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Biomedical subjects

P Kero

Publications and source records attributed to P Kero.

At least 19 recordsLinked to original sources
PubMed1999

Responsiveness of cutaneous vasculature to thermal stimulation during phototherapy in neonatal jaundice.

The present study was performed to measure the vasoregulatory reactions to dynamic changes in local skin temperature during open bed phototherapy. Periodic thermal stimulation using warm and cool air currents was applied to the skin of ten term infants with physiological jaundice, before and during open bed phototherapy. The reactivity of skin blood flow (SBF) and heart rate was measured using laser Doppler flowmetry and power spectral analysis. The baseline SBF increased significantly by 70% (P = 0.008) during phototherapy without any significant change in skin or rectal temperature. Before phototherapy, the rhythmic (0.08 Hz) thermal skin stimulation increased the oscillations of SBF (from 89 +/- 26 au to 213 +/- 37 au, P = 0.02) at the stimulation frequency band. This response was further increased (P = 0.03) during phototherapy (from 198 +/- 54 au to 658 +/- 115 au, P = 0.004). Phototherapy increased SBF in icteric otherwise healthy neonates. The cutaneous vasodilatation augments the cardiovascular responsiveness to thermal stimulation. These results suggest that open bed phototherapy does not inhibit the cardiovascular responsiveness to local thermal skin stimulation in healthy term infants.

Heart Rate↗
PubMed1999

Mode of delivery directs the phagocyte functions of infants for the first 6 months of life.

Factors that direct the immune responsiveness of the newborn beyond the immediate post-natal period are not known. We investigated the influence of mode of delivery and type of feeding on the phagocyte activity during the first 6 months of life. Sixty-four healthy infants (34 delivered vaginally and 30 by elective Caesarean section) were studied at birth and at the ages of 2 and 6 months. Phagocyte functions were studied by measuring the chemiluminescence (CL) activity of whole blood and isolated leucocytes and by investigating the expression of phagocyte receptors (FcgammaRI (CD64), FcgammaRII (CD32), FcgammaRIII (CD16), CR1 (CD35), CR3 (CD11b) and FcalphaR (CD89)) on neutrophils, monocytes and eosinophils by using receptor-specific MoAbs and immunofluorescence flow cytometry. Infants born by elective Caesarean section had significantly higher CL activity than those delivered vaginally during the entire 6-month follow up. In addition, infants who received formula feeds had significantly higher CL activity at 6 months of age and higher expression of FcgammaRI-, Fcalpha- and CR3-receptors on neutrophils than infants exclusively breast-fed. We suggest that stress reaction associated with labour influences the phagocytic activity measured in the cord blood but later during infancy the intraluminal antigens, gut microflora and diet, become important determinants in immune programming of human individuals.

Animals↗
PubMed1999

Fecal microflora in healthy infants born by different methods of delivery: permanent changes in intestinal flora after cesarean delivery.

BACKGROUND: Newborn infants in modern maternity hospitals are subject to numerous factors that affect normal intestinal colonization--for example, cesarean delivery and antimicrobial agents. To study the duration of the effect of external factors on intestinal colonization, two groups of infants with different delivery methods were investigated. METHODS: The fecal flora of 64 healthy infants was studied prospectively. Thirty-four infants were delivered vaginally, and 30 by cesarean birth with antibiotic prophylaxis administered to their mothers before the delivery. The fecal flora was cultured on nonselective and selective media in infants 3 to 5, 10, 30, 60, and 180 days of age. Gastrointestinal signs were recorded daily by the mothers for 2 months. RESULTS: The fecal colonization of infants born by cesarean delivery was delayed. Bifidobacterium-like bacteria and Lactobacillus-like bacteria colonization rates reached the rates of vaginally delivered infants at 1 month and 10 days, respectively. Infants born by cesarean delivery were significantly less often colonized with bacteria of the Bacteroides fragilis group than were vaginally delivered infants: At 6 months the rates were 36% and 76%, respectively (p=0.009). The occurrence of gastrointestinal signs did not differ between the study groups. CONCLUSIONS: This study shows for the first time that the primary gut flora in infants born by cesarean delivery may be disturbed for up to 6 months after the birth. The clinical relevance of these changes is unknown, and even longer follow-up is needed to establish how long-lasting these alterations of the primary gut flora can be.

Antibiotic Prophylaxis↗
PubMed1999

Development of intestinal bacterial enzymes in infants--relationship to mode of delivery and type of feeding.

To evaluate the development of intestinal flora in young infants, and especially to estimate the influence of mode of delivery and type of feeding on the establishment of intestinal microflora, faecal flora was studied indirectly by measuring prospectively the faecal bacterial enzyme activities (beta-glucosidase, beta-glucuronidase and urease) in 29 full-term, healthy infants during the first 6 months of life. Mode of delivery had no influence on the faecal enzyme activities. In contrast, infants receiving formula feeds were more often urease positive at 1-2 months of age (70% vs 25%, p=0.043) and had higher median activity of beta-glucuronidase at 6 months of age (0.90 and 0.19 nmoles/mg protein x min, p= 0.0043) than exclusively breast-fed infants. Through indirect methods to measure the development of a faecal microflora our results indicate that the type of milk that infants receive during the first months of life may have an important role in the development of intestinal flora.

Breast Feeding↗
PubMed1999

Timing of peak serum cortisol values in preterm infants in low-dose and the standard ACTH tests.

The low-dose ACTH test seems to reveal mild cases of adrenal insufficiency and is beginning to be preferred over the standard ACTH test in the evaluation of adrenal suppression both in infants and in adults. The concentration-time profile of plasma cortisol in infants after a low ACTH dose is obscure. In this crossover study, we compared timing of the peak values in the low-dose and the standard ACTH stimulation tests in preterm and full-term infants. We performed the standard ACTH tests (250 microg/1.73 m2) and the low-dose ACTH tests (1 microg/1.73 m2) on 10 infants (26-40 wk gestational age) and measured serum cortisol concentration at 0, 30, 40, 60, and 120 min by RIA. Nine of the infants had received postnatal glucocorticoid treatment, and most of them had also been treated with dexamethasone antenatally. In the low-dose test, the peak values occurred at 30 or 40 min in 9/10 patients. In the standard-dose test, the peak values occurred at 60 or 120 min in 8/10 patients. These results are comparable with those from adults. According to this study, blood samples for the low-dose ACTH test in infants should be taken before dosing and between 30 and 40 min after dosing.

Adult↗
PubMed1999

Cerebral magnetic resonance imaging and ultrasonography findings after neonatal hypoglycemia.

OBJECTIVE: The aim of this study was to investigate sequential neuroradiologic changes in the brains of infants after transient neonatal hypoglycemia. We used magnetic resonance imaging (MRI) and ultrasonography (US) head scans. METHODS: Eighteen symptomatic full-term infants whose serum glucose concentrations were </=45 mg/dL (2.5 mmol/L) without any other diseases were included in the hypoglycemic group. MRI and US head scans were performed at full-term age and at the age of 2 months. The imaging results were compared with the findings of MRI and US scans in 19 healthy normoglycemic term newborn infants at the respective ages. The neurologic outcome was followed in the both groups. RESULTS: MRI or US showed evidence of abnormality in 39% the hypoglycemic infants. MRI detected more abnormalities in the brains than US. Four infants showed patchy hyperintensity lesions either in the occipital periventicular white matter or the thalamus on T1-weighted images. These lesions had a good tendency to recover and only 1 of these infants appeared to be neurologically affected. Of the 19 controls, 10% (2 of 19) had caudothalamic cysts, which were detected both with MRI and US. The relative risk of the hypoglycemic child compared with nonhypoglycemic child, to have any abnormality detected in the brain, was 3.7, with a 90% confidence interval from 1.11 to 12.28. CONCLUSIONS: Postnatal full-term MRI and US scans showed abnormalities four times more often after transient neonatal hypoglycemia than in the healthy control group. However, most often lesions were absent 2 months later. The clinical relevance of these abnormal findings remains to be clarified with detailed neurologic examinations and follow-up.

Brain↗
PubMed1998

Differences in respiratory metabolism during treatment of hypoglycemia in infants of diabetic mothers and small-for-gestational-age infants.

We investigated oxygen consumption and carbon dioxide production during treatment of hypoglycemia in infants of diabetic mothers (IDM) (n=11) and small-for-gestational-age (SGA) infants (n=6). Healthy newborn infants served as controls (n=16). The infants in both groups received normal enteral feedings and they were treated with intravenous glucose at a rate adjusted to increase plasma glucose concentration above 45 mg/dL. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured using indirect calorimetry and respiratory quotient (RQ) was calculated. Measurements were performed immediately after the correction of hypoglycemia (6-10 hr), and 24, 72, and 120 hr later. After initiation of treatment, and 24 hr later mean VCO2 and RQ were significantly higher in the IDM and the SGA infants than in healthy infants. 72 and 120 hr after the first measurement, the IDM did not differ from the healthy controls, whereas in the SGA infants mean VCO2 and VO2 were still significantly increased. In the SGA infants, the hypermetabolism was sustained during whole study period. Our results indicate that the metabolic defect resulting in hypoglycemia is different between the SGA and IDM infants. However, the treatment with supplemental glucose is necessary to both groups.

Calorimetry, Indirect↗
PubMed1998

Endothelin-1, atrial natriuretic peptide and pathophysiology of pulmonary hypertension in porcine meconium aspiration.

To evaluate the role of endothelin-1 (ET-1) and atrial natriuretic peptide (ANP) in the development of meconium aspiration-induced pulmonary hypertension, plasma ET-1 and ANP levels were measured serially for 6h after meconium instillation in juvenile pigs. Eleven 10-week-old, anaesthetized and catheterized pigs received intratracheally a bolus of 3 ml kg(-1) 20% human meconium, and five of them were premedicated with 30 mg kg(-1) methylprednisolone i.v. Another six pigs served as controls and were given 3 ml kg(-1) sterile saline intratracheally. Meconium instillation resulted in an increase in plasma ET-1 levels with a significant correlation to the simultaneously increasing PVR (r = 0.72). Methylprednisolone had no effect on the early (0-1 h) ET-1 increase, but prevented significantly the second phase (1-6 h) rise with a concomitant attenuation of the progressive pulmonary hypertension. ANP concentrations were higher in the meconium than in the control group throughout the study and further increased after steroid treatment with a good correlation to ET-1 (r = 0.86). Thus, the postinjury rise in circulating vasoactive peptides, together with the pulmonary hypertensive response, and modulation of the peptide balance and pressor reaction by steroids, suggest a contributory role for ET-1 and ANP in the development of pulmonary hypertension after meconium aspiration.

Animals↗
PubMed1998

Antenatal dexamethasone treatment decreases plasma catecholamine levels in preterm infants.

Antenatal corticosteroid therapy (ACT) has many beneficial effects on preterm infants. The cellular mechanisms of action of ACT include beta-adrenergic receptor-mediated cAMP generation. This study investigated the effects of ACT on sympathoadrenal mechanisms during immediate postnatal adaptation of preterm infants. Plasma epinephrine, norepinephrine, 3,4-dihydroxyphenylglycol, and cAMP were measured within 12 h after birth in 103 preterm infants (gestational age 24-36 wk), who were divided into two groups (non-ACT and ACT group) according to whether the mother had received dexamethasone treatment. Infants in the ACT group had significantly lower concentrations of plasma catecholamines than infants in the non-ACT group; plasma epinephrine was 38% lower, and plasma norepinephrine was 20-40% lower in the ACT group, depending on gestational age (r = -0.37 in the non-ACT group and r = -0.28 in the ACT group, p < 0.05). Plasma cAMP concentrations were similar in the two groups. Antihypertensive treatment of the mother was associated with low plasma cAMP (p < 0.001), whereas tocolytic treatment was associated with high plasma cAMP (p = 0.001) of the infant. The results indicate that ACT attenuates the birth-related increase in plasma catecholamines. Still, plasma cAMP levels remain high, which suggests enhanced beta-adrenoceptor signaling after ACT.

Antihypertensive Agents↗
PubMed1997

Cerebral metabolic rate for glucose after neonatal hypoglycaemia.

OBJECTIVE: We studied the effect of neonatal hypoglycaemia on the local cerebral metabolic rate for glucose (LCMRglc). MATERIALS AND METHODS: Eight newborn infants with neonatal hypoglycaemia were studied. The LCMRglc in the whole brain, in five cerebral regions and in skeletal muscles were quantitated using positron emission tomography (PET) and 2-[18F]Fluoro-2-deoxy-D-glucose (FDG). The PET studies were performed at the age of 5.3 +/- 6.2 days during normoglycaemia. The LCMRglc of these infants were compared to the age-adjusted LCMRglc of eight infants with suspected hypoxic-ischaemic brain injury but with normal neurological development. RESULTS: After neonatal hypoglycaemia the age-adjusted LCMRglc in the whole brain was not lower than LCMRglc of the control infants (5.33 +/- 0.60 mumol/100 g/min vs. 6.71 +/- 0.60 mumol/100 g/min). Also the metabolic rate for glucose (MRglc) in the skeletal muscles was similar in hypoglycaemic and control infants (5.56 +/- 2.48 mumol/100 g/min vs. 6.99 +/- 2.41 mumol/100 g/min). CONCLUSION: MRglc in brain and in skeletal muscle seems to be normal after neonatal hypoglycaemia, although larger group of patients with more severe hypoglycaemia are needed to confirm this finding.

Animals↗
PubMed1997

Meconium aspiration induces ARDS-like pulmonary response in lungs of ten-week-old pigs.

To investigate whether aspiration of meconium induces a hemodynamic and histologic pulmonary response similar to that frequently seen in experimental acute respiratory distress syndrome, twelve 10-week-old pigs with postnatally adapted lungs were studied. Six 10-week-old pigs received 3 ml/kg 20% human meconium via the endotracheal tube. Six control pigs of the same age were given sterile saline. Ventilator settings were adjusted to keep PaO2 above 8 kPa and PaCO2 below 5 kPa. The pulmonary hemodynamic response to aspiration consisted of two separate hypertensive components. An initial peak in pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) was followed by a progressive increase in PAP and PVR in the meconium group, whereas in the saline group these parameters returned to baseline levels. The distribution of PVR, determined by pulmonary artery occlusion, was characterized by an increase in the postarterial resistance immediately after meconium aspiration and a progressive increase in both arterial and postarterial resistance during the later phase. On histological examination, marked neutrophil sequestration was seen in the meconium lungs. In addition, lung edema formation was significantly enhanced in the meconium group, as shown by an increased lung wet/dry weight ratio. Thus, meconium aspiration resulted in a biphasic pulmonary pressor response and severe pulmonary inflammation. This response resembled that of models of experimental acute respiratory distress syndrome following diverse types of precipitating insults; this suggests that similar pathophysiologic mechanisms are elicited and cause similar pulmonary dysfunction following different forms of lung injury.

Animals↗
PubMed1997

Faecal fatty acids and gastrointestinal upset in newborn infants.

Patterns of long-chain faecal fatty acids were studied by gas-liquid chromatography in 55 newborn infants in a neonatal intensive care unit. Decreased fractions of fatty acid C16:1 and increased fractions of C16:0 and C17:0 were associated with the occurrence of abdominal distension. Decreased fractions of C16:1 and C18:2 were associated with diarrhoea. Flatulence was found in infants who had relatively smaller amounts of fatty acids C17:0D and C15:0 in their faecal samples. The differences in the patterns of faecal fatty acids are due to differences in bacterial flora. The results support the hypothesis that the initial intestinal colonization plays a role in the later gastrointestinal signs of newborn infants.

Diarrhea↗
PubMed1997

Reactivity of skin blood flow and heart rate to external thermal stimulation in anencephaly.

Oscillations of skin blood flow and heart rate can be synchronised using external rhythmic thermal stimulation in healthy adults and infants. We examined the effect of thermal stimulation on the cutaneous circulation and heart rate of an anencephalic neonate using cutaneous laser Doppler flowmetry and ECG monitoring. The results suggest that synchronisation of SBF and HR to thermal stimulation can also be induced in an anencephalic newborn.

Anencephaly↗
PubMed1997

Methylprednisolone attenuates the pulmonary hypertensive response in porcine meconium aspiration.

Severe neonatal aspiration of meconium is frequently complicated by fatal pulmonary hypertension. The protective effect of an i.v. bolus of methylprednisolone on meconium aspiration-induced hypertensive lung injury was studied in anesthetized pigs with adapted lung circulation. Eleven 10-wk-old pigs received 3 mL/kg 20% human meconium via the endotracheal tube. Five of them were pretreated with 30 mg/kg methylprednisolone 30 min before aspiration. Ventilator settings were adjusted to keep arterial PO2 above 8 kPa and arterial PCO2 below 5 kPa. Meconium insufflation induced a biphasic pulmonary pressor response during the 6 h follow-up. Methylprednisolone tended to prevent the early (0-1 h) increase in pulmonary artery pressure and inhibited significantly the second phase (1-6 h) progressive rise in pulmonary artery pressure and pulmonary vascular resistance. This inhibition of resistance increase was most profound in the postarterial segment of the lung circulation, as determined by pulmonary artery occlusion. Additionally, the methylprednisolone pretreated group demonstrated a significant decrease in venous admixture together with improved oxygenation during the late phase after the insult, and further showed evidence of diminished lung edema formation. Although meconium aspiration-induced fall in blood leukocyte concentration was inhibited by methylprednisolone pretreatment, no histologic difference was found in pulmonary leukocyte sequestration. Our results thus show that in adapted porcine lungs methylprednisolone pretreatment improves oxygenation and attenuates the meconium aspiration-induced pulmonary hypertensive response by preventing the increase in the postarterial resistance.

Animals↗
PubMed1996

Reactivity of skin blood flow and heart rate to thermal stimulation in infants during the first postnatal days and after a two-month follow-up.

The reactivity of skin blood flow and heart rate to periodic thermal stimulation was studied in 10 term small-for-gestational age (SGA) infants, in 9 preterm and 8 term normal-sized infants during the first two postnatal months. During the first postnatal days, the increase in thermally stimulated skin blood flow oscillations was absent in SGA infants but was clearly present in both preterm (p < 0.01) and term (p < 0.01) normal-sized infants. The responsiveness of SGA infants improved during the follow-up (p < 0.05). The response of the periodic heart rate variability of SGA and preterm infants was inferior to term normal-sized infants until the age of 2 months. The cardiovascular responsiveness of growth-retarded infants seems abnormal during the first days of life, and may impair their ability to meet stress, e.g. changes of ambient temperature.

Age Factors↗