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Biomedical subjects

D Wertheim

Publications and source records attributed to D Wertheim.

15 recordsLinked to original sources
PubMed2001

Clinical and computerized assessment of mandibular asymmetry.

The aim of this study was to investigate assessment of mandibular asymmetry by clinicians and to evaluate a new computerized system. Eight experienced clinicians (four maxillofacial surgeons and four orthodontists) assessed 12 standardized facial photographs of patients selected to provide a range, from normality to marked mandibular asymmetry. Photographs were taken under standardized conditions; analysis of photographs repeated after one month showed close agreement. The computerized system used four different methods for quantifying asymmetry based on right/left differences in perimeter, area, compactness, and centre of area ratios. Good agreement (kappa = 0.77) was achieved by the clinicians in assessing the likelihood of treatment need; however, when assessing an 'acceptable' level of asymmetry, agreement was moderate (kappa = 0.46). Differences in perimeter ratios did not compare well with clinical assessment, but those for both area and compactness showed 100 per cent sensitivity and specificity to clinical assessment at ratio differences of 0.05 and 0.03 (deviation from 1), respectively. A centre of area difference ratio greater than 1 showed 75 per cent sensitivity and 85 per cent specificity to clinical assessment. These parameters could prove useful in quantifying change in asymmetries brought about by growth, treatment, or any subsequent relapse.

Adolescent↗
PubMed1999

Measurement of forces associated with compression therapy.

Compression therapy is the principal treatment for leg ulcers associated with venous disease. The efficacy of compression therapy can be variable, which may in part be owing to the degree of compression applied. However, if the mechanism of action of this treatment could be better understood, it might be possible to improve its efficacy. It is not clear whether assessment of the degree of compression should be made under static or dynamic conditions, or both. A review of methods used previously suggests the need for a new method of assessment allowing continuous monitoring, even during movement. A system for continuous static and dynamic measurements of compression is described. Using an air chamber and manometer to test the system, agreement within +/- 3 mmHg is observed. The system is applied to investigate changes in forces, expressed as pressure, under bandages and compression stockings. Application of five bandage systems by experienced nurses to a volunteer shows a marked variation in applied pressure. During short periods of walking, rapid changes in pressure under compression stockings are observed, including some transients of less than 0.25 s. The method is simple to apply and may help to understand further the mechanism of action of compression therapy.

Bandages↗
PubMed1999

Interactive image processing system for assessment of cell movement.

The study of cancer cell motility is considered to be important in understanding cancer metastasis. The movement behaviour of cells within clustered cell colonies is of particular interest. Changes in cell movement, area and velocity can be an indicator of cell spreading. The aim of the study is to develop and apply a computerised interactive image processing system to quantify the movement of cells within cell clusters. A semi-automatic boundary description method based on two-dimensional rendering is devised. The system is later combined with image-processing methods that facilitate the relocation of the cell boundary over time; this forms a new approach to assessing cell movement. These methods are incorporated into a software system, enabling an interactive procedure to define and monitor the movement of single cells in cell clusters from digitised microscope images. Validation of the method shows a maximum error of 10% in defining the area through a cubic spline interpolation. The system is applied to analyse the movement and area of HT115 human colon cancer cells. The system provides tools for the analysis of movement, area and velocity of single cells in cancer cell colonies and may thus be of value in further understanding cancer cell motility.

Cell Movement↗
PubMed1999

Movement-related variation in forces under compression stockings.

OBJECTIVES: Compression therapy is widely used in the treatment of venous leg ulcers, but the efficacy of this treatment is variable. Assessment of variation in compression forces associated with movement may help to elucidate the mechanism of action of compression therapy. The aim of this study was to develop and apply a system to investigate forces under compression stockings during movement. METHOD: Three sensors were placed on the medial aspect of the left leg on six healthy volunteers to monitor forces under class 2 (Continental European classification) compression stockings. Data were recorded during dorsiflexion and plantar flexion of the left foot and also during short periods of walking. RESULTS: Changes in pressure were observed, associated with dorsiflexion and plantar flexion of the foot. These changes were dependent on sensor position. Changes in pressure during walking were also position-dependent and of variable duration. CONCLUSIONS: The system enables forces associated with compression therapy to be examined during movement and may thus be of value in further understanding its mechanism of action. Foot movement can be associated with clear changes in pressure under compression stockings and rapid changes in pressure may occur during walking.

Adult↗
PubMed1994

Reversible changes in cerebral activity associated with acidosis in preterm neonates.

Computerized online EEG monitoring in ventilated preterm infants less than 32 weeks' gestation enabled evaluation of the effect of acidosis on cerebral function. All episodes of acidosis were found to be associated with changes in the levels of cerebral activity. In 21 of the 32 episodes, EEG activity returned to pre-acidosis levels after therapeutic intervention. The duration of EEG abnormality was related to the severity of acidosis. However, the time to recovery of the EEG after therapeutic procedures was not related to duration of the EEG change.

Acidosis↗
PubMed1994

Prognostic value of continuous electroencephalographic recording in full term infants with hypoxic ischaemic encephalopathy.

The prognostic value of early neonatal continuous electroencephalographic recordings in hypoxic ischaemic encephalopathy was evaluated. Thirty seven full term infants with hypoxic ischaemic encephalopathy were studied. The electroencephalogram (EEG) was recorded using four or eight channel Oxford Medilog recorders and was started as soon as possible after birth. The recordings were initially visually analysed and divided into four categories: three in relation to the grade of discontinuity of the background activity (continuous, discontinuous, and maximum depression) and an additional fourth category to include status epilepticus. The EEGs with discontinuous activity were then analysed by computer to obtain a more objective assessment of discontinuity. The results were related to neurological outcome. Continuous background activity was associated with a normal outcome in all but the three infants who had continuous, but asymmetrical EEGs and who developed contralateral hemiplegia. In the eight infants with discontinuous activity, the outcome appeared to be related to the grade of continuity and the presence of clear convulsions on the EEG. The 10 infants with maximum depression and status epilepticus had severe impairment. These preliminary results suggest that continuous recording of EEGs could be used routinely in term infants with hypoxic ischaemic encephalopathy. Computer analysis can improve the value of this technique, allowing the identification of infants who might benefit from early therapeutic intervention.

Brain Damage, Chronic↗
PubMed1993

MELAS point mutation with unusual clinical presentation.

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is a multisystemic mitochondrial disorder (Pavlakis et al. Advances in Contemporary Neurology. Philadelphia: Davis, 1988: 95-133) and most patients with the typical MELAS phenotype have a point mutation in mitochondrial DNA, an A to G transition at nucleotide 3243 (Goto et al. Nature 1990; 348; 651-653; Koboyashi et al. Biochem Biophys Res Commun 1990; 173: 816-822; Ciafaloni et al. Ann Neurol 1992; 31: 391-398). A 9-yr-old boy presenting with chronic asthma and depression was found to have abnormal mitochondria, partial defects of respiratory chain enzymes, and the MELAS point mutation.

Acid-Base Imbalance↗
PubMed1992

The effect of pethidine on the neonatal EEG.

Thirty-two preterm infants were monitored with an on-line cotside EEG system for periods of up to nine days. Changes in the normal pattern of discontinuity of the EEG were seen in association with pethidine administration. The duration of the EEG suppression after pethidine administration was greatest after the first dose and progressively less with subsequent doses. It was not related to the gestational maturity or postnatal age at which the dose was given. This system of EEG analysis allowed recognition of this previously undescribed effect of pethidine on the neonatal EEG, and should have application to monitoring the effects of brain function of other drugs in routine neonatal practice.

Brain↗
PubMed1991

Cerebral blood flow velocity changes after rapid administration of surfactant.

A computer linked Doppler system was used to make continuous measurements of cerebral blood flow velocity (CBFV) from the middle cerebral artery, mean arterial blood pressure (MAP) from the umbilical artery, and heart rate before, during, and for 20 minutes after the endotracheal administration of 200 mg/kg of porcine surfactant in 10 preterm infants with respiratory distress syndrome. Within two minutes of surfactant administration, there was a median fall of 6 mm Hg (15%) fall in MAP and 36% in CBFV. There was a change in the Doppler spectra with almost complete loss of diastolic velocities. A rapid reduction in pulmonary vascular resistance with consequent left to right ductal shunting is one possible cause. These acute changes in MAP and CBFV after bolus surfactant administration may increase the risk of intraventricular haemorrhage.

Blood Flow Velocity↗
PubMedDate not supplied

A system for computer analysis of cancer cell movement.

BACKGROUND: Motility of cancer cells is a principal cellular parameter, essentially required in the invasion and formation of distant metastasis in human cancer. Measures to stimulate or inhibit motility of cancer cells may play an important part in the understanding of metastasis biology. The aim of this study was to develop a computer system to analyse and evaluate the movement of cells. METHOD: Software was developed which enabled cell boundary definition by specifying salient points around the cell. The position of the centre of area was calculated. Six human cancer cells treated with a motogen and cells without added motogen were analysed by the system. RESULTS: We observed higher velocities and greater variation in area and velocity of the cells treated with HGF/SF motogen compared with control cells. CONCLUSION: The system enables rapid analysis of cell area, velocity and movement, and may thus be of value in further understanding cell motility.

Cell Movement↗