Estimation of pulmonary deposition of aerosol using gamma scintigraphy

Following delivery of technetium 99m-labeled aerosols through a ventilator circuit, the amount of radioactivity in the lungs of 58 ventilated rabbits was estimated first by gamma scintigraphy via gamma camera and later by direct counting of the excised lungs (n = 116 specimens) with a gamma counter. The in situ radioactivity measured via scintigraphy was closely correlated with the gamma counter ex vivo tissue counts of the radioactivity (R2 = 0.997, P < 0.001). Overall, gamma scintigraphy gave slightly lower values of activity than the tissue counts from the gamma counter, but the limits of agreement between the two measurements were narrow enough for us to consider that the tissue and scintigraphy methods were in agreement. We conclude that gamma scintigraphy provides a convenient and noninvasive means for the accurate estimation of aerosol deposition in the lungs of small animals and possibly in small infants.

Zellweger syndrome in Saudi Arabia and its distinct features

Clinical and laboratory findings of Zellweger syndrome (ZS) patients diagnosed at King Faisal Specialist Hospital and Research Center (KFSH & RC), Riyadh, Saudi Arabia over a period of 10 years are presented in this report. Eleven patients (nine females and two males) from 2 to 4 months old were referred to KFSH & RC for evaluation of hypotonia, seizures, and dysmorphic features. The common clinical findings included high forehead, large fontanelle, shallow orbit ridges, micrognathia, upslanting palebral fissures, epicanthal folds, severe hypotonia, hyporeflexia, pigmentary retinopathy, optic nerve atrophy, complete or partial agenesis of corpus callusum, and failure to thrive. We did not observe any Brushfield spots, any renal and brain cysts, or adrenal insufficiency. Some unique clinical findings were the presence of gallstones, club feet, or bilateral knee or hip dislocation in some patients. All patients had markedly elevated plasma levels of very long chain fatty acids (VLCFA). Electron microscopy performed on liver biopsies of two patients revealed absence of peroxisomes. Biochemical studies of dermal fibroblasts from three patients showed deficient beta-oxidation of lignoceric acid and dihydroxyacetone phosphate acyltransferase (DHAPATase) activity. The tribal living in Saudi Arabia and our observation that 10 of the 11 parents in this study were first-degree relatives and, except for families 1 and 3, each family had at least another baby who died of the same disease. This suggests that the incidence of ZS in Saudi Arabia may actually be higher than our experience at KFSH & RC.

Lipoprotein A profiles in Arab newborns

BACKGROUND

Lipoprotein A (LpA) is an intriguing lipoprotein with unquestionable genetic determination which is expressed early in life. The increasing interest in LpA is due to its established recognition as an important independent risk factor for premature atherosclerosis in cardiovascular diseases. Coronary heart disease is a major cause of morbidity and premature mortality in Kuwait. The present study was designed to measure serum LpA concentrations in Arab newborns to establish reference values for LpA in newborns and its relationship to factors present in the mother and baby.

METHODS

Serum LpA concentration was analyzed in the cord blood of 107 Arab newborns by an enzyme-linked immunosorbent assay.

RESULTS

The mean and median LpA were 54.8 mg/L and 33 mg/L, respectively (range 1-500 mg/L). The frequency distribution of LpA in cord blood was skewed to the right, with the highest frequencies of LpA below 100 mg/L. Mean LpA levels were significantly higher in female infants compared with male infants at birth (77.27 +/- 108.12 mg/L vs 40.2 +/- 41.43 mg/L, P < 0.05). Lipoprotein A concentrations in newborns were not influenced by material characteristics or type of delivery. Moreover, neonatal LpA concentration did not correlate with birthweight (BW) or body mass index (BMI).

CONCLUSIONS

Lipoprotein A concentration at birth is low and is not related to maternal characteristics. Additionally, the development of circulating LpA in serum at birth was independent of BW and BMI.

Nebulisation of surfactants in an animal model of neonatal respiratory distress

AIMS

To evaluate pulmonary deposition and gas exchange following nebulisation of two surfactants by either a jet or an ultrasonic nebuliser.

METHOD

After bronchoalveolar lavage (BAL), 19 rabbits were ventilated in four groups. Group A1 (n = 5) and A2 (n = 6) received Technetium-99m labelled Exosurf, and groups B1 (n = 4) and B2 (n = 4) received radiolabelled Survanta. Groups A1 and B1 received jet nebuliser therapy, whereas groups A2 and B2 received ultrasonic nebuliser. Pulmonary deposition, distribution, and blood gases were determined.

RESULTS

Pulmonary deposition as per cent of initial dose and mg lipid) was 0.28(0.10)% or 0.59(0.21) mg in group A1, 1.05(0.23)% or 2.21(0.48) mg in group A2, 0.08(0.02)% or 0.30(0.08) mg in group B1, and 0.09(0.02)% or 0.34(0.08) mg in group B2. Deposition in group A2 was greater than in other groups (p = 0.001). Group A2 showed a small improvement in blood gases.

CONCLUSIONS

Even the highest deposition--ultrasonic nebuliser with Exosurf--achieved limited clinical effect. The aerosol route is currently not effective for surfactant treatment.

Delivery of metered dose inhaler aerosols to paralyzed and nonparalyzed rabbits

OBJECTIVE

To assess whether paralysis alters pulmonary deposition of albuterol delivered by metered dose inhaler and spacer to small animals.

DESIGN

A parallel group study of intubated and ventilated rabbits.

INTERVENTIONS

Animals in group 1 (n = 7) were paralyzed with intravenous pancuronium, and ventilated at a rate of 30 breaths/ min. The animals in group 2 (n = 6) were ventilated at a rate of 10 breaths/min under light anesthesia without paralysis. In this latter group, spontaneous respiration continued at a rate of 40 to 50 breaths/min. Both groups were maintained at PaCO2 of 35 to 40 torr (4.7 to 5.3 kPa), and other ventilatory settings were identical.

MEASUREMENTS AND MAIN RESULTS

Technetium-99m labeled albuterol aerosol was delivered by metered dose inhaler via a spacer device to both groups. Pulmonary deposition of the aerosol, determined by measuring the radioactivity in the lung tissues at autopsy, was expressed as percent of the total radioactivity dispensed by the metered dose inhaler. Group 2 showed significantly greater lung deposition than group 1 (0.510 +/- 0.076 [SEM]% vs. 0.226 +/- 0.054%, p = .0094). Deposition in the airway, the endotracheal tube, and the ventilator circuit did not differ significantly.

CONCLUSION

Metered dose inhaler delivery of aerosolized medications to ventilated rabbits is significantly enhanced if respiration is not controlled. This observation might have implications for the delivery of therapeutic aerosols to newborns and young infants receiving slow, intermittent, mandatory ventilation.