Can degenerative aortic valve stenosis be related to persistent Chlamydia pneumoniae infection?

BACKGROUND

The cause of age-related degenerative (tricuspid) aortic valve calcification is largely unknown, but one typical characteristic is an active inflammatory process. The presence of Chlamydia pneumoniae in aortic valve stenosis was recently shown.

OBJECTIVE

To test the hypothesis that if persistent C. pneumoniae infection plays an active role in the development of aortic stenosis, the organism can be detected in the healthy aortic valves of young persons.

DESIGN

A cadaver study.

SETTING

Oulu University Hospital, Oulu, Finland.

SUBJECTS

46 consecutive cadavers undergoing autopsy.

MEASUREMENTS

Macroscopic and histologic pathology of aortic valves was determined. The presence of C. pneumoniae was determined by immunohistochemistry.

RESULTS

34 of 46 valves were macroscopically normal. Early lesions of aortic valve disease were found in 12 valves (no lesions in valves from persons 20 to 40 years of age [n = 15], 4 lesions in valves from persons 41 to 60 years of age [n = 16], and 8 lesions in valves from persons older than 60 years of age [n = 15]; P = 0.004). Fifteen of 34 normal valves (44%) and 10 of 12 valves with early lesions (83%) had positive results on staining for C. pneumoniae (P = 0.02). In persons older than 60 years of age, the chance of an early lesion was higher if the valve tested positive for C. pneumoniae (7 of 8 valves with C. pneumoniae infection compared with 1 of 7 valves without C. pneumoniae infection; P = 0.01).

CONCLUSIONS

Chlamydia pneumoniae is frequently present in aortic valves and is associated with early lesions of aortic valve stenosis in elderly persons.

Cognitive function in an elderly population with persistent impaired glucose tolerance

OBJECTIVE

To study cognitive function in an elderly population with persistent impaired glucose tolerance (IGT).

RESEARCH DESIGN AND METHODS

Fasting and postload 2-h plasma glucose and insulin levels were determined at baseline in a population-based sample of 1,300 people and repeated an average of 3.5 years later in 980 subjects. At follow-up, cognitive function was evaluated in subjects with persistent normal glucose tolerance (NGT; n = 506) and IGT (n = 80) with a brief neuropsychological test battery.

RESULTS

Subjects with persistent IGT scored lower in the Mini-Mental State Examination (MMSE) and in the Buschke Selective Reminding Test long-term memory scores. Multiple linear regression analysis revealed that age, education, and insulin levels (either fasting or 2-h value) were associated with the MMSE score in subjects with persistent IGT. Other potential risk factors for impaired cognitive function were not significantly associated with the MMSE score.

CONCLUSIONS

Our study showed that persistent IGT in the elderly is associated with mildly impaired cognitive function, and hyperinsulinemia may account for this association.

New variants in the glycogen synthase gene (Gln71His, Met416Val) in patients with NIDDM from eastern Finland

Impaired glycogen synthesis after insulin stimulation accounts for most of the insulin resistance in patients with non-insulin-dependent diabetes mellitus (NIDDM). The glycogen synthase gene (GYS1), which encodes the rate-limiting enzyme for glycogen synthesis, is a promising candidate gene for NIDDM. Therefore, we screened all 16 exons of this gene by single-strand conformation polymorphism analysis in 40 patients with NIDDM (age 67 +/- 2 years, body mass index 28.2 +/- 0.6 kg/m2) from Taipalsaari, eastern Finland. The Gly464Ser variant (exon 11) and a silent polymorphism TTC342TTT (exon 7) have been reported previously. In addition, we found a new variant Gln71His (exon 2) and a new amino acid polymorphism Met416Val (exon 10). An additional sample of 65 patients with NIDDM and 82 normoglycaemic men (age 54 +/- 1 years, body mass index 26.3 +/- 1.4 kg/m2) were screened. The allele frequency of the TTC342TTT silent substitution was 0.29 in both NIDDM and normoglycaemic subjects. The Gln71His and Gly464Ser variants were found in 1 (1%) and 3 (3%) subjects, respectively, of the 105 NIDDM patients and in none of the 82 normoglycaemic men. The Met416Val polymorphism was found in 16 (15%) of the 105 NIDDM patients and in 14 (17%) of the 82 control subjects (all heterozygous). The Met416Val polymorphism was not associated with insulin resistance in two groups of normoglycaemic subjects. In conclusion, the new Gln71His and Met416Val substitutions and other variants of the glycogen synthase gene are unlikely to make a major contribution to insulin resistance and NIDDM in diabetic patients from eastern Finland.

Association between features of the insulin resistance syndrome and Alzheimer's disease independently of apolipoprotein E4 phenotype: cross sectional population based study

OBJECTIVE

To determine the association between features of the insulin resistance syndrome and Alzheimer's disease.

DESIGN

Cross sectional population based study.

SUBJECTS

980 people aged 69 to 78 (349 men, 631 women).

SETTING

Population of Kuopio, eastern Finland.

MAIN OUTCOME MEASURES

Presence of features of the insulin resistance syndrome and diagnosis of Alzheimer's disease by detailed neurological and neuropsychological evaluation.

RESULTS

46 (4.7%) subjects were classified as having probable or possible Alzheimer's disease. In univariate analyses, apolipoprotein E4 phenotype (odds ratio; 95% confidence interval 3.24: 1.77 to 5.92), age (1.16; 1.05 to 1.29), low level of education (0.82; 0.72 to 0.93), low total cholesterol concentration (0.77; 0.59 to 1.00), high systolic blood pressure (1.01; 1.00 to 1.03), high fasting and 2 hour plasma glucose concentrations (1.11; 1.01 to 1.23 and 1.08; 1.03 to 1.13, respectively), high fasting and 2 hour insulin concentrations (1.05; 1.02 to 1.08 and 1.003; 1.00 to 1.01, respectively), and abnormal glucose tolerance (1.86; 1.23 to 2.80) were significantly associated with Alzheimer's disease. In multivariate analysis including apolipoprotein E4 phenotype, age, education, systolic blood pressure, total cholesterol concentration, fasting glucose concentration, and insulin concentration, apolipoprotein E4 phenotype, age, education, total cholesterol, and insulin were significantly associated with Alzheimer's disease. In 532 non-diabetic subjects without the e4 allele hyperinsulinaemia was associated with an increased risk for Alzheimer's disease (prevalence of disease 7.5% v 1.4% in normoinsulinaemic subjects, P = 0.0004). In contrast, in the 228 with the e4 allele hyperinsulinaemia had no effect on the risk of disease (7.0% v 7.1%, respectively).

CONCLUSION

Features of the insulin resistance syndrome are associated with Alzheimer's disease independently of apolipoprotein E4 phenotype.

The Trp64Arg polymorphism of the beta 3-Adrenergic receptor gene. Lack of association with NIDDM and features of insulin resistance syndrome

OBJECTIVE

To investigate the association of the Trp64Arg polymorphism of the beta3-adrenergic receptor gene with NIDDM and the features of insulin resistance syndrome in subjects from eastern Finland.

RESEARCH DESIGN AND METHODS

We determined the prevalence of the Trp64Arg polymorphism of the beta3-adrenergic receptor gene by restriction fragment length polymorphism analysis in 110 patients with NIDDM (54 men and 56 women, age 63 +/- 1 years, BMI 30.4 +/- 0.5 kg/m2), in 183 patients with features of insulin resistance syndrome (103 men and 80 women, age 44 +/- 0 years, BMI 31.1 +/- 0.4 kb/m2), and in 82 normoglycemic control men (age 54 +/- 1 years, BMI 26.3 +/- 0.4 kg/m2).

RESULTS

The allele frequency of the Trp64Arg polymorphism of the beta3-adrenergic receptor gene was similar in patients with NIDDM, in patients with insulin resistance syndrome, and in control subjects (0.08, 0.07, and 0.07, respectively; NS). In addition, this polymorphism was not associated with low resting metabolic rate, abdominal obesity, increased lipid oxidation, hypertension, or earlier development of NIDDM as previously described. Furthermore, in 82 normoglycemic male control subjects the Trp64Arg polymorphism was not associated with insulin resistance evaluated by the euglycemic-hyperinsulinemic clamp.

CONCLUSIONS

The Trp64Arg polymorphism of the beta 3-adrenergic receptor gene is unlikely to be a major genetic predisposer to NIDDM or insulin resistance syndrome in subjects from eastern Finland.

The Ala54Thr polymorphism of the fatty acid binding protein 2 gene does not influence insulin sensitivity in Finnish nondiabetic and NIDDM subjects

Insulin resistance and hyperinsulinemia are major predictors of NIDDM. Since several studies have demonstrated that heredity plays a significant role in the development of insulin resistance (1), defects in genes that regulate insulin action could potentially contribute to the risk of NIDDM. A locus on chromosome 4q has been shown to be linked with fasting insulin levels (2), 2-h insulin levels (3,4), and insulin action (2) in Pima Indians and Mexican-Americans, suggesting that the fatty acid binding protein 2 (FABP2) gene is a promising candidate gene for insulin resistance and NIDDM.

Detection of Chlamydia pneumoniae in human nonrheumatic stenotic aortic valves

OBJECTIVES

We sought to study the possible presence of Chlamydia pneumoniae in aortic valve stenosis (AVS).

BACKGROUND

Inflammation and immune mechanisms are considered important for the pathogenesis of nonrheumatic AVS. All chlamydial species are able to cause heart infections, and seroepidemiologic studies have indicated an association between chronic C. pneumoniae infection and coronary artery disease. Furthermore, the organism has been demonstrated in atherosclerotic lesions.

METHODS

Aortic valve specimens with varying degrees of macroscopic disease were obtained from 35 subjects--17 consecutive patients undergoing aortic valve replacement for treatment of nonrheumatic AVS and 18 age-matched subjects at autopsy. The possible presence of C. pneumoniae in aortic valves was studied by immunohistochemical analysis, polymerase chain reaction or transmission electron microscopy, or a combination of these.

RESULTS

Positive immunohistochemical staining with C. pneumoniae specific antibody was found in 9 (53%) of 17 patients with advanced aortic valve disease requiring surgical treatment (group A), 8 (80%) of 10 cadavers with clearly macroscopic aortic valve pathology (group B) and 1 (12%) of 8 grossly normal cadaver control subjects (group C). Statistical significance with regard to the presence of C. pneumoniae was found when combined diseased subjects (groups A and B: total 17 of 27 subjects) were compared with group C (p = 0.018). However, when group A was compared with group C, there was only marginal statistical significance (p = 0.088). Finally, there was a strong statistical significance (p = 0.015) when groups B and C were compared. Chlamydia pneumoniae DNA was also found in three stenotic valves, and in two of the three tested valve specimens chlamydia-like particles were seen by electron microscopy.

CONCLUSIONS

Chlamydia pneumoniae is frequently present in nonrheumatic AVS. Similarly, the high number of C. pneumoniae infections detected in the early lesions of "degenerative" AVS suggest that this pathogen may play an etiologic role in the development of this disease. The validity of this relation requires additional study.

Epidemiological evidence for the association of hyperglycaemia and atherosclerotic vascular disease in non-insulin-dependent diabetes mellitus

Non-insulin-dependent diabetes mellitus (NIDDM) increases the risk for all manifestations of atherosclerotic vascular disease, coronary heart disease (CHD), cerebrovascular disease and peripheral vascular disease. Only a small proportion of this excess risk can be explained by the effects of conventional cardiovascular risk factors, which implies that the diabetic state or factors related to it have to play a significant role in the pathogenesis of macrovascular disease in NIDDM. Six recent prospective population-based studies including a large number of NIDDM patients have indicated that poor glycaemic control evaluated by fasting hyperglycaemia or glycosylated haemoglobin levels increases the risk for CHD, stroke and amputation independently of other risk factors. A dose-response relationship between markers of glycaemic control and the incidence of cardiovascular mortality and morbidity has been demonstrated in all these studies. However, there is so far no direct proof that strict glycaemic control would delay or prevent atherosclerotic complications.

Apolipoproteins B, (a), and E accumulate in the morphologically early lesion of 'degenerative' valvular aortic stenosis

Nonrheumatic aortic stenosis of trileaflet aortic valves has been considered to be a "degenerative" process, but the early lesion of aortic stenosis contains the chronic inflammatory cells, macrophages and T lymphocytes. Because lipoprotein deposition is prominent in atherosclerosis, another chronic inflammatory process, this study examined whether lipoproteins accumulate in aortic valve lesions. Immunohistochemical studies were performed to detect apolipoprotein (apo) B, apo(a), apoE, macrophages, and alpha-actin-expressing cells on 18 trileaflet aortic valves that ranged from normal to stenotic. All three apolipoproteins were detected in early through end-stage lesions of aortic stenosis but not in histologically normal regions. Comparison with oil red O staining suggested that most of the extracellular neutral lipid in these valves was associated with either plasma-derived or locally produced apolipoproteins. Thus, in early through end-stage aortic valve lesions, apolipoproteins accumulate and are associated with the majority of extracellular valve lipid. These results are consistent with the hypothesis that lipoprotein accumulation in the aortic valve contributes to pathogenesis of aortic stenosis.

Retroperitoneal fibrosis with antineutrophil cytoplasmic antibodies

A middle aged man showed retroperitoneal fibrosis with signs of vasculitis verified by biopsy of the retroperitoneal mass. Antineutrophil cytoplasmic antibodies (ANCA) with cytoplasmic staining pattern (cANCA) were strongly positive, although there were no clinical or histological signs of Wegener's granulomatosis. No cases of cANCA associated retroperitoneal fibrosis have been described except in connection with Wegener's granulomatosis. ANCA have been found to associate with any inflammatory disorders. This observation may broaden the clinical spectrum of cANCA positive vasculitides.

Memory functions in human subjects with different apolipoprotein E phenotypes during a 3-year population-based follow-up study

The apolipoprotein E epsilon4 allele is the most common risk factor for Alzheimer's disease (AD). The epsilon2 allele may play a protective role in AD. Our previous cross-sectional study showed that in non-demented elderly subjects the epsilon2 allele is associated with better learning ability than other alleles. We wished to investigate the influence of different apolipoprotein E (apoE) phenotypes on cognitive functions in a 3-year follow-up study starting with a random sample of 917 non demented elderly subjects. Episodic memory was examined with the List Learning Test (Buschke's selective reminding method), as well as with immediate and delayed recall of figures. Retrieval from semantic memory was assessed with the Category and Verbal Fluency tests. Constructional abilities were examined by copying figures. Attention functions were examined with the Trail Making A and B tests. A total of 632 subjects completed the 3-year follow-up study. The subjects with apoE phenotypes E2/2 or E2/3 were able to maintain their verbal learning performance, while the learning ability of the subjects with other apoE phenotypes deteriorated. We suggest that successful mental aging may be at least in part associated with genetic factors.

Gender differences in left ventricular function at rest and with exercise in asymptomatic aortic stenosis

In 29 women and 53 men with asymptomatic aortic stenosis, two-dimensional (2-D) and Doppler echocardiography were performed at rest and immediately after treadmill exercise testing to examine gender differences in left ventricular geometry, systolic and diastolic function, functional status, and exercise capacity. Aortic stenosis severity was similar between men and women. Women reported more functional impairment than men (88% +/- 14% vs 95% +/- 7%; p = 0.02). When indexed to body surface area, women had a smaller end-diastolic volume (39 +/- 14 vs 50 +/- 15 ml/m2; p = 0.002), end-systolic volume (13 +/- 6 ml/m2 vs 18 +/- 9 ml/m2; p = 0.01) and left ventricular mass (73 +/- 26 gm/m2 vs 84 +/- 21 gm/m2; p = 0.05), but a higher relative wall thickness in systole (1.5 +/- 0.4 cm vs 1.3 +/- 0.4 cm; p = 0.05), and fractional shortening (43% +/- 7% vs 39% +/- 10%; p = 0.03). Women had higher early and late transmitral velocities than did men (early, 92 +/- 24 cm/sec vs 79 +/- 29 cm/sec; p = 0.05; late, 97 +/- 30 cm/sec vs 68 +/- 23 cm/sec; p < 0.0001), a higher time-velocity integral in early diastole (18.2 +/- 4.8 cm vs 15.1 +/- 4.3 cm; p = 0.006), a significantly shorter exercise duration (4.5 +/- 4.1 minutes vs 8.0 +/- 3.9 minutes; p < 0.0001), a greater degree of functional aerobic impairment (25% +/- 48% vs 2% +/- 33%; p = 0.02), and a smaller increase in cardiac output with exercise (5.4 +/- 3.5 L/min vs 8.0 +/- 4.3 L/min; p = 0.01), in spite of similar peak heart rate and blood pressure responses. In these asymptomatic subjects with aortic stenosis, women had smaller, relatively hypercontractile ventricles, a different diastolic filling profile, more exercise limitation, and poorer functional capacity. These findings demonstrate the importance of gender in the response of the left ventricle to chronic pressure overload.

Osteopontin is expressed in human aortic valvular lesions

BACKGROUND

Nonrheumatic stenosis of trileaflet aortic valves, in which calcification is a prominent feature, has been termed a "degenerative" condition, but it has been demonstrated recently that chronic inflammation is a characteristic feature of the developing lesion of aortic stenosis. This observation raised the possibility that calcification in the aortic valve might be actively regulated. Thus, the present study investigated whether osteopontin, a protein implicated in the regulation of both normal and dystrophic calcification, could be detected in lesions of valvular aortic stenosis.

METHODS AND RESULTS

Morphological and immunohistochemical studies were performed on 14 human aortic valves, representing a range of pathology from normal to clinically stenotic. The extent of calcification and macrophage accumulation and their relation to the presence of osteopontin protein were characterized. Highly statistically significant associations were found between the degree of osteopontin expression and the degrees of both calcification and macrophage accumulation in early through late lesions of aortic stenosis. Further, in situ hybridization localized osteopontin mRNA to a subset of lesion macrophages.

CONCLUSIONS

These results suggest that, rather than representing a degenerative and unmodifiable process, calcification in aortic stenosis may be, in part, an actively regulated process with the potential for control either through modification of inflammation or synthesis of proteins such as osteopontin, which may modulate calcification in this tissue.

Prospective study of small LDLs as a risk factor for non-insulin dependent diabetes mellitus in elderly men and women

BACKGROUND

The excess risk of atherosclerosis among patients with non-insulin dependent diabetes mellitus (NIDDM) is well documented. However, the presence of conventional risk factors cannot fully account for this excess risk, and the underlying mechanism remains to be elucidated. The present study prospectively evaluated the role of small LDL, a known risk factor for coronary heart disease, as a risk factor for the development of NIDDM.

METHODS AND RESULTS

The study was based on a nested case-control sample of 204 elderly men and women from Kuopio, Finland. LDL subclasses were characterized by size with 2% to 14% polyacrylamide gels produced by recently developed methods. Logistic regression analysis showed that subjects with a predominance of small LDL (LDL subclass phenotype B) had a greater than two fold increased risk for developing NIDDM over the 3.5-year follow-up period. This association was independent of age, sex, glucose intolerance, and body mass index but was not independent of fasting triglyceride or insulin levels. Further, an increase of 5A in LDL diameter was associated with a 16% decrease in risk of NIDDM, and a composite variable of LDL diameter and triglyceride and HDL cholesterol concentrations, identified by principal-components analysis, was also associated with NIDDM. These associations may be attributable to the role of small LDL as a marker for insulin resistance.

CONCLUSIONS

This study is the first to demonstrate that a predominance of small LDL particles is a risk factor for the future development of NIDDM, and it implies that small LDL contributes to risk of coronary heart disease in prediabetics.

Serum proinsulin levels are disproportionately increased in elderly prediabetic subjects

Insulin resistance and impaired insulin secretion are thought to be the primary defects in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). Disproportionately increased proinsulin relative to insulin levels are suggested to be an early indicator of a failing pancreas. We examined the relationship of fasting specific insulin, proinsulin, and 32, 33 split proinsulin concentrations, and the proinsulin: insulin ration to the risk of developing NIDDM 3.5 years later in 65-74-year-old non-diabetic Finnish subjects participating in a population-based study (n=892) on diabetes and heart disease. Altogether 69 subjects developed NIDDM over a 3.5-year follow-up (cases). The cases were compared to randomly-selected gender-matched control subjects (n=69) and control subjects matched for gender, glucose tolerance status (normal or impaired), and body mass index (n=69). There were no differences in insulin concentrations between cases and random or matched control subjects [median and interquartile range: 123 (77-154), 108 (74-143), 118 (83-145) pmol/l, p=0.271]. Random control subjects had lower proinsulin and 32, 33 split proinsulin concentrations and split proinsulin: insulin ratios compared to cases [5.7 (3.8-9.0) vs 7.3 (4.8-10.0) pmol/l, p=0.005; 7.3 (4.5-13.0 vs 10.4 (7.1-18.0) pmol/l, p=0.002; 0.073 (0.057-0.110) vs 0.097 (0.060- 0.135), p=0.003]. Matched control subjects had lower proinsulin concentrations and proinsulin: insulin ratios compared to cases [5.9 (4.0-7.7) vs 7.3 (4.8-10.0) pmol/l, p=0.019; 0.048 (0.035-0.071) vs 0.064 (0.045-0.100), p=0.008]. When cases were compared to matched control subjects a 1 SD increase in baseline proinsulin: insulin ratio was associated with a 1.37-fold risk (p=0.020) of developing diabetes. Moreover, this association was independent of fasting glucose concentration at baseline. Thus, in elderly prediabetic subjects disproportionately increased proinsulin concentration, an indicator of defective insulin secretion, is associated with conversion to diabetes over a short time period.

Apolipoprotein E4 phenotype is not an important risk factor for coronary heart disease or stroke in elderly subjects

The allele e4 (apo e4) of apolipoprotein E (apo E) has been associated with an increased risk for coronary heart disease (CHD) in cross-sectional studies in middle-aged subjects. We investigated the risk of CHD and stroke with respect to the number of apo e4 alleles in a prospective study of a Finnish nondiabetic cohort including 1067 subjects 65 to 74 years old at baseline. During the 3.5-year follow-up, CHD mortality was 2.8%, total CHD incidence 6.9%, and the cumulative occurrence of CHD (prevalence at baseline and the 3.5-year incidence combined) 17.0%. The incidence of stroke was 3.4%, and the cumulative occurrence of stroke was 6.0%. The CHD mortality was 3.4% in subjects with no apo e4 allele (n = 734), 1.7% in those with one apo e4 allele (n = 296), and 0% in subjects with two apo e4 alleles (n = 37) (P = NS between the three groups). The incidence of CHD according to the number of apo e4 alleles was 6.9% (no apo e4 alleles), 7.4% (one apo e4 allele), and 2.7% (two apo e4 alleles), and the cumulative occurrence of CHD was 16.5%, 18.6%, and 13.5%, respectively (P = NS). The incidence of stroke was 3.8% in subjects with no apo e4 allele, 2.7% in those with one apo e4 allele, and 0% in those with two apo e4 alleles (P = NS). The cumulative occurrence of stroke was 6.0%, 6.4%, and 2.7%, respectively (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

The association of apolipoprotein E polymorphism with memory: a population based study

Several studies have shown an association between the apolipoprotein epsilon 4 allele and Alzheimer's disease (AD). The allele epsilon 2 has been associated with survival and longevity. We wanted to examine whether the relationship between cognitive efficiency and apolipoprotein E polymorphism (APOE) exists in a random sample of 916 non-demented elderly subjects. Episodic memory was examined with the list learning test, and with immediate and delayed recall of the figures. Semantic memory was examined with the Category and Verbal Fluency Tests. Constructional abilities were examined by copying the figures. Attention functions were examined with Trail Making A and B tests. We found that subjects with APOE E2/2 and 2/3 phenotypes showed better learning ability than those subjects with the APOE E2/4, 3/4 or 4/4 phenotypes. Impaired memory was not related to the excess of cardiovascular diseases in the subjects with APOE E2/4, 3/4, 4/4 phenotypes. Thus they may be associated, at least partly, with genetic factors.

Polymorphisms of the human hexokinase II gene: lack of association with NIDDM and insulin resistance

Skeletal muscle and adipose tissue hexokinase II is a promising candidate gene for non-insulin-dependent diabetes mellitus (NIDDM) and insulin resistance. Therefore, we investigated the association of alleles at four polymorphic loci in this gene with NIDDM and insulin resistance in 110 Finnish diabetic patients with NIDDM and in 97 Finnish control subjects with normal glucose tolerance and a negative family history of diabetes. The four polymorphic nucleotide substitutions (silent) in the coding region of the hexokinase II gene were: GAC 251 GAT (exon 7), AAC 692 AAT and CCG 736 CCC (exon 15), and CTG 766 CTA (exon 16). Allele frequencies of each of these polymorphisms did not differ between patients with NIDDM and control subjects. In addition, subjects who were homozygous for the less frequent allele of each of the four polymorphisms had a similar degree of insulin resistance, as determined by the euglycaemic clamp technique, as did the subjects who were homozygous for the common allele in both control subjects and in patients with NIDDM. In conclusion, polymorphisms in the hexokinase II gene are not associated with the risk of NIDDM or insulin resistance in the Finnish population.

Improvement of metabolic control does not normalize auditory brainstem latencies in subjects with insulin-dependent diabetes mellitus

INTRODUCTION

In our previous study (Am J Otolaryngol 14:413-418, 1993), we reported that prolonged auditory brainstem response latencies are associated with microvascular complications and the duration of diabetes in patients with insulin-dependent diabetes mellitus (IDDM). To investigate whether short-term improvement in metabolic control also affects ABR-responses, we compared ABR-latencies in subjects with IDDM before and after intensified insulin and diet therapy.

MATERIALS AND METHODS

Auditory brainstem latencies were measured in 13 subjects with IDDM (mean age: 25 years) before and after intensified insulin and diet therapy. The acoustic stimulus was a half sine wave with a duration of 0.250 millisecond and a frequency of 2,000 Hz. The stimulus was presented monaurally with fixed polarity through shielded headphones TDH-39 at repetition rate of 10 Hz and at 90 dB hearing level. All subjects had normal hearing ability. Glycated hemoglobin A1C (GHbA1C), blood glucose immediately before ABR-measurements, and mean blood glucose during 24 hours before auditory studies were measured before and after intensified therapy.

RESULTS

During intensified insulin therapy, GHbA1C improved significantly (P < .05) in study subjects. However, no changes were observed in ABR-latencies. We also studied those 10 patients whose blood glucose improved during intensified insulin therapy. Although blood glucose was significantly lower (P < .01) after intensified insulin therapy compared with that at baseline, no changes were observed between ABR-latencies at baseline and follow-up.

CONCLUSION

ABR-latencies were not affected by improvement in metabolic control in patients with IDDM. Our finding suggests that delayed ABR-latencies found in patients with IDDM are not caused by poor metabolic control of diabetes but rather by other mechanisms, for example, microvascular complications.

Glucokinase gene variants in subjects with late-onset NIDDM and impaired glucose tolerance

OBJECTIVE

To investigate the frequency of variants of the glucokinase (GCK) gene in subjects with late-onset non-insulin-dependent diabetes mellitus (NIDDM) and in subjects with late-onset impaired glucose tolerance (IGT).

RESEARCH DESIGN AND METHODS

The study population included 36 Finnish patients with late-onset NIDDM who were treated with diet for > 8 years or who were newly diagnosed and 40 subjects with late-onset IGT who had low or normal insulin levels when tested by an oral glucose tolerance test. All exons, exon-intron junctions, and islet and liver promotor regions of the GCK gene were amplified with the polymerase chain reaction and screened for mutations using single-strand conformation polymorphism analysis.

RESULTS

A silent third-base substitution (TAC: >TAT) in codon 215 of exon 6 was found in 2.8% of NIDDM patients and in 5.0% of IGT subjects. Polymorphisms were found in islet exon 1 at nucleotide 403 (C-->G) in 16.7% of NIDDM patients and in 17.5% of IGT subjects and in the noncoding region of the islet promotor at nucleotide -30 (G-->A) in 13.9% of NIDDM patients and in 25.0% of IGT subjects. Furthermore, in liver intron 1 a variant (C-->T), 12 base pairs upstream from the splice acceptor site, was found in 5.6% of NIDDM patients and in 7.5% of IGT subjects.

CONCLUSIONS

These results indicate that the mutations in the coding region of the GCK gene are not likely to play a major role the pathogenesis of late-onset NIDDM or IGT in the Finnish population.

Hyperinsulinemic microalbuminuria. A new risk indicator for coronary heart disease

BACKGROUND

Both hyperinsulinemia and microalbuminuria have been shown to increase coronary heart disease (CHD) risk, but the interaction among hyperinsulinemia, microalbuminuria, and the risk for CHD has not been investigated in previous studies.

METHODS AND RESULTS

The risk of CHD in relation to hyperinsulinemia and microalbuminuria was examined in a cohort of 1069 elderly nondiabetic subjects from Kuopio, east Finland, during 3.5 years of follow-up. The overall incidence of CHD death was 2.8%, and 6.9% of study subjects died of CHD or had a nonfatal myocardial infarction (later referred to as all CHD events). In the highest fasting-insulin quintile (fasting insulin > or = 114.0 pmol/L), there was a slightly but insignificantly higher incidence rate of both CHD mortality and all CHD events compared with lower quintiles. The incidence rates of CHD mortality and all CHD events were significantly higher in the highest urinary albumin/creatinine ratio (ACR) quintile (ACR > or = 3.22 mg/mmol) compared with lower quintiles (P < .05 and P < .01, respectively). Hyperinsulinemic microalbuminuria (simultaneous presence of fasting insulin > or = 114.0 pmol/L and ACR > or = 3.22 mg/mmol) markedly increased the risk of CHD mortality (12.5%, P < .001) and all CHD events (18.8%, P < .001) compared with normoinsulinemic subjects without microalbuminuria (2.2% and 5.8%, respectively). In univariate logistic regression analyses, hyperinsulinemic microalbuminuria was a strong predictor of both CHD death (odds ratio [OR], 5.93; P < .001) and all CHD events (OR, 3.39; P = .002). Multivariate logistic regression analyses were also performed, including sex, current smoking, waist-hip ratio, systolic blood pressure, and HDL cholesterol, with insulin, ACR, or both as independent variables. Even after adjustment for these variables, hyperinsulinemic microalbuminuria remained a strong predictor of CHD death (OR, 7.91; P < .001) and all CHD events (OR, 2.95; P = .014). The group with hyperinsulinemic microalbuminuria was characterized by the most adversely affected risk factor pattern (high triglycerides > or = 2.3 mmol/L, low HDL cholesterol < or = 0.9 mmol/L in men and < or = 1.20 mmol/L in women, and hypertension).

CONCLUSIONS

Simultaneous occurrence of hyperinsulinemia and microalbuminuria identifies a group of subjects with a highly increased risk for CHD in elderly nondiabetic subjects.

Increased risk of non-insulin-dependent diabetes mellitus in elderly hypertensive subjects

BACKGROUND

In several studies hypertension has been shown to be associated with an increased incidence of non-insulin-dependent diabetes mellitus (NIDDM). This may be due to hypertension itself or to the deleterious effects of some antihypertensive agents on glucose tolerance and insulin sensitivity.

METHODS

We examined the 3.5-year incidence of diabetes mellitus in relation to hypertension and antihypertensive medication in a population-based study of elderly subjects (n = 805) aged 65-74 years in Kuopio, Finland.

RESULTS

Of the subjects studied, 60% had hypertension at baseline and 50% of the hypertensive subjects were on drug therapy at baseline. Hypertensive subjects had a significantly higher incidence of NIDDM than non-hypertensive subjects. However, after adjustment for age, body mass index, waist: hip ratio, sex, and fasting glucose and insulin levels, the increased risk of NIDDM in hypertensive subjects was no longer statistically significant. Subjects with high blood pressure (> or = 160/95 mmHg) at the baseline examination who were not taking beta-blockers or diuretic medication had a 1.56-fold increased risk of developing NIDDM, whereas subjects with hypertension who were taking those agents had a 1.88-fold risk of developing NIDDM compared with subjects with normal blood pressure. The risk of developing NIDDM was accompanied by elevated fasting insulin levels. After adjustment for age, sex, body mass index, waist:hip ratio, and fasting glucose and insulin levels, hypertensive subjects taking diuretics or beta-blockers, or both, still had a 1.56-fold increased risk of developing NIDDM relative to normotensive subjects. Hypertensive subjects taking diuretics or beta-blockers, or both, had a significantly higher incidence of NIDDM than hypertensive subjects not on pharmacological therapy. However, after adjustment for 2-h glucose and insulin concentrations, the incidence of NIDDM did not differ between the hypertensive subjects.

CONCLUSION

The data presented suggest that the increased risk of NIDDM in hypertensive subjects taking beta-blockers or diuretics, or both, is explained at least partly by metabolic disturbances related to drug therapy.

Association of apolipoprotein E phenotypes with late onset Alzheimer's disease: population based study

OBJECTIVE

To determine the association between the e4 allele of apolipoprotein E and Alzheimer's disease in a randomly selected population sample.

DESIGN

Cross sectional population based study.

SUBJECTS

980 people aged 69 to 78 (349 men, 631 women).

SETTING

Population of Kuopio, eastern Finland.

MAIN OUTCOME MEASURES

Presence of e4 allele and diagnosis of Alzheimer's disease by detailed neurological and neurophysiological evaluation.

RESULTS

46 (4.7%) subjects were classified as having probable or possible Alzheimer's disease. The frequency of the apolipoprotein E e4 allele was 0.359 in patients with Alzheimer's disease and 0.165 subjects without dementia (P < 0.0001). The prevalence of Alzheimer's disease was 2.9% in subjects with no e4 alleles, 7.6% in subjects with one e4 allele, and 21.4% in subjects with two e4 alleles of apolipoprotein E.

CONCLUSIONS

Allele e4 of apolipoprotein is associated with Alzheimer's disease in a dose-response fashion in a randomly selected elderly population.

Insulin receptor substrate-1 variants in non-insulin-dependent diabetes

Insulin receptor substrate-1 (IRS-1) plays an important role in insulin-stimulated signaling mechanisms. Therefore, we investigated the frequency and clinical significance of variants in the coding region of this gene in patients with non-insulin-dependent diabetes (NIDDM). Initial screening included a population-based sample of 40 Finnish patients with typical NIDDM. Applying single strand conformation polymorphism analysis the following amino acid substitutions were found among the 40 NIDDM patients: Gly818-Arg, Ser892Gly, and Gly971Arg. The first two variants have not been previously reported. Additional samples of 72 patients with NIDDM and 104 healthy control subjects with completely normal oral glucose tolerance test and a negative family history of diabetes were screened. The most common polymorphism was the Gly971Arg substitution which was found in 11 (9.8%) of 112 NIDDM patients and in 9 (8.7%) of 104 control subjects. The Gly818Arg substitution was found in 2 (1.8%) of NIDDM patients and in 2 (1.9%) of control subjects, and the Ser892Gly substitution was found in 3 (2.7%) NIDDM patients and in 1 (1.0%) control subject. The Gly971Arg substitution was not associated with an impairment in insulin secretion capacity (estimated by insulin responses in an oral glucose tolerance test or by the hyperglycemic clamp) or insulin action (estimated by the euglycemic clamp). Of the three amino acid substitutions observed Ser892Gly is the most interesting one since it abolishes one of the potential serine phosphorylation sites (SPGE) which is located immediately NH2-terminal to the only SH2 binding site of growth factor receptor-bound protein (GRB2), and thus could potentially influence some aspects of signal transduction and metabolic response to insulin.

Characterization of the early lesion of 'degenerative' valvular aortic stenosis. Histological and immunohistochemical studies

BACKGROUND

Nonrheumatic stenosis of trileaflet aortic valves, often termed senile or calcific valvular aortic stenosis, is considered a "degenerative" process, but little is known about the cellular or molecular factors that mediate its development.

METHODS AND RESULTS

To characterize the developing aortic valvular lesion, we performed histological and immunohistochemical studies on Formalin-fixed and methanol-Carnoy's-fixed paraffin-embedded aortic valve leaflets or on frozen sections obtained at autopsy from 27 adults (age, 46 to 82 years) with normal leaflets (n = 6), mild macroscopic leaflet thickening (n = 15), or clinical aortic stenosis (n = 6). Focal areas of thickening ("early lesions") were characterized by (1) subendothelial thickening on the aortic side of the leaflet, between the basement membrane (PAS-positive) and elastic lamina (Verhoeff-van Gieson), (2) the presence of large amounts of intracellular and extracellular neutral lipids (oil red O) and fine, stippled mineralization (von Kossa), and (3) disruption of the basement membrane overlying the lesion. Regions of the fibrosa adjacent to these lesions were characterized by thickening and by protein, lipid, and calcium accumulation. Control valves showed none of these abnormalities. Immunohistochemical studies were performed using monoclonal antibodies directed against macrophages (anti-CD68 or HAM-56), and contractile proteins of smooth muscle cells or myofibroblasts (anti-alpha-actin and HHF-35) or rabbit polyclonal antiserum against T lymphocytes (anti-CD3). In normal valves, scattered macrophages were present in the fibrosa and ventricularis, and occasional muscle actin-positive cells were detected in the proximal portion of the ventricularis near the leaflet base, but no T lymphocytes were found. In contrast, early lesions were characterized by the presence of an inflammatory infiltrate composed of non-foam cell and foam cell macrophages, occasional T cells, and rare alpha-actin-positive cells. In stenotic aortic valves, a similar but more advanced lesion was seen.

CONCLUSIONS

The early lesion of "degenerative" aortic stenosis is an active inflammatory process with some similarities (lipid deposition, macrophage and T-cell infiltration, and basement membrane disruption) and some dissimilarities (presence of prominent mineralization and small numbers of smooth muscle cells) to atherosclerosis.

NIDDM and its metabolic control predict coronary heart disease in elderly subjects

The aim of this study was to evaluate whether noninsulin-dependent diabetes (NIDDM) and its metabolic control and duration predict coronary heart disease (CHD) events during a 3.5-year follow-up in a randomly selected Finnish population sample 65-74 years of age at baseline. Of 1,298 subjects participating in the baseline study, 1,069 were nondiabetic and 229 had NIDDM. During the follow-up, 3.4% of nondiabetic and 14.8% of NIDDM subjects died from CHD or had a nonfatal myocardial infarction (MI). The impact of NIDDM on CHD mortality and morbidity was more marked in women than in men. Odds ratios (ORs) and their 95% confidence intervals for CHD death and nonfatal MI in women with NIDDM compared with women with normal glucose tolerance were 11.7 (3.8-36.4) and 4.7 (3.6-6.1). In men, the corresponding ORs were 0.43 (0.1-1.9) and 1.4 (0.6-3.2). In multiple logistic regression analyses including all study subjects, NIDDM (P < 0.01), male sex (P < 0.05), and previous MI (P < 0.01) predicted CHD death (n = 45). NIDDM (P < 0.01), male sex (P < 0.05), previous MI (P < 0.05), current smoking (P < 0.001), systolic blood pressure (P < 0.001), and low high-density lipoprotein cholesterol (P < 0.01) predicted all CHD events (CHD death or nonfatal MI) (n = 107). In NIDDM subjects, only glycated hemoglobin A1c (GHbA1c) at baseline (P < 0.01) and duration of diabetes (P < 0.05) predicted CHD death (n = 15) and all CHD events (n = 33). There was a significant increase in the risk of CHD death and all CHD events in NIDDM subjects with GHbA1c levels higher than 7.0% compared with diabetic subjects with lower GHbA1c (ORs 4.3 [1.1-16.7] and 2.2 [1.0-5.1]). In conclusion, NIDDM and its metabolic control and the duration of diabetes are important predictors of CHD in elderly subjects, particularly in women.

Non-insulin-dependent diabetes and its metabolic control are important predictors of stroke in elderly subjects

BACKGROUND AND PURPOSE

Non-insulin-dependent diabetes mellitus (NIDDM) is a major risk factor for stroke in the middle-aged population, but few prospective population-based studies are available in the elderly. Moreover, the importance of metabolic control and the duration of diabetes in diabetic subjects has remained controversial. There are no previous studies on association of insulin with the risk of stroke. The present study examined whether NIDDM, its metabolic control and duration, and insulin level predict stroke.

METHODS

We measured cardiovascular risk factors including glucose tolerance, plasma insulin, and glycosylated hemoglobin A1c in a Finnish cohort of 1298 subjects aged 65 to 74 years and investigated the impact of these risk factors on the incidence of both fatal and nonfatal stroke during 3.5 years of follow-up.

RESULTS

Of 1298 subjects participating in the baseline study, 1069 did not have diabetes and 229 had NIDDM. During the 3.5-year follow-up, 3.4% (n = 36) of nondiabetic subjects and 6.1% (n = 14) of NIDDM subjects had a nonfatal or fatal stroke. The incidence of stroke was significantly higher in diabetic women compared with nondiabetic women (odds ratio [OR], 2.25; 95% confidence interval [CI], 1.65 to 3.06). In contrast, the risk of stroke was not significantly higher in diabetic men than in nondiabetic men (OR, 1.36; 95% CI, 0.44 to 4.18). In multivariate logistic regression analyses including all study subjects, fasting and 2-hour glucose (P < .01 and P < .05, respectively), glycosylated hemoglobin A1c (P < .01), atrial fibrillation (P < .05), hypertension (P < .05), and previous stroke (P < .01) predicted stroke events. In diabetic subjects, fasting and 2-hour glucose (P < .01 and P < .05, respectively), glycosylated hemoglobin A1c (P < .05), the duration of diabetes (P < .05), and atrial fibrillation (P < .05) were the baseline variables predicting stroke events. Finally, fasting insulin (P < .05), hypertension (P < .05), and previous stroke (P < .01) were associated with stroke incidence in nondiabetic subjects.

CONCLUSIONS

Our 3.5-year follow-up study provides evidence that NIDDM, its metabolic control, and the duration of diabetes are important predictors of stroke in elderly subjects, particularly in women. Moreover, fasting insulin level appears to be a risk factor for stroke in elderly nondiabetic subjects.

Microalbuminuria precedes the development of NIDDM

Several studies have indicated that insulin resistance, elevated blood pressure (BP), and dyslipidemia precede the onset of non-insulin-dependent diabetes mellitus (NIDDM). Little data, however, exist on the presence of renal disease in prediabetic subjects. We measured albumin excretion in a cross-sectional population study in subjects 65-74 years of age living in eastern Finland in relation to the risk of developing diabetes 3.5 years later. The prevalence of microalbuminuria (urinary albumin-to-urinary creatinine ratio > or = 2 mg/mmol) was 1.3-, 1.8-, and 2.0-fold higher among subjects with impaired glucose tolerance (n = 242), newly diagnosed NIDDM subjects (n = 92), and previously diagnosed NIDDM subjects (n = 136), respectively, compared with subjects with normal glucose tolerance (n = 826). Nondiabetic subjects with microalbuminuria had multiple abnormalities in cardiovascular risk factors including elevated BP, high triglyceride concentration, high insulin concentration, and a low high-density lipoprotein cholesterol concentration, a cluster of risk factors typical for prediabetic individuals. The relationship between microalbuminuria and the incidence of NIDDM over the 3.5-year follow-up was studied in 891 subjects who were free of diabetes at baseline. Converters to diabetes (n = 69) had a higher prevalence of hypertension (68.1 vs. 54.4%, P < 0.05) and a higher prevalence of microalbuminuria (43.5 vs. 30.4%, P < 0.05) than nonconverters (n = 822). In logistic regression analysis, microalbuminuria predicted the development of NIDDM independently of BP level.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperinsulinemia predicts multiple atherogenic changes in lipoproteins in elderly subjects

Several studies have shown that hyperinsulinemia and insulin resistance are associated with high triglyceride and low high-density lipoprotein (HDL) cholesterol levels. However, previous studies have been cross-sectional, and thus the presence of hyperinsulinemia or insulin resistance could be a consequence of the underlying lipid disorder instead of its cause. Therefore, we examined the relation of fasting insulin level measured in a cross-sectional study in nondiabetic subjects 65 to 74 years old (n = 881) to the risk of developing lipid disorders 3.5 years later. The incidence of the following lipid abnormalities was calculated: hypertriglyceridemia (n = 49/732, incident cases/subjects free of the particular disorder at baseline), high low-density lipoprotein (LDL) cholesterol level (n = 43/696), low HDL cholesterol level (n = 33/708), high apolipoprotein (apo) B level (n = 72/699), low apoAI level (n = 47/711), low serum LDL cholesterol/serum apoB ratio (n = 55/685), and low serum HDL cholesterol/serum apoAI ratio (n = 48/707). Baseline insulin level was not significantly associated with the development of high LDL cholesterol or low HDL cholesterol levels. Baseline insulin was associated with the development of hypertriglyceridemia (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.12 to 2.40; P = .011), high apoB (OR, 1.54; 95% CI, 1.13 to 2.10; P = .006), low apoAI (OR, 1.72; 95% CI, 1.22 to 2.42; P = .002), low LDL cholesterol/apoB ratio (OR, 1.99; 95% CI, 1.36 to 2.90; P < .001), and low HDL cholesterol/apoAI ratio (OR, 1.93; 95% CI, 1.34 to 2.79; P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Essential hypertension and cognitive function. The role of hyperinsulinemia

The relation between hypertension and cognitive function is not well established. Therefore, we examined cognitive function in a random sample of 744 nondiabetic elderly inhabitants of Kuopio, East Finland. Five brief neuropsychological tests known to be sensitive to cognitive impairment due to dementia--the Mini-Mental State Examination (MMSE), the Trail Making Test (TMT), the Buschke Selective Reminding Test (BSR), Russell's Adaptation of the Visual Reproduction Test (HVR), and the Verbal Fluency Test (VFT)--were used to evaluate cognitive function. The performance of the hypertensive group (n = 378) was impaired in almost all test items compared with that of the normotensive group (n = 366), but the difference between these two groups was statistically significant in 5 of 19 test items only. Moreover, within the hypertensive group, hyperinsulinemic (fasting plasma insulin > 17.9 mU/L) hypertensive subjects (n = 57) scored worse than normoinsulinemic hypertensive subjects (n = 321) in 16 of 19 test items and worse than the normotensive subjects in the same 16 of 19 test items. The difference between the hyperinsulinemic hypertensive and normotensive groups was significant in 11 test items that reflected complex cognitive function such as calculation, language, semantic memory, and problem solving. This difference in neuropsychological tests among the three study groups (normotensive, normoinsulinemic hypertensive, and hyperinsulinemic hypertensive subjects) persisted after adjustment for fasting plasma glucose, age, sex, and education in 3 test items measuring calculation, copying, and semantic memory. Thus, essential hypertension in the elderly is associated with an impairment in complex cognitive function.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular disease risk factors as predictors of type 2 (non-insulin-dependent) diabetes mellitus in elderly subjects

Risk factors measured in a cross-sectional study in subjects aged 65-74 years living in eastern Finland were correlated with the risk of developing diabetes 3.5 years later. Sixty-nine of 892 initially non-diabetic subjects developed diabetes during the follow-up. Subjects who subsequently developed diabetes had multiple adverse changes in risk factor levels before the diagnosis of diabetes. Subjects who developed diabetes had higher body mass index and waist-hip ratio as well as higher levels of fasting and 2-h plasma glucose and insulin and higher prevalence of family history of diabetes than those who remained healthy. Furthermore, prevalence of hypertension and levels of diastolic blood pressure and total triglycerides were higher and HDL cholesterol lower among subjects who developed diabetes than among those who remained healthy. The highest risk of developing diabetes was associated with impaired glucose tolerance (World Health Organisation criteria) (odds ratio = 9.8, 95% confidence interval = 6.1-5.8). The risk of developing diabetes was 3.7 (3.2-6.1) among subjects in the highest quartile of 2-h insulin distribution, 3.5 (2.0-6.1) in those with triglycerides greater than 2.5 mmol/l, 2.7 (1.5-4.6) in those with waist-hip ratio greater than 1.0, 2.5 (1.5-4.4) in those with HDL cholesterol less than 1.0 mmol/l, 2.1 (1.2-3.6) in those with body mass index greater than 30 kg/m2, 1.9 (1.1-3.3) among those in the highest quartile of fasting insulin distribution, 1.8 (1.0-3.1) in those having hypertension, and 1.7 (1.0-2.9) in those with a family history of diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)