A novel enemy of cancer: recent investigations into protozoan anti-tumor properties

Cancer remains a significant global health issue, despite advances in screening and treatment. While existing tumor treatment protocols such as surgery, chemotherapy, radiotherapy, targeted therapy, and immunotherapy have proven effective in enhancing the prognosis for some patients, these treatments do not benefit all patients. Consequently, certain types of cancer continue to exhibit a relatively low 5-year survival rate. Therefore, the pursuit of novel tumor intervention strategies may help improve the current effectiveness of tumor treatment. Over the past few decades, numerous species of protozoa and their components have exhibited anti-tumor potential via immune and non-immune mechanisms. This discovery introduces a new research direction for the development of new and effective cancer treatments. Through in vitro experiments and studies involving tumor-bearing mice, the anti-tumor ability of Toxoplasma gondii, Plasmodium, Trypanosoma cruzi, and other protozoa have unveiled diverse mechanisms by which protozoa combat cancer, demonstrating encouraging prospects for their application. In this review, we summarize the anti-tumor ability and anti-tumor mechanisms of various protozoa and explore the potential for their clinical development and application.

Construction of PEI-EGFR-PD-L1-siRNA dual functional nano-vaccine and therapeutic efficacy evaluation for lung cancer

BACKGROUND

PD-1/PD-L1 tumor immunotherapy shows effective anticancer in treatment of solid tumors, so PEI lipid nanoparticles (PEI-LNP)/siRNA complex (EPV-PEI-LNP-SiRNA) with the therapeutic function of PD-L1-siRNA and EGFR short peptide/PD-L1 double immune-enhancing function were constructed for the prevention and treatment of EGFR-positive lung cancer in this study.

METHOD

In this study, PEI lipid nanoparticles (PEI-LNP)/siRNA complex (EPV-PEI-LNP-siRNA) with the therapeutic function of PD-L1-siRNA and EGFR short peptide/PD-L1 double immune-enhancing function were constructed for the prevention and treatment of EGFR-positive lung cancer and functional evaluation was conducted.

RESULTS

On the basis of the construction of the composite nano-drug delivery system, the binding capacity, cytotoxicity, apoptosis and uptake capacity of siRNA and EPV-PEI-LNP were tested in vitro, and the downregulation effect of PD-L1 on A549 cancer cells and the cytokine levels of cocultured T cells were tested. Lipid nanoparticles delivered siRNA and EGFR short peptide vaccine to non-small cell lung cancer (NSCLC), increasing tumor invasion and activation of CD8 + T cells. Combination therapy is superior to single target therapy.

CONCLUSION

Our constructed lipid nanoparticles of tumor targeted therapy gene siRNA combination had the ability to target cells in vitro and downregulate the expression of PD-L1, realizing the tumor-specific expression of immune-stimulating cytokines, which is a highly efficient and safe targeted therapy nano-vaccine.

Significance of Parkinson Family Genes in the Prognosis and Treatment Outcome Prediction for Lung Adenocarcinoma

Epidemiological investigations have shown that patients with Parkinson's disease (PD) have a lower probability of developing lung cancer. Subsequent research revealed that PD and lung cancer share specific genetic alterations. Therefore, the utilisation of PD biomarkers and therapeutic targets may improve lung adenocarcinoma (LUAD) diagnosis and treatment. We aimed to identify a gene-based signature from 25 Parkinson family genes for LUAD prognosis and treatment choice. We analysed Parkinson family gene expression and protein levels in LUAD, utilising multiple databases. Least absolute shrinkage and selection operator (LASSO) regression was used to construct a prognostic model based on the TCGA-LUAD cohort. We validated the model in external GEO cohorts. Immune cell infiltration was compared between risk groups, and GEO data was used to explore the model's predictive ability for LUAD treatment response. Nearly all Parkinson family genes exhibited significant differential expression between LUAD and normal tissues. LASSO regression confirmed that our seven Parkinson family gene-based signature had excellent prognostic performance for LUAD, as validated in three GEO cohorts. The high-risk group was clearly associated with low tumour immune cell infiltration, suggesting that immunotherapy may not be an optimal treatment choice. This is the first Parkinson family gene-based model for the prediction of LUAD prognosis and treatment outcome. The association of these genes with poor prognosis and low immune infiltration requires further investigation.

[Functional lateralization of major Chinese language cortex for presurgical evaluation in neurosurgery]

Objective: To investigate the functional lateralization of major Chinese language cortex in patients with cerebral arteriovenous malformation (AVM) in dominant hemispheric via functional magnetic resonance imaging (fMRI). Methods: Nine right-handed normal volunteers and fourteen patients with cerebral AVM in dominant hemisphere diagnosed in Beijing Tiantan Hospital between December 2017 and June 2018 were included. Three language tasks (semantic judgment, word reading, and listening comprehension) were applied to activate language areas. Lateralization index (LI) was used to show the dominant hemisphere. Results: In the control group, right-sided lateralization of BOLD signal activations was observed in 0/27 (0%) of the language tasks. While in the AVM patients, right-sided lateralization of BOLD signal activations was observed in 8/42 (19%) language tasks. The difference was statistically significant (χ(2)=5.73, P=0.019). Conclusions: The dominant hemisphere of different language tasks may be different in patients with cerebral lesions. Compared with normal controls, patients with cerebral AVM in dominant hemispheric are more likely to have right-sided lateralization of language cortex.

Attenuated plasmodium sporozoite expressing MAGE-A3 induces antigen-specific CD8+ T cell response against lung cancer in mice

Objective

Cancer vaccines that rely on tumor antigen-specific CD8⁺ T cell responses, are promising anti-cancer adjuvant immunotherapies. This study investigated whether genetically attenuated Plasmodium sporozoite (GAS) could be used as a novel vector to induce antigen-specific CD8⁺ T cell responses against lung cancer.

Methods

We constructed GAS/MAGE-A3, a recombinant GAS engineered to express the lung cancer-specific antigen, melanoma-associated antigen 3 (MAGE-A3), and assessed its therapeutic effects against lung cancer.

Results

Robust parasite-specific CD8α^lowCD11a^high and CD49d^highCD11a^high CD4⁺ T cell responses as well as a MAGE-A3-specific CD8⁺ T cell response were induced in GAS/MAGE-A3-immunized mice. Adoptive transfer of GAS/MAGE-A3-induced CD8⁺ T cells from HLA-A2 transgenic mice into lung cancer-bearing nude mice inhibited tumor growth and prolonged survival.

Conclusions

These findings demonstrate that GAS/MAGE-A3 induces a strong MAGE-A3-specific CD8⁺ T cell response against lung cancer in vivo, and indicate that GAS is a novel and efficacious antigen delivery vector for antitumor immunotherapy.

Comparison of clinical outcomes after thoracoscopic sublobectomy versus lobectomy for Stage I nonsmall cell lung cancer: A meta-analysis

BACKGROUND

Although lobectomy has long been considered the standard procedure for Stage I nonsmall cell lung cancer (NSCLC), the selection of sublobectomy for Stage I NSCLC remains controversial. Amidst growing enthusiasm for minimally invasive surgery, the comparison of clinical outcomes after thoracoscopic sublobectomy versus thoracoscopic lobectomy may be of immense value.

OBJECTIVE

The present study aimed to compare the overall survival (OS) and disease-free survival (DFS) outcomes of patients who underwent thoracoscopic sublobectomy with those who underwent thoracoscopic lobectomy for Stage I NSCLC.

METHODS

An electronic search was conducted using five online databases from their dates of inception to February 2014. Hazard ratio (HR) was used in this meta-analysis, calculated from the published survival data.

RESULTS

Eight studies met the selection criteria, including a total of 1613 patients (463 patients underwent thoracoscopic sublobectomy, and 1150 patients underwent thoracoscopic lobectomy). From the available data, compared with thoracoscopic sublobectomy, there was a significant benefit of thoracoscopic lobectomy on OS (HR: 1.45; 95% confidence interval [CI]: 1.11-1.90; P = 0.007). However, in subgroup analysis of thoracoscopic segmentectomy and thoracoscopic lobectomy, there was no significant difference in OS (HR: 1.03; 95% CI: 0.76-1.39; P = 0.85) or DFS (HR: 1.19; 95% CI: 0.67-2.10; P = 0.56) between the two groups. In addition, compared with thoracoscopic wedge resection, there was a significant benefit of thoracoscopic lobectomy on OS (HR: 4.19; 95% CI: 2.19-8.03, P < 0.0001).

CONCLUSION

For Stage I patients, thoracoscopic segmentectomy leads to survival rates comparable to thoracoscopic lobectomy. However, the overall several of thoracoscopic lobectomy is superior to that of wedge resection.

Association of IL-18 polymorphisms with rheumatoid arthritis: a meta-analysis

Interleukin-18 (IL-18), an important proinflammatory cytokine, has been reported to play a potential pathological role in rheumatoid arthritis (RA). Results from previous studies on the association between IL-18 polymorphisms and RA are conflicting. To clarify this, an updated meta-analysis of all available studies on IL-18 polymorphisms and RA was conducted. Eligible articles were identified by searching databases, including PubMed, Ovid, Cochrane Library, EMBASE, and China Knowledge Resource Integrated Database, for the period up to May 1, 2015. The pooled odds ratios (ORs) with 95% confidence intervals (95%CIs) were used to assess the strength of association in the homozygote, heterozygote, dominant, recessive, and additive models. The software STATA (Version 13.0) was used for statistical analysis. Finally, 14 articles were included in the present meta-analysis. The IL-18 -607C/A polymorphism showed pooled ORs and 95%CIs for the homozygote model (AA vs CC: OR = 0.598; 95%CI = 0.395-0.907), and the association between the IL-18 -137G/C polymorphism and RA showed pooled ORs and 95%CIs for the homozygote (CC vs GG: OR = 0.699; 95%CI = 0.364-1.342) and heterozygote (CG vs GG: OR = 0.924; 95%CI = 0.803-1.064) models. In summary, the current meta-analysis, which was based on the most current studies, showed that the -607A/C, -920C/T, and -105A/C polymorphisms in IL-18 were significantly associated with increased RA risk. However, the -137C/G polymorphism was not associated with RA risk under any genetic model. More evidence is needed to support or deny such a conclusion.

Somatostatin receptors SSTR2 and SSTR5 are expressed in the human thoracic duct

Somatostatin and its analog octreotide have been used successfully to treat postoperative chylothorax, and it has been shown that octreotide binds with high affinity to somatostatin receptor (SSTR) subtypes 2 and 5. Therefore, we investigated expression of SSTR2 and SSTR5 in the human thoracic duct by immunohistochemistry. Normal rat pancreas was used as a positive control for antibodies against SSTR2 and SSTR5, and Factor VIII-related antigen, SMA, actin, elastin, or collagen type II, III, IV or V antibodies were used to identify cell types and structures within the human thoracic duct. The antibodies against SSTR2 and SSTR5 worked well and yielded positive staining in control rat islets. In the human thoracic duct, SSTR2 was present in smooth muscle cells and some scattered structures which were stained by antibodies against Factor VIII-related antigen, SMA, actin, elastin or collagen type II, III, IV or V. SSTR5 was also present in smooth muscle cells. The presence of SSTR2 and SSTR5 in the human thoracic duct sheds light on the mechanism of somatostatin and octreotide use in the successful treatment of chylothorax and offers new molecular pathways to explore for potential future therapies.

Autonomous and growth factor-induced hypertrophy in cultured neonatal mouse cardiac myocytes. Comparison with rat

Cultured neonatal rat cardiac myocytes have been used extensively to study cellular and molecular mechanisms of cardiac hypertrophy. However, there are only a few studies in cultured mouse myocytes despite the increasing use of genetically engineered mouse models of cardiac hypertrophy. Therefore, we characterized hypertrophic responses in low-density, serum-free cultures of neonatal mouse cardiac myocytes and compared them with rat myocytes. In mouse myocyte cultures, triiodothyronine (T3), norepinephrine (NE) through a beta-adrenergic receptor, and leukemia inhibitory factor induced hypertrophy by a 20% to 30% increase in [(3)H]phenylalanine-labeled protein content. T3 and NE also increased alpha-myosin heavy chain (MyHC) mRNA and reduced beta-MyHC. In contrast, hypertrophic stimuli in rat myocytes, including alpha(1)-adrenergic agonists, endothelin-1, prostaglandin F(2alpha), interleukin 1beta, and phorbol 12-myristate 13-acetate (PMA), had no effect on mouse myocyte protein content. In further contrast with the rat, none of these agents increased atrial natriuretic factor or beta-MyHC mRNAs. Acute PMA signaling was intact by extracellular signal-regulated kinase (ERK1/2) and immediate-early gene (fos/jun) activation. Remarkably, mouse but not rat myocytes had hypertrophy in the absence of added growth factors, with increases in cell area, protein content, and the mRNAs for atrial natriuretic factor and beta-MyHC. We conclude that mouse myocytes have a unique autonomous hypertrophy. On this background, T3, NE, and leukemia inhibitory factor activate hypertrophy with different mRNA phenotypes, but certain Gq- and protein kinase C-coupled agonists do not.

Cardiovascular alpha1-adrenoceptor subtypes: functions and signaling

alpha-Adrenoceptors (alpha1AR) are G protein-coupled receptors and include alpha1A, alpha1B, and alpha1D subtypes corresponding to cloned alpha1a, alpha1b, and alpha1d, respectively. alpha1AR mediate several cardiovascular actions of sympathomimetic amines such as vasoconstriction and cardiac inotropy, hypertrophy, metabolism, and remodeling. alpha1AR subtypes are products of separate genes and differ in structure, G protein-coupling, tissue distribution, signaling, regulation, and functions. Both alpha(1A)AR and alpha(1B)AR mediate positive inotropic responses. On the other hand, cardiac hypertrophy is primarily mediated by alpha(1A)AR. The only demonstrated major function of alpha(1D)AR is vasoconstriction. alpha1AR are coupled to phospholipase C, phospholipase D, and phospholipase A2; they increase intracellular Ca2+ and myofibrillar sensitivity to Ca2+ and cause translocation of specific phosphokinase C isoforms to the particulate fraction. Cardiac hypertrophic responses to alpha1AR agonists might involve activation of phosphokinase C and mitogen-activated protein kinase via Gq x alpha1AR subtypes might interact with each other and with other receptors and signaling mechanisms.

Distribution of alpha1-adrenoceptor subtype proteins in different tissues of neonatal and adult rats

Distribution of alpha(1)-adrenoceptor (alpha(1)AR) subtype (alpha(1A), alpha(1B), alpha(1D)) proteins in brain, heart, kidney, and liver of 1-week-old rats and in brain, heart, aorta, kidney, liver, vas deferens, prostate, and adrenal glands of adult rats was investigated by Western analysis, using receptor subtype specific polyclonal antibodies. High levels of immunoreactive alpha(1A)AR and alpha(1D)AR in brain and heart and of alpha(1B)AR in liver and heart of neonatal rats were detected. In adult rat tissues, the abundance of alpha(1A)AR protein was most marked in the brain, intermediate in heart, aorta, liver, vas deferens, and adrenals, and minimal in the kidney and prostate; relative to other tissues, the expression of alpha(1B)AR was higher in brain and heart and that of alpha(1D)AR in brain. All the three receptor subtypes increased with age in the brain cortex, whereas the abundance of alpha(1B)AR increased in the heart but decreased in the liver; alpha(1A)AR and alpha(1D)AR in liver, kidney, and heart were not affected by age. It is concluded that alpha(1)AR subtypes are widely expressed in different neonatal and adult rat tissues.

Inverse agonist activities of beta-adrenoceptor antagonists in rat myocardium

1. Negative inotropic effects of several beta-adrenoceptor (betaAR) antagonists on electrically-stimulated right atria, left atria, right ventricles and left ventricular papillary muscles from reserpine-treated rats were used as a measure of their inverse agonist activities. 2. Beta1AR antagonists acebutolol, atenolol and metoprolol, beta2AR antagonist ICI-181,551 and nonselective betaAR antagonists alprenolol, nadolol, propranolol and timolol produced negative inotropic effects, which were most marked on the right atria. 3. The nonselective betaAR antagonist pindolol did not exhibit inverse agonist activity but inhibited the negative inotropic activities of ICI-118,551, atenolol and propranolol. 4. The negative inotropic effects of lidocaine, nifedipine and pentobarbitone were similar on all the four myocardial preparations. 5. The positive inotropic efficacy of salbutamol on right and left atria but not on right ventricles and papillary muscles was comparable to that of isoprenaline. The antagonist activity of ICI-118,551 against isoprenaline was greater on right atria than on other cardiac regions. 6. Beta1AR proteins were expressed in all regions of the heart but of beta2AR were primarily localized in the right atrium. 7. It is concluded that beta2AR play a greater role in right atria than in other cardiac regions and almost all betaAR antagonists behave as inverse agonists.

Crosstalk between alpha-1A and alpha-1B adrenoceptors in neonatal rat myocardium: implications in cardiac hypertrophy

The myocardial effect of alpha-1A adrenoceptor (alpha-1 AR) agonists in neonatal rats are mediated by alpha-1A AR and not by alpha-1B AR, although both receptor subtypes are equally expressed; the functions of alpha-1B AR are not known. Here, we report that alpha-1 B ARs inhibit the activities of alpha-1A ARs in neonatal rat myocardium so that the inactivation of alpha-1 B ARs by chloroethylclonidine (CEC) potentiated the effects of nonselective alpha-1 AR agonist phenylephrine (PE) on myocardial protein synthesis and early gene (c-fos and c-jun) expression. CEC did not modify the hypertrophic effect of angiotensin II. The potentiation of the effects of PE by CEC was associated with a translocation of Ca(++)-dependent protein kinase C (PKC)alpha, which did not occur in the absence of CEC. Alpha-1A AR-selective agonist A61603 was approximately 1000-fold more potent than PE as a positive inotropic agent; it caused the translocation of PKC alpha, which was not affected by CEC. 5-Methylurapidil antagonized the effects of PE and A61603, suggesting that these were mediated via alpha-1A ARs. Alpha-1D AR antagonist BMY 7378 did not modify PE-induced translocation of PKC. CEC potentiated the effects of PE on Ca++ transients in Fura 2-AM-loaded dispersed cardiomyocytes, and this potentiation was prevented by nifedipine. In whole-cell patch-clamp recordings of cultured cardiomyocytes, CEC potentiated the effect of norepinephrine on Ca++ channel currents, which was blocked by 5-methylurapidil. We conclude that alpha-1A ARs are positively and alpha-1B ARs are negatively coupled to nifedipine-sensitive Ca++ channels, possibly via Gi protein, and this antagonistic relationship between alpha-A AR and alpha-1B AR in the neonatal heart might be required physiologically for normal alpha-1 AR-mediated responses and myocardial development.

Differential effects of rat pregnancy on uterine and lung atrial natriuretic factor receptors

We investigated if the refractoriness to the tocolytic effects of atrial natriuretic factor (ANF) during rat pregnancy is due to a downregulation of one or both guanylyl cyclase (GC)-coupled GC-A and GC-B ANF receptors; lungs were used as controls. Uteri and lungs of virgin, pregnant (days 7, 16, and 21), and day 2 postpartum rats expressed mRNAs for GC-A and GC-B as well as GC-uncoupled ANF-C receptors. GC-B receptor protein was more abundant than GC-A in uteri; the reverse was the case in lungs. Pregnancy decreased uterine mRNAs and proteins for GC-A and GC-B receptors as well as the effects of ANF and C-type natriuretic peptide (CNP) on uterine GC activity; lung ANF receptors and effects of ANF and CNP on lung GC activity were not modulated by pregnancy. It is concluded that pregnancy induces organ-specific modulation of ANF receptors and a downregulation of ANF-GC receptors would minimize interference with uterine motility during pregnancy.

Role of Ca(2+)-independent PKC in alpha 1-adrenoceptor-mediated inotropic responses of neonatal rat hearts

We investigated the role of protein kinase C (PKC) in alpha 1-adrenoceptor (alpha 1-AR)-mediated positive inotropic responses of neonatal rat myocardium. Bisindolylmaleimide (BIM), an inhibitor of all PKC isoforms, reduced the positive inotropic responses to phenylephrine and methoxamine but not to isoproterenol. The positive inotropic effect of phenylephrine was not attenuated by Gö-6976, a selective inhibitor of Ca(2+)-dependent isoforms; it was potentiated by the 1,2-diacylglycerol kinase inhibitor R-59949. Phorbol 12,13-dibutyrate, an activator of both Ca(2+)-dependent and-independent PKC isoforms, as well as thymeleatoxin, a selective activator of Ca(2+)-dependent PKC isoforms, inhibited myocardial contractions, which were prevented by BIM and Gö-6976. BIM inhibited the phenylephrine-induced increase in particulate PKC activity but not the increase in phosphatidylinositide turnover. Phenylephrine induced translocation of only Ca(2+)-independent PKC-epsilon and -delta. These results suggest that activation of Ca(2+)-independent PKC isoforms by alpha 1-AR agonists plays a key role in alpha 1-AR-mediated positive inotropic effect on neonatal myocardium.

Mechanisms of the atrium-specific positive inotropic activities of quinidine- and atropine-like agents in rats

This study investigated the mechanism of the positive inotropic effects of class 1 antiarrhythmic agents using electrically stimulated right atria (sinoatrial node excised), left atria and right ventricles of rats. Quinidine, disopyramide and procainamide produced concentration-dependent positive inotropic effects on right and left atria; effects on the right atria were greater than on left atria. At concentration producing positive inotropic effects on atria, the contractions of right ventricles were slightly increased by quinidine, unaffected by disopyramide and decreased by procainamide. The positive inotropic effects of quinidine were inhibited by propranolol, reserpine and mecamylamine but not by cocaine, hexamethonium and d-tubocurarine; propranolol also antagonized the positive inotropic effects of disopyramide and procainamide. Bupivacaine, which like quinidine blocks transient outward potassium current, slightly increased the contractions of right atria but not of left atria and ventricles. The atrium-specific positive inotropic effects of quinidine were mimicked by atropine, pirenzepine and dimethylphenylpiperazinium but not by nicotine, cytisine and butyrylcholine; the effects of atropine, dimethylphenylpiperazinium and pirenzepine were also blocked by propranolol. Quinidine increased the release of norepinephrine from atria but not from the ventricles; this release was greater from the right than from the left atria. It is concluded that quinidine- and atropine-like agents exert atrium-specific positive inotropic effects by blocking muscarinic receptors and permitting a dominance of acetylcholine effects via a release of norepinephrine from sympathetic nerve terminals.

Alpha 1D-adrenoceptors do not contribute to inotropic responses of neonatal rat myocardium

This study investigated the role of alpha 1D-adrenoceptors (ARs) in the inotropic responses of neonatal (7-day-old) rat myocardium by using the relatively selective antagonist BMY 7378. The positive inotropic effects of phenylephrine on right ventricular strips of neonatal rats were not inhibited by BMY 7378 up to a concentration of 300 nM but potently antagonized by the alpha 1AAR antagonist 5-methylurapidil (5-MU) (pKB, 8.73 +/- 0.12; n = 6). BMY 7378 was approximately 1,000-fold less potent (pKi, 6.63 +/- 0.7; n = 5) in inhibiting the binding of [3H]prazosin to right ventricular membrane preparations of neonatal rats than was 5-MU (pKi, 9.04 +/- 0.54; n = 5). Neonatal rat cerebral cortex and adult rat aorta were used as additional controls. BMY 7378 was a weak inhibitor of [3H]prazosin binding to neonatal cortex (pKi, 6.8 +/- 0.04; n = 3) but highly potent in inhibiting the binding to adult rat aortic membrane preparations (pKi for high-affinity binding, 9.70 +/- 0.30; n = 4); BMY 7378 potently antagonized the effects of phenyleprine on adult rat aortic strips (pKB, 9.05 +/- 0.11; n = 5). It is concluded that alpha 1DARs do not play a significant role in alpha 1AR-mediated inotropic responses of neonatal rat myocardium.

Characterization of alpha 1 D-adrenoceptor subtype in rat myocardium, aorta and other tissues

1. This study was done to characterize the functional role of alpha 1D-adrenoceptors in rat myocardium, aorta, spleen, vas deferens and prostate by use of the selective antagonist BMY 7378. 2. BMY 7378 inhibited [3H]-prazosin binding to aortic membranes with a potency (pKi 9.8 +/- 0.40) approximately 100 fold higher than in right ventricular membranes (pKi 7.47 +/- 0.11) and approximately 1,000 fold higher than that in plasma membranes of the prostate (pKi 6.62 +/- 0.39), vas deferens (pKi 6.67 +/- 0.15), salivary gland (pKi 6.46 +/- 0.38) and liver (6.58 +/- 0.06). 3. BMY 7378 antagonized the positive inotropic effects of phenylephrine (in the presence of 1 microM propranolol) on right ventricles (pA2 7.0 +/- 0.11), left atria (pKB 7.04 +/- 0.18) and papillary muscles (pKB 6.9 +/- 0.1) and inhibited phenylephrine-induced increase in inositol phosphates. 4. BMY 7378 was approximately 100 fold more potent as an antagonist of phenylephrine on aortic strips (pA2 9.0 +/- 0.13) than on vas deferens (pKB 7.17 +/- 0.08) and spleen (pKB 7.16 +/- 0.21); it was ineffective on the prostate. 5. Chloroethylclonidine suppressed the maximal effects of phenylephrine on spleen; 5-methylurapidil antagonized the effects of phenylephrine on aortic strips (pA2 7.98 +/- 0.08), vas deferens (pKB 8.89 +/- 0.07) and prostate (pKB 8.85 +/- 0.21). 6. BMY 7378 caused a dose (0.1-100 nmol kg-1)-dependent decrease in mean blood pressure of urethane-anaesthetized rats and its hypotensive efficacy was equal to that of hexamethonium. 7. The data suggest that alpha 1D-adrenoceptors play a significant role in rat aorta, a minor role in the heart, vas deferens and spleen and virtually no role in the prostate.

The enzymatic activity of Drosophila AWD/NDP kinase is necessary but not sufficient for its biological function

The Drosophila abnormal wing discs (awd) gene encodes the subunit of a protein that has nucleoside diphosphate kinase (NDP kinase) activity. Null mutations of the awd gene cause lethality after puparium formation. Larvae homozygous for such mutations have small imaginal discs, lymph glands, and brain lobes. Neither the imaginal discs nor the ovaries from such null mutant larvae are capable of further growth or normal differentiation when transplanted into suitable host larvae. This null mutant phenotype can be entirely rescued by one copy of a transgene that has 750 bp of awd upstream regulatory DNA fused to a full-length awd cDNA. Tissue-specific expression of AWD protein from this rescue transgene is identical to tissue-specific expression of beta-galactosidase from a reporter transgene that has the same regulatory region fused to the bacterial lac Z gene. However, this rescue transgene or reporter transgene expression pattern is only a subset of the endogenous pattern of expression detected by either in situ hybridization or immunohistochemistry. This suggests that awd is normally expressed in some tissues where it is not required. The null mutant phenotype cannot be rescued at all by a transgene that has 750 bp of awd upstream regulatory DNA fused to a full-length awd cDNA with a mutation that eliminates NDP kinase activity by replacement of the active site histidine with alanine. This suggests that the enzymatic activity of the AWD protein is necessary for its biological function. The human genes nm23-H1 and nm23-H2 encode NDP kinase A and B subunits, respectively. The protein subunit encoded by either human nm23 gene is 78% identical to that encoded by the Drosophila awd gene. Transgenes that have the 750-bp awd upstream regulatory DNA fused to human nm23-H2 cDNA but not to nm23-H1 cDNA can rescue the imaginal disc phenotype and the zygotic lethality caused by homozygosis for an awd null mutation as efficiently as an awd transgene. However, rescue of female sterility requires twice as much nm23-H2 expression as awd expression. This implies that the enzymatic activity of the AWD protein is not sufficient for its biological function. The biological function may require nonconserved residues of the AWD protein that allow it to interact with other proteins.

Ontogenic differences in the functions of myocardial alpha1 adrenoceptor subtypes in rats

The present study was done to determine possible ontogenic differences in the functions of rat myocardial alpha1, adrenoceptor (alpha1 AR) subtypes in view of reported greater inotropic responses of myocardium of neonatal than of adult rats to alpha1, AR agonists. Methoxamine, phenylephrine and norepinephrine were used as alpha1 AR agonists. Phenylephrine and norepinephrine were used in the presence of 3 microM propranolol. It was found that the ratios of chloroethylclonidine (CEC)-insensitive alpha1 AR subtype (alpha1A AR) to CES-sensitive alpha, AR subtype (alpha1B AR) were approximately 50:50 in neonatal (1 week old) and 20:80 in adult rat ventricles. alpha1A AR selective antagonists WB 4101 and 5-methylurapidil+ (5-MU) inhibited the inotropic effects of alpha1, AR agonists both on neonatal and on adult rat ventricles; in contrast, selective inactivation of alpha1B AR by CEC inhibited the inotropic effects of alpha1 AR agonists only on ventricles from adult but not from neonatal animals. WB 4101 inhibited methoxamine-induced increases in inositol phosphates by ventricular slices from both adult and neonatal rats; in contrast, CEC inhibited these effects of methoxamine only in tissues from adult but not in tissues from neonatal animals. In conclusion, this study, to our knowledge, demonstrates for the first time that the effects of alpha AR agonists on right ventricular contractions and phosphoinositol turnover are mediated primarily by alpha 1A AR subtype in the neonatal and by both alpha1A AR and alpha1B AR subtypes in the adult rat.

Point mutations in awdKpn which revert the prune/Killer of prune lethal interaction affect conserved residues that are involved in nucleoside diphosphate kinase substrate binding and catalysis

The awd gene of Drosophila melanogaster encodes a nucleoside diphosphate kinase. Killer of prune (Kpn) is a mutation in the awd gene which substitutes Ser for Pro at position 97 and causes dominant lethality in individuals that do not have a functional prune gene. This lethality is not due to an inadequate amount of nucleoside diphosphate (NDP) kinase activity. In order to understand why the prune/Killer of prune combination is lethal, even in the presence of an adequate NDP kinase specific activity level, and to understand the biochemical basis for the conditional lethality of the awdKpn mutation, we generated second site mutations which revert this lethal interaction. All of the 12 revertants we recovered are second site mutations of the awdKpn gene. Three revertants have deletions of the awdKpn protein coding region. Two revertants have substitutions of the initiator methionine and do not accumulate KPN protein. Seven revertants have amino acid substitutions of conserved residues that are likely to affect the active site: five of these have no enzymatic activity and two have a very low level of specific activity. These data suggest that an altered NDP kinase activity is involved in the mechanism underlying the conditional lethality of the awdKpn mutation.

Characterization of the vasorelaxant activity of tyramine and other phenylethylamines in rat aorta

We recently reported that tyramine caused concentration-dependent relaxation of rat aorta, which was endothelium independent and was not exerted via alpha 1-adrenoceptors (AR), alpha 2AR, beta 1AR, beta 2AR, or receptors for 5-hydroxytryptamine, histamine, and adenosine. The present studies were done on endothelium-denuded strips to determine structure-vasorelaxant activity after blockade of beta AR by propranolol plus irreversible blockade of alpha 1AR with benextramine. Vasorelaxation under these conditions was limited to noncatecholamines, and their vasorelaxant potencies were methoxyphenamine > tyramine > p-hydroxyephedrine > L-amphetamine > L-ephedrine > phenylethylamine > synephrine > methoxamine > octopamine. beta 3AR agonists (BRL 37344 and CGP 12177A) did not produce vasorelaxation, although tyramine could compete for cyanopindolol binding to murine L cells expressing human beta 2AR or beta 3AR. There was no significant specific binding of [3H]tyramine to aortic membrane preparations after the inhibition of monamine oxidase. Yohimbine, which has a high affinity for Drosophila tyramine receptors, also caused dose-dependent vasorelaxation like tyramine. It is concluded that tyramine and several other phenylethylamines produce relaxation of rat aorta, which does not involve any of the known adrenoceptors but may be exerted via novel tyramine receptors.