Calcineurin inhibitor cyclosporine A activates renal Na-K-Cl cotransporters via local and systemic mechanisms.

Calcineurin dephosphorylates nuclear factor of activated T cells transcription factors, thereby facilitating T cell-mediated immune responses. Calcineurin inhibitors are instrumental for immunosuppression after organ transplantation but may cause side effects, including hypertension and electrolyte disorders. Kidneys were recently shown to display activation of the furosemide-sensitive Na-K-2Cl cotransporter (NKCC2) of the thick ascending limb and the thiazide-sensitive Na-Cl cotransporter (NCC) of the distal convoluted tubule upon calcineurin inhibition using cyclosporin A (CsA). An involvement of major hormones like angiotensin II or arginine vasopressin (AVP) has been proposed. To resolve this issue, the effects of CsA treatment in normal Wistar rats, AVP-deficient Brattleboro rats, and cultured renal epithelial cells endogenously expressing either NKCC2 or NCC were studied. Acute administration of CsA to Wistar rats rapidly augmented phosphorylation levels of NKCC2, NCC, and their activating kinases suggesting intraepithelial activating effects. Chronic CsA administration caused salt retention and hypertension, along with stimulation of renin and suppression of renal cyclooxygenase 2, pointing to a contribution of endocrine and paracrine mechanisms at long term. In Brattleboro rats, CsA induced activation of NCC, but not NKCC2, and parallel effects were obtained in cultured cells in the absence of AVP. Stimulation of cultured thick ascending limb cells with AVP agonist restored their responsiveness to CsA. Our results suggest that the direct epithelial action of calcineurin inhibition is sufficient for the activation of NCC, whereas its effect on NKCC2 is more complex and requires concomitant stimulation by AVP.

5'-heterogeneity of glucocorticoid receptor messenger RNA is tissue specific: differential regulation of variant transcripts by early-life events.

Glucocorticoid receptor (GR) gene expression is regulated in a complex tissue-specific manner, notably by early-life environmental events that program tissue GR levels. We have identified and characterized several new rat GR mRNAs. All encode a common protein, but differ in their 5'-leader sequences as a consequence of alternate splicing of, potentially, 11 different exon 1 sequences. Most are located in a 3-kb CpG island, upstream of exon 2, that exhibits substantial promoter activity in transfected cells. Ribonuclease (RNase) protection analysis demonstrated significant levels of six alternate exons 1 in vivo in rat, with differences between liver, hippocampus, and thymus reflecting tissue-specific differences in promoter activity. Two of the alternate exons 1 (exons 1(6) and 1(10)) were expressed in all tissues examined, together present in 77-87% of total GR mRNA. The remaining GR transcripts contained tissue-specific alternate first exons. Importantly, tissue-specific first exon usage was altered by perinatal environmental manipulations. Postnatal handling, which permanently increases GR in the hippocampus, causing attenuation of stress responses, selectively elevated GR mRNA containing the hippocampus-specific exon 1(7). Prenatal glucocorticoid exposure, which increases hepatic GR expression and produces adult hyperglycemia, decreased the proportion of hepatic GR mRNA containing the predominant exon 1(10), suggesting an increase in a minor exon 1 variant. Such tissue specificity of promoter usage allows differential GR regulation and programming.

Differential regulation of corticosteroid receptors by monoamine neurotransmitters and antidepressant drugs in primary hippocampal culture.

Hyperactivity of the hypothalamic-pituitary-adrenal axis is a characteristic feature of depressive illness. The centrally located corticosteroid receptors, the glucocorticoid and mineralocorticoid receptors, are thought to be important modulators of this axis and changes in the levels of these receptors, particularly in the hippocampus, may underlie the hyperactivity observed. Various antidepressant drugs increase hippocampal mineralocorticoid and glucocorticoid receptor levels in vivo. These effects are thought to be mediated via alterations in monoaminergic neurotransmission. We examined whether serotonin (5HT) and noradrenaline (NA) have direct effects on glucocorticoid receptor and mineralocorticoid receptor expression in primary hippocampal neurones, and whether antidepressants also exert direct effects on target neurones. Exposure of hippocampal cells to 5HT for 4 days increased both glucocorticoid and mineralocorticoid receptor mRNA and protein expression. The induction of mineralocorticoid receptor mRNA was completely blocked by the 5HT(7) receptor antagonist SB 269970. In contrast glucocorticoid receptor induction was insensitive to the 5HT(7) receptor, whilst studies with the 5HT(1A) receptor agonist 8-hydroxy-2-(di-n-proplamino) tetralin hydrochloride and the 5HT(1A) receptor antagonist N-[2-[4-2-[O-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohexane carboxamide trihydrochloride (WAY 100635) suggest a partial role for 5HT(1A) receptors in hippocampal glucocorticoid receptor regulation. Treatment with NA for 4 days also increased glucocorticoid receptor expression but had no effect on mineralocorticoid receptor expression. This was blocked by propanolol suggesting action via beta-adrenergic receptors. Similarly to NA, fluoxetine and amitriptyline also selectively increased glucocorticoid receptor mRNA and protein levels over this time course. However, glucocorticoid receptor induction by fluoxetine or amitriptyline was not blocked by WAY 100635 or propanolol. These results show that 5HT, NA and antidepressants act directly but via distinct mechanisms on hippocampal neurones to regulate mineralocorticoid and glucocorticoid receptor expression. Thusly, manipulation of neurotransmitter or antidepressant levels in the brain may aid in reversing hypothalamic-pituitary-adrenal axis hyperactivity by restoring hippocampal corticosteroid receptor balance.

Monocyte esterase deficiency in gastrointestinal cancer.

AIM: To substantiate the high incidence of monocyte esterase deficiency (MED) in gastrointestinal carcinoma already reported in a small group of patients; to compare the clinical findings in esterase deficient and esterase positive patients. METHODS: Peripheral blood smears (n = 22) or cytocentrifuge preparations (n = 52) of mononuclear cells from the peripheral blood of patients with gastrointestinal carcinoma were stained by the non-specific esterase stain (pH 5.8) using a batch technique. Samples containing > or = 85% esterase negative monocytes were identified at light microscopic examination. RESULTS: Seven of 74 patients were identified as having MED. This correlated exactly with the proportion (five of 46) found before, using an automated method, and was significantly higher than the 0.8% incidence in normal blood donors shown in that study. Comparison of the clinical details of the 12 MED patients with those of 105 esterase positive patients showed a significantly longer disease free survival in the MED cohort and increased occurrence of benign neoplasms--largely colorectal polyps--in this group also. Three patients had a borderline degree of deficiency and were excluded from comparisons, although they showed the same clinical tendencies as the MED group. CONCLUSIONS: There is a strong degree of association between monocyte esterase deficiency and gastrointestinal carcinoma. Further evidence must be sought to prove that the deficiency precedes the disease and therefore may predispose to it, or at least may identify subjects with such a predisposition. This could lead to early diagnosis and effective treatment of gastrointestinal carcinoma in a sizeable proportion of patients.

Monocyte esterase deficiency in malignant neoplasia.

A survey of the incidence of monocyte esterase deficiency in 4000 inpatients (including 808 with malignant neoplastic disease) and 474 normal controls was performed using an automated esterase method. A highly significant excess of patients with malignant disease and the deficiency was evident when compared with normal controls or all other patients. Within the group of patients with malignant disease the demonstrable excess occurred in B chronic lymphocytic leukaemia, non-Hodgkin's and Hodgkin's lymphoma, and carcinoma of the gastrointestinal tract. There was also a significant excess of patients with the deficiency attending the renal unit, both among patients who had had renal transplants and those who had not. A familial incidence of monocyte esterase deficiency was found in 19 (35%) of first degree relatives of those patients in whom family studies were done. It is suggested that the reason for the increased prevalence of the anomaly in these disorders might be that the diminution of esterase activity has a role in their development.

Effects of attention training on information processing in schizophrenia.

This study evaluated the impact of a cognitive retraining intervention designed to enhance the attention skills of schizophrenia patients. The dependent variables included measures of perceptual sensitivity and sustained vigilance derived from a visual continuous performance test, as well as visual span of apprehension and world-list recall. Sixteen subjects received approximately 15 hours of repeated practice with computer-mediated vigilance tasks. Seventeen subjects were assigned to a no-treatment control group. All subjects were rated on measures of negative and positive symptoms before treatment. Despite improved performance on the training tasks, no significant changes on the outcome measures were observed following treatment. Thus, it is suggested that cognitive rehabilitation interventions with schizophrenia patients stress the teaching of behavioral strategies that bypass deficits, rather than remediating deficiencies in basic abilities, such as attention.

WNK kinases regulate sodium chloride and potassium transport by the aldosterone-sensitive distal nephron.

With-No-Lysine [K] (WNKs) are a recently discovered family of serine/threonine protein kinases that contain a uniquely structured catalytic domain. Mutations in the genes encoding two family members, WNK1 and WNK4, cause a chloride-dependent, thiazide-sensitive inherited syndrome of hypertension and hyperkalemia. Over the past 5 years, physiologic studies have demonstrated that these proteins regulate transcellular and paracellular epithelial ion flux. In this mini review, we discuss WNK1 and WNK4 gene products and their regulatory effects on sodium chloride and potassium handling in the aldosterone-sensitive distal nephron. Experimental observations regarding the effects of these proteins on transport processes mediated by the thiazide-sensitive Na-Cl co-transporter, the epithelial sodium channel, the renal outer medullary potassium channel, and the paracellular pathway integrate into a model that suggests an essential role for WNKs in coordinating renal Na-Cl reabsorption and K(+) secretion.

Lactoferrin-inducible monocyte cytotoxicity for K562 cells and decay of natural killer lymphocyte cytotoxicity.

Monocyte-enriched and lymphocyte-enriched fractions of peripheral blood from three healthy volunteers were obtained by percoll density gradient centrifugation. The cytotoxic activity of each fraction against 51Cr-labelled K562 cells was quantified in a 2-h assay using freshly isolated cells of each fraction and cells of each fraction which had been incubated with and without lactoferrin in complete medium for 18 h before performing the assay. We have thereby shown that cytotoxicity was not demonstrable in the lymphocyte fraction (containing 7.3 +/- 2% large granular lymphocytes) after 18 h in medium, whereas the cytotoxicity of the monocyte fraction (containing 3 +/- 0.4% large granular lymphocytes) was still significantly increased (P less than or equal to 0.01) and that lactoferrin had no effect on lymphocyte fraction cytotoxicity while producing an 11-fold increase in the cytotoxicity of the monocyte fraction. It is therefore possible to perform a relatively simple test of monocyte cytotoxicity using lactoferrin as a stimulant in a 2-h 51Cr-labelled K562 assay system by allowing 18 h to elapse for lymphocyte natural killer cytotoxicity to decay.

Lactoferrin inducible monocyte cytotoxicity defective in esterase deficient monocytes.

We recently demonstrated a higher incidence of monocyte esterase deficiency in patients with lymphoproliferative neoplasia and gastrointestinal carcinoma than in the normal population. Using lactoferrin to stimulate monocyte cytotoxicity we have now compared the abilities of esterase positive and esterase deficient monocytes to lyse K562 cells. The esterase deficient monocytes were from normal subjects whose monocytes have consistently failed to show cytochemical esterase staining over 30-72 months and which lack specific monocyte isoenzymes. The esterase positive monocytes were from age and sex matched control subjects. Esterase positive monocytes responded to lactoferrin stimulation by a five-fold increase in cytotoxicity whereas deficient monocytes failed to produce any response. These results indicate a possible defect in cytotoxicity of esterase deficient monocytes and together with the epidemiological findings suggest a link between monocyte esterase deficiency and neoplasia.

Heredofamilial deficiency of monocyte esterase in patients with rheumatoid arthritis.

Deficiency of the monocyte ectoenzyme non-specific esterase is described in a heredofamilial pattern in four patients with rheumatoid arthritis. No association with HLA status or rheumatoid factor seropositivity was found.