The calcium-activated chloride channel-associated protein rCLCA2 is expressed throughout rat epidermis, facilitates apoptosis and is downmodulated by UVB.

The rodent chloride channel regulatory proteins mCLCA2 and its porcine and human homologues pCLCA2 and hCLCA2 are expressed in keratinocytes but their localization and significance in the epidermis have remained elusive. hCLCA2 regulates cancer cell migration, invasion and apoptosis, and its loss predicts poor prognosis in many tumors. Here, we studied the influences of epidermal maturation and UV-irradiation (UVR) on rCLCA2 (previous rCLCA5) expression in cultured rat epidermal keratinocytes (REK) and correlated the results with mCLCA2 expression in mouse skin in vivo. Furthermore, we explored the influence of rCLCA2 silencing on UVR-induced apoptosis. rClca2 mRNA was strongly expressed in REK cells, and its level in organotypic cultures remained unchanged during the epidermal maturation process from a single cell layer to fully differentiated, stratified cultures. Immunostaining confirmed its uniform localization throughout the epidermal layers in REK cultures and in rat skin. A single dose of UVR modestly downregulated rClca2 expression in organotypic REK cultures. The immunohistochemical staining showed that CLCA2 localized in basal and spinous layers also in mouse skin, and repeated UVR induced its partial loss. Interestingly, silencing of rCLCA2 reduced the number of apoptotic cells induced by UVR, suggesting that by facilitating apoptosis, CLCA2 may protect keratinocytes against the risk of malignancy posed by UVB-induced corrupt DNA.

Hyaluronan metabolism enhanced during epidermal differentiation is suppressed by vitamin C.

BACKGROUND: Hyaluronan is a large, linear glycosaminoglycan present throughout the narrow extracellular space of the vital epidermis. Increased hyaluronan metabolism takes place in epidermal hypertrophy, wound healing and cancer. Hyaluronan is produced by hyaluronan synthases and catabolized by hyaluronidases, reactive oxygen species and KIAA1199. OBJECTIVES: To investigate the changes in hyaluronan metabolism during epidermal stratification and maturation, and the impact of vitamin C on these events. METHODS: Hyaluronan synthesis and expression of the hyaluronan-related genes were analysed during epidermal maturation from a simple epithelium to a fully differentiated epidermis in organotypic cultures of rat epidermal keratinocytes using quantitative reverse transcriptase polymerase chain reaction, immunostaining and Western blotting, in the presence and absence of vitamin C. RESULTS: With epidermal stratification, both the production and the degradation of hyaluronan were enhanced, resulting in an increase of hyaluronan fragments of various sizes. While the mRNA levels of Has3 and KIAA1199 remained stable during the maturation, Has1, Has2 and Hyal2 showed a transient upregulation during stratification, Hyal1 transcription remained permanently increased and transcription of the hyaluronan receptor, Cd44, decreased. At maturation, vitamin C downregulated Has2, Hyal2 and Cd44, whereas it increased high-molecular-mass hyaluronan in the epidermis, and reduced small fragments in the medium, suggesting stabilization of epidermal hyaluronan. CONCLUSIONS: Epidermal stratification and maturation is associated with enhanced hyaluronan turnover, and release of large amounts of hyaluronan fragments. The high turnover is suppressed by vitamin C, which is suggested to enhance normal epidermal differentiation in part through its effect on hyaluronan.

rClca2 is associated with epidermal differentiation and is strongly downregulated by ultraviolet radiation.

BACKGROUND: Excessive skin exposure to solar radiation damages proteins and DNA, ultimately leading to skin ageing and cancers. OBJECTIVES: To identify new ultraviolet B (UVB) target genes to understand the mechanisms behind the detrimental effects of UVB. METHODS: Organotypic, stratified cultures of rat keratinocytes were exposed to UVB and analysed using a genome-wide expression array, quantitative real-time polymerase chain reaction and histology. The most downregulated gene, rClca2, was further characterized in rat keratinocytes and mouse skin models. RESULTS: A single, 30 mJ cm(-2) dose of broadband UVB proved effective in the organotypic epidermal culture. The expression of 627 genes was changed 24 h postirradiation. In silico analysis of the data indicated activation of DNA repair, metabolism, cell cycle control and amino acid metabolism, but only limited inflammation under these conditions. We selected for further investigation the most downregulated gene, rClca2, previously suggested to regulate keratinocyte differentiation and adhesion, and found that UVB caused a long-lasting downregulation in its expression. Both the rClca2 full-length isoform (expressed in the differentiating cells) and the truncated isoform (expressed in the basal layers) were reduced by UVB. Immunohistochemistry of mouse skin samples with isoform-specific antibodies showed a similar, epidermal differentiation-related pattern. In mouse specimens exposed to chronic ultraviolet radiation (UVR) the staining intensities were reduced and the differentiation-related isoform was disturbed in the hyperplastic and carcinomatous areas induced by UVR. CONCLUSIONS: The data show that rClca2 is a novel UVB target gene and suggest that it might play a role in epidermal differentiation and UV-dependent skin malignancies.

Genetic polymorphism of platelet glycoprotein IIIa in patients with acute myocardial infarction and acute ischaemic stroke.

BACKGROUND: It has recently been suggested that the Leu33Pro polymorphism of the platelet glycoprotein IIIa affects the risk of coronary thrombosis. Finland is genetically isolated and has an incidence of cardiovascular disease among the highest in the world. Interestingly, the prevalence of ischaemic heart disease also varies in different parts of the country, being highest in eastern Finland. METHOD: We studied the Leu33Pro polymorphism using polymerase chain reaction in 133 patients with coronary artery disease, 234 patients with cerebrovascular disease and 326 control subjects originating from two areas of Finland. RESULTS: The frequencies of the Pro33 allele in the patients with acute myocardial infarction and cerebrovascular attack were 13% and 14%, respectively, and did not differ from the controls (13%). Among patients with acute myocardial infarction from the Helsinki area, the family history of premature coronary artery disease was more often positive in carriers of the Pro33 allele than in non-carriers, but after adjustment for multiple comparisons the difference was no longer significant. CONCLUSIONS: We could not confirm the original observation that the Pro33 allele constitutes an independent risk factor for coronary artery disease. Further studies are needed to clarify whether co-occurrence of Pro33 and some unrecognized inherited factor pose an additional risk of vascular disease.

Visual versus computerized analysis of upsloping ST segment depression in the exercise electrocardiogram.

A slowly upsloping ST segment depression is an abnormal, and a rapidly upsloping ST segment depression is a normal exercise ECG response. We investigated the agreement of expert physicians on the visual classification of the ST segment depression, and compared the (majority) vote with the computer-generated ST slope. A total of 206 exercise ECG leads with an amplitude of the ST segment depression > or = 0.15 mV and a ST segment slope > or = 0.5 mVs(-1) were evaluated. All three interpreters agreed in 68 cases, two agreed in 123 cases, and all disagreed in 15 cases. Intraobserver agreement was 61%. The ST segment slope was significantly (p < 0.001) greater in leads generally interpreted as rapidly upsloping (n = 38; 2.1 +/- 0.8 mVs(-1)), than in those interpreted as slowly upsloping (n 121; 1.3 +/- 0.6 mVs(-1)) or horizontal (n = 32; 1.1 +/- 0.4 mVs(-1)), although there was some overlap. Thus, standardization of the computer-assisted exercise ECG interpretation should be continued.

Arg506Gln factor V mutation (factor V Leiden) in patients with ischaemic cerebrovascular disease and survivors of myocardial infarction.

The point mutation Arg506- > Gln of factor V was recently shown to be an important and relatively common genetic cause of venous thromboembolism. Using a DNA technique based on polymerase chain reaction, we surveyed the blood samples of 236 patients with ischaemic stroke or a transient ischaemic attack, 122 survivors of myocardial infarction and 137 control subjects for the presence of this mutation. Although the frequency of the factor V mutation in patients with arterial disease (4.5%) was not significantly different from that in healthy blood donors (2.9%), a carrier status for this mutant gene was associated with symptoms of migraine and relatively mild angiographic abnormalities among patients with cerebrovascular disease. A more extensive study addressing the occurrence and significance of the mutant factor V mutation in patients with vasospastic cerebrovascular diseases seems to be warranted.

Polymorphisms of the apolipoprotein and angiotensin converting enzyme genes in young North Karelian patients with coronary heart disease.

The genes encoding apolipoproteins (apos) A-I, B, C-III and E as well as that encoding the angiotensin converting enzyme (ACE) have been proposed as candidate genes for coronary heart disease (CHD). We determined the common polymorphisms of the apo genes, previously found to influence serum lipid levels at the population level, and the insertion/deletion polymorphism of the ACE gene, recently reported to reflect the risk of myocardial infarction, in 82 very young (mean, 41 years) North Karelian Finns with symptomatic CHD and 50 controls of similar age. Patients with familial hypercholesterolemia had been excluded from this material. None of the polymorphisms examined, including the apo A-I promoter MspI, apo C-III SstI and apo B XbaI restriction fragment polymorphisms, a common variation of apo E (epsilon 2, epsilon 3 and epsilon 4 alleles) and an ACE insertion/deletion (I/D) polymorphism, was significantly associated with the risk of premature CHD. Patients with CHD had a higher mean serum LDL cholesterol/HDL cholesterol ratio than controls (3.15 +/- 1.30 vs 2.72 +/- 0.98, P < 0.05), but no significant associations between the common apo gene polymorphisms and serum lipid levels were disclosed in either group. It is possible that other genetic loci than those proposed to be associated with accelerated atherosclerosis may be more important as risk factors of symptomatic CHD at the age of 40 years.

Prevalence of familial hypercholesterolemia among young north Karelian patients with coronary heart disease: a study based on diagnosis by polymerase chain reaction.

Two deletions of the low density lipoprotein (LDL) receptor gene account for about 90% of the mutations that cause familial hypercholesterolemia (FH) in eastern Finland. The FH-Helsinki mutation deletes exons 16, 17 and a portion of exon 18, while the FH-North Karelia allele is characterized by a deletion of seven nucleotides from exon 6 of the LDL receptor gene. We developed a DNA assay based on the use of polymerase chain reaction (PCR) which simultaneously detects both of these mutations. We have screened 90 young (< 45 years) eastern Finns with symptomatic coronary heart disease (CHD) for the presence of these FH genes. One or the other of the mutations was present in 4 out of 55 survivors of acute myocardial infarction (AMI) and 4 out of 35 patients with angina pectoris (AP), but in none of 50 healthy controls of similar age. These data show a relatively high prevalence of confirmed FH in young CHD patients (AMI and MI combined: 8/90, or 9%), and also demonstrate the feasibility of PCR techniques in diagnosis of FH among populations with enrichment of specific types of LDL receptor gene mutations.

Apolipoprotein E polymorphism determined by restriction enzyme analysis of DNA amplified by polymerase chain reaction: convenient alternative to phenotyping by isoelectric focusing.

Three common alleles determine six apolipoprotein E (apo E) phenotypes that are associated with variations in serum cholesterol in the population. This genetic variation results from single nucleotide alterations at two DNA loci encoding the amino acid residues 112 and 158 of apo E. We compared results of apo E phenotyping carried out by isoelectric focusing with those of apo E genotyping accomplished by direct DNA analysis. In the latter, the target DNA was amplified by the polymerase chain reaction (PCR) and subsequently analyzed by digestion with the restriction enzyme Hha I, followed by polyacrylamide gel electrophoresis of the cleavage products. With one exception, these two techniques yielded similar results from all 40 samples tested. In addition, a rare variant form of apo E (phenotype E1) was analyzed separately and incorrectly diagnosed as E2 by the Hha I digestion method; the anticipated mutation in the codon 127 was, however, confirmed by demonstration of a new Taq I restriction site in this variant gene. These data confirm that the common isoforms of apo E usually arise from genetic variation of the codons 112 and 158 and demonstrate the feasibility of the PCR technique in apo E genotyping.

Exercise capacity and hemodynamics in persons aged 20 to 50 years with systemic hypertension treated with diltiazem and atenolol.

Hemodynamic responses and exercise capacity were studied during maximal exercise in 25 young hypertensive persons (mean age 40 years) taking placebo, diltiazem (mean 216 mg/day) and atenolol (mean 80 mg/day). The study was a crossover, double-blind, randomized trial, each medication period lasting 2 months. Sitting blood pressure (BP) was 160 +/- 19/109 +/- 8 mm Hg after run-in. Both drugs decreased BP significantly, diltiazem by 10/ 11 mm Hg and atenolol by 16/14 mm Hg (difference not significant between drugs). During exercise there were no differences among patients taking placebo, diltiazem and atenolol in peak workload and rating of perceived exertion. Atenolol significantly attenuated the increase in heart rate, BP and heart rate-BP product at each workload. Diastolic BP during exercise was significantly lower (6 to 10 mm Hg) during diltiazem therapy than during placebo at each workload. Thus, both diltiazem and atenolol decrease rest BP significantly without impairing exercise capacity.

Synthesis and degradation of type I procollagen mRNAs in cultured human skin fibroblasts and the effect of cortisol.

The metabolism of type I procollagen mRNAs was studied in confluent cultures of human skin fibroblasts using the recombinant plasmids Hf677 and Hf32, which contain DNA sequences complementary to human pro-alpha 1(I) and pro-alpha 2(I) mRNAs, respectively. The ratio for the amount of pro-alpha 1(I) mRNAs to pro-alpha 2(I) mRNAs was 2.06:1. These mRNAs were labeled during in vitro transcription of isolated nuclei in the ratio 2.16:1 and during a pulse in cellulo in the ratio 1.96:1, suggesting that the two species are synthesized in the ratio 2:1. No significant differences were found in the rates of degradation, the half-lives of the pro-alpha 1(I) and pro-alpha 2(I) mRNAs being 9.2 and 8.4 h, respectively. Addition of 10 microM cortisol to the growth medium reduced the amounts of the type I procollagen mRNAs by half in 6 h, leaving their ratio unaltered. Incubation of the cells with cortisol had only minor effects on the subsequent synthesis of the mRNAs in isolated nuclei in vitro, whereas the degradation rates in cellulo were distinctly accelerated.

Modulation of glucocorticoid receptor activity by cyclic nucleotides and its implications on the regulation of human skin fibroblast growth and protein synthesis.

The modulation of glucocorticoid receptor activity by cyclic nucleotides was studied in cultured human skin fibroblasts. The receptors appeared to be activated in the presence of dibutyryl-cAMP and inactivated by dibutyryl-cGMP. Significantly, the cGMP content of the fibroblasts increased during cell growth, with a concomitant decrease in the glucocorticoid receptor activity, while when the cells reached early confluency the decrease in cGMP content was accompanied by an increase in cAMP and increased activity of the glucocorticoid receptors. In addition, cortisol induced (2'-5')oligoadenylate synthetase in these cells and raised the cellular (2'-5')oligoadenylate concentrations. This resulted in a decrease in both DNA and protein synthesis activity in the cells, a response which correlated with the (2'-5')oligoadenylate concentration. The combination of cortisol and dibutyryl-cAMP had a synergetic stimulatory effect on the (2'-5')oligoadenylate concentration and a synergetic inhibitory effect on protein synthesis. In conclusion, it is demonstrated here that cyclic nucleotides can modulate glucocorticoid receptor activity in cultured human skin fibroblasts, and thus these compounds may indirectly affect cellular metabolism by regulating the cellular responses to glucocorticoids.

Cortisol decreases the cellular concentration of translatable procollagen mRNA species in cultured human skin fibroblasts.

The effect of cortisol on the cellular concentration of translatable procollagen mRNAs was studied in cultured human skin fibroblasts. Cortisol selectively decreased the amount of procollagen mRNAs, in comparison to the total mRNA activity, when the cells were grown in enriched medium conditions, i.e., with 10% newborn calf serum. The selective decrease was first observed after 6 h exposure to 1 microM cortisol. In depleted medium conditions, i.e., with 2% newborn calf serum, the initial response was a stimulatory one, followed after about 12 h by a decrease in the procollagen mRNA activity. The results suggest that the selective inhibitory effect of cortisol on the cellular concentration of translatable procollagen mRNA species needs an optimal serum concentration. Furthermore, the results give support to the hypothesis that the decrease in the procollagen mRNA concentration after cortisol administration is a secondary response, preceded by the induction of some intracellular regulation system.