Respiratory response and ventilatory muscle recruitment during arm elevation in normal subjects.

Despite the fact that the arms are used extensively in daily life and that some of the muscles of the shoulder girdle share both a respiratory and a positional function for the arms, surprisingly little is known about the respiratory response to unsupported upper extremity activity. To determine the respiratory consequences of simple arm elevation during tidal breathing, we measured minute ventilation (VE), tidal volume (VT), respiratory rate (f), heart rate (HR), oxygen uptake (VO2), and carbon dioxide production (VCO2) in 22 normal subjects seated with arms elevated in front of them to shoulder level (AE) for 2 min and down at the sides (AD) for the same time period. The sequence was randomized. Compared with AD, during AE there were significant increases in VO2 (336 +/- 18 vs 289 +/- 14 ml/min, p less than 0.001), VCO2 (315 +/- 23 vs 245 +/- 16 ml/min, p less than 0.001), HR (84 +/- 6 vs 73 +/- 4 beats/min, p less than 0.05), VE (11.5 +/- 0.9 vs 9.3 +/- 0.6 L/min, p less than 0.001), and VT (868 +/- 66 vs 721 +/- 48 ml, p less than 0.001). In 11 subjects, breath-by-breath metabolic and ventilatory parameters were studied with AD for 2 min, AE for 2 min, and with AD for 3 min while also recording gastric (Pg), pleural (Ppl), and transdiaphragmatic pressures (Pdi). With AE, there was a significant increase in Pg at end inspiration (PgI, 15.4 +/- 3.2 vs 11.9 +/- 2.7 cm H2O, p less than 0.01) and in Pdi (26.5 +/- 3.4 vs 21.4 +/- 2.4 cm H2O, p less than 0.01) with no change in Pg at end expiration (PgE) or in Ppl. The increases in VO2, VCO2, VE, and VT during arm elevation persisted for 2 min after arm lowering, whereas Pgi and Pdi abruptly dropped as the arms were lowered. We conclude that simple arm elevation during tidal breathing results in significant increases in metabolic and ventilatory requirements. These increased demands are associated with higher PgI and Pdi suggesting an increased diaphragmatic contribution to the generation of ventilatory pressures. The sudden drop in Pg with arm lowering indicate a change in ventilatory muscle and or torso recruitment independent of the metabolic drive and ventilatory needs. These findings may help explain the limitation that has been reported in some normal subjects and in many patients with lung disease during unsupported upper extremity activity.     

Factors influencing ventilatory muscle recruitment in patients with chronic airflow obstruction

Patients with chronic airflow obstruction (CAO) frequently develop abnormal thoraco-abdominal excursion, but the patterns described are inconsistent and the factors that relate to their development remain unknown. We studied 45 stable patients with FEV1 ranging from 0.36 to 2.1 L. A pattern of ventilatory muscle recruitment (VMR) was established by simultaneously measuring gastric (Pg) and pleural (Ppl) pressures and rib cage (Vrc) and abdominal (Vab) volume displacement with inductance plethysmography. From these tracings, Pg-Ppl plots were constructed and the delta Pg/delta Ppl values were calculated. The delta Pg/delta Ppl was validated in 15 patients with simultaneous analysis of Vab-Pg plots. Pearson's test and multiple regression analyses were used to correlate delta Pg/delta Ppl to factors thought to influence respiratory muscle function such as age, sex, nutritional status (weight/height, albumin), hyperinflation, airflow obstruction, and arterial blood gases. We found a direct correlation between a more positive delta Pg/delta Ppl value and increasing hyperinflation (r = 0.69, p less than 0.0001), increasing airflow obstruction (r = -0.55, p less than 0.001), and decreasing diaphragmatic strength (r2 = 0.32, p less than 0.001). We also found that expiratory Ppl became more positive with decreasing FEV1 (r2 = 0.33, p less than 0.001). This change in VMR was independent of age, sex, nutritional status, and arterial blood gas determinations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Expanding community health nursing roles to meet health-care needs of frail elderly. An adult learning model

The increased training needs for community health nurses (CHNs) working with frail elderly offer a variety of challenges in staff development. Santa Clara County addressed these challenges with an innovative model, and geriatric assessment skills building program presented to 40 CHNs. The model uses a team teaching approach, a preceptorship and adult learning theory, making it readily adaptable to a variety of community health settings.     

Spondylometaphyseal dysplasia, corner fracture type: a heritable condition associated with coxa vara

The authors present the radiographic features of a previously incompletely delineated bone dysplasia, which they call spondylometaphyseal dysplasia, corner fracture type. This is a dominant heritable condition associated with short stature and developmental coxa vara. The progressive hip deformity usually causes significant disability requiring surgical correction. Developmental coxa vara, simulated corner fractures of long tubular bones, and vertebral body abnormalities result in a diagnostic constellation. Knowledge of these distinctive radiologic features allows accurate diagnosis, which in turn should lead to appropriate genetic counseling and possibly to earlier, more efficacious surgical treatment of the coxa vara.     

Side effects and long-term follow-up of corticosteroid therapy in very low birthweight infants with bronchopulmonary dysplasia

Seventy-seven very low birthweight (VLBW) infants (mean birthweight 891 +/- 209 g) with a diagnosis of bronchopulmonary dysplasia (BPD) were treated with a steroid (dexamethasone) in an attempt to wean them from mechanical ventilation. Seventeen of 77 (22%) treated infants died. Death from respiratory failure occurred in 13 infants; sepsis occurred in six infants (7.8%) and contributed to death in one. During steroid therapy systemic hypertension occurred in 18 surviving infants (30%), glucose intolerance occurred in 29 infants (38%), and marked irritability occurred in three infants (3.8%). Elevated blood pressure returned to normal and glucose intolerance resolved in all infants following discontinuation of therapy. Fifty infants were available for follow-up at a mean corrected age of 14.9 +/- 9.8 months. Twenty-two percent required rehospitalization in the first year of life for respiratory illnesses. Results of testing by Bayley Scales of Infant Development were normal in 60% of infants. Fifty percent were considered normal based on both developmental testing and physical examination. Twenty-eight percent had mild to moderate abnormalities, and 22% were severely handicapped. These follow-up results are statistically similar to those recorded in LBW infants with BPD not treated with steroids who were hospitalized during the same period. We conclude that the side effects of steroid therapy for BPD consist primarily of blood pressure elevation, glucose intolerance, and irritability. Causes of death are unchanged by steroids. The incidence of severe infection and the long-term neurologic outcome of high-risk infants with BPD are not appreciably compromised by this therapy. These data suggest that concern for steroid side effects should not prevent additional prospective investigation to determine the role of steroid therapy in the overall management of BPD.     

Complement (C5b-9) induces glomerular epithelial cell DNA synthesis but not proliferation in vitro.

BACKGROUND: The C5b-9 membrane attack complex of complement is the principal mediator of injury induced experimentally by antibodies directed at glomerular cell membranes. In experimental membranous nephropathy, C5b-9 induced injury to the glomerular visceral epithelial cell (VEC) is associated with DNA synthesis, but not cytokinesis. In the current study we determined if C5b-9 increases DNA synthesis in VEC in vitro, and defined the mechanisms involved. METHODS: Rat VEC in vitro were divided into three groups: (1) sensitized with anti-VEC antibody and exposed to sublytic concentrations of C +/PVG serum (normal complement components); (2) anti-VEC antibody and control C-/PVG serum (C6 deficient); (3) no anti-VEC antibody. DNA synthesis (BrdU staining), mitosis (mitotic figures) and cytokinesis (cell counts) were measured at 24 and 48 hours. To examine the expression of specific S-phase and M-phase cell cycle regulatory proteins and their inhibitors, immunostaining and Western blot analysis was performed for cyclin A, CDK2, p21 and p27, cyclin B and cdc2. RESULTS: In the absence of growth factors, sublytic C5b-9 attack did not increase proliferation. In contrast, sublytic C5b-9 attack (group 1) augmented growth factor induced DNA synthesis by 50% compared to controls (groups 2 and 3; P < 0.001), and was accompanied by increased levels of cyclin A and CDK2, and a decrease in the cyclin kinase inhibitor p27 (but not p21). Sublytic C5b-9 attack reduced the expression of the M phase cell cycle proteins, cyclin B and cdc2, accompanied by reduced mitosis (mitotic figures) and cytokinesis (cell number). CONCLUSIONS: Our results show that the C5b-9 augmented growth factor entry into the S phase in VEC is regulated by changes in specific cell cycle regulatory proteins. However, antibody and complement decreased the M phase cell cycle proteins, and prevented VEC mitosis and cytokinesis, suggesting a delay or arrest at the G2/M phase.     

A comparison of polymerase chain reaction and an infectivity assay for human immunodeficiency virus type 1 titration during virus inactivation of blood components

Three examples of human plasma-derived concentrates, intermediate- purity factors VIII and IX, and fibrinogen were spiked with tissue culture-grown human immunodeficiency virus type 1 (HIV-1) strain RF. All examples were freeze-dried and heated at 80 degrees C for 72 hours by using validated production process models. HIV-1 infectivity was measured by a syncytial infectivity assay in C8166 cells and then compared with levels determined by nested HIV polymerase chain reaction (PCR). The infectivity assay demonstrated a reduction index of at least 4.5 log10, while PCR showed an average 1.7 log10. Large amounts of HIV- 1 RNA (10(5)) were still detectable by PCR in samples in which infectivity assays failed to detect any HIV-1. These data suggest that HIV-1 PCR levels do not parallel HIV-1 infectivity levels during virus- inactivation procedures involved in coagulation factor concentrate production. PCR was able to detect the RNA associated with inactivated HIV-1 particles in the factor concentrates, which allows the conclusion that PCR is not a useful test with which to monitor virus-inactivation procedures such as heating at 80 degrees C for 72 hours. This judgment contrasts with the more definite and sensitive role of PCR in diagnosing HIV-1 infection in patients in whom a positive HIV-1 PCR result correlates with active HIV-1 infection and with PCR's usefulness in monitoring virus removal.