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E Massa

Publications and source records attributed to E Massa.

At least 19 recordsLinked to original sources
PubMed2001

Serum values of proinflammatory cytokines are inversely correlated with serum leptin levels in patients with advanced stage cancer at different sites.

Leptin is a recently identified hormone produced by the adipocyte ob gene which acts as a negative feedback signal critical to the normal control of food intake and body weight. A number of proinflammatory cytokines, such as interleukin 6, tumor necrosis factor alpha, and interferon gamma, have been proposed as mediators of cancer cachexia; these data suggest that abnormalities in leptin production/release or in its feedback mechanism play a role in cancer patients. We therefore studied the relationship between serum leptin and serum cytokines interleukin 6 and tumor necrosis factor alpha levels in advanced-stage cancer patients. Twenty-nine advanced stage cancer patients (all but one stage IV) with tumors at various sites were included in the study. A direct correlation between body mass index and serum leptin levels was found both in cancer patients and in healthy individuals. The serum levels of interleukin 6 were significantly higher in cancer patients than in healthy individuals. In cancer patients an inverse correlation was found between serum levels of leptin and proinflammatory cytokines. There was an inverse correlation between the Eastern Cooperative Oncology Group performance status scale and serum levels of leptin. Regarding survival, patients with very high serum levels of proinflammatory cytokines and very low levels of leptin had very short survival. Although obtained in a cancer patient population not overtly cachectic, our results provide further evidence that a simple dysregulation of leptin production and/or release cannot be involved in cancer-associated pathophysiological changes leading to cachexia.

Adult↗
PubMed2001

Docetaxel and cisplatin in locally advanced or metastatic squamous-cell carcinoma of the head and neck: a phase II study of the Southern Italy Cooperative Oncology Group (SICOG).

BACKGROUND: Docetaxel is one of the most promising new drugs against squamous-cell carcinoma of the head and neck (SCCHN), while cisplatin is one of the most active single agents. A phase I study has shown the feasibility of the combination of the two drugs, and activity in SCCHN has been seen. PATIENTS AND METHODS: Patients with locally advanced, inoperable, or metastatic SCCHN, never pretreated with radiotherapy or chemotherapy, received three courses of docetaxel 75 mg/m2 and cisplatin 100 mg/m2, every three weeks. Thereafter, responsive metastatic patients received additional chemotherapy, while patients with locally advanced disease underwent radiation therapy. RESULTS: Forty-six patients (forty-five with locally advanced, one with metastatic disease) were entered into the study. Ten patients did not complete three courses of chemotherapy because of early death; one patient discontinued treatment after one course. Twenty-one objective responses were observed (46%, 95% confidence interval (CI): 31%-60%), including five complete responses (11%) and sixteen partial responses (35%). Following induction chemotherapy plus radiation therapy, 9 of 21 evaluable patients were rendered disease free, while 8 additional patients had a partial response. After a median follow-up of 18 months, the median duration of response was 12 months, (range 3-25+), and the median overall survival was 11 months. Six early deaths were considered possibly treatment-related (sepsis following grade 4 neutropenia in two cases, hypovolemic shock following severe diarrhea in four cases). Neutropenia was the most severe toxicity (grade 3-4 in 28 patients, median duration 4 days); diarrhea and vomiting were the most troublesome non-haematologic toxicities (grade 4 in 4 and 3 patients, respectively). CONCLUSIONS: The combination of docetaxel and cisplatin is active in SCCHN, but toxicity is substantial. This schedule does not appear to offer any advantage compared with conventional regimens.

Adult↗
PubMed2001

Managing cancer-related anorexia/cachexia.

Cancer-related anorexia/cachexia (CAC) is a complex phenomenon in which metabolic abnormalities, proinflammatory cytokines produced by the host immune system, circulating tumour-derived catabolic factors, decreased food intake, and probably additional unknown factors, all play different roles. This review examines the mechanisms of CAC and its management. All the potential modalities of intervention from nutritional to pharmacological approaches are included with a clear distinction between unproven, investigational and well established treatments. Among the latter, the progestogens are currently considered the most effective and safest drugs for the management of CAC. Agents currently under investigation for CAC include thalidomide, pentoxifylline and melatonin, which most probably act on cytokine release, and clenbuterol, which acts on muscle mass and to antagonise protein wasting. Our personal experience with the synthetic progestogens megestrol and medroxyprogesterone supports their use as first-line agents. In addition, our work on the potential role of antioxidant agents in counteracting the oxidative stress, which appears to be involved in CAC, shows them to be promising agents when used in combination chemotherapy regimens either alone or with other 'biologics'. There is an ongoing need for quality of life questionnaires which specifically address the most significant symptoms present in patients with CAC.

Adrenal Cortex Hormones↗
PubMed2001

Immunotherapy (recombinant interleukin 2), hormone therapy (medroxyprogesterone acetate) and antioxidant agents as combined maintenance treatment of responders to previous chemotherapy.

An open, non-randomized phase II study was carried out including all patients treated with whatever chemotherapy or combined modality regimen for whatever cancer who were in clinical objective response or stable disease (SD) for more than three months, to receive maintenance treatment with recombinant interleukin-2 (rIL-2) plus medroxyprogesterone acetate (MPA) plus antioxidant agents alpha-lipoic acid (ALA) and N-acetyl cysteine (NAC). The main study endpoints were clinical outcome and toxicity. The secondary endpoints were effects of treatment on cancer-related anorexia/cachexia syndrome (CACS) symptoms, on serum levels of proinflammatory cytokines, IL-2, C-reactive protein (CRP) and leptin as well as the evaluation of quality of life (QL). rIL-2 was administered at a dose of 1.8 MIU subcutaneously three times/week on alternate days for the first two weeks of every month and MPA was given orally at a dose of 500 mg once a day at alternate days without interruption. ALA 300 mg/day orally and NAC 1800 mg/day orally were also administered. The treatment was administered until progression of disease or appearance of toxicity. From July 1998 to May 2000, 16 patients were enrolled in the study (M/F ratio: 15/1; mean age: 62 years, range 45-71). The median duration of maintenance treatment was 10 months (range 5-22). The response to maintenance treatment at September 2000 was: CR (persistent throughout the treatment) 4 patients (25%); SD 1 patient (6.2%); PD 11 patients (68.8%). The median duration of response was 9.8 months (range: 5-22+). The median follow-up duration was 19 months (range: 8-102). The median OS was not reached. The median PFS was 14 months (range 1-29). The 1-year survival rate was 25%. At September 2000, 9 patients are still surviving. No grade 3/4 toxicity was observed. One Grade 2 skin toxicity was observed and Grade 1: 2 fever, 2 thrombocytopenia, 1 neutropenia and 1 skin were observed. The ECOG PS did worsen significantly, the body weight and BMI increased significantly after treatment, whereas the appetite did not change significantly. The QL evaluation showed a significant amelioration of cognitive functions and a borderline significant amelioration of emotional functions after treatment, whereas a borderline worsening of dyspnea was observed. The absolute lymphocyte count increased significantly after the maintenance treatment, as well as the serum IL-2, TNFalpha decreased at borderline statistical significance; the serum levels of leptin did not change significantly. The evaluation of patient subgroups showed that responders/survivors had a pattern superimposable to that of whole patient population, the patients who rapidly progressed and died exhibited no significant changes of these parameters during treatment. The results of the present study suggest that the host immune response, evaluated by several parameters, after IL-2 administration, (e.g. lymphocytosis), are worth further study as potential markers for the major end points of cancer treatment, i.e. OS and QL, in an adequate number of patients.

Aged↗
PubMed2000

Restoration of functional defects in peripheral blood mononuclear cells isolated from cancer patients by thiol antioxidants alpha-lipoic acid and N-acetyl cysteine.

The ability of Alpha-Lipoic Acid (ALA) and N-Acetyl Cysteine (NAC), two active antioxidant agents, to correct in vitro the most significant functional defects of peripheral blood mononuclear cells (PBMC) isolated from advanced stage cancer patients was studied. The proliferative response of PBMC isolated from cancer patients to anti-CD3 monoclonal antibody (MAb) and the expression of CD25 (IL-2R) and CD95 (Fas) on unstimulated and anti-CD3 MAb-stimulated PBMC were studied, and the serum levels of proinflammatory cytokines IL-1, IL-6, TNFalpha as markers of pro-cachectic activity in cancer patients, and the serum levels of IL-2 and sIL-2R were assessed. Twenty patients (mean age 64.6 years) with cancer of lung, ovary, endometrium, and head and neck, all in advanced (III, IV) stage of disease, were studied. The serum levels of IL-1beta, IL-2, IL-6, TNFalpha, and sIL-2R were significantly higher in cancer patients than in normal subjects. The response of PBMC isolated from cancer patients to anti-CD3 MAb was significantly lower than that of controls. The addition of either ALA 0.001 mM or NAC 0.004 mM in the PBMC cultures stimulated with anti-CD3 MAb significantly increased the response of PBMC isolated from cancer patients and normal subjects. After 24 and 72 hr of culture with anti-CD3 MAb, the expression of CD25 and CD95 on PBMC isolated from cancer patients was significantly lower than that of PBMC isolated from normal subjects. The addition of either ALA or NAC into cultures of PBMC isolated from cancer patients significantly increased the percentage of cells expressing CD25 as well as those expressing CD95. The results of the present study show a favorable effect of antioxidant agents ALA and NAC on several important T-cell functions in vitro in advanced-stage cancer patients.

Acetylcysteine↗
PubMed2000

Serum levels of leptin and proinflammatory cytokines in patients with advanced-stage cancer at different sites.

Leptin is a recently identified hormone produced by the adipocyte ob gene which acts as a negative feedback signal critical to the normal control of food intake and body weight. A number of proinflammatory cytokines, such as interleukin (IL) 1alpha, IL-6, tumor necrosis factor (TNF) alpha and interferon (IFN) gamma, have been proposed as mediators of cancer cachexia. These data suggest that abnormalities in leptin production/release or in its feedback mechanism play a role in cancer patients. To elucidate this we studied the relationship between total serum leptin and serum cytokines IL-1alpha, IL-6, TNFalpha as well as the production of leptin and cytokines by peripheral blood mononuclear cells (PBMC) isolated from cancer patients. Sixteen advanced cancer patients (mainly stage IV) with tumors at different sites were included in the study. The serum levels of leptin in cancer patients were significantly lower than those of healthy individuals at all times (7 a.m., noon, 3 p.m.). No significant differences were found in circadian rhythm between patients and controls. Serum levels of IL-1alpha, IL-6, and TNFalpha were significantly higher in cancer patients than in healthy individuals. An inverse correlation between serum levels of leptin and IL-6 was found in cancer patients. The production in culture of leptin by unstimulated PBMCs and those stimulated by phytohemagglutinin M or by phorbol myristate acetate isolated from cancer patients was very low; no differences were observed in comparison with leptin production by PBMCs from healthy individuals.

Adult↗
PubMed2000

Phase II study of induction chemotherapy followed by concomitant chemoradiotherapy in advanced head and neck cancer: clinical outcome, toxicity and organ/function preservation.

The purpose of the study was to assess response rate, clinical outcome, organ/function preservation and toxicity in head and neck cancer patients treated with induction chemotherapy followed by concomitant chemoradiotherapy and, when necessary, limited surgery. The study design was a phase II non-randomized trial in hospitalized patients setting. The treatment plan consisted of 3 cycles of induction chemotherapy with cisplatin, fluorouracil (5-FU), leucovorin and interferon alpha2b (PFL-IFN) followed by 7 cycles of 5-FU, hydroxyurea and concomitant radiation for 5 days (FHX) for a total radiation dose of 70 Gy. Surgical resection was performed, when necessary, with the intent to spare organ/function. Seventeen patients were treated at one institution. Three patients had stage III and 14 patients stage IV disease. Twelve patients were analyzed for response to PFL-IFN: 2/12 (16.7%) patients achieved a CR and 10/12 (83.3%) achieved a PR for an ORR of 100%. FHX was administered on protocol to 10 patients: 4 patients (40%) had CR, 3 (30%) had PR >/=70% for an ORR of 70%, 1 patient (10%) had SD and 2 patients (20%) had PD. As for local therapy, of the 8 eligible patients who completed chemoradiotherapy, the 3 patients with CR were submitted to random biopsies, results of which were histologically negative, 3 patients with PR >/=70% underwent conservative organ-preserving surgery, and 1 patient with PR >70% refused surgery, whereas the patient with SD underwent salvage surgery, preserving voice. Thus, organ preservation was achieved in all 8 patients at the completion of all therapy: 4 patients had no surgical procedure and 4 patients only conservative surgery. Overall, after completion of all therapy, 5/8 (62.5%) patients were rendered disease-free. The median overall survival time was 23 months, the median duration of response was 6 months and the median time to progression was 9 months. Both induction chemotherapy and concomitant chemoradiotherapy resulted in significant toxicity, which consisted mainly of mucositis and thrombocytopenia. In conclusion, PFL-IFN was very active, producing high ORRs and, followed by FHX, resulted in high overall survival rates permitting an optimal organ preservation, at the cost of a severe toxicity.

Adult↗
PubMed1999

Phosphorylation-dependent inhibition of protein phosphatase-1 by G-substrate. A Purkinje cell substrate of the cyclic GMP-dependent protein kinase.

G-substrate, a specific substrate of the cGMP-dependent protein kinase, has previously been localized to the Purkinje cells of the cerebellum. We report here the isolation from mouse brain of a cDNA encoding G-substrate. This cDNA was used to localize G-substrate mRNA expression, as well as to produce recombinant protein for the characterization of G-substrate phosphatase inhibitory activity. Brain and eye were the only tissues in which a G-substrate transcript was detected. Within the brain, G-substrate transcripts were restricted almost entirely to the Purkinje cells of the cerebellum, although transcripts were also detected at low levels in the paraventricular region of the hypothalamus and the pons/medulla. Like the native protein, the recombinant protein was preferentially phosphorylated by cGMP-dependent protein kinase (Km = 0.2 microM) over cAMP-dependent protein kinase (Km = 2.0 microM). Phospho-G-substrate inhibited the catalytic subunit of native protein phosphatase-1 with an IC50 of 131 +/- 27 nM. Dephospho-G-substrate was not found to be inhibitory. Both dephospho- and phospho-G-substrate were weak inhibitors of native protein phosphatase-2A1, which dephosphorylated G-substrate 20 times faster than the catalytic subunit of protein phosphatase-1. G-substrate potentiated the action of cAMP-dependent protein kinase on a cAMP-regulated luciferase reporter construct, consistent with an inhibition of cellular phosphatases in vivo. These results provide the first demonstration that G-substrate inhibits protein phosphatase-1 and suggest a novel mechanism by which cGMP-dependent protein kinase I can regulate the activity of the type 1 protein phosphatases.

Amino Acid Sequence↗
PubMed1998

Neo-adjuvant chemo-(immuno-)therapy of advanced squamous-cell head and neck carcinoma: a multicenter, phase III, randomized study comparing cisplatin + 5-fluorouracil (5-FU) with cisplatin + 5-FU + recombinant interleukin 2.

We carried out an open, randomized, phase III, multicenter clinical trial to compare, in neo-adjuvant setting, the clinical response and toxicity of the combination chemotherapy cisplatin + 5-FU with the same combination plus s.c. recombinant interleukin-2 (rIL-2) in patients with advanced (stage III IV) head and neck squamous-cell carcinoma (HNSCC). Regimen A was the classical Al Sarraf treatment: 100 mg/m2 cisplatin i.v. on day 1 plus 1000 mg m(-2) day(-1) 5-FU on days 1-5 as a continuous infusion. Regimen B was the same as regimen A plus 4.5 MIU/day rIL-2 s.c. on days 8-12 and 15-19. Treatment was repeated every 3 weeks for three cycles. A total of 33 patients were enrolled in the study; 30 were evaluable for toxicity and 28 for response. Seventeen patients were assigned to group A and 16 were assigned to group B. Three patients (20%) of group A and 4 (31%) of group B had a complete response, 9 patients (60%) of group A and 6 (46%) of group B had a partial response, with an overall response rate of 12 patients (80%) for group A and 10 patients (77%) for group B. Two patients (13%) of group A and 3 patients (23%) group B had stable disease; 1 patient (7%) of group A had progressive disease. Thus, there was not a statistically significant difference in response rate between the two groups and therefore there was no benefit from the addition of immunotherapy with rIL-2 to the standard chemotherapy. Both regimens were well tolerated. There were 2 toxic deaths (6.7%), 1 from hematological causes in group A and I from cardiac causes in group B. Myelosuppression and gastrointestinal toxicity, mainly nausea/vomiting and stomatitis, were the most frequent toxicities. The calculated number of patients for the sample has not yet been reached; however, the projection of our present results suggests that it is highly improbable that a clinically significant difference between the two treatment groups will be observed even if the calculated patient sample size is achieved.

Adult↗
PubMed1998

Cytokine involvement in cancer anorexia/cachexia: role of megestrol acetate and medroxyprogesterone acetate on cytokine downregulation and improvement of clinical symptoms.

The characteristic clinical picture of anorexia, tissue wasting, loss of body weight accompanied by a decrease in muscle mass and adipose tissue, and poor performance status that often precedes death has been named the cancer-related anorexia/cachexia syndrome (CACS). Chronic administration of pro-inflammatory cytokines, including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF) either alone or in combination, is capable of reproducing the different features of CACS. High serum levels of these cytokines have been found in cancer patients, which seem to correlate with progression of the tumor. This paper describes a series of experimental and clinical studies demonstrating that: (1) high serum levels of some cytokines, including IL-1, IL-6, and TNF, are present in advanced-stage cancer patients, particularly those with CACS; (2) megestrol acetate (MA) has a beneficial therapeutic effect on CACS symptoms, such as appetite, body weight, and quality-of-life; (3) MA downregulates the synthesis and release of cytokines and relieves the symptoms of CACS; (4) cytokines play a key role in the onset of CACS; (5) medroxyprogesterone acetate (MPA) reduces the in vitro production of cytokines and serotonin (5-hydroxytryptamine, 5-HT) by peripheral blood mononuclear cells (PBMC) of cancer patients; and (6) MA and MPA reduce the cisplatin-induced 5-HT release in vitro from PBMC of cancer patients. Based on these results, a clinical study incorporating MA/MPA in combination with chemotherapy or chemoimmunotherapy may be warranted.

Anorexia↗
PubMed1998

Cytokine activity in cancer-related anorexia/cachexia: role of megestrol acetate and medroxyprogesterone acetate.

The characteristic clinical picture of anorexia, tissue wasting, loss of body weight accompanied by a decrease in muscle mass and adipose tissue, and poor performance status that often precedes death has been named the cancer-related anorexia/cachexia syndrome (CACS). Chronic administration of pro-inflammatory cytokines, including interleukin-I (IL-I), IL-6, and tumor necrosis factor (TNF), either alone or in combination, is capable of reproducing the different features of CACS. High serum levels of these cytokines have been found in cancer patients, which seem to correlate with progression of the tumor. This article describes a series of experimental and clinical studies demonstrating that: (1) high serum levels of some cytokines, including IL-I, IL-6, and TNF, are present in advanced-stage cancer patients, particularly those with CACS; (2) megestrol acetate (MA) has a beneficial therapeutic effect on CACS symptoms, such as appetite, body weight, and quality of life; (3) MA downregulates the synthesis and release of cytokines and relieves the symptoms of CACS; (4) cytokines play a key role in the onset of CACS; (5) medroxyprogesterone acetate (MPA) reduces the in vitro production of cytokines and serotonin (5-hydroxytryptamine, 5-HT) by peripheral blood mononuclear cells (PBMC) of cancer patients; and (6) MA and MPA reduce the cisplatin-induced 5-HT release in vitro from PBMC of cancer patients. Based on these results, a clinical study incorporating MA/MPA in combination with chemotherapy or chemoimmunotherapy may be warranted. In addition, it has been recently shown that "oxidative stress" resulting from reactive oxygen species, which can be induced by pro-inflammatory cytokines, is involved in tissue wasting and CACS. These results suggest promising approaches for the prevention and treatment of cytokine-induced CACS based on MA, MPA, and metabolic antioxidants.

Anorexia↗
PubMed1997

Tumor-associated lympho-monocytes from neoplastic effusions are immunologically defective in comparison with patient autologous PBMCs but are capable of releasing high amounts of various cytokines.

We studied several in vitro activities of tumor-associated lympho-monocytes (TALMs) and the concentrations of interleukin (IL)-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)alpha, interferon (IFN)gamma and soluble IL-2 receptor (slL-2R) in neoplastic effusions and in the serum of advanced stage cancer patients. Comparisons were made with autologous peripheral blood mononuclear cells (PBMCs). Autologous PBMCs were compared with PBMCs from normal subjects used as controls. TALMs were collected from 13 peritoneal and 18 pleural neoplastic effusions, secondary to primary tumors of different sites. After PHA stimulation, concentrations of IL-1alpha, IL-1beta and TNF alpha in culture media of TALMs both from peritoneal and pleural effusions were lower than those of autologous PBMCs and, similarly, concentrations of IL-4 and IL-10 in culture media of TALMs from peritoneal effusions were lower than those of autologous PBMCs, whereas concentrations of IL-4 and IL-10 in culture media of TALMs from pleural effusions were in the same range as those of autologous PBMCs. On the contrary, IL-2, IL-6 and IFN gamma amounts (only from pleural effusions) were significantly higher. IL-1alpha, IL-1beta, IL-2, IL-6 and TNF alpha production from patient PBMCs was lower than that of control PBMCs, whereas production of IL-4, IL-10 and IFN gamma was higher than that of control PBMCs. Both in peritoneal and in pleural effusions concentrations of IL-1alpha, IL-1beta and IL-4 were not different from those measured in autologous serum, whereas those of IL-6, IL-10, TNF alpha, IFN gamma and sIL-2R were significantly higher. The amounts of IL-2 in pleural effusions were not different from those of autologous serum, but in peritoneal effusions they were higher than those of autologous serum. The amounts of IL-1alpha, IL-1beta, IL-2, IL-6, TNF alpha and sIL-2R were higher in patient than in control sera, whereas those of IL-4, IL-10 and IFN gamma were in the same range in patient and in control sera. Cell cycle analysis of cultured TALMs and PBMCs (from 3 patients) showed a significant accumulation of TALMs in the non-cycling G0/G1 cell population compared with autologous PBMCs.

Aged↗
PubMed1997

Medroxyprogesterone acetate reduces the in vitro production of cytokines and serotonin involved in anorexia/cachexia and emesis by peripheral blood mononuclear cells of cancer patients.

Medroxyprogesterone acetate (MPA) is widely used in oncology both in the treatment of hormone-related cancers and as supportive therapy in anorexia/cachexia syndrome (ACS), but conclusive data are not yet available to explain its anticachectic effect. ACS is characterised by weight loss, changes in metabolism, reduction of appetite, nausea and vomiting. Several cytokines, mainly interleukin (IL)-1, IL-2, IL-6 and tumour necrosis factor alpha (TNF alpha), are involved in the pathogenesis of ACS. Additionally, nausea and vomiting can be mediated by factors inducing serotonin (5-HT) production and/or release by pleiotropic cells including activated T lymphocytes. In the present study, we report the effect of MPA on peripheral blood mononuclear cells (PBMC) from 10 cancer patients in advanced stage of disease (6 head and neck, 2 colon, 1 lung and 1 ovary). The proliferative response of PBMC to PHA, anti-CD3 monoclonal antibody (MAb) or recombinant IL-2 (rIL-2), the production of IL-1 beta, IL-2, IL-6, TNF alpha and 5-HT by PHA-stimulated PBMC and the expression of lymphocyte membrane-bound IL-2 receptor (IL-2R) subunities (CD25 and CD122) were studied. The addition of MPA significantly reduced the PBMC proliferative response to PHA and anti-CD3 MAb but not to rIL-2. MPA 0.2 microgram/ml was also capable of reducing the levels of IL-1 beta, IL-6, TNF alpha and 5-HT produced in culture by PHA-stimulated PBMC, whereas it did not induce any change in the percentage of PBMC expressing either CD25 or CD122 or both molecules after stimulation with PHA or anti-CD3 mAb.

Aged↗
PubMed1995

Comparison of fura-2 imaging and electrophysiological analysis of murine calcium channel alpha 1 subunits coexpressed with novel beta 2 subunit isoforms.

A polymerase chain reaction product was used to isolate mouse brain cDNA clones coding for isoforms of the beta subunit of voltage-dependent Ca2+ channels. The two mouse brain beta 2 subunit cDNA clones described, beta 2a and beta 2b, differed by alternative splicing within the coding region but possessed a unique amino terminus not yet reported in other beta 2 subunit cDNAs. Northern blot and RNase protection analyses demonstrated that both mRNA isoforms could be detected in highest abundance in heart and brain and at lower levels in lung, kidney, and testis. In a novel assay for beta 2 subunit function, COS-1 cells were transfected with alpha 1 and beta 2 subunit expression vectors and assayed for increases in intracellular Ca2+ concentration by using fura-2 imaging. Co-transfection of COS-1 cells with the mouse brain class C-1 alpha 1 subunit expression vector and either of the beta 2 subunit expression vectors resulted in increases in intracellular Ca2+ concentration after stimulation with elevated K+ and the dihydropyridine agonist Bay K 8644. Transfection of either alpha 1 or beta 2 subunit expression vectors alone did not result in an elevation of intracellular Ca2+ concentration. Electrophysiological recording of human embryonic kidney 293 cells transfected with the expression vector for the alpha 1 subunit alone or with either beta 2 subunit demonstrated expression of voltage-dependent Ca2+ channels that were dihydropyridine sensitive. Currents formed by expression of only the alpha 1 subunit were small and slowly inactivated. In contrast, the currents formed by coexpression of alpha 1 subunits with either beta 2 subunit were larger and inactivated more rapidly. Dihydropyridine binding studies demonstrated that coexpression of alpha 1 subunits with beta 2 subunits increased the density of functional receptors, compared with expression of alpha 1 subunits alone. These experiments suggested that coexpression of the alpha 1 and beta 2 subunits produced functional dihydropyridine-sensitive Ca2+ channels and that both beta subunit isoforms had modulatory effects on these channels.

Amino Acid Sequence↗
PubMed1994

Genetic alteration of cyclic adenosine 3',5'-monophosphate-dependent protein kinase subunit expression affects calcium currents and beta-endorphin release in AtT-20 clonal pituitary cells.

The role of the cAMP-dependent kinase (AK) in neurotransmission was investigated by genetic alteration of AK subunit expression in AtT-20 clonal pituitary cells. We characterized and compared wild-type [AK(wt)] cells and two clones with different AK activities. The first stably expresses a gene for a mutant AK regulatory subunit (RI) that does not bind cAMP [AK(-)]; the second stably expresses a gene for the catalytic subunit (C) of AK [AK(+)]. Western blot analysis of RI and C subunit expression showed increased expression of both subunits in AK(+) and AK(-) cells relative to AK(wt), with the transfection-induced expression of one subunit producing a compensatory increase in the expression of the other. The basal AK activities varied among the cell types, with AK(+) cells possessing 3-fold higher basal AK activity than AK(wt) cells, and AK(-) cells possessing half the AK activity of AK(wt) cells. Preincubation of cultures with 300 microM 8-(4-chlorophenylthio)-cAMP increased AK activity approximately 4-fold in AK(wt) and AK(+) cells, but was without effect in AK(-) cells. Subsequent addition of 1 microM cAMP in vitro increased AK activity an additional 2- to 3-fold in all cell types. The higher basal AK activity found in AK(wt) and AK(+) cells was associated with larger whole cell calcium currents (approximately 43% and approximately 75% larger than in AK(-) cells, respectively) and faster rates of current rundown. The currents from each cell line had similar voltage-dependent and pharmacological properties, however, and [3H]PN200-110 binding was similar among the cell types. Maximal currents were evoked at clamp potentials of 0-10 mV; currents were inactivated approximately 30% in the steady state at holding potentials of -40 mV compared to -80 mV, and currents were reduced approximately 45% in the presence of nifedipine at -40 mV, but were insensitive to omega-conotoxin GVIA. AK(wt) and AK(+) cells also had higher basal and cAMP-stimulated release of beta-endorphin; control rates were approximately 50% greater, but stimulated rates were approximately 400% greater compared to those in AK(-) cells. We conclude that a greater number of calcium channels were activated by depolarization in the phosphorylated state, that current rundown was largely due to dephosphorylation, and that activation of calcium channels was coupled to the release of beta-endorphin.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropic Hormone↗
PubMed1993

Evidence that the hormone binding domain of steroid receptors confers hormonal control on chimeric proteins by determining their hormone-regulated binding to heat-shock protein 90.

Previously, it has been shown that the hormone binding domain of the glucocorticoid receptor acts as a transferable regulatory cassette that can confer hormonal control onto chimeric proteins [Picard, D., Salser, S. J., & Yamamoto, K. R. (1988) Cell 54, 1073-1080]. The hormone binding domain of the glucocorticoid receptor contains its site of interaction with the 90-kDa heat-shock protein, hsp90 [Dalman, F. C., Scherrer, L. C., Taylor, L. P., Akil, H., & Pratt, W. B. (1991) J. Biol. Chem. 266, 3482-3490]. We have now transfected COS cells with cDNAs for fusion proteins containing beta-galactosidase and portions of the glucocorticoid receptor, and we demonstrate a correlation between hormone regulation of fusion protein localization and binding of the fusion proteins to hsp90. The hormone binding domain (residues 540-795) of the rat glucocorticoid receptor is sufficient for conferring hormone regulation onto a fusion protein and for intracellular binding of a fusion protein to hsp90. The hormone binding domain of the rat glucocorticoid or the human estrogen receptor is also sufficient to permit reticulocyte lysate-mediated refolding of a fusion protein into association with hsp90. Consistent with the results of fusion protein localization in intact cells, binding of a fusion protein to hsp90 blocks binding of antibody directed against the NL1 nuclear localization signal of the glucocorticoid receptor. These observations argue strongly that the hormone binding domain of the glucocorticoid receptor confers hormonal control of fusion proteins by conferring hormone-regulated binding to hsp90.

Animals↗
PubMed1993

Automatic analysis of high resolution atrial activation in mitral valve stenosis.

High resolution P-waves of 28 patients having a mean age of 45 years and affected by isolated mitral valve stenosis (nine of whom showed paroxysmal atrial fibrillation) have been compared with those obtained from 30 healthy subjects about 35 years old. Our primary aim was to characterize the signal-averaged P-wave in mitral valve stenosis. Parameters which differed between the two groups in time domain analysis were the P-wave duration, the abscissa of the maximum positive voltage amplitude, the peak-to-peak amplitude and the integrated voltage-time product, which turned out to be greater in the patient class than in the healthy set; furthermore, in the frequency domain analysis, amplitudes in the range from 37 to 60 Hz were greater in healthy subjects than in patients. A successive analysis carried out to predict those patients with mitral valve stenosis who are at risk of developing paroxysmal atrial fibrillation showed that the P-wave duration and the amplitudes (in the range 60-106 Hz) were the most distinctive parameters, but, unfortunately, without any significant difference with respect to those of patients with mitral valve stenosis alone. Finally, some correlations between the age, the P-wave duration and the left atrial diameter of patients, were revealed to exist only in patients affected by episodes of atrial fibrillation.

Adult↗