PubMed Health⌕ Search

Biomedical subjects

S Andronikou

Publications and source records attributed to S Andronikou.

46 records · Page 3Linked to original sources
PubMed1987

Time-dependent effect of hypoxia on carotid body chemosensory function.

The time-dependent effects of hypoxia on the discharge rate carotid chemoreceptors were measured in anesthetized cats. Hypoxic exposure of two different durations were used: a short-term exposure (2-3 h) was used to measure the response of the same carotid chemoreceptors; and a long-term exposure (28 days at inspired PO2 of 70 Torr) to study carotid chemoreceptor properties in one group of cats relative to those of a control group. In the chronically hypoxic and control groups, determinations were made of the 1) steady-state responses to four levels of arterial PO2 (PaO2) at constant levels of arterial PCO2; 2) steady-state responses to acute hypercapnia during hyperoxia; and 3) maximal discharge rates during anoxia. We found that the acute responses of carotid chemoreceptor afferents to a given level of hypoxia (PaO2 = 30-40 Torr) did not significantly change within 2-3 h. After long-term exposure the carotid chemoreceptor responses to hypoxia significantly increased, with no significant changes in the hypercapnic response and in the maximal discharge rate during anoxia. We conclude that isocapnic hypoxia may not elicit a sufficient cellular response within 2-3 h in the cat carotid body to sensitize the O2 responsive mechanism, but hypoxia of longer duration will sensitize such a mechanism, thereby augmenting the chemosensory activity.

Acid-Base Equilibrium↗
PubMed1987

Differential effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 in the cat.

Effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 were investigated using an in situ perfusion technique. Cats were anesthetized, paralyzed, and artificially ventilated. To avoid a possible reaction between an oligomycin-ethanol mixture and blood, we administered oligomycin to the carotid body via cell- and protein-free perfusate. Except for the perfusion periods, the carotid body received its own natural blood supply. Responses to O2, CO2, sodium cyanide, and nicotine of the same carotid chemoreceptor afferents were studied before and after each perfusion. An appropriate low dose of oligomycin completely blocked carotid chemoreceptor response to O2 while preserving the CO2 response. At the same time cyanide response was attenuated leaving nicotine response intact. Additional doses of oligomycin attenuated carotid chemoreceptor response to CO2 as well. Perfusion with a blank solution containing ethanol did not change the carotid body chemoreceptor responses. These effects of oligomycin on carotid chemoreceptor responses to O2 and CO2 were reversible, and restoration of the response to CO2 preceded that to O2. In addition, oligomycin administered into the blood with close intra-arterial injection produced similar differential blockade of O2 and CO2 chemoreception, preserving the nicotine and dopamine effects. This study confirmed the previous findings and provided new evidence showing that 1) the responses of carotid chemoreceptor to O2 and CO2 were separable by oligomycin due to the inhibition of oxidative phosphorylation and 2) the responses to nicotine and dopamine were intact even after blockade of O2 response.

Animals↗
PubMed1987

Parenteral nutrition effect on serum insulin in the preterm infant.

Blood glucose and serum insulin levels were measured in two groups of preterm infants that had been matched for gestational age. Both groups were fed parenterally during the first 72 hours of life and were mechanically ventilated because of respiratory distress syndrome. Group A infants (n = 11) received 10% glucose (infusion rate 5 mg/kg/min) and group B infants (n = 12) received amino acid solution (1.2 g/kg/d) in addition to 10% glucose at the same rate as those in group A. Infants in both groups received 90 mL/kg of fluid per day. There was no difference in blood glucose or serum insulin levels between the two groups 24 hours after beginning the infusion; however, at 48 hours there was a significantly (P less than .01) higher insulin level in infants receiving amino acid and glucose infusion compared with those receiving only glucose. Blood glucose level remained stable in both groups. We conclude that, in the stable preterm infant, the higher insulin level associated with continuous amino acid infusion does not result in hypoglycemia.

Amino Acids↗
PubMed1984

Effect of tobramycin on fractional sodium excretion in neonates.

Fractional sodium excretion (FENa) was measured in 25 neonates during and after treatment with tobramycin. Mean birthweight of infants was 1.83 kg and mean gestational age was 34.3 weeks. Tobramycin therapy was initiated within 48 hours of birth and levels were maintained within the therapeutic range. Mean FENa values were persistently elevated during treatment and decreased to the normal range within 2 days of stopping antibiotics. Blood urea and creatinine concentrations were normal throughout the period of study. Exposure to the aminoglycoside appears to delay the previously described postnatal decline in FENa, most likely reflecting subtle renal tubular dysfunction.

Aminoglycosides↗
PubMed1983

Early introduction of parenteral nutrition in premature infants and its effect on calcium and phosphate homeostasis.

Calcium and phosphate homeostasis was evaluated in two matched groups of sick premature neonates. Parenteral nutrition in the form of an amino acid solution was administered to 10 infants (group A), and a dextrose-electrolyte-calcium solution was administered to 11 infants (group B). The infants did not demonstrate the immediate phosphaturia previously described following infusion of amino acids and/or glucose. In both groups, phosphate excretion was directly related to phosphate intake (r = 0,45; P less than 0,001). In group A infants infusion of the amino acid solution was associated with a significantly greater fall in serum calcium levels on the 2nd day of life (P = 0,02 v. group B), despite similar intake and excretion of calcium in the two groups. We suggest that the phosphate content of the amino acid solution may aggravate the neonate's tendency to hypocalcaemia, although frank hyperphosphataemia was not observed.

Calcium↗
PubMed1982

Congo-Crimean haemorrhagic fever in South Africa. Report of a fatal case in the Transvaal.

A 13-year-old boy, after having spent a week at a camp in a nature reserve in the western Transvaal, developed an acute illness of sudden onset characterized by chills, severe headache, muscle pains and high fever. On the 3rd day he developed a haemorrhagic state with profuse bleeding from the gastro-intestinal tract and other mucous membranes and petechial haemorrhages into the skin, from which he died on the 6th day after onset of the illness. A tick, identified as a species of Hyalomma, was found attached to his scalp. The provisional clinical diagnosis of Congo virus fever was confirmed in the laboratory by the isolation of the virus in newborn mice inoculated with the patient's blood. This is the first incrimination of Congo virus as the cause of a fatal case of haemorrhagic fever in South Africa, although it is known to occur in several countries in the tropical region of Africa and in south-eastern Europe and Asia.

Adolescent↗
PubMed1982

Effect of a new neonatal maintenance solution on potassium, calcium and phosphate homeostasis in sick neonates.

A new neonatal maintenance solution (Neonatalyte; Sabax) was administered to 12 newborn infants with respiratory distress. Under closely controlled conditions, the infusion was commenced at a mean age of 12 +/- 10 hours. The mean serum potassium level increased from 4,6 +/- 0,6 mmol/l to 5,6 +/- 1,4 mmol/l (P less than 0,02), while in 5 infants (42%) hyperkalaemia (greater than or equal to 6,5 mmol/l) occurred within 8 hours of commencement of Neonatalyte infusion. The mean serum calcium level decreased from 2,1 mmol/l on day 1 to 1,7 mmol/l on day 2 (P less than 0,001) and was 1,8 mmol/l on day 3 (P less than 0,01), despite mean calcium intakes of 18,33 and 45 mg on days 1, 2 and 3 respectively. The early hypocalcaemia may be related to the phosphate content of Neonatalyte. We conclude that Neonatalyte is not an ideal solution for sick newborn infants who cannot be fed orally for the first few days of life.

Calcium↗
PubMed1982

Transient neonatal hyperammonaemia. A case report.

A case of transient neonatal hyperammonaemia (TNH) is described. The entity of TNH has only recently been identified and awareness of the condition may reveal that it is, in fact, not exceedingly rare in premature infants. The presentation of TNH mimics the neurological damage associated with asphyxia, sepsis or intraventricular haemorrhage, all of which occur frequently in premature infants. However, while the latter conditions are associated with a poor prognosis, the outcome for infants with TNH appears to be favourable if aggressive treatment is instituted at an early stage. Treatment consists of dialysis and/or exchange transfusion. A brief review of the literature on TNH is included.

Ammonia↗
PubMedDate not supplied

Clinical significance of creatine kinase isoenzymes for fetal asphyxia in women at labor.

Creatine kinase-brain isoenzyme activity (CK-BB) was measured longitudinally in the serum of 31 pregnant women in the first stage of labor (early and advanced), at delivery, and 1, 6 and 24 h after delivery, in the umbilical cord and in the serum of their neonates on the first day of life. There was no increase in serum CK-BB values of mothers that delivered normally (n = 15) or had an elective cesarean section (n = 5). Pregnant women with signs of fetal distress had an increase in CK-BB levels in the first stage of labor (mean +/- SD 4.5 +/- 4.9 U/l, p < 0.03) and 6 h after delivery (12 +/- 4 U/l, p < 0.0001). Neonates with intrauterine stress also had an increase in their CK-BB to 144 +/- 116 U/l at 6 h of life, in comparison with babies born without signs of stress. It appears that CK-BB during labor and in the first hours of life may be indicative of intrauterine stress.

Asphyxia Neonatorum↗