A gutsy performance: the potential for supplementation of short-chain fatty acids to benefit athletic health, exercise performance, and recovery

The gut microbiome is known to play an important role in the day-to-day physiology and health of the human host. It is, therefore, not surprising that there is interest surrounding the gut microbiome and its potential to benefit athletic health and performance. This has, in part, been driven by the consideration that gut bacterial by-products (i.e. metabolic waste) could be harnessed by the host and utilised for a beneficial outcome. The concept of harnessing bacterial metabolites as beneficial health modulators has developed the theory of leveraging short-chain fatty acids (SCFAs) as novel supplements for enhancing athletic performance. This review discusses the current literature investigating SCFA administration in cellular, animal, and human models, with the aim of linking the demonstrated physiological/biochemical mechanisms to potential exercise/athletic benefit. In addition, practical implications and factors relating to SCFA-supplementation in athletic populations are considered. The literature demonstrates a tangible rationale that SCFAs can have a positive impact on human physiology to afford benefits to the athletic population. These advantages include the capacity to improve respiratory immunity to combat elevated levels/severity of upper respiratory tract infections often reported in athletes; the blunting of pro-inflammatory and pro-fibrotic pathways to aid in exercise recovery; and the role of SCFAs as usable energy sources and metabolism modulators to fuel exercise and improve performance and/or endurance capacity. However, there is currently minimal research completed in human participants and thus further investigations into the direct benefit of SCFAs in exercise performance and/or recovery-based studies are required.

A survey of training in pediatric flexible bronchoscopy

OBJECTIVE

There is currently no evidence-based method for defining competency in pediatric flexible bronchoscopy (FB). Based on expert opinion, guidelines using numbers of procedures have been published in defining competency for pediatric FB. The purpose of this study was to formally survey the opinion of USA pediatric pulmonology training directors about the assessment of competency and training experiences in pediatric FB in their programs.

METHODS

An Internet-based Survey Monkey™ of the Pediatric Pulmonary Training Directors Association (PEPTDA) was administered 10/12/10 through 11/1/10 with a supplemental survey 6/1/11-6/30/11.

RESULTS

This survey of US pediatric pulmonology training directors about competency and training in pediatric FB showed that a majority (86%) felt there was a minimum threshold of procedures for developing competency that could be defined, with a median of 50 and an average of 56.4 (SD = 33.0). The actual number of FBs performed by fellows during their 3-year fellowship averaged 89.4 (SD = 45.3) with a range of 10-200. The survey also revealed a variety of teaching techniques used for FB, including simulation technology. Finally many differences were reported in skill assessment, locations for performance of FB, and the range of underlying indications and patient populations. The apprenticeship model is the predominant method of learning FB in the surveyed programs.

CONCLUSIONS

A majority of US pediatric pulmonology training directors felt that a minimum number of procedures could be defined for developing competency in pediatric FB. There was variability in the numbers of procedures performed, training techniques and assessment, and application of FB. This survey represents an initial step in assessing training and defining competency in pediatric FB.

BOLD-fMRI of PTZ-induced seizures in rats

PURPOSE

To develop a non-invasive method for exploring seizure initiation and propagation in the brain of intact experimental animals.

METHODS

We have developed and applied a model-independent statistical method--Hierarchical Cluster Analysis (HCA)--for analyzing BOLD-fMRI data following administration of pentylenetetrazol (PTZ) to intact rats. HCA clusters voxels into groups that share similar time courses and magnitudes of signal change, without any assumptions about when and/or where the seizure begins.

RESULTS

Epileptiform spiking activity was monitored by EEG (outside the magnet) following intravenous PTZ (IV-PTZ; n=4) or intraperitoneal PTZ administration (IP-PTZ; n=5). Onset of cortical spiking first occurred at 29+/-16 s (IV-PTZ) and 147+/-29 s (IP-PTZ) following drug delivery. HCA of fMRI data following IV-PTZ (n=4) demonstrated a single dominant cluster, involving the majority of the brain and first activating at 27+/-23s. In contrast, IP-PTZ produced multiple, relatively small, clusters with heterogeneous time courses that varied markedly across animals (n=5); activation of the first cluster (involving cortex) occurred at 130+/-59 s. With both routes of PTZ administration, the timing of the fMRI signal increase correlated with onset of EEG spiking.

CONCLUSIONS

These experiments demonstrate that fMRI activity associated with seizure activity can be analyzed with a model-independent statistical method. HCA indicated that seizure initiation in the IV- and IP-PTZ models involves multiple regions of sensitivity that vary with route of drug administration and that show significant variability across animal subjects. Even given this heterogeneity, fMRI shows clear differences that are not apparent with typical EEG monitoring procedures, in the activation patterns between IV and IP-PTZ models. These results suggest that fMRI can be used to assess different models and patterns of seizure activation.

Geographical variations in the epidemiology of bacterial sexually transmitted infections in Manitoba, Canada

Feasible epidemiological approaches are required to make a better assessment of the stage of an epidemic and to monitor its transition through various phases. Application of the Lorenz curve and Gini coefficient to summarise the inequality in STD incidence rates between jurisdictions in Manitoba, Canada, was found to provide useful insights into the concentration of these epidemics over time and thus their transition through epidemic phases. Further exploration of the statistical properties of these and other indices of inequality and their potential application to STD epidemiology is warranted. New epidemiological tools are also required for better monitoring of the impact of prevention and control activities and to inform the content of these activities.

Acceleration of lung disease in children with cystic fibrosis after Pseudomonas aeruginosa acquisition

As part of the ongoing Wisconsin Cystic Fibrosis (CF) Neonatal Screening Project, we had the unique opportunity to study the longitudinal relationship between Pseudomonas aeruginosa (Pa) acquisition and infection and developing lung disease in children with CF. The primary objective was to determine whether acquisition of Pa was associated with a measurable change in the progression of lung disease. Two outcome measures were used to study 56 patients who were diagnosed through newborn screening: 1) Wisconsin additive chest radiograph score (WCXR), based on the average of scores from a pulmonologist and a radiologist, and 2) the highest forced expired volume in 1 sec (FEV(1))/forced vital capacity (FVC) ratio. We used two measures of Pa acquisition: 1) time of first positive protocol-determined oropharyngeal (with cough) culture, and 2) the magnitude of antibody titer detected by ELISA assays, using as antigen a crude cell lysate, purified exotoxin A, or an elastase toxoid prepared from three Pa strains. Other predictor variables included age, pancreatic status, height-for age, and weight-for-age-percentiles. The best regression model for predicting changes in the WCXR included time to first positive culture and antibody titer for Pa elastase. Prior to Pa acquisition, WCXR worsened by 0.45 points/year (P > 0.25); after Pa acquisition, the rate of worsening increased significantly (P < 0.001) to 1.40 points/year. Each antibody titer level (log base 2) increased the score by 0.48 points (P < 0.001). The best regression model for predicting change in the FEV(1)/FVC included only time to first positive culture. Prior to Pa acquisition, the FEV(1)/FVC ratio declined by 1.29%/year; after Pa infection, the rate of decrease significantly accelerated to 1.81%/year (P = 0.001). Our data show that Pa acquisition is associated with declining pulmonary status in children with CF, and that this effect is probably gradual rather than precipitous. Because these patients were diagnosed and treated aggressively, our estimates of the effects of Pa acquisition may be conservative. We also conclude that the WCXR appears to be more sensitive than FEV(1)/FVC in detecting early changes in lung disease associated with CF.

The stages of change for dietary fat and fruit and vegetable intake of patients at the outset of a cardiac rehabilitation program

PURPOSE

To determine the stages of change for dietary fat and fruit and vegetable intake of cardiac patients entering a rehabilitation program.

DESIGN

A cross-sectional study using a convenience sample of newly admitted cardiac rehabilitation patients.

SETTING

Department of Pulmonary and Cardiac Rehabilitation, Moses H. Cone Memorial Hospital, Greensboro, North Carolina.

SUBJECTS

Subjects (n = 226) were predominantly men, Caucasian, married, smokers with 9 to 12 years of education, and with primary diagnoses of coronary artery bypass graft.

MEASURES

Stages of change and food frequency questionnaires were completed by subjects upon admission to cardiac rehabilitation.

RESULTS

Subjects in action and maintenance stages for dietary fat reduction comprised 78.7% of the population. Subjects' percentage of energy from fat decreased linearly from the precontemplation stage (38.8%) to the maintenance stage (30.9%). Eighty-one percent of subjects were in precontemplation/contemplation for increasing fruit and vegetable intake. Daily servings of fruits and vegetables ranged from 2.6 for precontemplation to 5.1 for maintenance subjects. Age, body mass index (BMI), education, and family history for coronary disease were unrelated to stage of change for the dependent variables.

CONCLUSIONS

Patients were in different stages of change for two nutritional behaviors linked to the same disease. Results support the need to assess patients for food behaviors and apply different educational interventions for each food behavior.

The effect of employee job satisfaction on program participation rates in the Virginia WIC Program (Special Supplemental Nutrition Program for Women, Infants, and Children)

Many researchers have shown a link between employee job satisfaction and customer satisfaction in the private sector. Customer satisfaction is the end result of whether the particular service and/or a product meet the customer's needs. The purpose of this research project was to assess the level of employee job satisfaction in the Virginia WIC Program and to determine whether a correlation exists between the level of employee job satisfaction and program participation rates. The results of this study showed that high levels of employee job satisfaction were positively correlated to high program participation rates in the Virginia WIC Program.

The impact of customer focus on program participation rates in the Virginia WIC Program (Special Supplemental Nutrition Program for Women, Infants, and Children)

It has been shown in the for-profit sector (business, service, and manufacturing) that the success of an organization depends on its ability to satisfy customer requirements while eliminating waste and reducing costs. The purpose of this article was to examine the impact of current practices in customer focus on program participation rates in the Virginia WIC Program. The results of this study showed that the use of customer-focused strategies was correlated to program participation rates in the WIC Program. The mean data showed that teamwork and accessibility were at unsatisfactory levels in Virginia.

Sodium tetraborate effects on mortality and reproduction of Anastrepha suspensa (Diptera: Tephritidae)

When flies were treated with 0- 0.5% sodium tetraborate by feeding for 24 h, mortality in treatments was not different from controls. Fecundity and fertility were reduced by 0.5% sodium tetraborate. When flies were fed for 48 h, mortality of both males and females increased in the 0.5% sodium tetraborate treatment; oviposition was eliminated for 20 d after treatment. When treatment was extended to 168 h, 0.1% sodium tetraborate caused increased mortality and decreased fecundity and fertility. Fed for 168 h, 0.2 and 0.5% sodium tetraborate killed almost all flies within the 7-d treatment. Oviposition of survivors in 0.1 and 0.2% sodium tetraborate treatments was arrested for 20 d after treatment.

Wisconsin cystic fibrosis chest radiograph scoring system: validation and standardization for application to longitudinal studies

This study was designed to achieve a final modeling, validation, and standardization plan for the Wisconsin cystic fibrosis (CF) chest radiographic scoring system. Sixty chest radiographs were selected to reflect a range of severity of lung pathology in children with CF. Seven experienced volunteer raters (three radiologists and four pediatric pulmonologists) from five institutions were recruited to evaluate and score the films. Analysis of scores revealed that the subcomponents of the Wisconsin system showed considerable variation from rater to rater, but reliability assessment indicated satisfactory Cronbach's alpha coefficients (0.83-0.90) among the seven raters. It was found that an additive method of total score computation is significantly more reliable (P < 0.05) than either the original multiplicative model or the traditional Brasfield scoring system. Comparison of radiologists and pulmonologists revealed a marked, systematic difference in scoring with the former group being more conservative in interpretation of abnormalities than the pulmonologists, and some of the raters showing very limited sensitivity. Quantitative chest radiology applied to children with cystic fibrosis studied long-term in longitudinal research projects requires the careful use of sensitive scoring methods and careful selection and training of multiple raters. This is particularly important since pulmonologists and radiologists can differ systematically in interpreting/scoring abnormalities.

Total quality management in the delivery of public health services: a focus on North Carolina WIC programs

Principles of quality improvement have been successfully implemented in the for-profit sector of the United States economy. The purpose of this study is to test the use of quality improvement strategies including development of leadership skills, a focus on internal quality, ongoing training and staff development, and efficient use of resources in the delivery of services in the public sector. The emphasis of this study is strategies for improving the delivery of nutrition education and supplemental foods to high-risk women, infants, and children through a federally funded program called WIC.

Growth status in children with cystic fibrosis based on the National Cystic Fibrosis Patient Registry data: evaluation of various criteria used to identify malnutrition

OBJECTIVES

The objectives of this study were to determine growth status and to identify malnutrition with various anthropometric indicators in children with cystic fibrosis (CF) based on cross-sectional analysis of the 1993 National CF Patient Registry data.

METHODS

Heights and weights of 13,116 children with CF were evaluated with percentile, percent of reference median, Z-score, and percent ideal weight-for-height based on National Center for Health Statistics/Centers for Disease Control growth references. Malnutrition was defined by four criteria: (1) height-for-age <5th percentile ("stunting") or weight-for-age <5th percentile ("wasting") (2) height-for-age <90% of reference median or weight-for-age <80% of reference median, (3) height-for-age <5th percentile or percent ideal weight-for-height <85%, and (4) height-for-age <90% of reference median or weight-for-height <85% of reference median.

RESULTS

Mean and median height- and weight-for-age were found to be at the 30th and 20th percentiles in children with CF. Malnutrition (height- or weight-for-age <5th percentile) was particularly pronounced in infants (47%) and adolescents (34%) and patients with newly diagnosed CF (44%). A significant sex difference (p < 0.01) in the occurrence of stunting (height-for-age <5th percentile) was observed during adolescence: boys 11 to 14 years of age showed lower occurrence of stunting (19%) compared with girls (29%), whereas the opposite trend was observed at 15 to 18 years (34% in male patients vs 28% in female patients).

CONCLUSION

Twenty percent of all children in the 1993 National CF Patient Registry were <5th percentile for height- or weight-for-age. A significant discrepancy was found when different criteria were used to distinguish "stunting" versus "wasting" in malnourished children with CF.

The bridging bronchus. Successful diagnosis and repair

Anomalies of bronchial branching are infrequent and may be difficult to diagnose. The bridging bronchus is a rarely reported anomaly that may not be as sporadic as once thought. We describe an infant with respiratory distress whose right middle and lower lobes were supplied by a bridging bronchus arising from the left main bronchus. The airway anatomy was defined using flexible and rigid bronchoscopy and helical computed tomographic scanning, enabling successful surgical repair. We review current literature on the bridging bronchus as well as the possible embryological basis for this defect.

Differential effects of interleukin-2 and interleukin-4 on immunomodulatory role of platelet-activating factor in human B cells

Platelet-activating factor (PAF), a naturally occurring phospholipid cytokine, is a potent mediator of allergic and inflammatory reactions, as well as a modulator of immune responses. In the present study we showed that PAF is involved in early B-cell activation, as demonstrated by the increased cyclic AMP (cAMP) generation by PAF in a time- and dose-dependent manner in anti-mu antibody- plus B-cell growth factor-activated normal human peripheral blood B lymphocytes. PAF also regulated differentiation by causing a biphasic response on immunoglobulin M (IgM) production with an inhibitory signal generated at 10(-6) M and a stimulatory signal generated at 10(-8) to 10(-10) M. PAF enhanced IgA secretion. The regulation exerted by PAF was shown to be specific because the addition of the PAR antagonist CV-3988 abrogated these effects and the inactive form of PAF, lyso-PAF, induced neither cAMP generation nor immunoglobulin secretion in normal human B cells. Other cytokines, interleukin-2 (IL-2) and IL-4, potent mediators of the immune response, were unable to elicit a cAMP response in B cells. However, the addition of PAF (10(-6) M) with wither IL-2 or IL-4 enhanced cAMP production above the levels enhanced by the addition of PAF alone. IL-2 or IL-4, individually, stimulated IgM production, yet costimulation with PAF resulted in a differential effect between IL-2 and IL-4. PAF down-regulated the IL-4-induced IgM secretion, whereas the IL-2-induced IgM secretion was enhanced. The presence of CV-3988 returned all valued to those obtained with IL-2 or IL-4 alone, demonstrating the specificity of PAF. These data suggest that PAF is an important B-cell immunomodulator which can interact with other leukocyte cell mediators.

Wisconsin cystic fibrosis chest radiograph scoring system

A new clinical scoring system for patients with cystic fibrosis is needed because of recent advances in diagnosis and treatment which have changed the course of this disease. Chest radiograph scoring is the best objective measure of pulmonary disease for longitudinal studies beginning with infants; however, based on pilot studies, previous scoring systems are not sensitive enough in discriminating between degrees of mild lung disease. Therefore, a new radiographic scoring system was developed with the goal of achieving both sensitivity and reproducibility. This objective was pursued by applying multiattribute utility theory, using a panel of interpreters with expertise in cystic fibrosis radiology, and employing mathematical modeling techniques to weight the various components. The system was developed and validated in three phases including comparison to the Brasfield method of quantitative radiology. The data demonstrate that the new system can be applied reliably and conveniently to generate reproducible scores of pulmonary disease severity. Evaluation of the scores by four independent raters using chest radiographs from 61 patients at an average age of 8.37 years revealed good agreement with a .714 Kendall coefficient of concordance. Assessment of serial changes over time was performed using a group of 176 chest radiographs from 25 patients ranging from 4 weeks to 6 years old; this showed that the Wisconsin system generates score differences that are greater in magnitude with disease progression compared with the Brasfield method. Therefore, the new method is more sensitive to progression of mild disease and should be superior to prior radiographic scoring systems for evaluating therapies designed to modify the early course of disease. The Wisconsin system is designed to be useful in longitudinal clinical studies involving young children with cystic fibrosis and is capable to detecting progression from normality to mild lung disease.

Obstructive sleep apnea in Apert's and Pfeiffer's syndromes: more than a craniofacial abnormality

Nine acrocephalosyndactyly type I patients (Apert's syndrome) and three acrocephalosyndactyly type V patients (Pfeiffer's syndrome) were evaluated for the relative importance of upper and lower airway abnormalities in the generation of obstructive sleep apnea. All patients were found to have a combination of upper and lower abnormalities. The influence of lower pathology was greater in the infants, and the influence of upper airway, specifically pharyngeal, was greater in the adults. A comparison between preoperative and postoperative polysomnography revealed little improvement with standard craniofacial advancements. Furthermore, three patients are described who succumbed to pulmonary death despite tracheostomy. Conservative treatment with prone or lateral positioning and medical pulmonary regimens is advocated. Finally, the pathogenesis of this diffuse airway pathology is discussed.

Respiratory complications in children with spondyloepiphyseal dysplasia congenita

Mild respiratory distress at birth is a common occurrence in infants with spondyloepiphyseal dysplasia congenita (SEDC) while severe respiratory insufficiency and death have been reported only rarely. We describe three infants with SEDC who experienced severe respiratory complications and required tracheostomies. Two of these infants have also needed long-term continuous positive airway pressure to maintain adequate ventilation. The features and clinical course of these children are described, previous reports of respiratory complications in SEDC are summarized, mechanisms resulting in respiratory problems in SEDC are postulated, and comparison is made with mechanisms giving rise to respiratory risks in other skeletal dysplasias.

Rapid methylprednisolone clearance in a patient with cystic fibrosis

A pharmacokinetic investigation of administered corticosteroids was conducted in a 16-year-old girl with cystic fibrosis (CF). Equivalent doses of methylprednisolone were given orally and intravenously on consecutive days. Oral bioavailability was essentially 100 percent, ruling out impaired absorption. Drug half-life was shorter and both clearance and volume of distribution were greater in this patient than in normal young adults. From one patient it is impossible to conclude that this unusual disposition of corticosteroids is characteristic of CF. Given the interest in use of corticosteroids in this population, and the examples of other drugs with altered pharmacokinetics in patients with CF, further investigation is warranted.

Water vapour and temperature dynamics in the upper airways of normal and CF subjects

Water vapour partial pressure (PH2O) and temperature (T) were measured together, continuously, at the airway opening (either lips or nares) and at the oropharynx of human subjects with normal lungs or with cystic fibrosis (CF). No apparent differences in PH2O or T were found between normal and CF groups breathing ambient air (22 +/- 2 degrees C). During inspiration the relative humidity at the pharynx for nose breathing (95%) was higher than for mouth breathing (75%). For hot air breathing (48 +/- 2 degrees C), the PH2O and relative humidity of inspired gas at the pharynx was lower for the CF group than for the normal group. Also, the CF group had a higher airway surface temperature at the airway openings on inspiration. These data suggest that when the rate of evaporation is sufficiently high, the rate-limiting step may be water transport through the mucosal tissue and/or secretions. At least for the upper airways, this rate limitation is more evident for CF patients than for normal subjects.

Water vapour and temperature dynamics in the upper airways of normal and CF subjects

Water vapour partial pressure (PH2O) and temperature (T) were measured together, continuously, at the airway opening (either lips or nares) and at the oropharynx of human subjects with normal lungs or with cystic fibrosis (CF). No apparent differences in PH2O or T were found between normal and CF groups breathing ambient air (22 +/- 2 degrees C). During inspiration the relative humidity at the pharynx for nose breathing (95%) was higher than for mouth breathing (75%). For hot air breathing (48 +/- 2 degrees C), the PH2O and relative humidity of inspired gas at the pharynx was lower for the CF group than for the normal group. Also, the CF group had a higher airway surface temperature at the airway openings on inspiration. These data suggest that when the rate of evaporation is sufficiently high, the rate-limiting step may be water transport through the mucosal tissue and/or secretions. At least for the upper airways, this rate limitation is more evident for CF patients than for normal subjects.

Tracheomalacia and bronchomalacia associated with Larsen syndrome

Bronchomalacia has not previously been described in association with Larsen syndrome. In this article, three children with Larsen syndrome are reported. All three patients have tracheomalacia, and one of them has diffuse bronchomalacia diagnosed at flexible fiberoptic bronchoscopy. The patients' symptoms of airway obstruction include stridor, cyanosis, apnea, and recurrent pneumonias. Recognition of these abnormalities may allow the institution of supportive therapy.

Antibody to human lymphocyte actin regulates immunoglobulin secretion by an EBV-transformed human B-cell line

Antibody against actin isolated from a human EBV-transformed lymphoblastoid B-cell line exerted an inhibitory effect on in vitro IgM secretion by a different lymphoblastoid B-cell line, LA350. This effect was dose dependent showing from 24-40% inhibition at a dilution of 1:100 and 68-80% inhibition at a dilution of 1:50. This effect was noted in the absence of changes in either total cell count or [3H]-thymidine incorporation and was reversed by co-incubation with purified rabbit thymus actin (100 micrograms/ml) but not bovine serum albumin at the same concentration. These data demonstrate regulation of immunoglobulin synthesis by antibodies against human lymphocyte derived actin in a lymphoblastoid B-cell line.

Anti-rabbit thymus actin antibody inhibits proliferation of Epstein-Barr virus-transformed human B cell line LA350: augmentation by cyclic AMP

Antibody to actin isolated from the rabbit thymus gland exerted a dose-dependent inhibitory effect upon the proliferation of an Epstein-Barr virus-transformed human B cell line, LA350. Purified rabbit thymus actin specifically reversed the inhibitory effect of antibody by competing with surface actin on LA350. For example, LA350 proliferation at 48 hr was inhibited 90% at a 1:10 antibody dilution (p less than 0.001) but only 48% and 20% in the presence of 190 and 380 micrograms/ml of rabbit thymus actin, respectively (p less than 0.001 for reversal). Cyclic AMP augmented in a dose-related fashion the inhibitory effects of antibody, e.g., a 1:20 dilution of antibody inhibited 10, 19, 41, and 67% at 0.0, 0.5, 1.0, and 2.0 mM cAMP, respectively (p less than 0.001). We conclude that anti-actin antibody recognizes surface actin on a human B cell line and produces a functional inhibition of proliferation by a process that is augmented by cAMP.

Identification of L-cell growth stimulating antibody as anti-actin

Anti-L-cell antisera having potent cell growth stimulatory properties were shown by Western blotting to have predominant specificity toward a protein with a molecular weight of 42K which we identified as actin. Extractions of L cells, based upon the known insolubility of cytoskeletal proteins (including actin) in Triton X-100 and the solubility of actin in low ionic strength Ca2+ and ATP-containing buffer, led to actin-enriched preparations that retained immunoreactivity with the anti-L-cell antisera. The 42-kDa antigen binds to deoxyribonuclease I, has a pI = 5.2-5.4, and has an amino acid composition, including the presence of 3-methylhistidine, compatible with compositions determined for actins from other sources. Rabbit antiserum specific for this 42-kDa protein, isolated by SDS-PAGE, reproduced the cell growth stimulation by the anti-L-cell antisera and absorption of the antiserum with purified L-cell actin eliminated this stimulation. Moreover, these antibodies bind to the microfilaments of 3T3 fibroblasts. When purified actins were used as soluble antigen inhibitors of the immune reactivity of antiserum to 42-kDa protein with intact L cells, rabbit thymus actin competed with the surface molecules on L cells and reduced the stimulatory effect of the antiserum by 80% at an actin concentration of 150 micrograms/ml. Chicken muscle actin reduced the antibody stimulation effect by only 24% at the same protein concentration, and mouse muscle actin was ineffective as an inhibitor. The F(ab')2 fraction of anti-42K IgG was effective in stimulating L cells, thus documenting the immune nature of the actin-anti-42K interaction. We conclude that anti-actin antibodies, upon binding to actin-like cell surface determinants on L cells, stimulate cellular metabolism.

Cyclic AMP and theophylline enhance DNA synthesis in L cells stimulated with anti-actin IgG and [(IgG)2 protein A]2 complex by recruiting cells into S-phase

Surface binding of anti-actin IgG alone or in a Mr = 716 000 [(IgG)2 Protein A]2 complex results in a stimulation of DNA synthesis and cell growth in L cells. Cyclic-AMP (0.01-1.0 mM) added to such cell cultures augmented DNA synthesis as measured by incorporation of [3H]thymidine into DNA. Theophylline (0.1-1.0 mM), a phosphodiesterase inhibitor which prevents enzymatic breakdown of cAMP, had similar effects, but cGMP (0.01-1.0 microM) reversed the effects of cAMP and theophylline upon DNA synthesis. Analysis of the cell cycle by flow cytometry revealed that antibody produced a shift (7%) of cells from the G1-phase to the S-phase (DNA-synthetic) of the cell cycle at 72 hr of incubation. Addition of cAMP (0.5 mM) to cell cultures, however, produced significant shifts of antibody stimulated cells from G1-phase to S-phase at all time points measured, i.e., 24 (12%), 48 (22%), 72 hr (23%). Thus, antibody recruited cells into S-phase of the cell cycle and cAMP greatly augmented the effect. These observations suggest that the mechanism of activation of L cell growth by antibody to surface antigens involves a recruitment of cells into the DNA-synthetic phase and that the effect may be mediated by cAMP.

[(IgG)2 protein A]2 complex stimulates cytosine arabinoside incorporation into DNA and inhibits L cell proliferation

A Mr = 716 000 complex, [(IgG)2 Protein A]2, formed when Protein A is mixed with a molar excess of IgG anti-L cell antibody, augmented [3H]thymidine incorporation in DNA and growth of a murine transformed L cell line. It was also possible to augment the incorporation of [3H]cytosine arabinoside (2.3-fold) in DNA by the binding of this complex to L cells. A synergistic inhibition of L cell proliferation was produced using the complex and certain concentrations of cytosine arabinoside. By binding the complex to L cells, a 5-fold lower concentration of cytosine arabinoside (0.050 microgram/ml) was as effective in inhibiting cell replication as the higher dose of the drug (0.25 microgram/ml) with cells bound by IgG antibody alone, and a 20-fold lower concentration compared to the effects of the drug itself (1.0 microgram/ml). Addition of 10 microM thymidine to the complex permitted the use of an even lower dose of cytosine arabinoside (0.004 microgram/ml) for inhibition of cell growth. Thymidine caused this effect by producing an even greater incorporation of drug into the DNA of complex-stimulated cells. Thus, by stimulating the cell with the immune [(IgG)2 Protein A]2 complex it was possible to stimulate uptake of a chemotherapeutic nucleoside and selectively inhibit cell replication at non-toxic doses of nucleoside.

Heat acclimation in cystic fibrosis

Cystic fibrosis (CF) patients may be at risk for heat illness because of their high sweat chloride and sodium concentrations ([Cl-], [Na+]), but it is not known if they can heat acclimate. We studied 10 CF patients and 10 normal controls on 8 consecutive days of cycle exercise in the heat (37 degrees C dry bulb, 24-29 degrees C wet bulb). Both groups acclimated. CF peak rectal temperature (Tre) was 38.2 +/- 0.3 degrees C on day 1 and 37.8 +/- 0.4 degrees C on day 8 (P less than .005), and peak heart rates (HR) were 151 +/- 24 beats/min on day 1 and 136 +/- 22 beats/min on day 8 (P less than 0.025). Control temperature (T) and HR were similar. Controls decreased sweat [Cl-] from 37.2 +/- 14.6 meq/l on day 1 and to 24.9 +/- 10.6 meq/l on day 8 (P less than 0.005). CF sweat [Cl-] was significantly higher and did not change with acclimation (day 1, 71.1 +/- 20.9 meq/l; day 8, 72.6 +/- 21.6 meq/l, NS). Before and after acclimation, exercise-heat sessions resulted in significant decreases in serum [Cl-] in CF patients (104.5 +/- 4.6 to 101.3 +/- 4.4 meq/l on day 1, P less than 0.05; 103.5 +/- 5.1 to 99.7 +/- 4.2 meq/l on day 8, P less than 0.025) but not in controls. Serum [Cl-] was significantly lower in CF than control subjects at every measurement. Both groups had significant renal Na+ conservation after exercise on both days.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody to immunoselected L-cell antigens mimics stimulating activity of antibody to whole L cells

A heterogeneous IgG antibody raised in rabbits in response to injections of whole L cells was used to identify and select relevant antigens in a nonionic detergent extract of L cells prelabeled with [35S]methionine by means of immunoprecipitation and immunoaffinity chromatography. When analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the immunoprecipitate and immunoeluate contained far fewer protein bands than the whole cell extract but selectively retained a 42,000-MW protein species. In response to injections of the immunoprecipitate, rabbits produced a new antiserum which reacted predominantly with the 42,000-MW protein when reacted with L-cell proteins separated by sodium dodecyl sulfate-gel electrophoresis and transferred to nitrocellulose paper by the Western blot technique. The new antiserum (raised to the immunoprecipitate) and the original antiserum (raised to whole cells) were equipotent in stimulating calcium transport, phospholipid metabolism, and DNA synthesis in L cells. Binding of the IgG fractions of the two antisera displayed identical high affinity binding to L-cell surface antigens, with the same average association constant of 1.5 X 10(6) M-1. These studies have shown that an antiserum raised to whole L cells has a much narrower reactive spectrum with L-cell membrane antigens than might be imagined and has identified a 42,000-MW membrane protein as an important immunogen which itself elicits a potent immune response resulting in an antibody capable of mimicking the cell stimulatory properties of the original antiserum.

IgG-protein A complexes modulate thymidine incorporation into DNA of antibody and complement-stimulated cells

Incubation of protein A (PA) and molar excess of whole rabbit immune IgG in solution favored the formation of high m.w. complexes with the molecular formula of [(IgG)2(PA)]2, which enhanced the incorporation of [3H]thymidine ([3H]dThd) into DNA of L cells, especially in the presence of rabbit or human complement (C). In contrast, complexes with the molecular formula (IgG)(PA), formed by incubation of IgG with molar excess of PA, failed to enhance, or inhibited, the incorporation of [3H]dThd into cells treated with immune IgG alone or with C present, respectively. Concanavalin A (Con A), which is known to bind to critical exposed oligosaccharide structures present in the Fc region of IgG in the [(IgG)2(PA)]2 complexes, reversed the enhancement of [3H]dThd incorporation, and alpha-methyl mannoside, but not D-galactose, inhibited the Con A reversal. The [(IgG)2(PA)]2 complexes efficiently activated the C cascade, caused significantly higher levels of aggregation of cells, and increased the binding of immune IgG to the cells when compared to the (IgG)(PA) complexes. Both types of complexes, isolated by sucrose density ultracentrifugation, were precipitable in a radioimmunoassay with chicken anti-PA antibodies and were capable of binding to intact L cells.

IgG-protein A complexes modulate thymidine incorporation into DNA of antibody and complement-stimulated cells

Incubation of protein A (PA) and molar excess of whole rabbit immune IgG in solution favored the formation of high m.w. complexes with the molecular formula of [(IgG)2(PA)]2, which enhanced the incorporation of [3H]thymidine ([3H]dThd) into DNA of L cells, especially in the presence of rabbit or human complement (C). In contrast, complexes with the molecular formula (IgG)(PA), formed by incubation of IgG with molar excess of PA, failed to enhance, or inhibited, the incorporation of [3H]dThd into cells treated with immune IgG alone or with C present, respectively. Concanavalin A (Con A), which is known to bind to critical exposed oligosaccharide structures present in the Fc region of IgG in the [(IgG)2(PA)]2 complexes, reversed the enhancement of [3H]dThd incorporation, and alpha-methyl mannoside, but not D-galactose, inhibited the Con A reversal. The [(IgG)2(PA)]2 complexes efficiently activated the C cascade, caused significantly higher levels of aggregation of cells, and increased the binding of immune IgG to the cells when compared to the (IgG)(PA) complexes. Both types of complexes, isolated by sucrose density ultracentrifugation, were precipitable in a radioimmunoassay with chicken anti-PA antibodies and were capable of binding to intact L cells.

Modulation of metabolism of cytosine arabinoside in L cells by antibody and complement

Complement modulated the metabolic conversion of cytosine arabinoside into its nucleotide and nucleic acid derivatives in L cells by augmenting the biphasic effect (inhibitory/stimulatory) of anti-L cell antibody. Antibody in the absence of complement affected both the total cellular pool of cytosine arabinoside (containing the nucleotide and nucleic (DNA) acid derivatives) and the acid-insoluble pool (containing the DNA derivative). Addition of complement in high concentrations inhibited and, in low concentrations, stimulated the incorporation of cytosine arabinoside into DNA of antibody stimulated L cells. At the point of maximum stimulation of cytosine arabinoside incorporation into DNA, there was a pronounced decrease in the size of the total cellular pool with the result that 75% of the total pool of cytosine arabinoside was due to its incorporation into DNA. Simultaneous measurements upon cytosine arabinoside and thymidine or deoxycytidine metabolism were made; the effects of antibody and complement appeared to be quite similar with all three nucleosides, with the exception that all thymidine and deoxycytidine taken up into the cells was incorporated into DNA. Addition of exogenous thymidine (up to 100 microM produced the same enhanced incorporation of [3H]Ara-C and [14H]dCyd into control cells that was observed in antibody and complement stimulated cells. Measurement of deoxycytidine kinase activity in cell-free extracts of cell cultures stimulated by antibody, however, did not reveal enhanced enzymatic activity due to stimulated enzyme synthesis, but, rather indicated that antibody and complement altered the intracellular concentrations of nucleotides which affected the interaction of cytosine arabinoside with deoxycytidine kinase in intact cells.(ABSTRACT TRUNCATED AT 250 WORDS)