The effect of DL-propranolol on γ-aminolevulinic acid synthetase activity and urinary excretion of porphyrins in allylisopropylacetamide-induced experimental porphyria

Experimental porphyria was induced in rats by allylisopropylacetamide. DL-Propranolol, a β-adrenergic-receptor blocking agent, significantly reduced the elevated urinary excretion of δ-aminolevulinic acid, porphobilinogen and total porphyrins. DL-Propranolol also partially prevented the increased activity of δ-aminolevulinic acid synthesis in liver homogenates of allylisopropylacetamide-treated rats. It had no effect on the above parameters in normal rats. These findings support the hypothesis that δ-aminolevulinic acid exists in two forms, a constitutive and an inducible one.In order to examine whether the action of the drug was caused by its membrane effect. D-propranolol and quinidine sulphate were used in similar sets of experiments. These drugs had no effect on the abnormal porphyrin metabolism of allylisoprpyl-acetamide-treated rats, indicating that the results obtained with DL-propranolol were not due to its membrane action.     

Rb+ influxes differentiate between growth arrest of cells by different agents

The effect of cell cycle on Rb+ (K+) fluxes was studied in NIH 3T3 mouse fibroblasts. Serum starvation or isoleucine deprivation resulted in cell arrest at an early G1/G0 phase, accompanied by a marked decrease in both ouabain-sensitive and ouabain-resistant Rb+ influx. On the other hand, cells arrested at late G1/G0 phase by hydroxyurea treatment have high ouabain-sensitive and ouabain-resistant Rb+ influx. Butyric acid treatment resulted in cell arrest at an early G1/G0 phase, but in contrast to serum or isoleucine starvation did not decrease Rb+ influxes. It is thus shown that quiescent cells may have Rb+ influx rates as high as that of logarithmically growing cells. The results are consistent with the hypothesis that an increased ion permeability of the cell is initiated at a critical stage in G1/G0 phase, and that butyric acid may arrest the cell beyond that stage.     

Differentiation between serum stimulation of ouabain-resistant and sensitive Rb influx in quiescent NIH 3T3 cells

Summary The addition of serum to quiescent NIH 3T3 mouse cell cultures resulted in a 10- to 20-fold increase of Rb influx which was resistant to ouabain, and only a three- to fourfold activation of ouabain-sensitive Rb influx. Stimulation of the ouabain-resistant Rb influx following serum addition reached its maximum within 2 min. The stimulation of ouabain-resistant Rb influx was a result ofV _m increase while theK _m for Rb was unchanged. Ouabain-resistant Rb influx, after serum addition, was resistant to amiloride and sensitive to ethacrinic acid. Replacing chloride in the medium by NO₃ ^–, CO₃ ^– and CH₃COO^– resulted in a drastic decrease in the ouabain-resistant Rb influx. It appeared, therefore, that the ouabain-resistant Rb influx in NIH 3T3 cells was Cl^–-dependent.     

Target cells for the activity of a synthetic adjuvant: muramyl dipeptide.

Muramyl dipeptide (MDP), a synthetic adjuvant, increased the primary response of CBA mice to sheep red blood cells (SRBC). In reconstituted irradiated recipients, cooperation between T and B lymphocytes was required for the expression of adjuvant activity and MDP increased the efficiency of SRBC-educated T cells. The role of T-derived lymphocytes in mediating the MDP adjuvant activity was also demonstrated in irradiated mice and in mice reconstituted with various splenic cellular types of donors which had received SRBC and MDP 24 hr earlier. In our experiments, the macrophage did not seem to be involved, since MDP did not increase the phagocytic capacity of peritoneal exudate cells and MDP- and SRBC-pretreated macrophages had no increased ability to induce an anti-SRBC immune response. These results demonstrate the importance of T lymphocytes as mediators of the adjuvant activity of MDP.     

Direct interaction of endogenous Kv channels with syntaxin enhances exocytosis by neuroendocrine cells

K(+) efflux through voltage-gated K(+) (Kv) channels can attenuate the release of neurotransmitters, neuropeptides and hormones by hyperpolarizing the membrane potential and attenuating Ca(2+) influx. Notably, direct interaction between Kv2.1 channels overexpressed in PC12 cells and syntaxin has recently been shown to facilitate dense core vesicle (DCV)-mediated release. Here, we focus on endogenous Kv2.1 channels and show that disruption of their interaction with native syntaxin after ATP-dependent priming of the vesicles by Kv2.1 syntaxin-binding peptides inhibits Ca(2+) -triggered exocytosis of DCVs from cracked PC12 cells in a specific and dose-dependent manner. The inhibition cannot simply be explained by the impairment of the interaction of syntaxin with its SNARE cognates. Thus, direct association between endogenous Kv2.1 and syntaxin enhances exocytosis and in combination with the Kv2.1 inhibitory effect to hyperpolarize the membrane potential, could contribute to the known activity dependence of DCV release in neuroendocrine cells and in dendrites where Kv2.1 commonly expresses and influences release.     

CD24 and APC Genetic Polymorphisms in Pancreatic Cancers as Potential Biomarkers for Clinical Outcome

Background

There are no validated biomarkers that correlate with the prognosis of pancreatic ductal adenocarcinoma (PDA). The CD24 and adenomatous polyposis coli (APC) genes are important in the malignant transformation of gastrointestinal cells. This study examined APC and CD24 genetic polymorphisms and their possible impact on survival of patients with PDA.

Methods

Clinical and pathological data as well as blood samples for extracting DNA were obtained for 73 patients with PDA. Real-time PCR assessed genetic variants of APC (I1307K and E1317Q), and four different single nucleotide polymorphisms (SNPs) in the CD24 gene: C170T (rs52812045), TG1527del (rs3838646), A1626G (rs1058881) and A1056G (rs1058818).

Results

The median age at diagnosis was 64 (41–90) years. Thirty-one patients (42.5%) were operable, 16 (22%) had locally advanced disease and 26 (35.5%) had disseminated metastatic cancer. The malignancy-related mortality rate was 84%. Median survival was 14 months (11.25–16.74). Survival was similar for wild-type (WT), heterozygous and homozygous variants of the APC or CD24 genes. The three most frequent CD24 SNP combinations were: heterozygote for A1626G and WT for the rest of the alleles (14% of patients), heterozygote for C170T, A1626G, A1056G and WT for the rest (14% of patients), and heterozygote for C170T, A1056G and WT for the rest (10% of patients). All patients were APC WT. The first two groups were significantly younger at diagnosis than the third group.

Conclusions

Specific polymorphisms in the APC and CD24 genes may play a role in pancreatic cancer development. Correlation with survival requires a larger cohort.     

PSMA PET/CT to evaluate response to SBRT for prostate cancer bone metastases

BackgroundIn the current study we evaluated ⁶⁸Ga PSMA PET/ CT to measure local control of bone metastasis in oligometastatic prostate cancer patients treated with SBRT.Materials and methodsAfter the institutional review board approval, a retrospective review of medical records of consecutive prostate cancer patients treated between 2014 and 2018 was conducted. Only medical records of patients that were treated with SBRT for bone metastasis and had pre-and post-SBRT ⁶⁸Ga PSMA PET/CT scans were included in our study. Data extracted from the medical files included patient-related (age), disease-related (Gleason score, site of metastasis), and treatment-related factors and outcomes.ResultsDuring the study period, a total of 12 patients (15 lesions) were included, with a median age of 73 years. The median follow-up was 26.5 months (range 13–45 months). Median time of ⁶⁸Ga PSMA PET/ CT follow up was 17.0 months (range 3–39 months). The median pre-treatment PSA was 2 ng/mL (range 0.56–44 ng/mL) vs. post treatment PSA nadir of 0.01 ng/mL (0.01–4.32) with a median time to nadir of 7 months (range, 2–12). Local control was 93% during the follow up period and there was correlation with PS MA avidity on PE T. None patients developed recurrences in the treated bone. None of the patients had grade 3 or more toxicities during follow-up.ConclusionsSBRT is a highly effective and safe method for treatment of prostate cancer bone metastases. More studies are required to determine if SBRT provides greater clinical benefit than standard fractionation for oligometastatic prostate cancer patients. ⁶⁸Ga PSMA PET/CT should be further investigated for delineation and follow-up.