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Biomedical subjects

A Hellström

Publications and source records attributed to A Hellström.

At least 19 recordsLinked to original sources
PubMed1998

Optic disc size and retinal vessel characteristics in healthy children.

PURPOSE: To characterize the optic disc and retinal vessels in healthy children and adolescents. METHODS: Fundus photographs were evaluated by digital image analysis in one hundred healthy Swedish children and adolescents (3-19 years). RESULTS: Median optic disc area was 2.67 mm2 (range, 1.93 to 4.39), median cup area was 0.41 mm2 (range, 0 to 1.45) and median neuroretinal rim area was 2.24 mm2 (range, 1.60 to 3.05). The size of the cup and neuroretinal rim increased with increasing size of the optic disc. There were no correlations between the measured variables and age, sex or refraction. CONCLUSION: The measurements of optic disc size in healthy children, between 3 and 19 years of age, are in accordance with optic disc values found in most studies on adults. The resulting reference intervals may be helpful in clinical pediatric ophthalmology, to facilitate identification of children with abnormal optic disc and retinal vessel morphology.

Adolescent↗
PubMed1998

Midline brain lesions in children with hormone insufficiency indicate early prenatal damage.

The relationships between midline brain morphology, anterior visual pathway morphology and hormonal status in children with impaired growth were studied. Intracranial morphology was studied by magnetic resonance imaging in 47 children (14F, 33M), median age 9.7y (range 2.6-18.7y) undergoing growth hormone treatment (GH; 0.1 U/kg/d). They were chosen to represent various birth sizes and a spectrum of hormone insufficiencies. There was a relationship between GH secretion and the morphology of the neurohypophysis, the pituitary stalk and the anterior visual pathways, i.e. the greater the GH insufficiency, the more abnormal were these structures. The children with anterior visual pathway abnormalities had the lowest GH levels and the smallest adenohypophysis. The association between abnormalities of the anterior visual pathways and the hypothalamo-pituitary structures may reflect a common prenatal neural damage in embryologically and anatomically closely related structures.

Adolescent↗
PubMed1997

Large cups in normal-sized optic discs: a variant of optic nerve hypoplasia in children with periventricular leukomalacia.

OBJECTIVE: To evaluate optic disc morphologic features in children with periventricular leukomalacia (PVL). PATIENTS AND METHODS: Seventeen children with PVL (patient group) were compared with 17 sex- and age-matched, full-term healthy control children (control group). Clinical ophthalmological examination and digital image analysis of fundus photographs were performed in all children. In children with PVL, cerebral imaging was performed. RESULTS: Children with PVL had larger optic disc cupping (P<.02) than did control children. A large proportion of the children with PVL had strabismus, nystagmus, and restricted visual fields. CONCLUSION: Our study indicates that optic nerve hypoplasia in children with PVL is often associated with a normal-sized optic disc with a large cup. This unusual form of optic nerve hypoplasia most likely results from transsynaptic degeneration of optic axons caused by the primary bilateral lesion in the optic radiation.

Adolescent↗
PubMed1997

Tone duration discrimination in Parkinson's disease.

Patients with Parkinson's disease (PD) and healthy controls took a computerized test of tone duration discrimination (TDD) using pairs of tones of 0.4-1.6 sec duration, presented at intervals of 0.5-4 sec. In PD patients as well as controls, TDD was impaired by even slight degrees of cognitive deterioration. PD yielded impaired TDD in females, but not in males. This suggests that the dopamine-powered biological clock, which is vulnerable to PD, is more important for the processing of durations in the 1-sec range in women than in men.

Adult↗
PubMed1997

Eye size in healthy Swedish children and in children with fetal alcohol syndrome.

PURPOSE: This study set out to collect reference data for normal ocular growth and to study the teratological effects of alcohol on eye development. METHODS: Eye size was studied in 92 healthy Swedish children (age 1 month to 16 years) as reference and in 13 children (age 1.4 months to 17 years) with fetal alcohol syndrome (FAS) using ultrasonographic axial length measurements. Another three children with FAS were evaluated by clinical examination only. RESULTS: The control group demonstrated a marked increase in total axial length during the first 2 years of life. Girls with FAS had a shorter total axial length (p = 0.045) than their controls. Both boys and girls with FAS demonstrated a relatively smaller vitreous body than the controls, p = 0.015 and 0.068, respectively. Three children with FAS had severe structural anomalies. CONCLUSION: The observations support previous studies indicating that alcohol has an adverse effect on growth and configuration of the eye.

Adolescent↗
PubMed1997

Perceptual magnet effect in the light of behavioral and psychophysiological data.

Finnish speaking adults categorized synthetic vowels, varying in the frequency of the second formant (F2), as either /y/ or /i/. Two subject groups emerged: "good" and "poor" categorizers. In a /i/ rating experiment, only the good categorizers could consistently label their best /i/ (the prototype, P), being low in the F2 continuum. Poor categorizers rated /i/'s with high F2 values as Ps. In a same/different (AX) discrimination experiment, using the individual Ps and nonprototypes (NPs), it was more difficult for good categorizers to detect small F2 deviations from the P than from an NP (the "perceptual magnet effect"). For poor categorizers, the opposite effect was found. The same stimuli were used to record the mismatch negativity (MMN), an ERP component reflecting preattentive detection of deviations from a standard sound. For the good categorizers the MMNs were lower for Ps than for NPs; for the poor categorizers the MMNs for Ps and NPs did not differ significantly. The results show that individual listeners behaved differently in categorization and goodness rating but in the same way in attentive (AX) discrimination, being the poorest at about the same F2 location. The perceptual magnet effect was indicated in the good categorizers both by behavioral and psychophysiological (MMN) discrimination data.

Adult↗
PubMed1997

Ocular fundus morphology in preterm children. Influence of gestational age, birth size, perinatal morbidity, and postnatal growth.

PURPOSE: To determine the influence of gestational age, birth size, perinatal morbidity, and postnatal growth on fundus morphology in preterm children using digital image analysis of fundus photographs. METHODS: Thirty-nine preterm children (mean postmenstrual gestational age, 29.1 weeks; range, 24.6 to 32) were included in the study. Thirty-nine healthy children, born at term, were used as control subjects. Fundus photographs were obtained at a mean age of 4.8 years (preterm) and 6.1 years (control subjects). RESULTS: There was no difference in optic disc, excavation, or peripapillary crescent area between the two groups. In the group of preterm children, a large optic disc size was associated with a low birth weight (rs = -0.29, P = 0.07), duration of assisted ventilation (rs = 0.43, P = 0.006), and number of blood transfusions (rs = 0.33, P = 0.04). The girls born prematurely showed a negative relation between the length of gestation and the area of the optic disc (r2 = 0.28, P = 0.009). No such relation was found in boys. The preterm children had increased tortuosity of retinal vessels (P < 0.001 and P < 0.002 for arteries and veins, respectively) and reduced number of vascular branching points (P < 0.001) compared with those of the control subjects. There were no associations between these vascular abnormalities and the perinatal and postnatal variables studied. CONCLUSIONS: No difference in optic disc morphology between preterm children and control subjects was found. However, preterm birth seems to affect the retinal vascular pattern close to the optic disc, independently of retinopathy of prematurity. Among the girls born preterm, optic disc size was negatively correlated to gestational age.

Birth Weight↗
PubMed1996

Early effects of coronary artery bypass surgery and cold cardioplegic ischemia on left ventricular diastolic function: evaluation by computer-assisted transesophageal echocardiography.

OBJECTIVE: Although left ventricular (LV) systolic function undergoes a temporary decrease after cardiopulmonary bypass (CPB) in patients undergoing coronary artery bypass grafting (CABG), data on the effects of CABG and cardioplegic arrest on LV diastolic function are contradictory. The objective of the present study was to further evaluate the effects of CABG and CPB on LV diastolic function. DESIGN: A prospective study. SETTING: A multi-institutional investigation at a university hospital. PARTICIPANTS: 20 patients on beta-receptor antagonists, scheduled for CABG and with a preoperative ejection fraction over 0.5. INTERVENTIONS: Central hemodynamic measurements, transesophageal LV short-axis images, and mitral Doppler flow profiles were obtained before and after volume loading that in turn was performed both before surgical incision and after weaning from CPB. MEASUREMENTS AND MAIN RESULTS: Heart rate, cardiac output, and peak atrial filling velocity increased; systemic vascular resistance decreased; whereas stroke volume, LV area ejection fraction, deceleration rate and slope of early diastolic filling, time-velocity integral of early diastolic filling, and the ratio between early and atrial peak filling velocity were unchanged post-CPB compared with pre-CPB. LV end-diastolic stiffness that was calculated for each patient pre-CPB and post-CPB using the formula: P = B*eS*A), where P is the LV filling pressure and A is the end-diastolic short-axis area, was unchanged post-CPB compared with pre-CPB. CONCLUSIONS: Both the active and passive components of LV diastolic function are well maintained shortly after CABG and cardioplegic arrest in patients with a good preoperative systolic LV function.

Coronary Artery Bypass↗
PubMed1996

Growth hormone status in six children with fetal alcohol syndrome.

OBJECTIVE: Prenatal alcohol exposure may cause fetal alcohol syndrome (FAS), which is associated with pre- and postnatal retardation. MATERIALS AND METHODS: Spontaneous 24-h growth hormone (GH) secretion was measured in six prepubertal short children with FAS (two boys and four girls) aged 4-14 years. The response to a GH stimulation test, and levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) were also measured. Comparisons were made between the children with FAS and healthy children of both normal and short stature, as well as children born small for gestational age (SGA). RESULTS: There were no differences in the mean area under the curve above the baseline or the maximum level of GH during a 24-h period (GHmax) between the children with FAS and the reference groups. However, the estimated rate of spontaneous 24-h GH secretion in children with FAS was similar to that of children born SGA, but lower than in children of normal stature (p = 0.02). The plasma concentrations of IGF-I and IGFBP-3 were in the lower parts of the normal range. CONCLUSION: We conclude that GH secretion in short children with FAS is similar to that in short children born SGA; that is, in the lower range of normal children.

Adolescent↗
PubMed1996

Fetal alcohol syndrome--an ophthalmological and socioeducational prospective study.

BACKGROUND: The eye is a sensitive indicator of adverse effects of prenatal alcohol exposure. Anomalies of the eyes and their adnexa are known to be associated with the fetal alcohol syndrome (FAS), although long-term effects of these malformations are unknown. DESIGN: A prospective ophthalmologic follow-up (median, 11 years; range, 4 to 19 years) was performed in 25 children with FAS. Their social situation and educational status were also investigated. RESULTS: All but one of the children had ophthalmologic abnormalities. Fundus anomalies were observed in 23 children, of whom 19 had optic nerve hypoplasia. Thirteen children had concomitant strabismus. Microphthalmos, buphthalmos, phthisis, microcornea, coloboma of the iris and uvea, blepharoptosis, cataract, persistent hyperplastic primary vitreous, and nystagmus were observed in single cases. The dysmorphology of the eyes remained unchanged during the follow-up period. In 2 children with severe mental retardation and, initially, very poor vision, the severe visual handicap persisted. Seventeen children had an initial visual activity > or = 20/70, which remained unchanged in 10 children and improved in 7 children, despite the presence of optic nerve hypoplasia in 14 of the children. Ten mothers died, 8 of them because of alcohol-related diseases, and only 4 of the mothers were able to take care of their children. Sixteen children went to schools for the mentally retarded, and only 3 children had a normal school education without extra teaching assistance. CONCLUSIONS: In children with FAS, the major sequela, ie, brain, damage, remains despite extensive medical, educational, and social support. The presence of ophthalmic signs, which persisted but did not deteriorate during the follow-up period, strengthens the diagnosis of FAS, and the high frequency of ocular involvement indicates the importance of a complete ophthalmologic evaluation in children with FAS.

Adolescent↗
PubMed1995

Morphometry of the optic nerve and retinal vessels in children by computer-assisted image analysis of fundus photographs.

BACKGROUND: The retinal fundus in childhood has a different morphology than in adulthood. Existing methods are not suitable for evaluation of fundus photographs from children. Therefore, a new method for quantitative analysis of fundus morphology utilizing a personal computer-assisted digital mapping system was developed. METHODS: A CCD flatbed scanner is used to digitize fundus photographs, producing computer images which are analyzed on an IBM/AT computer. Area measurements of the optic disc, excavation and peripapillary crescent are made, as well as determinations of the length, branching, tortuosity and distribution of the retinal vessels on the fundus surface. RESULTS: Determination of the inter- and intra-observer variability of the computer-assisted image analysis technique demonstrated good reproducibility. The method is demonstrated using fundus photographs of six normal children and six children with the fetal alcohol syndrome. Typical variations in appearance of optic disc and retinal vessels are seen. CONCLUSION: The system is unique in measuring both the optic nerve head and the retinal vessels and is therefore especially useful for detailed studies of normal and abnormal development of these structures in children.

Adolescent↗
PubMed1995

The effects of nitrous oxide on left ventricular systolic and diastolic performance before and after cardiopulmonary bypass: evaluation by computer-assisted two-dimensional and Doppler echocardiography in patients undergoing coronary artery surgery.

We investigated the effects of nitrous oxide (N2O) on central hemodynamics and left ventricular systolic and diastolic function in 25 patients undergoing coronary artery bypass surgery. All patients were receiving beta-blockers and had good left ventricular function. Global and regional systolic left ventricular performance and diastolic function were determined by computer-assisted analysis of transesophageal echocardiographic (TEE) images, and mitral Doppler flow profiles, respectively. The patients were anesthetized with fentanyl and ventilated with oxygen in air. Hemodynamic and TEE measurements were obtained before and after the introduction of N2O in oxygen (60%/40%), before and after cardiopulmonary bypass (CPB). N2O reduced mean arterial pressure, heart rate, stroke volume, and cardiac output both before and after CPB. Left ventricular global area ejection fraction (GAEF) was not changed by the introduction of N2O, either before or after CPB. N2O induced a significant change in regional wall motion after, but not before CPB, as assessed by the relationship between segmental area ejection fraction (SAEF) and GAEF. Analysis of the mitral flow profile indicated an increase in early diastolic relaxation in the pre-CPB period after introduction of N2O, that was absent in the post-CPB period. We conclude that N2O induces regional wall motion abnormalities and possibly diastolic dysfunction post-CPB.

Blood Pressure↗
PubMed1995

Micturition habits and incontinence at age 17--reinvestigation ofa cohort studied at age 7.

OBJECTIVE: To study the epidemiology of micturition disturbances in teenagers. SUBJECTS AND METHODS: A subsample of 1034 teenagers previously evaluated at age 7 years was reinvestigated 10 years later. A postal questionnaire was used and a response rate of 71% (736) obtained. Those who reported bladder symptoms were contacted by telephone for a detailed history concerning imperative urge, daytime incontinence, emptying difficulties and bedwetting. RESULTS: There was a general decrease in the frequency and intensity of symptoms from 7 to 17 years of age. At age 17 at least one symptom was reported by 5.9% of the girls and 0.9% of the boys. Overall the symptoms were regarded as mild or moderate. CONCLUSION: At age 17 years, micturition disturbances were reported infrequently and few subjects wanted medical help.

Adolescent↗
PubMed1993

The normal distribution in scaling subjective stimulus differences: less "normal" than we think?

The Gaussian, or "normal," distribution is routinely used to model distributions of subjective quantities. This practice rests on a trust in the central limit theorem, yet this theorem does not cover the case of a mixture of Gaussian distributions with different standard deviations, which yields a distribution that is heavier tailed than the Gaussian. In psychophysical judgment experiments, this may result, for example, from fluctuating or interindividually varying attention. Two candidates for describing this commonly encountered type of distribution are the logistic distribution and the t distribution with a small number of degrees of freedom. In reanalyses of experimental data on three-category loudness comparisons, as well as in a Monte Carlo simulation, t(4) was found to model the underlying mixed inter- and intraindividual distribution of subjective loudness differences quite satisfactorily.

Humans↗
PubMed1991

Association between urinary symptoms at 7 years old and previous urinary tract infection.

The association between current micturition habits and previous urinary tract infection was analysed among 3553 school entrants aged 7 years by means of a questionnaire. A high incidence of urinary infection, confirmed by urine culture, was found (145 (8.4%) in the 1719 girls and 32 (1.7%) in the 1834 boys). There was a significant association between current symptoms that were suggestive of disturbed bladder function and previous urinary tract infection, but only among girls who were over 3 years of age at the time the first episode was diagnosed.

Age Factors↗
PubMed1987

The relationship between obesity-related metabolic factors and vascular changes in early hypertension.

The relationships of obesity, glucose metabolism and hormonal variables to mean arterial pressure (MAP) regional vascular resistance and signs of structural vascular changes, were determined in 70 men aged 49 years with normal to mildly elevated MAP randomly selected from a population sample. Regional vascular resistances and signs of structural vascular changes were measured in the calf by plethysmography at rest and during maximal dilatation, and in the kidneys by renal blood flow determination during graded subpressor doses of angiotensin II. MAP was positively correlated to body fat, waist circumference, fat cell size, and to blood glucose 60 minutes after an oral load. This supports an association between central obesity, impairment of glucose tolerance and hypertension. MAP was, however, unrelated to sodium intake, blood volume and indices of sympathetic nervous activity and the renin-angiotensin system. Resting vascular resistance in the calf was unrelated to MAP, while renal vascular resistance rose significantly with increasing MAP. Signs of structural change were significantly correlated to MAP in both these vascular areas. These signs were also associated with central obesity of the hypertrophic type and with impairment of glucose tolerance, even when the association to MAP was accounted for. These factors may be involved in the pathogenesis of the structural adaptation of resistance vessels as hypertension develops.

Blood Glucose↗