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Biomedical subjects

H Lou

Publications and source records attributed to H Lou.

At least 91 records · Page 5Linked to original sources
PubMed1990

Redistribution of cerebral activity during childhood.

Data on the functional development of brain structures in early childhood are scarce. Cognition changes markedly from pre-school age to school age, and we thought it of interest to examine the level of functional activity of selected brain regions. Nine preschool children were studied and compared with eight school children and eighteen adults. Xe133 emission tomography was used for determination of regional cerebral blood flow (rCBF). It was demonstrated that activity in the striatal regions is low in early childhood. In school age the proportion of flow to these regions is increased by about 11-14 per cent (difference between medians). Perfusion of the occipital lobes decreased with age when studied with open eyes and closed eyes, possibly reflecting loss of synapses and decreased plasticity.

Adolescent↗
PubMed1990

Plasma amino acids in term neonates and infants with phenylketonuria before and after institution of the diet.

The plasma amino acid concentrations were measured in 12 neonates with phenylketonuria (PKU). Blood samples were taken when fasting and two hours after a meal. The individual amino acid concentrations, the glycine/valine ratios, and the total amino acid concentrations were mutually compared and also compared to reference intervals. When the diet was instituted and plasma phenylalanine decreased, we observed a normalization of the postprandial response of isoleucine, leucine, tyrosine, and valine.

Amino Acids↗
PubMed1990

Plasma amino acids in phenylketonuric children treated either with phenylalanine-free amino acids or a protein hydrolysate.

The plasma amino acid concentrations were measured in 10 children with phenylketonuria (PKU) on the phenylalanine-free amino acid mixture Phenyldon and 9 PKU children on the phenylalanine-free protein hydrolysate Albumaid. The blood samples were taken fasting and two hours after the meal. The individual amino acid concentrations, the glycine/valine ratios, and the total amino acid concentrations were mutually compared and also compared to reference intervals. No differences of the concentration of phenylalanine on the two diet formulas were observed. Children on Phenyldon showed fasting and postprandial isoleucine higher than the reference intervals. Furthermore, a postprandial increase of several amino acids was observed on both diet formulas. This response was statistically significant in children on Phenyldon.

Amino Acids↗
PubMed1990

The expression of placental alkaline phosphatase (PLAP) and PLAP-like enzymes in normal and neoplastic human tissues. An immunohistological survey using monoclonal antibodies.

The immunohistological expression of placental alkaline phosphatase (PLAP) and PLAP-like enzyme was studied in frozen sections from a wide variety (n = 254) of normal and malignant tissues using monoclonal antibodies reactive with PLAP (H317) and PLAP/PLAP-like enzyme (H17E2; H315). PLAP/PLAP-like reactivity was seen in normal thymus, and foetal and neonatal testis, and in 21 out of 22 malignant germ cell tumours (GCTs), but was also found in normal endocervix, normal Fallopian tube and in 28 out of 167 non-GCTs (particularly in ovarian and proximal gastrointestinal tract tumours). Positivity for true PLAP (as demonstrated with H317) was seen in term placenta, in endocervix, and in Fallopian tube (but not in other normal tissues) and was commonly found in ovarian and proximal gastrointestinal tract tumours. Reactivity with H317 was unusual in malignant GCTs (2 out of 22 cases). These findings confirm that PLAP/PLAP-like positivity is a highly sensitive immunohistological marker for malignant GCTs, but one which by itself is of only moderate specificity. Furthermore, expression of true PLAP is rare in GCTs and favours instead an origin from the ovary or proximal gastrointestinal tract. The results also indicate that the predominant heat-stable alkaline phosphatase species in normal foetal and neonatal testis, and in thymus has a similar immunohistological profile to that found in malignant GCTs, and is a PLAP-like enzyme ("germ cell alkaline phosphatase") distinct from true PLAP. The occurrence of this marker in GCTs would appear to reflect increased eutopic production of an enzyme present in trace amount in corresponding normal tissues rather than a genuine example of ectopic expression.

Alkaline Phosphatase↗
PubMed1990

[Effectiveness evaluation and cost-effectiveness estimate for diarrhea control by environment improvement in rural area].

Diarrhea diseases had been controlled by improving water supplies and excreta disposal facility in Changge county, Henan. In 1983, the morbidity rate of diarrhea was 48% in trial village. After central water supply was established in 1986, the rate was decreased to 28.2%, and was further reduced to 11.08% by both improvement of water supplies toilets. In comparison with 1983, the reduction of the rate was 76.9%. The results showed that the two measures had a great impact on reduction of patients with diarrhea during the peak period from June to Oct. The patients below age four were three fourth reduced by improved water supply only. In comparison with control village, the morbidity rates of all age groups were reduced 54-79% by both improvement of water supplies and toilets. But there was no significant difference in the distribution of the pathogens. Both measures cost 46 Yuan per capita. The annual benefit of 23.5 Yuan per capita was obtained from reducing the diseases and saving working force and fertilizer. It was estimated that the total costs will be paid in 2 years and cost-benefit ratio will be 4.4 after 2 years.

Cost-Benefit Analysis↗
PubMed1989

Ossification of the cricothyroid membrane following minitracheotomy.

We describe a case in which a repeat minitracheotomy (MT) could not be performed 2 months after the first. The cricothyroid membrane seemed calcified and histological examination showed scar formation with dystrophic calcification and heterotopic bone formation. Scar formation following MT may have caused these alterations making repeat access to the airway through the membrane impossible.

Carcinoma, Squamous Cell↗
PubMed1989

Heterogeneity of cerebral vasoreactivity in preterm infants supported by mechanical ventilation.

The reaction of cerebral blood flow to acute changes in arterial carbon dioxide pressure (PaCO2) and mean arterial blood pressure was determined in 57 preterm infants supported by mechanical ventilation (mean gestational age 30.1 weeks) during the first 48 hours of life. All infants had normal brain sonograms at the time of the investigation. In each infant, global cerebral blood flow was determined by xenon-133 clearance two to five times within a few hours at different levels of PaCO2. Changes in PaCO2 followed adjustments of the ventilator settings. Arterial oxygen pressure was intended to be kept constant, and mean arterial blood pressure fluctuated spontaneously between measurements. The data were analyzed by stepwise multiple regression, with changes in global cerebral blood flow, PaCO2, mean arterial blood pressure, and postnatal age or intracranial hemorrhage used as variables. In infants with persistently normal brain sonograms, the global cerebral blood flow-carbon dioxide reactivity was markedly lower during the first day of life (mean 11.2% to 11.8%/kPa PaCO2) compared with the second day of life (mean 32.6/kPa PaCO2), and pressure-flow autoregulation was preserved. Similarly, global cerebral blood flow-carbon dioxide reactivity and pressure-flow autoregulation were present in infants in whom mild intracranial hemorrhage developed after the study. In contrast, global cerebral blood flow reactivity to changes in PaCO2 and mean arterial blood pressure was absent in infants in whom ultrasonographic signs of severe intracranial hemorrhage subsequently developed. These infants also had about 20% lower global cerebral blood flow before hemorrhage, in comparison with infants whose sonograms were normal, a finding that suggests functional disturbances of cerebral blood flow regulation. Several perinatal factors were tested, but only birth after abruptio placentae was related to subsequent periventricular hemorrhage (p = 0.037).

Age Factors↗
PubMed1989

Tetrahydrobiopterin and Parkinson's disease.

Two patients with Parkinson's disease were treated with 1 g tetrahydrobiopterin (BH4) for 5 days. Clinical improvement was not observed. In the cerebrospinal fluid (CSF) a 4-8 fold increase in the concentration of homovanillic acid (HVA), and a 3-fold increase in the concentration of 5-hydroxyindole acetic acid (5-HIAA) was measured. However, the concentration of HVA reached, was only approximately half as high, as that of patients treated with madopar (DOPA + benserazid). In urine, the excretion of HVA increased 13-37 fold, when the patients were treated with madopar, whereas no increase in the HVA excretion was measured after the BH4 administration. Additionally, 2 patients with Parkinson's disease were treated with 1 g BH4 in combination with 15 g tyrosine for 3 days, and 1 parkinsonian patient was treated with 15 g tyrosine daily for 7 weeks. No increase in the CSF concentrations of HVA or 5-HIAA was observed. The results suggest, the BH4 in the dosage used, is not effective in the treatment of Parkinson's disease.

Adult↗
PubMed1988

Poor reversibility of EEG abnormality in hypotensive, preterm neonates.

Twenty-four infants, 32 weeks of gestation or less, were studied with continuous recording of amplitude integrated electroencephalogram (aEEG) and repeated Doppler ultrasound determination of the mean blood flow velocity in the internal carotid artery (cMFV). The recording was started after the initiation of mechanical ventilation for respiratory distress. Of twelve infants receiving blood or albumin transfusion to expand the intravascular volume and in whom adequate data were available, both mean arterial blood pressure and cMFV increased in eight, and cMFV but not blood pressure in further two. In the present circumstances we consider the cMFV increases to represent true increases in cerebral blood flow. aEEG burst rate increased distinctly in five of the twelve infants during or immediately following transfusion, but did only approach the level of the four non-transfused infants after several hours, indicating a dysfunction of neural tissue not readily reversible by improved blood flow.

Blood Flow Velocity↗
PubMed1987

Severe hypocarbia in preterm infants and neurodevelopmental deficit.

We report significant neurological abnormality at 18 months of age in 3 of 7 very low birth weight infants (less than or equal to 1,500 g), who during mechanical ventilation inadevertently became severely hypocarbic (arterial carbondioxide tension less than 2.0 kPa (15 mmHg)) at some time during the first 24 h of life. Although the number is small the outcome was significantly worse than the outcome in two fairly similar groups of infants selected as controls (p = 0.026). The infants in one of the control groups were also mechanically ventilated but remained normocapnic. Germinal layer haemorrhage (GLH) was more frequent among these infants compared with the severely hypocarbic infants (p = 0.022). The infants in the other control group was not mechanically ventilated. In all the severely hypocarbic infants the Bayley mental developmental index uncorrected for prematurity was at or below the median for the total sample (p = 0.01). The results suggest that neonatal cerebral ischaemia, for instance due to hypocarbia, is of greater prognostic significance than GLH.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

EEG depression and germinal layer haemorrhage in the newborn.

Amplitude integrated EEG (aEEG) recordings from 32 mechanically ventilated infants, gestational age 32 weeks or less, were analysed. All recordings were started within 24 h of birth and continued for at least 50 h. Germinal layer haemorrhage (GLH) was diagnosed by repeated ultrasonography. In six infants neither GLH nor hypocalcaemia were diagnosed; aEEG in these infants rapidly became more active after birth: at 30 h of age continuous background activity was present for more than 20% of the time, and a seizure-like pattern was exceptional. In seven infants without GLH but with hypocalcaemia and other signs of metabolic derangement, continuous background activity appeared later and seizure-like activity was frequent. In the infants with GLH, depression of the background activity was apparent. This finding was particularly distinct in the presence of severe haemorrhages. Four infants developed GLH after 30 h of age. All these infants had depressed aEEG before the development of GLH, with less than 20% continuous activity at 30 h of age. In ten infants an analysis of the aEEG during the occurrence of GLH was possible. In six of these, cortical electrical activity decreased. Due to the limitation of GLH timing, it was not possible to decide whether this decrease closely preceded or followed GLH. We suggest that GLH primarily occurs in brains with a preceding metabolic and neurophysiologic abnormality, and that further functional deterioration is caused by the most severe haemorrhages.

Cerebral Hemorrhage↗
PubMed1986

Dietary problems of phenylketonuria: effect on CNS transmitters and their possible role in behaviour and neuropsychological function.

Thirty years ago it was observed that the synthesis of serotonin, dopamine and norepinephrine was impaired in untreated phenylketonuria (PKU) as judged either by a decreased concentration in the blood or decreased excretion in the urine of these neurotransmitters, or of their metabolites, 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA). Fifteen years later, when early treatment of PKU with a phenylalanine restricted diet was routinely introduced, an inverse relationship was found between phenylalanine levels and the urinary excretion of dopamine and serotonin. An inverse relationship between blood phenylalanine levels and cerebrospinal fluid (CSF) concentrations of HVA and 5-HIAA has repeatedly been reported during the past 10 years. Recently, the effect of the discontinuation of diet in PKU on the synthesis of dopamine, norepinephrine and serotonin has been examined, and the possible relationship between low levels of these neurotransmitters and impaired performance on neuropsychological tests has been evaluated. In some PKU patients the performance on neuropsychological tests of higher integrative function is impaired after discontinuation of diet, especially when blood phenylalanine values exceed 1200 mumol/L, and the patients often complain of lack of concentration and emotional instability. When these patients return to a 'relaxed' phenylalanine restricted, tyrosine enriched diet, the impaired neuropsychological and behavioural functions appear to be reversible. One mechanism may involve an impaired synthesis of dopamine and serotonin, as the improvement is accompanied by an increase in dopamine and serotonin excretion and a significant increase in CSF concentrations of HVA and 5-HIAA.(ABSTRACT TRUNCATED AT 250 WORDS)

Central Nervous System↗
PubMed1986

Impairment of cerebral blood flow autoregulation in the newborn lamb by hypoxia.

Autoregulation of cerebral blood flow has been demonstrated in both fetal and newborn animal models under normoxic conditions. In the present experiments we have attempted to define the minimal hypoxic insult which impairs autoregulation in the newborn lamb and to assess the time to recovery. We measured cerebral blood flow by the intracarotid 133Xe method in fifteen 4- to 9-day-old lambs and tested autoregulation of cerebral blood flow by increasing blood pressure 20-30% with phenylephrine. Autoregulation was tested in the control state and at successive time intervals after an hypoxic stress (PaO2 of 30 mm Hg) of 10 or 20 min. We found that cerebral autoregulation was abolished after 20 min of hypoxia and recovered within 7 h. Since this model identifies the minimal hypoxic insult to abolish autoregulation it might be used to study means to protect autoregulation or to hasten its recovery after hypoxia.

Animals↗
PubMed1985

Sleep-waking shifts and cerebral blood flow in stable preterm infants.

Cerebral blood flow was estimated on 60 occasions in 15 well infants, 29-34 wk of gestational age, 5-17 days after birth, using 133-Xenon clearance after intravenous injection. The sleep state of the infants was determined by biparietal electroencephalography, clinical observation, and tracings of heart rate and respiration. Blood flow was 22% higher in the 11 estimations made during wakefulness, when compared to the 17 estimations made during quiet sleep. There was no difference between blood flow in active and quiet sleep. Also there was no difference between blood flow during periods of trace alternant and blood flow during periods of continuous electroencephalographic activity. It is suggested that flow-metabolism coupling is present in stable, preterm infants. The absence of an increase in cerebral blood flow during active sleep as compared with quiet sleep suggests that the neurophysiologic and neurometabolic mechanisms of rapid eye movement sleep are not yet fully developed in preterm infants.

Brain↗