Analysis of ERG a-wave amplification and kinetics in terms of the G-protein cascade of phototransduction

PURPOSE: To test rigorously the hypothesis that the a-wave of the electroretinogram (ERG) is proportional to the rod photocurrent by examining the applicability to a-waves of a recent model of the activation steps in the G-protein cascade of phototransduction. METHODS: ERGs were recorded in response to flashes of graded intensity, from six dark-adapted normal subjects and from two patients, one with retinitis pigmentosa (RP) and one with cone retinal dystrophy with rod involvement (CRD). The a-wave portions of the responses were analyzed with a model of the activation steps of the G-protein cascade. The model is characterized by a parameter, A, the amplification constant, with units of s-2 (per photoisomerization), which may be expressed as the product of physical and biochemical parameters of the transduction cascade. RESULTS: Each a-wave family was well described by the model. For the six normal subjects, we obtained A approximately 7 s-2, about 100-fold greater than in isolated amphibian rods at 22 degrees C, but close to the value for isolated primate rods. For the patient with RP, the maximum a-wave amplitude (amax) was considerably reduced, but the amplification constant was normal (A = 7.5 s-2). In contrast, the patient with CRD had a nearly normal amax but had an amplification constant about sixfold lower than normal (A = 1.1 s-2). CONCLUSIONS: The authors conclude that the a-wave is a direct reflection of the rod photo-current and that the rising phase kinetics are accurately described by a simple model of the G-protein cascade. They show that the small volume of the human rod outer segment is crucial to the achievement of high amplification, and they show how their observations constrain the possible pathologies of phototransduction in patients with retinal disease.     

Serum concentrations of neopterin, soluble interleukin 2 receptor, and soluble tumor necrosis factor receptor in Wegener's granulomatosis

OBJECTIVE: To investigate the possible relationship between serum levels of neopterin, soluble tumor necrosis factor-55 receptor (sTNF-55R), and soluble interleukin 2 receptor (sIL-2R) with disease activity in patients with Wegener's granulomatosis (WG). METHODS: Serum neopterin was measured by radioimmunoassay, sTNF-55R and sIL-2R were measured by ELISA in 26 patients with WG. RESULTS: Serum neopterin, sTNF-55R, and sIL-2R were significantly elevated in patients with generalized WG compared with healthy controls. Concentrations of the analytes correlated with disease activity indices in patients without infectious complications. The highest elevations of all 3 variables were observed in patients with intercurrent infections. CONCLUSION: The increased serum levels of neopterin, sTNF-55R, and sIL-2R suggest activation of cellular immunity in WG.     

The effect of x-ray contrast media on the amount of thromboxane and prostacyclin in the blood of man and rats in vivo and in vitro

The in vivo and in vitro effects of radioopaque agents such as bilignost, iodamide, and triombrast on blood thromboxane B2 (TxB2) and prostacyclin levels were studied in man and rats. These radioopaque agents were demonstrated to increase prostacyclin levels and to decrease TxB2 in the plasma by 40%, as evidenced by urography when given in vivo (1-2 g/kg) and in vitro (2.5.10(-2) M and 2.5.10(-3) M).     

Pediatric and adult lung transplantation for cystic fibrosis

OBJECTIVE: This paper was undertaken to review the experience at our institution with bilateral sequential lung transplantation for cystic fibrosis. METHODS: Since 1989, 103 bilateral sequential lung transplants for cystic fibrosis have been performed (46 pediatric, 48 adult, 9 redo); the mean age was 21 +/- 10 years. Cardiopulmonary bypass was used in all but one pediatric (age <18) transplant, and in 15% of adults. RESULTS: Hospital mortality was 4.9%, with 80% of early deaths related to infection. Bronchial anastomotic complications occurred with equal frequency in the pediatric and the adult populations (7.3%). One- and 3-year actuarial survival are 84% and 61%, respectively (no significant difference between pediatric and adult age groups; average follow-up 2.1 +/- 1.6 years). Mean forced expiratory volume in 1 second increased from 25% +/- 9% before transplantation to 79% +/- 35% 1 year after transplantation. Acute rejection occurred 1.7 times per patient-year, with most episodes taking place within the first 6 months after transplantation. The need for treatment of lower respiratory tract infections occurred 1.2 times per patient in the first year after transplantation. Actuarial freedom from bronchiolitis obliterans was 63% at 2 years and 43% at 3 years. Redo transplantation was performed only in the pediatric population and was associated with an early mortality of 33%. Eight living donor transplants (four primary transplants, four redo transplants) were performed with an early survival of 87.5%. CONCLUSION: Patients with end-stage cystic fibrosis can undergo bilateral lung transplantation with morbidity and mortality comparable to that seen in pulmonary transplantation for other disease entities.     

Cross-national HIV infection control practices and fear of AIDS: a comparison between Nigeria and the USA

Fears about occupational transmission of HIV may have a significant impact on the behaviour of health care workers and on infection control practices. We investigated the relationships between fear of AIDS and infection control practices in health care workers in major university teaching hospitals in Nigeria and the USA. Data from the fear of AIDS scale and on a measure of infection control practices and beliefs showed that knowledge of whether the patient was HIV-infected determined infection control practices in Calabar but not Texas. Where the patient was known to be infected, there were no differences between the 2 countries. Fears of AIDS were related to infection control practices significantly more in the USA than in Nigeria where there was almost no relationship. These data may be influenced by the greater availability of disposable equipment in the USA compared with Nigeria.     

Dystrophic and reparative changes in the cortical neurons of rat progeny in moderate prenatal alcoholization

Dynamics of dystrophic and reparative changes of sensorimotor cortex neurons ultrastructure in 21, 30 and 60-days progeny of rat treated with moderate doses of alcohol during pregnancy was studied with these changes found in mature cortical neurons having their own dynamics in postnatal ontogenesis. Dystrophic changes are better expressed until the age of a month. Signs of reparative processes increase with age, but hypoxically ischemic dystrophic neuronal changes remain up to puberty, which indicates effectiveness of moderate prenatal action of alcohol.