Experimental Biology and Medicine

Conventional treatment approaches for malignant tumors are highly invasive and sometimes have only a palliative effect. Therefore, there is an increasing demand to develop novel, more efficient treatment options. Increased efforts have been made to apply immunomodulatory strategies in antitumor treatment. In recent years, immunizations with naked plasmid DNA encoding tumor-associated antigens have revealed a number of advantages. By DNA vaccination, antigen-specific cellular as well as humoral immune responses can be generated. The induction of specific immune responses directed against antigens expressed in tumor cells and displayed e.g., by MHC class I complexes can inhibit tumor growth and lead to tumor rejection. The improvement of vaccine efficacy has become a critical goal in the development of DNA vaccination as antitumor therapy. The use of different DNA delivery techniques and coadministration of adjuvants including cytokine genes may influence the pattern of specific immune responses induced. This brief review describes recent developments to optimize DNA vaccination against tumor-associated antigens. The prerequisite for a successful antitumor vaccination is breaking tolerance to tumor-associated antigens, which represent “self-antigens.” Currently, immunization with xenogeneic DNA to induce immune responses against self-molecules is under intensive investigation. Tumor cells can develop immune escape mechanisms by generation of antigen loss variants, therefore, it may be necessary that DNA vaccines contain more than one tumor antigen. Polyimmunization with a mixture of tumor-associated antigen genes may have a synergistic effect in tumor treatment. The identification of tumor antigens that may serve as targets for DNA immunization has proceeded rapidly. Preclinical studies in animal models are promising that DNA immunization is a potent strategy for mediating antitumor effects in vivo. Thus, DNA vaccines may offer a novel treatment for tumor patients. DNA vaccines may also be useful in the prevention of tumors with genetic predisposition. By DNA vaccination preventing infections, the development of viral-induced tumors may be avoided.

Under normal physiological conditions, coronary blood flow is closely matched with the rate of myocardial oxygen consumption. This matching of flow and metabolism is physiologically Important due to the limited oxygen extraction reserve of the heart. Thus, when myocardial oxygen consumption is increased, as during exercise, coronary vasodilation and increased oxygen delivery are critical to preventing myocardial underperfusion and Ischemia. Exercise coronary vasodilation is thought to be mediated primarily by the production of local metabolic vasodilators released from cardiomyocytes secondary to an increase in myocardial oxygen consumption. However, despite various investigations into this mechanism, the medlator(s) of metabolic coronary vasodilation remain unknown. As will be seen in this review, the adenosine, K+ATP channel and nitric oxide hypotheses have been found to be inadequate, either alone or in combination as multiple redundant compensatory mechanisms. Prostaglandins and potassium are also not important in steady-state coronary flow regulation. Other factors such as ATP and endothelium-derived hyperpolarizing factors have been proposed as potential local metabolic factors, but have not been examined during exercise coronary vasodilation. In contrast, norepinephrine released from sympathetic nerve endings mediates a feed-forward ß-adrenoceptor coronary vasodilation that accounts for -25% of coronary vasodilation observed during exercise. There is also a feed-forward α-adrenoceptor-mediated vasoconstriction that helps maintain blood flow to the vulnerable subendocardium when heart rate, myocardial contractility, and oxygen consumption are elevated during exercise. Control of coronary blood flow during pathophysiological conditions such as hypertension, diabetes mellitus, and heart failure is also addressed.

We determined the roles of maximal systolic elastance (Emax) and theoretical maximum flow (Q_max) in the regulation of cardiac pumping function in early streptozotocin (STZ)-diabetic fats. Physically, Emax can reflect the intrinsic contractility of the myocardium as an intact heart, and Q_max has an inverse relation to the systolic resistance of the left ventricle. Rats given STZ 65 mg/kg l.v. (n = 17) were divided into two groups, 1 week and 4 weeks after induction of diabetes, and compared with untreated age-matched controls (n = 15). Left ventricular (LV) pressure and ascending aortic flow signals were recorded to calculate Emax and Q_max, using the elastance-resistance model. After 1 or 4 weeks, STZ-diabetic animals show an increase in effective LV end-diastolic volume (Veed), no significant change in peak iso-volumic pressure (Pisomax), and a decline in effective arterial volume elastance (Ea). The maximal systolic elastance Emax is reduced from 751.5 ± 23.1 mmHg/ml in controls to 514.1 ± 22.4 mmHg/ml in 1- and 538.4 ± 33.8 mmHg/ml in 4-week diabetic rats. Since Emax equals PisomaxVeed, an increase in Veed with unaltered Pisomax may primarily act to diminish Emax so that the intrinsic contractility of the diabetic heart is impaired. By contrast, STZ-diabetic rats have higher theoretical maximum flow Q_max (40.9 ± 2.8 ml/s in 1- and 44.5 ± 3.8 ml/s in 4-week diabetic rats) than do controls (30.7 ± 1.7 ml/s). There exists an inverse relation between Q_max and Ea when a linear regression of Q_max on Ea is performed over all animals studied (r= 0.65, p < 0.01). The enhanced Q_max is indicative of the decline in systolic resistance of the diabetic rat heart. The opposing effects of enhanced Q_max and reduced Emax may negate each other, and then the cardiac pumping function of the early STZ-diabetic rat heart could be preserved before cardiac failure occurs.

The role of ethanol or its metabolites on breast neoplasm has not been characterized. We hypothesized that ethanol may alter the growth rate of human breast tumor epithelial cells by modulating putative growth-promoting signaling pathways such as p44/42 mitogen-activated protein kinases (MAPKs). The MCF-7 cell line, considered a suitable model, was used in these studies to investigate the effects of ethanol on [3H]thymidine incorporation, cell number, and p44/42 MAPK activities in the presence or absence of a MAPK or extracellular signal-regulated kinase ERK-1, and (MEK1) inhibitor (PD098059). Treatment of MCF-7 cells with a physiologically relevant concentration of ethanol (0.3% or 65 mM) increased p44/42 activities by an average of 400% (P < 0.02), and subsequent cell growth by 200% (P < 0.05) in a MEK1 inhibitor (PD098059)-sensitive fashion, thus suggesting that the Ras/MEK/MAPK signaling pathways are crucial for ethanol-induced MCF-7 cell growth.

The objective of this research was to compare the effects of a lean beef enriched in oleic acid to a beef that is typical of the commercial beef consumed in the United States. Ten mildly hypercholesterolemic men, ages 34-58 years old, were selected from the Texas A&M University faculty and staff. Subjects were randomly assigned to one of two diets for a 6-week duration followed by a crossover after a 4-week habitual diet washout period. Diets were consumed daily for a 6-week study period. Participants substituted lean beef obtained from Wagyu bullocks or commercial beef for the meat typically consumed. Total cholesterol, apolipoproteins A-I and B, triacylglycerols, and low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol were measured in serum samples collected weekly. Beef type had no effect on any measured variable. There were no significant differences between baseline HDL or LDL cholesterol concentrations after the consumption of the beef test diets. Apolipoprotein A-I, serum glucose, and uric acid concentrations were elevated by the additional dietary beef. Analysis of records of customary diets indicated that one group consumed 160 g of beef daily, whereas the other group consumed only 26 g of beef daily. Therefore, post hoc analyses tested the habitual beef intake x treatment time interaction. LDL cholesterol concentration was markedly higher in the group with low habitual beef Intake (180 vs 144 mg/dl), and HDL cholesterol was slightly higher (44 vs 40 mg/dl; post-test values) than for the group with high habitual beef intake, but there were no habitual intake x time interactions for LDL or HDL cholesterol. Creatinine and blood urea nitrogen concentrations also were greater in the individuals habitually consuming less beef. This study had three important findings: i) a lean beef source enriched with oleic acid was no different from commercial beef in its effect on lipoprotein fractions; ii) neither previous level of beef intake nor baseline LDL cholesterol concentration influenced the serum cholesterol response to added dietary beef. which was negative; and iii) apolipoprotein A-I, but not HDL or LDL cholesterol, was sensitive to the additional dietary beef.

Polyamines, putrescine (PUT), spermidine (SPD), spermine (SPM), and agmatine (AGM), are polycationic amines related to multiple cell functions found in high concentrations during the development of hypothalamus and pituitary. In previous works, we demonstrated that α-difluoromethylornithine (DFMO), an inhibitor of polyamines biosynthesis, induced a delay in puberty of female rats, accompanied by high, sustained follicle-stimulating hormone (FSH) levels during the infantile period. Also, DFMO treatment induced changes in polyamine concentration both in hypothalamus and pituitary of rats, mainly a decrease of PUT and SPD, an increase in SPM, and no change in AGM. In the present work, we investigated the direct effects of polyamines on the secretion of hypothalamic GnRH and pituitary gonadotropins in 6- and 15-day-old female rats. In 6-day-old animals, In vitro incubations with PUT, SPD, and AGM of hypothalami or anterior pituitaries were able to inhibit GnRH, FSH, and leutinlzing hormone (LH) secretion, respectively. SPM showed a nonspecific transient inhibitory effect on FSH. When challenged with either high K+ (hypothami) or GnRH (pituitaries), the tissues incubated in the presence of polyamines showed no differences when compared with their controls. No effects of polyamines in 15-day-old rats in either tissue were observed. Pituitary cell cultures of 6-day-old animals incubated with DFMO for 4 days showed a significant increase in FSH, but not in LH. We conclude that high PUT, SPD, and AGM levels during the first 10 days of life are important for the development of the hypothalamic-hypophyseal unit, probably related to an inhibitory effect on GnRH and gonadotropins. Therefore, polyamine participation, especially PUT and SPD, is of importance in the regulation of GnRH and gonadotropin secretion in the neonatal and infantile periods, critical stages in the establishment of sexual differentiation.

This work reports the effects of a previous injection of mitomycin-modified splenocytes from multiple-low dose streptozotocin-treated mice (mld-sz) on autoimmune diabetes produced by mld-sz. Our work shows that a previous inoculation of modified mononuclear splenocytes from mld-sz mice prevents alterations in glycemia, in insulin secretion (IS) pattern from isolated perifused islets, and in mass of pancreatic islets. Immunohistochemistry showed an alteration in the number of beta, but not of alpha or delta cells. While a mononuclear intra-islet infiltration was observed in mld-sz mice, a predominantly polar or peri-islet infiltration was seen in vaccinated mice. Islet-associated mononuclear cells from mld-sz mice produced diabetes and induced a diminished IS when transferred to normal receptors. Those cells from previously vaccinated mld-sz mice had no effect when injected into normal receptors. In addition, they also inhibited the damage induced in normal receptors by the islet-associated mononuclear cells from mld-sz animals. Cellular death was also prevented by previous vaccination. Our results suggest that vaccination with modified splenocytes from mld-sz mice is capable of shifting the islet cells infiltration pattern from an aggressive one toward a protective one and thus preventing the ß cell destruction observed in mld-sz mice.