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Biomedical subjects

P R Miller

Publications and source records attributed to P R Miller.

At least 19 recordsLinked to original sources
PubMed1996

A false-positive diagnosis of Turner syndrome by amniocentesis.

A 45,X karyotype was observed in all cells examined from an amniotic fluid sample taken at 16 weeks' gestation from a 37-year-old patient referred because of her age. Following termination of the pregnancy, all cells examined from fetal tissues (cardiac blood, skin, and muscle) showed a 46,XX karyotype. The most likely explanation for the discordant results is thought to be a dizygotic twin pregnancy with a normal fetus and an empty sac, the latter being sampled at amniocentesis resulting in a 45,X karyotype.

Adult↗
PubMed1996

Color perception with test and adapting lights perceived in different depth planes.

Adapting to a chromatic light can alter the color appearance of other lights in view. The chromatic adapting effect is measured here with the test and adapting field perceived in the same depth plane, or perceived in different depth planes (using stereo disparity). The measurements show only a weak, though consistent, shift in the appearance of the test when adapting field and test are perceived in different depth planes, compared to when they are in the same plane. Adding complexity to the adapting stimulus, in the form of a second chromatic light surrounding the background, alters the appearance of the test but shows no dependence on the depth relations. Overall, there is only a small difference in chromatic adaptation caused by introducing a three-dimensional representation of these stimuli.

Adaptation, Physiological↗
PubMed1995

Synovial thickening detected by MR imaging in osteoarthritis of the knee confirmed by biopsy as synovitis.

Previous studies have established the value of magnetic resonance imaging (MRI) in detecting articular changes characteristic of osteoarthritis (OA) of the knee. We have observed some MRI features in OA of the knee presumably indicating synovial thickening. To determine whether these MR features represent chronic synovial inflammation, we studied the knees of nine patients at the mild end of the spectrum of OA of relatively short duration (89%: < or = 4 yr), who were selected because MRI showed anatomical abnormalities compatible with synovial thickening. The painful knee was examined using conventional and weight-bearing radiographs, MRI, and arthroscopy. MR images suggestive of synovial thickening typically appeared in or near the intercondylar region of the knee, in the infrapatellar fat pad, or in the posterior joint margin. The site of an arthroscopic biopsy of the synovial membrane was guided by MRI to the area thought to represent synovial thickening for each patient knee. Pathological examination of these synovial membrane biopsies showed a mild chronic synovitis, and thus a correspondence with the synovial thickening detected by MRI. Our results suggest that MRI can be used to evaluate the extent of synovitis, observed as synovial thickening, in patients with early OA of the knee.

Arthroscopy↗
PubMed1995

Clubfoot deformity in Down's syndrome.

The association of Down's syndrome (trisomy 21) with clubfeet has not previously been elaborated. Eight patients with a total of 15 clubfeet were identified for review. Five of these had trisomy 21 noted by chromosomal analysis, and 1 had a mosaic pattern. Two patients did not have chromosomal documentation, but had characteristic features of Down's syndrome. Interestingly, 2 patients had evidence of arthrogryposis as well as Down's syndrome. Four of the 8 patients had other orthopedic anomalies, including scoliosis, atlantoaxial instability, brachydactyly, and coxa valga. All 8 patients had an initial period of casting prior to any surgical intervention. Fourteen of the 15 feet required surgical intervention to afford correction of the deformity. The 6 feet with relatively long-term follow up (average: 5 years) showed that there was 1 excellent, 4 good, and 1 fair result using the criteria of Turco. It appears that, even though Down's syndrome is usually characterized by ligamentous laxity, when clubfeet are associated with this syndrome they are often resistant to nonoperative treatment, and surgical treatment seems to produce an acceptable result.

Casts, Surgical↗
PubMed1994

MR features of osteoarthritis of the knee.

A group of patients with idiopathic osteoarthritis (OA) of the knee was surveyed using weight-bearing radiographs and MR imaging to compare the relative value of these methods in disease evaluation. Fifty-two patients with a clinical and radiological diagnosis of OA of the knee of relatively short duration (87%: < or = 4 yr) were compared to a reference group of 40 age- and sex-comparable subjects with no knee symptoms. All patients had a complete history, physical examination, standard anterior-posterior and lateral weight-bearing radiographs, T1-weighted, and FLASH MR images in both knees. The prevalence of MRI abnormalities was significantly greater in patients with OA of the knee in all radiographic grades (Kellgren and Lawrence) compared to the reference subjects. Significant differences were encountered for synovial thickening (OA, 73%; reference, 0%), synovial fluid (60%; 7%), meniscal degeneration (52%; 7%), osteophytes (67%; 12%), and subchondral bone involvement (65%; 7%), even in the patients at the mild end of the osteoarthritic spectrum, indicating the exquisite sensitivity of MRI compared with weight-bearing radiographs.

Adult↗
PubMed1994

Factors affecting articular cartilage thickness in osteoarthritis and aging.

OBJECTIVE: To test the hypothesis that both aging and osteoarthritis (OA) contribute to the variance of human articular cartilage thickness of the knee and whether these contributions occur predominantly at weight bearing cartilage sites. METHODS: Thin, sagittal magnetic resonance images (MRI) of both knees were examined in 52 patients with idiopathic OA of the knee of short duration (87%: < or = 4 years) and 40 reference subjects of comparable age and sex distribution. Articular cartilage thickness was measured at the weight bearing and nonweight bearing femoral condylar, tibial plateau, and posterior patellar sites. Multiple regression analyses were performed to examine the influence of OA, age, sex, obesity (body mass index), and bone size on cartilage thickness. RESULTS: Age accounted for a significant linear decrease (p < 0.001) in both lateral and medial weight bearing femoral cartilage thickness of both knees, but failed to account for any significant variance in thickness at other cartilage sites. OA accounted for a significant decrease (p < 0.02) in the thickness of the femoral articular cartilage in the medial and lateral right knee compartments and in the lateral left knee compartment, but not in the medial left knee compartment. Significant cartilage thinning could be detected by MRI in patients with OA, even when the joint space was normal radiographically. CONCLUSION: The asymmetric decrease in the left knee may reflect the effect of mechanical factors. Our data show that articular cartilage thickness decreases at the femoral weight bearing sites both with age and as a consequence of OA and that these contributions can be distinguished from one another.

Adult↗
PubMed1993

MRI of the knee: practical imaging techniques and abnormalities.

Magnetic resonance imaging of the structures of the knee joint can be performed rapidly with current commercially available instruments. This article outlines methods for obtaining comprehensive clinical imaging studies within a 30-min time frame and reviews the MR appearance of knee joint disorders.

Contrast Media↗
PubMed1992

Radiation resistance in a doxorubicin-resistant human fibrosarcoma cell line.

In clinical practice, cancers refractory to chemotherapy can appear relatively radioresistant. Recent work in multidrug-resistant cell lines has yielded conflicting results concerning the relationship between drug resistance and radiation resistance. The current study examines the radiation response of a human fibrosarcoma (HT1080) and a doxorubicin-resistant subline (HT1080/DR4). Using soft-agar colony formation after graded doses of x-rays as an endpoint, HT1080/DR4 had an increased D0 (D0 = 2.1 Gy) and a broader initial shoulder (n = 2.7, Dq = 2.1 Gy) than the parental HT1080 line (D0 = 0.7, Gy, n = 1.2, Dq = 0.3 Gy), suggesting that HT1080/DR4 has an increased capacity to repair radiation-induced DNA damage. This possibility was tested by comparing the cell lines' ability to accumulate sublethal damage. In split-dose recovery experiments, HT1080/DR4 demonstrated increased ability to repair sublethal radiation damage following fractionated irradiation, compared with the HT1080 parental line. The mechanism for this radiation resistance is not clear, but a variety of cellular alterations seen in drug-resistant cell lines are discussed with reference to areas of further study.

Cell Cycle↗
PubMed1992

Effects of v-src oncogene activation on radiation sensitivity in drug-sensitive and in multidrug-resistant rat fibroblasts.

Recent work has implicated the activated ras oncogene, whose gene product is a G-protein located in the plasma membrane, as well as the activated raf oncogene, whose gene product is a membrane-associated protein kinase, in contributing to radioresistance. Another transforming oncogene whose gene product is localized to the plasma membrane is v-src. We have examined a rat fibroblast line (RAT-1) infected with an avian sarcoma virus carrying a temperature-sensitive mutation in the v-src tyrosine kinase domain (LA-24). At 40 degrees C, LA-24 cells have a flat morphology and grow as a contact-inhibited monolayer, while at 35 degrees C, LA-24 cells have a transformed morphology, lose contact inhibition, grow in soft agar, and exhibit 3.5-fold higher tyrosine kinase activity. The parental RAT-1 line, not infected by the virus, grows at both temperatures as a contact-inhibited monolayer. This well-characterized system represents a good model for examining the effect of v-src transformation on radiosensitivity. RAT-1 and LA-24 cells grown at 35 and 40 degrees C were irradiated with graded doses of radiation, and clonogenic survival was assayed. For LA-24 cells grown at 35 and 40 degrees C, and for RAT-1 cells grown at 35 and 40 degrees C, calculated D0, n, alpha, and beta values did not differ significantly. To determine whether there might be differences in radiation damage repair capacity too subtle to detect by comparing radiation survival curves, sublethal damage repair capacity was assessed. There was no difference in sublethal damage repair capacity for LA-24 cells grown at 35 or 40 degrees C. Other studies have associated multidrug resistance with radioresistance. We have examined the radiation sensitivity of two colchicine-resistant LA-24 clones with four- to fivefold amplification of the P-glycoprotein gene, which are four-to fivefold more resistant to colchicine than the parental LA-24 line. In these multidrug-resistant clones, v-src activation does appear to increase radiation resistance. This did not appear to be due to alteration in cell cycle kinetics. We conclude that oncogene activation, or even protein kinase activity per se, does not necessarily lead to radiation resistance. Rather, radiation resistance following oncogene activation depends upon the oncogene and cell line studied, and perhaps upon specific protein phosphorylation.

Animals↗
PubMed1991

Medial dislocation of the patella.

Medial dislocation of the patella is a previously unreported entity. This disorder can be disabling to the patient and may require a hospital visit for reduction. Three cases are presented in this article in which computed tomography demonstrated the dislocation. All three patients had undergone a lateral retinacular release to the involved knee for treatment of chronic knee pain or recurrent lateral patellar subluxation.

Adult↗
PubMed1987

Acute ureteral obstruction as a complication of suprapubic catheterization.

Suprapubic cystostomy catheters are an important tool for the management of patients who require urinary drainage. Although complications occur after the procedure, they are usually minor. A case of acute obstruction at the ureterovesical junction caused by a suprapubic cystostomy catheter tip is presented.

Acute Disease↗
PubMed1987

Detection and quantification of laryngotracheopulmonary aspiration with scintigraphy.

Aspiration is analyzed by a new scintigraphic technique and standard videofluoroscopy in 78 patients with head and neck pathology and neurologic disorders. When both methods are compared to clinical aspiration and a positive x-ray film of pneumonia, they appear to complement each other and provide a very accurate evaluation. Scintigraphy is a more sensitive method for detecting aspiration below the vocal cords and also provides for flow dynamics and a method of quantifying the amount of aspirated material. Videofluoroscopy shows more clearly the mechanism of the swallowing disorder and how the bolus enters the tracheobronchial tree. Studies in patients following head and neck surgery demonstrate a high incidence of dysphagia, aspiration, and pneumonia.

Deglutition↗
PubMed1984

Celestin tube use: radiographic manifestations of associated complications.

Celestin intubation of the esophagus is occasionally employed in the palliation of unresectable esophageal carcinoma and in the obturation of malignant tracheoesophageal fistulas. Fourteen of 192 patients with carcinomas of the esophagus had Celestin tubes inserted at our institution between October 1977 and October 1982. Although tube insertion carries a low operative risk, there is significant subsequent morbidity associated with its use. Complications were identified radiographically in 11 of the 14 patients. Gastroesophageal reflux with aspiration pneumonia, tube obstruction, and tube migration were demonstrated most often. When Celestin tube use is deemed appropriate, the clinician and radiologist should be aware of the possible complications.

Adult↗
PubMed1984

Computed tomography and lymphangiography in chyluria.

Computed tomographic findings following lymphangiography are presented in a patient with chyluria. The etiologies of chyluria and its pathogenesis are briefly discussed. Computed tomography in combination with lymphangiography may be indicated to establish or exclude associated retroperitoneal masses or lymph node enlargement and to better localize abnormal retroperitoneal and pelvic lymphatic vessels.

Chyle↗