Tube Feed Necrosis after Major Gastrointestinal Oncologic Surgery: Institutional Lessons and a Review of the Literature.

BACKGROUND: Small bowel necrosis after enteral feeding through a jejunostomy tube (tube feed necrosis, TFN) is a rare, serious complication of major abdominal surgery. However, strategies to reduce the incidence and morbidity of TFN are not well established. Here, in the largest series of TFN presented to date, we report our institutional experience and a comprehensive review of the literature. METHODS: Eight patients who experienced TFN from 2000 to 2014 after major abdominal surgery for oncologic indications at the University of Cincinnati were reviewed. Characteristics of post-operative courses and outcomes were reviewed prior to and after a change in tube-feeding protocol. The existing literature addressing TFN over the last three decades was also reviewed. RESULTS: Patients with TFN ranged from 50 to 74 years old and presented with upper gastrointestinal tract malignancies amenable to surgical resection. Six and two cases of TFN occurred following pancreatectomy and esophagectomy, respectively. Prior to TF protocol changes, which included initiation at a low rate, titrating up more slowly and starting at one-half strength TF, three of six cases of TFN (50%) resulted in mortality. With the new TF protocol, there were no deaths, goal TF rate was achieved 3 days later, symptoms of TFN were recognized 3 days earlier, and re-operation was conducted 1 day earlier. CONCLUSION: This case series describes a change in clinical practice that is associated with decreased morbidity and mortality of TFN. Wider implementation and further refinement of this tube-feeding protocol may reduce TFN incidence at other institutions and in patients with other conditions requiring enteral nutrition.

Adding sildenafil vaginal gel to clomiphene citrate in infertile women with prior clomiphene citrate failure due to thin endometrium: a prospective self-controlled clinical trial.

We aimed to investigate the effect of adding sildenafil vaginal gel to clomiphene citrate (CC) in infertile women with prior CC failure. METHODS: This is a self- controlled clinical trial. Women with CC failure (in prior 5 cycles) and thin endometrium were recruited (N = 42). In their 6th (CC only) cycle, women continued on CC 100 mg/ day for 5 days, and had measurement of endometrial thickness and Doppler assessment of uterine arteries on day of HCG administration. In the 7th cycle, women (N = 36) were given usual dose of CC supplemented with sildenafil vaginal gel (5 gm, containing 50 mg sildenafil) twice daily from cycle day 8 to day of HCG administration. Endometrial thickness and uterine artery Doppler were measured on the day of HCG injection. RESULTS: In the 7th (CC + sildenafil vaginal gel) cycle, endometrial thickness was significantly higher than in the 6th (CC only) cycle (9.3 mm +/- 3.1mm versus 6.6 mm +/- 1.4 mm, respectively, P = < 0.001). Uterine artery pulsatility index dropped from 2.4 +/- 0.8 in 6th cycle to 1.6 +/- 1.3 in 7th cycle (P = 0.002). Clinical pregnancy rate increased but numbers were too small (only 3 pregnancies). CONCLUSION: Sildenafil vaginal gel significantly increased endometrial thickness and uterine blood flow, and may improve pregnancy rate in patients with CC failure due to thin endometrium. Mucoadhesive vaginal gel formulation allowed shorter duration of sildenafil application, and less frequent daily dosing.

Surprising similarity between mechanisms mediating low (1 Hz)-and high (100 Hz)-induced long-lasting synaptic potentiation in CA1 of the intact hippocampus.

It is generally assumed that long lasting synaptic potentiation (long-term potentiation, LTP) and depression (long-term depression, LTD) result from distinct patterns of afferent activity, with high and low frequency activity favouring LTP and LTD, respectively. However, a novel form of N-methyl-d-aspartate (NMDA) receptor-dependent synaptic potentiation in the hippocampal CA1 area in vivo induced by low frequency afferent stimulation has recently been demonstrated. Here, we further characterize the mechanisms mediating this low frequency stimulation (LFS)-induced LTP in area CA1 of intact, urethane-anesthetized preparations. Consistent with previous reports, alternating, low frequency (1 Hz) stimulation of CA1 afferents originating in the contralateral CA3 area and the medial septum resulted in gradually developing, long lasting (>2 h) LTP of field excitatory postsynaptic potentials (fEPSPs) recorded in CA1. Local application of the protein synthesis inhibitor anisomycin in CA1 blocked LFS-induced LTP, as did application of H89, an inhibitor of protein kinase A. Given the apparent overlap in molecular mechanisms mediating LFS-LTP and "classic" high-frequency stimulation (HFS)-induced LTP in CA1, we examined the relation between these forms of LTP by means of occlusion experiments. LFS, delivered to synapses saturated by initial HFS, resulted in a gradually developing LTD, rather than the normally seen LTP. Conversely, initial induction of LFS-LTP reduced the amount of subsequent HFS-LTP. Together, these experiments reveal a surprising similarity in the molecular mechanisms (dependence on NMDA receptors, protein kinase A, protein synthesis) mediating LTP induced by highly distinct (1 vs. 100 Hz) induction protocols. Importantly, these findings further challenge the "high-frequency-LTP, low-frequency LTD" dogma by demonstrating that this dichotomy does not account for all types of plasticity phenomena at central synapses.

Effectiveness of cognitive behaviour therapy in schoolchildren with depressive symptoms in Alexandria, Egypt.

We evaluated the effectiveness of cognitive behaviour therapy for 12-14-year-old school-children from a low socioeconomic area in Alexandria, Egypt during the academic year 2003-04. Our sample comprised 198 boys and 136 girls. Students were assessed using the Child Depression Inventory and the Coopersmith Self-Esteem Inventory. The frequency of depression was 9.6%; 7.1% in boys and 13.2% in girls. The 32 children with depression were offered cognitive behaviour therapy. Only 17 accepted the offer and received 9 sessions of therapy. They were assessed 3 months after the intervention using the same tools and the results indicate the short-term effectiveness of the therapy.

Second-trimester pregnancy termination: comparison of three different methods.

The object of this study was to compare intravaginal misoprostol and dinoprostone (prostaglandin E2) for second-trimester pregnancy termination, and to examine the role of the nitric oxide donor, glyceryl trinitrate, as a possible alternative to prostaglandins to induce cervical ripening in second-trimester pregnancy termination. This was a randomised clinical trial. The trial involved pregnant women between 13 and 28 weeks' gestation admitted with clear medical or obstetric indications for pregnancy termination, and was carried out in the department of obstetrics and gynecology, Assiut University Hospital, Egypt. Patients were classified into Group A, where pregnancy termination was induced by vaginal misoprostol 100 micrograms every 4 hours with a maximum dose of 500 micrograms; Group B, where induction was by vaginal dinoprostone 6 mg every 6 hours with a maximum dose of 24 mg; and Group C, where induction involved vaginal glyceryl trinitrate 500 micrograms every 6 hours with a maximum dose of 2.5 mg. Twenty-four hours after the start of induction, the rate of complete abortion in the three groups was 100%, 66.67% and 0%, respectively. The rate of complete abortion was 100% in the nitric oxide (glyceryl trinitrate)-induced group after introducing a complementary procedure. The induction-abortion interval was significantly shorter, the number of doses needed was less and the maximum Bishop score reached was greater with misoprostol than with dinoprostone. A higher rate of side effects occurred with the misoprostol-induced group (74%) compared with the other two groups (46.6% and 0%). Misoprostol is a cheap, effective drug for second-trimester pregnancy termination with short induction abortion intervals but a higher rate of side effects. Prostin E2 is also effective in termination of second-trimester pregnancy but is expensive and may require high doses to be administered. Glyceryl trinitrate is an effective drug for cervical ripening (softening) but it has no role in the stimulation of uterine contractions.

Large interarcuate spaces in the cervical vertebral column of the tyrolean mountain sheep.

Large interarcual spaces have been described between the arcus vertebrae C5/C6 and C6/C7 in the cervical vertebral column of Nubian goats. This aperture enables direct access to spinal cord and rootlets without the need to perform a hemilaminectomy. The present study was performed in order to determine whether these large interarcual spaces can also be found in the vertebral column of the Tyrolean mountain sheep, as this small ruminant, which is anatomically very similar to the Nubian goat, is frequently used for experimental purposes at the Surgical University Clinic in Austria. The carcasses of 10 sheep (six females, four males; range of age: 2.5-6 years, range of weight: 52-89 kg) were dissected and the vertebral column was exposed. All 10 sheep showed elliptic openings between the fourth cervical and the first thoracal vertebrae. Three sheep had additional openings between the first and the second thoracal vertebrae. All openings were covered solitarily by the ligamentum flavum and under this ligamentum lay the spinal cord without any further osseous or ligamentous protection. These findings are not mentioned in the common textbooks of veterinary anatomy and deserve attention, as they can be a step forward towards non-traumatic experimental surgery on the spinal cord.

Two administration methods for inhaled salbutamol in intubated patients.

AIMS: To compare serum concentrations and effects on respiratory mechanics and haemodynamics of salbutamol administered by small volume nebuliser (SVN) and metered dose inhaler (MDI) plus spacer. METHODS: Blinded, randomised, crossover study in 12 intubated infants and children (mean age 17.8 months) receiving inhaled salbutamol therapy. Subjects received salbutamol as 0.15 mg/kg by SVN and four puffs (400 microg) by MDI plus spacer at a four hour interval in random order. Passive respiratory mechanics were measured by a single breath/single occlusion technique, and serum salbutamol concentrations by liquid chromatography-mass spectrometry at 30 minutes, 1, 2, and 4 hours after each dose. Haemodynamics (heart rate and blood pressure) were recorded at each measurement time. RESULTS: There was no difference in percentage change in respiratory mechanics or haemodynamics between the two methods of administration. Mean area under the curve (AUC(0-4)) was 5.86 for MDI plus spacer versus 4.93 ng/ml x h for SVN. CONCLUSIONS: Serum concentrations and effects on respiratory mechanics and haemodynamics of salbutamol were comparable with the two administration methods under the conditions studied. Future studies are needed to determine the most effective and safe combination of dose and administration method of inhaled salbutamol in mechanically ventilated infants and children.

Identification of a high affinity nucleocapsid protein binding element within the Moloney murine leukemia virus Psi-RNA packaging signal: implications for genome recognition.

Murine leukemia virus (MLV) is currently the most widely used gene delivery system in gene therapy trials. The simple retrovirus packages two copies of its RNA genome by a mechanism that involves interactions between the nucleocapsid (NC) domain of a virally-encoded Gag polyprotein and a segment of the RNA genome located just upstream of the Gag initiation codon, known as the Psi-site. Previous studies indicated that the MLV Psi-site contains three stem loops (SLB-SLD), and that stem loops SLC and SLD play prominent roles in packaging. We have developed a method for the preparation and purification of large quantities of recombinant Moloney MLV NC protein, and have studied its interactions with a series of oligoribonucleotides that contain one or more of the Psi-RNA stem loops. At RNA concentrations above approximately 0.3 mM, isolated stem loop SLB forms a duplex and stem loops SL-C and SL-D form kissing complexes, as expected from previous studies. However, neither the monomeric nor the dimeric forms of these isolated stem loops binds NC with significant affinity. Longer constructs containing two stem loops (SL-BC and SL-CD) also exhibit low affinities for NC. However, NC binds with high affinity and stoichiometrically to both the monomeric and dimeric forms of an RNA construct that contains all three stem loops (SL-BCD; K(d)=132(+/-55) nM). Titration of SL-BCD with NC also shifts monomer-dimer equilibrium toward the dimer. Mutagenesis experiments demonstrate that the conserved GACG tetraloops of stem loops C and D do not influence the monomer-dimer equilibrium of SL-BCD, that the tetraloop of stem loop B does not participate directly in NC binding, and that the tetraloops of stem loops C and D probably also do not bind to NC. These surprising results differ considerably from those observed for HIV-1, where NC binds to individual stem loops with high affinity via interactions with exposed residues of the tetraloops. The present results indicate that MLV NC binds to a pocket or surface that only exists in the presence of all three stem loops.

Biological characterization and chemokine receptor usage of HIV type 1 isolates prevalent in Brazil.

The human immunodeficiency virus type 1 (HIV-1), the etiological agent of the acquired immunodeficiency syndrome (AIDS), shows a variety of biological properties, which may constitute an obstacle to development of effective vaccines or antiretroviral therapy. To characterize Brazilian strains of HIV-1, we studied 24 viruses isolated from blood samples of HIV-1-positive patients from different regions of the country. To examine the cell tropism and the virus ability to form syncytia, primary macrophages and the CD4+ T cell line MT-2 were infected with these viruses. We found that 22 isolates replicated well in macrophages (macrophage-tropic isolates), 2 infected only MT-2 cells (T cell line tropic variants), while 6 of them grew in both cells. We found 8 syncytium-inducing (SI) and 16 non-SI (NSI) isolates. Continuous cultures of 18 isolates were established in the CCR5+/CXCR4+ cell line PM-1, and SI/NSI features of these viruses were confirmed by cell fusion assay with uninfected CD4+ T cell lines (PM-1, MT-2, H9, and SUP-T1). The coreceptor usage of 18 isolates was investigated by infecting U87 cells transfected with CD4 and chemokine receptors, and we found that 11 isolates infected only CCR5+ cells, 3 only CXCR4+ cells, whereas 4 used both coreceptors. We also observed that X4 isolates were more sensitive to neutralization by dextran sulfate than R5 or R5X4 viruses. Our findings show that the Brazilian isolates are phenotypically similar to those prevalent in other regions, which could mean that therapeutic strategies based on HIV-1 phenotypic properties would be efficient in Brazil, as in other countries.

Antileishmanial activity of an indole alkaloid from Peschiera australis.

In this study, we show the leishmanicidal effects of a chloroform fraction (CLF) and a purified indole alkaloid obtained from crude stem extract of Peschiera australis against Leishmania amazonensis, a causative agent of cutaneous leishmaniasis in the New World. In a bioassay-guided chemical fractionation, the leishmanicidal activity in CLF completely and irreversibly inhibited promastigote growth. This fraction was also active against amastigotes in infected murine macrophages. Chemical analysis of CLF identified an iboga-type indole alkaloid coronaridine as one of its major compounds. Coronaridine showed potent antileishmanial activity, inhibiting promastigote and amastigote growth. Promastigotes and amastigotes treated with CLF or coronaridine showed pronounced alterations in their mitochondria as assessed by transmission electron microscopy.

Routine chest radiographs in pediatric intensive care units.

OBJECTIVES: To determine whether interventions were performed based on portable routine morning chest x-rays (CXRs) in pediatric intensive care unit (PICU) patients and to identify patient subgroups for whom the routine CXR is most useful. DESIGN: Prospective multiinstitutional study. Setting. PICUs of 15 tertiary care hospitals. Patients. PICU patients who received a routine morning CXR were included in the study. OUTCOME MEASURES: Recorded data included: weight, diagnosis, presence of active cardiopulmonary problems, length of stay, and number and type of devices. The number and types of interventions based on the interpretation of the CXR were recorded. RESULTS: Five hundred twelve routine CXRs were evaluated. The majority of the routine chest radiographs were obtained on patients who were admitted for cardiovascular disease (195/512; 38%) or respiratory failure (186/512; 36%), and 465/512 of the routine CXRs (91%) were performed on patients with one or more devices. Two hundred thirty-one of the 512 routine CXRs (45%) resulted in 1 or more interventions. One hundred fifty-five of the 284 routine CXRs (55%) obtained in children /=40 kg, respectively. The frequency of interventions increased from 19% in children with no devices to >50% in children with 2 or more devices. One or more interventions were performed in 27% of routine CXRs when no active cardiopulmonary problems were present, compared with 51% of routine CXRs when active cardiopulmonary problems were present. Diagnosis and length of intensive care unit stay at the time the routine CXR was obtained did not affect the percentage of CXRs that resulted in interventions. CONCLUSIONS: Routine CXRs are more likely to result in interventions in the smaller, critically ill child with one or more devices and if active cardiopulmonary problems are present.

Effects of a weaning protocol on ventilated pediatric intensive care unit (PICU) patients.

As part of a learning collaborative sponsored by the Center for the Evaluative Clinical Sciences (CECS) at Dartmouth College, a multidisciplinary pediatric intensive care unit (PICU) group began meeting in 1997 to evaluate potential performance improvement (PI) opportunities. A reduction in mechanical ventilation (MV) hours was the initial team focus. The multidisciplinary team developed and implemented protocols and physician order sets outlining care for MV weaning, neuromuscular blockade/therapeutic paralyzation, and enteral feedings. Since the initiation of our protocols in July 1997, we have significantly reduced the number of hours our PICU patients receive MV.

Elevated serum and bronchoalveolar lavage fluid levels of interleukin 8 and granulocyte colony-stimulating factor associated with the acute chest syndrome in patients with sickle cell disease.

The role of cytokines in the development of acute chest syndrome (ACS) in patients with sickle cell disease (SCD) was studied. Serum interleukin 8 (IL-8) levels were elevated in 14 episodes and undetectable in six out of 20 episodes of ACS in 19 patients with SCD. In contrast, IL-8 levels were undetectable in the sera of 29 control patients with SCD studied during routine clinic visits or hospitalization for vaso-occlusive crises. The differences in mean IL-8 levels and the proportion of patients with detectable levels between the two groups were highly significant (P < 0.0001 and 0.04 respectively). The mean IL-8 level in bronchial fluid samples from children with ACS was also significantly higher than that in sickle cell patients undergoing elective surgery (5500 +/- 1400 pg/ml vs. 1900 +/- 470 pg/ml, P = 0.03). Granulocyte colony-stimulating factor (G-CSF) (2000 +/- 1700 pg/ml) was present in five out of six samples of bronchial fluid, but not serum, from children with ACS. All but one of the patients with ACS studied were negative for the Duffy red cell antigen, which is a receptor that binds and inactivates IL-8 and other chemokines. These findings suggest that IL-8 and G-CSF may play a role in the development of the ACS and the complications associated with it.

HIV-1 diversity in Brazil: genetic, biologic, and immunologic characterization of HIV-1 strains in three potential HIV vaccine evaluation sites. Brazilian Network for HIV Isolation and Characterization.

The Brazilian Network for HIV Isolation and Characterization was established for the surveillance of HIV variability in Brazil. Here, we report characterization of HIV strains and virus-specific immune responses from 35 clinical samples collected from three potential HIV vaccine sites. Three genetic subtypes of HIV-1 were identified by heteroduplex mobility assay (HMA) B (in 82.9% of the samples), F (14.3%), and C (2.9%). Phylogenetic analysis based on the C2V3/env DNA sequence from all 25 specimens examined was 100% concordant with HMA results. Four variants of subtype B with different tetrapeptides at the tip of the V3 loop were found: the GPGR motif (North American), GWGR motif (Brazilian B"), and two minor variants, GFGR and GPGS, as previously detected. No significant association was found between HIV-1 subtypes and the mode of transmission or biologic properties of HIV-1 isolates (derived from 88.6% of the specimens). Only 5 of 16 isolates studied were neutralized by the autologous sera. Consistent with previous results, no relation between viral subtype and peptide enzyme-linked immunosorbent assay (ELISA) seroreactivity or neutralization was evident. This study also demonstrated the effectiveness of the collaborative approach followed by Brazilian scientists when addressing a complex subject such as HIV variability.

Emergency cardiopulmonary bypass for cardiac arrest refractory to pediatric advanced life support.

We report the application of emergent cardiopulmonary bypass (CPB) for three pediatric patients in the cardiac catheterization laboratory with cardiac arrest who did not respond to conventional resuscitation efforts. All three patients had return of baseline prearrest rhythms within minutes of the initiation of artificial cardiopulmonary support and the return of spontaneous circulation upon weaning CPB. Two patients had normal neurologic outcomes despite an interval of over 30 minutes from arrest to CPB. The continued judicious application and study of this technology in a small subpopulation of pediatric cardiac arrest patients is warranted.

Effect of helium-oxygen on delivery of albuterol in a pediatric, volume-cycled, ventilated lung model.

Pulmonary delivery of inhaled bronchodilators in mechanically ventilated patients is inefficient whether administered by metered-dose inhaler (MDI) or small-volume nebulizer. One of the factors that causes inefficient aerosol delivery is turbulent gas. Heliox (He:O2) is a blend of helium and oxygen that is less dense than air, making turbulent flow less likely. We assessed the effect of 70% He:O2 on albuterol delivery in a mechanically ventilated pediatric lung model. Albuterol was administered by MDI with spacer, collected on a filter proximal to a test lung, and measured by high-performance liquid chromatography. Mean amount and percentage albuterol delivered were significantly (p<0.05) greater for 70% He:O2 (395+/-29 microg, 20+/-3.2%) than for 70% nitrogen:30% oxygen (241+/-29 microg,12+/-1.7%). Thus 70% He:O2 can increase the amount of albuterol delivered at the end of the endotracheal tube, suggesting a potential role for it in the care of critically ill ventilated patients.

Pediatric ECMO for severe quinidine cardiotoxicity.

We report the use of extracorporeal membrane oxygenation (ECMO) to establish and maintain cardiovascular stability in a 16 month old with refractory bradydysrrhythmias and hypotension after an acute overdose of quinidine. He underwent an 11-day course of ECMO and was discharged with normal neurologic function. This case illustrates the role ECMO can play in the treatment of profound cardiovascular collapse caused by toxic ingestions. To be optimally effective, management of such patients must be anticipatory.

Prediction of childhood drowning and near-drowning morbidity and mortality.

OBJECTIVES: (a) Evaluate the presenting hemodynamic status and neurologic function of a series of warm water submersion injuries. (b) To ascertain the importance of the timing of the neurologic examination. (c) To identify risk factors that predict which patients will not return to presubmersion status. DESIGN: Retrospective review of all patients with a diagnosis of drowning/near-drowning responded to by the Children's Hospital pediatric transport service. Data were collected over a 24-month period regarding patient characteristics, submersion medium, rescue efforts, time out of sight, elapsed times to emergency department (ED) and pediatric intensive care unit (PICU) arrival, neurologic and hemodynamic status on arrival at the ED and PICU, reconstructed Conn-Modell category, and neurologic outcome. SETTING: EDs of the referring hospitals and PICU of the Children's Hospital of Orange County (CHOC), California. PATIENTS: Ninety-three submersion victims at an average age of 31 months. All patients were provided intensive care support. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Twenty-three percent (21/ 93) of patients died or survived vegetative. No patient arriving comatose and asystolic in the ED survived neurologically intact (n = 21, three patients expired in the ED). This group of patients had a mean duration of documented asystole = 41 minutes, range of 18 to 107 minutes, and time to ED arrival = 21 minutes. All patients with a detectable pulse and blood pressure (n = 72) on arrival to the ED, regardless of their neurologic status, recovered to their presubmersion status. Patients arriving comatose (decorticate, decerebrate, or flaccid posture) in the PICU (n = 18, mean arrival = 192 minutes) all died or were vegetative. All patients with non-coma (n = 72, Conn-Modell category A or B) on arrival to the PICU recovered normally. CONCLUSIONS: Hemodynamic status in the ED and neurologic status in the PICU are highly predictive of outcome. On arrival to the ED, the cardiovascular status is more predictive of abnormal outcome than neurologic status. Poor neurologic outcome appears inevitable for warm water submersion victims who are asystolic at ED arrival and remain comatose for more than 200 minutes.

Albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model.

OBJECTIVES: To assess albuterol delivery by metered-dose inhaler in a mechanically ventilated pediatric lung model and to determine the influence of the following variables on albuterol delivery: endotracheal tube diameter; type of spacer; humidification; and pulmonary mechanics. DESIGN: Prospective, in vitro, laboratory study. SETTING: Research laboratory. INTERVENTIONS: A model, consisting of a volume-cycled ventilator, pediatric breathing circuit, 4.0- or 6.0-mm endotracheal tube, and lung simulator, was assembled. Ventilator settings were: tidal volume 250 mL; FIO2 0.5; inspiration/expiration ratio 1:3; respiratory rate 25 breaths/min; positive end-expiratory pressure 3 cm H2O; temperature 35 degrees C; and a decelerating flow pattern, using dry and humidified air. Lung simulator compliance and resistance values were consistent with those values reported for healthy childeren (20 mL/cm H2O and 40 cm H20/L/sec) and children with pulmonary disease (10 mL/cm H2O and 60 cm H2O/L/sec). Pulmonary mechanics were verified with a pulmonary function diagnostic system. Ten metered-dose inhaler canisters were used to administer 2000 micrograms of albuterol, using either a collapsible or a rigid spacer. A circuit filter placed immediately proximal to the test lung collected drug exiting the endotracheal tube. The filter was rinsed with water and albuterol concentrations were determined by high-performance liquid chromatography. Each variable was tested in triplicate. MEASUREMENTS AND MAIN RESULTS: Albuterol delivery was significantly (p < or = .05) greater for the 6.0-mm endotracheal tube, rigid spacer, dry air, and pulmonary disease mechanics by multifactor analysis of variance. Drug delivery in humidified air with pulmonary disease mechanics using the rigid chamber was 2.5 =/- 0.27% and 6.3 =/- 0.99% for the 4.0- and 6.0-mm endotracheal tubes, respectively. CONCLUSIONS: These in vitro results suggest that pulmonary disease mechanics and a 6.0-mm endotracheal tube improve albuterol delivery. Future clinical investigations in intubated pediatric patients with pulmonary disease are needed to address the clinical significance of these results.

CD26 expression correlates with entry, replication and cytopathicity of monocytotropic HIV-1 strains in a T-cell line.

Experiments to identify cell determinants involved in HIV-1 tropism revealed a specific decrease in the expression of the T-cell activation antigen CD26 after monocytotropic (M-tropic) but not T-cell line-tropic (T-tropic) virus infection of the PM1 T-cell line. The level of CD26 expression in single-cell clones of PM1 correlated with the entry rate and cytopathicity of M-tropic HIV-1 variants, resulting in preferential survival of cells with low CD26 levels after infection. Experiments with recombinant viruses showed that the third hypervariable region of the envelope gp120 plays an important role in this selection process. This study identifies CD26 as a key marker for M-tropic human immunodeficiency virus type 1 (HIV-1) infection and suggests a mechanism for the early loss of CD26-expressing cells in HIV-1-infected individuals.