Progressive changes in cortical state before and after spontaneous arousals from sleep in elderly and middle-aged women

Arousals are often considered to be events which have an abrupt onset and offset, indicating abrupt changes in the state of the cortex. We hypothesized that cortical state, as reflected in electroencephalograph (EEG) signals, exhibits progressive systematic changes before and after a spontaneous, isolated arousal and that the time courses of the spectral components of the EEG before and after an arousal would differ between healthy middle-aged and elderly subjects. We analyzed the power spectrum and Sample Entropy of the C3A2 EEG before and after isolated arousals from 20 middle-aged (47.2±2.0 years) and 20 elderly (78.4±3.8 years) women using polysomnograms from the Sleep Heart Health Study database. In middle-aged women, all EEG spectral band powers <16 Hz exhibited a significant increase relative to baseline at some time in the 21 s before an arousal, but only low- (0.2-2.0 Hz) and high-frequency (2.0-4.0 Hz) delta increased in elderly and only during the last 7 s pre-arousal. Post-arousal, all frequency bands below 12 Hz transiently fell below pre-arousal baseline in both age groups. Consistent with these findings, Sample Entropy decreased steadily before an arousal, increased markedly during the arousal, and remained above pre-arousal baseline levels for ∼30 s after the arousal. In middle-aged, but not in elderly, women the presence of early pre-arousal low delta power was associated with shorter arousals. We propose that this attenuation of the effect of the arousing stimulus may be related to the slow (<1 Hz) cortical state oscillation, and that prolonged alterations of cortical state due to arousals may contribute to the poor correlation between indices of arousals and indices of sleepiness or impaired cognitive function.

Characterization and application of multiple genetic markers for Plasmodium malariae

Plasmodium malariae, a protozoan parasite that causes malaria in humans, has a global distribution in tropical and subtropical regions and is commonly found in sympatry with other Plasmodium species of humans. Little is known about the genetics or population structure of P. malariae. In the present study, we describe polymorphic genetic markers for P. malariae and present the first molecular epidemiological data for this parasite. Six microsatellite or minisatellite markers were validated using 76 P. malariae samples from a diverse geographical range. The repeat unit length varied from 2 to 17 bp, and up to 10 different alleles per locus were detected. Multiple genotypes of P. malariae were detected in 33 of 70 samples from humans with naturally acquired infection. Heterozygosity was calculated to be between 0.236 and 0.811. Allelic diversity was reduced for samples from South America and, at some loci, in samples from Thailand compared with those from Malawi. The number of unique multilocus genotypes defined using the 6 markers was significantly greater in Malawi than in Thailand, even when data from single genotype infections were used. There was a significant reduction in the multiplicity of infection in symptomatic infections compared with asymptomatic ones, suggesting that clinical episodes are usually caused by the expansion of a single genotype.

Genotyping of Plasmodium falciparum infections by PCR: a comparative multicentre study

Genetic diversity of malaria parasites represents a major issue in understanding several aspects of malaria infection and disease. Genotyping of Plasmodium falciparum infections with polymerase chain reaction (PCR)-based methods has therefore been introduced in epidemiological studies. Polymorphic regions of the msp1, msp2 and glurp genes are the most frequently used markers for genotyping, but methods may differ. A multicentre study was therefore conducted to evaluate the comparability of results from different laboratories when the same samples were analysed. Analyses of laboratory-cloned lines revealed high specificity but varying sensitivity. Detection of low-density clones was hampered in multiclonal infections. Analyses of isolates from Tanzania and Papua New Guinea revealed similar positivity rates with the same allelic types identified. The number of alleles detected per isolate, however, varied systematically between the laboratories especially at high parasite densities. When the analyses were repeated within the laboratories, high agreement was found in getting positive or negative results but with a random variation in the number of alleles detected. The msp2 locus appeared to be the most informative single marker for analyses of multiplicity of infection. Genotyping by PCR is a powerful tool for studies on genetic diversity of P. falciparum but this study has revealed limitations in comparing results on multiplicity of infection derived from different laboratories and emphasizes the need for highly standardized laboratory protocols.

Tuberculosis control and molecular epidemiology in a South African gold-mining community

BACKGROUND

Gold miners have very high rates of tuberculosis. The contribution of infections imported into mining communities versus transmission within them is not known and has implications for control strategies.

METHODS

We did a prospective, population-based molecular and conventional epidemiological study of pulmonary tuberculosis in a group of goldminers. Clusters were defined as groups of patients with Mycobacterium tuberculosis isolates with identical IS6110 DNA fingerprints. We compared the frequency of possible risk factors in the clustered and non-clustered patients whose isolates had fingerprints with more than four bands, and re-interviewed members of 45 clusters.

FINDINGS

Of 448 patients, ten were excluded because they had false-positive cultures. Fingerprints were made in 419 of 438, of which 371 had more than four bands. 248 of 371 were categorised into 62 clusters. At least 50% of tuberculosis cases were due to transmission within the community. Patients who had failed treatment at entry to the study were more likely to be in clusters (adjusted odds ratio 3.41 [95% CI 1.25-9.27]). Patients with multidrug-resistant isolates were more likely to have failed treatment but were less likely to be clustered than those with a sensitive strain (0.27 [0.09-0.83]). HIV infection was common (177 of 370 tested) but not associated with clustering.

INTERPRETATION

Despite a control programme that cures 86% of new cases, most tuberculosis in this mining community is due to ongoing transmission. Persistently infectious individuals who have previously failed treatment may be responsible for one third of tuberculosis cases. WHO targets for cure rates are not sufficient to interrupt transmission of tuberculosis in this setting. Indicators that are more closely linked to the rate of ongoing transmission are needed.

Genetic diversity and dynamics of plasmodium falciparum and P. vivax populations in multiply infected children with asymptomatic malaria infections in Papua New Guinea

We describe the dynamics of co-infections of Plasmodium falciparum and P. vivax in 28 asymptomatic children by genotyping these species using the polymorphic loci Msp2 and Msp3alpha, respectively. The total number of Plasmodium spp. infections detected using 3 day sampling over 61 days varied between 1 and 14 (mean 6.6). The dynamics of P. falciparum and P. vivax genotypes varied greatly both within and amongst children. Periodicity in the detection of P. falciparum infections is consistent with the synchronous replication of individual genotypes. Replication synchrony of multiple co-infecting genotypes was not detected. In 4-year-old children P. falciparum genotype complexity was reduced and episodes lasted significantly longer (median duration > 60 days) when compared to children aged 5-14 years (median duration 9 days). P. vivax genotype complexity was not correlated with age but the episode duration was also longer for this species in 4-year-olds than in older children but was not as long as P. falciparum episodes. Recurrence of P. falciparum and P. vivax genotypes over weeks was observed. We interpret these major fluctuations in the density of genotypes over time as the result of the mechanism of antigenic variation thought to be present in these Plasmodium species.

Age- and species-specific duration of infection in asymptomatic malaria infections in Papua New Guinea

The burden and duration of asymptomatic malaria infections were measured in residents of the malaria endemic village of Gonoa, Madang Province, Papua New Guinea. Plasmodium falciparum, P. vivax and P. malariae infections in people aged 4 years to adulthood were compared. Frequent sampling at 3-day intervals for up to 61 days allowed assessment of individual episodes of infection. Statistical assessment of P. falciparum detection revealed a periodicity consistent with synchronous replication of this species over periods up to 27 days. The duration of P. falciparum episodes was longer across all age groups than that of P. vivax and P. malariae. A trend for decreasing duration with age was also noted in data from each species. This was most prominent in P. falciparum infections: median duration in 4-year-olds was > 48 days compared with a median between 9 and 15 days in older children and adults. The results are consistent with the slow acquisition of immunity to antigenically diverse Plasmodium populations and suggest a faster rate of acquisition to P. vivax and P. malariae than to P. falciparum.

Cross-species interactions between malaria parasites in humans

The dynamics of multiple Plasmodium infections in asymptomatic children living under intense malaria transmission pressure provide evidence for a density-dependent regulation that transcends species as well as genotype. This regulation, in combination with species- and genotype-specific immune responses, results in nonindependent, sequential episodes of infection with each species.

Polymorphism at the merozoite surface protein-3alpha locus of Plasmodium vivax: global and local diversity

Allelic diversity at the Plasmodium vivax merozoite surface protein-3alpha (PvMsp-3alpha) locus was investigated using a combined polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) protocol. Symptomatic patient isolates from global geographic origins showed a high level of polymorphism at the nucleotide level. These samples were used to validate the sensitivity, specificity, and reproducibility of the PCR/RFLP method. It was then used to investigate PvMsp3alpha diversity in field samples from children living in a single village in a malaria-endemic region of Papua New Guinea, with the aim of assessing the usefulness of this locus as an epidemiologic marker of P. vivax infections. Eleven PvMsp-3alpha alleles were distinguishable in 16 samples with single infections, revealing extensive parasite polymorphism within this restricted area. Multiple infections were easily detected and accounted for 5 (23%) of 22 positive samples. Pairs of samples from individual children provided preliminary evidence for high turnover of P. vivax populations.

Developmental shift in the relative percentages of lung fibroblast subsets: role of apoptosis postseptation

We have used the lipophilic, fluorescent dye Nile red and flow cytometry to identify and isolate two rat lung fibroblast subsets, lipid-containing interstitial cells (LICs) and non-LICs (NLICs) and to quantitate developmental changes in the relative percentages of these subsets. A significant decrease was observed in the percentage of LICs (from 79.0 +/- 3.8% on postnatal day 4 to 28.6 +/- 4.2% on day 30; P < 0.0001). To determine whether one or both subsets undergo apoptosis postseptation, fibroblasts from 16- to 18-day rats were treated with BODIPY-conjugated dUTP to label DNA strand breaks, which were then quantitated by flow cytometry. Apoptotic cells were judged to be predominantly LICs based on flow cytometric estimates of cell size and granularity and on light-microscopic colocalization of intracellular lipid and Hoechst-positive apoptotic bodies. Cell proliferation was compared in LICs and NLICs with both an in vitro [(3)H]thymidine incorporation assay and cell cycle analysis of propidium iodide-stained cells. Results of both assays indicated that on days 4-5, LICs proliferated more rapidly than NLICs. Tropoelastin and fibronectin mRNA expression, evaluated by RT-PCR, indicated that although tropoelastin mRNA levels did not differ, fibronectin mRNA levels were approximately ninefold greater in LICs. These results demonstrate the feasibility of a flow cytometric assay for the analysis of size, granularity, and intracellular lipid content of neonatal rat lung fibroblast subsets. Subsets differed substantially with respect to proliferative capacity, fibronectin mRNA expression, and incidence of apoptosis postseptation. Together with the observed changes in relative percentages of fibroblast subsets with age, these data suggest that the ratio of LICs to NLICs could be a critical determinant of fibroblast function during lung development.

The postnatal age of rat lung fibroblasts influences G1/S phase transition in vitro

In the neonatal rat lung, alveolar development occurs from postnatal Days 4-13, during which time there is a fourfold increase in interstitial fibroblasts. Factors influencing emergence of new septa and cell proliferation associated with septal elongation have yet to be identified, in part because of difficulties inherent in studying this process in vivo. Using flow cytometric analysis of the DNA content of freshly isolated lung fibroblasts, we found that proliferation, as indicated by the percentage of cells in S plus G2/M phases, peaked on postnatal Day 4 (P < 0.04). By Days 9-10 the proliferation rate was lower than on Days 3, 4, 5, or 6 (P < 0.005). We then evaluated rates of in vitro proliferation as a function of postnatal age in first passage fibroblasts and found that the proliferative phenotype expressed in vivo persists in vitro. Fibroblasts from 4-5-d-old pups increased in number and incorporated 3H-thymidine at a faster rate than did fibroblasts obtained from pups at other postnatal ages (P < 0.0001). Age-dependent differences in cell cycle transit time were compared in fibroblasts synchronized by serum starvation and analyzed by flow cytometry at 2-h intervals from 13-21 h after release from serum starvation. A greater percentage of cells from 5-d-old pups entered S phase during this period than was seen for cells obtained from 2-, 9-, 13-, or 23-d-old rat pups (P = 0.0001). Cells from 5-, 9-, and 13-d-old pups reentered G0/G1 by 21 h after release from serum starvation, in contrast to fibroblasts from 2- and 23-d-old rats which did not. Throughout the 15-h period after release from serum starvation, levels of cyclin E, which peaks at the G1/S border, were highest in the 5-d-old cells (P < 0.025). Synchronization with 2.5 mM hydroxyurea which inhibits DNA synthesis completely abolished age-related differences in cell cycle transit time, implying that age-dependent differences in lung fibroblast proliferation rates are the result of events occurring before S-phase entry.

Lung fibroblasts undergo apoptosis following alveolarization

In the rat lung, primary saccules are transformed into alveoli from postnatal Days 4 to 13, after which time there is a 20% reduction in the number of lung fibroblasts as the interstitial volume of the alveolar walls decreases. Our objective was to determine whether apoptosis is a factor in the observed decrease in the number of interstitial lung fibroblasts beyond Day 13. We used both histologic and flow cytometric assays to detect in lung fibroblasts the DNA fragmentation and condensation that are characteristic of apoptosis. In addition, we evaluated levels of bcl-2 and BAX messenger RNAs (mRNAs) using a reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Apoptotic cells were quantitated in glycol methacrylate-embedded sections of neonatal rat lungs using the terminal transferase dUTP-digoxygenin nick end-labeling (TUNEL) method. Although TUNEL-positive interstitial cells were observed in the lungs of rats ranging in age from 10 to 16 d, a dramatic increase in apoptotic cells was seen on Day 17. Although diminished in number, TUNEL-positive cells were still present on Day 28. Hoechst-stained apoptotic bodies were observed in isolated lung cells that were vimentin-positive and factor VIII-negative, which identified the apoptotic cells as fibroblasts as opposed to endothelial cells. Flow cytometric analysis of freshly isolated lung fibroblasts stained with Hoechst 33342 indicated a 24% increase in chromatin condensation in cells from 17-d versus 16-d rats. DNA fragmentation was also quantitated by flow cytometry in freshly isolated fibroblasts labeled with BODIPY-conjugated dUTP in the presence of terminal deoxynucleotidyl transferase. The percentage of lung fibroblasts containing fragmented DNA was 51.4 +/- 13.4 in 17-d, 36.9 +/- 8.6 in 18-d, and 13.8 +/- 5.4 in 19-d rat pups. Finally, evaluation by RT-PCR indicated that on postnatal Day 17, mRNA for bcl-2, which inhibits apoptosis, was decreased to 73.5 +/- 11.4% (P < 0.001) of Day 5 controls; whereas mRNA for BAX, which enhances apoptosis, was increased to 243.0 +/- 102.0% (P < 0.001) of Day 5 values. These results demonstrate that rat lung fibroblasts undergo apoptosis after the completion of alveolarization, and suggest that this decrease in fibroblast number plays an important role in the thinning and remodeling of the alveolar walls of the lung.

Transcriptional regulation of tropoelastin expression in rat lung fibroblasts: changes with age and hyperoxia

Elastic fibers are thought to provide structural support for secondary septa as the lung undergoes the transition from the saccular to the alveolar stage. The synthesis of the soluble precursor of elastin, tropoelastin, occurs during a finite developmental period. We have investigated the developmental regulation of tropoelastin gene transcription and mRNA expression in fetal and postnatal rat lung fibroblasts and have assessed the changes in tropoelastin gene expression caused by hyperoxic exposure during secondary septal development. With the use of an RT-PCR assay and intron-specific primers to detect heterogeneous nuclear RNA (hnRNA) and intron-spanning primers to detect mRNA in freshly isolated rat lung fibroblasts, tropoelastin gene expression was found to be upregulated late in gestation. From days 18 to 21 of gestation, there was a 4.5-fold increase in tropoelastin hnRNA (P < 0.0001) and a 6-fold increase in mRNA (P = 0.002). After birth, tropoelastin expression was downregulated. Signals decreased from fetal day 21 to postnatal day 2 for both tropoelastin hnRNA (P = 0. 021) and mRNA (P = 0.043). Tropoelastin hnRNA decreased further from days 2 to 6 (P = 0.04). Both tropoelastin hnRNA and mRNA were again upregulated during alveolarization from days 9 to 11, indicating that, once upregulated, transcription of the tropoelastin gene is not constant but varies with fetal and postnatal age. Exposure to >95% oxygen, when initiated on postnatal day 2 or 3 and continued until day 11, significantly diminished the developmental increase in tropoelastin hnRNA (P < 0.005) and mRNA (P < 0.05) normally seen on days 9-11, indicating that the postnatal upregulation of tropoelastin gene expression is inhibited by hyperoxic exposure in the early postnatal period.

Elevated laminin concentrations in lung secretions of preterm infants supported by mechanical ventilation are correlated with radiographic abnormalities

OBJECTIVE

The objective of this study was to test the hypothesis that the presence of laminin in neonatal tracheal aspirates would be indicative of damage to the structural integrity of the basal laminae of the lung caused by barotrauma and hyperoxia. We predicted that disruption of the basal laminae would be a critical determinant of lung injury and fibrotic repair in the preterm infant whose lungs were ventilated with supplemental oxygen.

STUDY DESIGN

The study group consisted of 23 premature infants in the neonatal intensive care unit whose lungs were ventilated by supplemental oxygen. We quantitated concentrations of laminin and fibronectin from sequential tracheal aspirates by enzyme-linked immunosorbent assays. A two-way analysis of variance was used to compare laminin and fibronectin concentrations in infants with and without radiographic evidence of coarse pulmonary markings indicative of fibrotic repair of lung injury.

RESULTS

The concentrations of laminin, but not fibronectin, were significantly higher throughout the first 5 weeks of life in infants with abnormal chest radiographs at 36 weeks after conception. The concentrations of laminin in infant serum were approximately 1/30 that of tracheal aspirate laminin concentrations, suggesting that little if any of the laminin detected in the tracheal aspirates was derived from the serum.

CONCLUSIONS

Increased concentrations of laminin in tracheal aspirates may be an indication of lung injury and fibrotic repair in the preterm infant.

Recent transmission of tuberculosis in a cohort of HIV-1-infected female sex workers in Nairobi, Kenya

OBJECTIVES

To describe the epidemiological and clinical characteristics of HIV-related tuberculosis in a female cohort, and to investigate the relative importance of recently transmitted infection and reactivation in the pathogenesis of adult HIV-related tuberculosis.

DESIGN

Members of an established cohort of female sex workers in Nairobi were enrolled in a prospective study. Women were followed up regularly and seen on demand when sick.

METHODS

Between October 1989 and September 1992 we followed 587 HIV-infected and 132 HIV-seronegative women. Standard protocols were used to investigate common presentations. Cases of tuberculosis were identified clinically or by culture. All available Mycobacterium tuberculosis strains underwent DNA fingerprint analysis.

RESULTS

Forty-nine incident and four recurrent episodes of tuberculosis were seen in HIV-infected women; no disease was seen in seronegative sex workers (P = 0.0003). The overall incidence rate of tuberculosis was 34.5 per 1000 person-years amongst HIV-infected participants. In purified protein derivative (PPD) skin test-positive women the rate was 66.7 per 1000 person-years versus 18.1 per 1000 person-years in PPD-negative women. Twenty incident cases (41%) were clinically compatible with primary disease. DNA fingerprint analysis of strains from 32 incident cases identified two clusters comprising two and nine patients; allowing for index cases, 10 patients (28%) may have had recently transmitted disease. Three out of 10 (30%) patients who were initially PPD skin test-negative became PPD-positive. Taken together, 26 incident cases (53%) may have been recently infected. DNA fingerprint analysis also identified two (50%) of the four recurrent tuberculosis episodes as reinfection.

CONCLUSIONS

Substantial recent transmission of tuberculosis appears to be occurring in Nairobi amongst HIV-infected sex workers. It may be incorrect to assume in other regions of high tuberculosis transmission that active HIV-related tuberculosis usually represents reactivation of latent infection.

Postnatal age at onset of hyperoxic exposure influences developmentally regulated tropoelastin gene expression in the neonatal rat lung

Upregulation of tropoelastin (TE) gene expression in rat lung interstitial fibroblasts normally occurs during alveolar septation. TE message increases at the end of the first week of life, peaks on days 9-11, and returns to barely detectable levels over the next 7-10 days. Our previous in situ hybridization studies indicated that exposure of pups to > 95% oxygen from 3 to 13 days of age interfered with the increased in TE gene expression in interstitial fibroblasts normally seen during septation. However, when the pups were returned to room air, lung fibroblast TE message levels increased, exceeding levels seen in control lungs during the exposure. In addition, TE message levels remained elevated for a week after levels in control lungs had returned to background. A possible interpretation of these results was that the developmentally regulated increase in TE messenger RNA (mRNA) was downregulated by the hyperoxic exposure but resumed when the pups were returned to a normoxic environment. We report herein the results of a subsequent study conducted to determine whether continued hyperoxic exposure beyond day 13 would further delay the peak in TE mRNA. Rat pups were exposed to 95% O2 from 5 to 17 days of age. TE and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) message levels in lung interstitial fibroblasts were assessed by in situ hybridization. As observed in pups exposed from 3 to 13 days, hyperoxic exposure from days 5 to 17 also extended the period during which TE mRNA levels were elevated. After exposure, TE message levels were 99%, 262%, and 223% of controls on days 19, 21, and 23 respectively. In addition, delaying the exposure 2 days until the pups were 5 days old resulted in an upregulation of TE message, relative to control values, during the hyperoxic exposure. In hyperoxic pups, values for TE message expression were 105%, 152%, 168%, and 144% of control pups on days 9, 11, 13, and 16 respectively. The influence on peak TE message expression of postnatal age at the time of exposure was further explored to verify the results of the 3-13 and 5-17 day exposures. When pups were exposed continuously from 2, 3, 4, 5, or 6 days until 11 days of age, the results of both in situ hybridization and Northern blot analysis confirmed our previous observations, demonstrating that the postnatal age at which hyperoxic exposure is initiated influences TE message expression in the developing lung.

Comparison of secretory component for immunoglobulin A with albumin as reference proteins in tracheal aspirate from preterm infants

OBJECTIVES

To determine whether the concentration of secretory component (SC) in tracheal aspirate samples is less altered by changes in alveolar-capillary permeability and thus is a more reliable reference standard than albumin for the measurement of other components obtained by saline lavage in preterm infants.

METHODS

A total of 1229 tracheal aspirate and 1530 blood samples were collected from 195 neonates to evaluate the effects of advancing postnatal and gestational age, resolution of acute respiratory distress syndrome (RDS), steroid therapy for chronic lung disease, and acute sepsis on tracheal aspirate SC and albumin levels. The tracheal aspirate and blood samples were analyzed by enzyme-linked immunosorbent assay techniques for SC and albumin concentrations.

RESULTS

The mean values for the concentrations of aspirate and plasma SC did not vary significantly during an 8-week study period (n = 100) and did not vary with either gestational age (23 to 36 weeks) or postnatal age. Albumin concentration significantly decreased in aspirate samples from 1.67 +/- 0.77 mg/dl at week 1 to 0.41 +/- 0.21 mg/dl at week 8 (p < 0.001), whereas serum levels increased from 2.65 +/- 0.36 to 2.99 +/- 0.54 gm/dl (p < 0.001), suggesting a decrease in alveolar-capillary leakage with advancing postnatal age. The concentration of SC in aspirate samples from 51 infants who received dexamethasone remained constant during the first week of therapy, whereas the concentration of albumin decreased from 1.33 +/- 0.91 mg/dl at the initiation of therapy to 0.51 +/- 0.34 mg/dl on treatment day 7 (p < 0.001). The onset of sepsis (n = 40) was not accompanied by a significant change in either aspirate SC or albumin levels. However, in infants who had a deterioration in respiratory status concomitant with the onset of sepsis (n = 10), the levels of aspirate albumin increased whereas serum levels decreased (p < 0.001), suggesting an increase in alveolar-capillary leakage; the levels of aspirate SC remained unaltered.

CONCLUSIONS

Secretory component may serve as a more valid reference protein for the standardization of tracheal aspirate collection in preterm infants during evaluation of changes in inflammatory mediators in disease states and therapeutic interventions that alter alveolar-capillary integrity.

Cellular location and temporal expression of the Plasmodium falciparum sexual stage antigen Pfs16

The temporal expression during gametogenesis and the cellular location of the sexual stage specific protein Pfs16, a putative integral membrane protein of Plasmodium falciparum, was investigated using two monoclonal antibodies, 2G7 and 93A3A2. Using sorbitol synchronised, in vitro gametocyte cultures along with immunofluorescence assays, the time at which Pfs16 is first expressed during gametogenesis has been estimated to 35 hours post merozoite invasion. By immunofluorescence assays on thin blood smears monoclonal antibodies specific for Pfs16 react strongly with the gametocyte and also with vesicles within the red blood cell cytoplasm, many of which connect with the gametocyte cell. Purification of parasitophorous vacuole membranes from mature and immature gametocytes and immunoelectron microscopy on gametocytes during gametogenesis have allowed us to locate Pfs16 to the parasitophorous vacuole membrane. During gametogenesis this membrane is shed along with the red blood cell membrane. Immunofluorescence assays and immunoelectron microscopy studies of emerged gametes indicate that in a minority of cases the parasitophorous vacuole membrane along with Pfs16 can be retained to some extent on the gamete surface.

Strain increases airway smooth muscle cell proliferation

Airway smooth muscle (ASM) cell hyperplasia is a common finding in lung diseases in which increased transpulmonary pressure is necessary for adequate ventilation. The extent to which mechanical deformation of ASM cells contributes to the observed hyperplastic changes has not been addressed. To determine if cyclic stretch alters ASM cell proliferation and protein content in vitro, canine ASM cells were cultured on collagen-coated silastic membranes, subjected to a stretch-relaxation regimen, and compared with cultured cells on a rocking platform or with control (unmanipulated) cells. During the log phase of cell growth, cyclic stretch resulted in increased cell numbers (P < 0.001). Incorporation of [3H]thymidine ([3H]TdR) was assessed after 5 or 14 days in culture during 12-h pulse in stretched, rocked, and control cells. Incorporation of [3H]TdR per cell was elevated in stretched cells when compared with either rocked or control cells at 5 days but not 14 days. Total cellular protein content per well determined after cells had reached confluence was greater in stretched cells than in the controls (74.2 +/- 7.9 stretched versus 49.1 +/- 5.6 control versus 51.1 +/- 6.5 rocker; microgram/10(5) cells; P < 0.05). Transmission electron microscopic observations of stretched cells suggested increased concentrations of myofilaments compared with control cells. These observations suggest that stretch may contribute to increased ASM hyperplasia and airway resistance.

Hyperoxic exposure of developing rat lung decreases tropoelastin mRNA levels that rebound postexposure

These studies were undertaken to determine whether tropoelastin message expression in lung parenchymal tissue is altered in rats reared in an hyperoxic environment during the period of time that alveolar septation normally occurs. Rat pups were exposed to > 95% oxygen from days 4 to 14 and killed during the exposure and recovery periods. Results of in situ hybridizations indicated a delay in peak tropoelastin (TE) message levels in oxygen-exposed rats vs. controls, day 16 vs. day 11, respectively. In addition, lung parenchymal TE mRNA levels in the oxygen-exposed pups remained elevated through day 23, 1 wk after TE mRNA levels had decreased in controls. These observations suggest that the regulatory control of elastin synthesis during lung alveolar septation is altered by hyperoxic exposure. In a separate experiment, rat pups were exposed to > 95% oxygen during the period of alveolarization and followed for 4 wk postexposure. Pulmonary function measurements were conducted to determine whether lung function was altered postexposure and, if so, whether recovery occurred. We also used stereological techniques to quantitate the total length of lung parenchymal elastic fibers to determine whether elastic fiber content in the oxygen-exposed pups was restored to normal levels during the month postexposure. Although the total length of elastic fibers in lung parenchyma was found to be greater in oxygen-exposed than control pups from postnatal days 22 to 41, pressure-volume curves indicated that lungs of the oxygen-exposed pups tended to be more compliant than controls, suggesting that abnormal elastic fiber assembly might have been a contributing factor.

Effect of dexamethasone therapy on fibronectin and albumin levels in lung secretions of infants with bronchopulmonary dysplasia

The influence of dexamethasone on levels of total fibronectin (tFn), cellular fibronectin (cFn), plasma fibronectin (pFn), and albumin in lung secretions was determined in tracheal aspirate samples collected from 45 infants with bronchopulmonary dysplasia during a 6-week course of dexamethasone therapy. Secretory component for IgA (SC) was used as a reference protein. Thirty-seven infants (82%) survived and had their endotracheal tubes successfully removed. Corticosteroid therapy was associated with a significant decrease in the cFn/SC ratio. There was also a significant decrease in albumin/SC and pFn/SC ratios, suggesting decreased capillary permeability with corticosteroid therapy. Four of the remaining infants did not improve while receiving corticosteroids and died of respiratory failure at 3 to 8 weeks of age. In these "no response" infants, tFn/SC, cFn/SC, pFn/SC, and albumin/SC ratios when corticosteroid therapy was initiated were threefold to fourfold greater (p < 0.01) than ratios in survivors. Another group of four infants initially responded to corticosteroids but subsequently died with severe pulmonary cystic degeneration at 4 to 6 months of age; in these infants, tracheal aspirate tFn/SC, cFn/SC, and albumin/SC ratios were significantly lower than in survivors and remained unchanged during corticosteroid therapy. The decrease in the concentrations of plasma fibronectin and albumin in tracheal aspirate samples from the survivors suggests that the rapid clinical improvement seen in infants with bronchopulmonary dysplasia after the initiation of dexamethasone therapy is due in part to improvement in the integrity of the alveolar-capillary barrier. In addition, the decrease in the aspirate levels of cFn suggests the potential for corticosteroids to limit pulmonary fibrosis in the surviving infants. The depressed levels of fibronectin observed in the infants with severe cystic lung disease may represent an impaired healing response to lung injury.

Risk factors for the degradation of lung elastic fibers in the ventilated neonate. Implications for impaired lung development in bronchopulmonary dysplasia

In order to evaluate the risk for proteolytic destruction of lung parenchymal elastic fibers in ventilated premature infants, the concentrations of elastase were determined in tracheal aspirates of 65 infants from whom we obtained a total of 327 sequential samples. Elastase was detected at least once in 39 of the 65 infants studied. Eleven of these infants were ventilated with greater than 60% oxygen for greater than 5 days. In 19 infants, the presence of elastase was associated with positive bacterial and/or viral cultures and/or elevated ratios (greater than 0.22) of immature neutrophils to total neutrophils. Elastase was not detected in the lung secretions of 26 infants ventilated with greater than 60% oxygen for less than 3 days, suggesting minimal risk for elastic fiber destruction in the intubated infant who neither has pneumonia nor requires prolonged hyperoxic ventilation. The risk for elastic fiber destruction was further evaluated by analyzing sequential urine and tracheal aspirate samples for the presence of an elastolytic degradation product of elastin (desmosine). The biochemical data indicated a potential risk for proteolytic destruction of elastic fibers in association with infection and/or prolonged hyperoxic exposure. In addition, autopsy specimens obtained from three of the infants revealed structurally abnormal lung parenchymal elastic fibers. Because elastic fibers are believed to provide the structural support for alveolar septal development, proteolytic degradation of these fibers may be a significant factor in the impaired lung development that occurs in infants with bronchopulmonary dysplasia.

Immunofluorescence studies of lung tissue in cystic fibrosis

Previous studies have suggested that immune mechanisms contribute to lung injury in cystic fibrosis (CF); however, there have been no comprehensive studies of immunofluorescent staining patterns in CF lung tissue. We performed immunofluorescence (IF) studies for immunoglobulins, C3, and fibrinogen on autopsy frozen lung tissue from 21 CF patients. Results were compared with lung findings in patients without CF. In CF-derived lung tissue fibrinogen was ubiquitous along the alveolar wall, alveolar space, and interstitium. Free immunoglobulin G (IgG) and IgA coated the alveolar surface segmentally in 14 and 6 cases, respectively. Unequivocal interstitial deposits were infrequent and IgM was present in blood vessels in one patient only. Intra-alveolar and interstitial inflammatory cells demonstrated cytoplasmic IgG, IgA, and IgM, respectively, in 18, 14, and 6 patients. C3 was seen only segmentally along the alveolar wall in two patients and in blood vessels in one. Antinuclear antibody (ANA) staining of interstitial cells for C3 and immunoglobulins was seen in five patients, four of whom had interstitial pneumonitis. Insignificant amounts of alveolar or interstitial fibrinogen and immunoglobulins in inflammatory cells were seen in controls in the absence of lung inflammation. The IF patterns were similar in the inflammatory lesions of CF and control specimens. The IF patterns observed in CF lung tissue are consistent with nonspecific vascular leakage and chronic inflammation with little evidence of immune complex deposition in the interstitium or blood vessels. This study confirms previous reports of ANA activity in CF patients, although the significance of this finding is unknown.

Elevation of fibronectin levels in lung secretions of infants with respiratory distress syndrome and development of bronchopulmonary dysplasia

To determine whether the level of fibronectin in lung secretions correlates with the severity of lung injury or with the development of bronchopulmonary dysplasia, or both, serial tracheal aspirate samples were collected from 32 preterm infants with severe respiratory distress syndrome. Levels of total fibronectin, cellular fibronectin, plasma fibronectin, albumin, and secretory component of IgA (SC) were determined for the first 1 to 2 weeks of life in the 14 infants who recovered without pulmonary sequelae, and for weeks 1 to 4 in the 18 infants in whom bronchopulmonary dysplasia developed. Secretory component was chosen as the reference protein because its concentration in lung secretions is minimally influenced by capillary leak and does not vary with gestational or postnatal age. Albumin/SC and plasma fibronectin/SC ratios in tracheal aspirates were significantly higher (p less than 0.05) during the first 2 weeks of life in infants in whom bronchopulmonary dysplasia developed, suggesting greater capillary permeability in these infants. Cellular fibronectin/SC ratios in aspirates from infants with bronchopulmonary dysplasia were also significantly higher in the first 2 weeks, 9.0 +/- 1.7 and 7.4 +/- 2.0 micrograms/microgram SC in weeks 1 and 2, respectively, in comparison with values from infants without bronchopulmonary dysplasia, 1.6 +/- 0.4 and 1.1 +/- 0.8 micrograms/microgram SC (p less than 0.01), suggesting increased synthesis of fibronectin in the lungs of infants with subsequent bronchopulmonary dysplasia. Elevated levels of both plasma and cellular fibronectin in tracheal aspirate samples may provide an early index of the severity of lung injury in infants with severe respiratory distress syndrome.

Developmental changes in tropoelastin mRNA levels in rat lung: evaluation by in situ hybridization

Alveolarization of the immature lung is thought to be influenced by the presence of elastic fibers that could provide structural support for developing septa. Although morphometric studies have established that alveolar septal development occurs from days 4 to 13 in the neonatal rat, the precise time period over which elastin synthesis occurs has proved difficult to determine. We have evaluated the usefulness of in situ hybridization techniques to follow tropoelastin message expression in parenchymal tissue, small vessels, and bronchioles in the developing rat lung from days 4 through 18. This method proved to be sufficiently sensitive to detect differences in rates of tropoelastin message expression from days 4 through 18 (P less than 0.0001). Peak tropoelastin message expression was observed in the small vessels on day 4 and in parenchymal tissue on days 9 through 11. Because the time course of tropoelastin message expression in small vessels differs from that in parenchymal tissue, the use of lung extracts to analyze rates of tropoelastin synthesis in the developing lung may be in error.

A stage specific gene expressed at the onset of gametocytogenesis in Plasmodium falciparum

The gene encoding the gametocyte specific cytoplasmic protein Pfg27/25 of the human malaria parasite Plasmodium falciparum has been cloned. The gene encodes a highly hydrophilic non-repetitive protein which does not share obvious homologies with other polypeptides. The stage specificity of Pfg27/25 is controlled at the stage of the production of stable mRNA, which is detectable only in the sexual stages of the parasite, and contains long additional sequences outside the Pfg27/25 coding region. As the activation of Pfg27/25 gene expression occurs at an early stage of gametocytogenesis, the study of its regulation might provide information on the molecular events occurring after the parasite commitment to sexual differentiation and at the beginning of gametocyte formation.

A morphometric quantitation of developmental changes in elastic fibers in rat lung parenchyma: variability with lung region and postnatal age

Elastin has long been thought to play a pivotal role in alveolar septal development by providing the structural framework around which new alveoli develop in the immature lung. This theory was derived from observations that the dramatic increase in lung elastin and alveolar septal development occurred during the same time period, days 4 to 13 in the rat. Using stereologic techniques, we evaluated volume density of respiratory tissue in parenchyma and total length of parenchymal elastic fibers in the lungs of neonatal rats ranging in age from 4 to 26 days. Lung tissue was obtained from each of the four right lung lobes and from the upper, middle, and lower regions of the left lung. When changes in these two parameters in the lung as a whole were considered by averaging values for each of the seven regions, a continuous increase was observed in both the volume of parenchymal tissue in parenchyma and the total length of elastic fibers from days 4 to 22. A significant correlation was found between the volume of respiratory tissue in parenchyma and the length of parenchymal elastic fibers from days 4 to 26, supporting the existing theory that a causal relationship exists between these two parameters. A comparison of the ratios of elastic fiber length to volume density of respiratory tissue in parenchyma (Lv/Vrp) from each of the seven lung regions sampled indicated a significant variability in Lv/Vrp within different regions of the same lung. In addition, the effects of postnatal age and lung region on Lv/Vrp were interdependent; the lung regions that differed with respect to the length density of elastic fibers varied with postnatal age.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphometric analysis of the lung in bronchopulmonary dysplasia

We studied lung development in children with or without bronchopulmonary dysplasia (BPD) using light microscopic morphometry and thick lung sections stained for elastic fibers. One lung was obtained at autopsy from each of eight patients with BPD (ages, 2 to 28 months) and six children (ages, 5 days to 51 months) who died without lung disease. Patients with BPD demonstrated severe somatic growth retardation and had reduced lung volumes with abnormal lobar volume proportions. In the central bronchi mean volume proportion of glands and smooth muscle was increased in BPD. Bronchiolar density was also increased, but it tended to normalize with advancing age. Mean bronchiolar diameter was slightly smaller in BPD, and bronchiolar smooth muscle hypertrophy was a constant histologic feature. The most striking change, however, was noted in alveolar structure and development. Total alveolar number was severely decreased in patients with BPD compared with that in control subjects, and there was little evidence of compensatory alveolar development with increasing age. Lung internal surface area was correspondingly reduced, and mean linear intercept was increased. Sections stained for elastic tissue demonstrated in the patients with BPD a simplified acinar structure with thickened, tortuous, and irregularly distributed alveolar elastic fibers. We conclude that in severe, fatal BPD there is marked impairment of lung development with alveolar hypoplasia and reduced internal surface area. In addition, bronchial and bronchiolar smooth muscle hypertrophy and bronchial gland hyperplasia may be important contributing factors to airflow limitation.

Commitment of the malaria parasite Plasmodium falciparum to sexual and asexual development

Blood-stage malaria parasites in the vertebrate host can develop either into the asexual, multiplying forms, called schizonts, or into gametocytes, the sexual stages of the parasite. In the present work we studied the differentiation into asexual parasites or gametocytes of the progeny of single, isolated schizonts of the clone 3D7A of Plasmodium falciparum, using monoclonal antibodies specific for the sexual or asexual stages of the parasite. We observed that schizonts obtained from a continuous culture undergoing serial cycles of growth and dilution with fresh red blood cells produced either only gametocytes or only asexual parasites, showing a high degree of commitment to one or the other developmental pathway. The relative proportion of schizonts which produced gametocytes was very low at low parasite densities in culture, while at high parasite densities a much greater proportion of schizonts produced gametocytes. Nevertheless, at both low and high parasite densities individual schizonts were almost always fully committed to producing only gametocytes or only asexual parasites.

Changes in lung elastic fiber structure and concentration associated with hyperoxic exposure in the developing rat lung

Prolonged hyperoxic exposure is associated with impaired alveolarization of the lung in both the rat and the human neonate. Elastin is currently thought to play a pivotal role in the alveolarization of the lung by providing the structural framework around which new alveoli will develop. Previous studies in both the rat and the human neonate have demonstrated a risk for proteolytic destruction of lung elastin associated with prolonged hyperoxic exposure. The present study was undertaken to determine whether continuous exposure to 100% oxygen during the period of alveolar development in the rat (Days 4 to 13) would alter lung elastin. Parenchymal lung elastic fiber length, volume density of parenchyma, mean linear intercept, and internal surface area were quantitated using morphometric techniques, and the values were compared in control, oxygen-exposed, and malnourished rat pups. Stereologic measurements indicated that total elastic fiber length was significantly greater in lungs of control pups than in lungs of either the oxygen-exposed or the malnourished pups. Examination of sections of lung tissue 20 to 30 microns thick indicated altered elastic fiber structure and numerous alveolar fenestrae only in the hyperoxic pups. The results of these studies demonstrated that hyperoxic exposure during alveolarization alters both total length and structure of lung elastic fibers and suggest that impaired lung development might be due in part to these observed changes.

The pathologic characteristics of interstitial pneumonia cystic fibrosis. A retrospective autopsy study

Interstitial pneumonia is a poorly understood variant of lung injury in patients with cystic fibrosis (CF). The authors identified prominent interstitial pneumonia (defined as an inflammatory reaction predominantly involving alveolar septa) in 9 of 43 autopsied patients with CF. Lungs from these nine were studied by light microscopy to determine the histopathologic features, clinicopathologic correlates, and potential causes of CF-associated interstitial pneumonia. Two histologic variants were identified, alveoloseptal (in which the inflammatory reaction was confined to the alveolar wall) and organizing (in which intraalveolar granulation tissue was present in addition to septal inflammation), which respectively affected four and five patients. Cholesterol deposits and capillary proliferation were prominent associated features in some patients. Interstitial pneumonia was not diagnosed antemortem and was identified on chest roentgenogram in only two patients. There were no distinctive clinical features associated with different histologic subtypes, nor did histologic or clinical data identify a specific cause(s) of interstitial pneumonia. The authors conclude that CF-associated interstitial pneumonia, although usually an incidental finding at autopsy, may potentially contribute to respiratory impairment and death. Although there are multiple possible causes of interstitial lung injury associated with CF, the authors were unable to identify, with certainty, the pathogenesis of interstitial pneumonia in any patient in this study.

Pseudomonas cepacia-associated pneumonia in cystic fibrosis. Relation of clinical features to histopathologic patterns of pneumonia

We studied lungs at autopsy from 40 patients with cystic fibrosis (CF) to determine the structural and clinicopathologic features of pneumonia associated with Pseudomonas cepacia respiratory tract colonization. Three clinical groups were identified: group A included 11 patients exhibiting a fulminant course following P cepacia colonization; group B included 20 patients who declined slowly following colonization; and group C included nine patients without P cepacia colonization. Acute pneumonia occurred in all groups but was most extensive and necrotizing in group A. Chronic lobular pneumonia involved all groups equally, whereas interstitial pneumonia predominated in group B. Diffuse alveolar damage occurred infrequently in all groups. Combinations of structural patterns were frequently seen. We conclude that, although there is great overlap in the structural appearance of pneumonia among patients with CF with different bacterial colonization histories, the evidence suggests that P cepacia is a cause of necrotizing pneumonia in some patients. Factors that predispose to this fulminant lung infection are poorly understood.

Impaired surface membrane expression of C3bi but not C3b receptors on neonatal neutrophils

Because increased complement receptor expression is necessary for optimal function of adult neutrophils, we tested the hypothesis that the increased susceptibility of neonates to infection might be due to an impaired ability of neonatal neutrophils to increase expression of complement receptors in response to chemotactic stimuli. We used monoclonal antibodies and flow cytometry to compare surface expression of the receptors for the complement components C3b (CR1) and C3bi (CR3) on adult and neonatal cord blood neutrophils (PMNs). We also compared receptor expression on PMNs from infants delivered by cesarean section without labor versus infants delivered vaginally. Expression of both CR1 and CR3 was minimal on resting adult and neonatal PMNs maintained at 0 degrees C. There was a modest increase in expression of both receptors when PMNs were warmed to 37 degrees C. This increase was similar on adult and neonatal cells, both unfractionated in whole blood and after isolation with Percoll density centrifugation, with one exception. Expression of CR1 was greater on isolated PMNs from vaginally delivered infants versus adults when the cells were warmed to 37 degrees C. This difference was not observed with cells from infants delivered by cesarean section without labor, suggesting this modest increase in receptor expression may be due to factors associated with labor. When isolated cells were stimulated with either N-formyl-methionyl-leucyl-phenylalanine or zymosan-activated serum, expression of CR1 increased to the same extent in both neonatal and adult PMNs. In contrast, maximal CR3 expression on cord PMNs stimulated with N-formyl-methionyl-leucyl-phenylalanine or zymosan-activated serum was only 75% of the adult values.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered urinary excretion of elastin cross-links in premature infants who develop bronchopulmonary dysplasia

In order to determine whether elastin degradation is increased in infants whose respiratory insufficiency requires ventilation with high concentrations of O2, we quantitated, by amino acid analysis, the elastin degradation products (desmosines) excreted in the urine of 14 premature male infants during the first 3 wk of life. Eight of these infants, the "low-O2" infants, did not have severe lung disease and did not require more than 40% O2 beyond the first 8 h of life. The other 6 infants, selected retrospectively because they developed bronchopulmonary dysplasia (BPD), were ventilated with more than 60% O2 for at least the first 72 h of life. The pattern of desmosine excretion observed in infants who developed BPD differed significantly (p less than 0.05) from the excretion pattern seen in "low-O2" infants during the first 3 wk of life. At the end of the first week of life, desmosine excretion was significantly greater (p less than 0.05) in the infants who later developed BPD than in the "low-O2" infants without severe lung disease. From Days 7-9 to 20-22, desmosine excretion increased in the "low-O2" infants from 6.9 +/- 1.7 micrograms/kg to 9.0 +/- 3.5 micrograms/kg. In contrast, desmosine excretion did not remain elevated in the BPD infants, decreasing from 10.6 +/- 2.2 micrograms/kg to 6.1 +/- 2.9 micrograms/kg during the same period. In the BPD infants, elevated desmosine excretion through Day 9 is likely to reflect lung injury, whereas decreased desmosine excretion beyond Day 9 suggests that elastin synthesis and turnover is impaired, possibly as a result of nutritional deficiencies.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentrations of alpha 1-proteinase inhibitor and alpha 2-macroglobulin in serum and lung secretions of intubated infants

In order to determine the relative importance of the two proteinase inhibitors, alpha 1-proteinase inhibitor (alpha 1 PI) and alpha 2-macroglobulin (alpha 2M), in defending the infant lung against proteolytic attack, we measured concentrations of alpha 1PI and alpha 2M in both serum and lung secretions of infants intubated for respiratory insufficiency. In addition, we compared the concentration of each of the proteinase inhibitors in lung secretions with the serum concentrations of the proteinase inhibitor on the same day. Serum and secretions of all infants contained quantifiable levels of alpha 1PI. All serum samples had measurable amounts of alpha 2M. Ninety-two percent of the infants and 78% of all secretion samples tested contained alpha 2M. Molar ratios of alpha 1PI/albumin did not change as a function of gestational age in either serum or secretions. Serum alpha 2M/albumin also remained unchanged, but in lung secretions alpha 2M/albumin increased significantly with gestational age. With increasing postnatal age up to 44 days, mean levels of serum alpha 1PI, alpha 1PI/albumin, alpha 2M and alpha 2M/albumin increased. There was a greater increase in serum alpha 2M than in alpha 1PI as evidence by a decreasing molar ratio of alpha 1PI/alpha 2M with increasing postnatal age. In lung secretions, only alpha 1PI/albumin increased with postnatal age. Mean values for the molar ratio of alpha 1PI/alpha 2M in lung secretions ranged from 17 at 1-5 d to 22 at 11-44 d compared with the ratio of 200 reported for healthy adults (7).

Effects of two types of motor practice on stuttering adaptation

The present study identifies and compares the effects of two types of motor practice on stuttering adaptation. The study was designed to determine if whispered reading practice affects stuttering adaptation, and if practice in reading aloud is superior to whispered reading in promoting adaptation. In a control condition, eight stutterers read one of two matched passages aloud five times in succession. In an experimental condition, the remaining passage was read aloud on the first and fifth trials, and was read in a whisper on Trials 2, 3, and 4. The results indicated that (1) the stutterers' adaptation in the control condition was similar to the typical course of adaptation, (2) the three intervening whispered readings in the experimental condition neither inhibited nor facilitated adaptation, and (3) practice in reading aloud was superior to whispered practice in promoting stuttering adaptation. It was concluded that whispered reading practice does not facilitate stuttering adaptation when the measurement of that process requires reading aloud. Traditionally, adaptation has been measured only during reading done aloud. Consequently, practice in reading aloud has the greatest positive influence on the adaptation process.