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Biomedical subjects

L Fajardo

Publications and source records attributed to L Fajardo.

At least 19 recordsLinked to original sources
PubMed2001

Three-dimensional optical tomographic imaging of breast in a human subject.

We present for the first time a full three-dimensional (3-D) reconstruction of absorption images of breast from continuous-wave (cw) measurements performed on a premenopausal woman. Our 3-D optical images clearly reveal a large primary tumor as well as a small secondary tumor in a separate location of the breast. The multiple tumors identified by our 3-D optical imaging have been confirmed by the subsequent biopsy examination of the breast. Quantitative information of the optical images obtained is provided in terms of the location, size, and absorption coefficient of the tumors.

Biopsy↗
PubMed2000

[(99m)Tc]-sestamibi parathyroid scintigraphy in chronic haemodialysis patients: static and dynamic explorations.

BACKGROUND: The place of parathyroid gland imaging by [(99m)Tc](technetium)-sestamibi scintigraphy in uraemic patients with secondary hyperparathyroidism remains a matter of debate. The purpose of the present study was (i) to assess its value with respect to plasma intact parathyroid hormone (iPTH) levels and to surgical parathyroidectomy (PTx), and (ii) to explore the possibility of suppressing parathyroid [(99m)Tc]-sestamibi uptake by calcitriol. METHODS: In a first cross-sectional, static study 52 chronic haemodialysis (HD) patients with plasma iPTH levels between 14 and 2791 pg/ml (normal, 10-65 pg/ml) had a [(99m)Tc]-sestamibi scan, and 21 of them underwent surgical PTx. In a second longitudinal, dynamic study 14 chronic HD patients with advanced secondary hyperparathyroidism received short-term calcitriol treatment in an attempt to suppress [(99m)Tc]-sestamibi imaging of parathyroid glands. Calcitriol was given intravenously for 2 weeks, 2 microg after each haemodialysis session. Scintigraphy was carried out before and at the end of this inhibition test. RESULTS: [(99m)Tc]-Sestamibi scan led to imaging of one or more (maximum three) parathyroid glands in most, but not all, HD patients with plasma iPTH values >600 pg/ml. Based on surgical findings, overall sensitivity of [(99m)Tc]-sestamibi scan in correctly locating parathyroid glands was only 50%, whereas specificity was 100%. In contrast, its sensitivity was 100% in locating single glands in the subgroup of five patients with recurrent hyperparathyroidism. The calcitriol inhibition test showed suppression of [(99m)Tc]-sestamibi uptake by at least one parathyroid gland in eight patients (57%), with complete suppression in five of them (36%). Basal plasma iPTH or decrease of plasma iPTH in response to calcitriol was not predictive of suppressible [(99m)Tc]-sestamibi uptake in the individual case, although mean iPTH was markedly higher in patients with non-suppressible parathyroid glands. CONCLUSION: Because of its relatively low sensitivity the [(99m)Tc]-sestamibi scan is of limited help in the exploration of uraemic patients with severe secondary hyperparathyroidism before a first surgical PTx. However, it is very useful in locating the remaining parathyroid gland(s) in case of reoperation. The novel calcitriol inhibition test of [(99m)Tc]-sestamibi uptake could help to better distinguish parathyroid glands with non-suppressible, autonomous activity from glands whose activity might be amenable to long-term suppression.

Calcitriol↗
PubMed1999

Clinical and pathologic overlap in nonsteroidal anti-inflammatory drug-related small bowel diaphragm disease and the neuromuscular and vascular hamartoma of the small bowel.

Diaphragm disease (DD) is a radiographically subtle cause of small bowel obstruction and is part of the spectrum of diseases associated with nonsteroidal anti-inflammatory drug injury. The neuromuscular and vascular hamartoma (NMVH) is a nonepithelial hamartomatous, submucosally based proliferation of mature submucosal elements capable of causing small bowel obstruction. The authors report two patients in whom the clinical setting and gross pathology are that of DD, but the histologic characterization is identical to that described for NMVH. It is probable that in some patients the two diseases overlap so that some patients readily fit the criteria for both entities.

Aged↗
PubMed1998

Are there any differences in the parathyroid response in the different types of renal osteodystrophy?

With the purpose of studying the curve of parathyroid response to variations of serum calcium during dialysis, we studied 20 patients on haemodialysis: 10 women and 10 men, with different forms of bone disease diagnosed by bone biopsy (adynamic bone disease, mild hyperparathyroidism, severe hyperparathyroidism). In all patients, we performed parathyroid stimulation by 4 h dialysis with 1 mEq/l of Ca2+ in the dialysate, and an inhibition test in another dialysis session with 4 mEq/l of Ca2+, with a 48 h interval. Ca2+ and intact parathyroid hormone (iPTH) were measured prior to dialysis and every hour subsequently, to obtain a Ca2+-iPTH for each patient. The analysis of the curves was made using Brown's four-parameter model. Stimulation and inhibition levels were similar in all groups, but basal iPTH and the response profiles obtained varied in the different histological groups. Basal, maximal and minimal iPTH were lower in adynamic forms than in the other two groups (P<0.04), and basal calcium was higher than basal calcium of severe hyperparathyroidism, expressing a basal inhibition status. In severe hyperparathyroidism, basal calcium was lower than the set-point, showing a permanent stimulation, and the slope was higher than in other groups, showing more sensitivity to serum calcium variations. The set-point of severe hyperparathyroidism was significantly higher than the set-point of mild and adynamic forms. In conclusion, the functional parathyroid study showed a different response in the different forms of renal osteodystrophy.

Adult↗
PubMed1998

Can we use 99mTc-MIBI in functional studies of the parathyroid gland?

The usefulness of technetium-99m-sestamibi (99mTc-MIBI) in patients with secondary hyperparathyroidism on haemodialysis was assessed. We studied 33 patients with parathyroid scintigraphy with i.v. (99mTc-MIBI). Static images in a scintillation camera were taken at 15 and 120 min after the injection. With P x Ca<80, we performed an inhibition test with calcitriol i.v. 2 microg, three times a week, for 2 weeks. The MIBI study and assessment of intact parathyroid hormone (iPTH) were performed before (baseline study) and after inhibition. A 'focal positive study' corresponded to one or more areas of abnormal hypercaptation in relation to surrounding thyroid tissue seen in early images and persisting in later images, and a 'negative study' did not correspond to the previous image. In the baseline study, iPTH in the positive MIBI group was significantly greater than in the negative group. Eight positive MIBI patients had a bone biopsy; six corresponded to severe osteitis fibrosa and two to mild osteitis fibrosa. In the negative MIBI group, four of the six patients who had bone biopsy had mild forms of osteitis fibrosa (Fisher=0.03); the other two had low turnover forms. A positive inhibition test was defined when the basal uptake disappeared after calcitriol administration. In these patients, we observed a significant decrease of iPTH, not observed in the negative inhibition test. In 10 patients who had been parathyroidectomized, those with alpha positive basal MIBI result had a nodular parathyroid hyperplasia. We conclude that a scintigraphic parathyroid study with 99mTc-MIBI showed a good correlation with functional parathyroid status. With the same inhibition test, only some glands were inhibited, suggesting that this could be the expression of different vitamin D receptor densities in inhibited glands and/or a different kind of proliferation in those glands. This test would be of value in functional studies when a therapeutic decision must be made.

Adult↗
PubMed1996

Percutaneous core biopsy of the breast: effect of operator experience and number of samples on diagnostic accuracy.

OBJECTIVE: The purpose of our study was to assess the degree of operator experience and the number of core biopsy samples required to achieve an accurate histologic diagnosis for each of five common mammographically defined lesions, using percutaneous core breast biopsy performed on a dedicated prone biopsy table. SUBJECTS AND METHODS: A prospective multisite study was performed that involved nine institutions (academic and private) with experienced breast radiologists and the use of dedicated prone biopsy table units with digital assistance and standardized protocol. Asymptomatic women evaluated during a 2-year study period were assigned a mammographic diagnosis reported in a manner prescribed by the American College of Radiology Breast Imaging Reporting and Data System lexicon. Mammographic lesions evaluated included masses, masses with calcifications, clustered calcifications, focal asymmetries, and architectural distortions. Where histologic diagnosis was indicated, core biopsy was performed with five individual samples obtained and sequentially analyzed. Two hundred thirty patients had immediate excisional biopsy, the results of which provided the basis for a statistical analysis to compare the accuracy of each sequential core biopsy sample with surgical results. Statistical analysis was also done to ascertain the accuracy of core biopsy diagnosis as a function of operator experience. RESULTS: Trends toward increasing accuracy were observed by increasing the number of core biopsies for each of five types of mammographically defined lesions, especially for clustered calcifications. Statistically significant increased accuracy was observed when the number of biopsies was increased beyond one (p = .003). Trends toward increased accuracy with more experience were observed for all lesions, especially for calcifications. Of the 230 lesions studied with immediate surgical validation, more than 80% of all lesions except clustered calcifications (75%) were diagnosed on the basis of two core biopsies; accuracy after five biopsies was 98% for masses, 91% for calcifications, 100% for masses with calcification, 100% for focal asymmetries, and 86% for architectural distortions. CONCLUSIONS: Accuracy of diagnosis based on the results of percutaneous core breast biopsy improved with an increase in the number of core biopsy samples obtained for any given lesion seen on mammograms and with increased experience in performing the procedure. Five samples yielded an overall diagnostic accuracy of 97%. Familiarity with expected accuracy from this procedure for different mammographic lesions and following increased experience may assist physicians in planning patient management.

Analysis of Variance↗
PubMed1994

Use of antithrombin III in critical patients.

OBJECTIVE: To evaluate the effect of the AT III concentrates upon the clinical evolution and hemostatic parameters. DESIGN: Prospective, open, randomized trial. PATIENTS AND PARTICIPANTS: Septic and multiple trauma patients admitted to our Intensive Care Unit. SETTING: Levels of AT III below 70% were used as criteria to choose 36 patients, 20 of whom received treatment with AT III and 16 did not. INTERVENTIONS: AT III concentrates were administered at an initial dose of 60 U/kg followed by 10 U/kg every six hours. RESULTS: The administration of AT III neither contributes to alterations in haemostasis, nor the clinical evolution (evaluated according to Apache II score). CONCLUSIONS: The results suggest that the administration of AT III concentrates to critical patients with acquired low levels, but without manifest DIC, may not be justified; although further studies on a larger population are required to establish definite conclusions.

APACHE↗
PubMed1990

The effect of lipid composition on the relaxivity of Gd-DTPA entrapped in lipid vesicles of defined size.

The effects of lipid composition on the relaxivity of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) entrapped in lipid vesicles has been examined for vesicles of different sizes composed of egg phosphatidylcholine and cholesterol in various molar ratios, as well as the stability of those same vesicles in human serum at 37 degrees C. It is found that the incorporation of cholesterol decreases the apparent relaxivity of the entrapped Gd-DTPA, concomitant with an increase in vesicle stability in serum. Cholesterol has little effect on relaxivity when incorporated at ratios up to 20 mole percent, but has an increasing effect at higher mole percentages. These results correlate with the known effects of cholesterol on the osmotic water permeability coefficients of various model membrane systems and suggest that it is the water flux across the vesicle bilayer that is limiting to the T1 relaxivity of the entrapped Gd-DTPA. The incorporation of up to 20 mole percent cholesterol has little effect on the stability of the vesicles in serum, whereas vesicles containing more than 20 mole percent cholesterol show greater increases in stability. It was also found that the stability of vesicles depends upon the size of the vesicles; smaller vesicles are less stable in human serum at 37 degrees C than larger vesicles.

Blood↗
PubMed1990

From food basket to food security. The food factor in nutritional surveillance.

One important indicator of nutritional surveillance is the one devoted to monitor food security. The experience toward the development of one of such indicators is presented. This includes the development of a food basket, defined as the group of foods that meet the characteristics such as is now consumed by important population segments of the community; it contributes a substantial portion of the calories and proteins purchased, and is responsible for an important proportion of the food budget. The concept implies a dynamic food basket, the quantities of which are calculated in a way that simulates the behavior of the consumer and the best nutrition knowledge. For this purpose we use linear program techniques. A measure of the risk of being unable to buy the foods needed for a family is presented, and is used as a proxy for food security risk. In the appendix, the mathematical expressions of the model used for a linear program is also presented.

Colombia↗
PubMed1983

Fat necrosis of the breast simulating recurrent carcinoma after primary radiotherapy in the management of early stage breast carcinoma.

Between March 1973 and December 1980, 76 patients with Stage I or II breast carcinoma were treated by biopsy and definitive radiation therapy at Stanford University Medical Center. There were 78 treated breasts since two patients had bilateral carcinomas at presentation. During a median follow-up period of 29 months, eight patients developed discrete masses in the treated breast. In four of these patients biopsied tissue revealed recurrent carcinoma yielding a local control rate of 95%. Four additional patients had lesions which were clinically indistinguishable from recurrent cancer. Biopsy specimens, however, revealed fat necrosis of the breast. The clinical and pathologic features of this entity are described. It is imperative that clinicians be aware of this treatment sequelae so that conservative diagnostic procedures may be used and breast deformity minimized. If postirradiation fat necrosis is considered, mastectomy for suspected persistent or recurrent disease may be avoided.

Biopsy↗
PubMed1975

Protein requirements of man: comparative nitrogen balance response within the submaintenance-to-maintenance range of intakes of wheat and beef proteins.

Sixteen young male students participated in two studies designed to determine the nitrogen balance response to beef or stone-ground, whole wheat protein over the submaintenance-to-maintenance range of protein intake. The objective of the studies was to evaluate the relative capacities of these proteins to meet the minimum protein needs in young adult males. A modified Latin-square design was used to allocate subjects to the four 15-day metabolic balance diet periods in each study. The last 10 days were used for fecal nitrogen determination and the last 5 days for evaluation of urinary nitrogen excretion. The diet periods were separated by a 4-day break period and began with 1 day on a "protein-free" diet. The levels of protien (N times 6.25) intake tested were 0.2, 0.3, 0.4, and 0.5 g/kg body weight/day in the beef study. The results have been compared with those obtained in a previous similar study with egg protein. The regression of estimated "true" nitrogen balance (Y) (mg N/kg/day) on nitrogen intake (X) (mg N/kg/day) was: Y equals 0.51(plus or minus 0.08)X minus 41.9(plus or minus 4.6) for beef and Y equals 0.27(plus or minus 0.06)X minus 33.6(plus or minus 5.0) for whole wheat protein. The amounts of beef and wheat proteins estimated to be requried to support body nitrogen balance in 97.5% of the population supplied 96 and 178 mg N/kg/day, respectively. The relative protein value of beef and wheat proteins, in comparison with egg protein, was 78 plus or minus 12 and 41 plus or minus 10, respectively. It is concluded that the variations in dietary protein quality should be taken into account in assessing the protein adequacy of diets for individuals and population groups.

Adolescent↗
PubMedDate not supplied

Acute respiratory tract infections among a birth cohort of children from Cali, Colombia, who were studied through 17 months of age.

For this study, 340 children less than 18 months old from a low-income, urban neighborhood in Cali, Colombia, were observed from birth by means of weekly home visits to detect cases of acute respiratory tract infection. All suspected cases were confirmed by trained doctors in a special clinic. Information on symptoms, signs, and potential risk factors was documented prospectively. Etiologic agents were identified in cases of lower respiratory tract infection (LRI). The overall incidence of acute respiratory tract infection was 6.6 cases per child-year at risk. The incidence of upper respiratory tract infection was 4.9 cases per child-year at risk and that of LRI was 1.7 cases per child-year at risk. Crowding in the home was found to be significantly associated with an increased incidence of LRI. Respiratory syncytial virus was the viral agent most frequently isolated from cultures of nasopharyngeal aspirates of children with LRI. Staphylococcus aureus was the bacterial agent most frequently isolated from the blood of patients with LRI.

Acute Disease↗