Blur adaptation: clinical and refractive considerations

The human visual system is amenable to a number of adaptive processes; one such process, or collection of processes, is the adaptation to blur. Blur adaptation can be observed as an improvement in vision under degraded conditions, and these changes occur relatively rapidly following exposure to blur. The potential important future directions of this research area and the clinical implications of blur adaptation are discussed.     

Distribution of organic matrix in calcium oxalate renal calculi

Summary The quantity of protein and carbohydrate comprising the matrix of calcium oxalate monohydrate (COM) renal stones was found to decrease with distance from the surface of the stone. The average organic concentration of stones 3 to 30 mm in diameter ranged from 5.7% at the surface to 2.7% at the core. This concentration gradient suggests matrix involvement in a “growth front” on stone surfaces with migration of organic material from the “older” interior. The matrix distribution was not readily correlated with density variations or with the presence of hydroxyapatite or calcium oxalate dihydrate. Surface matrix concentrations were greater than amounts predicted by physical adsorption. Electron microscopy confirmed the presence of the organic-rich surface layer and also suggested that increase in stone size occurs predominantly by crystal growth with microcrystal aggregates as growth centers.     

Antibiotic prophylaxis and secondary haemorrhage following transurethral resection of the prostate: a prospective trial

One hundred and sixty-two patients were studied in a random double-blind controlled trial of co-trimoxazole to prevent secondary haemorrhage following transurethral resection of the prostate (TURP). There was a significant correlation between the incidence of post-operative urinary infection and secondary haemorrhage (P less than 0.05) but no difference between the incidence of bleeding in the treatment and placebo groups. Although infection may play a role in the development of secondary haemorrhage, co-trimoxazole for 10 days does not decrease the incidence of this complication.     

Lack of late-phase airway responses in conscious guinea pigs after a variety of antigen challenges

Guinea pigs were actively sensitized by parenteral injections of ovalbumin (OA), house dust extract (HD) orAscaris suum extract (As) in a variety of multidose regimens. At least 3 weeks after the initial sensitization injection, aerosols of the appropriate antigen were administered to conscious guinea pigs in a double-chamber body plethysmograph. OA elicited the most consistent and intense bronchoconstriction (BC) as measured by decreases in specific airway conductance (sGAW). The airway responses to As were clearly separable into responders and nonresponders. HD produced essentially no BC. However, intense lacrimation and rhinorrhea occurred in all HD-sensitized, but not unsensitized, animals. No late-phase changes in sGAW or increased reactivity to other spasmogens were seen up to 8h after any antigen challenge. Eosinophil influx of magnitude similar to that measured by 24h post-antigen bronchoalveolar lavage (BAL) occurred with all the three antigens. Animals which did not bronchoconstrict to As experienced an equal or greater pulmonary eosinophilia as airway responders. The present data with HD and As suggest that acute BC in response to antigen provocation is not a prerequisite for the eventual pulmonary eosinophilia. The lack of late-phase airway reactions in these models raises a doubt in the direct extrapolation to airway responses in allergic human asthma. The acute lacrimation and rhinorrhea to HD may suggest utility as a model of allergic rhinitis.     

Risk factors for Caesarean section in Italy: results of amulticentre study

A recent large increase in Caesarean section (CS) in Italy was the initial stimulus for a study to identify risk factors for CS and, if possible, to suggest strategies to counteract the rise. The study was conducted in three hospitals where a wide range of individual variables was collected from the clinical records and from personal interviews. Crude CS rates and odds ratios were evaluated for each single variable while logistic regression has been used to investigate possible confounding factors. The study involved 1316 consecutive deliveries. Crude CS rates were 29.4%, 15.7% and 16.1%. Variables identified as high risk factors were pre-eclampsia, previous CS, breech and other non-vertex presentations. Antenatal care under an obstetrician working in the same hospital, a low number of antenatal consultations, previous miscarriages, offer (by obstetrician) and request (by women) for CS showed significantly high odds ratios (ORs). Previous live births was strongly negatively associated with CS. No relationship between type of delivery and social status was observed while a physician factor was detected in all three hospitals where rates for different physicians ranged from 0% to 52.8%. Apart from the main medical indications for Caesarean section (previous CS, breech presentation), the results seem to indicate that individual practice style may be an important determinant of the wide variation in the rates of Caesarean delivery. While this may have been suspected before this study, these results are the first hard data to indicate that, in Italy, CS is widely performed for non-medical reasons.     

Serum ionic fluoride levels in haemodialysis and continuous ambulatory peritoneal dialysis patients

High serum fluoride (F-) in patients with chronic renal failure (CRF) and end-stage renal disease (ESRD) is associated with risk of renal osteodystrophy and other bone changes. This study was done to determine F- in normal healthy controls and patients with ESRD on haemodialysis (HD) or peritoneal dialysis (PD). Seventeen healthy controls (12 males, 5 females) and 39 ESRD patients on dialysis (17 males, 22 females) were recruited in the study in a community with 47.4 +/- 3.28 microM/l (range 44-51 microM/l) of F- content in drinking water. Control subjects showed a mean serum F- concentration of 1.08 +/- 0.350 microM/l. Males in control group showed slightly higher F- levels (1.15 +/- 0.334, range 0.55-1.9 microM/l) than females (0.92 +/- 0.370, range 0.6-1.5 microM/l). Mean serum F- concentration did not correlate significantly with age and sex among control subjects, whereas such correlation was observed in patients with ESRD on dialysis. Mean serum F- concentration was significantly higher in patients on dialysis (2.67 +/- 1.09, range 0.8-5.2 microM/l) than normal controls. When grouped according to sex, the mean serum F- concentration in males (3.05 +/- 1.04, range 1.8-5.2 microM/l) was significantly higher than females (2.38 +/- 1.08, range 0.8-5.2 microM/l). When patients were grouped according to age, it was observed that F- concentration was significantly higher in patients with age groups 21-70 (2.86 +/- 1.05) than those with age group 13-20 years (1.42 +/- 0.531). Thus F- concentration correlated with age and sex, being higher in males and above 20 years. Despite appreciable clearance of F- (39-90%) across the peritoneum, patients on CAPD showed higher serum F- concentration than those on HD (3.1 +/- 1.97 vs 2.5 +/- 1.137 microM/l). Of the total 39 patients on dialysis 39% had their serum F- concentration above 3.0 microM/l, posing the risk of renal osteodystrophy.      

Radiology administration: a reference list.

This useful listing of references on radiology administration covers topics from equipment selection to computerization. In addition to available written references, the authors provide information on PC-based access to data bases.