Extracellular matrix remodeling in the vascular wall

The extracellular matrix provides a structural framework essential for the functional properties of vessel walls. The three dimensional organization of the extracellular matrix molecules--elastin, collagens, proteoglycans and structural glycoproteins--synthesized during fetal development--is optimal for these functions. Early in life, the vessel wall is subjected to injury: lipid deposition, hypoxia, enzyme secretion and reactive oxygen species production during inflammatory processes, and the extracellular matrix molecules are hydrolyzed by proteases--matrix metalloproteinases, leukocyte elastase, etc. In uninjured arteries and veins, some proteases are constitutively expressed, but through the control of their activation and/or their inhibition by inhibitors, these proteases have a very low activity. During the occurrence of vascular pathologies--atherosclerosis, hypertension, varicosis, restenosis, etc.--the balance between proteases and their inhibitors is temporally destroyed through the induction of matrix metalloproteinase gene expression or the secretion of enzymes by inflammatory cells. Smooth muscle cells, the most numerous cells in vascular walls, have a high ability to respond to injury through their ability to synthesize extracellular matrix molecules and protease inhibitors. However, the three dimensional organization of the newly synthesized extracellular matrix is never functionally optimal. In some other pathologies--aneurysm--the injury overcomes the responsive capacity of smooth muscle cells and the quantity of extracellular matrix decreases. In conclusion, care should be taken to maintain the vascular extracellular matrix reserve and any therapeutic manipulation of the protease/inhibitor balance must be perfectly controlled, because an accumulation of abnormal extracellular matrix may have unforeseen adverse effects.

The natural history of incidental renal artery stenosis in patients with aortoiliac vascular disease

PURPOSE

To examine the association between incidentally discovered renal artery stenosis and deterioration of renal function as determined by the change in serum creatinine concentration over time.

SUBJECTS AND METHODS

We performed a retrospective review of consecutive patients who underwent aortography for aortoiliac vascular disease. Angiograms were reviewed for renal artery stenosis, defined as a narrowing of at least 20% compared with adjacent normal renal artery. For patients with at least 180 days of subsequent follow-up, the change in serum creatinine concentration per year was compared in patients who had or did not have renal artery stenosis.

RESULTS

Of the 201 patients, 96 (48%) had some degree of renal artery stenosis in one or both renal arteries, including 53 (26%) who had at least one stenosis > or= 50% and 40 (20%) who had bilateral stenoses. The only clinical predictor of renal artery stenosis was a history of coronary artery disease (odds ratio = 2.0, 95% confidence interval: 1.2 to 3.8, P = 0.001). Among the 174 patients with > or =180 days of follow-up, there was no statistically significant difference (P = 0.88) in the mean change in serum creatinine concentration per year in the 78 patients with renal artery stenosis (0.06+/-0.33 mg/dL per year) as compared with the 96 patients without renal artery stenosis (0.06+/-0.22 mg/dL per year). Grouping the patients by the maximal percentage of stenosis did not reveal any difference in the mean changes in serum creatinine concentration per year.

CONCLUSIONS

Although renal artery stenosis is a common incidental finding in patients with atherosclerotic vascular disease, it is an uncommon cause of progressive renal disease.

Renal transplant dysfunction due to severe aorto-iliac atherosclerosis in the presence of patent renal transplant artery

We report a case of progressive deterioration in renal function and decreased renal graft perfusion induced by extensive aorto-iliac atherosclerotic lesions proximal to a patent renal graft artery. Significant improvement in kidney graft function followed left axillo-femoral bypass graft surgery, which to the best of our knowledge, has never been performed previously for permanent maintenance of renal transplant perfusion.

Cold agglutinin disease in a patient with uterine sarcoma

Cold agglutinin disease is a rare clinical scenario. It is usually associated with infection, drug reaction, and hematologic malignancy, such as non-Hodgkin lymphoma or lymphocytic leukemia. We report a case of cold agglutinin disease in a patient with solid-tumor uterine sarcoma. Immunological dysregulation has been proposed as the pathogenesis for this disease. We also summarize recently reported cases of cold agglutinin disease, the underlying conditions, and advances in the management of cold agglutinin disease.

Cigarette smoking in multicultural, urban high school students

PURPOSE

To profile patterns of cigarette use among a multiethnic population of high school students, and identify important factors associated with cigarette use by ethnicity, in order to plan effective health promotion strategies.

METHODS

This cross-sectional study involved the completion of a lifestyle questionnaire by 1236 Grade 9-13 students (86% response rate) from 62 randomly selected classrooms in three urban high schools in Toronto. Chi-square analysis of the association between tobacco use and other variables took account of the clustered sample using CSAMPLE in Epi Info.

RESULTS

The students self-identified their ethnicity as follows: 388 Canadian, 269 European, 171 East Indian, 137 Asian, 76 West Indian, and 194 "other." Students who identified themselves as Canadians were significantly more likely to be current smokers (29%) than students reporting other ethnicities (13%). There was no apparent increase in smoking rates for immigrants after 2 or more years in Canada. Current drinking, sexual activity, and especially friends smoking was most strongly associated with current smoking for most ethnic groups, although the relative importance of these variables was not identical for all groups.

CONCLUSIONS

Prevention programs may benefit from a focus on the influence of peer smoking and on the grouping together of lifestyle factors associated with smoking for students in all ethnic groups in this multicultural city.

[Home-making responsibilities and health of working women]

OBJECTIVE

To analyze the relationship between the distribution of home-making responsibilities and perceived mental and physical health in working women.

MATERIAL AND METHODS

A cross-sectional study was conducted between September 1994 and October 1995, in Caracas, Venezuela. A total of 260 university teachers were surveyed on home-making management and activities. Statistical analysis consisted of central tendency measures, analysis of variance and hierarchical multiple regression.

RESULTS

Considering the distribution of home-making responsibilities, it was found that women participated more in home-making management and planning and that they received support from their partner in those tasks related to home-making. Those women who perceived higher overload in home-tasks reported also higher levels of anxiety, depression and a lower self-esteem.

CONCLUSIONS

These results indicate the negative effects of household labor on mental health in working women.

Escherichia coli O157:H7 outbreak associated with an improperly chlorinated swimming pool

A cluster of gastrointestinal illnesses, including one case of hemolytic-uremic syndrome and one culture-confirmed Escherichia coli O157:H7 infection, followed a trailer park pool party. We interviewed a cohort of party attendees and park residents. A primary case was defined as the first gastrointestinal illness within a household between 5 July and 20 July in which the titer of IgG antibody to E. coli O157 (if determined) was elevated. Of 51 party attendees and trailer park residents, 18 developed a gastrointestinal illness, including 10 who met the definition of a primary case. Swimming in the pool significantly increased the risk of primary illness (relative risk = 6.3; 95% confidence interval = 1.8-18.9). No other exposure was significantly associated with primary illness, after pool exposure was controlled for. The implicated pool had little to no chlorine added during the period of 4-10 July. This outbreak provides new evidence of the importance of proper pool maintenance in controlling the spread of E. coli O157:H7.

Defective expression of the SHP-1 phosphatase in polycythemia vera

The SHP-1 phosphatase associates with the receptors for erythropoietin, stem cell factor, and interleukin-3, and negatively regulates the mitogenic signals generated during engagement by their respective ligands. The erythroid progenitors of patients with polycythemia vera are hypersensitive to the mitogenic effects of these growth factors despite the fact that the numbers and binding affinities for their receptors are not increased. To determine whether post-receptor signaling defects may account for growth factor-hypersensitivity in polycythemia vera, we determined the expression of SHP-1 in highly purified erythroid progenitors from polycythemia vera patients. Our data demonstrate that in approximately 60% of the patients, expression of SHP-1 in the colony forming unit-erythroid population is diminished. The decreased expression of the protein may result from a transcriptional defect, as suggested by the diminished SHP-1 mRNA expression in the erythroid progenitors of these patients. Studies to determine the level of maturation of polycythemia vera and normal cells indicated that there was no difference between the two at early colony forming unit-erythroid stage of differentiation although polycythemia vera cells showed retarded differentiation kinetics at late colony forming unit-erythroid stage of differentiation. Furthermore, SHP-1 expression in normal colony forming unit-erythroid demonstrated downregulation of mRNA and protein levels during terminal differentiation, suggesting that its function is required for growth control during the early stages of erythropoiesis. These results indicate an important role for SHP-1 in the regulation of normal human erythroid progenitors and suggest that defective expression of the protein may contribute to the pathogenesis of polycythemia vera.

Reactivation of chronic Chagas' disease following allogeneic bone marrow transplantation and successful pre-emptive therapy with benznidazole

This report shows the early detection of reactivation of chronic Chagas' disease (CCd) in a 27-year-old man with chronic myelogenous leukemia undergoing allogeneic bone marrow transplantation (ABMT). Pre-emptive therapy with benznidazole during a period of 7 weeks led to a rapid recovery of the patient, who remains free of parasitemia 2 years after the bone marrow transplantation.

Isolation of differentially expressed genes by cloning transcriptionally active DNA fragments

During studies of erythroid cell growth and differentiation induced by erythropoietin (Epo), we developed a method that allows the identification and isolation of genes based upon their transcriptional activity. Transcriptionally active genomic DNA fragments from Epo-treated cells and control cells are purified from inactive chromatin using mercury affinity chromatography, based on the mechanism that the thiol groups of histone H3 on transcriptionally active chromatin are exposed to the solvent and therefore are easily accessible. Using the purified genomic DNA fragments from the two populations of cells, a subtractive hybridization strategy is used to isolate and clone genes that are differentially expressed in the absence or in the presence of Epo.

Arterial response to mild balloon injury in the normal rabbit: evidence for low proliferation rate in the adventitia

BACKGROUND

The role of constrictive remodeling, spasm and proliferation (particularly in the adventitia) in the genesis of chronic lumen narrowing after balloon injury remains under debate. This study analyzed the time course of these components following mild injury in normal arteries.

METHODS

Iliac injury was induced by balloon overstretch in 32 rabbits, sacrificed at timed intervals from day 3 to 28. Angiographic response to nitrates, morphometric, immunohistochemical and biochemical analysis were performed at each time point.

RESULTS

Quantitative angiography showed a decrease in lumen diameter and no change in response to nitrates over time. On morphometric analysis, remodeling was usually constrictive, appeared as early as day 3 and was responsible for 69+/-14% of the histologic lumen area stenosis at day 28. Constrictive remodeling was correlated negatively to intimal hyperplasia (r= 0.51, P< 0.002) and positively to the lumen area stenosis (r= 0.92, P< 0.0001). Macrophages (labeled by anti-RAM 11 antibodies) were very rare at all time points. Immunohistochemistry identified a high rate of proliferating smooth muscle cells in the media (13+/-7%) and intima (49+/-8%) at day 7, which decreased rapidly. Proliferating cells in the adventitia were rare (3+/-2% at day 7). The number of proliferating cells was time-dependent (r= 0.82, P< 0.0001) and related to cyclin A mRNA measured by reverse transcription-polymerase chain reaction (r= 0.84, P< 0.0001).

CONCLUSIONS

In this model, luminal loss was mainly caused by constrictive remodeling rather than intimal hyperplasia. Constrictive remodeling appeared early and was not time-dependent. Macrophages, spasm and adventitial proliferation did not contribute to this constrictive remodeling.

Effects of a self-management educational program for the control of childhood asthma

The objective of the present study was to evaluate the effects of a self-management educational program on 29 children between 6 and 14 years old and their parents implemented in an office setting in Venezuela. Children were randomly assigned to experimental and control group. Children's asthma knowledge, self-management abilities, index morbidity, parents' asthma knowledge and management abilities were measured. The program consisted of six sessions of information giving and cognitive-behavioral strategies for the children, and two talks and an informative brochure for the parents. Results of t tests indicate that the experimental group experienced a statistical significant effects on children's asthma knowledge (P < 0.001) and practice of self-management abilities (P < 0.000) and in parents' knowledge (P < 0.008) compared to the control group. The educational Self-management program had a significant impact on the Morbidity Index of the study group at post-test (P < 0.05). Younger children benefited more from the program compared to older ones (P < 0.09). Children's age is highlighted as a critical variable in designing asthma educational programs. Results suggest the effectiveness on these programs independently of the cultural context.

Alcohol use beliefs and behaviors among high school students

PURPOSE

To identify specific alcohol use beliefs and behaviors among local high school students; to determine whether relationships exist between alcohol use and various sociodemographic and lifestyle behaviors; and to assist in the development and implementation of alcohol abuse prevention programs.

METHODS

This cross-sectional study involved the completion of a questionnaire by 1236 Grade 9-13 students (86% response rate) from 62 randomly selected classrooms in three Canadian urban schools. Data analyzed here are part of a larger lifestyle survey.

RESULTS

A total of 24% of students reported never having tasted alcohol, 22% have tasted alcohol but do not currently drink, 39% are current moderate drinkers, 11% are current heavy drinkers (five or more drinks on one occasion at least once a month), and 5% did not answer. Reasons stated most often for not drinking were "bad for health" and "upbringing," while reasons stated most often for drinking were "enjoy it" and "to get in a party mood." Student drinking patterns were significantly related to gender, ethnicity, grade, and the reported drinking habits of parents and friends. Older male adolescents who describe their ethnicity as Canadian are at higher risk for heavy drinking than students who are younger or female, or identify their ethnicity as European or Asian. Current heavy drinkers are at higher risk than other students for engaging in other high-risk behaviors such as drinking and driving, being a passenger in a car when the driver is intoxicated, and daily smoking.

CONCLUSIONS

Heavy alcohol use in adolescents remains an important community health concern. Older self-described Canadian and Canadian-born male adolescents are at higher risk for heavy drinking. Current and heavy drinking rises significantly between Grades 9 and 12. Students who drink heavily are more likely to drink and drive, to smoke daily, and to have friends and parents who drink alcohol.

Frontal dysfunction in neurologically normal chronic alcoholic subjects: metabolic and neuropsychological findings

BACKGROUND

Neuropsychological and imaging studies suggest that frontal dysfunction may occur in apparently normal chronic alcoholic subjects.

METHODS

To investigate this issue further, we performed neuropsychological and fluorodeoxy-glucose-PET studies in 17 chronic alcoholics without patent neurological and psychiatric complications.

RESULTS

Metabolic abnormalities were found in the mediofrontal and in the left dorsolateral prefrontal cortex, but not in the orbitofrontal cortex. Neuropsychological testing revealed significantly reduced verbal fluency and impaired performance on the Stroop test. The mediofrontal hypometabolism correlated with the reduction in verbal fluency and the time necessary to perform the interference condition of the Stroop test. The left dorsolateral prefrontal hypometabolism correlated with the number of errors on the Stroop test.

CONCLUSION

These data indicate that circumscribed frontal dysfunctions may occur in chronic alcoholic subjects before clinically obvious neurological complications, and may account for some of the alcohol-related neuropsychological and behavioural impairments.

Expansion of clonotypic T-cell populations in the peripheral blood of asymptomatic Gran Chaco Amerindians infected with HTLV-IIB

Peripheral blood mononuclear cells from asymptomatic HTLV-II-infected and uninfected Gran Chaco Amerindians were analyzed using polymerase chain reaction (PCR) for expansions of T-cell receptor (TCR) V-beta gene clonotypes. Analyses were performed using primer pairs designed to identify expanded T-cell familial clonotypes based on their unique TCR beta gene rearrangements. Of the 30 HTLV-IIB-positive samples tested, five showed evidence of V-beta clonotypic T-cell expansion. Of the five expansions, two were monoclonotypic and the remaining three were oligoclonotypic. In comparison, 30 HTLV-II-negative Amerindians showed no evidence of clonotypic T-cell expansion. Amplified DNA from one of the monoclonotypic samples was subsequently cloned and sequenced and was found to have uniform variable/ diversity/joining sequences confirming its unique monoclonal T-cell expansion. This method of detecting clonal TCR beta gene rearrangements has the advantage over traditional Southern blot techniques of being more sensitive and specific even with suboptimal specimens. The prognostic significance of clonotypic T-cell expansion in a group such as the HTLV-II-infected Gran Chaco Amerindians remains to be determined.

[Gene therapy of restenosis]

Although angioplasty has undergone considerable development, restenosis remains an unsolved problem. No drugs have been proved effective in the prevention of restenosis. Prophylactic stenting is the only treatment with some efficacy. The pathophysiology of restenosis involves both intimal hyperplasia with a major proliferative component at the dilated site and geometric constrictive remodeling of the artery. Stenting seems to prevent the remodeling but does not prevent and may even worsen the intimal hyperplasia. Gene therapy may be effective in preventing the proliferative component of the intimal hyperplasia: therapeutic genes can be delivered locally to the arterial wall cells at the dilated site during or immediately after angioplasty, using viral (e.g., adenoviruses) or nonviral vectors. The main candidate genes stimulate a variety of endogenous mechanisms whose effects consist in inhibition of smooth muscle cell proliferation (Rb gene); sensitization of proliferating cells to the effects of cytotoxic substances, thus allowing selective chemotherapy (HSV-tk gene); or stimulation of reendothelization (VEGF gene). Other genes have also yielded promising results (ecNOs, p21, Coxl, etc.). Clinical application of these techniques cannot be envisioned until studies are available proving that the delivery methods (transfer vectors or local delivery systems) are completely safe, and that the candidate genes are effective in "realistic" models. If these hurdles are cleared successfully, preventive gene therapy for gene restenosis may well become a clinical reality.

Human erythropoietin dimers with markedly enhanced in vivo activity

Human erythropoietin, a widely used and important therapeutic glycoprotein, has a relatively short plasma half-life due to clearance by glomerular filtration as well as by other mechanisms. We hypothesized that an erythropoietin species with a larger molecular size would exhibit an increased plasma half-life and, potentially, an enhanced biological activity. We now report the production of biologically active erythropoietin dimers and trimers by chemical crosslinking of the conventional monomeric form. We imparted free sulfhydryl residues to a pool of erythropoietin monomer by chemical modification. A second pool was reacted with another modifying reagent to yield monomer with maleimido groups. Upon mixing these two pools, covalently linked dimers and trimers were formed that were biologically active in vitro. The plasma half-life of erythropoietin dimers in rabbits was >24 h compared with 4 h for the monomers. Importantly, erythropoietin dimers were biologically active in vivo as shown by their ability to increase the hematocrits of mice when injected subcutaneously. In addition, the dimers exhibited >26-fold higher activity in vivo than did the monomers and were very effective after only one dose. Dimeric and other oligomeric forms of Epo may have an important role in therapy.

Measuring postoperative complications in general surgery patients using an outcomes-based strategy: comparison with complications presented at morbidity and mortality rounds

BACKGROUND

This study was undertaken to compare the incidence of adverse postoperative outcomes recorded in a prospective general surgery database with that identified through weekly morbidity and mortality (M&M) rounds and to measure the impact of feedback of information to the providers of care.

METHODS

Data were collected on patients admitted to one general surgery service between October 1, 1995, and May 15, 1996, and recorded in a computer database. Postoperative complications were graded in severity from I (minor) to IV (mortality).

RESULTS

Of 479 admissions entered into the database during the study period, 325 (311 patients) led to operations and were further analyzed. Admissions resulting in complications were associated with longer hospital stays, regardless of complication grade, compared to uncomplicated admissions (p < 0.01). A total of 29 of 106 patients with postoperative complications were presented at M&Ms (27.4%). Whereas 15.4% of database patients with grade I complications were presented at M&Ms, this proportion increased to 22.2% for grade IIa, 34.8% for grade IIb, 33.3% for grade III, and 87.5% for grade IV. (p < 0.05 for grade I, IIa, and IIb compared to grade IV). A total of 58 of 142 patients in the first part of the study period developed complications (40.8%), compared to 53 of 183 patients in the second part of the study (29%, p = 0.034).

CONCLUSIONS

Although most severe complications are recorded at M&M rounds, a large proportion of complications remain unreported. Monitoring of outcomes may contribute to improvements in quality of care.

Reduction of restenosis after angioplasty in an atheromatous rabbit model by suicide gene therapy

BACKGROUND

Gene delivery of the thymidine kinase (tk) gene combined with ganciclovir (GCV) limits intimal hyperplasia after abrasion of normal arteries. However, the low efficiency of adenoviral-mediated gene transfer to atherosclerotic arteries has raised concerns about the applicability of this strategy to the prevention of restenosis.

METHODS AND RESULTS

A replication-defective adenoviral vector expressing tk (Ad-RSVtk) demonstrated selective toxicity toward GCV-treated arterial smooth muscle cells, with oligonucleolytic cleavage suggesting apoptosis. In vivo, after demonstration of tk expression after Ad-RSVtk delivery, the combination of Ad-RSVtk followed by GCV was tested in a rabbit model of angioplasty of atheromatous iliac arteries. Angioplasty (8 atm, 20 minutes) was performed by use of a hydrogel balloon coated with Ad-RSVtk (4x10(9) plaque forming units). GCV was infused (25 mg.kg(-1) I.V. BID) from days 2 through 7 after angioplasty in 8 of 12 rabbits. Four weeks later, morphometric analysis demonstrated a reduced intima-to-media ratio in the group receiving combination therapy compared with Ad-RSVtk alone (3.0+/-1.2 versus 5.2+/-0.5, P<.018). GCV per se had no effect on intimal hyperplasia after arterial injury.

CONCLUSIONS

In vitro, Ad-RSVtk demonstrates selective toxicity toward GCV-treated arterial smooth muscle cells involving apoptosis. In vivo, GCV conditions reduction of neointimal formation after percutaneous delivery of Ad-RSVtk during angioplasty of atheromatous arteries.