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Biomedical subjects

T V Sanchez

Publications and source records attributed to T V Sanchez.

At least 19 recordsLinked to original sources
PubMed1997

Bone densitometry of proximal femur in Chinese subjects: gender differences in bone mass and bone areas.

Bone mineral content (BMC), bone areas (BA), and bone mineral density (BMD) of the proximal femur were measured in 202 healthy Chinese men and 507 healthy Chinese women, aged 21-70 years, to investigate gender differences in densitometry of the femur. Densitometric values measured at the femoral neck, trochanter, and Ward's triangle were generally greater in men than women of the same age, except at Ward's triangle. While BMD decreased with aging with similar slopes of -0.2 approximately -1% per year, the actual readings were 10%-15% lower than those of Caucasian subjects of the same age and gender for Chinese men and women. Furthermore, with increasing age, trochanteric BA increased in women but not in men, and femoral neck BA increased in men but not in women. These different trends of change in bone dimensions were independent of weight or height. They may reflect a structural difference at the proximal femur and imply differences in mechanical strength, and thus may have played some roles in the different incidence of hip fractures between the elderly men and women.

Absorptiometry, Photon↗
PubMed1997

Effect of bone area on spine density in Chinese men and women in Taiwan.

Areal bone mineral density (BMD), the quotient of bone mineral content (BMC) divided by the projectional bone area (BA), measured with dual-energy X-ray absorptiometers (DXA), is the most common parameter used today to evaluate spinal osteoporosis. To evaluate whether gender, age, weight, and height can determine spinal BA, and to compare BA and analyze its effects on spinal density in the two genders, we measured BA and BMC, and calculated areal BMD, and the bone mineral apparent density (BMAD = BMD/the square root of BA) of the L-2 to L-4 vertebrae of 604 female and 223 male Chinese volunteers from 20 to 70 years of age using a Norland XR-26 DXA. Standardized for height and weight, BA showed a relatively large variation and a significant increase with increasing age in both genders. On the other hand, BMC stayed unchanged in men > 50 years of age and decreased with aging in postmenopausal women. Younger men (< 51 years) had a much larger mean BA (by 15.5%) and larger mean BMC (only 10%) than that of age-matched women. As a result, younger men had a slightly and significantly lower areal BMD (by 7.1%) and a much lower BMAD (by 16%) (p < 0.0001 for both) than premenopausal women of similar age. Men had higher areal BMD and BMAD values than age-matched women only after age 50 years. Although taller body height, heavier weight, and increasing age were associated with a larger BA, these factors could not explain most of the interindividual variations in BA in both genders. Thus anteroposterior BA of lumbar vertebrae measured with DXA seems to affect the areal BMD and BMAD readings in the two genders. The larger BA caused a low BMAD and probably underestimated the true volumetric spine density in men.

Absorptiometry, Photon↗
PubMed1997

Osteopenia induced by long-term, low- and high-level exposure of the adult rat to lead.

The skeleton, the major site for Pb accumulation, is responsible for the largest fraction of the total body burden, but long-term effects of low-level exposure in adults remain unclear. In this study rats were exposed to low (0.01%; 100 ppm, LoPb) or high (0.5%, 5,000 ppm, HiPb) Pb, low calcium, feeding regimes for 1-12 months. Both LoPb and HiPb animals showed significant 12-month blood Pb levels [LoPb 21 +/- 3 micrograms/dl; HiPb 59 +/- 18; controls 3 +/- 1 (mean +/- SEM), p = 0.001]. Dual energy X-ray densitometry of the femur detected a significant decrease in bone density in HiPb animals by 3 months which remained significantly lowered through 12 months [3 months: HiPb: 0.498 +/- 0.011 (6) vs. control: 0.546 +/- 0.012 (6), p < 0.003]. By 12 months' density was also significantly lowered in LoPb animals (p = 0.001). Mineral analyses of ashed femurs showed a significant lead content after 1, 3, 9 and 12 months' exposure [1 month: LoPb, 0.020 +/- 0.002 (4) (% ash weight) vs control 0.008 +/- 0.0004 (4); HiPb 0.016 +/- 0.001 (8); control 0.007 +/- 0.0004 (6) (p < or = 0.002)]. Ca levels (% ash weight) were significantly lowered at 9 months in HiPb and 12 months in both groups (p < or = 0.04). Quantitative histomorphometry documented significantly elevated osteoid and resorptive trabecular surface features in both Pb groups. The LoPb design produced no overt renal functional abnormalities and resulted in blood Pb values comparable to those in man with modest environmental Pb exposure. The HiPb design resulted in development of lead nephropathy (more severe from months 6-12) and produced blood lead levels comparable to those seen in past industrial exposure. Findings show that Pb is incorporated into bone mineral after only 1 month's exposure to LoPb with significant osteopenia after 12 months' exposure; HiPb caused osteopenia by 3 months. No normal compensatory mechanism was elicited to maintain bone mass. Results stress renewed concern about the effects of cumulative, low-level lead exposure in our elderly population.

Absorptiometry, Photon↗
PubMed1988

Vegetarian lifestyle and bone mineral density.

The amount and type of dietary protein affect bone mineral loss after the menopause. This observation was substantiated in 10 y of studies by direct photon absorptiometry, four results of which follow. 1) Studies of 1600 women in southwestern Michigan revealed that those who had followed the lactoovovegetarian diet for at least 20 y had only 18% less bone mineral by age 80 whereas closely paired omnivores had 35% less bone mineral. 2) A study of self-selected weighed food intake showed no statistical difference in nutrient intakes but a difference in Ca:P ratio and acid-base formation of diet, each significant to p less than 0.001. 3) When sulfur intake of a fixed diet was increased, the titratable acidity of the urine increased proportionately. 4) Bone mineral densities of 304 older women from the continental United States closely paralleled those from earlier Michigan studies.

Adult↗
PubMed1985

The effect of lactation on the mineral distribution profile of the rat femur by single photon absorptiometry.

The distribution of bone mineral in excised femurs from lactating and nonlactating control rats was localized and quantitated using single photon absorptiometry. Bone mineral content was measured proximodistally in nine sequential 0.32 cm increments along the femur length and then plotted as a function of the distance from the proximal end of the femur. The plots described a mineral distribution profile and revealed that bone loss following lactation was site specific, being greater in the metaphyseal regions (23-36%) than in the diaphyseal area (14-20%). The change in total bone mineral of femur caused by lactation was estimated by integrating the mineral distribution profile plots. The 28% lower bone mineral determined by this method was in close agreement with the 27% difference determined from femur dry weight measurements. Reproducibility of measurements with 10 repositionings of a single femur was within 4% at all but the 2 most distal sites. Variation in the estimated total bone mineral was 1.3%.

Animals↗
PubMed1983

Bone mineral mass in adult lacto-ovo-vegetarian and omnivorous males.

Past studies indicate postmenopausal women who eat meat may experience greater bone mineral loss than lacto-ovo-vegetarian women. The present study extends those findings by comparing bone mineral in adult lacto-ovo-vegetarian and omnivorous males. Bone mineral mass was determined by direct photon absorptiometry in 320 lacto-ovo-vegetarian and 320 omnivorous males 20 to 79 yr old. Lacto-ovo-vegetarians were Seventh-day Adventists committed to their diet for at least 20 yr. Measurements were made at a cortical site along the radius. No statistical differences were identified between bone mineral mass in the lacto-ovo-vegetarian and omnivorous males in any decade examined. When contrasted against significant differences between bone mineral mass in postmenopausal omnivores and lacto-ovo-vegetarians, the data presented here may be interpreted as indicating that some factor associated with meat consumption is increasing bone mineral losses in postmenopausal females while having no observable effect in males.

Absorptiometry, Photon↗
PubMed1981

Bone mineral analysis of the rat femur by direct photon absorptiometry.

This report describes a method using direct photon absorptiometry (DPA) for determination in vivo of the bone mineral content to bone width ratio (BMC/W) in the rat femur. A significant correlation was noted between measurements by DPA and whole femur dry weight and ash weight. Measurements were reproducible within repeated determinations of both the same and successive days. Soft tissue, rotation of the femur, or slight differences in the longitudinal positioning of the femur did not significantly affect usefulness of the measurements. A significant positive correlation was seen between body weight and the femur BMC/W, indicating that the method accurately reflected expected physiological changes in bone mineral. The method is suitable for the rapid, simple, accurate, and reproducible measurement of bone mineral in the anesthetized rat and is applicable to serial measurements.

Animals↗
PubMed1981

Peritoneal clearance of theophylline.

Clearance of theophylline was determined in 3 patients receiving maintenance theophylline during peritoneal dialysis. The average peritoneal dialysis clearance of theophylline was 11.67 ml/min. The average theophylline to creatinine clearance ratio was 0.85 representing significant clearance across the peritoneum. The amount of theophylline removed per exchange was approximately 8 mg. Charcoal or resin hemoperfusion and hemodialysis are undoubtedly the most efficient means of treating theophylline overdose. However, peritoneal dialysis appears to be a useful alternative as overdosed patients would be expected to have significantly higher serum concentrations than encountered in this study, greater gradients across the peritoneal membrane, and greater net removal of theophylline per exchange than reported here.

Aged↗
PubMed1981

Determinants of tissue aluminum concentration.

These data taken together might indicate that increased tissue burdens of aluminum begin early in chronic renal disease as a consequence of oral aluminum administration. The initiation of dialysis leads to additional aluminum exposure via dialysate. Elevated endogenous parathyroid hormone levels could further enhance the absorption of orally ingested aluminum and alter tissue distribution of aluminum resulting in high brain aluminum concentration.

Aluminum↗
PubMed1980

Parathyroid hormone-mediated aluminum deposition and egress in the rat.

Exogenous PTH significantly enhances tissue aluminum concentration in normal rats fed an aluminum-supplemented diet. In this study, we examined the effect of PTH withdrawal on brain and whole carcass aluminum concentrations. Four groups of rats were fed an aluminum diet while receiving injections of PTH for 5 days. On day 5, one group of rats was sacrificed, and the treatment regimen of the remaining groups altered. PTH, the aluminum diet, or PTH and the aluminum diet were withdrawn respectively for an additional 5 days. An additional group of rats was fed the aluminum diet for 10 days. PTH dramatically increased the concentration of aluminum in both brain and carcass above that found in tissues of rats given aluminum alone. Brain and whole carcass aluminum concentrations remained elevated in rats continued on PTH even in the absence of continued supplemental dietary aluminum. In contrast, following PTH withdrawal, brain and whole carcass aluminum concentrations were significantly lower and independent of dietary aluminum. Thus, PTH may be an important mediator of specific tissue aluminum burdens.

Aluminum↗
PubMed1980

Cortical bone density of adult lacto-ovo-vegetarian and omnivorous women.

Lacto-ovo-vegetarian women fifty to eighty-nine years of age lost 18 per cent bone mineral mass while omnivorous women lost 35 per cent. This study established that this difference could not be explained by a greater bone density in the lacto-ovo-vegetarians during the third, fourth, and fifth decades of life. The possibility of higher sulfur content in the meat-containing diet, the effect of excess phosphorus, and the effect of an acid-ash diet are discussed. From the standpoint of a general survey, comsumption of calcium-containing foods was not appreciably different in the two groups. It is, therefore, concluded that lacto-ovo-vegetarian diet may be beneficial in extended protective health care in terms of defense against, or control of, bone mineral loss in the later years of a woman's life.

Adult↗
PubMed1979

Noninvasive measurement of bone mineral mass in the unanesthetized rabbit.

Direct photon absorptiometry was used for the in vivo measurement of bone mineral mass in the rabbit tibia. Bone mineral mass in 124 male and female rabbits was correlated (p less than 0.001) with age to 26 weeks and weight to 5.5 kg. Examining reproducibility and repositioning error, three rabbits were measured 12 times each. Bone mineral mass in the three rabbits was: 0.432 +/- 0.020 g/cm2, 0.414 +/- 0.010 g/cm2 and 0.487 +/- 0.037 g/cm2. The greatest coefficients of variance observed for measurements without repositioning and measurements with repositioning were 4.8% and 7.6%, respectively. The technique provided sensitive, reproducible and noninvasive measurement of bone mineral mass without anesthesia or undue restraint.

Age Factors↗
PubMed1978

Factors affecting tissue aluminum concentration.

Elevated concentration of aluminum has been reported in serum, whole blood and tissue samples of patients with renal insufficiency. Evidence incriminating aluminum as a neurotoxin among the dialysis population is strong. The source of this aluminum has not been clearly defined, although both gastrointestinal and parenteral routes may be involved. Data from this laboratory suggest that an effect of parathyroid hormone on tissue aluminum burdens may, in part, explain why only certain patients exposed to high dialysate aluminum develop the dialysis encephalopathy syndrome and the occasional occurrence of this syndrome in the absence of dialysis or increased dialysate aluminum.

Administration, Oral↗
PubMed1976

The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. I. Sexual dimorphism in the distribution of antennal sense organs in five species.

Sexual dimorphism in the distribution of antennal sense organs is common among adults of the genus Periplaneta. In three out of the four strains of Periplaneta americana examined, adult males had more contact chemoreceptros than females. In the fourth strain of P. americana and in P. australasiae, P. brunnea, P. fuliginosa, and P. japonica, no statistically supportable sexual dimorphism of contact chemoreceptors was found. However, in all strains and species of Periplaneta examined, sexual dimorphism was found in the total number and/or density of olfactory sensilla. Male adults had nearly twice as many olfactory sensilla as female adults. These observations are consistent with the behavioral observation that males within the genus Periplaneta rely on the reception of an airborne pheromone for the initiation of courtship behavior. In P. americana, where sexual dimorphism was found in the contact chemoreceptors, contact stimuli release the full wing raising display and presentation in males during courtship.

Animals↗