Carbonic anhydrase gene expression in CA II-deficient (Car2−/−) and CA IX-deficient (Car9−/−) mice

Using real-time PCR and immunohistochemistry, we have examined the expression of carbonic anhydrase isozymes (CA) I, II, III, IV, IX, XII, XIII and XIV in the brain, kidney, stomach and colon of the wild-type, CA II-deficient ( Car2^−/− ), and CA IX deficient ( Car9^−/− ) mice. The expression of Car4, Car12, Car13 and Car14 mRNAs did not show any significant deviations between the three groups of mice, whereas both groups of CA deficient mice showed decreased expression levels of Car1 in the colon and Car3 in the kidney. The Car2 mRNA level was greatly reduced but not completely abolished in all four tissues from the Car2^−/− mice in which no CA II protein was expressed. Sequencing the Car2 cDNA isolated from C57BL6 Car2^−/− mice revealed two nucleotide differences from the wild-type C57BL6 mice. One is a silent polymorphism found in Car2 mRNA from wild-type DBA mice, which is the strain that provided the original mutagenized chromosome. The second change is a mutation that causes prematurely terminated translation at codon 155 (Gln155X). Car9 mRNA and CA IX protein expression levels were up-regulated about 2.5- and 3.6-fold, respectively, in the stomach of the Car2^−/− mice. These results suggest that the loss of function of cytosolic CA II in the stomach of Car2^−/− mice leads to up-regulation of an extracellular CA, namely CA IX, which is expressed on the cell surface of the gastric epithelium.     

A mouse model for alpha-methylacyl-CoA racemase deficiency: adjustment of bile acid synthesis and intolerance to dietary methyl-branched lipids

alpha-Methylacyl-CoA racemase (Amacr) deficiency in humans leads to sensory motor neuronal and liver abnormalities. The disorder is recessively inherited and caused by mutations in the AMACR gene, which encodes Amacr, an enzyme presumed to be essential for bile acid synthesis and to participate in the degradation of methyl-branched fatty acids. To generate a model to study the pathophysiology in Amacr deficiency we inactivated the mouse Amacr gene. As per human Amacr deficiency, the Amacr(-/-) mice showed accumulation (44-fold) of C27 bile acid precursors and decreased (over 50%) primary (C24) bile acids in bile, serum and liver, however the Amacr(-/-) mice were clinically symptomless. Real-time quantitative PCR analysis showed that, among other responses, the level of mRNA for peroxisomal multifunctional enzyme type 1 (pMFE-1) was increased 3-fold in Amacr(-/-) mice. This enzyme can be placed, together with CYP3A11 and CYP46A1, to make an Amacr-independent pathway for the generation of C24 bile acids. Exposure of Amacr(-/-) mice to a diet supplemented with phytol, a source for branched-chain fatty acids, triggered the development of a disease state with liver manifestations, redefining the physiological significance of Amacr. Amacr is indispensable for the detoxification of dietary methyl-branched lipids and, although it contributes normally to bile acid synthesis from cholesterol, the putative pMFE-1-mediated cholesterol degradation can provide for generation of bile acids, allowing survival without Amacr. Based upon our mouse model, we propose elimination of phytol from the diet of patients suffering from Amacr deficiency.     

Immunohistochemical Study of Colorectal Tumors for Expression of a Novel Transmembrane Carbonic Anhydrase, MN/CA IX, with Potential Value as a Marker of Cell Proliferation

Carbonic anhydrase isoenzyme IX, MN/CA IX, is a recently discovered member of the carbonic anhydrase (CA) gene family with a suggested function in acid-base balance, intercellular communication, and cell proliferation. Increased expression of MN/CA IX has been observed with certain epithelial tumors. We investigated the expression of MN/CA IX in 69 colorectal neoplasms, consisting of 1 juvenile polyp, 8 hyperplastic polyps, 39 adenomatous lesions, 21 carcinomas, and 7 metastases. Tissue sections were immunostained with a monoclonal antibody specific to MN/CA IX. The proliferative activity of the tumor cells was evaluated by Ki-67 antigen immunoreactivity. The hyperplastic polyps showed a weak or moderate reaction for MN/CA IX only in the cryptal epithelium, as did the normal intestinal mucosa. The adenomas showed immunoreactivity mainly in the superficial part of the mucosa, whereas the distribution in the carcinomas and metastases was more diffuse. Comparative immunostaining of serial sections for Ki-67, a well established marker of cell proliferation, confirmed that MN/CA IX is expressed in areas with high proliferative capacity. Our results show abnormal MN/CA IX expression in colorectal neoplasms, suggesting its involvement in their pathogenesis. The co-occurrence of MN/CA IX and Ki-67 in the same tumor cells indicates its potential for use as a marker of increased proliferation in the colorectal mucosa.     

Factors related to postmenopausal muscle performance: a cross-sectional population-based study

The aim of the present study was to investigate cross-sectionally the association of postmenopausal muscle strength with simple performance tests. A random sample of 1,166 naturally postmenopausal women (born 1932–1941) was selected from the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study cohort. Grip and quadriceps strength were measured with strain gauge dynamometers and reported in both absolute values (KPa and kg) and per kilogram of body mass (N cm^–2 kg^–1 and N kg^–1). In addition, two performance tests, ability to stand on one foot and ability to squat down to touch the floor were carried out. A five-category self-assessment of overall health (very good, good, moderate, bad, and very bad) was obtained by postal questionnaire. The women that were able to stand on one foot and able to squat down to touch the floor had greater grip and quadriceps strength than their counterparts (P<0.001 and P<0.03 in ANOVA, respectively). In addition, self-assessed health had a strong positive association with muscle strength in the grip and leg extensor muscles in ANOVA (P<0.001 between very good and moderate or poorer state of health) and regression model (P<0.001). Adjustment for age, duration of menopause, body mass, height, physical activity level, use of HRT, and number of diseases and medications did not change any of the main effects. Also, there were no differences in results between absolute measurement values and values reported per kilogram of body mass. According to the present study, a simple performance test may be useful in the prediction of postmenopausal muscle strength. Furthermore, self-assessed state of health is strongly associated with muscle strength in postmenopausal women.     

Estrogen receptor genotype modulates myocardial perfusion in young men

Most of the effects of estrogens are mediated by estrogen receptors. Vascular endothelial cells and smooth muscle cells express estrogen receptor (ESR1) in both genders. A long genotype group of a common thymine-adenine (TA) dinucleotide repeat polymorphism in the regulatory region of this gene has previously been related to coronary artery disease. The present study examined whether coronary blood flow is affected by this genotype. A total of 49 healthy men were genotyped by PCR and divided into three groups according to median number of the ESR1 promoter TA repeat (=19), i.e., in the short allele genotype group both alleles were of fewer than 19 repeats whereas in the long allele group both alleles were 19 repeats or more. The intermediate group comprised men who had one short and one long allele. Myocardial blood flow was measured by positron emission tomography using [¹⁵O]water, performed at rest and during adenosine stimulation. Men with long alleles had lower adenosine-stimulated coronary flow than those with short alleles and those with one short and one long allelle. Our results suggest that adenosine-stimulated myocardial perfusion is lower in subjects with ESR1 long alleles than the other TA repeat genotypes.     

Heterogeneous expression of CD59 on human Purkinje cells

The expression of CD59 and other complement regulators was studied in human cerebellum from 14 individuals with no cerebellar pathology, from one patient with multiple sclerosis (MS) and from two patients with paraneoplastic cerebellar degeneration (PCD). CD59 was present on the Purkinje cells at various levels in eight of the 14 cases with no cerebellar pathology. CD59 was also present on the Purkinje cells of the patient with MS, but not on the scarce remaining Purkinje cells of the two patients with PCD. Other complement regulators (CD35, CD46 and CD55) were not expressed on the Purkinje cells, whereas CD59, CD46 and CD55 were present on the molecular, granulosa and endothelial cells. The results suggest that Purkinje cells not expressing CD59 could be especially prone to complement-mediated damage.     

Effect of Liposomal and Free Bisphosphonates on the IL-1β, IL-6 and TNFα Secretion from RAW 264 Cells in Vitro

Purpose. In order to evaluate the possible antiinflammatory action of bisphosphonates, the effect of the drugs on the secretion of proinflammatory cytokines (IL-l, IL-6 and TNF) from macrophages was studied. Liposomes or high concentration of extracellular calcium was used to enhance the intracellular delivery of bisphosphonates. Methods. RAW 264 cells were used as macrophage model, and they were induced with lipopolysaccharide to produce the cytokines. The cytokine concentrations in the culture supernatants were measured with time-resolved fluoroimmunoassay. Results. As a free drug, clodronate and pamidronate, but not etidronate, inhibited LPS-stimulated secretion of the cytokines from macrophage-like RAW 264 cells. Low concentrations of pamidronate, however, induced the IL-6 secretion, and the cytokine inhibitory action at the higher concentrations of pamidronate was attributed to cytotoxicity of the compound. The cytokine induction or toxic effects were not observed with clodronate or etidronate. When the drugs were encapsulated in negatively charged unilamellar liposomes, the inhibitory potency of both clodronate and etidronate enhanced by a factor of 10-20, while that of pamidronate was not increased. The complex formation of bisphosphonates with extracellular calcium, although enhancing the uptake of the compounds by macrophages, did not considerably increase their cytokine inhibitory potency. Conclusions. Bisphosphonates have inhibitory action on cytokine secretion by macrophages. The non-cytotoxic cytokine inhibition by liposome encapsulated clodronate could be beneficial in local inflammatory diseases, where the inflammation is sustained by the excessive amounts of inflammatory cytokines produced by activated macrophages.     

Alcohol reduces prefrontal cortical excitability in humans: a combined TMS and EEG study.

The effects of alcohol (0.8 g/kg) on the prefrontal cortex were studied in nine healthy subjects using the technique of transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG). A total of 120 magnetic pulses were delivered with a figure-of-eight coil to the left prefrontal cortex at the rate of 0.4-0.7 Hz. The EEG was recorded simultaneously with 60 scalp electrodes (41 electrodes were used for analysis); the TMS-evoked activation was estimated by the area under the global mean field amplitude (GMFA) time curve. TMS caused changes in EEG activity lasting up to 270 ms poststimulus. Alcohol decreased GMFA at 30-270 ms poststimulus (713+/-303 vs 478+/-142 microV ms; p=0.007). Alcohol-induced differences were most pronounced at anterior electrodes. These results suggest that alcohol reduces the excitability in the prefrontal cortex.