Habitat segregation and cryptic adaptation of species of Periophthalmus (Gobioidei: Gobiidae).

A study was conducted on the habitat distribution of four sympatric species of Periophthalmus (the silver-lined mudskipper Periophthalmus argentilineatus, the slender mudskipper Periophthalmus gracilis, the kalolo mudskipper Periophthalmus kalolo and the Malacca mudskipper Periophthalmus malaccensis) from northern Sulawesi. Molecular phylogenetic reconstructions based on one mtDNA marker (16S) were used to validate the morphological taxa, identifying five molecular clades. Periophthalmus argentilineatus includes two molecular species, which are named Periophthalmus argentilineatus clades F and K. Multivariate direct gradient analysis show that these species form three distinct ecological guilds, with the two molecular species occurring in different guilds. Periophthalmus clade F is ecologically eurytypic; Periophthalmus clade K and P. kalolo are prevalent in ecosystems isolated by strong oceanic currents and at shorter distances from the sea; P. gracilis plus P. malaccensis are prevalent in ecosystems connected by shallow coastal waters, in vegetated habitats at larger distances from the sea. This indicates for the first time that mudskipper species exhibit a range of adaptations to semiterrestrialism not only within genera, but even within morphospecies, delineating a much more complex adaptive scenario than previously assumed.

Phylogeography and demographic history of two widespread Indo-Pacific mudskippers (Gobiidae: Periophthalmus).

This study provides a first description of the phylogeographic patterns and evolutionary history of two species of the mudskipper genus Periophthalmus. These amphibious gobies are distributed throughout the whole Indo-Pacific region and Atlantic coast of Africa, in peritidal habitats of soft-bottom coastal ecosystems. Three sequence datasets of two widely distributed species, Periophthalmus argentilineatus and P. kalolo, were obtained by amplifying and sequencing two mtDNA markers (D-loop and 16S rDNA) and the nDNA rag1 region. The three datasets were then used to perform phylogeographic, demographic and population genetic analyses. Our results indicate that tectonic events and past climatic oscillations strongly contributed to shape present genetic differentiation, phylogeographic and demographic patterns. We found support for the monophyly of P. kalolo, and only shallow genetic differentiation between East-African and Indo-Malayan populations of this species. However, our collections of the morphospecies P. argentilineatus include three molecularly distinct lineages, one of them more closely related to P. kalolo. The presence of Miocenic timings for the most recent common ancestors of some of these morphologically similar clades, suggests the presence of strong stabilising selection in mudskippers' habitats. At population level, demographic analyses and palaeoecological records of mangrove ecosystems suggest that Pleistocene bottlenecks and expansion plus secondary contact events of the studied species were associated with recurrent sea transgressions during interglacials, and sea regressions or stable regimes during glacials, respectively.

Differentiation and adaptive radiation of amphibious gobies (Gobiidae: Oxudercinae) in semi-terrestrial habitats.

During several surveys made in the region of the lower Fly River and delta, Papua New Guinea, nine species of oxudercine gobies (Gobiidae: Oxudercinae) were recorded: Boleophthalmus caeruleomaculatus, Oxuderces wirzi, Periophthalmodon freycineti, Periophthalmus darwini, Periophthalmus novaeguineaensis, Periophthalmus takita, Periophthalmus weberi, Scartelaos histophorus and Zappa confluentus. An exploratory multivariate analysis of their habitat conditions discriminated five guilds, differentially distributed in habitats with different quantities of environmental water and three guilds corresponding to different levels of salinity. A partial correspondence between phylogenetic and ecological categories suggested the presence of parallel adaptive radiations within different genera. In particular, the species found in the most terrestrial habitats (P. weberi) was also found in the widest range of conditions, suggesting that colonization of extreme semi-terrestrial and freshwater habitats by this species was facilitated by eurytypy. It is proposed that these findings provide insight into convergent adaptations for the vertebrate eco-evolutionary transition from sea to land.

Leeches on mudskippers: host-parasite interaction at the water's edge.

A host-parasite relationship was observed, for the first time, between a piscicolid leech and a species of amphibious goby (Scartelaos tenuis) from an intertidal mud flat in southern Iran. Morphological and molecular investigations assign the leech to Zeylanicobdella arugamensis. Of the 3 endemic and sympatric mudskipper species living in the Persian Gulf (S. tenuis, Boleophthalmus dussumieri, and Periophthalmus waltoni), leeches were only found on S. tenuis (prevalence and mean intensity = 71.4% and 2.3 +/- 2.5, respectively), which is also the most-aquatic mudskipper species. Scartelaos tenuis is not the largest species, but more leeches (> or =4 leeches/host) were found on larger specimens (>12 cm standard length [SL]). Nonetheless, in aquaria, leeches also attached on P. waltoni. This suggests either an ecological partitioning of host-parasite complexes, determined by host habitat selection, or leech limited-resistance to air exposure, or both.

Cold air challenge of airway hyperreactivity in children: dose-response interrelation with a reaction plateau.

A previous study of cold air challenge (CACh) in children with asthma produced indirect evidence for the existence of a reaction plateau. To examine directly this phenomenon, 17 children, mean age 13 1/2 years, were challenged by isocapnic hyperventilation with -10 degrees C air at 75% of maximal voluntary ventilation for 10 minutes (extended CACh [ECACh]). Each minute FEV1 and maximum expiratory flow at 25% remaining vital capacity (V25) were measured. During "recovery" these measurements were repeated every minute for 10 minutes. Analysis of the cumulative dose-response curves constructed from the measurements revealed that a reaction plateau was reached in the last minutes of the challenge by both functions in each child. Induced changes in absolute terms were similar for both functions (FEV1: -28 +/- 12% predicted; V25: -29 +/- 17% predicted), but V25 started at a lower baseline (FEV1: 81 +/- 15% predicted; V25: 48 +/- 27% predicted) and thus arrived at a higher degree of obstruction (FEV1: 53 +/- 19% predicted; V25: 19 +/- 13% predicted). Together with the reaction plateau developing faster for V25, this indicated a dose-response influenced by baseline small airway obstruction. Although the size of the reaction differed from one child to the other (FEV1: -5% to -50% predicted; V25: -4% to -77% predicted), interindividual variability in the development of the reaction decreased toward the end of the challenge and was minimal at the plateau and in the early minutes of "recovery."(ABSTRACT TRUNCATED AT 250 WORDS)

Cold air provocation of airway hyperreactivity in patients with cystic fibrosis.

Thirty-four patients with cystic fibrosis (CF) were assessed for baseline pulmonary functions before, and 5 and 15 minutes after cold air challenge (CACh). Most of the patients had no change in forced expiratory volume in 1 second (FEV1) and maximum expiratory flow at 25% vital capacity (Vmax25%VC) post-CACh. Five patients responded with reduced FEV1 and 13 with reduced Vmax25%VC. However, paradoxical increases were noted in 10 patients for FEV1 and in 5 for Vmax25%VC. Paradoxical responses were most frequent in patients with severe lung disease. The explanation for this variability may lie in the varying degrees of airway instability and volume of airway contribution (VAC) to early flows, resulting from the damage caused by chronic infection. Conventional challenges may be useless in determining the true incidence of bronchial hyperreactivity in patients with CF.

Bronchodilators increase airway instability in cystic fibrosis.

Supramaximal flow transients of partial expiratory flow-volume curves are caused by a rapidly emptying compartment. By superimposing a maximal and a series of partial expiratory flow-volume curves, the volume of the flow transient equivalent for the maximal curve was estimated (volume of airway contribution = VACMEFV). This flow transient equivalent is caused by an extra dead space, created in the large airways by a full inspiration. In 18 children with cystic fibrosis (CF), routine pulmonary functions and VACMEFV were measured before and after bronchodilator medication. Baseline VACMEFV correlated directly with the curvilinearity of the flow-volume curve and inversely with the clinical and radiologic score. Significantly, bronchodilator medication improved FVC, FEV1, FEF25-75, VC, PEF, Raw, and also VACMEFV. In 6 children, VEmax25 increased as a result of apparent peripheral bronchodilation. In 3 others, end-expiratory flow increased slightly but the expanded VACMEFV included the measuring point invalidating the measurement. In the remaining 9 patients, VEmax25 decreased after bronchodilator. As an apparent discrepancy, FEV1, FVC, PEF, VC, FEF25-75 increased, and Raw decreased in 4 to 9 patients. The volumes and flow rates measured early in forced expiration and the end-expiratory flow behaved differently because VACMEFV expanded beyond the measuring points of early expiratory and mid-expiratory flow rates. As the bronchodilator rendered the compliant large airways still more distensible, the amount of air emptied from the dead space in early forced expiration increased. Simultaneously, end-expiratory flow decreased because of enhanced airway compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Individualization of tobramycin dosage in patients with cystic fibrosis.

Tobramycin was administered to 52 patients, ages 2 months to 27 years, with cystic fibrosis during acute exacerbation of Pseudomonas-related pulmonary infection. Elimination pharmacokinetics of tobramycin was characterized for each patient after intravenous administration using a standardized infusion technique. The minimal inhibitory concentration was determined for Pseudomonas strains isolated from 26 of the 52 patients. The pharmacokinetic parameters of individual patient were used to adjust the dose and dosing interval to maintain the serum concentration of tobramycin above the minimal inhibitory concentration for the infecting organism for at least 75% of the dosing interval without exceeding the maximum concentration of 12 micrograms/ml or a minimum concentration of 2.0 micrograms/ml. This resulted in an increase of the mean daily dose of tobramycin to 12 mg/kg from an initial mean dose of 5.5 mg/kg and a reduction of the dosing interval from 8 hours to 4 or 6 hours for patients greater than 1 year of age. Significant differences between the pharmacokinetic profiles of the infants and older patients were observed.

Cold air challenge of airway hyperreactivity in children: practical application and theoretical aspects.

In 23 children with asthma and 18 healthy controls, cold air challenge ( CACh ) was done twice during the same half day, and in the asthmatics a third time together with a histamine challenge (HCh) 2 wk later. Pulmonary functions were tested before and after each challenge. No overlapping of individual responses to CACh in seven forced expiratory flow tests proved the power of discrimination of this technique in children. The limits of "normal" reactions ranged from minus 9% for larger airway-related to 26% for smaller airway-related flows. Short-term reproducibility of induced changes, in percentage of baseline, was excellent (r = 0.815-0.954); in percentage of predicted postchallenge abnormality it was even better (r = 0.926-0.975). The response in small airway-related flow rates (-43.1 +/- 12.8 to -51.9 +/- 16.8% of baseline) was much larger than in others (-27.6 +/- 14.6 to -32.1 +/- 17.3% of baseline). This, the different baseline-to-response correlations in various measurements, and the divergent dose response to colder versus less cold air in large (60.7 +/- 21.9 versus 65.4 +/- 21.5% predicted, postchallenge values) and small airway-related tests (28.9 +/- 18.7 versus 29.5 +/- 15.1% predicted, postchallenge values) in asthmatic children suggest a predetermined, small airway-related limitation of individual reactivity, which is independent of the baseline situation. All asthmatics responded positively to HCh but quantitative results of the two methods did not correlate. Responses to CACh also better characterized the clinical severity of asthma than those of HCh.(ABSTRACT TRUNCATED AT 250 WORDS)

Testing the mutagenicity of malondialdehyde and formaldehyde by the Drosophila mosaic and the sex-linked recessive lethal tests.

The mutagenicities of malondialdehyde and formaldehyde were tested by screening each for genetic mosaics of Drosophila melanogaster and by the Muller-5 test for sex-linked recessive lethal mutations. For comparison, the effects of X-rays were also assayed by the above technique. Malondialdehyde, a degradation product of polyunsaturated fatty acids, was found to be a weak mutagen by the above criteria; it induced point mutations and chromosome exchanges at low frequency, as proved by the mosaic test, but failed to induce detectable sex-linked lethality. Formaldehyde was more mutagenic than malondialdehyde; beside induction of mosaic spots it induced sex-linked recessive lethal mutations, but only in the larval testes of Drosophila. Formaldehyde also induced disintegration of the clones. Formaldehyde treatment (feeding larvae with formaldehyde-containing food for about 4 days) was 5 times more mutagenic than malondialdehyde treatment and 5 times less effective than irradiation by 1000 R of X-rays. Wing mosaicism offers a more sensitive way to detect mutagenesis as compared with eye mosaicism. It is suggested that aldehyde-induced mosaic spots derive from mitotic recombination and point mutations.

Current concepts of respiratory diseases in childhood: the significance of physiological development.

Recent advances in pulmonary physiology have led to new concepts in the understanding of childhood respiratory disorders. The functional development of the respiratory system appears responsible for most of the age-related attributes of pediatric lung diseases. Increased understanding of the altered physiology of these disorders creates a new and improved basis for supportive care and therapy. The recognition of long lasting functional disturbances caused by some seemingly trivial childhood respiratory disorders suggests a close relationship to chronic obstructive pulmonary disease in adulthood. Relevant developmental risk factors are defined; their influence on the manifestation of common pediatric respiratory disorders is discussed.

Cystic fibrosis diagnosed in a black adolescent with long-standing, unstable diabetes mellitus.

A case is reported of a black youth whose marked diabetic lability was stabilized subsequent to establishing the diagnosis of cystic fibrosis and treatment of the pancreatic exocrine deficiency. The patient had no evidence of pulmonary involvement secondary to cystic fibrosis, but had a partial immunoglobulin A deficiency. A possible common etiology for diabetes mellitus and cystic fibrosis is discussed.

Measurement of regional lung function by tetrapolar electrical impedance plethysmography.

This study demonstrates the clinical feasibility of atraumatically measuring dynamic regional lung function with tetrapolar electrical impedance plethysmography (EIP) in the pediatric age group. A tetrapolar electrode system was used because of its ability to detect local baseline and pulsatile impedance changes, minimal electrode-tissue impedance interference, and uniform current distribution. Studies performed on 4 children 4 to 15 years old with various pulmonary diseases are presented. The information obtained on their regional ventilation and pulsatile perfusion by EIP was found to agree closely with pulmonary ventilation and perfusion scans. In one case, EIP detected pulsatile perfusion abnormalities which were not apparent in the non-pulsatile perfusion scan but were demonstrated by cineangiography. It is concluded that tetrapolar EIP can provide safe, reliable regional information about ventilation and perfusion in diseased lungs, and because of its atraumatic approach, is technically most suitable for use in children.

Pulmonary function in survivors of Wilm's tumor. Patterns of impairment.

Whole-lung irradiation in Wilms' Tumor patients has been given prophylactically and for treatment of metastasis. Thirty-three children with Wilm's tumor who have survived for 4 to 20 years from the time of diagnosis were avaiable for study. Whole-lung irradiation was given in doses from 1163 to 1370 rads (orthovoltage). Eighteen patients (Group N) received no irradiation to the lungs. The remaining 15 patients were divided according to whether pulmonary irradiation was given for metastatic disease (Group M--10 patients) or for prophylactic treatment (Group P--five patients). All but five patients in Group N received at least one course of actinomycin D. A routine set of pulmonary function tests was done to assess possible abnormalities of lung volume and the mechanics of breathing. Group N was normal. The findings in Group M suggested moderately reduced lung volumes and may have also reflected obstruction of the large airways and/or a limited expiratory effort. Group P had essentially normal lung volumes but also appeared to have obstruction of the larger airways. Abnormalities were generally not severe; only two patients, in Group M, were symptomatic. Excess irradiation, presence of metastatsis, additional lung irradiation, and pneumonitis may have contributed to morbidity.