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Biomedical subjects

L M White

Publications and source records attributed to L M White.

At least 19 recordsLinked to original sources
PubMed1999

Primary leiomyosarcoma of bone.

OBJECTIVE: This study describes radiographic and MR imaging features of primary leiomyosarcoma of bone. SUBJECTS AND METHODS: Twelve patients (five men and seven women, 39-79 years old) who were treated at two oncology centers for primary leiomyosarcoma of bone involving the femurs, tibia, ilium, and inferior pubic ramus were studied. None of the patients had preexisting disease or disease elsewhere at the time of diagnosis. Pathologic diagnosis was obtained in all patients. RESULTS: Radiographs of all patients showed a matrix that was exclusively osteolytic. In long bones (seven patients), the tumor had an average length of 11 cm (range, 7-17 cm) and revealed an elongated configuration. In the pelvis (five patients), the average length of the tumor was 10 cm (range, 4-15 cm). MR imaging confirmed an intramedullary lesion in all patients, with extension into the soft tissues in eight patients and no identifiable soft-tissue mass in the remaining four patients. Four of the five pelvic tumors had a prominent soft-tissue mass, whereas only four of the seven long bone lesions revealed a soft-tissue mass that was, in all instances, small. The tumor was hypointense on T1-weighted images and showed heterogeneous signal intensity on T2-weighted conventional and fast spin-echo sequences. We saw low signal intensity (short T2) in eight patients and homogeneous hyperintense signal intensity in one patient. In the remaining three patients, T2-weighted spin-echo sequences obtained with fat saturation showed high signal intensity (long T2) in the tumors. CONCLUSION: Primary leiomyosarcoma of bone is a rare tumor that on radiography reveals no matrix and on MR imaging reveals areas of T2 shortening in relation to fat on conventional and fast spin-echo sequences.

Adult↗
PubMed1998

Interstitial duplications of chromosome region 15q11q13: clinical and molecular characterization.

Duplications of chromosome region 15q11q13 often occur as a supernumerary chromosome 15. Less frequently they occur as interstitial duplications [dup(15)]. We describe the clinical and molecular characteristics of three patients with de novo dup(15). The patients, two males and one female (ages 3-21 years), had nonspecific findings that included autistic behavior, hypotonia, and variable degrees of mental retardation. The extent, orientation, and parental origin of the duplications were assessed by fluorescent in situ hybridization, microsatellite analyses, and methylation status at D15S63. Two patients had large direct duplications of 15q11q13 [dir dup(15)(q11q13)] that extended through the entire Angelman syndrome/Prader-Willi syndrome (AS/PWS) chromosomal region. Their proximal and distal breaks, at D15S541 or D15S9 and between D15S12 and D15S24, respectively, were comparable to those found in the common AS/PWS deletions. This suggests that duplications and deletions may be the reciprocal product of an unequal recombination event. These two duplications were maternally derived, but the origin of the chromatids involved in the unequal crossing over in meiosis differs. In one patient, the duplication originated from two different maternal chromosomes, while in the other patient it arose from the same maternal chromosome. The third patient had a much smaller duplication that involved only D15S11 and parental origin could not be determined. There was no obvious correlation between phenotype and extent of the duplication in these patients.

Adult↗
PubMed1998

MR imaging of symptomatic osteochondromas with pathological correlation.

OBJECTIVE: To demonstrate the value of MR imaging in the diagnosis and differentiation of the various symptomatic complications of osteochondromas, providing pathological correlation with emphasis on the usefulness of MR imaging as a single imaging modality in these patients. DESIGN: We retrospectively reviewed all MR examinations of clinically symptomatic osteochondromas (30 patients) performed at our institution between March 1990 and October 1997. PATIENTS: Thirty patients had clinically symptomatic osteochondromas during the study period. Twenty patients were male and 10 were female. There were five cases of multiple osteochondromatosis. Pathological correlation was available in 24 patients. RESULTS AND CONCLUSION: Symptomatic complications included fracture (7%), osseous deformity limiting range of motion (23%), vascular injury (7%), neurological compromise (10%), bursa formation (27%) and malignant transformation (27%). MR imaging was able to diagnose or suggest the etiology for the clinical symptomatology in all cases, demonstrating that it is an ideal imaging modality in the diagnostic evaluation of symptomatic complications of osteochondromas and often avoids the need for further imaging.

Adolescent↗
PubMed1998

Relaxation of imprinting in Prader-Willi syndrome.

We describe two Prader-Willi syndrome (PWS) patients who exhibit maternal uniparental disomy (UPD) of chromosome 15 and unusual patterns of gene expression and DNA replication. Both were diagnosed during infancy as having PWS; however, their growth and development were atypical compared with others with this condition. Weight was below normal in the first patient, and height and development were within normal limits in the second individual. Hyperphagia and polyphagia were not evident in either patient. Genotypes at multiple genomic loci, allele-specific methylation, gene expression, and DNA replication were analyzed at D15S9 [ZNF127], D15S63 [PW71], SNRPN, PAR5, IPW, and D15S10 in these patients. The maternal imprint (based on the absence of gene expression, synchronous replication, and methylation of both alleles) was retained at SNRPN in these patients, as is the case in others with UPD. By contrast, cells from the first individual expressed PAR5 and ZNF127, whereas the second expressed a single IPW allele. Asynchronous DNA replication was observed in both patients at all loci, except SNRPN. These findings show that a subset of imprinted genes can be transcribed in some PWS patients with maternal UPD and that asynchronous DNA replication is coordinated with this pattern of gene expression. Relaxed imprinting in these patients is consistent with their milder phenotype.

Adolescent↗
PubMed1998

Ephedrine pharmacokinetics after the ingestion of nutritional supplements containing Ephedra sinica (ma huang).

Nutritional supplements containing Ephedra sinica (ma huang), a botanical source of ephedrine alkaloids, have been linked to several episodes of ephedrine toxicity and at least 17 deaths, yet these products remain unregulated. Ten subjects were enrolled in a randomized, crossover study aimed at characterizing the pharmacokinetics of ephedrine after the ingestion of three commercially available ma huang products compared with a 25-mg ephedrine capsule. Pharmacokinetic parameters for botanical ephedrine were similar to those for synthetic ephedrine hydrochloride. Gender-based comparisons of Vss/F and CL/F revealed higher values for women than for men (Vss/F, 3.49 +/- 1.04 vs 2.98 +/- 0.73 l/kg; CL/F, 0.48 +/- 0.11 vs 0.37 +/- 0.11 l/hour x kg). The current study suggests that the increased incidence of ma huang toxicity does not stem from differences in the absorption of botanical ephedrine compared with synthetic ephedrine; rather, it results from accidental overdose often prompted by exaggerated off-label claims and a belief that "natural" medicinal agents are inherently safe.

Adult↗
PubMed1998

MR imaging of primary lymphoma of bone: variability of T2-weighted signal intensity.

OBJECTIVE: The purpose of this study was to investigate the MR imaging characteristics of primary lymphoma of bone. MATERIALS AND METHODS: Records of 27 patients with histologic and clinical evidence of primary lymphoma of bone were retrospectively reviewed. Nineteen of these patients underwent MR imaging before surgical biopsy and initiation of therapy. Fifteen of the 19 patients underwent conventional spin-echo T1- and T2-weighted imaging, and the other four patients underwent T1-weighted and fast spin-echo T2-weighted imaging with fat saturation. MR images were separately and independently reviewed by two observers for signal intensity characteristics and homogeneity on T1- and T2-weighted sequences. Signal intensity characteristics were correlated with semiquantitative histopathologic assessments of tumor fibrosis, maturity of fibrosis, and vascularity. RESULTS: T1-weighted signal intensity ranged from isointense to hypointense relative to muscle for all lesions. Twelve of 19 cases showed heterogeneity of signal intensity on T2-weighted images. Predominant tumor T2-weighted signal intensities relative to fat for the 19 patients were assessed as hypointense (observer 1, n = 3; observer 2, n = 1), isointense (observer 1, n = 10; observer 2, n = 11), and hyperintense (observer 1, n = 6; observer 2, n = 7). No correlation among intralesional fibrosis, maturity of fibrosis, or intralesional vascularity and T2-weighted signal intensity characteristics was found. CONCLUSION: T2-weighted MR imaging characteristics of primary lymphoma of bone vary and do not seem to be a simple reflection of histologic findings of intralesional vascularity or fibrosis.

Adipose Tissue↗
PubMed1998

Exclusion of uniparental inheritance of chromosome 15 in a fetus with a familial dicentric (Y;15) translocation.

We present a prenatal case with a 45,X,dic(Y;15) (q11.23;p11.1) karyotype and describe the inheritance pattern of the chromosome 15s. Chromosome 15 has an imprinted region and inheritance of both chromosome 15 from one parent results in either Angelman syndrome (AS) (paternal inheritance) or Prader Willi syndrome (PWS) (maternal inheritance). Parental chromosome studies revealed that the father carried the same dicentric (Y;15) translocation. Since familial chromosome rearrangements can result in aberrant chromosomal segregation during meiosis, we wanted to exclude paternal uniparental inheritance of chromosome 15. By using DNA microsatellite markers at several 15q11q13 loci, we determined that the fetus had inherited his normal non-translocated chromosome 15 from his mother.

Adult↗
PubMed1998

Bone sarcoma diagnosed at the time of reconstructive hip surgery.

OBJECTIVE: To describe the clinical course of a group of patients in whom sarcoma of the proximal femur was diagnosed at the time of reconstructive hip surgery. DESIGN: A retrospective case series. SETTING: Final management of all patients took place at a tertiary care centre. PATIENTS AND INTERVENTIONS: Six consecutive patients with sarcoma of the proximal femur diagnosed at the time of reconstructive hip surgery. The mistaken diagnoses made before surgery were benign tumour (2 patients), avascular necrosis (2 patients), subtrochanteric fracture due to metastasis (1 patient) and granuloma from a loose hip implant (1 patient). The final diagnosis was osteosarcoma in 3 patients and chondrosarcoma in 3. Three patients with high-grade sarcoma received neoadjuvant chemotherapy followed by femoral or pelvic resection, or both, and reconstruction. Two patients with chondrosarcoma underwent wide excision of the tumour with allograft or modular implant reconstruction. One patient with widespread metastasis received only palliative chemotherapy. MAIN OUTCOME MEASURES: Overall survival with respect to oncologic and functional results of treatment. RESULTS: Two patients (1 who received only palliative chemotherapy) died after 5 and 21 months' followup, respectively. Average follow-up for the remaining 4 patients was 65.2 months (range from 51 to 75 months). They were disease free at latest follow-up. One patient required amputation for septic complications related to the reconstruction. CONCLUSIONS: Limb salvage surgery for sarcoma of the proximal femur is challenging when the diagnosis is made at the time of reconstructive surgery rather than through an appropriately planned biopsy. However, this series suggests that limb preservation is feasible and that hindquarter amputation is not the only solution.

Adult↗
PubMed1997

Pharmacokinetics and cardiovascular effects of ma-huang (Ephedra sinica) in normotensive adults.

The purpose of this study was to evaluate heart rate and blood pressure responses to a commercially available source of ma-haung, a natural source of the sympathomimetic substance, ephedrine, and to evaluate the pharmacokinetic properties of the product in normotensive, healthy adults. On day 1, twelve study participants were monitored with an ambulatory blood pressure device between hours 7 and 20. On day 2, they ingested four capsules of powdered ma-huang at hours 8 and 17 while again wearing the monitor between hours 7 and 20. Serial plasma samples were obtained and concentrations of ephedrine were analyzed by high-performance liquid chromatography. Pharmacokinetic parameters of ephedrine were determined from plasma concentration-time profiles. The ephedrine alkaloid content of each capsule was also determined by high-performance liquid chromatography. Six participants experienced a statistically significant increase in heart rate, but the effects on blood pressure were variable. The half-life, volume of distribution, clearance, and maximum concentration in plasma of ephedrine in the ma-huang product were similar to values previously reported for a 20 mg, immediate-release ephedrine tablet. Values for the absorption rate were considerably lower and time to reach maximum concentration was longer for the capsules, compared with the standard tablet. Variability in alkaloid content of ephedrine was low and yielded a mean dose of ephedrine at 19.4 mg; pseudoephedrine at 4.9 mg; and methylephedrine at 1.2 mg for a four-capsule dose. In summary, ma-haung had variable effects on blood pressure and increased heart rate in healthy, normotensive adults. Pharmacokinetic parameters for ephedrine were in agreement with those previously reported; however, the absorption rate was much slower after ingestion of ma-huang.

Adult↗
PubMed1997

Chondroblastoma with multiple distant soft tissue metastases.

A case of metachronous distant soft tissue metastases from a primary rib chondroblastoma, occurring in a 60-year-old man 17 years following resection of the initial lesion, is described. Metastatic chondroblastomas are very rare and almost always involve the lungs. Discussed herein are the clinical, radiologic, and pathologic findings of this unusual case with comparison of our findings to other reports of metastasizing chondroblastomas.

Bone Neoplasms↗
PubMed1997

The effect of training and experience on the magnetic resonance imaging interpretation of meniscal tears.

To evaluate the effects of experience and training in the magnetic resonance imaging (MRI) diagnosis of meniscal tears 30 consecutive patients (60 menisci) in whom MRI of the knee with arthroscopic confirmation of meniscal status were studied. MRIs were interpreted by 10 reviewers of varying levels of training and experience ranging from first-year radiology residents to attending musculoskeletal radiologists. Sensitivity and specificity, and intraobserver variability of MRI interpretation of meniscal tears were calculated for each reviewer and compared to those of readers of the same and varying levels of MRI training and experience. Accuracy (range, 78% to 88%), sensitivity (range, 79% to 88%), and specificity (range, 72% to 94%) results were high, and intraobserver agreement was moderate to high (range, 0.49 to 0.77), in the diagnosis of meniscal tears for all reviewers with 4 or more years of radiology residency training and 3 months of formal MRI experience. In contrast, the accuracy (range, 63% to 82%), sensitivity (range, 58% to 79%), and specificity (range, 58% to 72%) results of reviewers with less experience and training were lower, with higher intraobserver variability. Our results suggest that experience and training play an important role in the accurate and reliable MRI diagnosis of meniscal tears.

Adolescent↗
PubMed1997

Combination of low-dose niacin and pravastatin improves the lipid profile in diabetic patients without compromising glycemic control.

OBJECTIVE: To determine the efficacy and tolerability of the addition of low-dose niacin (1.5 g/d) in a diabetic hypercholesterolemic population who were unable to attain desired lipid control with low-dose (20 mg) pravastatin monotherapy. RESEARCH DESIGN AND METHODS: This was a prospective, open-label study conducted over a 14-week period. Twenty-three diabetic patients with low-density lipoprotein (LDL) cholesterol concentrations of at least 150 mg/dL after dietary therapy were recruited from the outpatient diabetes clinic of a university teaching hospital. After 4 weeks of dietary stabilization and baseline determination of the lipid profile and glycemic control, patients received pravastatin 20 mg once daily for 4 weeks. Laboratory parameters were reassessed and niacin was added to the regimen in qualifying patients. Over 2 weeks, patients' regimens were titrated to a maximal dosage of 500 mg tid. Patients continued to receive the combination regimen for 4 weeks and were reassessed. MEASUREMENTS AND MAIN RESULTS: Sixteen patients (14 non-insulin-dependent diabetes mellitus, 2 insulin-dependent diabetes mellitus) completed the study. Mean fasting blood sugar and fructosamine concentrations were unchanged throughout the study. Five patients required minor alterations (3 increased, 2 decreased) in their hypoglycemic regimens during the study. The addition of low-dose niacin to pravastatin therapy resulted in a significant lowering of LDL cholesterol compared with pravastatin monotherapy. CONCLUSIONS: Low-dose niacin is a promising addition to hydroxymethylglutaryl-coenzyme A reductase inhibitor therapy in the treatment of hypercholesterolemia in patients with diabetes mellitus.

Adult↗
PubMed1997

Arthrographic effect induced by therapeutic ultrasound in magnetic resonance imaging of the wrist: a preliminary investigation.

OBJECTIVE: To evaluate the potential arthrographic effect of therapeutic ultrasound applied before magnetic resonance imaging (MRI) of the wrist. SUBJECTS AND METHODS: MRI of the wrist was performed in 6 asymptomatic volunteers before and after ultrasound therapy of the carpus. For each patient, ultrasound therapy was performed by a trained physiotherapist for 10 minutes, with doses titrated to the maximum tolerated without pain. The amount of fluid within the wrist joints before and after therapy was assessed subjectively by 2 reviewers, as well as objectively by digital analysis. RESULTS: Subjective appraisal of the images indicated that after ultrasound therapy there was an increase in joint fluid within the distal radioulnar joint in 4 volunteers, the midcarpal joint in 4 and the radiocarpal joint in 2. Computerized digital analysis of joint fluid confirmed an average volumetric increase in wrist joint fluid of 52.8% in 3 of the volunteers. The discomfort of the therapy was graded as 1/10 by 5 of the subjects and 4/10 by a single subject. CONCLUSIONS: Therapeutic ultrasound may be a useful adjuvant tool in the noninvasive induction of joint fluid before MRI of the wrist.

Adult↗
PubMed1996

Primary lymphoma of the calcaneus.

Primary non-Hodgkin's lymphoma (NHL) of bone is a rare condition. Presented herein is a case of primary NHL of the calcaneus illustrating many of the classic features of the disease. Emphasized in this report are the nonspecific clinical and conventional radiographic features of primary NHL of bone, which may mimic inflammatory, neuropathic, infectious, or other neoplastic conditions of the extremities. The importance of early cross-sectional radiologic studies, such as magnetic resonance imaging, lies in the early characterization of the mass-like features and local extent of such lesions, helping to raise the suspicion of neoplastic disease.

Aged↗
PubMed1996

Magnetic resonance imaging of the musculoskeletal system. Part 5. The wrist.

Musculoskeletal radiology has been transformed with the advent of magnetic resonance imaging. Magnetic resonance imaging provides visualization of the complex anatomy of the wrist and delineation of numerous pathologic processes, which are difficult to visualize with conventional imaging modalities. With the use of sophisticated pulse sequences and a dedicated extremity coil, magnetic resonance imaging allows evaluation of osseous and ligamentous injuries, arthritides, tumors, and tumor-like conditions. Magnetic resonance imaging techniques will be emphasized and anatomy and various pathologic conditions pertaining to the wrist will be reviewed.

Carpal Tunnel Syndrome↗
PubMed1996

Enlargement of the third intercondylar tubercle of Parsons as a sign of osteoarthritis of the knee: a paleopathologic and radiographic study.

PURPOSE: To correlate presence and size of the third intercondylar tubercle of Parsons (TITP) with occurrence and severity of osteoarthritis of the knee. MATERIALS AND METHODS: In 100 paleopathologic tibial specimens and on 160 clinical knee radiographs, size of the TITP was correlated with osteoarthritis of medical and lateral femorotibial joints (FTJ) and with prominence of tibial spines. RESULTS: TITP size correlated significantly with osteoarthritis of the tibial plateau in the paleopathologic specimens (P<.0001). TITP size correlated significantly with osteoarthritis of medial FTJ and tibial spines on radiographs (P<.0001). Of 85 patients without osteoarthritis of the medial FTJ, 49 (58%) had no TITP, 33 (39%) had small TITPs, and three (4%) had medium or large TITPs. TITPs were found in 15 (88%) of 17 patients with pronounced osteoarthritis. CONCLUSION: Frequency and prominence of TITPs are increased in patients with osteoarthritis of the medial FTJ and prominent tibial spines. Prominent TITP is a secondary sign of osteoarthritis. At histologic examination, increasing size of TITPs represents osteophytosis or enthesopathy of the TITP.

Adolescent↗
PubMed1996

Does altered biomechanics cause marrow edema?

PURPOSE: To determine if altered weight bearing causes the appearance of marrow edema on magnetic resonance (MR) images. MATERIALS AND METHODS: Twelve volunteers underwent MR imaging with a short inversion time inversion-recovery (STIR) sequence at 1.5 T. The hips, knees, ankles, and feet were evaluated before and 2 weeks after altered weight bearing achieved with overpronation of one foot. Three volunteers underwent imaging a third time, 2 weeks after overpronation was stopped. Two observers assessed the images for evidence of marrow edema. RESULTS: Changes were seen on images in 11 volunteers; the overpronated side only was affected in 10. Most changes occurred in the foot followed by the tibia and the femur. Most changes were a diffuse increase in marrow edema. In two volunteers, the changes resembled those of stress fractures. CONCLUSION: Altered weight bearing should be added to the list of causes of increased medullary signal intensity (ie, marrow edema) on MR images.

Adult↗