A holistic approach to prostate cancer treatment: natural products as enhancers to a medically minded approach.

Prostate cancer (PC) has historically been the most diagnosed cancer in men. Though treatment for prostate cancer is often effective, it is also often very taxing on the body and commonly has negative quality of life implications. One such example is androgen suppression therapy (AST), which has severe side effects that can be mitigated through physical activity. Natural agents and protocols are increasingly studied for their merit against cancer and for their potential to treat cancer in ways that preserve the quality of life. Many agents and lifestyle choices have been shown to have success against prostate cancer. There is promising evidence that simple treatments such as green tea, pomegranate, and a regular exercise routine can be effective against prostate cancer. These treatments have the potential to enhance current treatment protocols. In this review, we will discuss the viability of many natural agents as treatments for prostate cancer and its complications.

IL-32 and its paradoxical role in neoplasia.

Interleukin-32 (IL-32) is an interleukin cytokine usually linked to inflammation. In recent years, it has been found that IL-32 exhibits both pro- and anti-tumor effects. Although most of those effects from IL-32 appear to favor tumor growth, some isoforms have shown to favor tumor suppression. This suggests that the role of IL-32 in neoplasia is very complex. Thus, the role of IL-32 in these various cancers and protein pathways makes it a very crucial component to consider when looking at potential therapeutic options in tumor treatment. In this review, we will explore what is currently known about IL-32, including its relationship with tumorigenesis and the potential for IL-32 to enhance local and systemic anti-tumor immune responses. Such a study might be helpful to accelerate the development of IL-32-based immunotherapies.

Anti-inflammatory medication use associated with reduced delirium risk and all-cause mortality: A retrospective cohort study.

OBJECTIVE: To investigate the relationship between history of anti-inflammatory medication use and delirium risk, as well as long-term mortality. METHODS: In this retrospective cohort study, subjects recruited between January 2016 and March 2020 were analyzed. Information about anti-inflammatory medication use history including aspirin, NSAIDs, glucosamine, and other anti-inflammatory drugs, was collected. Logistic regression analysis investigated the relationship between anti-inflammatory medications and delirium. Log-rank analysis and cox proportional hazards model investigated the relationship between anti-inflammatory medications and one-year mortality. RESULTS: The data from 1274 subjects were analyzed. The prevalence of delirium was significantly lower in subjects with NSAIDs usage (23.0%) than in those without NSAIDs usage (35.0%) (p < 0.001). Logistic regression analysis controlling for age, sex, dementia status, and hospitalization department showed that the risk of delirium tended to be reduced by a history of NSAIDs use (OR, 0.76 [95% CI, 0.55 to 1.03]). The one-year mortality in the subjects with NSAIDs (survival rate, 0.879 [95% CI, 0.845 to 0.906]) was significantly lower than in the subjects without NSAIDs (survival rate, 0.776 [95% CI, 0.746 to 0.803]) (p < 0.001). A history of NSAIDs use associated with the decreased risk of one-year mortality even after adjustment for age, sex, Charlson Comorbidity Index, delirium status, and hospitalization department (HR, 0.70 [95% CI, 0.51 to 0.96]). CONCLUSION: This study suggested that NSAIDs usage was associated with decreased delirium prevalence and lower one-year mortality. The potential benefit of NSAIDs on delirium risk and mortality were shown.

The past, present, and future of immunotherapy for colorectal cancer.

Colorectal cancer is prevalent worldwide, with various factors influencing the survival rate of late-stage metastatic cases. Current standard treatments include surgical removal, adjuvant chemotherapy, and neoadjuvant chemotherapy. Novel immunotherapy research shows promising results for various cancer types, including colorectal cancer. Current immunotherapy options are limited to specific molecular subtypes of colorectal cancer, while the remaining are limited to standard protocol. This review article summarizes approved, developing, and potential sources for novel colorectal cancer immunotherapy treatment through active-specific, checkpoint inhibitor, cytokine, cytotoxic, and adoptive T-cell immunotherapy. Such a study would be beneficial to patients with colorectal cancer.

The genome-wide DNA methylation profiles among neurosurgery patients with and without post-operative delirium.

AIMS: There is no previous study demonstrating the differences of genome-wide DNA methylation (DNAm) profiles between patients with and without postoperative delirium (POD). We aimed to discover epigenetic (DNAm) markers that are associated with POD in blood obtained from patients before and after neurosurgery. METHODS: Pre- and post-surgical blood DNA samples from 37 patients, including 10 POD cases, were analyzed using the Illumina EPIC array genome-wide platform. We examined DNAm differences in blood from patients with and without POD. Enrichment analysis with Gene Ontology and Kyoto Encyclopedia of Genes and Genomes terms were also conducted. RESULTS: When POD cases were tested for DNAm change before and after surgery, enrichment analyses showed many relevant signals with statistical significance in immune response related-pathways and inflammatory cytokine related-pathways such as "cellular response to cytokine stimulus", "regulation of immune system process", "regulation of cell activation", and "regulation of cytokine production". Furthermore, after excluding the potential effect of common factors related to surgery and anesthesia between POD cases and non-POD controls, the enrichment analyses showed significant signals such as "immune response" and "T cell activation", which are same pathways previously identified from an independent non-surgical inpatient cohort. CONCLUSIONS: Our first genome-wide DNAm investigation of POD showed promising signals related to immune response, inflammatory response and other relevant signals considered to be associated with delirium pathophysiology. Our data supports the hypothesis that epigenetics play an important role in the pathophysiological mechanism of delirium and suggest the potential usefulness of an epigenetics-based biomarker of POD.

The potential benefit of metformin to reduce delirium risk and mortality: a retrospective cohort study.

PURPOSE: Metformin has been reported to improve age-related disorders, including dementia, and to lower mortality. This study was conducted to investigate whether metformin use lower delirium risk, as well as long-term mortality. METHODS: In this retrospective cohort study, previously recruited 1,404 subjects were analyzed. The relationship between metformin use and delirium, and the relationship between metformin use and 3-year mortality were investigated. MAIN FINDINGS: 242 subjects were categorized into a type 2 diabetes mellitus (DM)-without-metformin group, and 264 subjects were categorized into a DM-with-metformin group. Prevalence of delirium was 36.0% in the DM-without-metformin group, and 29.2% in the DM-with-metformin group. A history of metformin use reduced the risk of delirium in patients with DM (OR, 0.50 [95% CI, 0.32 to 0.79]) after controlling for confounding factors. The 3-year mortality in the DM-without-metformin group (survival rate, 0.595 [95% CI, 0.512 to 0.669]) was higher than in the DM-with-metformin group (survival rate, 0.695 [95% CI, 0.604 to 0.770]) (p=0.035). A history of metformin use decreased the risk of 3-year mortality after adjustment for confounding factors (HR, 0.69 [95% CI, 0.48 to 0.98]). CONCLUSIONS: Metformin use may lower the risk of delirium and mortality in DM patients.

Mortality among patients with sepsis associated with a bispectral electroencephalography (BSEEG) score.

We have previously developed a bispectral electroencephalography (BSEEG) device, which was shown to be effective in detecting delirium and predicting patient outcomes. In this study we aimed to apply the BSEEG approach for a sepsis. This was a retrospective cohort study conducted at a single center. Sepsis-positive cases were identified based on retrospective chart review. EEG raw data and calculated BSEEG scores were obtained in the previous studies. The relationship between BSEEG scores and sepsis was analyzed, as well as the relationship among sepsis, BSEEG score, and mortality. Data were analyzed from 628 patients. The BSEEG score from the first encounter (1st BSEEG) showed a significant difference between patients with and without sepsis (p = 0.0062), although AUC was very small indicating that it is not suitable for detection purpose. Sepsis patients with high BSEEG scores showed the highest mortality, and non-sepsis patients with low BSEEG scores showed the lowest mortality. Mortality of non-sepsis patients with high BSEEG scores was as bad as that of sepsis patients with low BSEEG scores. Even adjusting for age, gender, comorbidity, and sepsis status, BSEEG remained a significant predictor of mortality (p = 0.008). These data are demonstrating its usefulness as a potential tool for identification of patients at high risk and management of sepsis.

Stability of amoxicillin in portable pumps is drug concentration dependent.

Continuous amoxicillin infusion for deep infection's intravenous treatment is performed using elastomeric portable pumps carried under clothing and requires high doses of antibiotic. Therefore, we evaluated the stability of amoxicillin in those medical devices, with particular focus on both drug concentration and storage temperature. Stability of 20, 40, and 60g/L amoxicillin solutions in 300 mL portable pumps stored at 20 or 35 degrees C was studied by visual examination and drug concentration measurements at T0; T0 + 12 h; T0 + 24 h and; T0 + 48 h. Twenty and 40 g/L amoxicillin solutions were stable over 48 h, with a degradation rate that never exceeded 12% at T0 + 24 h, and 18% at T 0 + 48 h. However, the 60 g/L amoxicillin solution degradation rate was significant (p < 0.05, versus C1 and C2) at T0 + 24 h: 24.5 and 26.9% at 20 and 35 degrees C, respectively. This degradation process was amplified at T0 + 48 h, with degradation rates of 37 and 42% at 20 and 35 degrees C, respectively. Stability of amoxicillin in pump is guarantied over 48 h up to concentrations of 40 g/L. At 60 g/L major degradation of the antibiotic was observed.

Rapid induction of polyadenylate binding protein and stimulation of translational initiation in pituitary tumor cells exposed to phorbol ester.

1. GH3 pituitary cells treated for 1-2 hr with phorbol myristate acetate exhibited accumulation of large polysomes and increased incorporation of amino acids into all discrete protein populations. 2. Preferential incorporation into a basic 74 kDa polypeptide preceded significant augmentation of protein synthesis. Cellular content of this polypeptide correlated directly with the increase in protein synthesis. 3. Stimulations of incorporation, of polysome accumulation, and of preferential synthesis of the 74 kDa protein were eliminated by inhibitors of transcription. 4. The rapidly induced protein was identical with the ubiquitous polyadenylate-binding protein on the bases of size, isoelectric point, distribution with polysomes, and association with poly(A) + mRNA.

Evidence of glycosylated sites on the endothelin-1 receptor in Swiss 3T3 cells.

The effects of incubation of intact cells with six different lectins on the specific binding of [125I]endothelin-1 (ET-1) were determined in Swiss 3T3 fibroblasts. ET-1 binding was unaffected by pretreatment of cells for 1 h at 37 degrees C with concanavalin A, soybean agglutinin, Ulex europaeus agglutinin I, peanut agglutinin, or Galanthus nivalis agglutinin. However, preincubation of cells with 300 micrograms/ml of wheat germ agglutinin resulted in a 70% decrease in specific binding of ET-1 to cell-surface receptors. The inhibitory effects of wheat germ agglutinin were diminished by brief incubation of lectin-treated cells with 100 mM N-acetylglucosamine, a monosaccharide specifically recognized by wheat germ agglutinin. Neither glucose nor mannose had any effect on wheat germ agglutinin-mediated inhibition of the specific binding of ET-1. These results suggest that the ET-1 receptor on 3T3 cells is a glycoprotein that contains one or more N-acetylglucosamine residues at or near the ligand binding site.

Smooth muscle cells contain a factor responsible for decreasing big endothelin and endothelin-1 produced by cultured endothelial cells.

The production of big endothelin-1 (big ET-1) and its processing to endothelin (ET-1) were examined in cocultures of bovine pulmonary artery endothelial cells (BPECs) and human bronchiolar smooth muscle cells (HBSMCs). The BPECs produced immunologically reactive ET-1 (ir-ET-1) and big ET-1 (ir-big ET-1) that increased linearly in the cell culture media over a 72 h time course when confluent monolayers were incubated at 37 degrees C in serum-free media. HBSMCs maintained in serum-free media over a 72-h period did not produce any detectable ir-big ET-1 or ir-ET-1. After coculture of these two cell types for 24 h (the monolayers were physically separated), the culture medium contained no detectable ir-big ET-1 or ir-ET-1. When medium conditioned for 24 h with the HBSMCs was transferred to the BPEC monolayers, the accumulation rates of ET-1 and big ET-1 were attenuated 70 and 10%, respectively. When medium conditioned for 24 h with the BPECs was transferred to the HBSM cell monolayers, the amount of ir-ET-1 and ir-big ET-1 in the medium decreased greater than 90% over the next 24 h. Cellular binding and uptake could not account for this decrease as ascertained by quantitation of cellular levels of ET-1 and big ET-1. When conditioned medium from the HBSMCs was added to conditioned medium from the BPECs in a 1:1, 2:1, 3:1, 1:2, or 1:3 ratio (v/v) in the absence of cells, the amount of ET-1 or big ET-1 present in the EC medium did not decrease significantly over the following 24 h. These data imply that HBSMCs contain a factor that is responsible for decreasing the accumulation of ir-big ET-1 and ir-ET-1 in the cell culture media of BPECs. The data also suggest that the most likely mechanism for this effect is a factor that degrades BET-1 and ET-1 at different rates.

Accommodation of protein synthesis to chronic deprivation of intracellular sequestered calcium. A putative role for GRP78.

Mobilization of sequestered intracellular Ca2+ with EGTA or Ca2+ ionophores severely depresses rates of translational initiation in various mammalian cell types including C6 glial, GH3 pituitary and P3X63Ag8 myeloma cells. Within 2-3 h of continuous exposure to either chelator or ionophore, cells adapt or accommodate such that their rates of amino acid incorporation are restored to 40-70% of those of untreated controls. In GH3 and P3X63Ag8 cells, treatment with either a phorbol ester or a cAMP-elevating agent was required to obtain maximal degrees of accommodation of translational initiation. Following the development of accommodation, cells restored with optimal Ca2+ exhibited rates of amino acid incorporation identical with those of nontreated controls but remained resistance to inhibition on subsequent challenge with EGTA or ionophore. Development of translational tolerance to agents depleting Ca2+ stores did not involve alterations in cellular capacity or affinity for the cation. Invariably, the development of tolerance was preceded by transcriptionally dependent, preferential synthesis of the reticuloplasmin GRP78/BiP. In Ca2(+)-deprived GH3 cells, the synthesis of GRP78 was promoted by phorbol ester and cAMP with the extent of induction correlating directly with the degree of translational tolerance to ionophore. Cells pretreated with dithiothreitol, an alternate inducer of GRP78, also became tolerant to translational inhibition by Ca2+ ionophore or EGTA. Amino acid incorporation in nonsecreting NS-1-cloned myeloma cells, which constitutively express high levels of GRP78 and its mRNA, resisted inhibition by EGTA, ionophore, and dithiothreitol. Antisense oligodeoxynucleotides directed against GRP78 mRNA reduced amino acid incorporation in tolerant, but not in non-tolerant, preparations. These results predicate the existence of a mechanism whereby mammalian cells are capable of rapidly developing translational cross-tolerance to either depletion of sequestered Ca2+ or a reducing environment. A role for nascent GRP78 is strongly implicated in this accommodation mechanism.

Lack of biological activity of preproendothelin [110-130] in several endothelin assays.

A 21 amino acid peptide containing the prepropendothelin sequence from amino acids 110 to 130 and two intrachain disulfide bonds was synthesized and tested for biological activity in the following endothelin assays: 1.) a competition binding assay using [125I]ET-1 and dog heart membranes, 2.) three RIA's using 125I-ET-1, -2 and -3 and the respective anti-ET rabbit antisera; and 3.) a contractile activity bioassay using hamster aortic rings. The synthetic peptide which has been referred to as the "endothelin-like" peptide occurs 36 amino acids C-terminal to endothelin in the prepro-protein sequence. It contains only 40% sequence homology to the three endothelin isoforms, but has the same sequence and cyclization pattern of cysteines at positions 1, 3, 11 and 15. Despite the overall similarity in secondary structure to the three isoforms of endothelin and sarafotoxin S6b, preproendothelin [110-130] had no activity in any of the assays when tested at concentrations of 10(-10)M to 10(-5)M.

Inhibition of translational initiation in eukaryotic cells by calcium ionophore.

Ca2+ has been recently reported to be required for high rates of translational initiation in GH3 pituitary cells (Chin, K.-V., Cade, C., Brostrom, C.O., Galuska, E.M., and Brostrom, M.A. (1987) J. Biol. Chem. 262, 16509-16514). In the present investigation low concentrations of the Ca2+ ionophores, A23187 and ionomycin, were found to rapidly suppress the Ca2+-dependent component of protein synthesis in GH3 cells. More ionophore was required to inhibit amino acid incorporation into protein as extracellular Ca2+ was increased. Pre-existing inhibitions of protein synthesis produced by low concentrations of ionophore at low extracellular Ca2+ concentrations were reversed by adjustment to high extracellular Ca2+. Treatment with ionophore reduced the cellular contents of polysomes and 43 S preinitiation complex to values equivalent to those found for Ca2+-depleted cells. Average ribosomal transit times were unaffected by ionophore, and treated cells retained the ability to accumulate polysomes when incubated with cycloheximide. Cell types, such as HeLa and Chinese hamster ovary, that normally display only a modest Ca2+-dependent component of protein synthesis, manifested a strong underlying Ca2+ dependence in amino acid incorporation and polysome formation following treatment with low concentrations of ionophore. Protein synthesis in GH3 or HeLa cells during recovery from heat shock and arsenite treatment was not affected by cellular Ca2+ depletion or ionophore treatment. On the basis of these results, Ca2+ ionophore is proposed to inhibit Ca2+-dependent translational initiation through facilitating the mobilization of sequestered intracellular Ca2+.

Loss of a calcium requirement for protein synthesis in pituitary cells following thermal or chemical stress.

Ca2+ is required for the maintenance of high rates of translational initiation in GH3 pituitary cells (Chin, K.-V., Cade, C., Brostrom, C.O., Galuska, E.M., and Brostrom, M.A. (1987) J. Biol. Chem. 262, 16509-16514). Following thermal stress at 46 degrees C or chemical stress from exposure to sodium arsenite or 8-hydroxyquinoline, rates of amino acid incorporation in Ca2+-restored GH3 cells were reduced acutely to those of unstressed, Ca2+-depleted control preparations. Sodium arsenite treatment resulted in loss of ability to accumulate polysomes in response to Ca2+. Stressed cells allowed to recover for 2-8 h either with or without Ca2+ in the medium exhibited comparable, increasing rates of amino acid incorporation and the induction of heat shock proteins (hsp). Abolition of the Ca2+-dependent component of translation was proportional to the intensity of the stress. Mild thermal stress (41 degrees C) resulted in the induction of hsp 68 and the retention of Ca2+-dependent protein synthesis; hsp 68 was synthesized in a Ca2+-dependent manner. After arsenite stress, restoration of the Ca2+ requirement for protein synthesis occurred by 24 h, and was preceded by a transitional period during which polysomes accumulated in response to Ca2+ without concomitant increased rates of incorporation. Responses to stress are proposed to include an acute inhibition of normal protein synthesis involving the destruction of Ca2+-stimulated initiation and a protracted period of recovery involving synthesis of the hsp accompanied by Ca2+-independent amino acid incorporation and slowed peptide chain elongation.

Regulation of protein synthesis in intact rat liver by calcium mobilizing agents.

1. Exposure of intact perfused rat liver to EGTA, vasopressin or phenylephrine resulted in a rapid decrease in polysome formation. Pretreatment with phentolamine, an alpha-adrenergic antagonist, blocked the effect of phenylephrine. 2. Hormonal inhibitions of leucine incorporation into protein in isolated hepatocytes and of polysome formation in perfused liver were reversed in the presence of supraphysiologic extracellular Ca2+ concentrations. 3. The beta-adrenergic agonist isoproterenol exerted minimal effects on polysome content. 4. It is proposed that intracellular Ca2+ stores sensitive to hormonal modulation are necessary for maintenance of protein synthesis in hepatocytes.

Calcium-dependent regulation of protein synthesis at translational initiation in eukaryotic cells.

Evidence that Ca2+ may serve as a physiologic regulator of post-transcriptional protein synthesis was recently reported (Brostrom, C. O., Bocckino, S. B., Brostrom, M. A., and Galuska, E. M. (1986) Mol. Pharmacol. 29, 104-111). To evaluate further the role of Ca2+ in translation, the polysomal contents of Ca2+-depleted and -restored GH3 pituitary cells were compared. Ca2+ depletion of intact cells with 1 mM EGTA resulted in the disappearance of polysomes and an accumulation of 80 S monosomes and ribosomal subunits typical of slowed rates of initiation. Ca2+ repletion rapidly (minutes) restored cellular polysomal contents with an accompanying accumulation of 43 S preinitiation complex (40 S.eukaryotic initiation factor 2.Met-tRNAf.GTP). Comparable polysomal profiles were found for Ca2+-depleted and -restored cells exposed to cycloheximide which apparently slowed polypeptide chain elongation to rate-limiting values in the overall translation process. Ribosomal transit times for both Ca2+-depleted and -restored cells were identical, indicating that elongation is not directly affected by the cation. Transit times were extended in parallel as a function of increasing cycloheximide concentration. Lysates of GH3 cells exhibited incorporation that was proportional to the polysomal contents derived from the original intact cell preparations. Such lysates did not possess the ability to initiate new peptide synthesis and were not affected by Ca2+ or EGTA. Ca2+-depleted cells exposed to cycloheximide provided lysates with identical elongation activity to that of lysates prepared from either comparably treated or control Ca2+-restored cells. Ca2+ is proposed to regulate translation in intact cells through modulation of the rate of initiation rather than either polypeptide chain elongation or termination.

Stimulation of protein synthesis in pituitary cells by phorbol esters and cyclic AMP. Evidence for rapid induction of a component of translational initiation.

Phorbol esters such as phorbol myristate acetate (PMA) were employed to examine the involvement of protein kinase C in the regulation of protein synthesis in intact GH3 pituitary tumor cells. Amino acid incorporation increased as a function of time of pretreatment with these agents; 4-8- and 2-3-fold stimulations were observed for Ca2+-depleted and -restored preparations, respectively, following 2 h of exposure. PMA enhanced incorporation of amino acid into all detectable polypeptide species. Lysates of PMA-treated cells incorporated amino acid more efficiently than did lysates of untreated controls. Cells slowed at initiation by Ca2+ depletion responded to treatment with PMA with the production of low molecular weight polysomes and a concomitant decrease in 80 S monomers. In Ca2+-restored preparations, which form large polysomes, PMA treatment resulted in a decrease in 80 S monomers and a shift in average polysomal size from smaller to larger molecular weight. Ribosomal transit times, however, were not altered. PMA-stimulated amino acid incorporation and polysome formation were either eliminated or reduced significantly by actinomycin D and could not be ascribed to increased amino acid uptake or methionylation of tRNA. Substances which elevate cAMP in GH3 cells mimicked phorbol ester in its actions on protein synthesis. It is proposed that GH3 cells, in response to various stimuli, rapidly synthesize an mRNA that subsequently increases the synthesis of a rate-limiting component of translational initiation. Evidence that this pathway for translational control may function in alternative cell types is also presented.

Effect of dietary calcium, phosphate and vitamin D deprivation on the pharmacokinetics of 1,25-dihydroxyvitamin D3 in the rat.

The in vivo regulation of circulating 1,25(OH)2D3 concentrations by vitamin D status and by dietary calcium and phosphate deficiency was studied. Adult rats were cannulated in the jugular vein and the clearance of physiological doses of 1,25(OH)2D3 monitored. In vitamin D-replete rats we investigated the effects of dietary calcium and phosphate deficiency on the elimination half life of 1,25(OH)2D3 The results showed no effect of dietary phosphate deficiency on the elimination half life of 1,25(OH)2D3. Dietary calcium deficiency resulted in a small increase of the 1,25(OH)2D3 elimination half life (P = 0.04) (normal diet: 16.3 +/- 1.8 hrs, n = 6; -Ca diet: 18.6 +/- 1.1 hrs, n = 5; -P diet: 16.0 +/- 1.4 hrs, n = 6; mean +/- SD). The experiments with the vitamin D deficient rats showed a marked increase in the elimination half life of 1,25(OH)2D3 (36.4 +/- 6.8 hrs, n = 7), when compared to the rats on the normal diet (P = 0.001). From the experiments in the vitamin D replete rats one can infer that regulation of circulating 1,25(OH)2D3 concentrations by dietary calcium or phosphate takes place at the production site and not by changes in elimination rate. However, vitamin D status appears to regulate circulating 1,25(OH)2D3 concentrations also through an effect on the elimination rate.

Parathyroid hormone stimulation of mitosis in rat thymic lymphocytes is independent of cyclic AMP.

The in vitro mitotic response of rat thymic lymphocytes to hPTH(1-34), hPTH (1-38), and 8,18 Nle hPTH(1-34) exhibits a dependency upon extracellular calcium. Removal of extracellular calcium or the addition of Verapamil (5 micrograms/ml) or trifluoroperazine (10 microM) abrogated the mitotic response. Mitogenic concentrations of 8,18 Nle hPTH(1-34) increased calcium 45 uptake from 4.49 +/- 0.25 to 8.23 +/- 0.75 pMol/10(6) cells/min. The intracellular calcium concentration, measured by Quin 2 fluorescence, also increased after addition of 8,18 Nle hPTH(1-34). Parathyroid hormone-induced activation could not be demonstrated in an otherwise responsive thymocyte membrane adenylate cyclase. In intact cells mitogenic levels of 8,18 Nle hPTH(1-34) decreased intracellular cyclic AMP content. This response was blocked by both 3-isobutyl 1-methyl xanthine and trifluoroperazine, and may indicate activation of calcium-dependent phosphodiesterase. We conclude that PTH stimulates thymic lymphocyte proliferation independently of cyclic AMP, and that changes in cellular calcium homeostasis are intimately involved in the action of PTH. In all of the assays employed, the hitherto antagonistic analogue 8,18 Nle 34 Tyr bPTH(3-34)amide proved to be an agonist. We postulate that the receptor utilized for this PTH action may not exhibit classical PTH structure-activity specificities.