Nitrogen uptake in riparian plant communities across a sharp ecological boundary of salmon density.

BACKGROUND: Recent studies of anadromous salmon (Oncorhynchus spp.) on the Pacific Coast of North America indicate an important and previously unrecognized role of salmonid nutrients to terrestrial biota. However, the extent of this uptake by primary producers and consumers and the influences on community structure remain poorly described. We examine here the contribution of salmon nutrients to multiple taxa of riparian vegetation (Blechnum spicant, Menziesii ferruginea, Oplopanax horridus, Rubus spectabilis, Vaccinium alaskaense, V. parvifolium, Tsuga heterophylla) and measure foliar delta15N, total %N and plant community structure at two geographically separated watersheds in coastal British Columbia. To reduce potentially confounding effects of precipitation, substrate and other abiotic variables, we made comparisons across a sharp ecological boundary of salmon density that resulted from a waterfall barrier to salmon migration. RESULTS: delta15N and %N in foliage, and %cover of soil nitrogen indicators differed across the waterfall barrier to salmon at each watershed. delta15N values were enriched by 1.4 per thousand to 9.0 per thousand below the falls depending on species and watershed, providing a relative contribution of marine-derived nitrogen (MDN) to vegetation of 10% to 60%. %N in foliar tissues was slightly higher below the falls, with the majority of variance occurring between vegetation species. Community structure also differed with higher incidence of nitrogen-rich soil indicator species below the waterfalls. CONCLUSIONS: Measures of delta15N, %N and vegetation cover indicate a consistent difference in the riparian community across a sharp ecological boundary of salmon density. The additional N source that salmon provide to nitrogen-limited habitats appears to have significant impacts on the N budget of riparian vegetation, which may increase primary productivity, and result in community shifts between sites with and without salmon access. This, in turn, may have cascading ecosystem effects in forests adjacent to salmon streams.

An outbreak of Bacillus cereus respiratory tract infections on a neonatal unit due to contaminated ventilator circuits.

An outbreak of Bacillus cereus respiratory tract infections affecting six ventilated preterm neonates over a two-week period is described. Reusable ventilator circuits were identified as the cause of the outbreak. Ordinarily these were reprocessed on the Neonatal Unit (NNU), first through a washing machine and then through a low-temperature steam (LTS) disinfector. The onset of the outbreak coincided with a breakdown of the LTS facility, which necessitated sending the washed circuits off site for LTS disinfection. The washing machine was shown to be contaminated with the same serovars of B. cereus as those isolated from patients. Two critical steps in the off site LTS disinfection process allowed exsporulation and multiplication of B. cereus: the circuits were inadequately dried after processing, whilst return of the moist circuits to the NNU was often delayed. The outbreak was terminated by withdrawal of the heat-disinfected ventilator circuits. This outbreak emphasizes the need for high standards where medical equipment is reprocessed, especially for use in vulnerable patients.

Nosocomial infection with Rhizopus microsporus in preterm infants: association with wooden tongue depressors.

BACKGROUND: We report four cases of cutaneous infection with Rhizopus microsporus in vulnerable preterm infants in one neonatal nursery. METHODS: There was no overlap in hospital stay between the first two cases and an extensive programme of environmental sampling was therefore initiated, with special attention being paid to items that had close contact with infants' skin. Samples were cultured by standard techniques, including fungal culture with Sabouraud's medium. Filamentous fungi with non-septate hyphae were presumptively identified as agents of mucormycosis and referred to the Mycology Reference Laboratory, Bristol, UK, for speciation. FINDINGS: The source of infection was identified as wooden tongue depressors, which were used on the nursery to construct splints for intravenous and arterial cannulation sites. The outbreak was ended by the removal of these items from the nursery. INTERPRETATION: Wooden tongue depressors can be a vehicle for transmission of mucormycosis. The combination of warm, humid conditions in neonatal incubators, particularly in association with occlusive dressings, may favour cutaneous fungal invasion and put small, sick babies at risk of infection.

Paediatric use of intensive care.

OBJECTIVES: To determine the number of children from a defined population who use intensive care facilities, to analyse bed occupancy data for those children, and to estimate the number of intensive care beds required to satisfy this demand throughout the year. DESIGN: Examination of admission data books from intensive care units within the four Birmingham health authorities and the neighbouring health authorities. RESULTS: Two hundred and ninety seven children resident within the four Birmingham health authorities used intensive care facilities in a calendar year. One hundred and forty one (47%) of these were admitted for specialist paediatric services. Of the remaining 156, 106 (68%) were cared for in adult intensive care units, 46 (29%) in a paediatric intensive care unit and four (3%) in a special care baby unit. Use of intensive care varied from none to 11 patients each day, and was lowest in the summer and highest during the winter months. During periods of peak demand, one in 19,000 (5.3/100,000) children were using intensive care facilities. CONCLUSIONS: These data provide a population based minimum need for paediatric intensive care beds. They are higher than previous estimates and do not include provision for children from outside Birmingham, or for those denied intensive care due to bed shortages. These factors and the marked seasonal variation in demand need to be considered when planning intensive care services for children if bed shortages are to be avoided.

Simplified quantification of urinary protein excretion in children.

The protein/creatinine ratio (Up/Uc) measured in 71 early morning urine samples (EMU) correlated closely with timed overnight urine (ONU) protein excretion rates (r = 0.96). The relationship was linear throughout the entire range of normal and abnormal protein excretion, an ONU rate of 1 mg/h/m2 body surface area being proportional to an EMU Up/Uc of 5 mg/mmol. Using the Coomassie Blue dye-binding method the upper limit of Up/Uc in 377 apparently healthy children and adolescents aged 3-19 years was shown to be 20 mg/mmol. Albumin/creatinine ratios (Ua/Uc) were also determined in the 377 healthy subjects, yielding a normal working upper limit of 3 mg/mmol. Although in normal individuals studied longitudinally the day-to-day variation of both Up/Uc and Ua/Uc was appreciable, all measurements remained within the cross-sectional normal range. While the determination of Ua/Uc has a role in the study of "microproteinuria", it is comparatively costly for routine use. The measurement of the EMU Up/Uc avoids errors and difficulties associated with timed urine collection, simplifies sample handling by the laboratory and is inexpensive. In clinical practice this is the method of choice for the quantification of proteinuria in patients with renal disease.

Residual insulin secretion in adolescent diabetics after remission.

Twenty four hour blood glucose profiles were compared in two groups of insulin dependent adolescent diabetic patients who were beyond their initial partial remission phase. In the group with persistent endogenous insulin secretion, blood glucose profiles were significantly lower but the difference was small and not reflected in average 24 hour concentrations of glucose nor glycosylated haemoglobin. Endogenous insulin secretion must be considered in studies of metabolic control after the remission period but the effect on overall glucose control is probably clinically unimportant.

Use of human growth hormone in treatment of nesidioblastosis in a neonate.

Growth hormone was effective in reducing the glucose requirement in an infant with nesidioblastosis. He was suffering from fluid overload secondary to glucose and water infusions necessary to maintain blood glucose. Early pancreatectomy is the preferred treatment in severe cases, but human growth hormone has a place in preoperative management.

Metabolic rhythms in adolescents with diabetes during treatment with porcine or human insulin.

Metabolic rhythms were studied over 24 hours in eight adolescent diabetic patients during treatment with porcine insulin and after transfer to human insulin. Despite an increase in dose with human insulin no significant changes were found in fasting blood glucose, 24h mean blood glucose, or glycosylated haemoglobin concentrations. Significantly higher 24h mean blood lactate concentrations and lower total ketone bodies and glycerol concentrations were observed during treatment with human insulin. These findings are consistent with the increase in insulin dose and do not necessarily imply different metabolic responses to species differences in insulin.

Metabolic rhythms in adolescents with diabetes.

Metabolic rhythms were studied over 24 hours in eight adolescents with insulin dependent diabetes before and two months after attempting to improve diabetic control with home blood glucose monitoring. A significant improvement in blood glucose concentration was observed, although 24 hour mean concentrations remained grossly abnormal. This improvement was accompanied by significant falls in blood glycerol and total ketone bodies concentrations and a significant rise in blood lactate concentration. Without attention to other factors affecting diabetic control, the introduction of home blood glucose monitoring produces only a small improvement in control.