Requirement for ICR-like sequences in the replication of brome mosaic virus genomic RNA.

Previous studies using a brome mosaic virus (BMV) RNA-2 deletion mutant (pRNA-2 M/S) and additional derivatives as reporters established that viral sequences resembling internal control regions (ICRs) 1 and 2 of tRNA gene promoters are vital to (+)-strand replication in protoplasts. Transfer of these mutations to genomic RNA-2 and functional analysis in protoplast, local lesion, and systemic infections revealed a sequence-specific requirement for bases within the ICR2-like motif. Despite the low (generally less than 20% of wild-type) and sometimes undetectable levels of replication of these RNA-2 mutants, sufficient p2a protein was produced to support at least modest levels of RNA-1, -3 and -4 replication in protoplasts. However, only those RNA-2 ICR2 mutants supporting substantial replication of the viral genome in protoplasts were capable of establishing local lesions in Chenopodium hybridum and systemic infections in barley, further establishing the essential role of the ICR-like sequences in viral infectivity. Upon passage through a second set of barley plants, accumulation patterns for progeny from inocula containing certain RNA-2 mutants paralleled those from wild-type inocula, indicating repair of the introduced mutations. RNA stability and translatability were shown to be unaffected by the introduced mutations. BMV RNA-3 contains several ICR-like sequences, each of which was individually deleted. Whereas deletion of the 5'-terminal ICR2-like motif had little effect on RNA-3 accumulation in protoplasts or local lesion formation, it debilitated systemic spread in barley. Deletion of an internal ICR2-like motif at position 1100 decreased (+):(-) strand asymmetry from greater than 100:1 to 14:1, reduced RNA-3 replication in protoplasts to less than 15% of wild-type, and abolished local lesion and systemic infectivity.     

Atypical antiglomerular basement membrane disease associated with thin membrane nephropathy

Antiglomerular basement membrane (anti-GBM) disease is characteristically described with linear deposition of IgG along the GBM. We report two unusual cases of IgA and IgM anti-GBM disease associated with diffuse thinning of the GMB, and review the literature on atypical immunoglobulin species in this disorder. Both patients were male, aged 55 and 49 years, and presented with isolated microscopic haematuria, neither having shown evidence of impaired renal or pulmonary function on follow-up for 4 and 6 years respectively. Renal histology revealed minor focal mesangial changes only, but immunoperoxidase preparations demonstrated intense linear staining of the GBM with IgA in one case, and IgM with C3 in the other. On electron-microscopy there was diffuse thinning of the GBM in both cases, mean thickness 220 and 295 nm respectively (normal range 350-450 nm). Antinuclear antibodies were not detected and their glucose tolerance tests were normal. Assays for circulating IgG anti-GBM antibodies using indirect immunofluorescence (IF) and radioimmunoassay (RIA) were negative in both patients, although IgA anti-GBM antibodies with specificity confirmed by inhibition studies were identified in the first case. Thin GBMs in these patients may expose the Goodpasture antigen to toxic or infectious insults, thus altering its antigenic profile and promoting this unusual immune response.     

Portal venous velocity in biliary atresia

From December 1986 to April 1989, 38 patients with biliary atresia (eight newly diagnosed) were evaluated with doppler ultrasound of the portal venous system. Peak and mean velocities were computer derived from the spectral waveform. Good velocity was greater than 15 cm/s, intermediate velocity was 8 to 14 cm/s, abnormal velocity was less than 7 cm/s or hepatofugal. Patients were grouped according to clinical status: group 1 (n = 14), normal liver function; group 2 (n = 15), recurrent cholangitis; group 3 (n = 2), established bile drainage but complicated cirrhosis; group 4 (n = 7), failed portoenterostomy. All patients with normal liver function (group 1) had good or intermediate velocities. Thirteen of 15 patients with recurrent cholangitis (group 2) had good or intermediate velocities. Both patients in this group with abnormal velocities required transplantation. In group 3 the patient with abnormal velocity is on the transplant waiting list. In group 4, abnormal velocities preceded or coincided with deterioration of liver function in five of seven patients. Doppler ultrasound provides useful anatomic information, determines direction of flow, quantitates velocity of flow, and, when performed serially, provides adjunctive information on liver status in children with biliary atresia. These preliminary results suggest that patients with abnormal or significantly decreasing velocity are destined for transplantation. Patients with good portal venous velocity warrant ongoing, aggressive surgical management.     

A lethal skeletal dysplasia with features of chondrodysplasia punctata and osteogenesis imperfecta: an example of Astley-Kendall dysplasia. Further delineation of a rare genetic disorder.

An unusual osteochondrodysplasia presenting with lethal neonatal short limbed dwarfism, defective ossification, and punctate calcification within cartilage is presented. The features resemble four cases previously described with Astley-Kendall dysplasia.     

Ibuprofen overdose in adults.

A prospective study of 63 ibuprofen overdose cases in adults (14 years or older) reported to the Rocky Mountain Poison and Drug Center between March 1987 and February 1988 was done to determine the incidence of renal injury and utility of timed plasma levels. No serious toxicity was noted. No CNS or other significant toxicity was seen with ingestion of less than 3 g. Two patients with normal serum creatinines had minor elevations of the blood urea nitrogen after ingesting 4 and 4.8 g. Timed plasma levels (125 total) from patients without coingestants from this study (48) and previously published reports (77) were compared with a previously described nomogram. The resulting nomogram revision may be useful in determining which initially asymptomatic patients are likely to remain so. Renal function tests are not routinely required for patients ingesting less than 6 g. Four h of observation is sufficient for asymptomatic patients not requiring psychiatric admission. Plasma ibuprofen levels are not required for proper patient management.     

Best medical practice in practice: measuring efficiency in mammography screening.

Breast cancer, screening and mammography have caused considerable debate in several countries. This article explores the concept of best medical practice in the context of mammographic screening for breast cancer. Maximizing the use of technology, ignores the risks intrinsic to technological intervention. To do no harm in modern medical practice means largely doing nothing. Best medical practice, therefore, requires a balancing of benefits and risks so that best practice is that which does more good than harm. At the same time, not all interventions that do more good than harm can be funded out of the current health care budget. Thus, best medical practice is economically efficient practice. From the conceptual notion of what is best medical practice, this article turns to the problem of what that means in practical terms. Can we recognize best medical practice when it occurs? The identification, measurement and valuation of costs and benefits are discussed as a specific case study, in the context of breast cancer screening. Many of the difficulties involved here, particularly on the benefit side, are highlighted, especially in the context of QALYs. Yet, whatever the difficulties involved they have to be seen in the context of otherwise settling for something less i.e. inefficient medical practice.