RESUMEN
Outbreaks of acute respiratory disease caused by adenovirus are rarely documented in civilian populations, and adenovirus 35 is an uncommon serotype best recognized as a cause of serious disease in immunocompromised patients. An outbreak of adenovirus 35 pneumonia among residents and staff of a chronic care psychiatric facility was investigated. Fourteen (26%) of 53 residents and 4 (2%) of approximately 200 staff had radiographically confirmed pneumonia. Thirteen (93%) of 14 residents with pneumonia were hospitalized, 5 (36%) required mechanical ventilation, and 1 (7%) died. One staff member was hospitalized. Adenovirus infection was diagnosed in 17 (94%) persons with pneumonia by culture or serology and was confirmed as adenovirus 35 infection in 8 persons. Residents with pneumonia had resided at the facility longer than other residents. Chronic illness was not a risk factor for severe disease. Crowding and poor hygienic behaviors probably facilitated transmission among residents.
Asunto(s)
Infecciones por Adenoviridae/epidemiología , Infección Hospitalaria/epidemiología , Brotes de Enfermedades , Hospitales Psiquiátricos , Personal de Hospital , Neumonía Viral/epidemiología , Infecciones por Adenoviridae/virología , Adenovirus Humanos/clasificación , Adulto , Infección Hospitalaria/virología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Serotipificación , Células Tumorales CultivadasRESUMEN
OBJECTIVE: To investigate differences between hospitals in clinical management of patients admitted with fractured hip and to relate these to mortality at 90 days. DESIGN: A prospective audit of process and outcome of care based on interviews with patients, abstraction from records with standard proforma, and follow up at three months. Data were analysed with chi 2 test and forward stepwise regression modelling of mortality. SETTING: All eight hospitals in East Anglia with trauma orthopaedic departments. PATIENTS: 580 consecutive patients admitted for fracture of neck of femur. MAIN OUTCOME MEASURE: Mortality at 90 days. RESULTS: Patients admitted to each hospital were similar with respect to age, sex, pre-existing illnesses, and activities of daily living before fracture. In all, 560 (97%) were treated surgically, by a range of grades of surgeon. Two hundred and sixty one patients (45%; range between hospitals 10-91%) received pharmaceutical thromboembolic prophylaxis, 502 (93%; 81-99%) perioperative antibiotic prophylaxis. The incidence of fatal pulmonary emboli differed between patients who received and those who did not receive prophylaxis against deep vein thrombosis (P = 0.001). Mortality at 90 days was 18%, differing significantly between hospitals (5-24%). One hospital had significantly better survival than the others (odds ratio 0.14; 95% confidence interval 0.04-0.48; P = 0.0016). CONCLUSIONS: No single factor or aspect of practice accounted for this protective effect. Lower mortality may be associated with the cumulative effects of several aspects of the organisation of treatment and the management of fracture of the hip, including thromboembolic pharmaceutical prophylaxis, antibiotic prophylaxis, and early mobilisation.
Asunto(s)
Fracturas del Cuello Femoral/mortalidad , Hospitalización , Anciano , Anciano de 80 o más Años , Antibacterianos/uso terapéutico , Anticoagulantes/uso terapéutico , Ambulación Precoz , Femenino , Fracturas del Cuello Femoral/cirugía , Mortalidad Hospitalaria , Humanos , Modelos Logísticos , Masculino , Auditoría Médica , Cuerpo Médico de Hospitales , Complicaciones Posoperatorias/mortalidad , Complicaciones Posoperatorias/prevención & control , Pronóstico , Estudios Prospectivos , Factores de Riesgo , Tasa de Supervivencia , Tromboembolia/mortalidad , Tromboembolia/prevención & control , Factores de TiempoRESUMEN
We developed a mathematical model of the reticulocyte, seeking to explain how a cell with similar volume but much higher ionic traffic than the mature red cell (RBC) regulates its volume, pH, and ion content in physiological and abnormal conditions. Analysis of the fluxbalance required by reticulocytes to conserve volume and composition predicted the existence of previously unsuspected Na(+)-dependent Cl- entry mechanisms. Unlike mature RBCs, reticulocytes did not tend to return to their original state after brief perturbations. The model predicted hysteresis and drift in cell pH, volume, and ion contents after transient alterations in membrane permeability or medium composition; irreversible cell dehydration could thus occur by brief K+ permeabilization, transient medium acidification, or the replacement of external Na+ with an impermeant cation. Both the hysteresis and drift after perturbations were shown to depend on the pHi dependence of the K:Cl cotransport, a major reticulocyte transporter. This behavior suggested a novel mechanism for the generation of irreversibly sickled cells directly from reticulocytes, rather than in a stepwise, progressive manner from discocytes. Experimental tests of the model's predictions and the hypothesis are described in the following paper.
Asunto(s)
Anemia de Células Falciformes/metabolismo , Agua Corporal/metabolismo , Electrólitos/metabolismo , Modelos Biológicos , Reticulocitos/metabolismo , Transporte Biológico , Permeabilidad de la Membrana Celular , Humanos , Concentración de Iones de Hidrógeno , Matemática , Potenciales de la MembranaRESUMEN
The power of mathematical cell models to predict novel behaviour concerned with the volume, pH and ion content regulation of red cells and reticulocytes is illustrated with three examples. Experimental results support the theoretical predictions.
Asunto(s)
Eritrocitos/fisiología , Modelos Biológicos , Reticulocitos/fisiología , Anemia de Células Falciformes/metabolismo , Animales , Cationes/metabolismo , Permeabilidad de la Membrana Celular , Hemoglobina Falciforme/fisiología , Humanos , Soluciones HipertónicasRESUMEN
In certain conditions, human red cell membranes spontaneously form inside out vesicles within 20 min after hypotonic lysis. Study of the geometry of this process now reveals that, contrary to earlier views of vesiculation by endocytosis or by the mechanical shearing of cytoskeleton-depleted membrane, lysis generates a persistent membrane edge which spontaneously curls, cuts, and splices the membrane surface to form single or concentric vesicles. Analysis of the processes by which proteins may stabilize a free membrane edge led us to formulate a novel zip-type mechanism for membrane cutting-splicing and fusion even in the absence of free edges. Such protein-led membrane fusion represents an alternative to mechanisms of membrane fusion based on phospholipid interactions, and may prove relevant to processes of secretion, endocytosis, phagocytosis, and membrane recycling in many cell types.
Asunto(s)
Endocitosis , Membrana Eritrocítica/fisiología , Exocitosis , División Celular , Humanos , Técnicas In Vitro , Fusión de Membrana , Microscopía Electrónica , Modelos Biológicos , Movimiento (Física)RESUMEN
Experiments were performed to test specific predictions of an integrated red cell model developed by Lew and Bookchin [Lew, V.L., Bookchin, R.M. J. Membrane Biol. 92:57-74 (1986)], that K-permeabilized human red cells suspended in low-K media would dehydrate and lose an alkaline, hypertonic fluid with excess K over accompanying anions, and that cell dehydration would precede medium alkalinization. Red cells were suspended at about 30% hematocrit in an initially K-free Na-saline and permeabilized to K by the addition of valinomycin. The results showed that by the time a quasi-steady state had been reached the cells had lost the equivalent of a hypertonic fluid containing about 180 mM KCl (SCN) and 10 mM KOH, and that cell dehydration did precede alkalinization of the medium, in good agreement with the theoretical predictions. Since these experiments critically test the interaction between transport, pH and volume regulatory functions in the human red cell, the observed agreement validates the basic assumptions and structure of the integrated model. The functional implications of these results are discussed.