Increased bilirubin levels in de novo Parkinson's disease.

BACKGROUND AND PURPOSE: Oxidative stress is a central pathogenic mechanism of Parkinson's disease (PD), and the heme oxygenase (HO) bilirubin pathway is one of the main mammalian antioxidative defences. Indeed, there is growing evidence of HO-bilirubin upregulation from early phases of PD. Our aim was to investigate bilirubin as a possible biomarker of PD diagnosis and progression. METHODS: A cross-sectional case-control study was performed to evaluate differences in bilirubin levels between newly diagnosed, drug-naïve PD subjects and controls. Afterwards, PD subjects were included in a 2-year longitudinal study to evaluate disease progression in relation to baseline bilirubin levels. RESULTS: Seventy-five de novo PD subjects were selected and matched with 75 controls by propensity score. Analysis of variance showed higher bilirubin levels in PD patients compared with controls (P < 0.001). Linear regression analysis failed to show a relationship between bilirubin and Unified Parkinson's Disease Rating Scale (UPDRS) part III (P = 0.283) at baseline evaluation. At 2-year follow-up, indirect relationships between bilirubin levels and UPDRS part III (P = 0.028) and between bilirubin levels and levodopa-equivalent daily dosage (P = 0.012) were found. CONCLUSIONS: Parkinson's disease subjects showed higher levels of bilirubin compared with controls. Bilirubin increase might be due to HO overexpression as a compensatory response to oxidative stress occurring from early stages of PD.

Cognitive performances and DAT imaging in early Parkinson's disease with mild cognitive impairment: a preliminary study.

OBJECTIVES: Mild cognitive impairment (MCI) is a common feature in Parkinson's disease (PD). We performed an exploratory study to investigate dopaminergic nigrostriatal innervation and its cognitive correlates in early untreated PD patients with MCI as compared to cognitively intact patients. PATIENTS AND METHODS: A consecutive series of 34-de-novo, drug-naïve patients with PD were enrolled. They underwent [123-I] FP-CIT SPECT and comprehensive neuropsychological battery. MCI was identified in 15 of 34 patients with PD. RESULTS: The two groups did not show any statistically significant difference in age, sex, disease duration, education, lateralization, and H&Y and Hospital Anxiety and Depression Scale scores. Logistic regression analysis showed that UPDRS-III was weakly associated with MCI (P = 0.034). Partial correlation analysis controlling for UPDRS-III and age suggested that in PD patients with MCI reduced V3″ values in the more affected caudate were correlated with reduced performances in frontal assessment battery, Trail Making Test: part B minus Part A and copy task of the Rey-Osterrieth complex figure test. Reduced V3″ values in the more and less affected putamen were significantly related with reduced performance in frontal assessment battery and in copy task of Rey-Osterrieth complex figure test, respectively. No correlation was found between neuropsychological scores and DAT availability in PD patients without MCI. CONCLUSIONS: Although preliminary, our results suggest that striatal dopamine depletion may contribute to some cognitive deficit in early never treated PD patients with MCI.

Presence and progression of non-motor symptoms in relation to uric acid in de novo Parkinson's disease.

BACKGROUND AND PURPOSE: Uric acid (UA) has been studied extensively as a valuable biomarker of Parkinson's disease (PD), but its relationship with non-motor symptoms (NMS) in de novo PD has been poorly investigated. Our aim was to evaluate the usefulness of baseline serum UA as a marker of NMS progression in newly diagnosed PD. METHODS: Sixty-nine newly diagnosed PD patients were enrolled. At baseline, all patients completed the NMS questionnaire (NMSQuest), and serum UA levels were measured. After 2 years, the NMSQuest was completed again and patients were categorized into four groups: NMS improvement (domain involvement at baseline but not at 2-year follow-up visit), NMS absence (domain not involved at baseline or 2-year follow-up visits), NMS presence (domain involvement both at baseline and 2-year follow-up visits) and NMS worsening (domain not involved at baseline but involved at 2-year follow-up). RESULTS: ANOVA with post hoc Bonferroni correction showed that patients with NMS absence presented significantly higher UA values than patients with NMS presence with regard to the attention/memory (P = 0.023), depression/anxiety (P = 0.028) and cardiovascular domains (P = 0.002), whilst no differences were found with regard to both the NMS improvement and worsening groups. In addition, multinomial regression analysis showed that the lowest tertile of NMS progression presented higher UA levels (P = 0.023; odds ratio 0.488) compared with patients with greater NMS progression. CONCLUSIONS: This is the first report of a relationship between serum UA and presence/progression of multiple NMS in de novo PD, providing additional evidence of the reliability of UA as a biomarker of PD and opening new insights on PD neuroprotection.

Uric acid relates to dopamine transporter availability in Parkinson's disease.

BACKGROUND: Diagnosing Parkinson's disease (PD) and tracking its progression may require the combination of reliable biomarkers. Among them, both serum uric acid (UA) and dopamine transporter (DaT) binding deserve more investigations. AIMS OF THE STUDY: We aimed to investigate the relationship between serum UA levels and DaT availability in newly diagnosed, drug-naïve PD patients, by means of semiquantitative [(123) I]FP-CIT-SPECT. METHODS: We recruited 52 newly diagnosed, drug-naïve PD patients, and performed serum UA dosage and [(123) I]FP-CIT-SPECT. RESULTS: Pearson's correlation analysis showed that UA levels were significantly higher in patients with higher averaged, ipsilateral and contralateral DaT binding in caudate, putamen, and striatum. CONCLUSIONS: We showed, for the first time, by regional semiquantitative analysis of DaT binding in PD patients that UA levels significantly correlates with the severity of dopaminergic impairment in caudate, putamen, and striatum. This study broadens our knowledge on the importance of UA as a biomarker of PD.

Relationship between apathy and cognitive dysfunctions in de novo untreated Parkinson's disease: a prospective longitudinal study.

BACKGROUND AND PURPOSE: Apathy may be either a symptom of major depression or a behavioral disturbance occurring in concomitance with depression or alone in Parkinson's disease (PD). The aim of the present study was to determine the progression of cognitive impairment in drug-naïve untreated PD patients with or without clinically significant apathy. METHODS: Sixty-two PD patients with a disease duration <2 years and without history of present or past therapy with pro-dopaminergic agents were included and underwent the Apathy Evaluation Scale (S-AES), a clinical interview based on diagnostic criteria for apathy and a comprehensive neuropsychological battery to assess memory, frontal functions and visuospatial functions. Two years after the first assessment, all patients were re-evaluated on the S-AES, a clinical interview and neuropsychological tests. RESULTS: According to the cut-off value of the S-AES and diagnostic criteria for apathy, eight patients experienced apathy at both baseline and follow-up (A+A+), nine patients had apathy only at follow-up (A-A+), 37 patients never experienced apathy (A-A-) and eight patients showed apathy at the baseline only (A+A-). Cognitive performance significantly declined in all four groups. At both baseline and follow-up A+A+ performed worse than A-A- on visuospatial and frontal tests; A-A+ had lower scores than A-A- on the interference task of the Stroop test (IT-ST). Regression analysis showed that poor performance on the IT-ST at baseline was the only independent predictor of onset of apathy at follow-up. CONCLUSIONS: The results indicated a relationship between apathy and dysexecutive syndrome in early PD. Reduced scores on the IT-ST may predict development of apathy in PD patients.

Insulin-like growth factor-1 predicts cognitive functions at 2-year follow-up in early, drug-naïve Parkinson's disease.

BACKGROUND AND PURPOSE: Cognitive impairment is common in Parkinson's disease (PD), even in the early stages. We aimed to assess the relationship between insulin-like growth factor-1 (IGF-1) and cognitive functions in early, drug-naïve patients with PD. METHODS: Serum IGF-1 was measured in 65 early, drug-naïve patients with PD that underwent a complete neuropsychological battery at baseline and after 2 years. Linear regression analysis was used to evaluate the relationships between neuropsychological scores and IGF-1. Repeated-measures anova was applied to assess changes in neuropsychological variables over time. RESULTS: At baseline, IGF-1 levels were related to phonological fluency. At follow-up, IGF-1 levels were associated with the Rey auditory verbal learning test (RAVLT) - immediate and delayed recall, Frontal Assessment Battery, verbal span and Benton judgement of the line orientation test. Patients with low IGF-1 levels at baseline showed a significantly faster decline of performances than patients with high IGF-1 levels on immediate and delayed recall of the RAVLT and interference task of the Stroop test. CONCLUSIONS: Low serum IGF-1 levels are related to poor performance on executive tasks in early, drug-naïve patients with PD, and may predict poor performance on attention/executive and verbal memory tasks after a 2-year follow-up.

Mild cognitive impairment in drug-naive patients with PD is associated with cerebral hypometabolism.

OBJECTIVE: To characterize brain metabolic changes associated with mild cognitive impairment (MCI) in drug-naive patients with Parkinson disease (PD) using (18)F-fluorodeoxyglucose (FDG) and PET (FDG-PET). METHODS: This cross-sectional study included newly diagnosed patients with PD with MCI in single or multiple domain (PD-MCI; n =12) and without MCI (PD-nMCI; n =12), and healthy controls (n =12). The groups were matched for age. Moreover, the patient groups were matched for motor disability. All subjects underwent a FDG-PET study. Cerebral regional relative metabolic maps were compared in PD-MCI, PD-nMCI, and controls using regions of interest analysis (ROIs) and voxel-based analysis with statistical parametric mapping. RESULTS: ROIs and voxel-based analyses revealed significant relative hypometabolism in the prefrontal, superior/inferior parietal, and associative occipital cortices as well as in the striatum in patients with PD-MCI relative to controls (p < 0.05) and to a lesser extent in patients with PD-nMCI. In contrast, patients with PD-nMCI did not show significant metabolic changes as compared to controls. CONCLUSION: MCI in patients with PD is associated with cortical hypometabolism since the earliest stage, independent of therapy or motor disability. The early involvement of posterior cortical region, a pattern shared by advanced stages of PD-MCI and PD with dementia, could represent an early marker of dementia. The relevance of this pattern in predicting prodromal dementia has to be evaluated in longitudinal studies.

The GH-IGF system in amyotrophic lateral sclerosis: correlations between pituitary GH secretion capacity, insulin-like growth factors and clinical features.

BACKGROUND AND PURPOSE: The growth hormone (GH) and insulin-like growth factor (IGF) system may be involved in neurodegenerative processes, and some abnormalities have been reported in amyotrophic lateral sclerosis (ALS). Our aim was to investigate the GH-IGF axis in patients with ALS and evaluate correlations between this endocrine system and clinical features. METHODS: Serum levels of GH, IGF-I, IGF-II, insulin, IGF-binding protein 1 (IGF-BP1), and IGF-binding protein 3 (IGF-BP3) were measured in 25 patients with ALS and 25 age-, gender-, and BMI-matched healthy controls. A GHRH plus arginine test was performed in patients and controls. Clinical status of patients was evaluated with the ALS Functional Rating Scale - Revised (ALSFRS-R) and upper motor neuron (UMN) score. RESULTS: GHRH plus arginine test showed GH deficiency (GHD) in 13 (52%) patients with ALS; severe GHD was found in 6 (24%) and partial GHD in 7 (28%) patients. IGF-I levels were significantly higher in patients with ALS than in healthy controls (182.9 +/- 90.8 vs. 139.4 +/- 58.1 ng/ml; P = 0.015). IGF-I levels were higher in patients with ALS with UMN score >10 than those with UMN score <10 (217.8 +/- 100.8 vs. 155.5 +/- 74.6 ng/ml, P = 0.05). IGF-II levels were significantly lower in patients with ALS than in healthy controls (720.9 +/- 215 vs. 1001.9 +/- 475.4 ng/ml; P = 0.03). CONCLUSIONS: The results demonstrate an impairment of the GH-IGFs system in ALS. The degenerative process in ALS might lead to a compensatory increase in IGF-I in an attempt to provide additional support to motor neurons or degenerating muscle fibers. The decrease in IGF-II levels may also be of pathological significance.

Comportamento da reticulometria antes e após a suplementação dietética ferrosa em crianças com anemia ferropriva em Erechim - RS / Reticulometry behavior before and after the dietetic ironing supplementation in iron deficiency anemic in Erechim - RS

Na evolução eritropoética, os reticulócitos representam a hemácia mais imatura do sangue circulante. A diminuição de hemoglobina, contida nas hemácias, chama-se anemia e é causada principalmente pelo déficit de ferro. Objetivou-se fazer uma análise do comportamento dos valores de hemoglobina e da contagem de reticulócitos, antes e após a suplementação dietética. Trabalhouse com crianças anêmicas, com idade entre 1 e 13 anos, num grupo inicial de 125 crianças, pertencentes às creches Mãezinha do Céu, Obra Santa Marta e do Centro de Atendimento à Família Erechinense (CAFE). O aporte férrico fornecido contém leite enriquecido com ferro aminoácido quelato, na quantidade 15mg/dia, adicionados a 500ml de leite, com duração de 2 meses, sem interrupções O presente trabalho indicou, através do hemograma, um total de 53 crianças anêmicas. Destas, 43 fizeram ambas as coletas, caracterizando,portanto, o grupo de estudo (n). Ao final deste período, procedeu-se a novos hemogramas, com acompanhamento médico.Obteve-se após a intervenção, um incremento nos resultados dos parâmetros analisados. Percebeu-se que o metal utilizado, juntamente com o veículo empregado, foi efetivo para a melhora nos níveis de hemoglobina e hamatócrito. Observou-se, também, uma melhora nos valores reticulocitários analisados, tanto quanto da hemoglobina.

In the eritropoetic evolution the reticulocytes represent the most immature blood circulating red cell. The diminishing of the hemoglobin contained in the red cell is called anemia and is cause by the iron deficit. The experiment aimed to analyse the hemoglobin values and reticulocytes number before the dietetic supplementation. The subjects were 125 anemic children from 1 to 13 years old of the Mãezinha do Céu and Obra Santa Marta nurseries belonged to the Centro de Atendimento à Familia Erechinense (CAFE). The iron quantity supplied containes enriched milk with quelato mino cid iron in an amount of mg a day added to ml of milk during two months with no interruption. The experiment results indicated, based on the hemograma, a total of 53 anemic children.43 out of them, the study group, did the two blood harvesting. Later on this new hemograms were made supported by medical aid. Results showed that the iron used together with the enriched milk were effective in the anemia improvement levels. Improvement related to the analysed reticulocitary values as the hemoglobin, was notice.

Smoking rain clouds over the Amazon.

Heavy smoke from forest fires in the Amazon was observed to reduce cloud droplet size and so delay the onset of precipitation from 1.5 kilometers above cloud base in pristine clouds to more than 5 kilometers in polluted clouds and more than 7 kilometers in pyro-clouds. Suppression of low-level rainout and aerosol washout allows transport of water and smoke to upper levels, where the clouds appear "smoking" as they detrain much of the pollution. Elevating the onset of precipitation allows invigoration of the updrafts, causing intense thunderstorms, large hail, and greater likelihood for overshooting cloud tops into the stratosphere. There, detrained pollutants and water vapor would have profound radiative impacts on the climate system. The invigorated storms release the latent heat higher in the atmosphere. This should substantially affect the regional and global circulation systems. Together, these processes affect the water cycle, the pollution burden of the atmosphere, and the dynamics of atmospheric circulation.

Clinical presentation and treatment of Wilson's disease: a single-centre experience.

Thirty patients with Wilson's disease (WD) were observed at a movement disorder clinic between 1970 and 2000. Disease onset was at the mean age (SD) of 14.5 (+/-5.9) years. Presentation with hepatic disease occurred in 12 of 30 patients and with neurologic disease in 15. Three patients were asymptomatic at the time of diagnosis. The mean (SD) delay to diagnosis was 5.9 (+/-5.7) years. Five patients diagnosed in an advanced stage of disease died before initiating treatment. Eighteen patients were followed and treated with D-penicillamine alone or in combination with zinc sulphate. Treatment improved most of neurological symptoms. Dystonic postures, behavioural disturbances and dysarthria were the most resistant neurological signs. 'Pseudo-sclerotic' neurologic involvement predicted a good outcome, whereas hepatic onset and 'classic' neurologic involvement were associated with a poorer prognosis. Two of the 18 treated patients died of hepatic failure due to voluntary discontinuation of therapy. Both D-penicillamine and zinc sulphate were well tolerated. No teratogenic effect of D-penicillamine was observed throughout 5 pregnancies. Our results suggest that D-penicillamine or a combination of D-penicillamine and zinc sulphate is a safe and effective long-term treatment in patients with WD.

Inhibition of adipogenesis by Wnt signaling.

Wnts are secreted signaling proteins that regulate developmental processes. Here we show that Wnt signaling, likely mediated by Wnt-10b, is a molecular switch that governs adipogenesis. Wnt signaling maintains preadipocytes in an undifferentiated state through inhibition of the adipogenic transcription factors CCAAT/enhancer binding protein alpha (C/EBPalpha) and peroxisome proliferator- activated receptor gamma (PPARgamma). When Wnt signaling in preadipocytes is prevented by overexpression of Axin or dominant-negative TCF4, these cells differentiate into adipocytes. Disruption of Wnt signaling also causes transdifferentiation of myoblasts into adipocytes in vitro, highlighting the importance of this pathway not only in adipocyte differentiation but also in mesodermal cell fate determination.

Oxytocin does not induce a rise in intracellular free calcium in human breast cancer cells.

Research suggests that oxytocin acts as a growth modulating agent for breast cancer cells. However, the signaling mechanisms responsible for these modulatory effects have not been fully elucidated. In the physiological setting oxytocin is known to stimulate contraction of myometrial cells in the uterus and myoepithelial cells in the breast by increasing intracellular free calcium ([Ca2+]i). The expression of oxytocin receptor mRNA in T-47D breast cancer cells, and four additional breast cancer cell lines (BT-549, MCF-7, MDA-MB- 231, ZR-75-1), was confirmed by RT-PCR analysis. Oxytocin-induced changes in [Ca2+]i in indo-1 AM loaded T-47D breast cancer cells were monitored using flow cytometric analysis. In this cell line, oxytocin (0, 1, 10, 100, and 1,000 nM) did not induce a dose-dependent increase in the mean 405 nm/485 nm emission ratio. These results indicate that oxytocin signaling in T-47D breast cancer cells does not appear to involve an increase in [Ca2+]i.

Preoperative predictors of cost in Medicare-age patients undergoing coronary artery bypass grafting.

BACKGROUND: Identification of preoperative factors that contribute to the cost of coronary artery bypass grafting could aid in predicting the procedure's expense. In this study, 30 sociodemographic and clinical preoperative factors were examined with "survival analysis" techniques to determine characteristics related to total hospital cost. METHODS: Characteristics of all patients age 65 or older undergoing isolated coronary artery bypass grafting from July 1993 to April 1995 (n = 757) were recorded. Software was developed within the hospital's Transitions Systems, Inc, database to calculate the outcome variable of total cost. Nonparametric methods were used for the univariate analysis of the data, and the Cox proportional hazards model was used for the multivariable analysis, censoring 25 patients who died in the hospital. RESULTS: Median hospital cost from the day of the operation until discharge was $15,198. Median length of stay after the operation was 6 days. Multivariable analysis revealed that age, preoperative renal failure, history of cerebrovascular accident, low ejection fraction, and surgical urgency were independent predictors of total cost. CONCLUSIONS: This study, using an accurate representation of true hospital cost and a modeling technique that accounts for the confounding effect of in-hospital death on cost, provides a template for analysis of cost in other patient groups.

Expression of all known vasopressin receptor subtypes by small cell tumors implies a multifaceted role for this neuropeptide.

Vasopressin is one of several small neuropeptides that are reported to be autocrine growth factors for small cell carcinoma of the lung (SCCL). It has been assumed that this peptide exercises its mitogenic influences through the vasopressin V1a receptor, and we have previously demonstrated that this receptor is expressed by classical and variant SCCL. Activation of the vasopressin V1a receptor produces changes in phospholipases C, D, and A2, in protein kinase C, and in Ca2+ mobilization. This study demonstrates that SCCL cells express not only vasopressin V1a receptors but also mRNAs and proteins representing normal V1b receptors and V2 receptors. They were also shown to express mRNA for a human form of the putative receptor rabbit vasopressin-activated calcium-mobilizing receptor (VACM-1). Additionally, SCCL tumor cells were found to express mRNA and protein representing a possible nonfunctional, shortened, "diabetic" form of the vasopressin V2 receptor that is the product of incomplete posttranscriptional splicing. At least four of these five vasopressin receptors were produced by cell lines exemplifying classical and variant forms of SCCL. No differences in the sequences for the V1 receptors between classical and variant SCCL were found. However, although the nature and expression of both vasopressin V1 receptors and human VACM are apparently unaffected by dedifferentiation in SCCL, only the abnormal (and probably nonfunctional) form of the V2 receptor could be demonstrated in variant cell line NCI H82. Functional engagement of vasopressin V2 receptors is reported to produce rises in cAMP and activation of protein kinase A, whereas stimulation of V1b receptors is believed to produce similar changes to those produced by V1a receptors, i.e., activation of phospholipases and of protein kinase C. Stimulation of VACM receptors raises intracellular free Ca2+ through currently unknown but phosphoinositide-independent mechanisms. The presence of all known vasopressin receptors that are, together, potentially capable of inducing several different transduction cascades in small cell tumor cells suggests that this peptide serves a multifaceted role in tumor physiology.

Insulin-like growth factor-I effects on gonadotropin-releasing hormone biosynthesis in GT1-7 cells.

The immortalized GT1-7 cell line synthesizes and secretes GnRH, the key hormone of reproduction. However, GT1-7 cells lack the normal inputs from neurotransmitters, growth factors, and steroids, which are involved in the maturation and maintenance of GnRH neurons in the brain. We examined the effects of the neurotrophic factor insulin-like growth factor-I (IGF-I) on GnRH gene expression and the mechanism for these changes. Initially, effects of IGF-I on GnRH gene expression were determined by ribonuclease protection assay. In time-course experiments, IGF-I treatment caused significant increases in nuclear GnRH primary transcript levels, an index of GnRH gene transcription, 4 and 8 h after initiation of IGF-I treatment. GnRH messenger RNA (mRNA) levels in the cytoplasm were stimulated by IGF-I at 24 h of treatment. IGF-I also affected GT1-7 cell morphology, with an increase in process extension and cell-cell contacts. In contrast, GnRH peptide levels in the medium were initially stimulated and then suppressed by IGF-I, indicating an uncoupling of biosynthesis and secretion. The increase in GnRH mRNA levels induced by IGF-I is probably caused by a transcriptional mechanism, as evidenced by the increase in GnRH primary transcript levels before a change in GnRH mRNA levels, as well as our finding of a similar GnRH mRNA half-life for both control and IGF-I-treated cells. Interestingly, GT1-7 cells themselves were observed to express IGF-I immunoreactivity, suggesting the possibility of autoregulation by this neurotrophic factor. It is concluded that IGF-I is an important modulator of GnRH gene expression and release in the GT1-7 cell line. The reported stimulatory effects of IGF-I in vivo, and its hypothesized role in the development of GnRH neurons in the brain, suggest that IGF-I may make the GT1-7 cells line more like a mature GnRH neuron, as a model for future studies.

Functional vasopressin V1 type receptors are present in variant as well as classical forms of small-cell carcinoma.

Vasopressin and other neuropeptides are believed to serve as autocrine growth factors for small-cell carcinoma of the lung (SCCL), and these mitogenic influences are reported to involve increases in intracellular Ca2+. Of the classical and variant forms of SCCL, the latter is not only more drug-resistant but also refractory to vasopressin, and other peptides, with respect to changes in intracellular Ca2+. It is currently unclear if this refractiveness of variant SCCL is due to the absence of involved peptide receptors, to the production of abnormal receptors, or to abnormalities in components of induced transduction cascades. In this study, the presence of structurally-normal and functional vasopressin V1a receptors, was examined in a classical SCCL cell line (NCI H345) that is Ca(2+)-responsive to vasopressin, and a variant SCCL cell line (NCI H82) that is unresponsive in this regard to the peptide. Both cell lines were shown to express an mRNA of 1.9 Kb for the vasopressin V1a receptor. RT-PCR, cloning, and DNA sequencing revealed the structure of the mRNA was identical for both cell lines, and, in turn, identical to the mRNA expressed for this receptor by human liver cells. In both cell lines and liver, this mRNA was shown by Western analysis and RIA to generate major protein products of approximately 70,000 and 43,000 daltons. Vasopressin action on NCI H82 cells resulted in a substantial rise in the levels of total inositol phosphates. However, it was reaffirmed that these changes in inositol phosphates were not accompanied by a rise in Ca2+ levels. All of these data indicate that variant SCCL, as well as classical SCCL, expresses structurally-normal and functional vasopressin V1a receptors, but their activation in variant SCCL raises IP3 levels without a corresponding rise in intracellular Ca2+. This difference between the two SCCL sub-types therefore involves either steps in the inositol triphosphate cascade beyond the activation of phospholipase C, or alternatively, components of other transduction events that might be involved with changes in intracellular Ca2+.

Expression of colonic H-K-ATPase mRNA in cortical collecting duct: regulation by acid/base balance.

In addition to the gastric isoform of H-K-ATPase, the colonic isoform is also expressed in the kidney, but its intrarenal localization and exact function are not known. The goal of this study was to determine whether the colonic H-K-ATPase is expressed in the rabbit cortical collecting duct (CCD) and whether it is regulated by changes in acid/base balance. With quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) with RNA isolated from immunodissected rabbit CCD cells and degenerate oligonucleotide primers, a PCR product of the predicted size (approximately 430 bp) was amplified. The amplified DNA was further characterized by nested PCR and sequencing. Direct sequencing of the 434-bp PCR product revealed 83% identity at the nucleotide level and an 80.4% identity at the deduced amino acid level to the rat colonic H-K-ATPase. With the same primers and cDNA originating from rabbit distal colon, a DNA fragment with a size and nucleotide sequence identical to that originating from CCD cells was amplified. Furthermore, using PCR screening, we isolated and sequenced a 1.5-kb cDNA clone from a rabbit CCD library. The predicted amino acid sequence of the protein encoded by this cDNA is 85 and 82% identical to the corresponding regions of the guinea pig and rat colonic H-K-ATPase, respectively, and 70% identical to the H-K-ATPase recently cloned from Bufo marinus, whereas it shows only 45 and 42% homology to the rat Na-K-ATPase alpha 1-subunit and the rat gastric H-K-ATPase, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)