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Biomedical subjects

D G Sanders

Publications and source records attributed to D G Sanders.

At least 19 recordsLinked to original sources
PubMed1999

Kinematic analysis of left ventricular deformation in myocardial infarction using magnetic resonance cardiac tagging.

The Magnetic Resonance (MR) tagging technique provides detailed information about 2D motion in the plane of observation. Interpretation of this information as a reflection of the 3D motion of the entire cardiac wall is a major problem. In finite element models of the mechanics of the infarcted heart, an infarcted region causes motional asymmetry, extending far beyond the infarct boundary. Here we present a method to quantify such asymmetry in amplitude and orientation. For this purpose images of a short-axis cross-section of the ejecting left ventricle were acquired from 9 healthy volunteers and 5 patients with myocardial infarction. MR-tags were applied in a 5 mm grid at end-diastole. The tags were tracked by video-image analysis. Tag motion was fitted to a kinematic model of cardiac motion. For the volunteers and the patients the center of the cavity displaced by about the same amount (p = 0.11) during the ejection phase: 3.8 +/- 1.4 and 3.0 +/- 0.9 mm (mean +/- sd), respectively. Cross-sectional rotation and the decrease in cross-sectional area of the cavity were both greater in the volunteers than in the patients: 6.4 +/- 1.5 vs. 3.0 +/- 0.8 degrees (p < 0.001), and 945 +/- 71 vs. 700 +/- 176 mm2 (p = 0.02), respectively. In the patients, asymmetry of wall motion, as expressed by a sine wave dependency of contraction around the circumference, was significantly enlarged (p = 0.02). The proposed method of kinematic analysis can be used to assess cardiac deformation in humans. We expect that by analyzing images of more cross-sections simultaneously, the 3D location and the degree of infarction can be assessed efficiently.

Biomechanical Phenomena↗
PubMed1998

Is the chest radiograph a reliable tool in the assessment of tumor response after radiotherapy in nonsmall cell lung carcinoma?

BACKGROUND: The purpose of this study was to evaluate whether the chest radiograph is a reliable tool to assess response to radiotherapy. MATERIALS AND METHODS: Pre- and post-treatment chest radiographs and computed tomographs (CT) of 63 patients with nonsmall cell lung cancer (NSCLC) treated by radiotherapy were reviewed by four observers with regard to suitability for tumor measurement, and response. Suitability for tumor measurement was expressed as the number of measurable diameters. In addition, the consequences to clinical outcome were studied by survival analysis. RESULTS: The CT turned out to be more suited for tumor measurement before as well as after radiotherapy, resulting in an increase of the number of measurable cases. The number of measurable cases with CT was 52 (83%) as compared to 28 (44%) with chest radiography. Especially in case of centrally localized tumors, the presence of an atelectasis, or squamous cell carcinoma, CT contributed to a higher rate of measurable cases. The interobserver agreement with regard to response using chest radiograph was good (mean kappa = 0.74). In 25 of 28 cases (89%) measurable with CT as well as with chest radiograph, response was equally classified. When CT was used, the median survival of the responders was 14.2 months as compared to 6.8 months of the nonresponders. When chest radiograph was used, the median survival of these groups was 12.0 and 6.6 months respectively, which was not significantly different when response was assessed by CT. CONCLUSION: We conclude that CT is more suited for tumor measurement because more measurable lesions can be found and more evaluable lesions on chest radiograph become measurable on CT. The chest radiograph does have a valuable role to play in those lesions that are measurable because of the good interobserver agreement with regard to the response classification, the high overall agreement between CT and chest radiograph in case of measurable cases, and the lack of important differences with regard to survival.

Adult↗
PubMed1997

Relation between torsion and cross-sectional area change in the human left ventricle.

During the ejection phase, motion of the left ventricular (LV) wall is such that all myocardial fibers shorten to the same extent. In a mathematical model of LV mechanisms it was found that this condition could be satisfied only if torsion around the long axis followed a unique function of the ratio of cavity volume to wall volume. When fiber shortening becomes non-uniform due to cardiac pathology, this pathology may be reflected in aberration of the torsional motion pattern. In the present study we investigated whether the predicted regular motion pattern could be found in nine healthy volunteers, using Magnetic Resonance Tagging. In two parallel short-axis cross-sections, displacement, rotation, and area ejection were derived from the motion of tags, attached non-invasively to the myocardium. Information from both sections was combined to determine area ejection, quantified as the change in the logarithm of the ratio of cavity area to wall area, and torsion, represented by the shear angle on the epicardium. Linear regression was applied to torsion as a function of area ejection. The slope thus found (-0.173 +/- 0.024 rad, mean +/- S.D.) was similar to the slope as predicted by the model of LV mechanics (-0.194 +/- 0.026 rad). In conclusion, the relation between area ejection and torsion could be assessed noninvasively in humans. In healthy volunteers, the relation was close to what was predicted by a mathematical model of LV mechanics, and also close to what was found earlier in experiments on animals.

Algorithms↗
PubMed1997

The effect of a single rectal dose of cisapride on delayed gastric emptying.

BACKGROUND: Cisapride has an established prokinetic effect in patients with delayed gastric emptying. However, rectal administration of the drug might be preferred in patients with either dysphagia or nausea due to gastroparesis. AIM: To determine the effect of a single rectal dose of cisapride 60 mg on gastric emptying in patients with delayed gastric emptying. METHODS: Thirty-two patients (16 males, 16 females) with demonstrated delayed gastric emptying received a single dose of two suppositories containing either cisapride (2 x 30 mg) or placebo, according to a double-blind randomized crossover design. Three hours after administration of the suppositories, the patients received a radio-labelled test meal and radio-opaque markers for measurement of gastric emptying. RESULTS: The mean t1/2 after cisapride administration (76 min, 95% CI: 68-95) was significantly shorter (P = 0.005: n = 28, per-protocol analysis) than after placebo administration (104 min, 81-126). Four hours after ingestion of the meal significantly fewer radio-opaque markers remained in the stomach after cisapride than after placebo administration (P < 0.05). Mild to moderate adverse events, mainly involving the gastrointestinal tract, were reported in 10 patients (31%) after cisapride treatment and in four patients (13%) after placebo (N.S.: n = 32). CONCLUSION: A single suppository dose of cisapride 60 mg significantly accelerates gastric emptying of the solid phase of a meal and of radio-opaque markers in patients with previously demonstrated delayed gastric emptying.

Administration, Rectal↗
PubMed1994

MRI findings in Caffey's disease.

A patient with infantile cortical hyperostosis (ICH) is presented. Common features in all reported patients include: onset in the early part of the 1st year, tender swellings in more than one site and multiple scattered hyperostoses shown by radiography, but no previous study has determined the cause or origin of ICH. Biopsy of bony lesions only reveals hyperplasia of the lamellar cortical bone, without inflammation or subperiosteal haemorrhage. Although MRI resulted in excellent images for differentiation between bony and soft tissue structures and for evaluation of the extent of soft tissue involvement, it had no additional value in the management of the patient. Only in questionable cases can MRI provide additional information about the presence of a subperiosteal haemorrhage. Radiographic examination, in addition to clinical history and physical examination, is considered sufficient with regard to differential diagnosis and follow up of ICH.

Bone and Bones↗
PubMed1993

Ocular findings in cerebro-ocular-myopathy syndrome (COMS). A possible role of growth factors?

The clinical and histopathological findings are described in a case of cerebral and ocular abnormalities associated with (congenital) muscular dystrophy. Histopathological examination of the eyes revealed a fetal configuration of the anterior chamber angle, elongated ciliary processes, cataract, persistence of primary hyperplastic vitreous and total retinal detachment with retinal dysplasia. The similarity of ocular findings in Walker-Warburg syndrome, muscle-eye-brain disease and Fukuyama's congenital muscular dystrophy, and the role of growth factors as a possible unifying (foetal) cause are discussed. This case has been presented at the meeting of the EOPS Verhoeff Society, Nürnberg 1991.

Abnormalities, Multiple↗
PubMed1991

Serial immunocytologic analysis of blood for tumor cells in two patients with neuroblastoma.

Tumor surveillance tests are used to determine whether malignant cells are responsive or resistant to therapeutic regimens. For patients with neuroblastoma, conventional methods of surveillance are not sensitive enough. Because tumor cells are shed into the circulation, immunocytologic analysis of blood may function as a sensitive monitoring system. In this study, five blood samples were obtained from two patients with disseminated neuroblastoma at diagnosis and during therapy. These samples were analyzed with monoclonal antibodies and immunoperoxidase staining to determine whether circulating neuroblasts were present. In both patients, the presence or absence of circulating neuroblasts yielded information that was more sensitive than that from conventional tests. The authors conclude that immunocytologic analysis of blood should be included with conventional monitoring methods for surveillance of patients with disseminated neuroblastoma.

Antibodies, Monoclonal↗
PubMed1991

Pattern electroretinography in senile macular degeneration.

The value of pattern electroretinography (PERG) for the detection and differentiation of senile macular degeneration (SMD) was assessed. A group of patients with atrophic SMD and a group with exudative SMD were compared with an age-matched reference group. Differences were only found in visual acuity and in the amplitude of the negative peak N95. No statistical differences between the atrophic and exudative groups were found. Conclusions may be drawn from these results with regard to the use of PERG in senile macular degeneration.

Aging↗
PubMed1990

Contamination of peripheral blood stem cell harvests by circulating neuroblastoma cells.

Peripheral blood stem cells (PBSC) are being used as one alternative to autologous marrow rescue for patients with neuroblastoma and other solid malignancies. Some physicians prefer use of PBSC because less risk of tumor contamination is believed to exist. This hypothesis was evaluated by immunocytologic analysis of blood samples and concurrently drawn bone marrow (BM) samples and of PBSC harvests obtained from 31 patients with disseminated neuroblastoma. We found circulating neoplastic cells in 75% of specimens analyzed at diagnosis, in 36% during therapy, and in 14% of PBSC harvests. Tumor cells in blood obtained during therapy did not appear until 3 months after the time of diagnosis. Clearance of circulating neuroblastoma cells was documented after two courses of induction chemotherapy. Six of 13 patients with minimal or no BM disease had positive blood specimens. We conclude that substantial risk of tumor contamination of PB harvests exists and recommend that induction chemotherapy be administered before hematopoietic progenitor cells are collected from blood.

Adolescent↗
PubMed1990

Detection of neuroblastoma cells in blood.

Tumor surveillance tests are used to detect relapse and to guide the clinician in making therapeutic changes. Identification of relapse early in the course of disease may improve long-term survival. For patients with neuroblastoma, current conventional surveillance methods include radiologic testing, bone marrow analysis, physical examination, and measurement of urinary catecholamine metabolites. Immunocytologic analysis of blood for the detection of circulating tumor cells is a highly specific and sensitive method, which may prove useful in monitoring patients with neuroblastoma. In our study, circulating tumor cells were detected in seven of 10 patients with known disseminated disease at diagnosis and in six of 13 patients during therapy. In some patients, as few as two tumor cells were identified among 100,000 normal hematopoietic cells. The presence or absence of circulating neuroblasts in the 13 patients evaluated during therapy was significantly correlated with tumor relapse (P = .002). We conclude that immunocytologic analysis of blood is a sensitive method for the detection of circulating neuroblasts. We recommend that this technique be used in conjunction with other conventional methods for improved tumor detection and subsequent monitoring of neuroblastoma patients.

Antibodies, Monoclonal↗
PubMed1988

Antiarrhythmic actions of left stellectomy in digitalis-mediated malignant ventricular arrhythmias in the postinfarcted canine heart.

Recently, this laboratory has demonstrated an enhanced susceptibility toward the development of ischemia-related lethal ventricular arrhythmias in the presence of therapeutic serum concentrations of digoxin in conscious dogs after myocardial infarction. The present study was performed to assess the effect of the interruption of cardiac sympathetic influences, via subacute left stellate ganglionectomy (LSGX), on digitalis-mediated ischemic ventricular arrhythmias. Commencing 4-5 days after anterior myocardial infarction, 11 dogs with LSGX and 14 sham controls were administered digoxin (0.0125 mg/kg/day i.v.) for 5-7 consecutive days. At baseline testing, programmed ventricular stimulation failed to initiate ventricular tachycardia in any postinfarction dog entered into this evaluation. After treatment, 11/11 digoxin + LSGX (1.33 +/- 0.10 ng/ml serum digoxin) and 14/14 digoxin-treated sham (1.23 +/- 0.14 ng/ml serum digoxin) dogs remained nonresponsive to programmed stimulation testing. The incidence of arrhythmic mortality in response to subsequent ischemia at a site remote from the infarcted anterior region was greater in the digoxin-treated sham group (1.22 +/- 0.21 ng/ml serum digoxin) than in the digoxin + LSGX group (1.33 +/- 0.10 ng/ml serum digoxin); mortality was 6/10 (60%) digoxin sham vs. 1/10 (10%) digoxin + LSGX, p less than 0.005. The underlying anterior myocardial infarct sizes (% of left ventricle: 6.8 +/- 2.3 vs. 6.6 +/- 1.1) did not differ between the digoxin sham and digoxin + LSGX groups. However, the digoxin sham controls developed larger posterolateral myocardial infarctions than did the digoxin + LSGX animals (% of left ventricle: 27.4 +/- 3.0 vs. 16.7 +/- 2.7, p less than 0.05). Norepinephrine concentrations in posterolateral through posteroseptal ventricular sections were not altered by LSGX in a separate group of digoxin-treated postinfarct dogs. The results suggest that left stellate ganglionectomy may reduce the incidence of digitalis-mediated malignant ventricular arrhythmias during ischemia, possibly due to a reduction in the severity of ischemic injury.

Animals↗
PubMed1975

Lithium in treatment failures.

Thirty-five patients with chronic and incapacitating mental illness who had not responded to the usual pharmacological and interactional therapies were treated with lithium. None of these patients appeared to be suffering from manic-depressive illness. If a trial of lithium resulted in unexpected improvement, lithium's contribution was assessed by double blind substitution of a placebo followed by lithium in an A-B-A-B design in which the patient served as his own control. Five patients (14 per cent) improved dramatically; in retrospect, four of these five patients suffered from nonremitting forms of manic-depressive illness, and the fifth patient suffered from a severe obsessive compulsive neurosis. Six other chronically hospitalized patients improved to the point of unexpected discharge. A trial of lithium therapy is recommended for the "backward" or intractable patient.

Adult↗