Fat-containing uterine smooth muscle cells in "toxemia": possible relevance to atherosclerosis?

Uterine smooth muscle cells in "toxemia of pregnancy" contain varying amounts of fat--a feature to date believed to characterize only the arterial smooth muscle cells in atherosclerotic lesions. Thus, the smooth muscle cells at these two sites do not differ essentially in their reactivity to certain forms of injury: hypoxia may represent an injurious factor common to both "toxemia" and atherosclerosis. These observations imply that the view that the arterial smooth muscle cells are biologically different than are those elsewhere may no longer be tenable.

The effect of ascorbate on the synthesis of minor (non-interstitial) collagens by cultured bovine aortic smooth muscle cells.

Ultrastructural and biochemical studies were carried out on bovine aortic smooth muscle cells cultured in the presence or absence of ascorbate. In its absence, electron microscopic examination of cultures revealed that the extracellular components consisted primarily of microfibrils. Morphologically identifiable collagen fibrils were only observed in the matrix upon ascorbate supplementation. Smooth muscle cells grown in ascorbate-free media synthesized large amounts of type VI collagen. The identity of the latter was confirmed by ion exchange chromatography, slab gel electrophoresis, and amino acid analysis. Addition of ascorbate resulted in a stimulation of type I collagen production, levels of the type III remained constant, and types V and VI were decreased. Since, in the absence of ascorbate, smooth muscle cells are known to synthesize predominantly elastin, the present data support the contention that the type VI collagen and the microfibrillar component of elastic tissue are either identical or similar.

Myogenic foam cells in explants of fatty dots and streaks from rabbit aorta. Morphological studies.

Present studies indicate that in explants of early atherosclerotic lesions removed from aortae of young rabbits on a 1% hypercholesterolemic diet for four and seven weeks respectively, myogenic foam cells (MCF's) were capable of emigrating into the culture medium and maintained their ability to produce microfibrils, elastic tissue elements, and collagen fibrils. In explants of the smallest lesions (fatty dots and small streaks) the MFC's divided prior to, or while emigrating. At the interphase between the primary tissue and the culture medium they contained in intracytoplasmic vacuoles fragments of elastic tissue and extraneous substances which were reminiscent of cellular debris. It is possible that this phenomenon represents a true phagocytic property of the MFC's. All formed extracellular connective tissue components were also produced by the emigrated MFC's in the tissue surrounding the cellular outgrowth. In the large fatty streaks cell division was observed at the interphase between the tissue and culture medium, but not within the substance of the explant; here cellular necrosis was prominent. The fat inclusions in the MFC's of explants and the outgrowth had the appearance of conglomerateds of unorganized, and only at times concentric, membranous profiles rather than that of homogeneous droplets observed by electron microscopy in these cells in tissue sections. In the outgrowth from explants of normal aortic areas adjacent to the lesions a moderate number of smoot muscle cells contained fat inclusions; these were almost totally absent in cells of the primary aortic cultures from normal aortae. It is conceivable that the migratory and phagocytic properties of the MFC's observed in the present study relate to some aspects of regression of atherosclerotic lesions; this, however, remains highly speculative at present.

Ciliated smooth muscle cells in aortic atherosclerotic lesions of rabbit.

Single rudimentary cilia were observed by electron microscopy in smooth muscle cells (SMCs) of aortic fatty streaks in hypercholesterolemic rabbits, but not in aortae of controls. Similar cilia are known to occur in several tissues and various species, but it is believed that they have not so far been identified in the SMCs of atherosclerotic lesions. These cilia differ structurally from the classical type characterising ciliated epithelium. It is currently thought that a sudden transformation from mitotic replicative to nonmitotic structuring tissue may be correlated with the disappearance of centrioles and formation of cilia. The possible implications of the above concept in the overall process of atherosclerosis in the context of our present-day knowledge is briefly discussed.

Characterization of basement membrane collagens of bovine aortae.

Collagenous components were extracted from bovine aorta by pepsin digestion. Differential salt precipitations separated the interstitial from the basement membrane (BM) collagens, and the latter were subsequently separated into three distinct types. Ion exchange chromatography, SDS-slab gel electrophoresis, cyanogen bromide and protease V8 peptide mapping, and amino acid analysis were used to characterize the component chains within each of these types. The major BM-class contained three distinct chains which were identical to the alpha 1(V), alpha 2(V) and alpha 3(V) chains of type V collagen from normal human placenta. The stoichiometry of the chains suggests a [alpha 1(V)]2 alpha 2(V)-helical organization, but the role of the alpha 3(V) chain in the overall structural organization of collagen V remains unknown. The second BM-class contained a heterogeneous group of molecules ranging in size from 40 000 to 140 000 daltons. Two predominant chains within this group were characterized as the alpha 1(IV) and alpha 2(IV) chains of type IV collagen. The last class of BM collagens consisted primarily of high molecular weight components; upon reduction these gave rise to two low molecular weight collagenous species (40 K and 45 K) characteristic of type VI, low molecular weight or 'linker' collagens. The functional roles of the isolated BM collagens, either individually or collectively, has not been ascertained to date.

Hemodynamic modification of aortic atherosclerosis. Effects of propranolol vs hydralazine in hypertensive hyperlipidemic rabbits.

According to hemodynamic theories of atherogenesis, atherosclerotic plaques are a reaction to endothelial damage caused by arterial flow disturbances such as turbulence. Earlier studies showed that hydralazine increased, whereas propranolol decreased, the product of heart rate X blood velocity, a predictor of arterial flow disturbances, and that hydralazine aggravated, whereas propranolol decreased turbulence in the region of carotid artery stenosis. This study was done to test the hypothesis that drugs which reduce arterial flow disturbances may be more effective in preventing atherosclerosis, than antihypertensive drugs which worsen arterial flow disturbances. Eighty-three New Zealand white rabbits were made hypertensive by a one-kidney Goldblatt procedure, and were fed a 1% cholesterol diet. Untreated hypertensive (P less than 0.01) and hydralazine-treated hypertensive rabbits (P less than 0.05) had significantly more atherosclerosis than did the normotensive controls; propranolol-treated rabbits did not differ significantly from the normotensive controls. Analysis of covariance showed that propranolol-treated rabbits had significantly less atherosclerosis than hydralazine-treated rabbits with blood pressure (P less than 0.04) or heart rate (P less than 0.006) as the covariates.

Cellular localization of metallothionein in human term placenta.

Cellular localization of metallothionein (MT) in placenta may provide information on its function as a metal binding protein. Rabbit antibodies to rat liver MT cross-reacted with human MT and were used to localize MT in human term placenta by avidin-biotin peroxidase technique. Serial sections (5 microns) were cut from paraffin-embedded placentae obtained at term from five normal women and incubated with rabbit antibodies to MT. Normal rabbit serum was used as a negative control. The slides were incubated with biotinylated swine anti-rabbit IgG (linking antibody) then with avidin-biotin horseradish peroxidase complex and developed with diaminobenzidine in hydrogen peroxide (0.03 per cent) substrate. The optimum staining of MT was obtained at a 1:800 antibody dilution. MT was identified in fetal amniotic cells, syncytial trophoblasts and villous interstitial cells, and in maternal decidual cells. The presence of MT at specific cellular sites suggests that it may regulate the transplacental transport of metals such as zinc, copper and cadmium. Since the level of cadmium is lower and that of zinc and copper higher in fetal than in maternal blood, this may suggest that placental MT may restrict cadmium while enhancing zinc and copper transport.

Morphometric studies of fetal placental stem arteries in hypertensive disorders ('toxaemia') of pregnancy.

The mural thickness of fetal stem arteries of 3rd order was assessed morphometrically in 50 placentae from each of the 'toxaemia', normal pregnancy and acute fetal distress groups. Several clinical maternal and fetal variables and the syncytial sprout proliferation of the placentae were correlated with the morphometric findings. The results show that: (1) there was a significant reduction in the ratio of lumen-to-whole-diameter of the fetal arteries in 'toxaemia' as compared with the two other groups; (2) the mean lumen-to-whole-diameter ratio also differed between regions of the placenta in all groups, the most marked reduction being in the parachorial region and the least prominent in the parabasal zone; (3) no significant differences in the mean diameter ratio were found among the three sub-groups of the toxaemic pregnancies, i.e., the preeclampsia, essential hypertension and renal disease group; and (4) there was an inverse relationship between the lumen-to-whole-diameter ratios and the syncytial sprout counts in the toxaemic group.

Placental weight in diabetic pregnancies.

The placenta from 30 women with diabetes mellitus were examined and weighed at delivery. Nineteen of these were from women with overt and eleven from women with gestational diabetes. Eleven placentae from normal pregnancies served as controls. There was no difference between the mean +/- s.d. placental weight for the diabetic group and the control group (609 +/- 148 versus 591 +/- 93 g, NS). The mean placental weight ratios for the diabetic group and the control group were also similar (0.98 +/- 0.23 versus 0.89 +/- 0.15, NS). Moreover, there was no difference between the weights and weight ratios of placentae from women with overt (622 +/- 173 g, 1.02 +/- 0.27) and those with gestational diabetes (586 +/- 90 g, versus 0.90 +/- 0.13). Placental weights correlated with birthweights (r = 0.70, P less than 0.01) and with skinfold thickness measurements fo the infants (r = 0.40, P less than 0.05), but neither with gestational ages (r = 0.15, NS) nor with maternal glycosylated haemoglobin levels in the third trimester (r = 0.24, NS). Among the women with overt diabetes, placental weights were greater in those in White's class B and C than those in class D and R (689 +/- 143 versus 530 +/- 177 g; P less than 0.05). In general, placentae from well controlled diabetic patients were not heavier than those from normal pregnant women, although there was an increase in placental weight in White's class B and C, as compared with those in class D and R.

Ultrastructure of hepatic mitochondria in a child with hyperornithinemia, hyperammonemia, and homocitrullinuria.

Ultrastructural studies of hepatic tissue obtained at biopsy from a nine year old severely retarded boy with hyperornithinemia, hyperammonemia, and homocitrullinuria showed mitochondria of bizarre shapes and unusual internal features. Among the latter were tubules extending throughout the length of the large mitochondria that on cross section had a rosette-like arrangement; the presence of a periodic, approximately 300 A thick, sievelike membrane interposed between the tubules and the inner mitochondrial membrane; and "bulges" of mitochondrial matrix occasionally formed between these two membranes. Since to be metabolized ornithine must enter the mitochondria, the hyperornithinemia is regarded as a reflection of its inability to reach the mitochondrial interior. It is speculated that among other possible causes, the unusual sievelike membrane may be the barrier to ornithine's access to the mitochondrion.

The Canadian Atherosclerosis Society--history and present status.

Since its inception in 1983 the Canadian Atherosclerosis Society (CAS) has established itself firmly on the national and international scene as a forceful scientific voice. Its presence and activities have had their dominant expression at annual meetings held jointly with the Royal College of Physicians and Surgeons of Canada (RCPSC) and the Canadian Society for Clinical Investigation (CSCI) and in sponsoring other scientific and educational events, the most important of which was the Canadian Consensus Conference on Cholesterol (Ottawa, March 1988). It provided a forum for interaction between the scientific community, government, funding agencies, industry and the general public, and culminated in concrete recommendations for the populace of Canada. It also 'induced' a continuum in governmental and public concern for health with respect to atherosclerosis, and beyond it, the field of cardiovascular diseases. This dialogue continues. As a member (Constituent Society) of the International Atherosclerosis Society (IAS), the CAS has a voice in the international community, its policies and activities. The membership increase from 69 in 1983 to 175 in 1991 reflects steady growth of the CAS. The Society has been active in other areas (publications, awards for young investigators, and common educational endeavours with other groups) and will be host to the 1994 International Symposium on Atherosclerosis. Over a short period of only eight years, all of the above attests to sufficient progress (or achievement) for any scientific society. And yet, there remain quite a few areas not addressed as yet and some sad experiences (eg, that with the Long Term Planning Committee) that must be quickly remedied, if the Society is to keep pace with the everchanging emphasis in research that in the final analysis aims at improving the overall well-being and health of all Canadians. Inherent in the definition of history is the premise that accounts be provided of facts only. Historians who research their subjects derive these facts from studying the necessary accounts relating to these 'facts', using different and preferably controversial resources, so as to present the facts as objectively as possible. It is impossible, however, to fulfill all the above criteria for a historian who lived through every phase of 'life' of the subject of his or her account, because no matter how objective one wishes to remain (and bends backwards to achieve this) there will be always an element of a personal prism through which the historian lived the 'life' with his subject. For being human and thus unable to eliminate entirely that personal component, this writer asks humbly for the reader's understanding.

Ciliated cultured dermal fibroblasts in a patient with hyperornithinemia, hyperammonemia and homocitrullinuria (HHH) syndrome.

Hyperornithinemia, hyperammonemia and homocitrullinuria (HHH)-syndrome is a rare autosomal recessive disorder of the urea cycle, probably caused by a defect in ornithine transport across the hepatic inner mitochondrial membrane. Single rudimentary cilia were present in approximately ten percent of post-divisional or dividing fibroblasts cultured from the skin of a patient with the HHH-syndrome, whereas no such organelles were observed in dermal fibroblasts cultured from normal controls. Since single rudimentary ("primary," "oligo," "solitary") cilia have been observed in a variety of cells in animals and men but the stimuli for their formation and their significance remain controversial, a brief report on their presence in the as yet unreported condition (HHH-syndrome) was considered of interest; hopefully, it might contribute to the ultimate unravelling of some of the unresolved problems. It is of note that unlike the author's previous findings of these unusual organelles in cells affected by a pathological process (atherosclerosis), the rudimentary cilia were observed in the present instance in dividing or postdivisional cells. The implications of these (and other) observations must await further work.

Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH)-syndrome. Ultrastructural changes of mitochondria in cultured dermal fibroblasts of three patients.

Mitochondria of fibroblasts cultured from the skin obtained at biopsy from three patients with the hyperornithinemia-hyperammonemia-homocitrullinuria (HHH)-syndrome, one of the autosomal recessive, heritable urea cycle disorders, were studied with appropriate controls ultrastructurally. The patients were two severely retarded 10- and 12-year-old boys, and a 22-year-old sister of the former whose mental status was at the low normal range; she never had motor impairments or seizures. The mitochondria, similar in all three patients, were increased in number, very long, branching and/or "looping," and tortuous. "Spurs" or "buddings" extended from their lateral surfaces and the terminal segments were often bulbous. Other unusual configurations were also present. In addition, giant forms with large diameter contained innumerable closely-packed and parallel cristae which traversed the entire width of these mitochondria; at times they assumed a "whirled" pattern. The mitochondrial matrix was usually of high electron density. These changes were not a feature of fibroblastic mitochondria of controls. Several changes resembled those of hepatic mitochondria in this disorder. All features are interpreted as an attempt at expanding the mitochondrial volume (via structural substratum) to compensate for the metabolic incompetence of these organelles (a block in transmembranous transfer of ornithine from hyaloplasm into mitochondria for conversion to citrulline).

Ultrastructure and peroxidase of leucocytes in five patients with juvenile form of ceroid lipofuscinoses.

Peripheral leucocytes obtained from five patients with clinical histories and funduscopic findings typical of the juvenile form of the so-called neuronal ceroid lipofuscinosis (NCLF) (synonym: Spielmeyer-Vogt disease) were assayed for peroxidase activity and examined by electron microscopy. The peroxidase levels were considerably lower in three but normal in two patients. Ultrastructurally, the lymphocytes of all five patients showed the presence of tubulo-membranous cytosomes many displaying the fingerprint images at present regarded as being typical for the NCLF. The possible implications of the discrepancy between the morphological observations and the enzymatic findings are discussed.