Role of phase angle in the evaluation of effect of an immuno-enhanced formula in post-surgical cancer patients: a randomized clinical trial.

OBJECTIVE: Neoplastic disease is frequently associated with poor nutritional status or severe malnutrition. Diet and nutritional intervention are becoming increasingly important for prognosis and quality of life in cancer patients. Accessible and repeatable tools for assessing nutritional status with body composition techniques seems to be fundamental. The aim of this study was to evaluate the effects of immunonutrition on body composition parameters, inflammatory response and nutritional status in patients at stage III of head and neck squamous carcinoma (HNSCC). PATIENTS AND METHODS: In our work, 50 malnourished subjects with HNSCC staging III were recruited and treated with oral diet (OD) or enteral nutrition (EN). Patient under EN followed, for the first three days, enteral standard nutrition (ESN) and then enteral immunonutrition (EIN). Nutrition state was evaluated on days 0, 3, and 8 through body composition and biochemical analyses. RESULTS: After 8 days, the EIN treatment showed a significant improvement in phase angle, pre-albumin, retinol binding protein and transferrin compared to the OD treatment. CONCLUSIONS: Our results showed that immunonutrition treatment improves the nutritional status of neoplastic patients, supporting chemotherapy. The phase angle is not only a predictor of cancer survival, but has also proved to be useful in the surveillance of nutritional status improvement as well as biochemical indices.

Validation of a short questionnaire to record adherence to the Mediterranean diet: An Italian experience.

BACKGROUND AND AIMS: A greater adherence to the Mediterranean diet has been associated with a reduced risk of major chronic diseases and cancer. The aim of the study was to assess the validity of a new short self-administered 15-item questionnaire (QueMD) to measure adherence to the Mediterranean diet in Italy. METHODS AND RESULTS: Four-hundred and eighty three participants to cancer-screening programmes at the European Institute of Oncology, Milan (Italy) were invited to join this study. Those interested compiled the QueMD and a validated Food Frequency Questionnaire (FFQ) reporting their usual food consumption during the previous six months. We derived the alternate Mediterranean score (aMED) from both questionnaires with values ranging from 0 (minimal adherence) to 9 (maximal adherence). Complete dietary data were available for 343 individuals (participation rates 71.0%). Spearman correlation coefficient between the responses to the 15 questions of the QueMD and corresponding food intake derived from the FFQ ranged from 0.15 to 0.84. A moderate correlation was found between the aMED scores calculated from the QueMD and the FFQ (intraclass correlation coefficient 0.50; 95% CI, 0.42-0.58), while agreement between the two instruments was only poor to fair for 7 of the 9 single items composing the aMED score, with values ranging from 53.0% for wholegrain products to 79.5% for fruits. CONCLUSION: This new self-administered 15-item questionnaire could be a useful tool to assess adherence to the Mediterranean diet in the Italian population.

Quantitative determination of micronization-induced changes in the solid state of lactose.

Lactose, in particular α-lactose monohydrate, is the most used carrier for inhalation. Its surface and solid-state properties play a key role in determining Dry Powder Inhalers (DPIs) performance. Techniques such as X-Ray Powder Diffraction (XRPD) and Differential Scanning Calorimetry (DSC), which are commonly used for the characterization of lactose, are not always capable of explaining the solid-state changes induced by processing, such as micronization. In the present work, the evaluation of the effect of the micronization process on the solid-state properties of lactose was carried out by XRPD and DSC and a satisfactory, although not unequivocal, interpretation of the thermal behaviour of lactose was obtained. Thus, a new gravimetric method correlating in a quantitative manner the weight change in specific sections of the Dynamic Vapour Sorption (DVS) profile and the amount of different forms of α-lactose (hygroscopic anhydrous, stable anhydrous and amorphous) simultaneously present in a given sample was developed and validated. The method is very simple and provides acceptable accuracy in phase quantitation (LOD=1.6, 2.4 and 2.7%, LOQ=5.4, 8.0 and 8.9% for hygroscopic anhydrous, stable anhydrous and amorphous α-lactose, respectively). The application of this method to a sample of micronized lactose led to results in agreement with those obtained by DSC and evidenced that hygroscopic anhydrous α-lactose, rather than amorphous lactose, can be generated in the micronization process. The proposed method may find a more general application for the quantification of polymorphs of compounds different than lactose, provided that the various solid phases afford different weight variations in specific regions of the DVS profile.

Dietary style and acid load in an Italian population of calcium kidney stone formers.

BACKGROUND AND AIMS: Animal protein intake may cause an acid load that predisposes individuals to stones by influencing calcium and citrate excretion. These associations were not confirmed in recent studies. Therefore the present study was aimed to compare acid load of diet in stone formers and controls. METHODS AND RESULTS: Participants to the study were 157 consecutive calcium stone formers and 144 controls. Diet was analyzed in these subjects using a software that evaluated nutrient intake from a three-day food intake diary. This software also estimated the potential renal acid load (PRAL, mEq/day). Twenty-four-hour urine excretion of ions and citrate was measured in stone formers. Stone former diet had lower intake of glucose, fructose, potassium and fiber and higher PRAL in comparison with controls. The multinomial logistic regression analysis showed that stone risk decreased in association with the middle and the highest tertiles of fiber intake and increased in association with the highest tertile of PRAL. The linear multiple regression analysis showed that calcium excretion was associated with the sodium excretion and that citrate excretion was associated with the PRAL and animal protein intake in stone formers. CONCLUSION: Our findings suggest that stone formers may undergo a greater dietary acid load sustained by a low vegetable intake and base provision. Dietary acid load does not appear as the main determinant of calcium excretion, but may promote stone risk by decreasing citrate excretion. Sodium intake may predispose to stones by stimulating calcium excretion.

Blood pressure and sodium intake from snacks in adolescents.

BACKGROUND/OBJECTIVES: The relationship between sodium intake and arterial blood pressure (BP) values in adolescence is still controversial. The intake of high-sodium processed foods as snacks has gone up worldwide. The purpose of the present cross-sectional study was to analyze the association between BP values and sodium intake from snacks. SUBJECTS/METHODS: The mean weekly consumption of snacks was evaluated in 1200 randomly selected adolescents aged 11-13 years by a food-frequency questionnaire; their anthropometric and BP values were measured by trained researchers. A dietary 24-h food-recall questionnaire was randomly given to 400 of the 1200 adolescents. RESULTS: Mean sodium intake from snacks was 1.4 g/day. Systolic and diastolic BP (SBP and DBP, respectively) significantly increased from the lower to the higher tertile of sodium from snacks and with increasing frequency of salty snacks consumption. In a multiple logistic regression model, both being in the highest SBP quartile and in the highest DBP quartile were significantly associated with the intake of sodium from snacks (odds ratio (OR)=1.48; 95% confidence interval (CI) 1.14-1.91 and OR=2.17; 95% CI 1.68-2.79, respectively), the consumption of >2/day salty snacks (OR=1.86; 95% CI 1.32-2.63 and OR=2.38; 95% CI 1.69-3.37, respectively) and body mass index (OR=1.26; 95% CI 1.22-1.31 and OR=1.14; 95% CI 1.10-1.18, respectively) but not with age, sex or exercise levels. In the 400 individuals, the average total sodium intake was 3.1 g/day and was significantly higher in individuals belonging to the highest quartile of SBP and DBP. CONCLUSIONS: Sodium intake from snacks was almost half of the average daily sodium consumption and was significantly associated with BP values in adolescents.

Tumour-associated fibroblasts contribute to neoangiogenesis in human parathyroid neoplasia.

Components of the tumour microenvironment initiate and promote cancer development. In this study, we investigated the stromal component of parathyroid neoplasia. Immunohistochemistry for alpha-smooth muscle actin (α-SMA) showed an abundant periacinar distribution of α-SMA(+) cells in normal parathyroid glands (n=3). This pattern was progressively lost in parathyroid adenomas (PAds; n=6) where α-SMA(+)cells were found to surround new microvessels, as observed in foetal parathyroid glands (n=2). Moreover, in atypical adenomas (n=5) and carcinomas (n=4), α-SMA(+) cells disappeared from the parenchyma and accumulated in the capsula and fibrous bands. At variance with normal glands, parathyroid tumours (n=37) expressed high levels of fibroblast-activation protein (FAP) transcripts, a marker of tumour-associated fibroblasts. We analysed the ability of PAd-derived cells to activate fibroblasts using human bone-marrow mesenchymal stem cells (hBM-MSCs). PAd-derived cells induced a significant increase in FAP and vascular endothelial growth factor A (VEGFA) mRNA levels in co-cultured hBM-MSCs. Furthermore, the role of the calcium-sensing receptor (CASR) and of the CXCL12/CXCR4 pathway in the PAd-induced activation of hBM-MSCs was investigated. Treatment of co-cultures of hBM-MSCs and PAd-derived cells with the CXCR4 inhibitor AMD3100 reduced the stimulated VEGFA levels, while CASR activation by the R568 agonist was ineffective. PAd-derived cells co-expressing parathyroid hormone (PTH)/CXCR4 and PTH/CXCL12 were identified by FACS, suggesting a paracrine/autocrine signalling. Finally, CXCR4 blockade by AMD3100 reduced PTH gene expression levels in PAd-derived cells. In conclusion, i) PAd-derived cells activated cells of mesenchymal origin; ii) PAd-associated fibroblasts were involved in tumuor neoangiogenesis and iii) CXCL12/CXCR4 pathway was expressed and active in PAd cells, likely contributing to parathyroid tumour neoangiogenesis and PTH synthesis modulation.

Psychiatric disorders, suicidality, and personality among young men by sexual orientation.

Personality and its potential role in mediating risk of psychiatric disorders and suicidality are assessed by sexual orientation, using data collected among young Swiss men (n=5875) recruited while presenting for mandatory military conscription. Mental health outcomes were analyzed by sexual attraction using logistic regression, controlling for five-factor model personality traits and socio-demographics. Homo/bisexual men demonstrated the highest scores for neuroticism-anxiety but the lowest for sociability and sensation seeking, with no differences for aggression-hostility. Among homo/bisexual men, 10.2% fulfilled diagnostic criteria for major depression in the past 2weeks, 10.8% for ADHD in the past 12months, 13.8% for lifetime anti-social personality disorder (ASPD), and 6.0% attempted suicide in the past 12months. Upon adjusting (AOR) for personality traits, their odds ratios (OR) for major depression (OR=4.78, 95% CI 2.81-8.14; AOR=1.46, 95% CI 0.80-2.65) and ADHD (OR=2.17, 95% CI=1.31-3.58; AOR=1.00, 95% CI 0.58-1.75) lost statistical significance, and the odds ratio for suicide attempt was halved (OR=5.10, 95% CI 2.57-10.1; AOR=2.42, 95% CI 1.16-5.02). There are noteworthy differences in personality traits by sexual orientation, and much of the increased mental morbidity appears to be accounted for by such underlying differences, with important implications for etiology and treatment.

[Treatement of sex offenders: limits and possibilities]. / Traitement des agresseurs sexuets: possibilités et limites.

Sexual offending is a matter of public concern and of interest to caregivers because of the consequences to the victims. Though there is a high prevalence of paraphilias among sexual aggressors, there is no strict link between aggressive sexual behavior and psychiatric disorders. Several typologies of sex offenders, based on personality and motivation, have been described. According to several studies, recidivism risk, for all known typologies of sex offenders, is estimated to be around 15% at 5 years. The use of standardized scales improves the reliability of the risk assessment. Psychotherapy, with or without a pharmacological treatment, forms the basis of the psychiatric treatment of these patients. Serotoninergic selective reuptake inhibitors, antiandrogens and GnRH analogues are the main drugs that are used.

Reprint of: Vitamin D receptor activation and prevention of arterial ageing.

In chronic kidney disease (CKD) patients, cardiovascular (CV) morbidity and mortality rate is higher than in the general population, because of frequently concomitant hypertension, peripheral vascular disease, heart failure, vascular calcification (VC), diabetes and mineral bone disease. Recently, another important factor associated to CV risk in CKD has been deeply investigated: vitamin D deficiency. Vitamin D Receptors (VDRs) are present in several systems and tissues and VDR activation is associated to positive effects, resulting in better blood pressure control and prevention of diabetic nephropathy. Unfortunately, the natural, non-selective vitamin D receptor activator (VDRA), calcitriol, is associated to higher serum calcium and phosphate levels, thus worsening CV risk in CKD. Recent data showed that the selective VDRA paricalcitol might have ameliorative CV effects. The potential positive impact of the use of paricalcitol on diabetic nephropathy, cardiac disease, hypertension, and VC may open new paths in the fight against CV disease in CKD patients.

Vitamin D receptor activation and prevention of arterial ageing.

In chronic kidney disease (CKD) patients, cardiovascular (CV) morbidity and mortality rate is higher than in the general population, because of frequently concomitant hypertension, peripheral vascular disease, heart failure, vascular calcification (VC), diabetes and mineral bone disease. Recently, another important factor associated to CV risk in CKD has been deeply investigated: vitamin D deficiency. Vitamin D Receptors (VDRs) are present in several systems and tissues and VDR activation is associated to positive effects, resulting in better blood pressure control and prevention of diabetic nephropathy. Unfortunately, the natural, non-selective vitamin D receptor activator (VDRA), calcitriol, is associated to higher serum calcium and phosphate levels, thus worsening CV risk in CKD. Recent data showed that the selective VDRA paricalcitol might have ameliorative CV effects. The potential positive impact of the use of paricalcitol on diabetic nephropathy, cardiac disease, hypertension, and VC may open new paths in the fight against CV disease in CKD patients.

Calcium sensing receptor and renal mineral ion transport.

Calcium sensing receptor (CaSR) is a component of the C family of the G protein-coupled receptors. It is ubiquitously expressed in human and mammal cells but is more expressed in parathyroid glands and kidney cells. It is located on the cell plasma membrane and senses the changes of extracellular calcium concentrations. Thus, it may modify cell functions according to serum calcium levels. CaSR has a key role in calcium homeostasis because it allows parathyroid glands and kidney to regulate PTH secretion and calcium reabsorption in order to keep serum calcium concentration within the normal range. CaSR appears as an important player in the regulation of renal calcium handling and body calcium metabolism. Thus, CaSR may protect human tissues against calcium excess. In kidneys, its protective effect includes the stimulation of diuresis and phosphate retention, along with the potential prevention of calcium precipitation and deposition in kidney tubules and interstitium.

Renal osteodystrophy and vascular calcification.

Chronic kidney disease (CKD) is characterized by phosphate retention and reduced synthesis of 1.25(OH)2-vitamin D stimulating parathyroid hyperplasia. These changes cause a complex osteopathy, defined as renal osteodystrophy, and vascular calcification. Renal osteodystrophy increases the risk of fracture and causes deformities and disability. Vascular calcification occurs in a large proportion of hemodialysis patients and is a marker of arteriopathy. Calcifying arteriopathy induces arterial stiffness and contributes to the high cardiovascular mortality and morbidity among CKD patients. Vascular calcification results from a process of local bone formation induced by osteoblast-like cells developing in the vascular wall from resident cells. Osteoblast differentiation of resident vascular cells may be mediated by metabolic factors and may be induced by high concentrations of phosphate. Therefore, phosphate retention appears as the most detrimental factor affecting arteries in CKD patients. There is no specific therapy to revert soft tissue calcification, but calcification must be prevented in the early stages of CKD.

[What do we know after ten years of genetic research into calcium kidney stones?]. / Quali insegnamenti dopo dieci anni di ricerca genetica sulla calcolosi renale di calcio?

Genetic studies of calcium kidney stones have so far assessed single candidate genes by testing linkage disequilibrium or association between a locus and stone disease. They showed the possible involvement of the calciumsensing receptor gene, vitamin D receptor gene, and bicarbonate-sensitive adenylate cyclase gene. In addition to research in humans, the study of different strains of knock-out mice let us include the gene of phosphate reabsorption carrier NPT2, caveolin-1, protein NHERF-1 modulating calcium and urate reabsorption, osteopontin and Tamm-Horsfall protein among the possible determinants. However, the interactions between genes and also between environmental factors and genes are generally considered fundamental in calcium stone formation. Thus, the genetic studies carried out to date have not led to a significant growth of the knowledge about the causes of calcium kidney stones, even though they have allowed us to assess the size of the problem and define criteria to address it. Further knowledge of the causes of calcium stones may be obtained using the instruments that modern biotechnology and bioinformatics have made available to researchers.

R990G polymorphism of calcium-sensing receptor does produce a gain-of-function and predispose to primary hypercalciuria.

An association between the R990G polymorphism of the CaSR gene, coding for calcium-sensing receptor, and primary hypercalciuria was found in kidney stone formers. To confirm this relationship, we investigated hypercalciuric women without stones and studied the effect of CaSR gene in human embryonic kidney cells (HEK-293). We genotyped for CaSR A986S, R990G, and Q1011E polymorphisms, 119 normocalciuric and 124 hypercalciuric women with negative history of kidney stones. Homozygous (n=2) or heterozygous (n=21) women for the 990G allele considered as one group had an increased risk to be hypercalciuric (odds ratio=5.2; P=0.001) and higher calcium excretion (P=0.005) in comparison with homozygous women for the 990R allele (n=220). HEK-293 cells were transfected with the variant allele at the three CaSR gene polymorphisms and with the most common allele with no variants. The transient increment of intracellular calcium caused by the stepwise increase of extracellular calcium was evaluated in stable transfected cells loaded with fura-2 AM. The extracellular calcium concentration producing the half-maximal intracellular calcium response was lower in HEK-293 cells transfected with the 990G allele than in those transfected with the wild-type allele (P=0.0001). Our findings indicate that R990G polymorphism results in a gain-of-function of the calcium-sensing receptor and increased susceptibility to primary hypercalciuria.

[Calcium kidney stones. Diagnostic and preventive prospects]. / La calcolosi renale di calcio. Prospettive diagnostiche e preventive.

Kidney stone disease is one of the main causes of hospitalization in Italy. Its prevalence increased in the last century and is probably still increasing. The pathogenesis of the disease is not known, although two main theories have been elaborated. The first hypothesizes that hydroxyapatite deposition in the interstitium of the renal papillae (Randall's plaque) precedes urinary calcium oxalate precipitation on the ulcered surface of the papilla to form a stone. The second presumes the tubular lumen of Bellini's duct to be the site where calcium-oxalate salts precipitate to form the nucleus for stone formation within the urinary tract. These pathogenetic processes may be favored by different dietary and genetic factors. The genes involved are not known, although many studies have been performed. Polymorphisms of genes coding for the vitamin D receptor, calcium-sensing receptor, interleukin-1 receptor antagonist, and urokinase were found to be associated with kidney stones, but these results have not been replicated. Different nutrients are suspected to predispose patients to calcium kidney stone disease. A high intake of animal proteins, sodium, vitamin C and oxalate has been implicated in stone formation, whereas calcium, alkalis and phytate may have a protective effect. The prevention of calcium stone formation is based on the recognition of risk factors like those already mentioned here. Furthermore, a family history of kidney stones may be useful in identifying subjects predisposed to become calcium stone formers. However, the expectations of the scientific community are turned to the advances in genetics and to the findings of genetic studies, which may provide diagnostic tools and criteria to define the risk profile of the single individual.

R990G polymorphism of the calcium-sensing receptor and renal calcium excretion in patients with primary hyperparathyroidism.

CONTEXT: Primary hyperparathyroidism (PHPT) shows a great variability in clinical course and severity. Data concerning the association between polymorphic variants of the gene encoding the calcium-sensing receptor (CaSR) and clinical characteristics of PHPT are not conclusive. OBJECTIVE: To evaluate the frequency of three polymorphisms; A986S, R990G, and Q1011E of CaSR in patients with PHPT and to correlate the genotypes with clinical and biochemical parameters. PATIENTS AND METHODS: The study included 94 consecutive unrelated patients referred to our Departments for PHPT diagnosis and management between 2000 and 2005 and 137 age and sex-matched healthy subjects. Patients and controls were genotyped according to standard procedures. Due to the rarity of 990G allele, homozygous and heterozygous subjects were grouped in R/G+G/G set. All PHPT patients were studied for calcium metabolism parameters and renal and bone complications. RESULTS: The proportion of CaSRvariants was similar in PHPT patients and controls. In PHPT patients, only R990G polymorphism was associated with disease parameters; in comparison with R/R, R/G+G/G patients showed lower mean serum parathyroid hormone (PTH) and phosphate levels (139.9 +/- 62.2 vs 199.9 +/- 136.3 pg/ml, P < 0.05 and 0.69 +/- 0.12 vs 0.81 +/- 0.18 mmol/l, P = 0.031 respectively), higher mean 24-h urine calcium concentration and calcium excretion (9.05 +/- 2.05 vs 6.77 +/- 4.31 mmol/24 h, P = 0.012 and 67 +/- 20 vs 51 +/- 26 mumol/l GF, P = 0.039), and increased prevalence of nephrolithiasis (90.0 vs 44.2%, P = 0.007). CONCLUSIONS: The study showed that patients with PHPT, bearing the 990G allele, had lower serum PTH levels and higher urinary calcium excretion in comparison with the other genotype, suggesting an increased sensitivityof the variant receptor to extracellular calcium. Since this variant was associated with increased occurrence of nephrolithiasis, analysis of this polymorphism might help to predict renal complication of the disease.

Erythrocyte calcium influx is related to severity of ventricular arrhythmias in uraemic patients.

BACKGROUND: Myocardial disorders are a remarkable cause of morbidity and mortality in chronic haemodialysed patients (HD). They could be favoured by alteration of cell Ca(2+) handling. In previous studies we characterized an erythrocyte Ca(2+) influx, sensitive to membrane potential and inhibited by Ca(2+) antagonists. Since its maximal influx rate was decreased in HD patients, this study investigates if Ca(2+) influx alterations are related to myocardial disorders in HD patients. METHODS: Voltage-sensitive erythrocyte Ca(2+) influx was measured in 30 healthy controls and in 53 patients (47 HD patients and six patients with left ventricular hypertrophy and normal kidney function), using fura 2. In 29 HD patients and in six healthy subjects Ca(2+) influx was also determined in the presence of parathyroid hormone (PTH) in vitro. Patients were classified according to Lown's ventricular arrhythmias classification after 24-h Holter electrocardiograph (ECG) monitoring. Forty-six patients underwent echocardiography. RESULTS: Voltage-sensitive erythrocyte Ca(2+) influx was significantly reduced in HD patients. Maximal influx rate was significantly higher in HD patients of Lown's classes 3 and 4 (0.789 +/- 0.156 nmol/s, n = 8; P < 0.01) than in patients of classes 1 and 2 (0.499 +/- 0.055 nmol/s, n=15), or without ventricular arrhythmias (0.400 +/- 0.041 nmol/s, n = 24). Maximal influx rate was directly correlated to left ventricular mass index (LVM) (r = 0.353, P < 0.05). Subjects with left ventricular hypertrophy and normal kidney function displayed erythrocyte Ca(2+) influx similar to that of normal subjects. Multiple regression indicates that LVM and Ca(2+) influx were independently related to severity of arrhythmias. When added to the influx assay, PTH increased the maximal influx rate only in patients with ventricular arrhythmias. CONCLUSION: Myocardial dysfunction and altered ventricular excitability could be related in uraemic HD patients to alterations of calcium transport, as found in the erythrocyte model. Reduced resistance to PTH could contribute to this phenomenon.

Choroidal calcifications in patients with Gitelman's syndrome.

Gitelman's syndrome is a renal tubular disorder characterized by a sodium and chloride reabsorption defect in distal tubular cells that determines hypokalemia, metabolic alkalosis, hypomagnesemia, and low calcium excretion. The presence of choroidal calcifications was sought in five patients with Gitelman's syndrome by ophthalmic examination, fluorescein angiography, indocyanine green angiography, and ocular ultrasonography. Calcifications observed in the choroid of two patients were shown by ultrasonography in both patients. Ophthalmic and fluorangiographic examinations detected this alteration in one of the two subjects. Chondrocalcinosis was found in one patient with choroidal calcifications. These findings suggest that precipitation of calcium salts can occur in the choroidal tissue of patients with Gitelman's syndrome. Deposits appeared to be well seen by ultrasonography because of their depth in ocular tissues. Sclerochoroidal calcifications may be favored by the low calcium excretion, which is associated with normal intestinal calcium absorption in patients with Gitelman's syndrome.

Chloride fluxes activated by parathyroid hormone in human erythrocytes.

We used the chloride fluorescent probe, 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ), to study chloride fluxes in human erythrocytes. The SPQ load was made by hypotonic buffer (150 mOsm, 10 min). Intracellular fluorescence was monitored continuously at 360 nm excitation and 410 nm emission wavelengths. The leakage of SPQ out of cells was <5% h(-1) and the Stern-Volmer constant for quenching of intracellular SPQ by Cl was 0.023 mM(-1). The time course of intracellular [Cl] was measured and the influence of PTH, forskolin, and phorbol 12-myristate 13-acetate (PMA) on erythrocyte Cl transport was examined. The results establish a direct method to measure intracellular [Cl] continuously in erythrocytes and show that PTH induces a Cl efflux inhibited by 4, 4'-diisothiocyanatostilbene-2,2'-disulfonate. This effect was similar to those induced by forskolin, which stimulates cAMP generation, and by PMA, which stimulates protein kinase C.