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PubMedDate not supplied

Assessment of physician responses to abnormal results of bone densitometry studies.

OBJECTIVE: To assess how physicians who have ordered bone densitometry studies respond to abnormal results. METHODS: We conducted a retrospective review of cases from physicians affiliated with a community teaching hospital. The study sample consisted of 142 female patients with abnormal bone mineral density (BMD) who had been referred by 50 physicians (internists or gynecologists). A questionnaire was completed for each patient, providing data about further investigations, treatment interventions, and frequency of referral to a specialist in bone diseases. RESULTS: Of the patients diagnosed with osteoporosis on the basis of BMD studies, 20.4% had no further investigations, and 27.8% underwent only mammography. Of all the patients with osteoporosis, 10.6% received no therapy (calcium and vitamin D excluded). The majority of all patients (71.8%) received a combination of calcium and vitamin D. The most common treatment modality was hormone replacement therapy. The second most common treatment strategy was bisphosphonates. The percentage of all referrals to specialists in metabolic bone diseases was low--11.3% in the patients of internists and 14.5% in the patients of gynecologists. CONCLUSION: In this study, the information provided by bone densitometry did not affect management in a substantial percentage of patients. A considerable percentage of patients underwent no further investigations to rule out secondary causes of osteoporosis.

Aged↗

PubMed2000

[Comparative evaluation of bone mineral density in Mexican women using x-ray bone densitometry and ultrasound].

With lifestyle changes in women, smoking and use of beverages with caffeine, and sedentarism increasing, so the risk factors for decalcification, increase; which is a public health problem by the higher incidence of osteoporotic fractures, as the age advances, specially in the postmenopause woman, which means a greater secondary morbidity-mortality; an important cause of physical disability, which directly affects psychoemotional wellbeing in women. In this study two methods of bone densitometry, were used; one of x ray, and other with ultrasound in 138 women during postmenopause with an average index of corporal mass of 29. Both results were compared of bone density, T measurement with osteopenia and osteoporosis. Double densitometry, was done in the 138 patients of lumbar spine with DEXA equipment, and of calcaneum with DTU-one equipment, by the same technician, finding the difference of T punctuation in this double study.

Absorptiometry, Photon↗

PubMedDate not supplied

Rapid identification and quantification of chlorpheniramine maleate or pheniramine maleate in pharmaceutical preparations by thin-layer chromatography-densitometry.

Thin-layer chromatography (TLC)-densitometry was used to separate, identify, and quantitate chlorpheniramine maleate (CPM) and pheniramine maleate (PM) when present in combination with other drugs in pharmaceutical preparations of tablets, syrups, eye and ear drops, etc. CPM or PM was extracted (tablets, capsules, etc.) or diluted (liquid preparations, if needed) with 80% ethanol and isolated from other ingredients by TLC on silica gel G using cyclohexane-chloroform-methanol-diethylamine (4.5 + 4.0 + 0.5 + 1.0, v/v) as the mobile phase. Separated CPM and PM were detected under shortwave ultraviolet light and quantitated by scanning densitometry at 260 nm. Recoveries of CPM and PM were 100.09+/-0.77% and 100.09+/-0.87%, respectively.

Chlorpheniramine↗

PubMedDate not supplied

[Value of bone densitometry for the diagnosis and monitoring of osteoporotic patients: integration with biological and clinical risk factors].

The diagnosis of osteoporosis and the monitoring of antiosteoporosis therapies imply a better and more rational use of bone densitometry. The optimal prescription modalities of this fundamental examination are favorably correlated with the efficacy of modern therapeutics. The rationale of this article is to provide the general practitioner with a factual update on the diagnostic and prognostic use of bone densitometry.

Aged↗

PubMedDate not supplied

Quantitative analysis of phenobarbital in dosage form by thin-layer chromatography combined with densitometry.

In this paper, a high-performance thin-layer chromatography (HPTLC) method combined with densitometry has been described. Chromatography was performed on silica gel Si 60F254 plates using dichloromethane-ethyl acetate-formic acid (9.5 +/- 0.5 +/- 0.1, v/v) mobile phase. This method has been successfully applied for the determination of phenobarbital in pharmaceuticals. Obtained results were comparable with traditionally used column high-performance liquid chromatography (HPLC) methods. For the proposed procedure, linearity (r > 0.999), sensitivity (limit of detection 0.4 microg/spot), recovery (97.8-102.1%), and repeatability were found to be satisfactory. The HPTLC-densitometry method has many advantages, such as simplicity, reasonable sensitivity, rapidity, and low cost, and it can be successfully used in routine quality control of multidrug preparations containing barbiturates.

Acetates↗

PubMed1991

Rod densitometry in the aging human eye.

Retinal densitometry is a noninvasive physiologic technique used to examine the visual pigments in living human eyes. To assess possible age-related disturbances of rod photopigment kinetics, retinal densitometry was done in 44 eyes of 44 healthy subjects (age range, 12-78 yr). With progressing age, a significant but small increase in photopigment density difference (bleached versus dark adapted eye) and an increase in the time constant of rhodopsin regeneration was found. The increased density difference in rods was consistent with morphologic findings of increased rod outer segment diameter and disc content in older subjects. To explain this change in terms of the decreased specular reflections at the level of the inner limiting membrane was inadequate because age effects were independent of wavelength in the region of 450-550 nm. To control for the effects of ocular stray light from the lens, subjects older than 40 yr with a clear crystalline lens were measured and compared with those with pseudophakia. No statistically significant difference was found between the two groups. Increased rod density difference contrasts sharply with an earlier reported decrease in this parameter for foveal cones. The slowing of the regeneration rate is a phenomenon common to rods and cones. It may be a result of a gradual metabolic dysfunction of the retinal pigment epithelium in older subjects.

Adolescent↗

PubMed1990

A study of variance in densitometry of retinal nerve fiber layer photographs in normals and glaucoma suspects.

The main object of this research was to develop a reliable method of screening glaucoma suspects and patients for early loss of or changes in the retinal nerve fiber layer (RNFL). This study quantifies the variances due to photography, digitizing, and analysis of red-free photographs of the RNFL. The influence of pupil size, optic disc position and eye movements, film processing, digitizing, and intra- and interphotographic-session and intra- and interoperator variances were established. It was found that pupils needed to be dilated to at least 6 mm, that the optic disc had to be positioned in a standardized area in the negative, that the head of the subject had to remain still during photography, and that film processing and digitizing of the negative needed to be strictly controlled to minimize the variance in collection of densitometry data from RNFL red-free photographs. It was established that focusing of the negatives during digitization was not crucial. Criteria were defined for acceptable negatives. Interphotographic-session and intraoperator variances were not significant in most cases when negatives were digitized to these criteria. Analysis of interphotographic-session variance showed that there were still some factors in photography, film processing, and/or image digitizing that were not sufficiently controlled for long-term follow-up without normalization of the data. Densitometry data gathered using the established protocol, from negatives of 71 subjects were analyzed; best sensitivity and specificity rates of 80% and 100%, respectively, were achieved for the diagnosis of glaucoma.

Adult↗

PubMed1990

[Determination of body fat by means of densitometry and anthropometry in children 6 to 10 years of age].

The authors have studied the body composition in a group of 36 boys from 7 to 10 years old, through densitometry and anthropometry. They have found significant correlations between the percentage of fat, got by densitometry and some anthropometric indices: Quetelet index (r = 0.79), sum of 4 skinfolds (r = 0.78) and logarithm of the sum of 4 skinfolds (r = 0.80). After a multiple regression analysis, they got equations which permit you to calculate the percentage of fat, using several anthropometric parameters with a 10% of error. They bring two nomograms which facilitate the estimation of body fat. They compare the results obtained with the ones described by others authors and suggest the need to extend this study to boys with other ages as well as to girls.

Anthropometry↗

PubMed1990

Innovative approaches to noninvasive bone densitometry.

In conclusion, this review has endeavored to familiarize the practicing radiologist with some of the newer approaches to noninvasive bone densitometry that are currently being explored as potential improvements over existing techniques. Three-dimensional volumetric CT is a practical means of measuring bone density in the proximal femur, owing to the widespread availability of the necessary scanning equipment, and affords enhanced prediction of biomechanical parameters in the spine and hip, but suffers from limitations similar to those of conventional quantitative CT. Dual-energy projection radiography offers significant potential advantages over dual-photon absorptiometry from the standpoint of precision, radiation dose, image quality, and examination time, but remains to be thoroughly tested. Compton scattering appears to be a viable alternative to single-photon absorptiometry for bone density determinations in the peripheral skeleton. Neutron and proton activation analysis are unlikely to achieve widespread application, owing to their cyclotron-dependent nature, although the former will probably remain the optimal means for determining total body calcium. Experience with scanning-slit fluorography and magnetic resonance as applied to noninvasive bone densitometry is currently too limited to permit prediction of their ultimate role in this respect. As a final point, it should be noted that major incentives for mobilization of bone densitometric equipment currently exist: on Earth, as a means of facilitating patient access and saving money via joint ventures, and in space for monitoring the adverse effects of weightlessness on skeletal mass and the ability to function following return to a gravity environment.

Bone Density↗

PubMed1989

Retinal densitometry in acute posterior multifocal placoid pigment epitheliopathy.

Cone photopigment kinetics were investigated by retinal densitometry in six patients with acute posterior multifocal placoid pigment epitheliopathy (APMPPE). Our goal was to document the course of cone impairment during a period of at least 12 months following the onset of the disease process. During the active stage, we found that the amount of pigment measurable by densitometry (the density difference) was reduced and that the time constant of pigment regeneration was unmeasurable. Following resolution of the fundus lesions, the densitometric parameters gradually improved in eight of ten eyes. In patients who maintained foveal fixation (five eyes), the density difference and the time constant of pigment regeneration improved simultaneously, though with individual differences in time course. Photopigment kinetics returned to normal in all these patients but the density difference remained lower than normal in four of the five eyes. In patients with parafoveal fixation (five eyes), photopigment kinetics were slow, possibly reflecting mixed cone and rod contributions. With time, the density difference improved to a level comparable to that measured in normal observers at a similar retinal location, but the photopigment regeneration time constant remained abnormal or unmeasurable. Recovery was variable, with one eye changing from parafoveal to foveal fixation, and no improvement noted in two eyes with extreme parafoveal fixation. Our findings demonstrate a large interpatient variation associated with APMPPE.

Color Perception↗

PubMed1986

Densitometry and microchromatography compared for determination of the hemoglobin C and A2 proportions in hemoglobin C and hemoglobin SC disease and in hemoglobin C trait.

Using both densitometry and anion-exchange microchromatography, we measured hemoglobin C (Hb C) and Hb A2 proportions in 11 patients, eight of whom had Hb AC, two Hb SC, and one Hb CC. For one patient with Hb SC, we made the determinations before and after a transfusion. The mean (and SD) for the sum of Hb C + Hb A2 by densitometry and anion-exchange microchromatography for the nine patients with Hb AC and Hb CC were 45 (18) and 40 (18)%, respectively (p greater than 0.1, r = 0.98); for the three determinations involving the two Hb SC patients, the respective proportions were 40 (9.9) and 38 (6.6)% (r = 0.88). Electrophoretic analysis of microchromatographic eluates from the Hb AC and Hb CC patients showed that 6% of the absorbance of the late high-ionic-strength eluate was due to Hb C, which was responsible for the statistically insignificant difference between densitometric and chromatographic values for Hb C + A2 values. Electrophoresis on cellulose acetate of concentrated eluates of the Hb C + A2 fraction from the two Hb SC patients revealed no contamination by Hb S. Evidently, microchromatography can be used to determine Hb C + A2 in patients with Hb C or Hb SC disease or Hb C trait.

Anemia, Sickle Cell↗

PubMed1983

Analysis of brain lipids by high performance thin-layer chromatography and densitometry.

We have devised a high performance thin-layer chromatography (HPTLC) densitometry method to resolve the major lipid classes of brain tissue. We used DEAE-Sephadex column chromatography to separate the total lipid into neutral and acidic lipid fractions. The lipid fractions were then spotted on separate HPTLC plates and chromatographed in one dimension using two solvent systems. Quantitation was by in situ densitometry with absolute amounts of the lipid classes determined from co-chromatographed standards. An internal standard was also used to improve the precision. The individual lipid classes of rat whole brain, human brain gray and white matter, rat and bovine myelin, and bovine oligodendroglia were quantitated. Human brain phosphatidylethanolamine plasmalogen was also quantitated. Sensitivity was increased by using the cupric acetate charring reagent, which we found to be more sensitive than the conventional sulfuric acid-dichromate reagent. Total lipid (less than 400 micrograms) was quantitated from 5 mg of tissue wet weight. The limit of detection, on HPTLC, for the individual lipid classes was below 20 ng.

Animals↗

PubMed1995

[Contribution of osteo-densitometry in the definition and diagnosis of osteoporosis].

Since its first characterisation, osteoporosis has always been defined on an anatomical basis. The term osteoporosis refers to a reduction (or atrophy) in the amount of bone tissue and to microarchitectural deterioration without any mineralisation defect. Its clinical significance lies in the fractures (vertebral fracture, Colles' fracture and hip fracture) that occur spontaneously or after a minimal trauma. During the past 15 years, developments in technology of bone mass measurement (osteodensitometry) currently allow a diagnosis of osteoporosis at its anatomical stage characterised by a reduction in bone mass (osteopenia) without any symptom. A definition based on densitometry offers the major advantage of an early diagnosis, well before the development of fractures. It has been validated recently by several prospective studies which have confirmed the close relationship between the decrease in bone mass and the fracture risk. This modern densitometric approach of osteoporosis has major therapeutic implications. Indications of curative treatments of osteoporosis has major therapeutic implications. Indications of curative treatments of osteoporosis should be reconsidered according to the contribution of bone densitometry.

Absorptiometry, Photon↗

PubMed1994

[Evaluation of surviving fraction using non-clonogenic staining densitometry method].

This study was performed to compare our nonclonogenic survival assay (densitometry assay, DM assay) with the widely used clonogenic assay. The established cell lines (HeLa, RMUG, IMR, GOTO) were grown in F 10 medium. The cells were spread in 24-well plates, irradiated with different doses, cultured for about one week and stained with crystal violet after the culture period. Taking the transparent images of the stained well on the light source with the CCD camera, the images were collected with the matrix size 64 x 64, and the integrated optical density of the entire surface of each well was determined by computer with our original program. As the number of cells in the well is reflected by its staining density, the surviving fraction was calculated as the fraction of growth in the irradiated wells relative to controls. The survival curves obtained by the densitometry method showed good correlations with those obtained by clonogenic assay. It is possible to predict intrinsic radiosensitivity with this assay, even if the cells do not form good colonies. However, this method is based on measurements in cultures which depend on the metabolism and growth kinetics of the irradiated cells. Cells should grow exponentially in the same manner in any well to obtain a result similar to that of clonogenic assay, although growth kinetics may be altered by irradiation. Thus, the endpoint must be strictly standardized.

Cell Survival↗

PubMedDate not supplied

Associated problems of protein electrophoresis, staining and densitometry.

The process of electrophoresis, a separation phenomenon, is mistakenly understood to include the sequential processes ancillary to analyte resolution, that is, staining and quantification, where the latter could be elution followed by photometry or integrating-calculating-densitometry. The theories involved in electrophoresis itself are well worked out and equally well understood but the problems which are associated with separation, chemical reaction to generate a chromogen and quantification, perhaps partly forgotten and perhaps partly ignored, are taken up and described here. They include albumin trail, resolution, unequivalent staining, prestaining and the densitometry problems associated with band widths, opacity effects and polychromaticities.

Blood Proteins↗

PubMedDate not supplied

Densitometry-based equations for estimating body composition in Fischer rats.

Male Fischer rats are widely used to evaluate the effects of nutritional repletion or deprivation on the rat's nutritional status. Practical methods are needed to evaluate changes in body composition. Chemical analysis is expensive, time consuming, and often not available; bioelectrical impedance analysis in laboratory animals lacks standardization. Postulating that the measurement of densitometry would allow reliable estimation of body composition in the male Fischer rat, we studied 27 male Fischer rats. Densitometric measurements of the carcasses and their chemical analysis were performed to obtain reference values. Initial estimation of the fraction of body fat based on densitometry was attempted with the Siri equation intended for use in humans. We found that this equation was not suitable for use in the male Fischer rat because it underestimated fat mass at high carcass weights and overestimated fat mass at low carcass weights. Therefore, the Siri equation was modified to more accurately predict carcass composition in the male Fischer rat. Three different predictive equations based on simple densitometric measurements were developed that allow separate estimation of carcass fat, carcass water, and carcass protein in the male Fischer rat. These equations were found to be accurate to within 2-5-3% of carcass weight.

Adipose Tissue↗

PubMed1977

Computer densitometry for angiographic assessment of arterial cholesterol content and gross pathology in human atherosclerosis.

Sequential change studies in human atherosclerosis are desirable in disease regression trials but are now limited by dependence on the occurrence of epidemiologic end-points. Prior radiographic studies have pertained to advanced obstructive atherosclerosis. This is a study of measures applied by computer-generated densitometry of angiograms to assess early to advanced nonobstructive atherosclerosis. Measures are based on pathologic and angiographic appearance of all stages of atherosclerosis and include image edge roughness, local width, and local contrast density changes. Femoral angiograms were made in 21 cadavers under simulated clinical conditions, with a pressurized radiopaque casting material. Full-size color photographs were made of 10 cm. segments of opened artery, with matching cast and arterial specimens analyzed for cholesterol content. Four graders, on two occasions, sequenced the photographs in increasing order of disease on the basis of the International Atherosclerosis Grading scheme. The correlation between the two sessions was 0.93. Thirteen computer indices correlated significantly with visual grade and cholesterol and were allowed to compete in a step-wise regression for best indices of prediction. Computer index correlation coefficient for visual grade prediction was 0.86, and for cholesterol content, 0.84. Computer densitometry measurement appears useful in the evaluation of all stages of atherosclerosis as recorded angiographically and obviates the necessity for exacting visual comparisons of large numbers of films.

Angiography↗

PubMedDate not supplied

Rapid identification and quantitation of clotrimazole, miconazole, and ketokonazole in pharmaceutical creams and ointments by thin-layer chromatography-densitometry.

Thin-layer chromatography (TLC)-densitometry was used to separate, identify, and quantitate clotrimazole, miconazole, and ketokonazole (alone or combined with other drugs) in various pharmacopoeial or proprietary creams and ointments. Clotrimazole was extracted from the cream or ointment with ethyl alcohol, and miconazole and ketokonazole were extracted with a mixture of equal volumes of chloroform and isopropyl alcohol. Active ingredients were separated from excipients and other drugs by TLC on a precoated silica gel F254 plate with a solvent system of n-hexane-chloroform-methanol-diethylamine (50 + 40 + 10 + 1, v/v). The 3 azoles were well separated and easily identified in this chromatographic system. The separated azoles were visualized under short-wave UV light and quantitated by scanning densitometry at 220 nm by comparing the integrated areas of samples with those of standard (one azole was used as internal standard for the other). Recoveries from samples spiked with known amounts of azoles were excellent. The method was validated further by comparison with official liquid chromatographic methods.

Antifungal Agents↗