Cadmium accumulation in and tolerance of rice (Oryza sativa L.) varieties with different rates of radial oxygen loss.

Cadmium (Cd) uptake and tolerance were investigated among 20 rice cultivars based on a field experiment (1.2 mg Cd kg⁻¹ in soil) and a soil pot trial (control, 100 mg Cd kg⁻¹), and rates of radial oxygen loss (ROL) were measured under a deoxygenated solution. Significant differences were found among the cultivars in: (1) brown rice Cd concentrations (0.11-0.29 mg kg⁻¹) in a field soil, (2) grain Cd tolerance (34-113%) and concentrations (2.1-6.5 mg kg⁻¹) in a pot trial, and (3) rates of ROL (15-31 mmol O2 kg⁻¹ root d.w. h⁻¹). Target hazard quotients were calculated for the field experiment to assess potential Cd risk. Significant negative relationships were found between rates of ROL and concentrations of Cd in brown rice or straw under field and greenhouse conditions, indicating that rice cultivars with higher rates of ROL had higher capacities for limiting the transfer of Cd to rice and straw.

Variations in regional SPECT hypoperfusion and clinical features in frontotemporal dementia.

OBJECTIVE: To characterize the presenting clinical features for frontotemporal dementia (FTD) and contrast them with the degree of frontal and temporal hypoperfusion on SPECT imaging. METHODS: The authors evaluated 74 patients who eventually met Consensus Criteria for the FTD form of frontotemporal lobar degeneration (excluding primary progressive aphasia and semantic dementia) on 2-year follow-up. On first presentation, these patients had undergone both an FTD Inventory for 12 features based on core and supportive Consensus Criteria and SPECT imaging. The initial clinical diagnostic features were contrasted with variations in regional SPECT hypoperfusion. RESULTS: The patients with FTD had more hypoperfusion in the right frontal lobe than in other regions; the subgroup of 25 patients who met Consensus Criteria from the first presentation had the most right frontal hypoperfusion. Frontal lobe involvement was associated with significant apathy, whereas temporal lobe involvement was associated with hypomania-like behavior. Right frontal lobe hypoperfusion further predicted loss of insight, environmental dependency, and stereotyped behaviors. Other associations included left frontal hypoperfusion with a decline in personal hygiene and left temporal hypoperfusion with compulsions and mental rigidity. CONCLUSIONS: On first presentation, frontotemporal dementia (FTD) is disproportionately a right frontal disease evident on behavioral measures and on SPECT. Nonetheless, patients with FTD can initially present with further regional differences in clinical diagnostic features, such as apathy with bifrontal hypoperfusion and hypomania-like behaviors with anterior temporal involvement.

Functional neuroimaging and presenting psychiatric features in frontotemporal dementia.

BACKGROUND: Frontotemporal dementia (FTD) is a behavioural syndrome caused by degeneration of the frontal and anterior temporal lobes. Behavioural disturbances include psychiatric features. Whether patients with FTD present with psychiatric features varies with the initial neuroanatomical variability of FTD. OBJECTIVE: To identify presenting psychiatric changes not part of diagnostic criteria of FTD and contrast them with the degree of hemispheric asymmetry and frontal and temporal hypoperfusion on single photon emission computed tomography (SPECT) imaging. METHODS: 74 patients who met consensus criteria for FTD were evaluated at a two year follow up. All had brain SPECT on initial presentation. Results of an FTD psychiatric checklist were contrasted with ratings of regional hypoperfusion. RESULTS: The regions of predominant hypoperfusion did not correlate with differences on FTD demographic variables but were associated with presenting psychiatric features. Dysthymia and anxiety were associated with right temporal hypoperfusion. "Moria" or frivolous behaviour also occurred with temporal lobe changes, especially on the right. The only significant frontal lobe feature was the presence of a peculiar physical bearing in association with right frontal hypoperfusion. CONCLUSIONS: Patients with FTD may present with psychiatric changes distinct from the behavioural diagnostic criteria for this disorder. Early temporal involvement is associated with frivolous behaviour and right temporal involvement is associated with emotional disturbances. In contrast, those with right frontal disease may present with alterations in non-verbal behaviour.

Proliferation of human ocular fibroblasts. An assessment of in vitro colorimetric assays.

Growing interest surrounds the pharmacologic modulation of ocular wound healing and fibroblastic proliferation. Therefore many investigators have developed assays to screen potential antiproliferative drugs on cultured fibroblasts. Such assays are extremely labor intensive, especially when many compounds are tested. Using proliferating human ocular fibroblasts, the authors explored the feasibility of three in vitro colorimetric assays as rapid, simple alternatives to more tedious proliferation assays, such as Coulter counting. These were: (1) the mitochondrial metabolism of a tetrazolium dye, (2) the cytoplasmic activity of hexosaminidase, and (3) the lysosomal uptake of neutral red, a weak basic dye. Serial dilutions of fibroblasts were assayed with each colorimetric technique; Coulter counting was used as a standard. All three colorimetric methods showed strong linear relationships between optical density and Coulter-cell counts. The MTT and neutral-red techniques were relatively insensitive, unable to quantify reliably fewer than 20,000 or 50,000 cells, respectively. On the other hand, the hexosaminidase assay was far more sensitive, reliably detecting a few hundred cells. Despite their differences and limitations, these three colorimetric techniques are useful as inexpensive screens whenever multiple drugs are tested for antifibroblastic effects.

Ascorbic acid inhibition of Campylobacter jejuni growth.

The inhibitory effect of ascorbic acid on Campylobacter jejuni is described. In vitro growth of clinical strains, as measured spectrophotometrically, was inhibited by 0.5 mg of freshly prepared L-ascorbic acid per ml. Alkaline-treated or aged L-ascorbic acid increased inhibition, as did copper; however, L-cysteine, L-cystine, and glutathione prevented inhibition. Biochemical analysis of the medium and cultures indicated that one or more of the oxidation products of L-ascorbic acid, e.g., L-dehydroascorbic acid or L-diketogulonic acid, were more effective inhibitors than was reduced L-ascorbic acid.

Potentiometric quantitation of glycerol using immobilized glycerol dehydrogenase.

Glycerol dehydrogenase was immobilized in polyacrylamide gel layered over a small platinum screen and used to catalyze the oxidation of glycerol. In the presence of NAD(+) and potassium ferricyanide, the coupling reaction generated a measurable electrical potential which was found to be Nernstian with respect to the glycerol concentration range of 10(-4)M to 10(-1)M. The reproducibility of the measurement and the optimal conditions for glycerol determination were described.

Potentiometric method for substrate analysis using immobilized NAD + -dependent oxidoreductase enzymes.

Two coenzyme-dependent oxidoreductases, glucose dehydrogenase and alcohol dehydrogenase, were immobilized in polyacrylamide gel over a platinum grid matrix and used as enzyme electrodes to measure their substrate concentrations in buffered aqueous solutions. The immobilized enzymes were used to oxidize their substrates in the presence of NAD +. Ferricyanide was used as the redox mediator and electroactive species. The determinations of glucose and ethanol were utilized to demonstrate and evaluate the performance of the system. The described methodology should be readily applicable to the analysis of numerous other substrates of coenzyme-dependent oxidoreductases.

Electrochemical evaluation of lactate dehydrogenase immobilized in polyacrylamide gels.

Lactate dehydrogenase (EC 1.1.1.27) has been immobilized in polyacrylamide gels over a platinum grid matrix. The immobilized enzyme is used to oxidize L-lactate in the presence of nicotinamide adenine dinucleotide (NAD+) and ferricyanide. The NADH produced is then chemically oxidized back to NAD+ by ferricyanide. The coupled reduction of ferricyanide ions to ferrocyanide ions results in a measurable electrochemical potential. This measurable zero-current potential is found to be Nernstian in nature and directly proportional to the logarithm values of L-lactate concentration over the range of 2 X 10(-5) to 5 X 10(-2)M. The results indicate that immobilized lactate dehydrogenase can be incorporated into a system to detect L-lactate acid in aqueous solutions.