Identification of a danger-associated peptide from apolipoprotein B100 (ApoBDS-1) that triggers innate proatherogenic responses

BACKGROUND

Subendothelial deposited low-density lipoprotein particles are a known inflammatory factor in atherosclerosis. However, the causal components derived from low-density lipoprotein are still poorly defined. Apolipoprotein B100 (ApoB100) is the unexchangeable protein component of low-density lipoprotein, and the progression of atherosclerosis is associated with immune responses to ApoB100-derived peptides. In this study, we analyzed the proinflammatory activity of ApoB100 peptides in atherosclerosis.

METHODS AND RESULTS

By screening a peptide library of ApoB100, we identified a distinct native peptide referred to as ApoB100 danger-associated signal 1 (ApoBDS-1), which shows sequence-specific bioactivity in stimulation of interleukin-8, CCL2, and interleukin-6. ApoBDS-1 activates mitogen-activated protein kinase and calcium signaling, thereby effecting the expression of interleukin-8 in innate immune cells. Ex vivo stimulation of carotid plaques with ApoBDS-1 enhances interleukin-8 and prostaglandin E₂ release. Furthermore, we demonstrated that ApoBDS-1-positive peptide fragments are present in atherosclerotic lesions using immunoassays and that low-molecular-weight fractions isolated from plaque show ApoBDS-1 activity inducing interleukin-8 production.

CONCLUSIONS

Our data show that ApoBDS-1 is a previously unrecognized peptide with robust proinflammatory activity, contributing to the disease-promoting effects of low-density lipoprotein in the pathogenesis of atherosclerosis.

Rip2 deficiency leads to increased atherosclerosis despite decreased inflammation

RATIONALE

The innate immune system and in particular the pattern-recognition receptors Toll-like receptors have recently been linked to atherosclerosis. Consequently, inhibition of various signaling molecules downstream of the Toll-like receptors has been tested as a strategy to prevent progression of atherosclerosis. Receptor-interacting protein 2 (Rip2) is a serine/threonine kinase that is involved in multiple nuclear factor-κB (NFκB) activation pathways, including Toll-like receptors, and is therefore an interesting potential target for pharmaceutical intervention.

OBJECTIVE

We hypothesized that inhibition of Rip2 would protect against development of atherosclerosis.

METHODS AND RESULTS

Surprisingly, and contrary to our hypothesis, we found that mice transplanted with Rip2(-/-) bone marrow displayed markedly increased atherosclerotic lesions despite impaired local and systemic inflammation. Moreover, lipid uptake was increased whereas immune signaling was reduced in Rip2(-/-) macrophages. Further analysis in Rip2(-/-) macrophages showed that the lipid accumulation was scavenger-receptor independent and mediated by Toll-like receptor 4 (TLR4)-dependent lipid uptake.

CONCLUSIONS

Our data show that lipid accumulation and inflammation are dissociated in the vessel wall in mice with Rip2(-/-) macrophages. These results for the first time identify Rip2 as a key regulator of cellular lipid metabolism and cardiovascular disease.

Nuclear factor {kappa}B-mediated transactivation of telomerase prevents intimal smooth muscle cell from replicative senescence during vascular repair

OBJECTIVE

To gain insights into mechanisms by which intimal hyperplasia interferes with the repair process by investigating expression and function of the catalytic telomerase reverse transcriptase (TERT) subunit after vascular injury.

METHODS AND RESULTS

Functional telomerase is essential to the replicative longevity of vascular cells. We found that TERT was de novo activated in the intima of injured arteries, involving activation of the nuclear factor κB pathway. Stimulation of the isolated intimal smooth muscle cell (SMC) by basic fibroblast growth factor or tumor necrosis factor α resulted in increased TERT activity. This depends on the activation of c-Myc signaling because mutation of the E-box in the promoter or overexpression of mitotic arrest deficient 1 (MAD1), a c-Myc competitor, abrogated the transcriptional activity. Inhibition of nuclear factor κB in both intimal SMCs and the injured artery attenuated TERT transcriptional activity through reduction of c-Myc expression. Pharmacological blockade of TERT led to SMC senescence. Finally, depletion of telomerase function in mice resulted in severe intimal SMC senescence after vascular injury.

CONCLUSIONS

These results support a model in which vascular injury induces de novo expression of TERT in intimal SMCs via activation of nuclear factor κB and upregulation of c-Myc. The resumed TERT activity is critical for intimal hyperplasia.

T cell-mediated inflammation in adipose tissue does not cause insulin resistance in hyperlipidemic mice

Obesity is associated with chronic inflammation in adipose tissue. Proinflammatory cytokines including tumor necrosis factor-alpha and interleukin-6 secreted by adipose tissue during the metabolic syndrome are proposed to cause local and general insulin resistance and promote development of type 2 diabetes. We have used a compound mutant mouse, Apoe(-/-)xCD4dnTGFbR, with dysregulation of T-cell activation, excessive production of proinflammatory cytokines, hyperlipidemia, and atherosclerosis, to dissect the role of inflammation in adipose tissue metabolism. These mice are lean, which avoids confounding effects of concomitant obesity. Expression and secretion of a set of proinflammatory factors including tumor necrosis factor-alpha, interferon-gamma, and monocyte chemoattractant protein-1 was increased in adipose tissue of Apoe(-/-)xCD4dnTGFbR mice, as was the enzyme 11beta-hydroxysteroid dehydrogenase type 1, which converts cortisone to bioactive cortisol. Interleukin-6, which has an inhibitory glucocorticoid response element in its promoter, was not upregulated. In spite of intense local inflammation, insulin sensitivity was not impaired in adipose tissue of Apoe(-/-)xCD4dnTGFbR mice unless exogenous interleukin-6 was administered. In conclusion, T-cell activation causes inflammation in adipose tissue but does not lead to insulin resistance in this tissue in the absence of interleukin-6.

Effects of social isolation and environmental enrichment on atherosclerosis in ApoE-/- mice

Social support and a stimulating environment have been suggested to reduce stress reactions and cardiovascular risk. The aim of this study was to assess the role of environmental enrichment and social interaction for development of atherosclerosis in atherosclerosis prone mice. Male ApoE-/- mice were divided into four groups and followed during 20 weeks: (i) enriched environment (E, n=12), (ii) deprived environment (ED, n=12), (iii) enriched environment with exercise (E-Ex, n=12) and (iv) socially deprived by individual housing (SD, n=10). Plasma lipid and cytokine concentrations were measured. Atherosclerosis was quantified in cross-sections of innominate artery and en face in thoracic aorta. Plaque area was significantly increased in SD mice in the innominate artery (P<0.05 vs. all other groups), but not in the thoracic aorta. Plasma lipids were increased in SD mice (P<0.001 vs. all for total cholesterol, P<0.05 vs. E and P<0.01 vs. ED for triglycerides). Plasma concentration of granulocyte-colony stimulating factor (G-CSF) was decreased in SD mice compared to E mice (P<0.05). Thus, social isolation increased atherosclerosis and plasma lipids in ApoE-/- mice. Reduction in plasma G-CSF levels may hamper endothelial regeneration in the atherosclerotic process. While environmental enrichment did not affect atherosclerosis, social isolation accelerated atherosclerosis.

Hyperinsulinemic rats are normotensive but sensitized to angiotensin II

The effect of insulin on blood pressure (BP) is debated, and an involvement of an activated renin-angiotensin aldosterone system (RAAS) has been suggested. We studied the effect of chronic insulin infusion on telemetry BP and assessed sympathetic activity and dependence of the RAAS. Female Sprague-Dawley rats received insulin (2 units/day, INS group, n = 12) or insulin combined with losartan (30 mg·kg−1·day−1, INS+LOS group, n = 10), the angiotensin II receptor antagonist, for 6 wk. Losartan-treated (LOS group, n = 10) and untreated rats served as controls ( n = 11). We used telemetry to measure BP and heart rate (HR), and acute ganglion blockade and air-jet stress to investigate possible control of BP by the sympathetic nervous system. In addition, we used myograph technique to study vascular function ex vivo. The INS and INS+LOS groups developed euglycemic hyperinsulinemia. Insulin did not affect BP but increased HR (27 beats/min on average). Ganglion blockade reduced mean arterial pressure (MAP) similarly in all groups. Air-jet stress did not increase sympathetic reactivity but rather revealed possible blunting of the stress response in hyperinsulinemia. Chronic losartan markedly reduced 24-h-MAP in the INS+LOS group (−38 ± 1 mmHg P < 0.001) compared with the LOS group (−18 ± 1 mmHg, P ≤ 0.05). While insulin did not affect vascular function per se, losartan improved endothelial function in the aorta of insulin-treated rats. Our results raise doubt regarding the role of hyperinsulinemia in hypertension. Moreover, we found no evidence that insulin affects sympathetic nervous system activity. However, chronic losartan treatment revealed an important interaction between insulin and RAAS in BP control.

Angiotensin type 2 receptor is expressed in human atherosclerotic lesions

Objective. Expression of the angiotensin type 2 receptor (AT2-receptor) occurs in many animal models of atherosclerosis. However, its expression in human plaques and its functional role remains undetermined.This study examined AT2-receptor expression in human atherosclerotic plaque and also explored its potentially important functional role in atherosclerosis.

Material and methods. We analysed carotid atherosclerotic plaques obtained from 14 Caucasian patients who had previously carotid artery stenosis. Half of all subjects undergone endarterectomy for symptomatic carotid artery stenosis. Half of all subjects received treatment with an angiotensin receptor blocker (ARB) (n=7); the remaining subjects received no intervention in the renin-angiotensin system (n=7). Immunohistochemistry measured tissue expression of smooth muscle cells (α-actin), macrophages (CD68 antibody), collagen (picro-sirius), and AT2-receptor (AT2-receptor antibody).

Results. AT2-receptor expression occurred consistently in all specimens. Although cellular localisation varied, AT2-receptor expression levels correlated with macrophage levels (p<0.01). Compared to conventional treatment, ongoing ARB treatment affected neither AT2-receptor levels nor plaque composition.

Conclusions. AT2-receptor is expressed in human atherosclerotic plaque. Furthermore, we detected no functionally important role of AT2-receptor expression and found no evidence that ARB treatment regulates AT2-receptor expression.

Blood pressure is the major driving force for plaque formation in aortic-constricted ApoE−/− mice

OBJECTIVE

Using an aortic constriction model in mice, we studied whether the increase in pressure or the activation of the renin-angiotensin system (RAS) and its main receptors is the main driving force for plaque progression.

METHODS

Male ApoE mice underwent sham surgery or placement of a suprarenal silver clip around the aorta (AoC). Half the group was treated with the selective AT1 receptor antagonist losartan (30 mg/kg per day) for 4 weeks.

RESULTS

Anesthetized mean arterial pressure (MAP) was increased in AoC mice compared to sham (106 +/- 3 versus 90 +/- 1 mmHg, P < 0.001). Losartan reduced MAP in sham mice (78 +/- 2 mmHg, P < 0.01) but not in AoC (AoC losartan 104 +/- 2 mmHg). Plasma renin concentration (PRC) was increased in AoC mice compared to sham [1.6 +/- 0.3 versus 0.8 +/- 0.2 milliGoldblatt units (mGU)/ml, P < 0.001]. Losartan treatment augmented this difference (18.7 +/- 3.7 versus 4.6 +/- 1.7 mGU/ml, P < 0.01). AT2 receptor mRNA expression was increased 5.8-fold by aortic constriction in thoracic aorta (P < 0.05) and the major site for expression of the AT2 receptor protein was within the plaques. The plaque area was increased in AoC mice compared to sham (0.61 +/- 0.09 versus 0.07 +/- 0.01%, P < 0.001); however, losartan did not alter plaque area.

CONCLUSIONS

Our data do not support a role for the AT1 receptor in the progression of atherosclerosis in this model, since blockade with losartan did not alter plaque distribution. Furthermore, we found no support for the counteraction of atherogenesis by increased activity of the RAS acting on the AT2 receptor. Our data suggest that increased pressure is the main driving force for atherosclerosis in this model.

Endothelial dysfunction in growth hormone transgenic mice

Acromegaly [overproduction of GH (growth hormone)] is associated with cardiovascular disease. Transgenic mice overexpressing bGH (bovine GH) develop hypertension and hypercholesterolaemia and could be a model for cardiovascular disease in acromegaly. The aims of the present study were to investigate the effects of excess GH on vascular function and to test whether oxidative stress affects endothelial function in bGH transgenic mice. We studied the ACh (acetylcholine)-induced relaxation response in aortic and carotid rings of young (9–11 weeks) and aged (22–24 weeks) female bGH transgenic mice and littermate control mice, without and with the addition of a free radical scavenger {MnTBAP [Mn(III)tetrakis(4-benzoic acid)porphyrin chloride]}. We also measured mRNA levels of eNOS (endothelial nitric oxide synthase) and EC-SOD (extracellular superoxide dismutase). Intracellular superoxide anion production in the vascular wall was estimated using a dihydroethidium probe. Carotid arteries from bGH transgenic mice had an impaired ACh-induced relaxation response (young, 46±7% compared with 69±8%; aged, 52±5% compared with 80±3%; P<0.05), whereas endothelial function in aorta was intact in young but impaired in aged bGH transgenic mice. Endothelial dysfunction was corrected by addition of MnTBAP in carotid arteries from young mice and in aortas from aged mice; however, MnTBAP did not correct endothelial dysfunction in carotid arteries from aged bGH transgenic mice. There was no difference in intracellular superoxide anion production between bGH transgenic mice and control mice, whereas mRNA expression of EC-SOD and eNOS was increased in aortas from young bGH transgenic mice compared with control mice (P<0.05). We interpret these data to suggest that bGH overexpression is associated with a time- and vessel-specific deterioration in endothelial function, initially caused by increased oxidative stress and later by other alterations in vascular function.

Angiotensin II, type 2 receptor is not involved in the angiotensin II-mediated pro-atherogenic process in ApoE-/- mice

OBJECTIVE

Angiotensin II (Ang II) accelerates atherogenesis in ApoE mice via the angiotensin II, type 1 receptor (AT1) while the type 2 receptor (AT2) is suggested to counteract atherogenesis. To confirm and further explore this possibility, we studied the effect of AT2 receptor antagonism on Ang II-accelerated atherosclerosis.

METHODS

ApoE mice were fed a standard or high cholesterol diet (1.25%) for 4 weeks. Mice on each diet were treated with either Ang II (0.5 microg/kg per min) or Ang II in combination with PD123319 (3 mg/kg per day). Plaque distribution was assessed by en face quantification of the thoracic aorta and in cross-sections of the aortic root. Mean arterial pressure (MAP) was measured. AT1 and AT2 receptor expression were analysed using real-time polymerase chain reaction (PCR) and the localization of the AT2 receptor protein confirmed with immunohistochemistry.

RESULTS

Ang II infusion increased MAP only in mice on a standard diet (P < 0.001). Regardless of diet, Ang II-infused mice had 22-30 times increased plaque area in the thoracic aorta (P < 0.001 for both). Ang II had no effect on plaque in the aortic root. Plaque area was not affected by PD123319. AT2 receptor was heavily expressed in the plaques and increased six- to ninefold by a high cholesterol diet and Ang II infusion (P < 0.01).

CONCLUSION

Ang II increases the extent of atherosclerosis in ApoE mice. Despite up-regulation of the AT2 receptor, we found no support for an effect of the AT2 receptor on atherogenesis in this model.

Haemodynamically significant plaque formation and regional endothelial dysfunction in cholesterol-fed ApoE−/− mice

Flow-mediated vasodilation is suggested as one of the mechanisms involved in arterial expansive remodelling, which is thought to be a defence mechanism in atherogenesis. In the present study, we tested the hypothesis that lumen obstructive plaque formation is associated with failure of NO (nitric oxide)-dependent vasodilation in conduit vessels. Cardiac function and aortic root flow velocities were assessed using high-resolution echocardiography and two-dimensional-guided pulsed Doppler in ApoE−/− (apolipoprotein E-deficient) mice fed a standard or high-cholesterol diet. Endothelial function in the proximal and mid-descending aortic regions was studied using a myograph technique. Flow velocity at the aortic root of cholesterol-fed ApoE−/− mice was significantly increased as a result of lumen narrowing, detected via histological analysis. NO-dependent vasodilatory responses were selectively impaired in the atherosclerosis-prone vascular regions in cholesterol-fed ApoE−/− mice. In conclusion, consumption of a high-cholesterol diet results in lumen obstructive plaque formation in ApoE−/− mice, which significantly alters aortic root haemodynamics. This phenomenon is associated with impaired NO-dependent vasodilation in vessel segments known to be prone to atherosclerosis.

Gene expression profile and aortic vessel distensibility in voluntarily exercised spontaneously hypertensive rats: potential role of heat shock proteins

Physical exercise is considered to be beneficial for cardiovascular health. Nevertheless, the underlying specific molecular mechanisms still remain unexplored. In this study, we aimed to investigate the effects of voluntary exercise on vascular mechanical properties and gene regulation patterns in spontaneously hypertensive rats. By using ultrasound biomicroscopy in an ex vivo perfusion chamber, we studied the distensibility of the thoracic aorta. Furthermore, exercise-induced gene regulation was studied in aortae, using microarray analysis and validated with real-time PCR. We found that distensibility was significantly improved in aortas from exercising compared with control rats (P < 0.0001). Exercising rats demonstrated a striking pattern of coordinated downregulation of genes belonging to the heat shock protein family. In conclusion, voluntary exercise leads to improved vessel wall distensibility and reduced gene expression of heat shock protein 60 and 70, which may indicate decreased oxidative stress in the aortic vascular wall.

The glycosylation of rat intestinal Muc2 mucin varies between rat strains and the small and large intestine. A study of O-linked oligosaccharides by a mass spectrometric approach

The large glycosylated domains obtained from the rat intestinal mucin Muc2 were isolated from the large and small intestine of the inbred rat strains GOT-W and GOT-BW. The expression of the rat Muc2 in the large intestine was confirmed immunochemically and by Northern blotting. Released oligosaccharides were structurally characterized by gas chromatography-mass spectrometry (neutral and sialylated species) or by tandem mass spectrometry (sulfated species), and a total of 63 structures was assigned. The large intestinal oligosaccharides were found to be identical between the strains, while the small intestinal glycosylation differed. Until now, detailed structural analysis of oligosaccharides isolated from a single mucin core or mucin domain with different origin have not been performed, and the information of different mucin glycoforms has been limited to immunochemistry. Blood group A-determinants (GalNAcalpha1-3(Fucalpha1-2)Galbeta1-, and structures related to the blood group Sda/Cad-related epitope NeuAc/NeuGcalpha1-3(GalNAcbeta1-4)Galbeta1-, were found in GOT-BW small intestine, and also in both large intestines. Blood group H-determinants and NeuAc/NeuGcalpha1-3Galbeta1- were found in all samples. Core 1 (Galbeta1-3GalNAcalpha1-), core 2 (Galbeta1-3(GlcNAcbeta1-6)GalNAcalpha1-), core 3 (GlcNAcbeta1-3GalNAcalpha1-), and core 4 (GlcNAcbeta1-3(GlcNAcbeta1-6)GalNAcalpha1- were also found in all the samples. The large intestine were enriched in sulfated oligosaccharides and the small intestine contained higher amounts of sialylated species. Sulfation were found exclusively on C-6 of GlcNAc.

Molecular characterization of the large heavily glycosylated domain glycopeptide from the rat small intestinal Muc2 mucin

The largest high-glycosylated domain, glycopeptide A, of the "insoluble' mucin complex of the rat small intestine has earlier been purified and characterized (Carlstedt et al., 1993, J Biol Chem 268: 18771-81). A rabbit antiserum raised against deglycosylated glycopeptide A was used to clone part of a mucin showing homology to the human MUC2 mucin (Hansson et al., 1994, Biochem Biophys Res Commun 198. 181-90). This serum specifically stained goblet cells (paranuclear) in the mouse small intestine. The size of the coding sequence of glycopeptide A was estimated by using reversed transcriptase PCR of mRNA from an inbred rat strain (GOT-W) using primers in the unique central and C-terminal parts of the proposed rat Muc2 sequences. The PCR and Southern blot of the PCR products showed a fragment of about 5.5 kb corresponding to about 1700 amino acids when the known Cys-rich sequences used for the primers were subtracted. This is slightly larger than the size estimated earlier by biochemical studies. The mRNA encoding the rat Muc2 was slightly smaller than the mRNA encoding the human MUC2 in a colorectal cell line. Although the size of glycopeptide A estimated from biochemical results and by PCR is not identical, the results obtained here further support that the "insoluble' mucin of the rat small intestine is encoded by the Muc2 gene. Most of the oligosaccharides in glycopeptide A were either neutral (40%) or sialylated (40%). The remaining ones were sulfated with the sulfate group attached to C-6 of N-acetylglucosamine linked to C-6 of the N-acetylgalactosaminitol as revealed by tandem mass spectrometry of the perdeuteroacetylated oligosaccharides. Eighteen oligosaccharides were found of which fourteen were characterized and found to be mostly novel. Our findings thus expand the current knowledge of the core peptide of the rat intestinal goblet cell mucin and provide a relatively complete picture of the glycosylation of a defined mucin domain.

Adenoviruses isolated in the Stockholm area during 1987-1992: restriction endonuclease analysis and molecular epidemiology

Adenoviruses recovered from the northern Stockholm area during 1987-1992 have been subjected to restriction endonuclease analysis. Adenoviruses of all subgenera (A-F) were represented and a considerable degree of serotype variation was seen, e.g. the rarely encountered subgenus A viruses were frequently isolated in the present study. Of 16 subgenus A isolates, Ad31 predominated with 12 strains which were equally distributed into the DNA-variants D2 and D7. Analysis of 38 Ad3 isolates revealed four DNA-variants: D1, D3, D10, and "Sto1". The ten Ad7 isolates belonged all to the DNA-variant D5 of Ad7. Of 27 Ad1 strains, 11 belonged to D10, followed by the DNA-variants D4 and D7 with four strains each. Among Ad2 isolates, D2 or D2-like strains prevailed (23/28). Of six Ad5 strains, three belonged to the DNA-variant D2. The most notable subgenus D event was a nosocomial outbreak of keratokonjunctivitis due ot Ad19a. In addition, a collection of heterogenous subgenus D strains was detected, most of which untypable by RE-analysis. Among the six Ad4 isolates of subgenus E, both genomic clusters (p and a, respectively) of Ad4 were recognized. Concerning the clinical important subgenus F adenoviruses, only two strains of Ad40 were detected as compared to 12 strains of Ad41, all of which ascribed to the DNA-variant D12 of Ad41.

Characterization of two divergent adenovirus 31 strains

Two divergent strains of adenovirus type 31 were analyzed by neutralization test and restriction endonuclease (RE) patterns in an effort to find the basis for their genetic variability. One strain, isolated from the throat of a child in Maryland during an upper respiratory illness in 1968, was partially neutralized by Ad 31 antisera (to 16-fold lower than homologous titer) while its own antiserum fully neutralized prototype Ad 31 virus, but shared only 9% of comigrating RE fragments with Ad 31 prototype (vs. 30% with Ad 18 prototype); however, PCR tests specific for the inverted terminal repeat (ITR) sequence of Ads 12 and 18 were negative. The other strain, recovered from a stool sample from an infant with diarrhea in Georgia in 1979, was inhibited by Ad 31 antiserum to within 4-fold homologous titer, but shared only 15% of comigrating fragments with Ad 31 prototype (vs. 91% with Ad 18 prototype); ITR-specific PCR tests with this virus were positive for Ad 12/Ad 18. These data suggest that both strains are from separate evolutionary lines of Ad 31 unrelated to all other isolates studied to date by RE analysis, and that the partial neutralization by prototype Ad 31 antisera might represent small mutations in the hexon gene.

Molecular epidemiology of adenoviruses isolated in Iceland during 1988-1990

All human adenoviruses isolated in Iceland during 1988-1990 have been subjected to restriction endonuclease analysis. Of 55 isolates altogether, subgenus C (Ad1, Ad2, and Ad5) predominated with 42 isolates followed by subgenus B (Ad3 and Ad7) with 12. Analysis of the 9 Ad1 isolates revealed 6 DNA-variants. Among these the established DNA-variants D4, D7, and D10 were recognized. The remaining 3 DNA-variants were primarily found in Iceland. Among the 22 Ad2 isolates, 7 DNA-variants could be distinguished. D2 predominated with 15 isolates whereas the prototype was isolated only once. The novel 5 DNA-variants of Ad2 were all closely related to D2. Analysis of the 11 Ad5 isolates revealed 6 DNA-variants, 2 of which (D2 and D5) were already established. Ice2 and D3 were the most common occurring DNA-variants of Ad5. Ad5 showed the highest degree of genomic variability within subgenus C, both in terms of the low degree of pair-wise comigration of restriction fragments and the number of principal variants of RE-patterns. Analysis of the 9 Ad3 isolates revealed 3 DNA-variants: D3, D10, and Ice1 (a novel DNA-variant that resembles D10). The DNA-variants D3 and D10 were each represented by 4 isolates. The three Ad7 isolates belonged all to the DNA-variant D5.

Restriction endonuclease patterns of adenovirus type 12 and 18

Restriction endonuclease analysis using 10 restriction enzymes was performed on six and three wild isolates of adenovirus (Ad) type 12 and 18, respectively. Among the Ad12 strains, five DNA variants could be identified. The degree of pairwise comigration of restriction fragments suggests a high degree of genomic diversity within Ad12. The wild isolates of Ad18, on the other hand, displayed a low degree of genetic variability and comprised one DNA variant closely related to the prototype strain. The BglII, BstEII, and HindIII restriction endonuclease patterns of Ad18 were inconsistent with those originally presented. Identical RE-patterns among Ad18 prototype strains (DC) obtained from four different sources, including directly from the American Type Culture Collection, verify that the genuine Ad18 prototype was used in the present study. Using the revised restriction patterns of BglII, BstEII, and HindIII, a proper identification of Ad18 will be facilitated.

Intrauterine fetal death due to echovirus 11

In a case of intrauterine fetal death in the 29th week of gestation, echovirus 11 could be isolated from the umbilical cord of the fetus. The mother had no apparent signs of infection but serological evidence of current echovirus 11 infection. Enterovirus PCR performed on paraffin-embedded specimens of various tissues (myocardium, lung, liver and placenta) from the fetus yielded positive results in all cases. These findings, together with supporting serological and epidemiological findings--e.g. proven echovirus 11 infection 3 weeks before in the 18-month-old son of the woman--constituted strong evidence that echovirus 11 infection was responsible for the fetal death.

Genome analysis of adenovirus type 31 strains from immunocompromised and immunocompetent patients

Adenovirus type 31 (Ad31) was isolated from 15 immunocompromised patients in 12 of whom seroconversion was also recorded. Ad31 infection has a substantial clinical relevance since 8 of 10 with lower respiratory tract infection and 4 of 4 with hepatitis died. Therefore, Ad31 isolates from immunocompetent and immunodeficient hosts were compared by restriction endonuclease analysis. Nine genome types were identified among the 79 Ad31 isolates. Pairwise comparison of comigrating restriction fragments indicated that the genome types could be divided into three genomic clusters. Several Ad31 genome types were isolated from immunocompromised patients, but no highly virulent genome type could be found. A genome type was identified in a child with severe combined immunodeficiency who originally was infected with another genome type. This observation is suggested to have evolutionary implications.

Characterization of two genome types of adenovirus type 31 isolated in Stockholm during 1987

The authors isolated during 1987 seven adenovirus type 31 (Ad31) within a 9-month period. The isolates were obtained from urine, throat, and feces, implying a systemic spread of the infection. Most patients displayed gastrointestinal symptoms, but some had respiratory symptoms and fever. All of the strains differed by restriction endonuclease analysis from the prototype strain (1315) by an additional Bgl II restriction site. Ad31 isolates 1-6 could be divided into two groups by the enzymes Bam HI, Msp I, and Xho I. Each enzyme gave rise to the same group distribution: isolates 1-3 and 4-6, respectively. Digestion with Bst EII, Hind III, Kpn I, and Sma I resulted in identical patterns for isolates 1-6. Isolate 7, however, demonstrated a DNA deletion of approximately 0.8 kbp, but it was otherwise identical to isolates 4-6. In conclusion, two separate genome types of Ad31 were isolated, one of which included a DNA deletion mutant. The increased isolation rate may reflect an epidemiological situation, as the same isolation procedure had been used both before and after this period.

Optimization of a fluid bed spray coating process using reduced factorial design

A sequential approach to the optimization of a fluid bed coating process of pellets for controlled release using organic solvents and ethylcellulose has been applied using reduced factorial experiments. The optimization was started by applying a 2(4-1) experiment then, based on the results from that study, further experiments were carried out where only the variables which had the most significant effect on the film yield were used. Finally, a 2(3-1) experiment was performed. A relationship was found between the film yield and degree of agglomeration, indicating a limiting value of the film yield (75 per cent) below which only little agglomeration takes place. Above this value, the degree of agglomeration increases dramatically. The limit value was found to change only to a minor extent as a function of experimental conditions.

Investigation of the film formation of magnesium stearate by applying a flow-through dissolution technique

The film formation of magnesium stearate on the surface of acetylsalicylic acid was investigated by applying a flow-through dissolution technique. The effect of mixing time, lubricant surface area, and the addition of colloidal silica was studied. The film formation increased by increasing mixing time. The final level reached was independent of the specific surface area of the lubricants, but granular magnesium stearate gave a lower surface coverage than the powdered lubricants. The lubricating effect was independent of the mixing time and specific surface area of the lubricants. Colloidal silica was found to interact primarily with the free fraction of magnesium stearate.