Chest wall motion in preterm infants using respiratory inductive plethysmography.

Preterm infant tidal breathing may be different from that of healthy full-term infants because of various features of the premature thorax. The purpose of this project was to describe chest wall motion in the preterm infant (gestational age <37 weeks) and compare it with chest wall motion data in a group of healthy, full-term infants. We wanted to use an objective bedside method for assessment with minimal disruption to the infant. The study population consisted of 61 preterm human infants whose mean(+/-sD) postconceptional age at time of study was 35.3+/-2.1 weeks. During the study, the infants were quietly awake in a prone position. Preterm infants had initially been admitted to a level III neonatal intensive care unit for acute management and had been transferred to a step-down area, where they were in stable condition for study. Data were collected with a semiquantitatively calibrated, noninvasive respiratory inductive plethysmograph. Mean(+/-SD) phase angle was significantly greater in preterm infants than in full-term infants (60.6+/-39.8 degrees versus 12.5+/-5.0 degrees, respectively, p < or = 0.0001). The laboured breathing index was significantly greater in preterm infants than in full-term infants (1.35+/-0.35 versus 1.01+/-0.01, respectively, p = 0.001). The ribcage contribution to breathing did not differ significantly between preterm and full-term infants (25.5+/-17.7% versus 36.3+/-14.4%, respectively, p = 0.11). These results indicate a significant increase in the degree of ribcage and abdomen asynchrony in the preterm subjects compared to the full-term infants. Plethysmography provided a time-efficient and objective method of assessing chest wall motion in this fragile population.

TGF-alpha-induced breakdown of stress fibers and degradation of tropomyosin in NRK cells is blocked by a proteasome inhibitor.

Treatment of NRK cells with TGF-alpha in the presence of serum initiates disassembly of cytoskeletal stress fibers and suppresses the synthesis of tropomyosin isoforms (TMs) 1, 2, and 3 but not TMs 4 and 5 (Cooper et al., Cancer Res. 47, 4493-4500, 1987). In order to determine how the loss of tropomyosin is induced and what role it plays in cytoskeletal disruption, the turnover of tropomyosin was studied in the presence of the transforming growth factor and protease inhibitors. Cells were pulse-labeled with [35S]methionine and chased in the absence or the presence of the growth factor. It was found that TMs 1, 2, and 3 are degraded at about twice the rate of TMs 4 and 5 in control cells and that the rate of degradation of TMs 1-3 is accelerated by the growth factors. Degradation of TMs in control and growth factor-treated cells is blocked by a membrane-permeable inhibitor of cysteine proteases (LLnL) that acts upon calpains and proteasomes, and the cells maintain a flattened shape with a normal complement of stress fibers. Application of inhibitors that block calpains but not proteasomes does not block TM degradation. Treatments (suspension culture or cytochalasin B) that disrupt stress fibers without application of the growth factors also accelerate TM degradation, suggesting that acceleration of TM degradation is a consequence of its release from stress fibers during their breakdown. The normally more rapid turnover of the TM isoforms 1-3 that are lost in the phenotypically transformed cells could serve to facilitate the cytoskeletal reorganization that follows the activation of signal transduction pathways by the transforming growth factors observed in this study or during other rearrangements of the cytoskeleton such as occur during cell migration or mitosis.

A pulmonary monitoring and treatment plan for children with Duchenne-type muscular dystrophies.

The Pulmonary Medicine Section of the Department of Pediatrics of the University of Arkansas for Medical Sciences has recently developed an association with the Muscular Dystrophy Association Clinic held at Arkansas Children's Hospital. The slowly progressive, insidious onset of pulmonary problems associated with Duchenne-type muscular dystrophies and other degenerative muscle disorders indicated a need for a aggressive monitoring and treatment plan for these children and their caregivers. We have developed a Respiratory Care Handbook for families with information on the pulmonary consequences of these diseases including pathophysiology, pulmonary function tests, respiratory treatments including mechanical ventilatory support, and anticipation and prevention of pulmonary crises. In addition, we have introduced for the physician a formal monitoring and treatment regimen driven by changes in the vital capacity lung volume. The substance of this plan is presented in this manuscript.

Chest wall motion in neonates utilizing respiratory inductive plethysmography.

After calibration, respiratory inductive plethysmography can accurately measure breathing patterns noninvasively by transmitting ribcage and abdomen compartment changes caused by ventilation through oscillator circuitry. We measured the breathing pattern of nine quietly awake healthy newborn infants and assessed components reflecting asynchrony, paradoxic motion, and overall phasic relations between ribcage and abdomen compartments. Breathing pattern data (mean +/- SD) on 136 total tidal volume (Vt) breaths revealed: Vt, 14.4 +/- 3.40 ml; frequency, 52.1 +/- 11.5 beats/min; ribcage contribution to Vt, 32.2% +/- 13.4%; maximum compartmental amplitude/Vt, 1.01 +/- 0.01; phase angle, 13.2 +/- 9.50 degrees; inspiratory asynchrony index, 0.26 +/- 0.20 ml2/ml; expiratory asynchrony index, 0.42 +/- 0.3 ml2/ml; and average asynchrony index, 0.34 +/- 0.20 ml2/ml. Results demonstrated a high degree of synchrony between ribcage and abdomen movement during quietly awake breathing. Outward motion of the abdomen preceded that of the ribcage for almost every measured breath.

A novel vesicle-associated protein (VAP-1) in sea urchin eggs containing multiple RNA-binding consensus sequences.

We have identified a novel high molecular weight, vesicle-associated protein (VAP-1) in the eggs of the sea urchin Strongylocentrotus purpuratus. Biochemical fractionation and immunofluorescence analysis of unfertilized eggs indicate that VAP-1 is a peripheral membrane protein associated with microsomal membrane fractions. Sequence analysis of partial VAP-1 cDNA clones reveals that the protein contains at least four RNA-binding consensus sequences. The RNA-binding sequences are separated by several glycine rich domains and this organization, RNA-binding domains separated by glycine rich sequences, is common to several RNA-binding proteins including the heterogeneous ribonuclear protein A1 and nucleolin. The characteristics of VAP-1 suggest that the protein may function as a multidomain RNA-binding protein. The possibility that VAP-1 may play a role in nuclear RNA processing is also discussed.

Breathing patterns in lambs after oleic acid lung injury utilizing respiratory inductive plethysmography.

We measured breathing patterns utilizing a respiratory inductive plethysmograph (RIP) in seven healthy nonsedated lambs after an iv infusion of oleic acid (50 mg/kg) to induce acute pulmonary edema. Our single position graphic (SPG) calibration technique was employed for gain factor calculation. Accuracy was validated by the simultaneous volume measurement of RIP and integrated pneumotachography (PNT). Of a total 840 validation breaths, 467 (56%) were within 5% of PNT, 734 (87%) were within 10%, and 834 (99.9%) were within 20%. In each study baseline physiologic and breathing pattern data were collected and also at 15, 30, 60, 90, 150, and 210 min postoleic acid infusion. Validation of RIP accuracy before each data collection revealed 29% required new gain factor calculation. Recalibration was done within 5 min. Excluding respiratory frequency, which remained at 30% above baseline, variables were not significantly different than baseline measurements at the 210-min interval. Results suggest that calibration of RIP using our SPG technique is a time-efficient method and that RIP can accurately measure breathing patterns, providing an additional tool for assessment of experimental lung injury in lambs.

Calibration of respiratory inductive plethysmography during quiet and active sleep in lambs.

Respiratory inductive plethysmography provides a noninvasive method of measuring breathing patterns. Calibration of respiratory inductive plethysmography requires calculation of gain factors for ribcage and abdomen transducers utilizing 2 breathing patterns with different ribcage and abdomen contributions and tidal volume measured by either spirometry or integrated pneumotachography. The purpose of this study was to determine if respiratory inductive plethysmography can be calibrated to provide accurate measurements during quiet and active sleep in lambs. We used a least squares linear regression calibration technique with breaths selected from quiet sleep and active sleep to calculate gain factors in 6 tracheostomized lambs. Validation of gain factors was performed by comparing tidal volumes obtained simultaneously by respiratory inductive plethysmography and pneumotachography during quiet sleep and active sleep. Tidal volume differences between respiratory inductive plethysmography and pneumotachography on validation runs of 15 consecutive breaths each revealed 90% of validation breaths within +/- 20% during quiet sleep and 82% of validation breaths within +/- 20% during active sleep. These data provide evidence that respiratory inductive plethysmography can be calibrated to allow breathing pattern measurement during sleep.

Calibration of the respiratory inductive plethysmograph with the single position graphic technique. Accuracy in different behavior states in lambs.

Respiratory inductive plethysmography (RIP) can measure breathing patterns noninvasively. Calibration is required for rib cage and abdomen transducers utilizing breaths with different compartment contribution correlated with tidal volume measured by integrated pneumotachography (PNT). This study was performed to determine if RIP remains accurate during sleep states following calibration in the quietly awake state. We used our single position graphic calibration technique (SPG) to calculate gain factors in seven tracheostomized lambs. Validation of gain factors was accomplished by comparing tidal volume obtained simultaneously by RIP and PNT during quiet wakefulness (QW), quiet sleep (QS) and active sleep (AS). Results of the study showed that RIP was accurately calibrated during QW. Accuracy was decreased during QS and AS.

Face mask application for calibration of respiratory inductive plethysmography in lambs.

Respiratory inductive plethysmography is a non-invasive method of assessing breathing patterns that requires an airway connection for calibration. In previous studies an endotracheal tube was used to establish this connection. We employed a single position graphic calibration technique for gain calculation using a conical face mask in place of the endotracheal tube, thus eliminating the need for sedation and topical anaesthesia. Thirteen studies were completed on seven lambs. Validation of gains was performed by comparing volumes obtained simultaneously by respiratory inductive plethysmography and integrated pneumotachography. Total study time ranged between 5 and 10 min for each calibration procedure. Our results suggest that the conical mask can be used to perform accurate and time-efficient calibration of the respiratory inductive plethysmograph in the spontaneously breathing non-sedated lamb and eliminates the need for endotracheal intubation.

Calibration of respiratory inductive plethysmography in lambs receiving intermittent mandatory mechanical ventilation.

Respiratory inductive plethysmography (RIP) is a noninvasive method of assessing breathing pattern. We employed a single-position graphic (SPG) calibration technique for gain factor calculation in 38 studies on five sedated lambs who were receiving intermittent mandatory mechanical ventilation (IMV). The SPG technique uses selection of two breaths from a 20-sec run of breaths with different ribcage/pneumotachograph (PNT) and abdomen/PNT ratios for gain calculation. Validation of gains was performed by comparing volumes obtained simultaneously by RIP and PNT. The mean tidal volume (VT) measured by RIP corresponded well with mean VT measured by PNT with animals receiving 42.2 +/- 13.2 (SD) % of breaths over 1 min by IMV. Time for calibration and validation ranged between 15 and 30 min. The results of this study suggest that the SPG calibration technique provides an accurate method of calibration of RIP in sedated lambs receiving IMV.

Calibration of respiratory inductive plethysmography in spontaneously breathing lambs and piglets.

Respiratory inductive plethysmography is a method of assessing breathing pattern without an airway connection. We employ a single position graphic calibration technique for gain factor calculation. Nineteen studies were completed in piglets and 20 studies were completed in lambs. The single position graphic technique utilizes selection of two breaths from a 20 s run of breaths with different ribcage/pneumotachograph and abdomen/pneumotachograph ratios for gain calculation. Validation of gains was performed by comparing volumes obtained simultaneously by respiratory inductive plethysmography and pneumotachography. Total study time ranged between 15 and 30 min. Results suggest that the single position graphic calibration technique provides time-efficient and accurate calibration of respiratory inductive plethysmography in the spontaneously breathing, sedated lamb and piglet, allowing respiratory inductive plethysmography to become an additional tool for ventilatory parameter measurement.

Breathing patterns in infants utilizing respiratory inductive plethysmography.

Respiratory inductive plethysmography (RIP) is a method that can be used to assess breathing patterns in infants without an airway connection. Ribcage and abdomen transducers are used which require gain factor calculation for calibration. We employed a single position graphic (SPG) calibration technique for gain factor calculation in RIP to obtain breathing pattern data for 70 infants in the quietly awake state. The SPG technique utilizes selection of two breaths from a 20s run of breaths with different ribcage/pneumotachograph (RC/PNT) and abdomen/pneumotachograph (AB/PNT) ratios for the gain factor calculation. Validation of gain factors was performed by comparing volumes obtained simultaneously by RIP and PNT. In 46 of the infants, maintenance of gain factor accuracy was confirmed following position reversal. Revalidation after position change could not be accomplished in 24 infants who were aroused into an agitated state. Breathing patterns were collected by RIP alone on the 46 infants who remained accurately calibrated in the supine and prone positions. No significant correlations were found between breathing pattern data and anthropometric characteristics. When the infants were repositioned, no consistent pattern of change could be identified. This study suggests that the SPG technique provides time-efficient and accurate calibration of RIP in the newborn infant. Furthermore, accuracy is maintained through position change if the infant remains in the same behavioral state. Breathing pattern data presented is representative of normative values in the quietly awake state for our study population.

Tropomyosin in peripheral ruffles of cultured rat kidney cells.

Tropomyosin distribution has been studied in two normal lines and one transformed line of rat kidney cells during the early phases of substrate attachment and growth. One non-motile normal line, which spreads rapidly after attachment, immediately begins to assemble prominent stress fibers that contain tropomyosin. It displays small peripheral ruffles that are not noticeably stained with anti-tropomyosin. The other normal line is motile and produces large ruffles that are brightly stained with anti-tropomyosin. Large numbers of tropomyosin-positive stress fibers assemble only after the cells stop moving and lose the peripheral ruffles. The transformed line does not assemble stress fibers but does contain large numbers of actin filament bundles in ruffles on the cell surface that are stained with anti-tropomyosin. These observations indicate that cytoskeletal tropomyosin is not restricted in distribution to stress fibers, and may undergo re-organization along with actin during the transition from motile to non-motile behavior.

Ticarcillin/clavulanic acid pharmacokinetics in children and young adults with cystic fibrosis.

The single-dose pharmacokinetics of ticarcillin and clavulanic acid (Timentin) were evaluated in children and young adults with cystic fibrosis after a 0.5-hour intravenous infusion of both a 3.1 and a 3.2 gm formulation (representing 3.0 gm ticarcillin combined with 100 mg and 200 mg clavulanic acid, respectively) in a crossover design. A 75 mg/kg dose of the ticarcillin component was used. Model-dependent and noncompartmental pharmacokinetic parameters were congruous. The disposition of ticarcillin and clavulanic acid was characterized adequately by a one-compartment open model. The elimination half-life, apparent steady-state volume of distribution, and total body clearance of ticarcillin from serum were 1.19 hours, 0.231 L/kg, and 0.150 L/hr/kg, respectively, for the 3.1 gm formulation and 1.21 hours, 0.211 L/kg, and 0.123 L/hr/kg, respectively, for the 3.2 gm formulation. For ticarcillin, 86% and 93% of the dose of the 3.1 and 3.2 gm formulations, respectively, were excreted unchanged in urine during the first 6 hours after infusion. Concomitant renal clearance values were 0.120 and 0.112 L/hr/kg for the 3.1 and 3.2 gm formulations, respectively. Approximately 50% of a clavulanic acid dose was excreted unchanged in urine during the 6-hour postinfusion period for both formulations. For ticarcillin, no significant differences were observed between the 3.1 and 3.2 gm formulations. For clavulanic acid, a significant difference between the two formulations was observed in comparison of the area under the serum concentration vs time curve and dose size (P less than 0.01). Linear inverse relationships were identified between demographic factors (e.g., age, weight, height, body surface area) and both the apparent volume of distribution and total body clearance of ticarcillin and clavulanic acid for both formulations. The ticarcillin/clavulanic acid combination in either the 3.1 or 3.2 gm formulation is suitable for microbiologic and clinical evaluation in patients with cystic fibrosis.

Calibration of computer-assisted (Respicomp) respiratory inductive plethysmography in newborns.

We investigated the accuracy of a computer-assisted, respiratory inductive plethysmograph (Respicomp) on 50 awake human newborns who were lying supine. Breaths were selected with different rib cage (RC) to pneumotach (PNT) and abdomen (AB) to pneumotach (PNT) values. The equation RC/PNT + AB/PNT = 1 was solved using the least squares method (LSQ) of calculation of calibration factors. Validation of the calibration factors was performed with a range of consecutive breaths between 6 and 22. Of the 1,128 validation or revalidation breaths, 628 (56%) were within 10% of the simultaneously measured PNT volume, 1,024 (91%) were within 20%, and 1,128 (100%) were within 30%. The RC or AB compartment contributions to ventilation changed spontaneously in the awake newborns. This change eliminated the need to wait for varying sleep states to obtain calibration factors and reduced total time required for calibration. (Some loss of accuracy is a compromise with this method; the calibration factors obtained do not remain accurate while the infant is asleep.) This method provided a reliable and rapid calibration and validation technique of the respiratory inductive plethysmograph (Respicomp) on awake newborns.

Axonal microtubules of crayfish and spiny lobster nerve cords are decorated with a heat-stable protein of high molecular weight.

Axons of crayfish and spiny lobster ventral nerve cords contain large numbers of microtubules that are decorated with fine filaments. These microtubules can be stabilized in permeabilized axons using buffers that contain either polyethylene glycol or glycerol/dimethyl sulphoxide. In the former, the stabilized microtubules retain their filaments and their normal spacing; in the latter, the filaments are stripped off and the bare microtubules collapse onto one another. This observation has been used as the basis for a method of identifying some of the proteins that make up the filaments. Axons are first permeabilized and stabilized in either buffer and then treated with a microtubule-depolymerizing buffer. The axons treated first with polyethylene glycol release tubulin and significant quantities of microtubule-associated proteins (MAPs), while the axons pre-treated with glycerol release tubulin and only traces of associated proteins. One of the proteins released in largest quantity along with tubulin from polyethylene glycol-treated axons is a high molecular weight, heat-stable MAP that co-electrophoreses with MAP-2 from mammalian brain. This same protein co-purifies with tubulin that is obtained from crayfish nerve cords by two cycles of polymerization and depolymerization. It is concluded that this protein is a component of the filaments that decorate the axonal microtubules of the crayfish and spiny lobster.

Pediatric aerosol therapy guidelines. Indications, techniques, and dosages.

Delivery of medication in aerosol form to the pediatric population is an important therapeutic module. Aerosol therapy allows rapid medication effects, reduces systemic side effects, and provides uniform results in comparable clinical presentations if preparation techniques and dosages are appropriate. The effectiveness of aerosol therapy is dependent upon several key factors, and techniques developed to emphasize these factors will maximize aerosol delivery into the tracheobronchial tree. Indications for medical aerosol therapy are specific for children, and individualized treatment can be structured for a wide variety of pulmonary disorders. Proper and successful administration of aerosol therapy to the infant or child requires a comprehensive amount of skill and knowledge on the part of the respiratory therapy practitioner. Guidelines discussed in this paper will assist the respiratory care practitioner in achieving optimal results in treating airway disease in the pediatric patient.

Dynamics of keratin filaments and the intermediate filament distribution center during shape change in PtK1 cells.

Reorganization of intermediate filaments during cell spreading is examined by immunofluorescence, electron microscopy, and time-lapse video microscopy. A juxtanuclear cap, believed to correspond to the intermediate filament distribution center, was observed to be spatially related to the organization of the intermediate filament network as cells spread. A keratin cap was observed, which appeared spontaneously in motile PtK1 cells. Cap formation may be a consequence of retraction of intermediate filaments from the cytoplasm as cells move. The position of this juxtanuclear cap is related to the direction of movement, located on the side of the nucleus near the advancing edge of the cell. As the cell spreads, the cap disappears as the keratin filament network returns to the cytoplasm. Evidence presented here is consistent with the hypothesis that the distribution center mediates keratin filament organization during cell shape change.