Refractory otitis media and otitis externa in a koala (Phascolarctos cinereus) treated with total ear canal ablation and lateral bulla osteotomy.

BACKGROUND: To the authors' knowledge, this is the first report fully describing the surgical and medical management of otitis media and otitis externa in the koala (Phascolarctos cinereus) treated by total ear canal ablation and lateral bulla osteotomy. CASE REPORT: An adult male koala captured as part of a monitoring project in South East Queensland was diagnosed with chlamydial cystitis. Purulent discharge from the right ear was also observed; diagnostic imaging was consistent with otitis media and otitis externa. Yokenella regensburgei was repeatedly cultured from the site. Clinical signs resolved with topical antibiotic therapy; however, recrudesced following cessation of antibiotics. A total ear canal ablation and lateral bulla osteotomy was performed, followed by an extended period of systemic antibiotic therapy. Mild facial nerve paresis was observed for 4 weeks postoperatively and resolved spontaneously. The koala remained clinically healthy for the 6 months it was monitored following release. CONCLUSION: Total ear canal ablation combined with lateral bulla osteotomy appears to be an appropriate surgical intervention for otitis media combined with otitis externa refractory to medical management in the koala. Transient postoperative facial nerve paresis is a possible complication, as documented in other species. To the authors' knowledge this is the first case of Yokenella regensburgei infection outside of humans and American alligators (Alligator mississippiensis); the clinical significance of this pathogen in the koala remains unknown.

Body temperature of free-ranging koalas (Phascolarctos cinereus) in south-east Queensland.

The distribution of the koala (Phascolarctos cinereus) in Queensland is predicted to contract as a result of climate change, driven by the frequency, intensity and duration of heatwaves and drought. However, little is known about the physiological responses of this species to environmental extremes under field conditions. This study aimed to establish the efficacy of surgically implanted thermal radio transmitters and data loggers to measure the body temperature of free-ranging koalas across a range of environmental conditions and ambient temperatures. Five free-ranging koalas in southeast Queensland were implanted with thermal transmitters and data loggers waxed together as a single package. Body temperatures were recorded for variable periods ranging from 3 to 12 months. Diurnal rhythms in body temperature were detected irrespective of season. The long-term diurnal body temperature peak for all koalas occurred between 16:00 and 17:00 h and body temperature was 36.7-36.9 °C, the long-term nadir occurred between 07:00 and 08:00 h and body temperature was 35.4-35.7 °C. Koala body temperatures as low as 34.2 °C and as high as 39.0 °C were recorded. Thermolability became apparent when ambient temperatures were outside the deduced thermal neutral zone for koalas (14.5-24.5 °C): heat was accumulated during the day and dissipated during the cool of the night. While this study is the first to report on body temperature of free-ranging koalas in their normal behavioural context, further investigations are necessary to determine the physiological boundaries of the thermal niche for this species, in order to better equip models that will more accurately predict the impacts of climate change on koalas.

Recording body temperature in koalas (Phascolarctos cinereus): a comparison of techniques.

OBJECTIVE: Compare the use of four techniques to measure body temperature in koalas: intraperitoneal (thermal data logger and temperature sensitive radio transmitter), rectal (certified thermometer), tympanic (infrared thermometer), and hind foot (infrared camera). METHODS: The body temperature data collected concurrently from the intraperitoneal loggers were used as the benchmark in the analyses. RESULTS: The rectal, foot and tympanic methods consistently recorded lower body temperature when compared with the benchmark. There was a strong positive relationship (R2 = 0.79) between logger and rectal measurements, but no significant relationship between logger and foot or logger and tympanic measurements. CONCLUSION: Rectal measurements can be used to record internal body temperature, with the caveat that such measurements will generally register a temperature approximately 0.25°C lower than the actual intraperitoneal temperature.

Fetal size and growth velocity in chronic hypertension.

OBJECTIVE: To investigate longitudinal fetal growth and growth velocity for commonly measured biometric parameters in women with chronic hypertension. METHODS: Two centre retrospective European study of women with chronic hypertension ascertained at pregnancy booking. Ultrasound measurements of head circumference (HC), abdominal circumference (AC) and femur length (FL) were used to derive longitudinal fetal growth charts derived using functional linear discriminant analysis (FLDA). These were compared to existing cross sectional and longitudinal charts, as was birthweight. RESULTS: 282 women with a median of 3 third trimester ultrasound examinations were included. Gestation at delivery was 37.5weeks (SD 2.68), birthweight 3049g (SD 785). Birthweight <10th percentile found in 15.6% deliveries, >90th percentile 20.2%. Fetal size curves derived from women with chronic hypertension were no different to cross sectional and longitudinal charts for a normal population. Compared to a standard longitudinal biometry chart, growth velocity (mm/day) in chronic hypertension was higher for AC and FL at 30-32weeks (AC 1.447vs 1.357 p<0.05; FL 0.296vs 0.269 p<0.01) and 34-36weeks (AC 1.325vs 1.140 p<0.01; FL 0.248vs 0.198 p<0.01). CONCLUSIONS: In women with chronic hypertension there is an excess of both SGA and LGA babies compared to population standards. Growth velocity of the AC and FL was greater after 30weeks compared to a normal population.

Assessment of florfenicol as a possible treatment for chlamydiosis in koalas (Phascolarctos cinereus).

OBJECTIVE: Because of limited availability of chloramphenicol to veterinary suppliers, a preliminary study was performed to predict whether an analogue, florfenicol, is an efficacious treatment for chlamydiosis in koalas. METHODS: Florfenicol was administered to koalas with naturally occurring chlamydiosis at 20 mg/kg SC (n = 3) and at 5 mg/kg (n = 3) and 10 mg/kg (n = 3) IV. The estimated areas under the plasma concentration versus time curves (AUC) were compared with the minimum inhibitory concentration to inhibit Chlamydia pecorum. Clinical data were also examined from field trials conducted on koalas (n = 19) with naturally occurring chlamydiosis and treated with florfenicol at a range of dosages (5-20 mg/kg SC and 6-15 mg/kg IV). Florfenicol binding to proteins in plasma was also determined. RESULTS: Florfenicol was not detectable in plasma 24 h post-administration at 20 mg/kg SC. The estimated AUC0-24 h following administration at 10 mg/kg IV suggests florfenicol might be effective against Chlamydia spp. via this route. Florfenicol binding to plasma proteins was 13.0% (± 0.30 SEM). After treatment with florfenicol in field trials, 5 of 19 koalas (26%) were released without further treatment, 4 with no long-term follow-up; 6 (32%) required additional treatment with chloramphenicol to resolve chlamydiosis; 7 (36%) failed to clinically improve, of which 3 had clinical signs and/or necropsy findings suggestive of antibiotic-related gastrointestinal dysbiosis; another koala died within minutes of florfenicol administered IV at 7 mg/kg. CONCLUSION: When administered at dosages tolerable in the field, florfenicol is a problematic treatment for chlamydiosis based on equivocal outcomes and plasma concentrations below those that inhibit the pathogen.

Trypanosomiasis in an Australian little red flying fox (Pteropus scapulatus).

CASE REPORT: An adult female Australian little red flying fox (Pteropus scapulatus) presented with icterus and anaemia. Examination of a blood smear revealed numerous trypanosomes 20.4-30.8 µm long with tapered ends. Necropsy and histological findings were consistent with trypanosome infection of lymphoid tissue and intravascular haemolysis. Sequence and phylogenetic analysis demonstrated this trypanosome species to be genetically distinct and most similar to Trypanosoma minasense and Trypanosoma rangeli (with a genetic distance of 1% at the 18S rRNA locus for both). CONCLUSION: To the authors' knowledge this is the first report of a trypanosome infection associated with clinical disease in bats.

Pneumonia due to Chlamydia pecorum in a Koala (Phascolarctos cinereus).

Chlamydiosis is a common infectious disease of koalas (Phascolarctos cinereus), but Chlamydia spp. have not yet been demonstrated to cause pneumonia in these animals. A juvenile male koala died following an episode of respiratory disease. At necropsy examination, the lung tissue was consolidated. Microscopical lesions in the lung included pyogranulomatous bronchopneumonia, proliferation of bronchiolar and alveolar epithelium and interstitial fibrosis. Hyperplastic bronchiolar epithelial cells contained aggregates of small basophilic punctate organisms, which were confirmed as chlamydiae by transmission electron microscopy and immunohistochemistry. Real-time polymerase chain reaction identified these as Chlamydia pecorum. This report provides the best evidence to date of chlamydial infection causing pneumonia in a koala, and the first evidence that C. pecorum is capable of infecting the bronchiolar epithelium of the koala.

Accuracy of nuchal translucency measurement depends on equipment used and its calibration.

OBJECTIVES: To determine the effect of different ultrasound machine-probe combinations on nuchal translucency (NT) measurements and to assess how this impacts on the accuracy of the NT-derived component of first-trimester screening for trisomy 21. METHODS: Sixteen different ultrasound machine-probe combinations were used for axial measurement of 2.0-, 3.0- and 4.0-mm spaced targets in an ultrasound phantom. Differences between the measured and known values were determined. The mean of the axial measurements was used to calculate adjusted risks for trisomy 21, given specific clinical scenarios. RESULTS: Differences observed using different machine-probe combinations for the 2.0-mm target ranged from 1.8-2.2 mm; for the 3.0-mm target, 2.7-3.2 mm; and for the 4-mm target, 3.7-4.3 mm, and exceeded those due to intraobserver variability. For a fetal crown-rump length of 50.0 mm and NT measurement of 2.0 mm, the maximum/minimum measurements in the fetus of a 40-year-old woman led to derived risks ranging from 1 in 32 (NT, 2.2 mm) to 1 in 189 (NT, 1.8 mm) and in the fetus of a 20-year-old with an NT of 3.0 mm these ranged from 1 in 102 (NT, 3.2 mm) to 1 in 160 (NT, 2.7 mm). CONCLUSIONS: We have described the effect of machine-probe combinations on small but very precise ultrasound measurements. Such machine-probe combinations led to greater variability than those ascribed to intraobserver differences, and significantly affected the screening risk for the same fixed measurement. This finding has implications for Down syndrome screening algorithms and audit of ultrasound operators. Furthermore, most ultrasound machines are neither calibrated nor specified for measurements of tenths of a mm.

The sonopartogram: a novel method for recording progress of labor by ultrasound.

OBJECTIVES: Progress of labor has hitherto been assessed by digital vaginal examination (VE). We introduce the concept of a non-intrusive ultrasound (US)-based assessment of labor progress (the 'sonopartogram') and investigate its feasibility for assessing cervical dilatation and fetal head descent and rotation. METHODS: This was a prospective study performed in 20 women in the first stage of labor in two European maternity units. Almost simultaneous assessment of cervical dilatation and fetal head descent and rotation were made by US and digital VE. RESULTS: The total number of paired US and digital VE assessments was 52, with a median of three per woman. Overall, 5% of sonopartogram parameters were not obtained compared with 18% of conventional digital VE parameters (P < 0.001). Assessment of cervical dilatation was possible in 86.5% of US examinations and 100% of digital VEs (P = 0.02), and dilatation was assessed as being greater by digital VE than by US (mean difference, 1.16 (95% limits of agreement, -0.76, 3.08) cm, r(2) = 0.68, P = 0.01). Fetal head descent was measured in all 52 cases by both methods (r(2) = 0.33, P < 0.001), but correlation between the two was only moderate. Head rotation was obtainable in 98% of US examinations and 46% of digital VEs (P < 0.001), with a mean difference of -3.9° (95% limits of agreement, -144.1°, 136.3°). CONCLUSION: In this proof-of-concept study, the acquisition of data regarding progress of labor was more successful for the sonopartogram than the conventional partogram. The agreement between digital VE and US was good for cervical dilatation and head rotation but less so for head descent. US assessment of the progress of labor is feasible in most cases.

Pharmacokinetics of meloxicam in koalas (Phascolarctos cinereus) after intravenous, subcutaneous and oral administration.

The pharmacokinetic profile of meloxicam in clinically healthy koalas (n = 15) was investigated. Single doses of meloxicam were administered intravenously (i.v.) (0.4 mg/kg; n = 5), subcutaneously (s.c.) (0.2 mg/kg; n = 1) or orally (0.2 mg/kg; n = 3), and multiple doses were administered to two groups of koalas via the oral or s.c. routes (n = 3 for both routes) with a loading dose of 0.2 mg/kg for day 1 followed by 0.1 mg/kg s.i.d for a further 3 days. Plasma meloxicam concentrations were quantified by high-performance liquid chromatography. Following i.v. administration, meloxicam exhibited a rapid clearance (CL) of 0.44 ± 0.20 (SD) L/h/kg, a volume of distribution at terminal phase (Vz ) of 0.72 ± 0.22 L/kg and a volume of distribution at steady state (Vss ) of 0.22 ± 0.12 L/kg. Median plasma terminal half-life (t(1/2)) was 1.19 h (range 0.71-1.62 h). Following oral administration either from single or repeated doses, only maximum peak plasma concentration (C(max) 0.013 ± 0.001 and 0.014 ± 0.001 µg/mL, respectively) was measurable [limit of quantitation (LOQ) >0.01 µg/mL] between 4-8 h. Oral bioavailability was negligible in koalas. Plasma protein binding of meloxicam was ~98%. Three meloxicam metabolites were detected in plasma with one identified as the 5-hydroxy methyl derivative. This study demonstrated that koalas exhibited rapid CL and extremely poor oral bioavailability compared with other eutherian species. Accordingly, the currently recommended dose regimen of meloxicam for this species appears inadequate.

Pharmacokinetics of chloramphenicol following administration of intravenous and subcutaneous chloramphenicol sodium succinate, and subcutaneous chloramphenicol, to koalas (Phascolarctos cinereus).

Clinically normal koalas (n = 19) received a single dose of intravenous (i.v.) chloramphenicol sodium succinate (SS) (25 mg/kg; n = 6), subcutaneous (s.c.) chloramphenicol SS (60 mg/kg; n = 7) or s.c. chloramphenicol base (60 mg/kg; n = 6). Serial plasma samples were collected over 24-48 h, and chloramphenicol concentrations were determined using a validated high-performance liquid chromatography assay. The median (range) apparent clearance (CL/F) and elimination half-life (t(1/2)) of chloramphenicol after i.v. chloramphenicol SS administration were 0.52 (0.35-0.99) L/h/kg and 1.13 (0.76-1.40) h, respectively. Although the area under the concentration-time curve was comparable for the two s.c. formulations, the absorption rate-limited disposition of chloramphenicol base resulted in a lower median C(max) (2.52; range 0.75-6.80 µg/mL) and longer median tmax (8.00; range 4.00-12.00 h) than chloramphenicol SS (C(max) 20.37, range 13.88-25.15 µg/mL; t(max) 1.25, range 1.00-2.00 h). When these results were compared with susceptibility data for human Chlamydia isolates, the expected efficacy of the current chloramphenicol dosing regimen used in koalas to treat chlamydiosis remains uncertain and at odds with clinical observations.

The potential impact of native Australian trypanosome infections on the health of koalas (Phascolarctos cinereus).

Whole blood collected from koalas admitted to the Australian Zoo Wildlife Hospital (AZWH), Beerwah, QLd, Australia, during late 2006-2009 was tested using trypanosome species-specific 18S rDNA PCRs designed to amplify DNA from Trypanosoma irwini, T. gilletti and T. copemani. Clinical records for each koala sampled were reviewed and age, sex, blood packed cell volume (PCV), body condition, signs of illness, blood loss, trauma, chlamydiosis, bone marrow disease, koala AIDS and hospital admission outcome ('survival'/ 'non-survival') were correlated with PCR results. Overall 73.8% (439/595) of the koalas were infected with at least 1 species of trypanosome. Trypanosoma irwini was detected in 423/595 (71.1%), T. gilletti in 128/595 (21.5%) and T. copemani in 26/595 (4.4%) of koalas. Mixed infections were detected in 125/595 (21%) with co-infections of T. irwini and T. gilletti (101/595, 17%) being most common. There was a statistical association between infection with T. gilletti with lower PCV values and body condition scores in koalas with signs of chlamydiosis, bone marrow disease or koala AIDS. No association between T. gilletti infection and any indicator of health was observed in koalas without signs of concurrent disease. This raises the possibility that T. gilletti may be potentiating other disease syndromes affecting koalas.

Commissurotomy for improving access to the oral cavity of the wombat.

Wombats are a grazing marsupial with a diet rich in silicates, which is highly abrasive and results in a higher rate of tooth attrition than in other grazing marsupials such as kangaroos. Any interference in the natural wear process, such as malocclusion or loss of teeth, causes overgrowth of teeth. The small mouth opening of the wombat makes access to the caudal mouth difficult and overgrowth of cheek teeth can be difficult to treat effectively. This case report describes a technique that greatly improves access to allow dental treatment of all overgrown teeth with minimal complications.

Multiple loci comprising immune-related genes regulate experimental neuroinflammation.

A 58 Mb region on rat chromosome 4 known to regulate experimental autoimmune encephalomyelitis (EAE) was genetically dissected. High-resolution linkage analysis in an advanced intercross line (AIL) revealed four quantitative trait loci (QTLs), Eae24-Eae27. Both Eae24 and Eae25 regulated susceptibility and severity phenotypes, whereas Eae26 regulated severity and Eae27 regulated susceptibility. Analyses of the humoral immune response revealed that the levels of serum anti-myelin oligodendrocyte glycoprotein (MOG) immunoglobin G1 (IgG1) antibodies are linked to Eae24 and anti-MOG IgG2b antibodies are linked to both Eae24 and Eae26. We tested the parental DA strain and six recombinant congenic strains that include overlapping fragments of this region in MOG-EAE. Eae24 and Eae25 showed significant protection during the acute phase of EAE, whereas Eae25 and Eae26 significantly modified severity but not susceptibility. The smallest congenic fragment, which carries Eae25 alone, influenced both susceptibility and severity, and protected from the chronic phase of disease. These results support the multiple QTLs identified in the AIL. By demonstrating several QTLs comprising immune-related genes, which potentially interact, we provide a significant step toward elucidation of the polygenically regulated pathogenesis of MOG-EAE and possibly multiple sclerosis (MS), and opportunities for comparative genetics and testing in MS case-control cohorts.

Trypanosoma irwini n. sp (Sarcomastigophora: Trypanosomatidae) from the koala ( Phascolarctos cinereus).

The morphology and genetic characterization of a new species of trypanosome infecting koalas (Phascolarctos cinereus) are described. Morphological analysis of bloodstream forms and phylogenetic analysis at the 18S rDNA and gGAPDH loci demonstrated this trypanosome species to be genetically distinct and most similar to Trypanosoma bennetti, an avian trypanosome with a genetic distance of 0.9% at the 18S rDNA and 10.7% at the gGAPDH locus. The trypanosome was detected by 18S rDNA PCR in the blood samples of 26 out of 68 (38.2%) koalas studied. The aetiological role of trypanosomes in koala disease is currently poorly defined, although infection with these parasites has been associated with severe clinical signs in a number of koalas. Based on biological and genetic characterization data, this trypanosome species infecting koalas is proposed to be a new species Trypanosome irwini n. sp.

Increased expansion of the lung stimulates calmodulin 2 expression in fetal sheep.

Obstruction of the fetal trachea causes the lungs to expand with accumulated liquid. Although this is a potent stimulus for lung growth, the mechanisms involved are unknown. Our aim was to identify genes that are differentially expressed as a result of increased fetal lung expansion. Using differential display RT-PCR, we isolated a cDNA fragment partially encoding calmodulin 2 (CALM2) and identified the remainder of the coding region by 5'-rapid amplification of cDNA ends. Differential expression of CALM2 was confirmed by Northern blot analysis; CALM2 mRNA levels were increased to 161 +/- 5% of control at 2 days of increased lung expansion, induced by tracheal obstruction (TO), and had returned to control levels at days 4 and 10. Using in situ hybridization analysis, we found that the proportion of CALM2-labeled cells increased from 10.3 +/- 1.0% to 21.4 +/- 6.8% by 2 days of TO. This increase in CALM2 expression was reflected by a tendency for calmodulin protein levels to increase from 122.7 +/- 17.3 to 156.5 +/- 17.7 at 2 days of TO. Thus increases in fetal lung expansion result in time-dependent changes in CALM2 mRNA levels, which closely parallels the changes in lung DNA synthesis rates. As calmodulin is essential for cell proliferation, increased CALM2 mRNA levels may reflect an important role for calmodulin in expansion-induced fetal lung growth.

Control of food intake in the obese.

Food intake (eating) is a form of behavior that is subject to conscious control. In practice, many obese and weight-gaining individuals claim that their eating is out of (their) control. Mechanistic models describe the interplay of biological and environmental forces that control food intake. However, because human food intake is characterized by individuals intervening to adjust their own patterns of behavior, food intake should reflect interactions among biology, environment, and attempted self-imposed control of behavior. In general, humans display a system of weight regulation that is asymmetrical--a reduction in body weight is strongly defended but weight gain is not. The body seems to tolerate a positive energy balance. There is no mechanism that can detect a positive energy balance per se or that can implement a sufficiently strong correction to behavior to maintain body weight in an environment that promotes consumption. The evolutionary process has favored biological traits associated with preferences for high energy density (sweet and/or fatty) energy-yielding foods. The control of food intake in obese or weight-gaining individuals may display various risk factors that favor an increase in energy. These include the preference for high energy-dense over low energy-dense foods, weak postprandial inhibitory signaling, strong hunger traits associated with low leptin levels after weight loss, and the consumption of fatty foods. In addition, many individuals (up to 47% of some samples) display binge eating patterns, whereas approximately 16% show either night eating or nocturnal eating. Because energy expenditure is only loosely coupled to energy intake, sedentariness does not down-regulate food intake.

Effects of glycosylated recombinant human granulocyte colony-stimulating factor after high-dose cytarabine-based induction chemotherapy for adult acute myeloid leukaemia.

The Australian Leukaemia Study Group (ALSG) investigated whether G-CSF would accelerate haemopoietic recovery after induction treatment for acute myeloid leukaemia (AML) intensified with high-dose cytarabine, and therefore improve response rates and survival. Patients were randomised to receive lenograstim (glycosylated recombinant human G-CSF) 5 microg per kg body weight subcutaneously daily from day 8 after starting chemotherapy, or no cytokine, following chemotherapy with cytarabine 3 g/m2 every 12 h on days 1, 3, 5, and 7, together with idarubicin 9 or 12 mg/m2 on days 1, 2, and 3, plus etoposide 75 mg/m2 on days 1 to 7 inclusive. Patients had untreated AML, and were aged 16 to 60 years. Overall, 54 evaluable patients were randomised to receive lenograstim and 58 to no cytokine. Patients in the lenograstim arm had a significantly shorter duration of neutropenia <0.5 x 10(9)/l compared to patients in the no cytokine arm (median 18 vs 22 days; P = 0.0005), and also shorter duration of total leucopenia <1.0 x 10(9)/l (17 vs 19 days; P = 0.0002), as well as a reduction in duration of treatment with therapeutic intravenous antibiotics (20 vs 24 days; P= 0.015) and a trend to reduced number of days with fever >38.0 degrees C (9 vs 12 days; P = 0.18). There were no differences between the two groups in platelet recovery, red cell or platelet transfusions, or non-haematological toxicities. For patients achieving CR after their first induction course, a reduction in the time to the start of the next course of therapy was observed in the lenograstim arm, from a median of 40.5 days to a median of 36 days (P = 0.082). The overall complete response rates to chemotherapy were similar, 81% in the lenograstim arm vs 75% for the no cytokine arm (P = 0.5), and there was no significant difference in the survival durations. We conclude that the granulopoietic stimulating effect of G-CSF is observed after induction therapy for AML intensified by high-dose cytarabine, resulting in an improvement in a number of clinically important parameters with no major adverse effects.

Self-help countermeasure strategies for populations living within contaminated areas of Belarus, Russia and Ukraine.

Countermeasures have been effectively employed within intensive agricultural systems in areas of the Former Soviet Union (FSU) affected by the Chernobyl accident. However, ingestion doses continue to be elevated in some areas as a result of few foodstuffs which are collected from the wild or produced by the household. Forest fungi and berries, and milk from privately owned cattle are the most notable contributors to 137Cs intakes amongst these foodstuffs. In this paper we consider advice which would help affected populations to both understand the importance of these exposure routes and to reduce their exposure. In addition to the potential radiological benefits, self-help schemes are highly cost-effective and likely to have a positive psychological influence on populations living within contaminated areas of the FSU. Evidence to suggest that the transfer of radiocaesium to cow milk is considerably higher in the FSU than within western Europe and North America is discussed.

Re-expression of pulmonary surfactant proteins following tracheal obstruction in fetal sheep.

Increased fetal lung expansion, induced by tracheal obstruction (TO), is a potent stimulus for fetal lung growth, but rapidly reduces surfactant protein (SP) mRNA levels. Our aim was to determine the time course for the re-expression of the surfactant proteins in fetal lung tissue following the release of a TO and to relate these to the changes in lung liquid volume. Fetal sheep were exposed to either: (1) no treatment (controls); (2) 4 days of TO; (3) 4 days of TO, followed by release of the obstruction for 24 h; (4) 4 days of TO followed by release of the obstruction for 3 days. Four days of TO increased lung liquid volumes from 26.8 +/- 1.9 to 72.0 +/- 5.6 ml kg(-1) and reduced SP-A, SP-B and SP-C mRNA levels to 38.5 +/- 10.7, 56.8 +/- 10.3 and 18.3 +/- 5.3 % of control values, respectively. One day after TO release, lung liquid volumes were reduced to 17.4 +/- 5.3 ml kg(-1) (control 128 days, 31.0 +/- 3.8 ml kg(-1)) and SP-A and SP-B mRNA levels were not different from control levels. In contrast, SP-C mRNA levels only increased to 45.4 +/- 17.3 % of control. Three days after TO release, lung liquid volumes increased to 48.0 +/- 8.5 ml kg(-1) and SP-A and SP-B mRNA levels were reduced to 48.8 +/- 10.2 % and 71.5 +/- 19.8 % of control, respectively; SP-C mRNA levels remained at 35.3 +/- 12.3 % of control. Following the release of a TO, SP-A, SP-B and SP-C mRNA levels were closely and inversely related to the volume of lung liquid. Based on these relationships, the lung liquid volumes that equate to 100 % expression were considerably less than control lung volumes (< 10 vs. 30-40 ml kg(-1)) in fetuses of this age. Thus, the changes in fetal lung SP-A, SP-B and SP-C mRNA levels following the release of a TO are variable, differ between the proteins and are closely related to the changes in lung liquid volumes. We conclude that the re-expression of surfactant proteins following TO is variable and that the change in lung liquid volume is potentially a good indicator for surfactant protein re-expression. Experimental Physiology (2001) 86.1, 55-63.