Single-Cell Proteomics Reveals the Defined Heterogeneity of Resident Macrophages in White Adipose Tissue

Adipose tissue macrophages (ATMs) regulate homeostasis and contribute to the metabolically harmful chronic inflammation in obese individuals. While evident heterogeneity of resident ATMs has been described previously, their phenotype, developmental origin, and functionality remain inconsistent. We analyzed white adipose tissue (WAT) during homeostasis and diet interventions using comprehensive and unbiased single-cell mass cytometry and genetic lineage tracking models. We now provide a uniform definition of individual subsets of resident ATMs. We show that in lean mice, WAT co-harbors eight kinetically evolving CD206⁺ macrophage subpopulations (defined by TIM4, CD163, and MHC II) and two CD206^- macrophage subpopulations. TIM4^-CD163⁺, TIM4^-CD163^- and CD206^- macrophage populations are largely bone marrow-derived, while the proliferating TIM4⁺CD163⁺ subpopulation is of embryonic origin. All macrophage subtypes are active in phagocytosis, endocytosis, and antigen processing in vitro, whereas TIM4⁺CD163⁺ cells are superior in scavenging in vivo. A high-fat diet induces massive infiltration of CD206^- macrophages and selective down-regulation of MHC II on TIM4⁺ macrophages. These changes are reversed by dietary intervention. Thus, the developmental origin and environment jointly regulate the functional malleability of resident ATMs.

Fetal-derived macrophages persist and sequentially maturate in ovaries after birth in mice

Macrophages, which are highly diverse in different tissues, play a complex and vital role in tissue development, homeostasis, and inflammation. The origin and heterogeneity of tissue-resident monocytes and macrophages in ovaries remains unknown. Here we identify three tissue-resident monocyte populations and five macrophage populations in the adult ovaries using high-dimensional single cell mass cytometry. Ontogenic analyses using cell fate mapping models and cell depletion experiments revealed the infiltration of ovaries by both yolk sac and fetal liver-derived macrophages already during the embryonic development. Moreover, we found that both embryonic and bone marrow-derived macrophages contribute to the distinct ovarian macrophage subpopulations in the adults. These assays also showed that fetal-derived MHC II-negative macrophages differentiate postnatally in the maturing ovary to MHC II-positive cells. Our analyses further unraveled that the developmentally distinct macrophage types share overlapping distribution and scavenging function in the ovaries under homeostatic conditions. In conclusion, we report here the first comprehensive analyses of ovarian monocytes and macrophages. In addition, we show that the mechanisms controlling monocyte immigration, the phenotype of different pools of interstitial macrophages, and the interconversion capacity of fetal-derived macrophages in ovaries are remarkably different from those seen in other tissue niches.

Hydroxysteroid (17β) dehydrogenase 1 expressed by Sertoli cells contributes to steroid synthesis and is required for male fertility

The pituitary gonadotrophins and testosterone are the main hormonal regulators of spermatogenesis, but estradiol is also known to play a role in the process. The hormonal responses in the testis are partially mediated by somatic Sertoli cells that provide nutritional and physical support for differentiating male germ cells. Hydroxysteroid (17β) dehydrogenase 1 (HSD17B1) is a steroidogenic enzyme that especially catalyzes the conversion of low potent 17keto-steroids to highly potent 17β-hydroxysteroids. In this study, we show that Hsd17b1 is highly expressed in Sertoli cells of fetal and newborn mice, and HSD17B1 knockout males present with disrupted spermatogenesis with major defects, particularly in the head shape of elongating spermatids. The cell-cell junctions between Sertoli cells and germ cells were disrupted in the HSD17B1 knockout mice. This resulted in complications in the orientation of elongating spermatids in the seminiferous epithelium, reduced sperm production, and morphologically abnormal spermatozoa. We also showed that the Sertoli cell-expressed HSD17B1 participates in testicular steroid synthesis, evidenced by a compensatory up-regulation of HSD17B3 in Leydig cells. These results revealed a novel role for HSD17B1 in the control of spermatogenesis and male fertility, and that Sertoli cells significantly contribute to steroid synthesis in the testis.-Hakkarainen, J., Zhang, F.-P., Jokela, H., Mayerhofer, A., Behr, R., Cisneros-Montalvo, S., Nurmio, M., Toppari, J., Ohlsson, C., Kotaja, N., Sipilä, P., Poutanen, M. Hydroxysteroid (17β) dehydrogenase 1 expressed by Sertoli cells contributes to steroid synthesis and is required for male fertility.

The diversity of sex steroid action: novel functions of hydroxysteroid (17β) dehydrogenases as revealed by genetically modified mouse models

Disturbed action of sex steroid hormones, i.e. androgens and estrogens, is involved in the pathogenesis of various severe diseases in humans. Interestingly, recent studies have provided data further supporting the hypothesis that the circulating hormone concentrations do not explain all physiological and pathological processes observed in hormone-dependent tissues, while the intratissue sex steroid concentrations are determined by the expression of steroid metabolising enzymes in the neighbouring cells (paracrine action) and/or by target cells themselves (intracrine action). This local sex steroid production is also a valuable treatment option for developing novel therapies against hormonal diseases. Hydroxysteroid (17β) dehydrogenases (HSD17Bs) compose a family of 14 enzymes that catalyse the conversion between the low-active 17-keto steroids and the highly active 17β-hydroxy steroids. The enzymes frequently expressed in sex steroid target tissues are, thus, potential drug targets in order to lower the local sex steroid concentrations. The present review summarises the recent data obtained for the role of HSD17B1, HSD17B2, HSD17B7 and HSD17B12 enzymes in various metabolic pathways and their physiological and pathophysiological roles as revealed by the recently generated genetically modified mouse models. Our data, together with that provided by others, show that, in addition to having a role in sex steroid metabolism, several of these HSD17B enzymes possess key roles in other metabolic processes: for example, HD17B7 is essential for cholesterol biosynthesis and HSD17B12 is involved in elongation of fatty acids. Additional studies in vitro and in vivo are to be carried out in order to fully define the metabolic role of the HSD17B enzymes and to evaluate their value as drug targets.

Inactivation of Palb2 gene leads to mesoderm differentiation defect and early embryonic lethality in mice

Mutations of the PALB2 tumor suppressor gene in humans are associated with hereditary predisposition to breast and also some other cancers. In the present study, we have characterized mice deficient in Palb2. The data show that the Palb2((+/-)) mice are normal and fertile, and lack macroscopic tumors when followed up till the age of 8 months. Homozygous (HO) Palb2((-/-)) mice present with embryonic lethality and die at E9.5 at the latest. The mutant embryos are smaller in size, developmentally retarded and display defective mesoderm differentiation after gastrulation. In Palb2((-/-)) embryos, the expression of cyclin-dependent kinase inhibitor p21 is increased, and Palb2((-/-)) blastocysts show a growth defect in vitro. Hence, the phenotype of the Palb2((-/-)) mice in many regards resembles those previously reported for Brca1 and Brca2 knockout mice. The similarity in the phenotypes between Palb2, Brca1 and Brca2 knockout mice further supports the functional relationship shown in vitro for these three proteins. Accordingly, our data in vivo suggest that a key function for PALB2 is to interact with and to build up appropriate communication between BRCA1 and BRCA2, thereby licensing the successful performance of the physiological tasks mediated by these two proteins, particularly in homologous recombination and in proper DNA damage response signaling.

Hydroxysteroid (17beta) dehydrogenase 7 activity is essential for fetal de novo cholesterol synthesis and for neuroectodermal survival and cardiovascular differentiation in early mouse embryos

Hydroxysteroid (17beta) dehydrogenase 7 (HSD17B7) has been shown to catalyze the conversion of both estrone to estradiol (17-ketosteroid reductase activity) and zymosterone to zymosterol (3-ketosteroid reductase activity involved in cholesterol biosynthesis) in vitro. To define the metabolic role of the enzyme in vivo, we generated knockout mice deficient in the enzyme activity (HSD17B7KO). The data showed that the lack of HSD17B7 results in a blockage in the de novo cholesterol biosynthesis in mouse embryos in vivo, and HSD17BKO embryos die at embryonic day (E) 10.5. Analysis of neural structures revealed a defect in the development of hemispheres of the front brain with an increased apoptosis in the neuronal tissues. Morphological defects in the cardiovascular system were also observed from E9.5 onward. Mesodermal, endodermal, and hematopoietic cells were all detected by the histological analysis of the visceral yolk sac, whereas no organized vessels were observed in the knockout yolk sac. Immunohistological staining for platelet endothelial cell adhesion molecule-1 indicated that the complexity of the vasculature also was reduced in the HSD17B7KO embryos, particularly in the head capillary plexus and branchial arches. At E8.5-9.5, the heart development and the looping of the heart appeared to be normal in the HSD17B7KO embryos. However, at E10.5 the heart was dilated, and the thickness of the cardiac muscle and pericardium in the HSD17B7KO embryos was markedly reduced, and immunohistochemical staining for GATA-4 revealed that HSD17B7KO embryos had a reduced number of myocardial cells. The septum of the atrium was also defected in the knockout mice.

Novel hydroxysteroid (17beta) dehydrogenase 1 inhibitors reverse estrogen-induced endometrial hyperplasia in transgenic mice

Local estrogen production plays a key role in proliferative endometrial disorders, such as endometrial hyperplasia and cancer. Hydroxysteroid (17beta) dehydrogenase 1 (HSD17B1) is an enzyme that catalyzes with high efficiency the conversion of weakly active estrone into highly potent estradiol. Here we report that female transgenic mice expressing human HSD17B1 invariably develop endometrial hyperplasia in adulthood. These mice also fail to ovulate and have enhanced peripheral conversion of estrone into estradiol in a variety of target tissues, including the uterus. As in humans, endometrial hyperplasia in HSD17B1 transgenic female mice was reversible on ovulation induction, which triggers a rise in circulating progesterone levels, and in response to exogenous progestins. Strikingly, a treatment with an HSD17B1 inhibitor failed to restore ovulation yet completely reversed the hyperplastic morphology of epithelial cells in the glandular compartment, although less so in the luminal epithelium. The data indicate that human HSD17B1 expression enhances endometrial estrogen production, and consequently, estrogen-dependent proliferation. Therefore, HSD17B1 is a promising new therapeutic target in the management of estrogen-dependent endometrial diseases.

Relation of myeloperoxidase promoter polymorphism and long‐term hormone replacement therapy to oxidized low‐density lipoprotein autoantibodies in postmenopausal women

OBJECTIVE

The myeloperoxidase enzyme (MPO) is a potent precursor of low-density lipoprotein (LDL) oxidation in atherosclerotic lesions. The MPO gene has a promoter polymorphism, 463G/A, which leads to high (GG) and low-expression (AG, AA) genotypes. Hormone replacement therapy (HRT) is known to affect MPO activity and LDL oxidation. The purpose of this study was to test whether the effect of HRT on the levels of oxLDL-ab varies according to MPO genotype.

MATERIAL AND METHODS

Eighty-seven postmenopausal women aged 45-71 years were divided into three groups based on the use of HRT. The HRT-EVP group (n = 25) used sequential estradiol valerate (EV) plus progestin, the HRT-EV group (n = 32) used EV alone, and the control group (n = 30) no HRT. MPO genotypes were determined by polymerase chain reaction (PCR) and oxLDL-ab by ELISA.

RESULTS

We found a significant HRT group by MPO genotype interaction (p = 0.021) in plasma oxLDL-ab levels. In subjects with the GG genotype, the oxLDL-ab titer increased in the order of 2.13 in controls, 2.53 in the EV group and 3.21 in the EVP group (ANOVA for trend p = 0.006).

CONCLUSIONS

The effects of HRT on LDL oxidation can vary according to MPO genotype and the concurrent progestin therapy with EV may counteract the more neutral effect of EV on LDL oxidation in subjects with the MPO high-expression genotype.

Fibrinogen: a comparison of an immunoturbidimetric method with four conventional methods

A rapid and simple immunochemical method for fibrinogen determination is described. The method is based on measuring the turbidity caused by antigen-antibody complexes with an enzyme analyser using diluted antiserum as a starting reagent. This immunoturbidimetric method correlates well with the immunodiffusion method and with two of the thrombin methods. Its correlation with the precipitation method according to Low was a little weaker.

HDL enhances oxidation of LDL in vitro in both men and women

Background

Oxidative modification of low-density lipoprotein (LDL) is a key event in the oxidation hypothesis of atherogenesis. Some in vitro experiments have previously suggested that high-density lipoprotein (HDL) co-incubated with LDL prevents Cu²⁺-induced oxidation of LDL, while some other studies have observed an opposite effect. To comprehensively clarify the role of HDL in this context, we isolated LDL, HDL₂ and HDL₃ from sera of 61 free-living individuals (33 women and 28 men).

Results

When the isolated LDL was subjected to Cu²⁺-induced oxidation, both HDL₂ and HDL₃ particles increased the rate of appearance and the final concentration of conjugated dienes similarly in both genders. Oxidation rate was positively associated with polyunsaturated fatty acid content of the lipoproteins in that it was positively related to the content of linoleate and negatively related to oleate. More saturated fats thus protected the lipoproteins from damage.

Conclusion

We conclude that in vitro HDL does not protect LDL from oxidation, but is in fact oxidized fastest of all lipoproteins due to its fatty acid composition, which is oxidation promoting.

Apolipoprotein E and A-IV polymorphisms in ethnic Russians living in Estonia

137 Russians living in Estonia was screened by isoelectric focusing and immunoblotting procedures to determine the distribution of genetic variations in apolipoprotein E (apoE) and apolipoprotein A-IV (apoA-IV) genes. The apoA-IV-2 allele and epsilon4 allele frequency of the Russians tended to be lower than in most other European populations.

High oxidized LDL and elevated plasma homocysteine contribute to the early reduction of myocardial flow reserve in healthy adults

BACKGROUND

Impairment of coronary blood flow reserve has been shown to be an early manifestation of atherosclerosis and coronary artery disease (CAD). We studied more closely the contribution of various risk factors on early deterioration of coronary function.

MATERIALS AND METHODS

Fifty-one young, apparently healthy adults, with normal or mildly elevated serum cholesterol levels but without other major risk factors for CAD, such as diabetes or hypertension, underwent positron emission tomography (PET) studies. Coronary flow reserve (CFR) was measured using O15-water. In addition to the classical risk factors, the role of several new risk indicators, such as low-density lipoprotein (LDL) oxidation, infection (Chlamydia pneumoniae antibodies), and inflammation parameters (adhesion molecules, ICAM, VCAM, selectin, and C-reactive protein), homocysteine and body iron stores were investigated.

RESULTS

Elevated lipid and lipoprotein levels were not associated with reduced coronary reactivity. However, high autoantibody titers against oxidized LDL (oxLDL) were associated with 21% lower CFR than low oxLDL (P < 0.05). Furthermore, high homocysteine levels predicted low CFR (P < 0.05). The other measured parameters, Chlamydia pneumoniae antibody levels, C-reactive protein and adhesion molecule concentrations did not associate with myocardial blood flow. In a stepwise regression model, oxLDL (P = 0.03), homocysteine (P = 0.04) and triglycerides (P = 0.018) were significant predictors of CFR.

CONCLUSIONS

The present study suggests an important role for oxidized LDL and plasma homocysteine on early impairment of coronary reactivity in young adults.

The relation of oxidized LDL autoantibodies and long-term hormone replacement therapy to ultrasonographically assessed atherosclerotic plaque quantity and severity in postmenopausal women

BACKGROUND

In epidemiologic studies, the incidence of atherosclerosis rises soon after menopause in women, and hormone replacement therapy (HRT) has proved to be useful in preventing onset of clinical manifestations of the disease. However, it is not known how HRT affects sonographically determined atherosclerotic severity (AS) and number of atherosclerotic plaques (NAP) in large arteries. Furthermore, it is not clear how HRT affects oxidation of low density lipoproteins (LDL), which obviously has an important role in the pathogenesis of atherosclerosis.

OBJECTIVES

The purpose of the study was to determine whether HRT has a beneficial effect on sonographically determined AS and NAP in large arteries of 101 postmenopausal women compared to 40 controls without HRT. We also studied the interaction of HRT and antibodies against oxidized LDL on AS and NAP progression.

RESULTS

Estradiol valerate alone, combined estradiol valerate-levonorgestrel and combined estradiol valerate-medroxyprogesterone acetate therapy are each associated with lower NAP and AS as compared to controls without HRT. In a multiple regression model explaining NAP in the whole study population, the strongest predictors were HRT (P=0.0006) and copper-oxidized LDL cholesterol autoantibodies (P=0.0491).

DISCUSSION

Our findings indicate that postmenopausal HRT is associated with a lower total number of atherosclerotic plaques and less severe atherosclerotic lesions, as compared to controls without HRT, and that this outcome may be associated with the effect of HRT on LDL cholesterol oxidation.

Paraoxonase gene polymorphisms and coronary reactivity in young healthy men

This study examined the relationships between paraoxonase genotypes, coronary artery reactivity, and indices of low-density lipoprotein oxidation in healthy men. Impairment in coronary flow reserve, as assessed by positron emission tomography, is associated with lipoprotein oxidation, which is affected by high-density lipoprotein bound enzyme, paraoxonase. Paraoxonase has two common polymorphisms (M/L55 and R/Q192) that change the activity of the enzyme. Forty-nine healthy men (mean age 35 +/- 4 years) were divided by paraoxonase genotype into low (Q192/Q192, or M55/M55, M55/L55) and high-active (R192/Q192, R192/R192, or L55/L55) groups and related to the myocardial blood flow, to the susceptibility of low-density lipoprotein to oxidation, and the autoantibody titer against oxidized low-density lipoprotein. The blood flow was measured by positron emission tomography at rest and during adenosine infusion. The low-active Q192/Q192 genotype was associated with higher resting blood flow corrected for rate-pressure product compared to the high-active R192/R192 and R192/Q192 genotypes (P=0.011). The blood flow stimulated by adenosine was not significantly different in the low- and high-active genotype groups. Paraoxonase genotypes had no effect on low-density lipoprotein susceptibility to oxidation or autoantibody formation against oxidized low-density lipoprotein. Genotypes of paraoxonase may not clearly contribute to the early changes in coronary reactivity. Coronary vasomotor tone at rest appears to be modulated by paraoxonase R/Q192 polymorphism through mechanism(s) unrelated to low-density lipoprotein oxidation.

Serum homocysteine does not associate with uncomplicated coronary heart disease

BACKGROUND

Elevated serum homocysteine concentrations have been related to coronary heart disease. However, the association has not indisputably been proven, and the mechanisms by which homocysteine may be atherogenic have only partially been elucidated. The objective of the present study was to investigate whether serum homocysteine is associated with angina pectoris and myocardial infarction.

METHODS

We compared serum homocysteine concentrations in subjects with clinical evidence of angina pectoris or history of myocardial infarction to age-matched controls. The study included 248 males, who participated in a large cross-sectional risk factor survey carried out in five geographic areas in Finland.

RESULTS

Serum homocysteine concentration was significantly higher in subjects with a history of myocardial infarction compared to controls (15.3 micromol L-1 and 13.9 micromol L-1 respectively, P = 0.037). In a logistic regression model including several cardiovascular risk factors, serum homocysteine was significantly associated with myocardial infarction (95% CI 1.0157-1.2990, P = 0.027). Serum homocysteine concentrations did not differ between subjects with angina pectoris and age-matched controls (13.9 micromol L-1 and 14.2 micromol L-1 respectively).

CONCLUSIONS

Our results suggest that elevated serum homocysteine is associated with myocardial infarction but not with uncomplicated coronary heart disease.

Lipid peroxidation is increased in paraoxonase L55 homozygotes compared with M-allele carriers

Human serum paraoxonase (PON) is an antioxidative enzyme, which circulates on high-density lipoproteins and appears to use oxidized phospholipids as physiological substrates. PON M/L55 substitution changes the ability of PON to prevent lipid oxidation. Urinary 8-iso-PGF(2alpha) (one of F2 -isoprostanes) may represent a non-invasive in vivo index of free radical generation and we propose that PON might influence the biosynthesis of 8-iso-PGF(2alpha) in the vasculature. We studied the urinary excretion of 8-iso-PGF(2alpha) and related it to PON M/L55 genotypes in patients with type 2 diabetes mellitus (n = 55) and non-diabetic control subjects (n = 55). Urinary 8-iso-PGF(2alpha) was determined by competitive ELISA and the PON genotype by a PCR based restriction enzyme digestion method. LL homozygotes were compared to M-allele carriers (ML heterozygotes and MM homozygotes). The urinary excretion of 8-iso-PGF(2alpha) among non-diabetic non-smoking LL homozygotes was 3995.5 +/- 3352.8 ng/24-hour and among M-allele carriers 1689.8 +/- 1051.3 ng/24-hour (p = 0.017, ANCOVA; gender, hypertension, total cholesterol, triglycerides and LDL cholesterol as covariates). The excretion of 8-iso-PGF(2alpha), was increased in type 2 diabetes mellitus compared to non-diabetic control subjects. PON may thus protect against oxidative stress by destroying some biologically active lipids. Excretion of 8-iso-PGF(2alpha) is increased in type 2 diabetes, which may reflect oxidant injury.

A comparison of serum trypsinogen-2 and trypsin-2-alpha1-antitrypsin complex with lipase and amylase in the diagnosis and assessment of severity in the early phase of acute pancreatitis

OBJECTIVE

The aim of the study was to compare the recently introduced laboratory markers trypsinogen-2 and trypsin-2-alpha1 antitrypsin complex (trypsin-2-AAT) in serum with lipase and amylase in the diagnostic and prognostic evaluation of patients with acute pancreatitis (AP).

METHODS

The analytes were measured on admission in 64 consecutive patients with AP and in 30 controls with acute abdominal disease of extrapancreatic origin. Twenty-one patients had severe and 43 mild AP. As reference methods we used serum amylase and C-reactive protein.

RESULTS

In subjects with AP, elevated trypsinogen-2 values (> or = 90 microg/L) were observed in 63 patients (98%), trypsin-2-AAT values (> or = 12 microg/L) in 64 patients (100%), lipase values (> or = 200 U/L) in 64 patients (100%), and amylase values (> or = 300 IU/L) in 62 patients (97%). The diagnostic accuracy of the markers was evaluated by receiver operating characteristic (ROC) analysis. On admission, trypsinogen-2, trypsin-2-AAT, lipase, and amylase differentiated patients with AP from controls with high accuracy and ROC analyses showed similar areas under the ROC curves (AUC) for trypsinogen-2 (AUC 0.960), trypsin-2-AAT (0.948), lipase (AUC 0.947), and amylase (AUC 0.930). For differentiation between severe and mild AP, trypsin-2-AAT (AUC 0.805) was slightly better than trypsinogen-2 (AUC 0.792), and they were both clearly better than lipase (AUC 0.583), C-reactive protein (AUC 0.519), or amylase (AUC 0.632) (p < 0.05).

CONCLUSIONS

All the markers studied showed high accuracy for differentiating between AP and extrapancreatic diseases. However, trypsinogen-2 and trypsin-2-AAT displayed the best accuracy for predicting a severe AP already at admission, which makes these markers superior for clinical purposes.

Alcohol consumption and its relation to lipid-based cardiovascular risk factors among middle-aged women: the role of HDL(3) cholesterol

To study the association of alcohol consumption and lipid-based cardiovascular risk factors among middle-age women, cross-sectional analysis among 274 middle-aged healthy women with different drinking habits and a follow-up analysis of alcoholic women during abstinence was performed. Serum total cholesterol, low and high-density lipoprotein cholesterol (LDL and HDL cholesterol), triglycerides (TG), apolipoproteins A1 (Apo A1) and B (Apo B), and HDL-cholesterol subfractions 2 (HDL(2)) and 3 (HDL(3)) were measured. All lipid values except LDL cholesterol positively correlated with self-reported alcohol consumption. When alcoholics were excluded the correlation was significant only for HDL cholesterol, HDL(3), and Apo A1. The increasing trend of HDL cholesterol, HDL(3) and Apo A1 were clearly seen first in women consuming >20-40 g/day of absolute alcohol. Alcohol consumption >40 g/day increased all lipid values except LDL cholesterol. Abstinence for 2 weeks caused a significant decrease in HDL(3) cholesterol, and an increase in LDL cholesterol and Apo B. The results indicate that among middle-aged women the Apo A1 and HDL cholesterol via its HDL(3) but not HDL(2) subfraction might play a role in the beneficial coronary consequences associated with moderate alcohol consumption. However, the increasing beneficial trend first appears when daily drinking exceeds 20 g/day.

Low trehalase activity is associated with abdominal symptoms caused by edible mushrooms

BACKGROUND

The purpose of the study was to evaluate whether maldigestion of trehalose causes abdominal symptoms and which available diagnostic method best distinguishes intolerant from tolerant subjects.

METHODS

A 25-g oral trehalose load test was performed in 64 subjects. The 19 experiencing clear symptoms constituted the trehalose-intolerant subjects. Changes from base-line levels of blood glucose, breath hydrogen, and methane and symptoms were recorded after the test. Trehalase activity was determined in serum and on a duodenal biopsy specimen obtained by endoscopy.

RESULTS

Intolerant subjects were best differentiated from tolerant subjects by changes in breath gases (hydrogen and methane) and duodenal trehalase to sucrase ratio. The change in breath gases correlated inversely with duodenal trehalase activity, duodenal trehalase to sucrase ratio, and plasma trehalase activity. The correlation between serum and duodenal trehalase activities was on the order of 0.6. Two subjects were found to have trehalase deficiency.

CONCLUSIONS

It is obvious that trehalose maldigestion can cause symptoms similar to those of lactose maldigestion and intolerance. Three factors control the genesis of symptoms: 1) the activity of small-bowel trehalase: if it is low, trehalose is maldigested and more trehalose is passed into the colon; 2) the maldigested trehalose, which causes osmotic water flow into the colon, resulting in loose stools and diarrhea; and 3) most importantly, the microflora of the colon, from which symptoms will arise if there are bacteria capable of producing gases from maldigested trehalose. If colonic bacteria cannot produce gases, then distention of the abdomen and intestinal gas expulsion as eructations and flatus will not occur.

Association between M/L55-polymorphism of paraoxonase enzyme and oxidative DNA damage in patients with type 2 diabetes mellitus and in control subjects

The paraoxonase enzyme (PON) gene polymorphism causes a change of methionine (M-allele) to leucine (L-allele). PON may reduce low density lipoprotein oxidation and prevent atherosclerosis. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a sensitive index of oxidative DNA damage. We have studied the association between the PON genotypes and the urinary excretion of 8-OHdG. The study population consisted of 93 Finnish type 2 diabetes patients and 106 non-diabetic control subjects. The 24-h excretion of 8-OHdG was significantly higher in diabetic patients than in control subjects (P < 0.001). In control subjects, the ratio of the 8-OHdG/glomerular filtration rate increased in order of genotype from MM to ML to LL (P < 0.0412). These results suggest that lipid peroxidation may have an effect on DNA oxidation.

Autoantibodies against oxidized low density lipoprotein in patients with angiographically verified coronary artery disease

Oxidation of low density lipoproteins (LDL) obviously plays an important role in the pathogenesis of atherosclerosis. The purpose of the study was to determine whether antibodies against oxidized LDL are associated with coronary artery disease (CAD). We determined the serum levels of antibodies against copper-oxidized LDL by enzyme-linked immunosorbent assay in 58 patients with angiographically verified CAD and 34 controls without CAD. The mean antibody level, expressed in optical density units, was significantly higher in patients than in controls (0.150+/-0.088 versus 0.094+/-0.054, respectively; P=0.00089). In logistic regression analysis, high antibody level against oxidized LDL was associated significantly with CAD (P=0.0114), independent of age (P=0.00137), gender (P=0.0021), body mass index (P=0.5947), triglyceride concentration (P=0.9813), and total cholesterol-high density lipoprotein (HDL) cholesterol (P=0.0080) group. Similar analysis in nondiabetic subjects (n=79) and in men only (n=75) showed analogous results, with only minor changes in P values. The antibody level against oxidized LDL differed significantly between nonsmokers and smokers in CAD patients (P<0.00197) but not in controls (P=NS). In addition, the antibody level against oxidized LDL differed significantly between nonsmokers and smokers in subjects with low HDL cholesterol (</=0.9 mmol/L) but not in subjects with high HDL cholesterol (>0.9 mmol/L). In conclusion, elevated levels of antibodies against oxidized LDL were associated with CAD. The data suggest that oxidized LDL plays a role in the pathogenesis of atherosclerosis and suggest a protective function for HDL against LDL oxidation.

Mutation C677T of methylenetetrahydrofolate reductase gene is not associated with coronary artery disease, but possibly with albuminuria, in type 2 diabetic patients

The missense mutation in the 677th nucleotide (C677T) of methylenetetrahydrofolate reductase gene causes substitution of valine (V) for alanine (A) resulting in three genotypes VV, VA and AA. The VV genotype causes hyperhomocysteinemia and may be a risk factor for coronary artery disease. We determined genotypes by polymerase chain reaction and subsequent restriction fragment length analysis and compared them in 84 patients with type 2 diabetes and in 115 non-diabetic subjects with and without coronary disease. Fractional urinary excretion rate of albumin was assessed by nephelometry. The VV, VA, and AA frequencies in the diabetic and in the control groups were 0.095, 0.357, 0.548 and 0.061, 0.417, 0.522, respectively (p = NS, diabetic vs. controls, chi2 test). Genotype frequencies did not differ in either diabetic or control subjects between those with or those without coronary disease (chi2 test). The fractional urinary excretion rate of albumin (mean +/-SD) in diabetic patients with the VV genotype i.e. 1.59 +/-0.71 was lower (Kruskall-Wallis test p = 0.002) than in the other genotypes i.e. VA 5.98 +/-9.75 and AA 3.75 +/-4.77, respectively (post-hoc Mann-Whitney test VV vs. VA p = 0.005 and VV vs. AA p = 0.054, respectively). We found that in patients with type 2 diabetes the methylenetetrahydrofolate reductase VV genotype was associated with a low urinary albumin excretion but not with coronary artery disease or diabetes per se.

Apolipoprotein A-IV polymorphism in Saami and Finns: frequency and effect on serum lipid levels

Apolipoprotein A-IV (apoA-IV) is a glycoprotein constituent of triglyceride-rich and high-density lipoproteins (HDL) and may thus play an important role in lipid metabolism. In Finland two common isoforms (A-IV-1 and A-IV-2) of apoA-IV have been found. The isoforms are the result of the G to T substitution in the third base of the codon 360 in the apoA-IV-2 allele of the apoA-IV gene. The purpose of the study was to determine the apoA-IV allele frequencies in the Saami and the Finns, and to relate the apoA-IV phenotypes to serum lipids. The sample was drawn in connection with a Reindeer Herders' Health Survey performed in northern Finland in 1989. The study group included 248 men with known ethnic origin, Saami and Finns, who lived in the area of the nine northernmost municipalities of Finland. ApoA-IV phenotypes from 71 Saami (both parents Saami) and 177 Finns (both parents Finns) were determined by isoelectric focusing and Western blotting. Serum lipids were determined enzymatically. ApoA-IV allele frequencies in the Saami and the Finns were for A-IV-1 0.894 vs 0.944 and for A-IV-2 0.106 vs 0.056, respectively (chi2-test, P < 0.05). The effect of the apoA-IV phenotype on serum HDL-cholesterol levels differed significantly between the Saami and the Finns (two-way ANCOVA, interaction between ethnicity and apoA-IV phenotype, P < 0.02). In the Saami, HDL-cholesterol levels were significantly higher in the apoA-IV-2/1 than in the apoA-IV-1/1 phenotypes (ANCOVA, P < 0.05). Mean total cholesterol, low-density lipoprotein (LDL)-cholesterol, apolipoprotein B, HDL-cholesterol and triglyceride levels did not differ statistically significantly between the Saami and the Finns. Yet, there was a trend in the Saami of having higher mean total cholesterol, LDL-cholesterol and apolipoprotein B levels than the Finns among the apoA-IV-2/1 phenotypes, while there was only a small difference in these parameters between the Saami and the Finns among the apoA-IV-1/1 phenotypes. In conclusion, the Saami have a higher frequency of the apoA-IV-2 allele than the Finns and most of the other studied populations.

The effect of short-term fasting, apolipoprotein E gene polymorphism, and sex on plasma lipids

The effect of 1 wk of supervised fasting on plasma lipid concentrations in subjects with different apolipoprotein E (apo E) phenotypes was studied in 58 healthy free-living volunteers. The participants consumed an 870-kJ(208 kcal)/d liquid diet containing fruit and berry juices, tea, and water. The decline in plasma total cholesterol during 1 wk of fasting was 0.46 mmol/L in women and 0.35 mmol/L in men. The decreases were significant in both women and men. The response patterns of plasma total cholesterol were not significantly different between the sexes. In men, the changes in plasma low-density-lipoprotein cholesterol during the fast differed significantly (P = 0.0181) between the apo E phenotypes, whereas in women there were no differences due to phenotype (P = 0.695). The magnitude of the change in plasma triacylglycerol during the fast was different between the sexes (P = 0.0099). The changes in plasma triacylglycerols differed significantly between apo E phenotype groups in men (P = 0.0295) but not in women (P = 0.0661). Statistical comparison between different apo E phenotypes was performed with and without the small apo E3,2+E2,2 group, with essentially similar results. During fasting, plasma high-density-lipoprotein cholesterol concentrations decreased slightly but not significantly. The study shows significant differences in the associations of apo E alleles and sex on plasma lipid responses during fasting and illustrates the importance of gene-diet interactions in the regulation of lipid metabolism in humans.

Impaired ovarian function and risk factors for atherosclerosis in premenopausal women

OBJECTIVES

The aim of the study was to obtain information on the possible relationship between impaired ovarian function and risk factors for cardiovascular disease.

MATERIAL AND METHODS

Serum lipid levels, plasma fibrinolytic potential and histological and biochemical changes in the intima of the uterine artery were investigated in premenopausal women with irregular menstrual cycles, and the results were compared with those from regularly menstruating women. In addition, the same parameters were studied in postmenopausal women on hormone replacement therapy (HRT) and in postmenopausal women who had never used HRT. In total 64 patients undergoing hysterectomy for benign reasons were included the study.

RESULTS

Plasma fibrinogen concentration was significantly higher in irregularly menstruating women as compared with women with regular cycles. In women with irregular cycles thickened or sclerotic arterial intima was a significantly more common finding as compared with regularly menstruating women. A significant positive correlation was observed between plasma fibrinogen concentration and intimal esterified cholesterol content in women with thickened or sclerotic uterine artery.

CONCLUSIONS

These data suggest an important role for normal ovarian function in the prevention of atherosclerosis.

Women have a larger and less atherogenic low density lipoprotein particle size than men

Some epidemiological studies have shown that serum total cholesterol increases with age. especially in women. On the other hand, the risk of coronary artery disease is smaller in women than in men. Earlier studies have shown that a small dense low density lipoprotein (LDL) is more atherogenic than a large LDL. We studied LDL size and apolipoprotein E (apo E) phenotypes in premenopausal and postmenopausal women and in men at the same age. In this study 342 subjects participating in a health screening study were examined. There were four subgroups: 40-year-old men (n = 85), 40-year-old women (n = 80), 70-year old men (n = 88) and 70-year-old women (n = 89). In the present study LDL size was larger (P < 0.01) in women (26.39 +/- 0.07 nm) than in men (25.95 +/- 0.07 nm). We found that LDL size correlated highly positively (r = 0.606; P < 0.001) with serum high density lipoprotein (HDL) concentration and inversely with serum triglyceride concentration (r = -0.627; P < 0.001). Measuring serum HDL cholesterol and triglycerides in health screening studies gives information indirectly about LDL size and its atherogenicity. Apo E phenotype was not significantly associated with serum triglycerides, but was associated with LDL size, LDL cholesterol, total cholesterol and HDL cholesterol. In our sample LDL size decreased and LDL cholesterol and total cholesterol increased according to the most prevalent apo E phenotypes in the order E2/3, E3/3, E3/4 and E4/4. Subjects with phenotype apo E4/4 had the smallest LDL size (25.70 +/- 0.19 nm), the highest total cholesterol (6.53 +/- 0.35 mmol/l) and the lowest HDL cholesterol values (1.28 +/- 0.04 mmol/l). We conclude that there was a significant interaction between sex and age in serum total cholesterol which was highest in older women. However, their LDL size was larger and their LDL is less atherogenic. Apo E phenotype had a significant influence on LDL size.

Apolipoprotein E polymorphism, serum lipids, myocardial infarction and severity of angiographically verified coronary artery disease in men and women

In several populations, the apolipoprotein E (apo E) allele epsilon 4 is associated with high concentration of plasma total and low density lipoprotein (LDL)-cholesterol and coronary artery disease (CAD). We determined the apo E phenotypes of 309 patients with angiographically verified CAD and 38 patients without CAD by isoelectric focusing and Western blotting. In men with CAD, the plasma total and LDL-cholesterol increased according to apo E phenotype in the following order: E3/2 < E3/3 < E4/3 < E4/4 (P = 0.03 for total cholesterol, P = 0.007 for LDL-cholesterol). In women, there was a similar trend (P = 0.22 for total cholesterol, P = 0.15 for LDL-cholesterol). The relative frequency of men with three vessel CAD increased (P = 0.43) together with LDL-cholesterol levels (P = 0.05) according to apo E phenotype E3/2, E3/3, E4/3, E4/4. Total and LDL-cholesterol levels were higher in patients with three vessel CAD than in patients with less serious types of CAD (P = 0.02 for total cholesterol, P = 0.007 for LDL-cholesterol). The relative frequency of patients with myocardial infarction increased according to apo E phenotype (P = 0.51). Both in men and women, there were no differences between apo E phenotypes in age at occurrence of the first myocardial infarction. The apo E allele frequencies of patients with CAD vs. without CAD were 2.3% vs. 1.3% for epsilon 2, 79.0% vs. 76.3% for epsilon 3 and 18.7% vs. 22.4% for epsilon 4. There were no statistically significant differences in apo E allele or phenotype frequencies between patients with CAD and without CAD or between patients with CAD and the general Finnish population. Our results support previous studies in suggesting that the apo E allele epsilon 4 is a risk factor for atherosclerosis, which affects plasma total and LDL-cholesterol. In addition, our results suggest that the apo E allele determines the severity of CAD.

Hormone replacement therapy and atherosclerosis

Atherosclerotic changes associated with long-term hormone replacement therapy (HRT) were evaluated in 20 postmenopausal women (mean age, 62.8 +/- 6.1 years). The duration of hormone therapy was 10.1 +/- 3.4 (SD) years. For 9 women the HRT was sequential estradiol valerate plus levonorgestrel, for 6 women estradiol valerate plus medroxyprogesterone acetate and for 5 women estradiol valerate alone. Examinations consisted of histologic and biochemical studies of the uterine artery and ultrasonographic examinations of carotid arteries, aorta and iliac arteries. The findings were compared with those in 20 postmenopausal women of similar age and with similar body mass indexes who had never received HRT. Additionally, the same examinations were performed on 10 premenopausal women (48.3 +/- 4.6 years). The uterine artery was histologically normal in all the premenopausal women studied. Among the postmenopausal women without HRT, a histologically normal uterine artery was found in 5% and in women on HRT in 55% of cases (P < .01). In medicolegal autopsies, atherosclerosis in the uterine artery correlated significantly with atherosclerosis in the coronary artery and aorta. The free cholesterol content of the intima media in premenopausal women was lower than in postmenopausal women without HRT. The percentage of linoleic acid in the intima was significantly lower and that of docosapentaenoic acid significantly higher in premenopausal women and in postmenopausal women on HRT than in postmenopausal women without HRT. In the ultrasonographic examination atherosclerosis in the carotid artery was less common in premenopausal women and in women on HRT than in postmenopausal women without HRT. In this material, histologic, biochemical and radiologic studies showed that HRT may be protective against atherosclerosis.

Relationship of alcohol consumption to changes in HDL-subfractions

Epidemiological studies have consistently shown an apparent protective effect of moderate alcohol consumption on coronary artery disease (CAD). This has been considered to be due to the rise in the high-density cholesterol lipoprotein (HDL-cholesterol). Since the response of the HDL-subfractions to moderate or heavy dose of alcohol is less clear, we now compared the high-density lipoprotein cholesterol status between groups consuming different amounts of alcohol. In this population-based survey serum total high-density lipoprotein cholesterol and its HDL2 and HDL3 subfractions were blindly compared between 264 consecutive middle-aged men (37 teetotallers, 137 moderate drinkers, 90 heavy drinkers) participating in a voluntary health screening and 104 male alcoholics. Alcohol consumption correlated significantly (P < 0.001) with total HDL-cholesterol, HDL2, HDL3 when all subjects (n = 368) were included but the correlation disappeared when alcoholics were excluded (n = 264). In comparison with teetotallers, alcoholics had significantly higher total HDL-cholesterol, HDL2 and HDL3 values (P < 0.001). Moderate or heavy intake of alcohol had no effect on HDL2 but increased the HDL3-fraction. If the protective effect of moderate alcohol consumption is mediated by high-density lipoprotein, it may not be accounted for by changes in the HDL2-fraction. The observed increases in the concentration of the HDL3-fraction, however, suggest that this subfraction may not be inert with respect to coronary disease and could possibly have a role in the protective effect.

Apolipoprotein E phenotypes and plasma lipids in diabetic children and adolescents

Apolipoprotein E (apoE) polymorphism is a genetic determinant of serum lipoprotein levels and coronary heart disease risk. ApoE appears in three major isoforms E2, E3 and E4, coded by corresponding alleles epsilon 2, epsilon 3 and epsilon 4. These give six different phenotypes. Patients with insulin dependent diabetes (IDDM) have been reported to have increased incidence of E2/2 homozygosity. We studied the frequencies of apoE phenotypes and their association with plasma lipids in 201 diabetic children, aged 2-17 years, and in 216 healthy controls with the same age range. Phenotyping was performed directly from plasma by iso-electric focusing and immunoblotting. Plasma total and high density lipoprotein (HDL) cholesterol (C) and triglycerides were determined by routine laboratory methods. Apolipoprotein A1 (apoA1) and B (apoB) were measured by turbidometry. There were no differences in apoE phenotype or allele distributions between the diabetic and control subjects. The frequencies of epsilon 2, epsilon 3, and epsilon 4 in the diabetic and control children were 0.08 versus 0.07, 0.73 versus 0.72 and 0.19 versus 0.21. The difference in apoE2/2 frequencies (2.0 in diabetic and 0.5% in normal children) was not statistically significant. In the diabetic children, there was a distinct relation between apoE phenotype and plasma lipids; presence of apoE2 was associated with the lowest and that of apoE4 with the highest concentrations of total and low density lipoprotein (LDL) C, and apoB. Ratios of HDL-C/LDL-C and apoA1/apoB showed on opposite trend. The influence of apoE polymorphism on plasma lipids was less clear in the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of creatinine in serum and urine by cation-exchange high-pressure liquid chromatography

We describe an HPLC method for quantifying creatinine, separating the analyte from other compounds in serum and urine by cation-exchange chromatography and measuring its absorbance at 234 nm. The precision of the method (CV) varied from 2.9% (mean creatinine concentration, 31 mumol/L) to 1.7% (361 mumol/L) within a series of assays and from 3.9% (34 mumol/L) to 2.4% (391 mumol/L) between series. A comparison with the Jaffé method, as performed with a Technicon SMA analyzer, gave the regression line yHPLC = 1.00xJaffé - 12.0 (n = 141, r = 0.998, and Syx = 19). Results also are comparable with those of an enzymatic method, if the enzymatic method is standardized with a serum-based standard when serum samples are measured. An aqueous standard has to be used for enzymatic determination of creatinine in urine.

Late carotid restenosis: aetiologic factors for recurrent carotid artery stenosis during long-term follow-up

During a fourteen-year-period 257 patients underwent carotid endarterectomy in an unselected population of 700,000 inhabitants. The incidence of haemodynamically significant restenosis was 13.5% in 133 vessels in 116 patients studied by duplex scanning 28 to 209 months following carotid endarterectomy. The most striking differences between patent and restenosed cases were in serum cholesterol, triglyceride and HDL-cholesterol levels. The patients with a long-term low cholesterol (less than 6.5 mmol/l), low triglyceride (less than 1.42 mmol/l) and high HDL cholesterol (greater than 1.0 mmol/l) levels had significantly less high grade restenosis (P less than 0.05). Apolipoprotein A-I and B had no significant effect, but if the lowest limit of normal apolipoprotein A-I level was considered as 1.27 g/l the difference was significant. The frequency of a high-grade restenosis in patients with diabetes mellitus and coronary heart disease was not significantly increased, but supports the view that these are risk factors in the development of atherosclerotic changes in an operated carotid artery. The incidence of recurrent stenosis appears to be unrelated to hypertension, claudication, obesity, smoking, operative factors or to the indication for surgery. Men were more prone than women to get a high-grade restenosis. Postoperative treatment with acetylsalicylic acid was most effective, the incidence was only half of that expected, whereas the anticoagulants or a combination of acetylsalicylic acid and dipyridamole were of no benefit. Haematocrit, RBC, platelet count and thrombocrit were contradictory.

Urinary citrate excretion in patients with urolithiasis and normal subjects

Citrate is a normal constituent of urine which combines with calcium to form a soluble salt. Urinary citrate excretion was examined in patients with urolithiasis and normal subjects by a specific enzymatic technique. There was a considerable overlap in the urinary citrate excretion between normal subjects and stone-formers, but the citrate-creatinine ratio, the citrate-calcium ratio and the citrate-magnesium-calcium ratio, which were all highly significantly lower (p less than 0.001) in stone-formers than in controls, proved most reliable in discriminating between these groups.

Comparison of indirect diagnostic methods for hypolactasia

The aim of this study was to continue our previously published work and to compare the different indirect diagnostic methods for hypolactasia with the lactase to sucrase ratio obtained by jejunal biopsy. The following tests were performed in 63 adult patients: the breath hydrogen test, the lactose tolerance test with ethanol (serum galactose measurement after oral lactose load with ethanol), the urinary lactose tolerance test (urinary galactose measurement after oral lactose load with ethanol), and the strip test (like the former but using a special test strip for urinary galactose). Specificities of all these tests were good (96-98%). The 3-h breath hydrogen test was less sensitive (69%) than the other methods (81-94%). The strip test is recommended for the general practitioner for the diagnosis of this common cause of abdominal complaints.

Serum lipids in Finnish and Japanese postmenopausal women

Serum lipids were measured in 30 Finnish and Japanese postmenopausal women. Total cholesterol, HDL cholesterol, LDL cholesterol, apo B and the HDL cholesterol/apo A1 ratio were higher in Finnish than in Japanese women. The LDL cholesterol/apo B and apo A1/apo B ratios were lower in Finns than in Japanese. In serum phospholipids the percentage of arachidonic acid was higher and the percentage of the n - 3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, and the eicosapentaenoic acid/arachidonic acid ratio were lower in Finnish than in Japanese women. No significant correlations were found between serum oestrone levels and lipid parameters.