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Biomedical subjects

M Dick

Publications and source records attributed to M Dick.

At least 19 recordsLinked to original sources
PubMed2006

[Presbyopia treatment using a femtosecond laser].

Presbyopia is by far the most common refractive error worldwide, with no permanent therapeutic option available. All efforts to restore accommodation by the use of surgery have not led to a generally accepted therapy. However, there is evidence from an animal model that the use of a femtosecond (fs) laser might influence the modulus of elasticity in the lens. Fs-laser impulses can create intralenticular disruption in animal eyes as well as human cadaver lenses and improve elasticity. The concept of treating presbyopia with fs-laser requires a new, complex theory combining the optical and the mechanical aspects of accommodation in the eye. Diagnostic tools for measuring optical change in power and geometrical modification as the eye views from far to near are needed to obtain objective clinical data. A non-invasive treatment of presbyopia to restore accommodation might be possible in the future.

Accommodation, Ocular↗
PubMed2004

Pulmonary function abnormalities in children with sickle cell disease.

BACKGROUND: Adults with sickle cell disease (SCD) have restrictive lung function abnormalities which are thought to result from repeated lung damage caused by episodes of pulmonary vaso-occlusion; such episodes start in childhood. A study was therefore undertaken to determine whether children with SCD have restrictive lung function abnormalities and whether the severity of such abnormalities increases with age. METHODS: Sixty four children with SCD aged 5-16 years and 64 ethnic matched controls were recruited. Weight and sitting and standing height were measured, and lung function was assessed by measurement of lung volumes and forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF) before and after bronchodilator. RESULTS: Compared with the control subjects, the children with SCD had lower mean (SD) sitting height (69 (6.3) cm v 73 (7.7) cm; p=0.004), sitting:standing height ratio (0.50 (0.02) v 0.51 (0.01); p<0.0001), weight (33 (10.9) kg v 41 (14.9) kg; p=0.001), functional residual capacity measured by a helium gas dilution technique (1.2 (0.3) l v 1.3 (0.4) l; p=0.04), FEV1 (1.5 (0.5) l v 1.9 (0.7) l; p=0.0008), FVC (1.7 (0.6) l v 2.1 (0.8) l; p=0.001), and PEF (3.9 (1.3) l/s v 4.8 (1.5) l/s; p=0.0004). The effect of age on lung function differed significantly between the children with SCD and the controls for total lung capacity and vital capacity measured by plethysmography and functional residual capacity measured by helium gas dilution. CONCLUSION: Lung function differs significantly in children with SCD compared with ethnic matched controls of a similar age. Our results suggest that restrictive abnormalities may become more prominent with increasing age.

Adolescent↗
PubMed2003

Reversible symptomatic dilated cardiomyopathy in older children and young adolescents due to primary non-sinus supraventricular tachyarrhythmias.

Dilated cardiomyopathy (DCM) due to a primary supraventricular tachycardia not originating from the sinus node is not frequently seen in older children or adolescents. However, it is important to recognize this entity as a reversible cause of DCM to avoid costly and inappropriate treatments for these patients. We describe 7 patients who presented with DCM. Five were misdiagnosed as having "sinus" tachycardia secondary to an idiopathic DCM, and 2 were correctly diagnosed as having DCM secondary to an atrial tachycardia. All underwent electrophysiologic treatment of the tachycardia with remission of the DCM.

Adolescent↗
PubMed2003

Rapid antigen testing for the surveillance of influenza epidemics.

OBJECTIVE: To assess the use of a 'near patient' test for rapid antigen detection to obtain the more timely acquisition of data for the surveillance of influenza epidemics. METHODS: To the classical cell culture system used for the surveillance of influenza, a 'near patient' test was added. The cell culture method was applied for the detection of influenza virus in specimens sent to our laboratory. In contrast, the 'near patient' test was used directly by practitioners in their practices to screen patients for the presence of influenza virus antigen. RESULTS: The results for two seasons are presented. The 'near patient' test was able to detect a developing influenza epidemic with the same reliability as clinical consultation reports for influenza-like illness or the conventional culture method. However, the results obtained were available 9 days earlier on average, compared with cell culture. Because of this, results concerning the epidemics could be announced via the internet more rapidly. Although the 'near patient' test demonstrated a lower sensitivity than detection by conventional cell culture, the sensitivity was still sufficiently high to reveal the characteristics of the epidemics in the community. CONCLUSIONS: Rapid influenza testing is a reliable tool for influenza surveillance and, compared with traditional methods (virus detection on cell culture and monitoring of influenza-like illness), provides faster results. Although the 'near patient' test has limited sensitivity compared with cell culture, results were consistent over two seasons, and suggest that rapid testing should be part of a surveillance program.

Antigens, Viral↗
PubMed2002

Coping and health service utilisation in a UK study of paediatric sickle cell pain.

AIMS: To assess sickle cell pain and coping in children and to examine the relation between these factors and the utilisation of health services. METHODS: Cross sectional study involving 67 children with sickle cell disease attending three London hospitals. Interviews and questionnaires involved measures of pain, health service utilisation, and coping responses (measured with the Coping Strategies Questionnaire (CSQ), revised for children with sickle cell disease). Medical data on complications, haemoglobin (Hb) levels, and foetal haemoglobin (HbF) percentage were also collected. RESULTS: Pain accounted for about 24% of hospital service use, independent of age, sex, number of with sickle cell disease complications, and Hb levels. However, 42% of patients had not utilised hospital services in the past 12 months. Three higher order factors emerged from analysis of the CSQ (active coping, affective coping, passive adherence coping). Pain severity was predicted by passive adherence coping, while utilisation of hospital services was predicted by active coping. CONCLUSIONS: Sickle cell disease in children involves severe recurrent pain leading to hospitalisation in some cases. Psychological coping patterns are relevant to both pain experience, and the use of acute hospital services. It is likely that children would benefit from community based interventions that incorporate both medical and psychological assessments.

Adaptation, Psychological↗
PubMed2002

The importance of using ethnically appropriate reference ranges for growth assessment in sickle cell disease.

Height and weight were measured and body mass index (BMI) calculated in 56 sickle cell disease (SCD), 57 Caucasian (CC), and 63 African/Caribbean (AC) 3-9 year old children. The SCD children were taller, but had similar weight and BMI to the CC controls. The SCD group had lower weight and BMI than the AC controls. The AC controls were of greater height, weight, and BMI than CC controls. These data highlight the importance of using ethnically appropriate reference ranges.

Aging↗
PubMed2001

Inducibility of intra-atrial reentrant tachycardia after the first two stages of the Fontan sequence.

OBJECTIVES: We sought to examine the incidence and possible factors for inducible intra-atrial reentrant tachycardia (IART) in a group of patients after two stages of the Fontan sequence but before the operation. BACKGROUND: Intra-atrial reentrant tachycardia occurs in 10% to 40% of patients after the Fontan operation. No data are available regarding the potential for IART after the first two stages of the Fontan sequence but before the operation. METHODS: The IART induction protocol included programmed extrastimulation and rapid atrial pacing, with and without isoproterenol. RESULTS: The median age of the study group (n = 44, 27 males) was 1.7 years (range 1.2 to 5.2). Forty patients were in sinus rhythm. Twelve patients (27%) had inducible, sustained (>1 min) IART. Three patients (8%) had inducible, nonsustained IART. Bivariate analysis revealed that patients with sustained IART were significantly older at their second operation (median 0.54 vs. 0.40 years, p = 0.05). Multivariate logistic modeling revealed that older age (> or =0.55 years) at the second palliative operation (p = 0.04), older age (> or =1.95 years) at evaluation before the Fontan sequence (p = 0.04) and female gender (p = 0.03) were independently associated with sustained IART. A trend toward a greater frequency of sustained IART was seen in those patients with moderate or severe atrioventricular valve regurgitation (p = 0.07) and in those with resection of the atrial septum (p = 0.06). CONCLUSIONS: The rate of inducible, sustained IART in a group of patients before the Fontan operation is 27% and is associated with older age at the time of second-stage palliation, older age at pre-Fontan evaluation and female gender.

Adolescent↗
PubMed2001

The clinical course of multifocal atrial tachycardia in infants and children.

OBJECTIVES: This study outlines the clinical course, treatment and the late outcome of infants and children with multifocal atrial tachycardia (MAT). BACKGROUND: Multifocal atrial tachycardia is defined by three distinct P-waveforms, irregular P-P intervals, isoelectric baseline between P-waves and rapid rate on an electrocardiogram. Several smaller prior reports have described pediatric patients with MAT, but their long-term outcome has not been fully assessed. METHODS: The clinical records, echocardiograms and long-term follow-up of patients with MAT were reviewed and compared to previous reports of MAT. RESULTS: Fourteen boys and seven girls (median age 1.8 months) presented with MAT. At diagnosis, six patients had respiratory illness, of whom two were critical. Ten were asymptomatic. Seven patients had structural heart disease (SHD), one of whom died. Four of 15 patients (27%) with echocardiograms had diminished ventricular function. Ventricular rates were 111 to 253 beats/min (mean 181 beats/min). Median duration of the arrhythmia was 4.9 months (mean 6.7 months). Electrical cardioversion was attempted in 4 patients without success and 15 patients received antiarrhythmic medication. Seventeen patients were followed for a mean of 60 months. Four patients were lost to follow-up. There were no late arrhythmias. CONCLUSIONS: The majority of children with MAT are healthy infants under one year of age; a few may exhibit mild to life-threatening cardiorespiratory disease. Less often, MAT accompanies SHD. Mild ventricular dysfunction may be observed in the presence of MAT, but symptoms are few and resolution is generally complete. Response to antiarrhythmic agents is mixed, and cardioversion is of no avail. Finally, long-term cardiovascular and developmental outcome depends principally on underlying condition; for otherwise healthy children, it is excellent.

Child↗
PubMed2001

The G-algorithm for extraction of robust decision rules--children's postoperative intra-atrial arrhythmia case study.

Clinical medicine is facing a challenge of knowledge discovery from the growing volume of data. In this paper, a data mining algorithm (G-algorithm) is proposed for extraction of robust rules that can be used in clinical practice for better understanding and prevention of unwanted medical events. The G-algorithm is applied to the data set obtained for children born with a malformation of the heart (univentricular heart). As the result of the Fontan surgical procedure, designed to palliate the children, 10%-35% of patients postoperatively develop an arrhythmia known as the intra-atrial reentrant tachycardia. There is an obvious need to identify the children that may develop the tachycardia before the surgery is performed. Prior attempts to identify such children with statistical techniques have been unrewarding. The G-algorithm discussed in this paper shows that there exists an unambiguous relationship between measurable features and the tachycardia. The data set used in this study shows that, for 78.08% of infants, the occurrence of tachycardia can be accurately predicted. The authors' prior computational experience with diverse medical data sets indicates that the percentage of accurate predictions may become even higher if data on additional features is collected for a larger data set.

Algorithms↗
PubMed2000

Use of a single coil transvenous electrode with an abdominally placed implantable cardioverter defibrillator in children.

While transvenous defibrillator electrode placement avoiding a thoracotomy is preferable, electrode size, a large intercoil spacing, and the need for subclavicular device placement preclude this approach in most children. We investigated a single RV coil to an abdominally placed active can ICD device. Five children ages 8-16 years (weight 21-50 kg, mean 35 kg) underwent ICD placement. Placement of a single coil Medtronic model 6932 or 6943 electrode was performed via the left subclavian vein approach and the electrode positioned in the RV apex with the coil lying along the RV diaphragmatic surface. The ICD (Medtronic Micro Jewel II model 7223 Cx) was implanted in a left abdominal pocket with the lead tunneled from the infraclavicular region to the pocket. Implant DFTs were < or = 15 J using a biphasic waveform. DFTs rechecked within 3-month postimplant were unchanged. Lead impedance at implant ranged from 38 to 56 omega, mean 51 omega. Follow-up was 3-21 months (total 82 months) with no electrode dislodgment, lead fractures, or inappropriate discharges. Two of the five patients have had successful appropriate ICD discharges. Transvenous ICD electrode placement can be performed in children as small as 20 kg with the device implanted in a cosmetically acceptable abdominal pocket that is well tolerated. Excellent DFTs can be achieved. This approach avoids a thoracotomy in all but the smallest child, does not require subclavicular placement of the device, and avoids use of a second intravascular coil.

Abdomen↗
PubMed1999

The dimensions of the triangle of Koch in children.

We measured the dimensions of Koch's triangle in children with normal intracardiac anatomy to determine the relation between the size of the triangle of Koch and patient age, weight, height, and body surface area. We found that the dimensions of Koch's triangle varies significantly and directly with patient age and body habitus in this pediatric population.

Age Factors↗
PubMed1999

Clinical course of persistent junctional reciprocating tachycardia.

OBJECTIVE: The purpose of this study is to review the clinical course of persistent junctional reciprocating tachycardia (PJRT) in 21 patients spanning a wide age range to examine the electrophysiologic characteristics of the conduction system in these patients with PJRT, particularly in regards to its incessant nature and to evaluate the long-term response to radiofrequency ablation. BACKGROUND: Persistent junctional reciprocating tachycardia is uncommon, occurring in 1% of patients with supraventricular tachycardia. Its presentation, course and treatment are incompletely characterized. METHODS: The clinical, electrocardiographic, electrophysiologic and echocardiographic data of 21 patients with PJRT were reviewed. RESULTS: In 9 of these 21 patients, the mean tachycardia cycle length increased significantly (p < 0.0001) as the patients grew, from a mean tachycardia cycle length of 308+/-64 ms in the patients less than 2 years, 414+/-57 ms in the patients between 2 years and 5 years, to 445+/-57 ms in the patients greater than 5 years, primarily due to slowing of retrograde conduction in the accessory pathway. Persistent junctional reciprocating tachycardia was associated with impaired ventricular function in 11, improving spontaneously in 4 and, after successful ablation of the accessory pathway, in 7. All patients except one were uncontrolled on one or more medications. Ablation of the accessory pathway was successful in 19 of 21 patients. CONCLUSIONS: We conclude that PJRT is characterized by an onset in early childhood and by an age-related prolongation of the tachycardia cycle length mediated primarily through conduction delay in the concealed, retrogradely conducting accessory pathway. Ablation of the accessory pathway provides definitive treatment for PJRT.

Adolescent↗
PubMed1998

Subsets of transgenic T cells that recognize CD1 induce or prevent murine lupus: role of cytokines.

T cells with T cell receptor (TCR) transgenes that recognized CD1 on syngeneic B cells stimulated B cells to secrete immunoglobulins in vitro. The CD4+, CD8+, or CD4-CD8- T cells from the spleen of the TCR transgenic BALB/c donors induced lupus with anti-double stranded DNA antibodies, proteinuria, and immune complex glomerulonephritis in irradiated BALB/c nude mice reconstituted with nude bone marrow. Injection of purified CD4-CD8- T cells from the marrow of transgenic donors prevented the induction of lupus by the transgenic T cells. Transgenic T cells that induced lupus secreted large amounts of interferon (IFN)-gamma and little interleukin (IL)-4, and those that prevented lupus secreted large amounts of IL-4 and little IFN-gamma or IL-10.

Animals↗
PubMed1998

The effects of age, education, and ethnicity on verbal fluency.

A group of 317 healthy participants between 54 and 99 years of age performed a verbal fluency task. The participants included Chinese, Hispanic, and Vietnamese immigrants, as well as White and African American English speakers. They were given 1 min to name as many animals as possible in their native language. The results showed that more animal names were produced by younger people and those with more education. Language background was also an important factor: The Vietnamese produced the most animal names and the Spanish speakers produced the fewest. The exaggerated difference between these two groups is attributed to the fact that Vietnamese animal names are short (predominantly 1 syllable) while the Spanish animal names are longer than any other language in this study (2 and 3 syllables per word). Finally, although the ethnic groups named different animals, and appeared to vary in the variety of animal names they used, these factors did not affect overall verbal fluency performance.

Age Factors↗
PubMed1998

NASPE expert consensus document: use of i.v. (conscious) sedation/analgesia by nonanesthesia personnel in patients undergoing arrhythmia specific diagnostic, therapeutic, and surgical procedures.

Use of IV (Conscious) Sedation/Analgesia by Nonanesthesia Personnel in Patients Undergoing Arrhythmia Specific Diagnostic, Therapeutic, and Surgical Procedures. This article is intended to inform practitioners, payers, and other interested parties of the opinion of the North American Society of Pacing and Electrophysiology (NASPE) concerning evolving areas of clinical practice or technologies or both, that are widely available or are new to the practice community. Expert consensus documents are so designated because the evidence base and experience with the technology or clinical practice are not yet sufficiently well developed, or rigorously controlled trials are not yet available that would support a more definitive statement. This article has been endorsed by the American College of Cardiology, October 1997.

Anesthesiology↗
PubMed1998

Effects of low-dose dopamine on urine output in oliguric, critically ill, renal transplant patients.

UNLABELLED: Low-dose dopamine (LD-DA) has been used extensively to increase urine output (UO) in critically ill patients. These effects have recently been documented in patients with normal and mildly abnormal renal function. The purpose of this study was to quantitate the effects of LD-DA on UO and urineNa (UNa) excretion in renal transplant (RT) patients, and thereby evaluate the effects of LD-DA on the denervated kidney. METHODS: Five RT patients and 7 non-transplant controls, hospitalized in the surgical intensive care unit (SICU), with serum creatinine (serum Cr) < 2 mg/dL who were oliguric (UO < 0.5 mL/kg/h), received LD-DA (2.5 micrograms/kg/min). None received other diuretics within 12 h, and all had pulmonary artery occlusion pressure (PAOP) > 10 mmHg and CI > 3.0 L/min/m2. UO was measured hourly and averaged for 2 h pre and 6 h during LD-DA. All data are mean +/- SD. RESULTS: APACHE II (14 +/- 4), CI (4.1 +/- 1.2 L/min/m2), PAOP (15 +/- 4 mmHg), HR (98 +/- 16/min), and MAP (83 +/- 10 mmHg) were similar between groups and did not change during LD-DA therapy. Initial serum Cr in the RT group (1.6 +/- 0.4 mg/dL) was greater than that in controls (0.9 +/- 0.24 mg/dL), p < 0.05. Initial UO [0.26 +/- 0.10 mL/kg/h (RT) and 0.31 +/- 0.12 mL/kg/h (controls)] and initial UNa [8 +/- 62 meq/L (RT) and 54 +/- 28 meq/L (controls)] were not different. Urine output increased significantly compared with baseline in both groups [final UO 0.55 +/- 0.14 mL/kg/h (RT) and 0.96 +/- 0.41 mL/kg/h (controls)]. Final UNa [72 +/- 37 meq/L (RT) and 99 +/- 56 meq/L (controls)] were not different from each other or from baseline. CONCLUSIONS: LD-DA increases UO, but not UNa excretion, in RT patients with oliguria, comparably to controls. These data suggest that this effect is predominantly mediated by dopaminergic receptors, since the transplanted kidney is denervated and there were no significant associated changes in hemodynamic parameters during the study.

Creatinine↗