Response of plasma lathosterol concentration to change in the quality of dietary fat in men and women

OBJECTIVE

The aim of the study was to determine the effect of replacing saturated fatty acids (SAFA) with polyunsaturated fatty acids (PUFA) in the diet on plasma lathosterol concentration, an index of cholesterol synthesis, in mildly hypercholesterolaemic subjects.

DESIGN

The study was a randomised, cross-over trial.

SUBJECTS

Seventy-six subjects were recruited and one dropped out. Twenty-nine men and 46 women with baseline plasma cholesterol levels in the range 5.5-7.9 mmol/l were entered into the trial.

INTERVENTIONS

Subjects were placed on two isocaloric diets, one rich in SAFA and the other high in PUFA, for 6 weeks each. Plasma lathosterol and lipid and lipoprotein concentrations were measured.

RESULTS

When PUFA replaced SAFA in the diet, there was a significant (P = 0.01) fall in plasma lathosterol concentration in all subjects combined [-1.37 (-0.36 to -2.38) mumol/l] which was largely due to a significant (P = 0.03) decrease in men [-2.35 (-0.42 to -4.28) mumol/l] but not in women. The concomitant decreases in plasma cholesterol, low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol were similar in men and women. Plasma lathosterol concentration and the ratio lathosterol/cholesterol were significantly higher in men at baseline and during diets rich in SAFA but were not significantly different between the sexes during diets rich in PUFA.

CONCLUSIONS

These data suggest that replacing SAFA with PUFA in the diet may reduce cholesterol synthesis in mildly hypercholesterolaemic men and markedly reduce the gender-related difference in cholesterol synthesis commonly observed.

Water-soluble Abeta (N-40, N-42) oligomers in normal and Alzheimer disease brains

Ultracentrifugation and graded molecular sieving, as well as a sensitive sandwich enzyme-linked immunosorbent assay were used to isolate and quantitate the amounts of water-soluble oligomers of beta amyloid (Abeta) peptides N-40 and N-42 in cerebral cortex of normal and Alzheimer disease (AD) brains. AD brains contained 6-fold more water-soluble Abeta (wsAbeta) than control brains. The majority of water-soluble peptides in most AD cases was A beta N-42, representing 12 times the amount found in control brains. The wsAbeta was present in the form of monomers and oligomers ranging from less than 10 kDa to greater than 100 kDa. The amount of wsAbeta N-42 in AD brains is about 50 times greater than the level of soluble Abeta N-42 found in the CSF of AD patients. This disparity may be due to the rapid association of wsAbeta N-42 into fibrillar deposits and/or to the integrity of the anatomical barriers which separate the two extracellular spaces. In this paper, we consider soluble any form of Abeta which has not yet polymerized into its insoluble, filamentous form. This includes both the newly synthesized forms of Abeta and those peptides which may be loosely attached to insoluble filaments but which can, nevertheless, still be considered soluble. It has been previously shown that, once it has aggregated into its filamentous form, the Abeta peptides are resistant to disaggregation and degradation by a number of denaturing agents and aqueous buffers containing proteolytic enzymes. Therefore, it is likely that the water-soluble Abeta peptides we quantified are precursors to its insoluble, filamentous form. Consequently, reducing the levels of soluble Abeta in AD brains could have profound effects on AD pathophysiology.

Fat and calcium intake in women dieters

Low-fat diets are widely recommended to treat hyperlipidemia and obesity and to reduce the risk of coronary heart disease, but concern has been expressed that they may not provide adequate calcium. This study assessed the calcium intake of 247 women from Otago, New Zealand aged 50-65 y consuming a variety of diets. Calcium intake was not reduced in women consuming a lipid-lowering or weight-reducing diet compared with nondieters. Intake was also similar in women consuming < 25 - 30%, or > 33% of energy from fat, indicating that calcium intake is not specifically compromised in a low-fat diet. The mean calcium intake of 754 mg/d was, however, below that recommended, with 80% of women receiving < 1000 mg Ca/d and one-third < 600 mg. Thus, most women need to increase their calcium intake irrespective of dietary energy and fat intakes.

The library of the future: an informatics institution

As technology transforms how information is accessed, stored and disseminated, the concept of the library changes as well. In its plans for a new building to house both library and computing services, the University of Maryland at Baltimore (UMAB) will give physical form and organizational dimensions to this new concept of the library. UMAB's library of the future will be an 'informatics institution,' designed to accommodate new technologies that support problem-based learning in the health sciences curricula. This new library will embody the concept and the discipline of health informatics.

Oxidation of low density lipoproteins from patients with renal failure or renal transplants

Peroxidation of low density lipoproteins (LDL) may be involved in the development of atherosclerosis which is prevalent in patients with chronic renal failure and renal transplant recipients. We determined the copper ion catalyzed oxidation in vitro, vitamin E content, and chemical and fatty acid composition of LDL isolated from 38 patients with renal disease and 15 healthy subjects. Also the acute effect of hemodialysis treatment on LDL oxidation variables was tested. The lag time in conjugated diene formation during oxidation was significantly (P = 0.011) shorter in LDL from renal transplant recipients (66 min, N = 18) mainly due to significantly (P < 0.05) shorter times in women (47 min, N = 7), compared with healthy subjects (83 min, N = 15), patients on hemodialysis (91 min, N = 13) and patients treated by continuous ambulatory peritoneal dialysis (CAPD) (82 min, N = 7). The maximum rate and the extent of LDL oxidation were significantly (P < 0.01) lower in all patients with renal disease compared with healthy subjects. The triglyceride content of LDL was significantly (P < 0.001) higher in women with kidney grafts (7.3%) compared with levels in the corresponding men (5.3%) and healthy women (5.0%), and was correlated significantly with the lag time in LDL oxidation in renal transplant recipients (Spearmans r = -0.502, P = 0.034). The percentage oleic acid in LDL was significantly higher (P = 0.002) and the percentage linoleic acid was significantly lower (P = 0.046) in patients with renal disease, and may largely account for their lower rates and extent of LDL oxidation. Levels of the LDL oxidation variables and organic lipid peroxide content of LDL were not significantly different before and after hemodialysis and 24 hours later. These results suggest that LDL from women with renal transplants may be abnormally susceptible to oxidation possibly due to increased triglyceride content.

Cerebral microvessels in Alzheimer's have reduced protein kinase C activity

Protein kinase C (PKC) is an important intracellular signalling enzyme. Numerous studies have suggested that alterations in this enzyme occur in aging and dementia. The objective of this study was to examine PKC in the cerebral microcirculation in aging and Alzheimer's disease. PKC activity, amount, and isoform distribution were analyzed in microvessels from adult and aged rodents as well as from Alzheimer patients and nondemented elderly controls. PKC activity was lower in Alzheimer vessels than in vessels from control brains, despite the presence of similar levels of PKC enzyme. In contrast, both activity and enzyme levels in young and aged rats were comparable. The beta-isoform was present in both rat and human microvessels and there were no age- or disease-related alterations. The loss in activity in cerebromicrovascular PKC in Alzheimer's suggest that perturbations in phosphorylation signalling cascades may exist at the Alzheimer blood-brain barrier.

Cholesterol precursor concentration in plasma from patients with chronic renal failure or kidney grafts

Plasma lathosterol concentration which is an index of cholesterol synthesis rate was measured in 36 patients with chronic renal failure (CRF) including 13 who were dialysis independent, 12 receiving hemodialysis and 11 on continuous ambulatory peritoneal dialysis (CAPD), 17 renal transplant recipients and 27 healthy control subjects. Concentrations of plasma lathosterol were significantly (ANOVA p = 0.03) lower in all categories of renal patients excepting those treated by CAPD, compared with control values. In normolipidemic subjects (cholesterol < or = 6.50 mmol/l and triglycerides < or = 2.0 mmol/l) plasma lathosterol levels in hemodialysis patients and renal transplant recipients were still significantly (ANOVA p = 0.02) lower than control values. In transplant recipients, the plasma lathosterol/cholesterol ratio was significantly (p = 0.02) lower than those treated with azathioprine and prednisone compared with those treated with these drugs and cyclosporin. Significant (p < 0.001) positive correlations were recorded between plasma lathosterol concentration and plasma levels of apolipoprotein B (apoB) and very low density lipoprotein (VLDL) lipids in the renal patients. These data suggest that the rate of cholesterol synthesis may be low in undialysed and hemodialysed patients with CRF and in renal transplant recipients, particularly those treated with double therapy, and may be linked to the metabolism of apoB and VLDL.

Alzheimer disease amyloid proteins inhibit brain endothelial cell proliferation in vitro

Despite the close morphological association of beta-amyloid and vascular cells, the functional effects of amyloid in cerebral endothelial cells in Alzheimer's disease have not been assessed. In this study, effects of amyloid fractions purified from senile plaques of AD brains were compared to synthetic amyloid peptides for their ability to affect brain endothelial cells in vitro. Our results indicate that plaque-derived amyloid inhibit brain endothelial cell proliferation in vitro by 40%. This inhibition was specific for plaque-derived amyloid, was not evoked by synthetic A beta 1-40, and was not mediated by alterations in intracellular calcium levels. Amyloid fractions from AD brains, although not directly toxic to brain endothelial cells, inhibit endothelial replication in vitro and therefore could alter the ability of vessels to repair and regenerate after injury.

Enterprise systems

Looking to the next generation of hospital information systems (HIS), the paper first provides an overview of enterprise systems, including the concept, current developments, hospital perspectives, critical issues and requirements, and future value-added enhancements. The paper then focuses on efforts drawing upon existing expertise in these critical areas, including infrastructure, workstations, standards, computerized patient records, and security. It concludes by stressing the importance of collaborative efforts in the creating of the next generation of HIS, health information systems or HIS.

Proteolysis of A beta peptide from Alzheimer disease brain by gelatinase A

It has been recently reported that the 72 kDa proteolytic enzyme gelatinase A/type IV collagenase/matrix metalloproteinase 2 (MMP2) hydrolyzed the Lys 16-Leu 17 peptide bond of a synthetic decapeptide (YEVHHQKLVFF) representing the soluble A beta sequence of amino acid residues 10-20. Our aim was to test if this enzyme could also degrade the insoluble 40-42 residues long A beta peptides purified from Alzheimer Disease brain. Our results indicate that MMP2 hydrolyzes A beta 1-40 and A beta 1-42 peptides at Lys 16-Leu 17, at Leu 34-Met 35, and Met 35-Val 36 peptide bonds. These results suggest that MMP2 has the ability of degrading A beta of AD in vitro. If this hydrolysis also occurs in the brain's extracellular matrix, the enzymatic action of gelatinase a could prevent the generation of amyloidogenic A beta 1-40(42).

Brain N-acetyl-L-aspartic acid in Alzheimer's disease: a proton magnetic resonance spectroscopy study

This study was performed in order to measure changes in brain N-acetyl-L-aspartic acid (NAA) in post-mortem brain tissue in Alzheimer's disease (AD) in comparison to normal control subjects using the technique of magnetic resonance spectroscopy. Brain tissue was obtained at autopsy and frozen until use, from seven patients diagnosed according to current research criteria for AD and 7 control subjects. Detailed clinical evaluations were available for all the dementia cases. Representative brain samples were obtained from three neocortical regions and a limbic region (parahippocampal gyrus) in white and grey matter. NAA was quantified on perchloric acid extracts using proton nuclear magnetic resonance (NMR) spectroscopy. Regional NAA did not vary significantly with age. In AD, reductions were present in the grey matter of the neocortex but not in the white matter. Within the parahippocampal gyrus there were reductions in both tissue types; only cortical levels correlated with clinical scales of dementia severity. A pattern of increasing correlation was observed between dementia severity as measured by the mini mental state examination during life and NAA levels from brain areas of increasing pathological predilection in AD. These post-mortem studies show reductions in brain NAA in AD which correlate with dementia severity during life and which support the use of future in vivo NAA spectroscopic images in the evaluation of AD patients.

Reflotron cholesterol measurement in general practice: accuracy and detection of errors

Comparison of cholesterol determinations by nurses using a Reflotron analyser in a general practice setting showed a good correlation with plasma cholesterol determinations by wet chemistry in a clinical biochemistry laboratory. A limited number of comparisons did, however, give a much lower result on the Reflotron. In an experimental situation, small sample volumes (which could result from poor technique) were shown to produce falsely low readings. A simple method which may immediately detect falsely low Reflotron readings is discussed.

Quantitative analysis of lipofuscin and neurofibrillary tangles in the hippocampal neurons of Alzheimer disease brains

Using computer-enhanced image analysis, the amount of lipofuscin was measured in 500 hippocampal pyramidal neurons (regions CA2 and CA3) with and without neurofibrillary tangles (NFT), in brains of 10 patients with Alzheimer's disease (AD), as well as in 6 age-matched controls. The average content of lipofuscin in those cells from AD brains carrying NFT is only 10% of the total perikaryal area, whereas in the AD neurons free of NFT, and in age matched controls, lipofuscin amounted to 31 and 33% of cellular area, respectively. Measurements of lipofuscin's intrinsic autofluorescence confirmed this material to be three times more abundant in AD neurons without NFT and in controls. We propose that a breakdown in the capacity for making lipofuscin may result in the neuronal inability to store toxic waste. Such a defect could be responsible for the generation of NFT and ultimately may contribute to neuronal demise.

Building the library/information center of the future

Changes in the mission, roles, and infrastructure of academic health sciences libraries pose an enormous challenge to those designing and planning new library buildings. The library will be judged by its ability to respond to changing information dissemination patterns, changing missions, technologies not yet contemplated, and curricular trends, notably the rise of informatics and problem-based learning. Key questions are posed; the answers will shape library building now and in the future.

Nutrient intake and haematological status of vegetarians and age-sex matched omnivores

OBJECTIVE

The study was designed to investigate the nutritional intake and haematological status of adult vegetarians.

DESIGN

Cross-sectional comparison of vegetarians and age/sex-matched omnivores.

SETTING

Free-living community subjects.

SUBJECTS

Fifty vegetarians were recruited by local advertisement. Each vegetarian selected their own age/sex-matched 'friend' control.

OUTCOME MEASURES

Each subject completed a 12 day dietary record. Haemoglobin, red cell indices, and serum ferritin, B12 and folate were measured.

RESULTS

Protein, saturated fat and vitamin D intake were significantly lower in the vegetarians, particularly in the vegans. Dietary fibre was higher in the vegetarians, and intake of calcium and zinc was similar. Mean (SD) iron intake in the vegetarians and vegans of 16.8 (4.8) mg/day was significantly greater than that of the omnivores: 14.6 (4.3) mg/day (P = 0.02). All the iron consumed by the vegetarians was non-haem; for the omnivores 10% was haem iron. Serum ferritin concentrations were significantly lower in male vegetarians than omnivores; mean (SD): 36.6 (36.0) and 105.4 (78.7) ng/ml, respectively, P < 0.01; and significantly more had values below 12 ng/ml (P < 0.001), despite having higher iron intakes which exceeded the Recommended Nutrient Intake (RNI). Female vegetarians also had lower ferritin concentrations than omnivores; mean (SD) 13.6 (7.5) compared to 33.6 (54.3) ng/ml, P < 0.01, but similar numbers of women had values below 12 ng/ml (42% and 39%). The vegans all had B12 intakes below the RNI; and 35% of the long-term vegetarians and vegans had serum vitamin B12 concentrations below the reference range.

CONCLUSION

Although the vegetarians had diets nearer to the recommended diet with a lower fat and salt content, a significant number need advice to improve their haematological status. Recommended intakes of iron may also need to be higher for vegetarians, particularly men.

An international health/medical informatics programs database

The University of Maryland at Baltimore has established a database of health/medical informatics programs worldwide. Since 1991, IMIA's Working Group on Education and Training in Medical Informatics has provided guidance on critical issues of policy and purpose. At the Heidelberg/Heilbronn Working Conference in 1992 on Health/Medical Informatics education, representatives to WG1 and participants made suggestions regarding database intent, structure, and attributes.

Chemical characterization of A beta 17-42 peptide, a component of diffuse amyloid deposits of Alzheimer disease

A peptide corresponding to the amino acid sequence of A beta 17-42 (LVFFAEDVGSNKGAIIGLMVGGVVIA) was isolated from Alzheimer Disease patient brains containing large deposits of diffuse-type amyloid. Brain homogenates were lysed in SDS and submitted to high speed centrifugations. A beta peptides were purified by size exclusion chromatography on Superose 12 and TSK 3000 SW columns. An A beta peptide with M(r) of 3,000 was recovered that on automatic gas-phase Edman degradation yielded the amino acid sequence of A beta starting at residue 17 (Leu). The 3-kDa peptide was subsequently hydrolyzed with trypsin and reacted with CNBr, and the resulting peptides were separated by reverse phase high pressure liquid chromatography and characterized by amino acid analyses, peptide microsequencing, and mass spectrometry. Hydrolysis of beta-amyloid precursor protein 695 at Lys612-Leu613 or at Lys16-Leu17 of its A beta 1-42 derivative prevents the generation of neurotoxic A beta filaments, thus leading to the formation of A beta 17-42 localized in the diffuse amyloid deposits. An outstanding feature in the pathology of Alzheimer Disease is that the predominant A beta peptides have their C termini at position 42, whether in the cores of the neuritic plaques, in the vascular walls, or in the diffuse deposits. Based on these observations, we postulate that the accumulation of insoluble A beta N-42 in Alzheimer Disease is due to the anomalous processing of the C-terminal region.

The professional workstation as enabler: conference recommendations. International Medical Informatics Association

This paper reports on the Working Conference on Healthcare Professional Workstation sponsored by the International Medical Informatics Association (IMIA) and held in Washington DC, 14-16 June 1993. It sets forth the vision of a health care infostructure in which the workstation acts as enabler, giving professionals access to information when, where, and how it is needed. The paper explains upon the conference methodology and provides the conference cochairs' summary recommendations, both short- and long-term. These recommendations are based upon the work of five breakout groups, which addressed Functional Requirements, User Interfaces, Data and Knowledge Management, Processing, and Sharing and Communications. Presented in detailed and display formats, these summary recommendations address issues in the areas of architecture, linkages, evaluation, security, standards, education, and training. The paper also sets forth immediate next steps for the workstation initiative, including the formation of a formal IMIA Working Group on Workstations.

Increased accumulation of cAMP in cerebral microvessels in Alzheimer's disease

The objective of this study was to compare the adenylyl cyclase-cAMP second messenger system in cerebral microvessels isolated from Alzheimer's patients to that in microvessels from nondemented elderly controls. To evaluate the role of aging separate from the effects of dementia, microvessels from young and aged rodents were also examined. The results of this study indicated that microvessels isolated from autopsy material can be used to evaluate adenylyl cyclase activity. The data showed that cAMP levels, as an index of adenylyl cyclase activity, are significantly (p < 0.02) elevated in microvessels from Alzheimer's disease compared to nondemented elderly controls. Stimulation of adenylyl cyclase by forskolin was comparable in both groups of microvessels. A comparison of unstimulated microvessels from young and aged rodents yielded no significant difference in cAMP levels. These results indicate an increased level of cAMP in the microvessels of Alzheimer's patients with no age-related change demonstrable in rat microvessels.

Trans fatty acid content of margarines, oils and blended spreads available in New Zealand

Concern has been expressed about the possible adverse effects of high intakes of trans fatty acids on coronary heart disease risk. Data on New Zealand foods was very sparse. The fatty acid composition of New Zealand margarines, cooking oils, blended spreads and dairy products has thus been analysed using a methodology that determines the percentage of trans fatty acids. The C18: 1 trans content of the margarines varied between 4.8% and 11.3% of the total fatty acids, and there was less than 0.7% C18:2 trans. The total trans fatty acid content of the oils analysed was less than 1%. The amount of trans fatty acids in readily available margarines, blended spreads and oils in New Zealand appears lower than for many other countries, and the intake of these products is relatively small. Most of the products also have a high linoleic acid content, which may modify any potential adverse effects of trans fatty acids on plasma lipoproteins. Replacement of products high in C12, C14 and C16 saturated fatty acids in the diet with these margarines need not be discouraged, although manufacturers should probably be encouraged to further reduce the content of trans fatty acids of some products and the increased use of partially hydrogenated fats in fast food restaurants should be examined.