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Biomedical subjects

H Helgason

Publications and source records attributed to H Helgason.

12 recordsLinked to original sources
PubMed2004

Recovery of astaxanthin from seafood wastewater utilizing fish scales waste.

The paper presents basic data on astaxanthin adsorption from fisheries wastewater to fish scales. This process has been proposed to be applicable in fisheries and shrimp waste management [Helgason, Recovery of compounds using a natural adsorbent, Patent WO 01/77230, 2001]. The innovative feature of the method is the application of a solid waste (fish scales) as a natural adsorbent for a carotenoid pigment (astaxanthin) from the seafood industry wastewater. The model investigations were performed with pure synthetic carotenoids to exclude the role of matrix in which astaxanthin is present in the wastewater. Under the experimental conditions used, the maximum loading capacity of astaxanthin onto the scales is 360 mg kg(-1) dry wt. Studies of the thus formed value added product indicated that drying causes significant loss of astaxanthin activity. Due to the effective filtration characteristics of the studied sorption material, we suggest the scale/astaxanthin sorption process to be suitable for treatment of wastewater from different industries.

Adsorption↗
PubMed2004

The influence of partial or total thymectomy during open heart surgery in infants on the immune function later in life.

Infants undergoing open heart surgery often have all or part of their thymus removed. The activity of the immune system has not been investigated thoroughly in these children, and only shortly after the operation. Therefore, it was decided to investigate the activity of the immune system in more detail in children several years after their operation. Peripheral blood samples from 19 children who had undergone open heart surgery during their first months of life was collected (study group) and from 19 age- and gender-matched children (control group). The activity of the immune system was evaluated by measuring the number of different cell types in peripheral blood, the phenotype of lymphocytes and the response of T cells following in vitro stimulation by mitogen, tetanus toxoid and measles antigen. The study group had significantly lower counts of total lymphocytes, which was reflected in a lower number of T cells but not B cells. Furthermore, the study group had significantly lower proportion of T cells (CD3(+)) and helper T cells (CD4(+)), but not cytotoxic T cells (CD8(+)). The level of neutrophils in peripheral blood was significantly higher in the study group. This may indicate enhanced innate immunity when the acquired immunity is defective. The results indicate a shift to extrathymic T cell maturation, which is less efficient for CD4(+) helper cells than for CD8(+) cytotoxic cells.

Antigens, Viral↗
PubMed1990

Role of lung biopsy in patients undergoing a modified Fontan procedure.

Fifty-six patients undergoing a modified Fontan procedure from 1977 to 1985 had lung tissue available from the perioperative period (n = 51) or recent palliative procedure (n = 5) (37 biopsy, 12 autopsy, 7 biopsy and autopsy). Twenty-six patients had tricuspid atresia, and 30 had other causes of functional univentricular heart. Pulmonary arterial structure was classified by both the Heath-Edwards and morphometric scales. Biopsy and autopsy grades were identical except for a minor difference in Heath-Edwards scale in one case. Elevated preoperative mean pulmonary artery pressure (greater than 15 mm Hg) was associated with medial hypertrophy (p = 0.04), although six patients with normal pulmonary artery pressure had medial hypertrophy and six patients with mean pulmonary artery pressure greater than 15 mm Hg did not have medial hypertrophy. Medial hypertrophy was a possible risk factor in patients with univentricular heart: Patients with medial hypertrophy had a ninefold greater risk of death (p = 0.08). Controlling for confounding variables did not alter this result (0.06 less than or equal to p less than or equal to 0.10). Medial hypertrophy was not a risk factor for death in patients with tricuspid atresia: Four had this feature and each survived. Four patients with tricuspid atresia died and none had medial hypertrophy. A mean transpulmonary pressure gradient was measured on the first postoperative day in 45 patients. In patients with medial hypertrophy there was a trend toward a higher gradient (p = 0.13). All patients with medial hypertrophy who had this measurement (n = 9) had a transpulmonary pressure gradient of 7 mm Hg or greater, whereas this was true in only 18 of 36 without medial hypertrophy (p = 0.007). On the basis of an evaluation of medial hypertrophy, we conclude that biopsy does not aid in selection of patients with tricuspid atresia for a Fontan procedure; its role in patients with univentricular heart is uncertain.

Adolescent↗
PubMed1988

Comparison of the oral and intravenous routes for treating asthma with methylprednisolone and theophylline.

To compare intravenous and orally administered corticosteroids and theophylline in treating acute episodes of airways obstruction, patients with recent worsening of obstructive symptoms were randomly divided into two groups. Group A received methylprednisolone, 80 mg/24 h, and aminophylline by continuous infusion. Group B received a comparable dose of a sustained-release theophylline and methylprednisolone, 80 mg in two equally divided doses, by mouth. Assessment of response was based on daily spirometric tests and evaluation of dyspnea and wheezing. Arterial blood gas and serum theophylline levels were also measured. The groups were comparable with respect to age, sex distribution, smoking history, and spirometric evidence of obstruction. Initial spirometric test results showed moderate obstruction, equal in the two groups. Obstruction improved markedly by both spirometric and clinical criteria in the four-day study period. The improvement in FEV1 and dyspnea index was slightly greater for group B, but the differences were not significant. We conclude that oral administration of steroids and theophylline is as effective as intravenous use in treating hospitalized patients with moderate exacerbations of airways obstruction.

Acute Disease↗
PubMed1987

Balloon dilation of the aortic valve: studies in normal lambs and in children with aortic stenosis.

To evaluate the risks of and optimal method for valve dilation in aortic stenosis, balloons of different sizes were used to dilate the normal aortic root in 16 lambs and then stenotic valves in 15 children. In the lambs, inflated balloon to aortic anulus diameter ratios ranged from 0.9 to 1.5. These hearts were examined immediately after the procedure. Ratios of 0.9 to 1.1 did not produce significant damage to the left ventricular outflow tract, whereas those of 1.2 to 1.5 produced tears or hematomas, or both, of the aortic valve leaflets (n = 3), mitral valve leaflets (n = 4) and interventricular septum (n = 4). The 15 patients, aged 10 days to 15 years, underwent 16 balloon aortic valvotomy procedures. The balloon-aortic anulus ratio ranged from 0.67 to 1.1 (mean 0.90). The average pressure gradient decreased 69% and, overall, the peak systolic gradient decreased from 86 +/- 21 to 28 +/- 14 mm Hg (p less than 0.01) and the aortic valve area increased from 0.44 +/- 0.11 to 0.73 +/- 0.22 cm2/m2 (p less than 0.01). Immediately after the procedure an increase in aortic regurgitation was noted in 8 (57%) of 14 patients, but was never greater than 3+ and has been well tolerated. Other early complications encountered consisted of transient left bundle branch block in two patients, temporary femoral artery occlusion in three and femoral artery rupture requiring operative management in one infant. Balloon valvotomy can reduce the transvalvular gradient in most patients with valvular aortic stenosis when a balloon less than 1.1 times the aortic root diameter is used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Extending the limits for modified Fontan procedures.

During the early development of atriopulmonary anastomotic operations (Fontan-Kreutzer), a number of physiologic and anatomical limits were proposed by the Fontan group as selection criteria. Among 167 consecutive patients undergoing modified Fontan procedures from 1973 through 1985, 109 (65%) patients exceeded one or more of the original selection criteria in areas of age, anomalies of systemic or pulmonary venous connection, pulmonary artery distortion, and pulmonary artery pressure. Twenty-six patients had a mean pulmonary artery pressure greater than 15 mm Hg, with 16 operative survivors (62%). Nineteen patients had anomalies of systemic and/or pulmonary venous connection, and 16 survived (84%). There were 44 patients under the age of 4 years, and 26 survived (59%). Twenty-five patients were older than 15 years, and 23 (92%) survived the Fontan procedure. Pulmonary artery distortion, relating to prior palliative operations, was found in 34 patients. Seventeen of these 34 survived a modified Fontan procedure (50%). Twenty-six patients had a pulmonary arteriolar resistance more than 2 Wood units times square meter, and 14 survived (54%), whereas 81 of 93 with a pulmonary arteriolar resistance of less than 2 U X m2 survived (87%). Multivariate analysis showed that pulmonary arteriolar resistance and pulmonary artery distortion had a significant, negative impact on survival, but age and anomalies of systemic and/or pulmonary venous connection did not. Pulmonary artery pressure was not an independent predictor of outcome. The results show that the original criteria may be exceeded in the areas of age and anomalies of pulmonary or systemic venous connection. Pulmonary artery pressure alone should not contraindicate a Fontan procedure if pulmonary arteriolar resistance is low. Pulmonary artery distortion from a prior palliative operation and elevated pulmonary arteriolar resistance increase the risk of a Fontan procedure.

Adolescent↗
PubMedDate not supplied

Exercise-induced hypertension after corrective surgery for coarctation of the aorta.

The purpose of this investigation was to study exercise-induced hypertension after surgical repair of coarctation of the aorta (CoA). Groups of 27 patients with CoA and 27 healthy control subjects, 6-21 years old, were exercised to exhaustion using the Bruce protocol. Fourteen patients had undergone surgery during the first year of life (group A), and 13 patients had been operated on later (group B). The pulse rate and systolic blood pressures (BP) in the arm and leg were measured before, during, and after exercise to evaluate changes in the BP and the arm/leg BP gradient with exercise. The systolic BP was significantly higher in the patients than in the controls at all stages of the exercise test (p < 0.01), as was the arm/leg BP gradient both before and after exercise (p < 0.01); the latter increased significantly with exercise in the patient group (p < 0.05). We found hypertension to be a more common and severe problem in group B patients, who had higher blood pressures than their controls at rest and during exercise (p < 0.05). Exercise-induced hypertension was also more common in group B (23%) than in group A (7%). We conclude that exercise-induced hypertension and recoarctation are problems in postoperative CoA patients. Moreover, exercise-induced hypertension is more common in patients with CoA operated on after the first year of life.

Adolescent↗
PubMedDate not supplied

Echocardiographic evaluation of systolic and diastolic function in postoperative coarctation patients.

Postoperative coarctation (CoA) patients are often found to have signs of persistent myocardial dysfunction. M-mode echocardiography was performed to study left ventricular (LV) size, mass, and systolic function and Doppler ultrasonography to study LV filling and flow velocity in the LV outflow tract and aorta in 28 "healthy" postoperative CoA patients (5-21 years) and 28 age- and sex-matched controls. The early (E) and late (A) diastolic transmitral velocities were significantly higher in the patient group than in the controls (p < 0.05). Other diastolic parameters (isovolumic relaxation time, E/A ratio, and deceleration time of the early diastolic velocity) were similar in the two groups (p = NS). The left atrial diameter, LV wall average, end-diastolic diameter of the LV and LV mass were higher in the patients than controls (p < 0.05). The patients also had a higher stroke volume, cardiac output, and cardiac index than the controls (p < 0.01). The fractional shortening was similar in the two groups (p = NS). Blood flow velocities in both the LV outflow tract and aorta were higher in the patients than the controls (p < 0.0002). We found LV hypertrophy with signs of a hyperdynamic circulation (increased cardiac index and stroke volume) in our patients. An increase in A is associated with LV hypertrophy and seems to be a sensitive marker of diastolic abnormality. The rise in E is paradoxical but has been seen in other studies. The increased blood flow velocity in the LV outflow tract suggests obstruction to LV outflow and increased flow in the descending aorta is due to residual coarctation.

Adolescent↗
PubMedDate not supplied

Spontaneous closure of atrial septal defects.

Atrial septal defects (ASDs) are found more frequently in the pediatric population than in adults, and improved diagnostic techniques with echocardiography (2DE) and Doppler facilitate diagnosis so that repair is possible at an optimal time. The purpose of our investigation was to study the size of ASDs at diagnosis, how size changes during follow-up, and to explore the relationship between size at diagnosis and need for surgery. We reviewed the medical records of all patients in Iceland with the diagnosis of ASD born between 1984 and 1993. ASD was confirmed by 2DE in all patients and defects smaller than 4 mm were excluded. ASD size was measured by 2DE from subxyphoid long and short axis views. There were 91 patients-29 males and 62 females. Four patients died from causes other than the heart defect and had not been operated upon. Seven patients with ASD primum and sinus venosus defects were excluded from analysis. There were 29 patients with a 4 mm defect, 17 patients with 5 or 6 mm defects, 8 patients with 7 or 8 mm defects, and 26 patients had defects >8 mm. In the 4 mm group, in 26 patients (89%) the ASD closed spontaneously or decreased in size, and 1 patient had been operated upon. In the 5 or 6 mm group, 15 of 19 ASDs (79%) had closed spontaneously, and 2 patients (9.5%) had been operated upon. In the 7 or 8 mm group, 1 of 6 ASDs (16.6%) had closed spontaneously and 3 had been closed surgically. In the >8 mm group, 1 of 24 ASDs had closed spontaneously and 20 (91%) had been closed surgically. We conclude that defects smaller than 6 mm in diameter are very likely to close spontaneously although follow-up is necessary. Defects larger than 8 mm have a high probability requiring operative closure.

Blood Flow Velocity↗
PubMedDate not supplied

Management of neonatal hip instability: an analysis of the efficiency in a consistent treatment program.

The efficiency of a consistent treatment program for children with neonatal hip instability (NHI) was analyzed. Of 165 children who were referred to the orthopedic department with suspected NHI, 91 children had unstable hips and were treated with a von Rosen splint for 8 weeks; 74 children were found to have stable hips and were not treated, but were followed up in the same way as the treated children. All treated and untreated children developed clinically and radiologically normal hips. Treatment with a von Rosen splint is reliable, and with few exceptions 8 weeks is sufficient time for treatment of NHI.

Child, Preschool↗