Tetsuro Fujiwara

Proteolipid in bovine lung surfactant: Its role in surfactant function

The chemical and biophysical properties of the proteins in the lipid extracts of lung surfactant have not clearly been determined. These proteins were isolated from lung surfactant lipids by Sephadex LH-20 chromatography and purified with silicic acid chromatography followed by dialysis against organic solvents. The proteolipid thus obtained had a protein to phospholipid ratio of 3 to 1 (w/w). The proteolipid apoprotein had a nominal molecular weight of ca. 5 kDa. We evaluated the functional role of this proteolipid by combining it with proteolipid-depleted surfactant lipids or synthetic dipalmitoylphosphatidylcholine (DPPC) and then measuring with a pulsating bubble surfactometer. The proteolipid and DPPC recombinant reproduced the surface activity of natural lung surfactant. We conclude that this 5 kDa proteolipid apoprotein is a functionally important constituent of lung surfactant.

Acute disseminated demyelination due to primary human herpesvirus-6 infection

AbstractA previously healthy 19-month-old boy developed acute encephalopathy, thrombocytopenia and hepatic dysfunction. Human herpesvirus-6 (HHV-6) DNA was found in his CSF during the acute stage of the disease by means of the polymerase chain reaction. T2-weighted MRI revealed high signal intensity in the left thalamus and left parieto-occipital deep white matter. The myelin basic protein concentration in the CSF was elevated suggesting acute demyelination. The patient is now 2.5 years old and has no sequelae. Conclusion Since clinical course and neuroimaging after HHV-6 infection are similar to those in acute disseminated encephalomyelitis, clinicians must pay attention to primary HHV-6 infection in patients under 2 years old with white matter lesions.

Stable microbubble test for predicting the risk of respiratory distress syndrome: II. Prospective evaluation of the test on amniotic fluid and gastric aspirate

We determined prospectively if the stable microbubble (SM) test on gastric aspirate obtained at birth was as useful as that on amniotic fluid in predicting respiratory distress syndrome (RDS). One hundred and five paired samples of amniotic fluid obtained at delivery from 105 consecutive women with gestation of 35 weeks or less and gastric aspirates from their neonates obtained within 30 min of birth were studied. The SM test with the predefined cut-off value of less than 5 bubbles/mm2 for amniotic fluid and less than 10 bubbles/mm2 for gastric aspirate signified the risk of RDS with the positive predictive value of 100% and 96% and with the negative predictive value of 91% and 84%, respectively. We conclude that the SM test on both amniotic fluid and gastric aspirate obtained at birth is a rapid (<10 min), simple and reliable procedure for predicting neonates who will develop RDS. It may be used as a bedside test to define a population of neonates with surfactant deficiency in clinical trials of prophylactic surfactant therapy.

A prospective, randomized trial of early versus late administration of a single dose of surfactant-TA

Thirty-two neonates weighing 500-1500 g with documented surfactant deficiency and without evidence of severe birth asphyxia, infection, prolonged rupture of membranes greater than or equal to 72 h, or oligohydramnios were randomly assigned to receive a single intratracheal dose of surfactant-TA (100 mg/kg) either within 30 min of birth (n = 16, early group) or at 6 h of age (n = 16, late group). By 6 h of age, all neonates of the late group had moderate/severe RDS, while none of the neonates of the early group had either clinical or radiological respiratory distress syndrome. The incidence of bronchopulmonary dysplasia was significantly lower in survivors of the early group than those of the late group (1/15 versus 7/14, a 43% reduction with a 95% confidence interval of 14-72%, P = 0.025). These beneficial effects of early surfactant treatment remained after controlling for the various confounding factors in the logistic models.

Surfactant Replacement Therapy in Premature Babies with Respiratory Distress Syndrome: Factors Affecting the Response to Surfactant and Comparison of Outcome from 1982–86 and 1987–91

The impact of surfactant therapy on chronic lung disease remains uncertain. During the past decade (1982–91), over 300 babies with respiratory distress syndrome (RDS) weighing 501–2,500 g at birth were consecutively treated with surfactant‐TA at our neonatal intensive care unit. Data on 95 RDS babies treated in the first 5 year period (Period 1, 1982–86) were compared with those on 158 RDS babies treated in the second 5 year period (Period 2, 1987–91). Overall respiratory improvement was better in Period 2 than in Period 1. In Period 2, surfactant therapy converted 98% of the babies with moderate/severe RDS to those with ‘near normal’ lung by 72 hr post‐treatment. In Period 2, 95% of the surfactant‐treated babies weighing 501–1,750 g at birth survived, 97% of which required no supplemental oxygen at 40 weeks corrected gestational age. Increased survival rate in the surfactant‐treated babies during the past decade has not been followed by a parallel increase in chronic lung disease. The severity of the initial pulmonary disease per se was not the significant risk factor for chronic lung disease. Several other variables affecting the response to surfactant therapy and outcome have been identified by stepwise logistic regression analysis and include factors related to perinatal events such as birth asphyxia and infection, and other complications of prematurity.

Biophysical properties of protein‐free, totally synthetic pulmonary surfactants, ALEC and Exosurf, in comparison with surfactant TA

An artificial pulmonary surfactant prepared from chloroform‐methanol extract of bovine pulmonary surfactant (surfactant TA) has been shown to be effective in both the prevention and the treatment of respiratory distress syndrome in premature babies. Recently, two types of protein‐free totally synthetic surfactants, artificial lung expanding compound (ALEC) and Exosurf, have been evaluated in clinical trials of surfactant therapy. Artificial lung expanding compound was used initially as a dry powder, but is now prepared as a crystalline suspension in saline at 4°C. In this study we compared the biophysical properties of three different forms of ALEC (dry powder, crystalline suspension at 4°C and 37°C), Exosurf and surfactant TA (Surfacten) using a modified Wilhelmy surface balance and a pulsating bubble surfactometer. Surface activity of a crystalline suspension of ALEC in cold saline was no better than the dry powder of ALEC. Surfactant activity of ALEC was improved by addition of hydrophobic surfactant protein B and C (SP‐B, SP‐C) which are important constituents of surfactant TA. Surface properties of ALEC in any form and Exosurf were not superior to those of surfactant TA. These results suggest that a surfactant which contains SP‐B and SP‐C does not necessarily have to be dry or crystalline for an effective exogenous surfactant.

Precision and Reliability of Stable Microbubble Test as a Predictor of Respiratory Distress Syndrome

The precision and reliability of the stable microbubble test as a predictor of respiratory distress syndrome (RDS) were studied. In blind experiments, the stable microbubble test was performed by three analysts in quadruplicate on six different amniotic fluid samples obtained from pregnant women whose babies developed RDS and on three samples prepared from mature controls. Three‐way analysis of variance revealed that there were statistically significant differential effects of the analyst, observer, and sampling on the stable microbubble values, and also that there were statistically significant interactions between the analyst and observer as well as between the analyst and sampling. However, the magnitude of these effects was not large enough to modify the interpretation of the test results. We conclude that the rapidity, simplicity and reliability of the stable microbubble test allow for its use as a bedside procedure in identifying infants who are likely to develop RDS.

A case of infantile spasms: Epileptic apnea as partial seizures at onset

We report a 2-month-old boy who presented with apneic attacks as a manifestation of epileptic seizures at onset and eventually progressed to infantile spasms. At onset, at 2 months of age, apneic attacks were the sole symptom of epileptic fits. Although these seizures were accompanied by cyanosis, bradycardia was not noted. An ictal electroencephalogram showed focal paroxysmal discharges in the temporal area. Treatment with sodium valproate was not effective to control his seizures. By 6 months of age, he progressed to infantile spasms. Although his seizures could be completely controlled with the use of zonisamide, vitamin B6 or high-dose immunoglobulin, his mental and behavioral development was retarded severely. There have been no previously published cases with infantile spasms that evolved from epileptic apnea as partial seizures.

Surfactant proteins and stable microbubbles in tracheal aspirates of infants with respiratory distress syndrome: relation to the degree of respiratory failure and response to exogenous surfactant.

Abstract Surfactant proteins (SP-A and SP-BC), albumin (ALB), and stable microbubble (SM) count were measured in tracheal aspirates from infants with respiratory distress syndrome (RDS) receiving single-dose Surfactant-TA (surfactant group, n = 32) or no surfactant (control group, n = 12), and those without RDS (non-RDS group, n = 8) to determine biochemical and biophysical status of surfactant in the course of RDS after surfactant replacement. Surfactant therapy resulted in immediate and sustained elevations of SP-BC/ALB and SM count with a rapid fall in ventilatory index to levels measured in the non-RDS group, whereas these indices improved slowly in the control group. The SP-A/ALB was initially low in both RDS groups and increased to levels measured in the non-RDS group by age 48 h. Multiple regression analysis showed that SP-BC/ALB, postnatal age, SM count, SM count/SP-A plus SP-BC, and surfactant therapy were independently associated with the severity of RDS as assessed by ventilatory index (r = 0.75, P < 0.0001; number of samples = 256). Infants with a relapse response to surfactant (n = 9) had levels of SP-A/ALB and SP-BC/ALB similar to those measured in the sustained group (n = 23), but had significantly lower SM count and SM count/SP-A plus SP-BC between 24 and 96 h of age. Conclusion Surfactant therapy normalizes the sur factant and respiratory status of infants with RDS. Surfactant dysfunction rather than depletion may explain the relapse response seen in some surfactant recipients.

Ethanol resistive microbubble test: A modification of the stable microbubble test used to predict respiratory distress syndrome

The stable microbubble (SM) test on gastric aspirate obtained at birth proved useful in identifying infants who would develop respiratory distress syndrome (RDS). This test involves only the count of stable microbubbles of ≤ 15 μm in diameter. Larger bubbles (> 15 μm in diameter) are not necessary for the test and may interfere with stable microbubble counting. The aims of the present study were to determine: (i) if larger bubbles could be selectively removed by adding ethanol, a potent bubble breaker; and (ii) if the predictive value of this modified test, the ethanol resistive microbubble (ERM) test, on the development of RDS was similar to that of the SM test. Varying amounts of different concentrations of ethanol‐water solutions were added to the top of the bubble crop generated by the SM test procedure, and the mean counts of stable microbubbles and larger bubbles in five regions were calculated. A volume of 10 μL of 47.5% ethanol was effective in defoaming larger bubbles generated by the SM test procedure without altering the stable microbubble counts. When concurrently performed on 43 samples of gastric aspirate obtained at birth from infants of less than 35 weeks gestation, the RDS predictive value of the ERM test was similar to that of the SM test. It was concluded that the ERM test may serve as an alternative to the SM test.