Changes in elastic fibres in the small airways and alveoli in COPD.

Small airways are the major site of airflow obstruction in chronic obstructive pulmonary disease (COPD). This is attributed to loss of elastin in alveoli and fibrosis in small airways. In the present study, it was hypothesised that changes to elastic fibres in alveoli might be paralleled by a similar reduction in elastic fibres in small airways. Tissue blocks from patients who had lobectomy for bronchial carcinoma were studied. Patients were classified as COPD (forced expiratory volume in one second (FEV(1)) < 80% predicted, FEV(1)/forced vital capacity (FVC) < 0.7) or controls (FEV(1) > or = 80% pred, FEV(1)/FVC > or = 0.7). Elastic fibres were visualised using Elastic van Gieson staining and the volume fraction (v/f) of elastic fibres was determined as a percentage of tissue volume using point counting. Elastic fibre networks were also visualised by confocal microscopy. The v/f for elastic fibres in alveoli was 18.6% for COPD and 32.8% in controls. In the airways the v/f was 14.6% for COPD and 25.5% in controls. FEV(1)% predicted was correlated with v/f in both alveoli and small airways. The volume fraction of elastic fibres was reduced to a similar extent in small airways and alveoli in chronic obstructive pulmonary disease and both were correlated with the extent of airflow obstruction. Loss of elastic fibres in small airways may contribute to the development of airflow obstruction in chronic obstructive pulmonary disease.

Hip fracture mortality and morbidity--can we do better?

AIMS: To determine the mortality and morbidity from fractures of the neck of femur in Christchurch Hospital and to determine the extent that hip fracture patients are investigated and treated for osteoporosis. METHODS: All patients treated for a fractured hip at Christchurch Hospitals between May 1998 and April 1999 were identified. Their radiographs were reviewed and each fracture was classified. Dates of death were recorded where applicable. Surviving patients were contacted at least twelve months after their fracture and asked questions relating to functional outcome following surgery. The numbers of patients who had ever had a bone density scan, treatment for osteoporosis and/or a measurement of vitamin D were recorded. RESULTS: There were 331 fractures among 329 patients (242 women, 87 men), mean age of 79.7 (standard deviation 10.5) years. Twelve-month mortality was 26%. Men had a higher mortality rate than women for all fracture types that was independent of age. Follow up of the 231 surviving patients 12-24 months later revealed 27% still had pain and 60% had worsened mobility that they attributed to the fracture. Worsened mobility affected people living at home more than people living in institutional care. 32 people (15%) had had a vitamin D concentration measured and in 22 of these (69%) levels were below the reference range. CONCLUSIONS: The mortality and morbidity after hip fracture is high, especially in men. There were few significant correlates with greater morbidity except for fixation by hemi arthroplasty. More attention to hip fracture prevention is needed. Few subjects were on any therapy for osteoporosis other than calcium supplements. Vitamin D deficiency is an important but under-recognised condition.

Effects of varying 5-fluorouracil exposure duration on tenon's capsule fibroblasts.

PURPOSE: 5-Fluorouracil (5-FU) is used intraoperatively to improve the success of trabeculectomy Common practice is a 5-min application of 5-FU delivered via a Weck Cel sponge. The aim of this study was to determine if shorter exposure times were as effective in inhibiting Tenon's capsule fibroblast proliferation. METHODS: Samples of Tenon's capsules, obtained from young patients undergoing strabismus surgery, were immersed In vitro in 5-FU (50 mg/mL) for periods ranging from 1 to 10 min. Control samples were exposed either to growth medium (M 199) or 5-FU vehicle alone. Explants were cultured for up to 7 days and analysed for cell density, cell viability using fluoroprobe detection, and cell proliferation determined by proliferating cell nuclear antigen (PCNA)-staining. RESULTS: Exposure to 5-FU for 1 and 5 min resulted in a similar and significant inhibition of the culture-induced increase in stromal cell density (P < 0.01), a significant reduction in the percentage of viable cells (P < 0.02), and reduced PCNA indices, compared with controls. Exposure times of 3 and 10 min produced similar results. CONCLUSIONS: In vitro, under conditions of organ culture, a 1-min exposure to 5-FU had a significant antiproliferative effect on fibroblasts of Tenon's capsule, and was similar to 5 min of exposure. Optimal intraoperative 5-FU exposure time may be as little as 1 minute.

Comparison of deposits of versican, biglycan and decorin in saphenous vein and internal thoracic, radial and coronary arteries: correlation to patency.

BACKGROUND: Matrix proteoglycans versican, biglycan and decorin are important determinants of vessel-wall structure and pathology. Thickened myxoid intimas typical of restenosis and early atherosclerosis are enriched in versican and biglycan, proteoglycans that promote proliferation and migration of smooth muscle cells and bind lipoproteins. In contrast, compact fibrous intimas are characterized by decorin. OBJECTIVE: To compare the distribution patterns of these matrix proteoglycans, and changes induced by organ culture in coronary artery, saphenous vein, internal thoracic artery (ITA), and radial artery, and correlate differences to patency. METHODS: Vessels were collected at the time of bypass surgery and heart transplantation and either fixed for immunohistochemistry or prepared for organ culture. Vessels in culture were labelled with [3H]-glucosamine and processed for autoradiography and immunohistochemistry. Distribution patterns for proteoglycans and radio-labelling were determined morphometrically. RESULTS: Distribution profiles in coronary artery and saphenous vein were similar, with relatively high levels of subendothelial versican and biglycan and low levels of decorin. In culture subendothelial incorporation of [3H]-glucosamine and immunostaining for versican and biglycan, but not decorin, were significantly increased. In contrast, the thin intima of the ITA was relatively enriched in decorin compared with the medial layers and in culture intimal staining for decorin increased markedly compared with a modest increase for biglycan and no change for versican. There was an even distribution in radial artery of all three proteoglycans across the intima without subendothelial accumulations. In culture there was an increase in staining intensity for proteoglycans of the radial artery. Neither the ITA nor radial artery exhibited an increase in subendothelial incorporation of [3H]-glucosamine in culture. CONCLUSIONS: The distributions of proteoglycans, and responses to culture correlate to the known differences in patency between grafted saphenous vein and ITA and predict that the radial artery will outperform the saphenous vein but might not be as good as the ITA for long-term patency.

Effects of diary food supplements on bone mineral density in teenage girls.

BACKGROUND: Bone mineral density (BMD) is largely genetically determined and this influence is most powerful in the period of rapid skeletal development in childhood and late adolescence but environmental factors such as exercise and dietary calcium intake may influence up to 20%. AIMS OF THE STUDY: The aims of the study were to examine healthy late adolescent females for the effects and benefits of a high calcium intake from dairy product foods on bone mineral density, body composition, lipids and biochemistry. The secondary aim is determine whether a high intake of dairy product foods in the diet is acceptable for this age group long term. METHODS: Ninety-one teenage girls who participated in a two-year randomised controlled study on the effect of dairy food supplementation on dietary patterns, body composition and bone density in post-pubertal teenage girls were approached one year after the cessation of the study to determine the effects of the cessation of dairy supplements on bone mineral density, dietary habits, biochemical markers, body composition and blood lipids. Bone mineral density and bone mineral content were assessed at the hip, spine and total body. Anthropometric data were collected, and exercise, Tanner, dietary assessment, preference and compliance questionnaires were administered. Lipid profiles, hydroxyproline excretion and urinary calcium and sodium excretion measurements were performed. RESULTS: There were no significant differences between the 2 groups for height, weight, lean and fat mass. The supplemented group had significantly higher calcium, phosphorus and protein intake during the supplementation period (p < 0.001). No differences were seen between the groups 12 months after supplementation finished. There were no significant differences in exercise level, preference or acceptability of dairy products or in the lipids and bone markers between baseline the end of supplementation and 1 year follow-up. There was a significant increase in trochanter (4.6%), lumbar spine (1.5%) and femoral neck (4.8%) BMD (p < 0.05) in the high calcium group at the end of supplementation. There was an increase in bone mineral content at the trochanter (p < 0.05) and lumbar spine; however the latter was not statistically significant, in the high calcium group at the end of supplementation. There was no difference in vertebral height or width at any stage of the study, indicating no influence on bone size. CONCLUSIONS: In this 3 year study (2 years of supplementation, 1 year follow-up), teenage girls, aged 15-18 years, were able to significantly increase their BMD at the trochanter, femoral neck and lumbar spine when supplemented with dairy product foods to a mean calcium intake of 1160 mg/d. There was also an effect seen on the BMC particularly at the trochanter and to a lesser extent at the lumbar spine. The dietary calcium intake achieved did not adversely affect body weight, fat and lean mass or blood lipid profiles. Twelve months after the supplementation finished the girls had returned to their baseline diet, indicating self-selection of a high dairy product diet may be hard to achieve.

Environmental tobacco smoke and ischaemic heart disease: a case study in applying causal criteria.

BACKGROUND: Whether ischaemic heart disease (IHD) is caused by exposure to environmental tobacco smoke (ETS), commonly known as "passive smoking", has been debated from both epidemiological and biological perspectives. METHODS AND RESULTS: In this paper we use Bradford Hill criteria to synthesize results from the biological and epidemiological literature in a formal assessment of the strength of support for such a relationship. Although we find that these criteria, designed for clinical trials, do not give an ideal framework for assessment of epidemiological and biological studies, nevertheless they do provide systematic guidance for this assessment. For the general population, of the nine tests proposed by Hill we find that one (biological plausibility) seems to be supported, though not unarguably; three (strength, consistency. specificity) appear to fail by accepted standards; and the remaining five have insufficient data for a clear evaluation (biological gradient, experimental evidence, temporality, coherence, analogy). Overall, this provides at best weak support for a causal association between ETS and IHD across the general community. Conversely, there appears to be more support, especially in the biology studies, for an association between ETS and IHD for those with preexisting disease, although epidemiological studies are limited in this area. CONCLUSIONS: One of the outcomes of this review is the identification of areas of focus for future epidemiological and biological research. First, we find that stronger associations may be found in the particular subpopulation with pre-existing IHD. In this case, more convincing biological plausibility and experimental evidence indicate a need for relevant epidemiological studies, although individual responses are very variable. Second, we identify the need for further, more detailed evaluations of the nature of vessel wall thickenings occurring in experimental models of ETS exposure. Third, we propose long-term animal studies of initiation of IHD, including direct assessment of effects on the accumulation of lipid in vessel walls, at appropriate ETS exposure levels.

The prevalence of malnutrition in elderly hip fracture patients.

AIM: To determine the prevalence of protein and energy malnutrition in elderly patients with a fracture of the proximal femur, in New Zealand. METHODS: Consecutive elderly patients (65 years and over) admitted to Christchurch Hospital with a fracture of the proximal femur over a four-month period were recruited. Nutritional indices were measured within three days of admission. These included triceps skinfold thicknesses, mid upper arm circumference, serum albumin and pre-albumin. RESULTS: Forty-two per cent of patients had at least two, and nine per cent had three, indicators of protein and energy malnutrition present on admission. There was no significant difference in the prevalence of malnutrition between young old (<80 years) and old old (80 years and over) patients. Patients residing in an institution had lower mean protein reserves, as indicated by lower corrected arm muscle area (p=0.003) and pre-albumin levels (p=0.09), than those living in the community. A drink, rather than a pudding or biscuit, was the preferred protein and energy supplement form. Ensure Plus (lactose-free) and Fortisip (lactose-free) were the most preferred drink supplements. CONCLUSION: Protein and energy malnutrition is common in elderly New Zealanders who fracture their femur. The prevalence is comparable to overseas data. These patients prefer nutritional supplementation given as a drink.

Connective tissues: matrix composition and its relevance to physical therapy.

In the last 2 decades, the understanding of CT structure and function has increased enormously. It is now clear that the cells of the various CTs synthesize a variety of ECM components that act not only to underpin the specific biomechanical and functional properties of tissues, but also to regulate a variety of cellular functions. Importantly for the physical therapist, and as discussed above, CTs are responsive to changes in the mechanical environment, both naturally occurring and applied. The relative proportions of collagens and PGs largely determine the mechanical properties of CTs. The relationship between the fibril-forming collagens and PG concentration is reciprocal. Connective tissues designed to resist high tensile forces are high in collagen and low in total PG content (mostly dermatan sulphate PGs), whereas CTs subjected to compressive forces have a greater PG content (mostly chondroitin sulphate PGs). Hyaluronan has multiple roles and not only provides tissue hydration and facilitation of gliding and sliding movements but also forms an integral component of large PG aggregates in pressure-resisting tissues. The smaller glycoproteins help to stabilize and link collagens and PGs to the cell surface. The result is a complex interacting network of matrix molecules, which determines both the mechanical properties and the metabolic responses of tissues. Patients with CT problems affecting movement are frequently examined and treated by physical therapists. A knowledge of the CT matrix composition and its relationship to the biomechanical properties of these tissues, particularly the predictable responses to changing mechanical forces, offers an opportunity to provide a rational basis for treatments. The complexity of the interplay among the components, however, requires that further research be undertaken to determine more precisely the effects of treatments on the structure and function of CTs.

Detection of viable and non-viable cells in connective tissue explants using the fixable fluoroprobes 5-chloromethylfluorescein diacetate and ethidium homodimer-1.

The efficacy of connective tissue explants is difficult to determine, particularly where autopsy material is required for research or clinical applications. We report here an optimised protocol using 5-chloromethylfluorescein diacetate (CMFDA) and ethidium homodimer-1 to distinguish viable and non-viable cells in a range of connective tissue explants. Biopsies and explants of corneae, arteries, cartilage and skin were loaded with fluoroprobes for extended periods (< or = 24h) at low temperatures (4 degrees C), fixed in paraformaldehyde, and processed using a variety of embedding, sectioning, autoradiographic, and immunohistochemical procedures. Detection of fluorescent green CMFDA and red ethidium homodimer was achieved using epi-illuminated light or dual channel confocal microscopy, and clearly differentiated live from dead cells throughout the explants. Furthermore, the intracellular distribution of CMFDA provided superior images of cell shape and morphology not previously available using conventional histochemical techniques. Adaptations of this protocol could prove valuable in a variety of research and clinical applications.

Fluoroprobe quantification of viable and non-viable cells in human coronary and internal thoracic arteries sampled at autopsy.

Viable and non-viable cells in coronary and internal thoracic arteries, collected at autopsy 7-24 h post-mortem from individuals 15-81 years of age, were detected using the fixable fluoroprobes 5-chloromethylfluorescein diacetate (green) and ethidium homodimer-1 (orange/red). Viability status of individual endothelial and smooth muscle cells was confirmed by simultaneous autoradiographic detection of incorporated [3H]glucosamine. Twenty-five percent of coronary and 42% of internal thoracic arteries contained viable cells up to 24 h following death. For the majority of viable vessels the mean percentage of viable cells ranged between 60 and 80% with no significant difference between coronary and internal thoracic arteries and no relationship with either age of the donor or with time to autopsy. Non-viable cells were usually distributed fairly evenly amongst viable cells but this pattern could not be assumed. In a number of vessels non-viable cells were variably clustered in different regions of vessel wall. These findings confirm that vessels sampled at autopsy can be used for metabolic studies with the caveat that assessment of cell viability is a necessary prerequisite for interpretation of results.

Antisense S-oligonucleotide against transforming growth factor-beta 1 inhibits proteoglycan synthesis in arterial wall.

Transforming growth factor-beta 1 (TGF-beta 1) is a potent stimulator of proteoglycan (PG) synthesis by cultured smooth muscle cells. To test the hypothesis that TGF-beta 1 stimulates PG synthesis in whole artery wall we have investigated the effect of blocking endogenous TGF-beta 1 using an antisense S-oligonucleotide (ASO) directed against the first 7 codons for the N-terminal region of active TGF-beta 1. This sequence reduced TGF-beta 1 secretion by cultured endothelial cells by 40-55%. To determine the effect of the ASO on PG synthesis in whole vessel we chose the rat carotid artery (RCA) maintained in organ culture, a model in which we previously documented endothelial-dependent increases in PG synthesis over time in culture. We report here that the increases in PG in the inner layers of the vessel wall are matched by similar increases in TGF-beta 1 mRNA. To test for the effect of ASO on PG synthesis, small segments of RCA, maintained in organ culture (Medium 199, supplemented with 1% FCS), were exposed on day 6 to either control media, antisense TGF-beta 1, sense TGF-beta 1, or a non-sense sequence at 5, 10 and 20 microM concentrations. Following 24 h exposure to the oligonucleotides, cultures were labelled for a further 24 h with [3H]glucosamine and processed for autoradiography. Antisense TGF-beta 1 at 10 and 20 microM produced a 60% reduction in PG synthesis in the endothelium and adjacent first layer of the media.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural heterogeneity of the diffuse intimal thickening and correlation with distribution of TGF-beta 1.

This study examines the ultrastructural features of diffuse intimal thickenings of human coronary arteries and correlates structural heterogeneity along the radial axis with the distribution and known actions of transforming growth factor beta 1 (TGF-beta 1). Morphometric and immunohistochemical data were collected from thickenings of varying widths, sampled at autopsy from 19 persons ranging in age from 3 months to 81 years. Thickenings were characterised by an inner proteoglycan layer (PGL), up to approximately 70 mm wide, and an underlying variable-width musculofibrous layer (MFL). The PGL was characterised by low volume fractions (v/fs) for collagen, elastin, basement membranes and cells and a high v/f for matrix space; v/fs for the MFL components were more evenly distributed. Proteoglycans were visualised by ruthenium red staining, quantified and sized. Densities of large (versican; > 20 nm) and small (< 20 nm) granules changed little across intimal thickenings. Mean diameters of matrix space granules increased with increasing intimal thickness and notably were significantly (p < 0.001) larger in the PGL than the MFL. In contrast, diameters of collagen-associated small granules (decorin) did not differ between the PGL and MFL. TGF-beta 1 staining was detected in 70% of vessels examined and occurred almost exclusively in the PGL, although showed a patchy distribution. Both the distribution of TGF-beta 1 and its known differential effects on versican and decorin synthesis suggest that it may play a significant role in the formation and maintenance of the PGL.

Synthesis of TGF-beta 1 by vascular endothelial cells is correlated with cell spreading.

Cultured vascular endothelial cells (ECs) secrete transforming growth factor beta (TGF-beta) which stimulates intimal smooth muscle cells to synthesize increased amounts of lipoprotein-binding proteoglycans. We report here that the amount of TGF-beta 1 synthesized by ECs is correlated with EC density and cell spreading. ECs cultured at low density synthesized and secreted 2- to 3-fold more TGF-beta, measured by the Mink lung cell assay, than intermediate and high density cultures, and this increase in secreted protein was matched by a corresponding increase in mRNA for TGF-beta 1 measured by Northern hybridization using a [32P]-labeled cDNA probe for TGF-beta 1. TGF-beta 1 mRNA was detected in individual cells by in situ hybridization with the cDNA probe labeled with [35S] and with a [35S]-labeled 30-mer antisense oligonucleotide. In situ mRNA levels did not relate to cell density per se but to cell area. The larger the area of substratum covered, the more mRNA per cell, irrespective of cell density. For cell areas in the range 500-1,200 microns 2, a doubling of cell area resulted in an approximately 3-fold increase in mRNA. Cells cultured at low density had a larger mean cell area than cells cultured at higher densities, and this increased area was sufficient to account for the increased TGF-beta 1 mRNA levels found for the low density cultures by Northern hybridization. Despite variations in cell area, cell volumes did not change significantly with cell density.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycosaminoglycan synthesis by smooth muscle cells of differing phenotype and their response to endothelial cell conditioned medium.

The synthesis of glycosaminoglycans (GAG) by contractile and irreversible synthetic phenotypes of vascular smooth muscle cells (SMC), and their response to endothelial cell conditioned medium (ECCM), has been investigated. Contractile SMC, (with a high volume fraction of myofilaments) were obtained by culturing freshly isolated rabbit aortic SMC for 3 days in primary culture. Irreversible synthetic SMC (with a low volume fraction of myofilaments) were obtained by serially passaging SMC to achieve more than 5 cumulative population doublings. In fresh medium both phenotypes produced significant amounts of GAG, but irreversible synthetic cells were more than twice as active on a per cell and cell volume basis. The proportions of individual GAG also changed with change in phenotype. Hyaluronic acid (HA) was the predominant GAG (78%) synthesised by contractile SMC but was significantly reduced (47%) in the irreversible synthetic cells with a corresponding increase in sulphated GAG (SGAG). The changed levels in GAG synthesis were independent of SMC growth. Both phenotypes responded to ECCM from bovine endothelial cells (EC) and significantly increased their synthesis of GAG and by the same relative amounts (50-100%). This response was density dependent, with ECCM from low and high density cultures of EC producing maximal responses and EC of intermediate densities producing minimal increases. Furthermore, dense cultures of EC preferentially stimulated SGAG. These findings show that an increase in synthesis of SMC GAG, and especially sulphated GAG as is found in atherosclerosis, may occur either through a change in phenotype or through endothelial mediated stimulation of GAG synthesis by either phenotype.

Endothelial cell stimulation of smooth muscle glycosaminoglycan synthesis can be accounted for by transforming growth factor beta activity.

Endothelial cell conditioned medium (ECCM) contains a factor which markedly stimulates smooth muscle cell (SMC) glycosaminoglycan (GAG) synthesis. We report here that the factor responsible is transforming growth factor beta (TGF-beta) as assessed by (1) protease and thiol sensitivity, (2) heat and acid enhancement of ECCM activity, and (3) neutralisation of ECCM activity by anti-TGF-beta-immunoglobulin. Anti-TGF-beta-neutralisation was effective against increases in both sulphated and non-sulphated GAG. Previous studies showed that ECCM from EC of varying densities stimulated individual GAG to varying degrees. ECCM from low density EC preferentially stimulated hyaluronic acid (HA) whereas ECCM from intermediate and high density cultures stimulated increasing amounts of sulphated GAG. Exposure of SMC to varying concentrations of TGF-beta produced a similar pattern Exposure of SMC to varying concentrations of TGF-beta produced a similar pattern of response. Very low amounts of TGF-beta (less than 10-500 pg/10 cells) stimulated a marked and significant increase in HA synthesis. Increase in chondroitin sulphate 4/6 was most marked at TGF-beta levels from 500-1000 pg/10(6) cells. At levels above 1000 pg/10(6) cells both HA and sulphated GAG synthesis decreased but still remained elevated above controls. These findings indicate that TGF-beta alone can account for the changes in SMC GAG synthesis stimulated by ECCM. It was also found, however, that heat-treated SMC conditioned medium stimulated SMC GAG synthesis, thus SMC may contribute to the control of their own GAG synthesis through autocrine TGF-beta activity.

Structural features of saphenous vein and internal thoracic artery endothelium: correlates with susceptibility and resistance to graft atherosclerosis.

Examination of saphenous vein (SV) and internal thoracic artery (ITA) endothelium at the time of coronary bypass surgery has confirmed the known susceptibility of SV to endothelial cell loss during preparation for grafting. In contrast the ITA showed only minimal cell loss. An ultrastructural morphometric analysis of the abluminal surface of the endothelium of both vessels showed significant differences in the numbers and depth of penetration of cytoplasmic processes or folds. Whereas the SV, perfusion-fixed at 110 mmHg, possessed relatively few (15/100 micron) and shallow (less than 1 micron deep) processes the ITA had significantly more (27/100 micron) and deeper (18% greater than 1 micron) processes. The ITA endothelial cells were also smaller and thicker. We suggest that the differences in the numbers and depth of the processes, which are believed to play a role in endothelial attachment, may account for the differing susceptibility of the two vessels to endothelial damage during grafting. This in turn correlates with the known susceptibility of SV grafts and resistance of ITA grafts to atherosclerotic changes.

Stimulation of smooth muscle cell glycosaminoglycan synthesis by cultured endothelial cells is dependent on endothelial cell density.

Smooth muscle cells (SMC) cultured in the presence of endothelial cells (EC), or in EC-conditioned medium, show increased synthesis of glycosaminoglycans (GAG). We have found that both the amount and type of GAG produced by the SMC are dependent on the density of the EC. EC (porcine) at a low density (0.1-0.5 X 10(6) cells/25 cm2), or their conditioned media, where the most active per cell in stimulating GAG. All GAG were stimulated but the increase was due mostly to hyaluronic acid (HA). At intermediate densities (1.0 X 10(6)/25 cm2) stimulation was markedly reduced, but still present, and both HA and sulphated GAG were similarly increased. At high densities (1.5-3 X 10(6)/25 cm2) where EC were confluent there was very little stimulation of HA but continued stimulation of sulphated GAG synthesis. The shift in stimulation from HA to sulphated GAG with increasing density was most clearly demonstrated by the decrease in the HA to the chondroitin sulphate ratio. These findings provide support for the general concept that SMC metabolism may be affected by changes in the state of the endothelium.

Changes in collagen fibril diameters across artery walls including a correlation with glycosaminoglycan content.

Collagen fibril diameters were measured at regular intervals across the walls of numerous arteries from human, pig and rat. In all vessels the smallest fibrils (mean-fibril diameters of 30-40 nm) occurred in the intima and inner media and the largest fibrils (MFDs 50-100 nm) in the outer adventitia. Between these two regions fibrils progressively increased in size. Circumferential and axial fibrils were of similar size and showed similar patterns of increase. At each sample site there was a range of diameters and frequency distributions were often multimodal with peaks 8 nm, or multiples of 8 nm, apart. Amounts of total and individual glycosaminoglycans (GAG) were determined at regular intervals across the wall of pig aorta and total and sulphated GAG levels were also determined at intervals across rat carotid artery using autoradiographic detection of incorporated [3H] glucosamine and 35S. In both vessels there was a strong correlation between decreasing GAG and increasing MFDs and over a narrow MFD range of 40 to 60 nm. These results demonstrate that collagen fibril diameters are excellent indicators to GAG levels and may be useful for making predictions about GAG levels in areas too small to sample biochemically.

The effect of haemodynamic stress on the glycosaminoglycan content of blood vessel walls of experimental aneurysms and arteriovenous fistulae.

The glycosaminoglycan content of experimental saccular aneurysms and arteriovenous fistulae of sheep has been measured. In the experimental aneurysm hyaluronic acid, heparan sulphate, dermatan sulphate, chondroitin sulphate and total glycosaminoglycans were all elevated above control tissue levels with increases most striking for dermatan sulphate and chondroitin sulphate. In the anastomosed vein of the arteriovenous fistulae, total glycosaminoglycans were also significantly raised but which individual glycosaminoglycans were responsible was not clearly established. In the arteries feeding the fistulae, increased chondroitin sulphate in the proximal arterial segment was the only significant change observed. The changes were attributed to altered haemodynamic stresses and are similar to those reported for animal models of hypertension and early human atherosclerosis.