Nutrient attenuation by a riparian wetland during natural and artificial runoff events.

Due to chronic nutrient enrichment of surface water, wetlands adjacent to land managed with fertilizer have been studied to determine their role in nutrient dynamics. We sampled golf course runoff and determined the loads of NO3- and PO4(-3) transported during storms and the attenuation of those loads when runoff passed through a riparian wetland. All sampled storm events contained NO3- (2 to 1470 g NO3-N per event) and PO4(-3) (1 to 4156 g PO4-P per event). Extensive nutrient attenuation occurred when water passed through the riparian wetland. In 11 events, NO3- and PO4(-3) attenuation averaged 80 and 74%, respectively. In subsequent experiments, we created a stream of water flowing into the wetland and amended it with NO3-, PO4(-3) and Br-, creating an artificial runoff event. The experiments were conducted using conditions similar to those of natural runoff events. We observed rapid and complete attenuation of PO4(-3) immediately after runoff water infiltrated into the wetland subsurface. No PO4(-3) was observed in discharge from the wetland. Nitrate attenuation occurred following a lag phase of several hours that was probably due to reactivation of denitrifying enzymes. Nitrate attenuation was initially less than 60% but increased to 100% in all experiments. We observed extensive dilution of runoff water in the wetland subsurface indicating mixing with pre-event ground water in the wetland. The results indicated that intermittent inputs of NO3- and PO4(-3) could be successfully attenuated in the wetland on the time scale of natural storm events.

Mechanisms of nutrient attenuation in a subsurface flow riparian wetland.

Riparian wetlands are transition zones between terrestrial and aquatic environments that have the potential to serve as nutrient filters for surface and ground water due to their topographic location. We investigated a riparian wetland that had been receiving intermittent inputs of NO3- and PO4(3-) during storm runoff events to determine the mechanisms of nutrient attenuation in the wetland soils. Few studies have shown whether infrequent pulses of NO3- are sufficient to maintain substantial denitrifying communities. Denitrification rates were highest at the upstream side of the wetland where nutrient-rich runoff first enters the wetland (17-58 microg N2O-N kg soil(-1) h(-1)) and decreased further into the wetland. Carbon limitation for denitrification was minor in the wetland soils. Samples not amended with dextrose had 75% of the denitrification rate of samples with excess dextrose C. Phosphate sorption isotherms suggested that the wetland soils had a high capacity for P retention. The calculated soil PO4(3-) concentration that would yield an equilibrium aqueous P04(3-) concentration of 0.05 mg P L(-1) was found to be 100 times greater than the soil PO4(3-) concentration at the time of sampling. This indicated that the wetland could retain a large additional mass of PO4(3-) without increasing the dissolved P04(3-) concentrations above USEPA recommended levels for lentic waters. These results demonstrated that denitrification can be substantial in systems receiving pulsed NO3- inputs and that sorption could account for extensive PO4(3-) attenuation observed at this site.

Menkes disease after copper histidine replacement therapy: case report.

Menkes disease (MD) is an X-linked recessive disorder of copper metabolism, characterized in its untreated state by progressive disorders of multiple systems, especially the central nervous system (CNS) and connective tissue, and death by 3 years of age. Recently, therapy with copper-histidine has modified the severity of MD and permitted survival into adolescence. Clinical response has been greater for the neurological abnormalities than for the connective tissue abnormalities. In this report, we describe the postmortem pathology of one individual who had received copper-histidine therapy and died at age 10; we believe this to be the first such pathological report. The postmortem examination demonstrated significant pathology of mesenchymal tissues, including skeletal abnormalities, vascular degeneration, and bladder diverticula. The CNS, by contrast, showed minimal pathology. The phenotype was more consistent with occipital horn syndrome, a milder allelic disorder of copper metabolism, than with classic MD. The differential sensitivity of CNS and mesenchymal tissues to copper-histidine therapy may result from heterogeneity in the response of different copper-dependent enzymes.

Pathologic findings of multiple sulfatase deficiency reflect the pattern of enzyme deficiencies.

Multiple sulfatase deficiency is a rare metabolic storage disorder that manifests in childhood. It is probably an autosomal-recessive inherited condition, the gene for which has not yet been identified. Clinical features include mental deficiency and a dysmorphic appearance reminiscent of a mucopolysaccharidosis. Unlike most storage disorders, there are multiple deficient enzymes; all are sulfatases, hence the name of the disorder. Biochemical testing reveals accumulation of glycosaminoglycans, sulfatides, and gangliosides in the brain and other tissues of affected patients. In previous accounts of postmortem examinations, white matter histologic and biochemical pathologic findings similar to metachromatic leukodystrophy have been reported. Ganglioside accumulation, secondary to interference with degradative enzyme activity by the accumulating glycosaminoglycans also has been demonstrated. The authors report a case of multiple sulfatase deficiency with only mild deficiencies of the arylsulfatases but with severe deficiencies of iduronate sulfatase and heparan sulfamidase. Pathologic changes were more in keeping with a mucopolysaccharidosis, with minimal white matter changes and deposition of metachromatic material. The authors postulate that the mild leukodystrophic changes but striking features similar to a mucopolysaccharidosis are reflections of the pattern of enzyme deficiency. The pathology of multiple sulfatase deficiency therefore represents an overlap between a leukodystrophy and a mucopolysaccharidosis, with the relative contribution of each pattern apparently depending on the pattern of enzyme deficiency encountered in each patient.

Foetal alcohol syndrome in Saskatchewan: unchanged incidence in a 20-year period.

Despite major initiatives in public and professional education about foetal alcohol syndrome (FAS) in Saskatchewan in the last 20 years, its incidence rate has not fallen. The rate was 0.515 per 1,000 live births in 1973-1977 and 0.589 in 1988-1992. Two hundred and seven (207) cases were ascertained, the majority being patients of the Alvin Buckwold Child Development Program in Saskatoon. These individuals were severely handicapped: 72% had at least one malformation, the mean intelligence quotient was 67.8 (range 35-106) and 45.9% had a behaviour problem. Only 25.6% still lived with their biological parents when last seen, and only 27 of 108 cases were in a regular class at school without additional support being necessary. New approaches are needed to reduce the incidence of FAS. Emphasis should be placed on individual case-finding, counselling for high-risk women, and community development programs. We are currently attempting this through a provincial coordinating committee.

Chemical studies of phytoestrogens and related compounds in dietary supplements: flax and chaparral.

High-performance liquid chromatographic (HPLC) and mass spectrometric (MS) procedures were developed to determine lignans in flaxseed (Linum usitatissimum) and chaparral (Larrea tridentata). Flaxseed contains high levels of phytoestrogens. Chaparral has been associated with acute nonviral toxic hepatitis and contains lignans that are structurally similar to known estrogenic compounds. Both flaxseed and chaparral products have been marketed as dietary supplements. A mild enzyme hydrolysis procedure to prevent the formation of artifacts in the isolation step was used in the determination of secoisolariciresinol in flaxseed products. HPLC with ultraviolet spectral (UV) or MS detection was used as the determinative steps. HPLC procedures with UV detection and mass spectrometry were developed to characterize the phenolic components, including lignans and flavonoids, of chaparral and to direct fractionation studies for the bioassays.

Prenatal vitamin B12 therapy of a fetus with methylcobalamin deficiency (cobalamin E disease).

A child presented early in life with homocystinuria and megaloblastic anaemia which responded to hydroxocobalamin (OH-B12) therapy. Mental development has been subnormal since birth. Fibroblasts from this patient contained low levels of methylcobalamin (CH3-B12) and incorporated less 14C from labelled 5-methyltetrahydrofolate (14CH3H4PteGlu) into methionine. Methionine synthase activity was more thiol-dependent in the patient's fibroblasts than it was in normal cells. Studies on fibroblasts from the parents confirmed that both are heterozygous for this disorder. When the mother became pregnant again, prenatal diagnosis was attempted by use of cultured amniocytes obtained at 16 weeks' gestation. Values for incorporation of 14CH3H4PteGlu into methionine by intact cells and the thiol requirement of methionine synthase were abnormal in these amniocytes but these features did not conclusively identify the fetus at risk as being homozygous for the abnormality. Only 8% of the 57Co vitamin B12 incorporated by the fetal amniocytes was present as CH3-B12 compared with 29% and 40% in two control amniocyte lines and 37% and 32% in fibroblasts from the parents who are obligate heterozygotes. These studies suggested that the fetus had CH3-B12 deficiency. The mother was treated with OH-B12 (1 mg twice weekly, intramuscularly) from 25 weeks' gestation. The baby was clinically normal at birth without any evidence of homocystinuria or anaemia, and has been maintained on OH-B12 (1 mg twice weekly). Studies on fibroblasts from the baby confirmed the diagnosis of CH3-B12 deficiency (cobalamin E disease). At 6 months of age, growth and development remain normal.

Biochemical and clinical studies of a new case of alpha-aminoadipic aciduria.

A mentally retarded, 10-year-old female with obesity, hypotonia, clumsiness and mild ocular abnormalities excreted in her urine large amounts of alpha-aminoadipic acid. Amino acid analyser studies and gas-liquid chromatography--mass spectrometry (GC--MS) confirmed the presence of alpha-aminoadipic acid in both urine and plasma but, in contrast to most other patients with this disorder, failed to demonstrate significant levels of alpha-ketoadipic acid in urine. Other known causes of alpha-aminoadipic aciduria were eliminated by showing that levels of lysine, saccharopine and pipecolic acid in plasma and urine were normal and that the activity of glutaryl-CoA dehydrogenase was also normal. Loading with L-lysine and L-tryptophan both increased the concentration of alpha-aminoadipic acid in blood and urine compatible with the primary deficiency of alpha-ketoadipate dehydrogenase, in spite of the absence of alpha-ketoadipic aciduria. Dietary restriction of lysine and administration of vitamins B1 and B6 were unsuccessful in correcting the biochemical abnormality.