaned. Length, weight, bone mineral content (BMC), and density (BMD) of the whole right femur and 5th lumbar vertebra were measured. In the exercise only group (no alprazolam), the length, weight, BMC, BMD, and femur BMC/final rat weight ratio of the femur, and the vertebral weight, vertebral BMD and BMC, and vertebral BMC/final rat weight ratio were lower than in the control and the exercise-alprazolam groups (P < 0.0167 - < 0.0001). Alprazolam preserves bone mass in rats exposed to intense exercise.

Absorptiometry, Photon↗

PubMed1999

Effects of potassium bicarbonate supplementation on axial and peripheral bone mass in rats on strenuous treadmill training exercise.

We administered a potassium bicarbonate supplement to rats on strenuous treadmill training in order to determine the effect on bone mass and the metabolic acidosis seen with this type of training. A sample of 45 93-day-old female Wistar rats with a mean initial weight of 267 +/- 17 g were studied. The control group (15 rats) was not exercised or given potassium bicarbonate (Ex- PB-). The experimental group (30 rats) was randomly divided into two subgroups of 15 rats each, one that exercised and did not receive potassium bicarbonate (Ex+ PB-) and one that exercised and received potassium bicarbonate (Ex+ PB+), at a dose of 0.05 mg/kg/day administered by esophageal catheter on exercise days. Training consisted of treadmill running on 5 out of 7 days for a period of 11 weeks. Running time, treadmill speed, and the percent grade were gradually increased until week 7, then maintained until rats were sacrificed at the ened of 11 weeks. The bone mineral content (BMC) and bone mineral density (BMD) of the whole right femur and 5th lumbar vertebra were measured. Femoral and vertebral length were also measured. Femur length, weight, BMC, and BMD, and femur BMC/final weight ratio, and vertebral weight, BMD, and BMC, and vertebral BMC/final weight ratio were lower in the Ex+ PB- group than in either the controls or the Ex+ PB+ group (P < 0.01-P < 0.0001); the length of the 5th lumbar vertebra did not differ between groups.

Animals↗

PubMed1997

Total body bone measurements in spinal osteoporosis by dual-energy X-ray absorptiometry.

Changes in total body bone mineral content (BMCTB) and density (BMDTB), and the T-score of BMCTB and (BMDTB) were evaluated in relation to the number of vertebral fractures in women with postmenopausal osteoporosis for the purpose of defining deviations in these parameters that could be predictive of the occurrence of vertebral fracture. The study group consisted of 62 women diagnosed with postmenopausal osteoporosis. All of them had two or more spinal fractures. Regression analysis of the number of fractures against each parameter studied indicated that the following were predictive of the risk of fracture: a reduction of -0.5 in the T-score of both BMCTB and BMDTB (P < 0.0001) and a loss of about 135 g of BMCTB or 0. 058 g/cm2 of BMDTB (P < 0.0001). The fact that such changes were found during the follow-up of women with osteoporosis highlights the importance of bone mass measurements during follow-up.

Absorptiometry, Photon↗

PubMed1997

Influence of weight and gonadal status on total and regional bone mineral content and on weight-bearing and non-weight-bearing bones, measured by dual-energy X-ray absosorptiometry.

OBJECTIVE: To evaluate the influence of weight on total body bone mineral content (BMCTB) and regional body bone mineral content (head, arms, trunk and legs). This was studied in accordance with gonadal status and the weight-bearing or non-weight-bearing status of each region. METHODS: The study included 94 postmenopausal women (mean age 60.6 +/- 10.5 years), 36 perimenopausal women (mean age 49.0 +/- 2.3 years) and 60 premenopausal women (mean age 36.1 +/- 6.9 years). Full-body bone densitometry (DXA), for measuring total body bone and regional bone mineral content, was carried out in all the women. RESULTS: Among these groups, the influence of 1 kg of body weight on total and regional bone mineral content (percent) did not differ (paired test P ns). In the overall group of women, paired comparison showed differences between the head and other zones measured (P = 0.036-0.004). In the overall group of women, no differences were found in the percent influence of 1 kg body weight on bone mineral content in any study zone (by ANOVA, Fisher's PLSD post hoc test and the Kruskal-Wallis test). In the overall group of women, Fisher's r to z test revealed a non-significant relationship between weight and the bone mineral content of the head (r = 0.49, P ns) but in every other region the relationship between weight and bone mineral content was significant (r = 0.36-0.54, P < 0.0001 in all). CONCLUSIONS: The effect of body weight on BMCTB and regional did not differ significantly with either gonadal status or weight-bearing (legs) and non-weight-bearing bones (arms).

Absorptiometry, Photon↗

PubMed1992

Septic arthritis in patients with acquired immunodeficiency syndrome with human immunodeficiency virus infection.

We have evaluated the presence and characteristics of septic arthritis in intravenous (iv) drug users with human immunodeficiency virus (HIV) infection. Sixteen patients with both HIV infection and septic arthritis were studied and compared with 5 patients with septic arthritis but no HIV infection. Clinical profile, laboratory findings at the time of onset, localization, causative organisms, mean hospitalization time and presence of complications were the same in HIV positive and HIV negative patients. Staphylococcus aureus was the most commonly isolated organism in both groups. We conclude that septic arthritis in HIV infected iv drug users is not uncommon, it is produced by the same organisms and presents similar characteristics to the ones found in iv drug users without HIV infection. Therefore, the presence of HIV infection does not appear to modify the characteristics of septic arthritis.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Penicillin--intermediate-resistant pneumococcal spondylodiscitis.

Pneumococcal osteomyelitis probably was more common in the pre-antibiotic era, but currently is rare. Sickle-cell disease and possibly, bone trauma and advanced age are predisposing factors for pneumococcal osteomyelitis. Bone infection usually occurs as a result of hematogenous spread from an infective focus, which often cannot be identified. In patients without evidence of other focci of infection, pneumococcal spondylodiscitis probably is caused by "primary" pneumococcal bacteriemia, originating in the oropharynx, especially if the patient has alterations that disrupt the oropharyngeal mucose. Whereas early in the antibiotic era, all Streptococcus pneumoniae strains were susceptible to penicillin, resistance to this antibiotic is on the rise, and in many parts of the world, it has emerged as a major problem. We report the case of a young patient with penicillin-resistant pneumococcal vertebral and intervertebral disk disease who had no evidence of pneumococcal infection elsewhere, and we discuss the possible mechanism of infection. We also review briefly the resistance to penicillin of S. pneumoniae and the treatment of choice.

Adolescent↗