Biomedical subjects

J Beltran

Publications and source records attributed to J Beltran.

At least 37 records · Page 2Linked to original sources

PubMed1998

Hepatic blood flow and oxygen extraction ratio during normothermic recirculation and total body cooling as viability predictors in non-heart-beating donor pigs.

BACKGROUND: Our aim was to evaluate the hepatic blood flows and oxygen metabolism of non-heart-beating donor (NHBD) pigs, with the use of cardiopulmonary bypass (CPB) and normothermic recirculation (NR) before total body cooling, and its relationship with recipient survival. METHODS: Thirty-five pigs were transplanted with an allograft from NHBDs. After warm ischemia (WI) time (20, 30, or 40 min), CPB and NR were run for 30 min. After this period, the animals were cooled to 15 degrees C. In the control group (20 min of WI), the period of NR was excluded. Liver procurement was then performed. RESULTS: Survival rate was 100% in the 20WI, 70% in the 30WI, and 50% in the 40WI. Control group survival rate was 0%. Hepatic artery blood flow and portal blood flow recovered during NR. Pump blood flow during CPB increased rapidly during NR and was significantly higher in the 20WI. When donors of the livers transplanted in "surviving pigs" (DSP) were compared with donors of the livers transplanted in "nonsurviving pigs" (DNSP), hepatic artery blood flow, portal blood flow, and pump blood flow were higher in the DSP. Hepatic oxygen extraction ratio increased in the three groups with respect to baseline values. Hepatic oxygen extraction ratio was lower in the 20WI than in the other groups and was lower in the DSP than in the DNSP. CONCLUSIONS: The use of a NR period before total body cooling improves survival of liver transplantation in NHBDs. Portal blood flow and pump blood flow measurements can predict the viability of the grafts.

Animals↗

PubMed1998

Solid-phase microextraction for quantitative analysis of organophosphorus pesticides in environmental water samples.

Solid-phase microextraction (SPME) is a relatively new technique that appears as a convenient and efficient extraction method in contrast with more complex techniques used for pesticide residue analysis based on liquid-liquid and solid-phase extraction. This extraction procedure involves the absorption of analytes into a polymeric film coated onto a fine silica fiber directly dipped in the aqueous sample. An SPME procedure for the determination of 12 organophosphorus pesticides in clean environmental water samples at low ng/ml concentration level has been developed by optimising variables involved in extraction and desorption. The absorption equilibrium has been estimated by mathematical treatment of the process using an expression that describes experimental absorption time profiles. The method was evaluated according to the reproducibility, linearity range and limits of detection using two different fiber coatings: 100 microm polydimethylsiloxane and 85 microm polyacrylate. The limits of detection obtained using nitrogen-phosphorus detection ranged between 0.01 and 0.2 ng/ml with relative standard deviations lower than 15% at the 1 ng/ml level. The method showed good linearity between 0.1 and 10 ng/ml with regression coefficients ranging between 0.97 and 0.999. Determination of organophosphorus pesticides in water samples in concentration below 0.1 ng/ml can be easily carried out with this fast, economic and solvent-free SPME procedure.

Adsorption↗

PubMed1998

Liver conditioning after cardiac arrest: the use of normothermic recirculation in an experimental animal model.

The aim of this study was to compare the possible role of normothermic recirculation with the role of liver transplants from non-heart-beating donor pigs after 20 min of cardiac arrest. Three groups were studied, of which two were control groups: group 1, in which the liver was harvested from a heart-beating donor; group 2, in which the liver was harvested after a period of cardiac arrest followed by total body cooling; and group 3, in which the liver was procured as in group 2, but including a period of 30 min of cardiopulmonary bypass and tissue oxygenation at 37 degrees C before total body cooling. Survival at 5 days; endothelial (hyaluronic acid) and hepatocellular damage (AST, ALT, and alpha-GST); adenine nucleotides (energy charge), and histological changes were evaluated. Normothermic recirculation during 30 min showed a significant effect on survival (p = .03), endothelial damage (p < .05), and histological changes after reperfusion (p = .04). Cardiopulmonary bypass significantly increased the energy charge during the normothermic recirculation period (p = .001). Moreover, this study shows that a significant survival (100%) can be achieved with a liver allograft after 20 min of cardiac arrest. Although the liver suffers a major insult in terms of endothelial damage and hepatocellular damage, lesions caused by the ischemic injury are reversible. Histological changes also indicate lesion reversibility, since they almost disappear after 5 days.

Adenine Nucleotides↗

PubMed1998

Low incorporation of soleus tendon: a potential diagnostic pitfall on MR imaging.

We describe a case of thickening and longitudinal increased signal within the Achilles tendon in a patient denying any recent or previous history of Achilles tendon injury. The MR appearance, while simulating tendinosis or rupture, was compatible with incomplete incorporation of the soleus tendon into the gastrocnemius tendon. This constitutes a normal anatomical variant, not previously described in the radiologic literature, and should not be confused with increased signal and thickening due to disease of the Achilles tendon.

Achilles Tendon↗

PubMed1998

Chondrocalcinosis of the hyaline cartilage of the knee: MRI manifestations.

PURPOSE: To determine the ability of MRI to detect the presence of crystals of calcium pyrophosphate in the articular cartilage of the knee. DESIGN AND PATIENTS: The MR studies of 12 knees (11 cases) were reviewed retrospectively and correlated with radiographs (12 cases) and the findings at arthroscopy (2 cases) and surgery (1 case). A total of 72 articular surfaces were evaluated. Radiographic, surgical or arthroscopic demonstration of chondrocalcinosis was used as the gold standard. Additionally, two fragments of the knee of a patient who underwent total knee replacement and demonstrated extensive chondrocalcinosis were studied with radiography and MRI using spin-echo T1-, T2- and proton-density-weighted images as well as two- and three-dimensional fat saturation (2D and 3D Fat Sat) gradient recalled echo (GRE) and STIR sequences. RESULTS: MRI revealed multiple hypointense foci within the articular cartilage in 34 articular surfaces, better shown on 2D and 3D GRE sequences. Radiographs showed 12 articular surfaces with chondrocalcinosis. In three cases with arthroscopic or surgical correlation, MRI demonstrated more diffuse involvement of the articular cartilage than did the radiographs. The 3D Fat Sat GRE sequences were the best for demonstrating articular calcification in vitro. In no case was meniscal calcification identified with MRI. Hyperintense halos around some of the calcifications were seen on the MR images. CONCLUSION: MRI can depict articular cartilage calcification as hypointense foci using GRE techniques. Differential diagnosis includes loose bodies, post-surgical changes, marginal osteophytes and hemosiderin deposition.

Adult↗

PubMed1998

Chondrosarcoma of the short tubular bones of the hands and feet.

OBJECTIVE: To report 12 cases of chondrosarcoma in a rare location, the short tubular bones of the hands and feet, as well as 12 cases of enchondroma in similar locations, emphasizing the radiologic and histopathologic features. DESIGN AND PATIENTS: All relevant cases that had both histologic slides and radiographs available were taken from the files of one orthopedic referral hospital and the personal files of one of the authors. A similar number of enchondroma cases was selected at random from the files. RESULTS AND CONCLUSIONS: One malignancy arose in a background of enchondromatosis, with all the others being solitary lesions. A pathologic diagnosis of malignancy is often difficult in the absence of radiologic signs of malignancy (cortical destruction with or without soft tissue extension). However, three cases were unusual in that the initial radiograph demonstrated a benign appearance. Another group of three malignancies was surprisingly indolent biologically. The treatment of choice is ray resection (or more limited amputation in a lesion of the middle or distal phalanx).

Adolescent↗

PubMed1998

Prolonged pneumoperitoneum at 15 mmHg causes lactic acidosis.

BACKGROUND: Acute increases in intraabdominal pressure (IAP) induce systemic and regional circulatory changes. Besides, mechanical compression on the capillary beds may decrease oxygen availability to the tissues. The purpose of this clinical study was to analyze the effects of increased IAP on acid-base disturbances and plasma lactate levels during prolonged carbon dioxide pneumoperitoneum. METHODS: Twenty-eight patients undergoing laparoscopic sigmoidectomy were included in this study. Fourteen of them (group A) had IAP of 15 +/- 1 mmHg while the remaining 14 (group B) had IAP of 10 +/- 1 mmHg. The control group included six patients undergoing conventional sigmoidectomy. RESULTS: A progressive significant increase in PaCO2 was observed in the laparoscopic groups (p < 0.01). Plasma lactate levels in group A significantly increased 90 min after insufflation (p < 0.05) and reached the highest value 1 h after deflation (9.9 +/- 1 vs 31.9 +/- 2.5 mg/dl, p < 0.005). Simultaneously, arterial pH decreased in all groups; however, at 1 h after surgery, it was significantly lower (p = 0.02) in group A. There was a significant correlation between acid concentration due to lactate and lactate concentration (GA: R2 = 0.717, p = 0.03; GB: R2 = 0.879, p = 0.006 and GC: R2 = 0.853, p = 0.008). CONCLUSION: High IAP causes lactic acidic accumulation in patients undergoing prolonged laparoscopic procedures.

Acidosis, Lactic↗

PubMed1997

Epiphyseal extension of a unicameral bone cyst.

Epiphyseal extension of a unicameral bone cyst is rare. We report a case of a 13-year-old boy with three pathological fractures through a unicameral bone cyst with epiphyseal involvement in the proximal humerus. These lesions initially tends to expand the humeral epiphysis laterally and progress medially. They also commonly cause a slip of the epiphysis in a medical direction. They also have a greater association with growth retardation and lesser degree of recurrence than their metaphyseal counterpart.

Adolescent↗

PubMed1997

Subperiosteal osteoid osteoma: radiographic and pathologic manifestations.

OBJECTIVE: To demonstrate the radiologic and pathologic manifestations of osteoid osteoma arising beneath the periosteum, on the surface of the bone. DESIGN: One hundred and sixty osteoid osteomas were seen over a 30-year period. The radiologic, pathologic and operative findings of those that were subperiosteal were reviewed. PATIENTS: Eleven patients with subperiosteal osteoid osteoma were reviewed. The patients ranged in age from 13 to 36 years with a mean of 24 years. Eight were male and three were female. RESULTS AND CONCLUSION: Eleven subperiosteal lesions were studied. The reactive periostitis of four lesions was atypical and misleading. Four lesions had features similar to the more common intracortical variety. Three lesions occurring within the joint like other intra-articular lesions were barely seen on plain radiographs. Bone scan and CT scan were virtually diagnostic. The histopathology of these lesions was also atypical though not misleading. In conclusion, subperiosteal osteoid osteoma is a rare lesion with atypical radiographic and histopathologic features. The unusual reactive periostitis seen in several extra-articular cases may suggest other diagnoses.

Adolescent↗

PubMed1997

Os sustentaculi: depiction on MR images.

We describe a 14-year old patient with pain in the medial ankle. The MR study depicted a rare accessory ossicle called the os sustentaculi. This accessory bone should not be confused with a fracture of the sustentaculum tali of the calcaneus.

Adolescent↗

PubMed1997

Peroneus quartus muscle: MR imaging features.

PURPOSE: To determine the prevalence of the peroneus quartus (PQ) muscle, to demonstrate the morphology of this accessory muscle on magnetic resonance (MR) images, and to reassess the reported association of the PQ muscle with a hypertrophic peroneal tubercle. MATERIALS AND METHODS: A retrospective review was performed of 136 consecutive ankle MR imaging studies. The origins, insertions, and variations in size of the muscle and the dimensions of the peroneal tubercle and retrotrochlear eminence were recorded. RESULTS: The prevalence of the PQ muscle was 10% (14 of 136 cases). The accessory muscle and tendon unit descended medial and posterior to the peroneal tendons. The site of insertion was variable and included the calcaneus, peroneus longus tendon, peroneus brevis tendon; and cuboid bone. The calcaneus was the insertion site in 11 cases. The accessory tendon attached to the retrotrochlear eminence of the calcaneus. In the group with the PQ muscle, the retrotrochlear eminence was significantly taller (P < .01) than in the group without the PQ muscle. CONCLUSION: Contrary to previous reports, the peroneocalcaneal variant of the PQ muscle appears to insert in the retrotrochlear eminence of the calcaneus rather than the peroneal tubercle. The presence of the PQ muscle is associated with a prominent retrotrochlear eminence but not with an enlarged peroneal tubercle.

Adolescent↗

PubMed1997

Anterior horn of the lateral meniscus: another potential pitfall in MR imaging of the knee.

PURPOSE: To demonstrate that speckled increased signal intensity at the anterior horn of the lateral meniscus near its central attachment site on sagittal magnetic resonance (MR) images of the knee is a normal finding. MATERIALS AND METHODS: In 22 patients (17 male and five female patients; age range, 13-74 years; mean, 38 years) who underwent arthroscopy after MR imaging, knee MR images that showed speckled increased signal intensity at the anterior horn of the lateral meniscus near its central attachment site on two consecutive sagittal proton-density-weighted images were selected for retrospective review. In addition, a review of 11 knee MR examinations of nine healthy volunteers (five men and four women; age range, 27-43 years; mean, 34 years) was performed. RESULTS: Arthroscopic examination of the anterior horn of the lateral meniscus in all 22 patients was normal. Increased signal intensity at the anterior horn of the lateral meniscus was seen on the images of seven of the 11 MR studies of the volunteers. CONCLUSION: Increased signal intensity at the anterior horn of the lateral meniscus near its central attachment site on knee MR images does not represent a meniscal tear.

Adolescent↗

PubMed1997

MR features of longitudinal tears of the peroneus brevis tendon.

OBJECTIVE: Our objective is to describe the characteristic MR imaging features of longitudinal tears of the peroneus brevis tendon and to describe pathologic conditions and normal variants that are associated with these tears which may require surgical intervention at the time of primary tendon repair. MATERIALS AND METHODS: We retrospectively reviewed 10 MR images of asymptomatic volunteers and 31 MR images of 27 patients with evidence of longitudinal splits of the peroneus brevis tendon. Seven of these cases were surgically proven. In addition, we assessed five pathologic conditions and normal variants: lateral collateral ligamentous tears; injuries to the superior peroneal retinaculum; low-lying muscle belly of the peroneus brevis tendon; peroneus quartus muscle; and convex, flat, or irregular retromalleolar groove. RESULTS: In the patient's group, we saw longitudinal splits as clefts and an irregularity of the contour of the peroneus brevis tendon with (71%) and without (29%) signal changes on proton density-weighted and T2-weighted MR imaging sequences. Divisions of the split tendon assumed a characteristic C-shaped configuration that partly enveloped the peroneus longus tendon. Fifteen cases revealed other pathologic conditions and normal variants known to be associated with or to predispose to tears of the peroneus brevis tendon. These include ankle ligamentous tears (n = 3); abnormal superior peroneal retinaculum (n = 4); low-lying muscle belly of the peroneus brevis tendon (n = 1); peroneus quartus muscle (n = 2); and convex, flat, or irregular retromalleolar groove (n = 15). MR imaging revealed tears in all patients with surgical proof (n = 7). CONCLUSION: MR imaging is a useful technique for revealing longitudinal tears of the peroneus brevis tendon as well as showing anatomic and pathologic factors associated with or predisposed to tears.

Adult↗

PubMed1997

Alterations in the distal extension of the musculus peroneus brevis with foot movement.

OBJECTIVE: A low-lying belly of the musculus peroneus brevis (presence of muscle tissue within the fibular groove) is said to be a risk factor for rupture or dislocation of the peroneal tendons. However, alterations in foot position may affect the position of the musculotendinous junction. The purpose of this study was to evaluate the normal position of the musculotendinous junction of the musculus peroneus brevis in full dorsiflexion and plantar flexion. MATERIALS AND METHODS: The ankles of 12 adult asymptomatic volunteers were imaged in full dorsiflexion and plantar flexion. The number of scans between the fibular groove and the first scan imaging the muscle belly of the musculus peroneus brevis was documented in each patient in full dorsiflexion and plantar flexion. RESULTS: Distal extension of muscle belly into or beyond the fibular groove was present in 11 subjects in dorsiflexion and in seven subjects in plantar flexion. CONCLUSION: Extension of the muscle belly of musculus peroneus brevis into and distal to the fibular groove is part of the normal excursion of the muscle during foot motion. Care should be taken not to misdiagnose this normal finding as a pathologic condition when interpreting MR studies of the ankle.

Adult↗

PubMed1997

The peroneocalcaneus internus muscle: MR imaging features.

OBJECTIVE: The peroneocalcaneus internus muscle is a rare muscle of the posterior calf that to our knowledge has not been reported in the radiology literature. The purpose of our study was to describe the normal anatomy and MR characteristics of this muscle in eight patients in whom the muscle was identified. CONCLUSION: The peroneocalcaneus internus muscle is a rare muscle that originates from the inner aspect of the distal fibula, descends within the tarsal tunnel, and inserts on a small tubercle in the calcaneus, just distal to the sustentaculum tali. The muscle may displace the flexor hallucis longus muscle medially and thus indirectly encroach on the neurovascular bundle.

Adolescent↗

PubMed1997

MR imaging of dislocation of the posterior tibial tendon.

OBJECTIVE: The purpose of this article is to describe the MR imaging appearance of seven cases of posterior tibial tendon dislocation and subluxation. CONCLUSION: Posterior tibial tendon dislocation is a rare but important entity usually related to a previous traumatic event. The clinical diagnosis is often missed because of its rarity. MR imaging provides important clues to the diagnosis and preoperative evaluation of this condition.

Adult↗

PubMed1997

MR imaging of normal variants and interpretation pitfalls of the elbow.

Discrimination of normal anatomic landmarks from true disease is one of the fundamental tenets of adept MR imaging. The radiologist is thus compelled to accumulate a comprehensive knowledge of normal structures, variants, and potential MR imaging interpretation pitfalls. In this article the authors focus on a number of normal, bony, ligamentous, and tendinous structures that can simulate disease at the elbow. A discussion of the particular anatomy responsible for the appearance of each of these interpretation pitfalls is provided. In addition, ways to distinguish these pitfalls from true elbow disease are discussed.

Diagnosis, Differential↗

PubMed1997

MR features of nerve disorders at the elbow.

MR imaging is a useful method for evaluating nerve disease. It can portray the normal anatomy and identify unsuspected space-occupying masses. Severe intrinsic nerve disease can be depicted. This article outlines the normal anatomy of the three major nerves that traverse the elbow joint: the ulnar nerve, the median nerve, and the radial nerve. Entrapment and compression neuropathies of each nerve are discussed in detail. Finally, the role of MR imaging in delineating each nerve abnormality is examined.

Elbow Joint↗