In vitro contractile activity of porcine myometrium during luteolysis and early pregnancy: effect of oxytocin and progesterone

The present study was undertaken to elucidate the role of OT in myometrial contractility in sows. Spontaneous and OT-stimulated contractions of the inner circular (CM) and outer longitudinal (LM) layers isolated from cyclic (Days 14-16) and early pregnant (Days 14-16) sows were examined in six cyclic and six pregnant sows. In addition, the role of P(4) in the modulation of OT-induced uterine contractions was investigated. The contractile activity of the LM and CM layers was recorded in a tissue chamber filled with Krebs-Ringer solution. Myometrial contractility was expressed as area under the contractility curve (AUC) and frequency of contractions. Myometrial longitudinal and circular muscles exhibited spontaneous contractility in sows during both luteolysis and early-pregnancy. The mean AUC was higher (p<0.05) in the LM layer compared to the CM layer in both cyclic and pregnant animals. In addition, pregnant sows were characterized by higher AUC in both LM and CM layers in comparison to cyclic sows. The CM layer was unresponsive to examined treatments. Oxytocin (1-3x10(-8) and 1-3x10(-7)M) increased the AUC and frequency of contractions of the LM layer in both examined animal groups, being more effective during luteolysis (p<0.001) than early pregnancy (p<0.01). Response of the LM layer to OT appeared to be clearly related to the initial spontaneous level of contractility. This response to OT was inhibited (p<0.05) in the presence of OT antagonist (10(-6)M). Moreover, in pregnant sows, OT-stimulated contractile activity of myometrium was inhibited (p<0.05) by P(4) (10(-5)M). In conclusion, OT receptors present in myometrial cells (especially in the LM layer) are involved in the regulation of contractile activity of porcine myometrium during luteolysis and early-pregnancy. In addition, progesterone appears to be involved in this regulation.     

Childhood asthma on the northern Mexico border

Children with asthma living on the northern Mexico border suffer not only from the physical aspects of this condition, but also from the lack of a clear biomedical definition and treatment plan for the illness. An ethnographic study involving participant observation and focused interviews in Tijuana, Mexico, sought to understand the intersection of diagnostic uncertainties surrounding childhood asthma on the part of parents, particularly mothers, living in acute poverty. Environmental factors such as dust and insects in impoverished homes probably acted as asthma triggers among many of the children in the study. Furthermore, management of children's asthma took place not only in biomedical clinics, but also in homes, traditional medical settings, and pharmacies, where mothers often sought remedies for their children's asthma attacks on an emergency basis. In all treatment settings, including biomedical ones, they often faced significant barriers to effective care, including the misuse of antibiotics. Thus, the role of pharmaceutical sales clerks, as well as pediatric asthma specialists, is explored in this article.     

Excision and transposition of two Ds transposons from the bronze mutable 4 derivative 6856 allele of Zea mays L

Summary The regulatory mutation bronze mutable 4 Derivative 6856 (bz-m4 D6856) contains a complex 6.7 kb Dissociation (Ds) element tagged with a duplication of low copy bz 3 flanking sequences (Klein et al. 1988). This creates a unique opportunity to study the transposition of a single member of the repetitive family of Ds elements. Eighteen full purple revertants (Bz alleles) of bz-m4 were characterized enzymatically and by genomic mapping. For 17 of the Bz alleles, reversion to a wild-type phenotype was caused by excision of the 6.7 kb Ds transposon. Nine of these Bz alleles retained the transposon somewhere in their genome. In this study we show that like Ac (Schwartz 1989; Dooner and Belachew 1989), the 6.7 kb Ds element can transpose within a short physical distance, both proximal and distal to its original position. Additional bz sequences have been mapped immediately distal to the mutant locus in bz-m4 D6856; genetic evidence suggests these are flanked by two additional Ds elements. The remaining Bz revertant, Bz :107, arose from excision of a more complex 13 kb Ds element.     

The Cerebrocortical Areas in Normal Brain Aging and in Alzheimer's Disease: Noticeable Differences in the Lipid Peroxidation Level and in Antioxidant Defense

The markers of oxidative stress were measured in four cerebrocortical regions of Alzheimer's disease (AD) and age-matched control brains. In controls the levels of diene conjugates (DC) and lipid peroxides (LOOH) were significantly higher in the sensory postcentral and occipital primary cortex than in the temporal inferior or frontal inferior cortex. The antioxidant capacity (AOC) was highest in the temporal, and GSH in the frontal inferior cortex. The highest activity of superoxide dismutase (SOD) and catalase (CAT) was found in the occipital primary cortex. Compared with controls, significantly higher level of DC and LOOH and attenuated AOC were evident in AD temporal inferior cortex. In AD frontal inferior cortex moderate increase in LOOH was associated with positive correlation between SOD activity and counts of senile plaques. Our data suggest that in AD cerebral cortex, the oxidative stress is expressed in the reducing sequence: temporal inferior cortex > frontal inferior cortex > sensory postcentral cortex occipital primary cortex, corresponding to the histopathological spreading of AD from the associative to primary cortical areas.     

Control of pollen-mediated gene flow in transgenic trees

Pollen elimination provides an effective containment method to reduce direct gene flow from transgenic trees to their wild relatives. Until now, only limited success has been achieved in controlling pollen production in trees. A pine (Pinus radiata) male cone-specific promoter, PrMC2, was used to drive modified barnase coding sequences (barnaseH102E, barnaseK27A, and barnaseE73G) in order to determine their effectiveness in pollen ablation. The expression cassette PrMC2-barnaseH102E was found to efficiently ablate pollen in tobacco (Nicotiana tabacum), pine, and Eucalyptus (spp.). Large-scale and multiple-year field tests demonstrated that complete prevention of pollen production was achieved in greater than 95% of independently transformed lines of pine and Eucalyptus (spp.) that contained the PrMC2-barnaseH102E expression cassette. A complete pollen control phenotype was achieved in transgenic lines and expressed stably over multiple years, multiple test locations, and when the PrMC2-barnaseH102E cassette was flanked by different genes. The PrMC2-barnaseH102E transgenic pine and Eucalyptus (spp.) trees grew similarly to control trees in all observed attributes except the pollenless phenotype. The ability to achieve the complete control of pollen production in field-grown trees is likely the result of a unique combination of three factors: the male cone/anther specificity of the PrMC2 promoter, the reduced RNase activity of barnaseH102E, and unique features associated with a polyploid tapetum. The field performance of the PrMC2-barnaseH102E in representative angiosperm and gymnosperm trees indicates that this gene can be used to mitigate pollen-mediated gene flow associated with large-scale deployment of transgenic trees.     

Evaluation of Postharvest-Processed Oysters by Using PCR-Based Most-Probable-Number Enumeration of Vibrio vulnificus Bacteria

Postharvest processing (PHP) is used to reduce levels of Vibrio vulnificus in oysters, but process validation is labor-intensive and expensive. Therefore, quantitative PCR was evaluated as a rapid confirmation method for most-probable-number enumeration (QPCR-MPN) of V. vulnificus bacteria in PHP oysters. QPCR-MPN showed excellent correlation (R² = 0.97) with standard MPN and increased assay sensitivity and efficiency.     

Frankia KB5 Possesses a Hydrogenase Immunologically Related to Membrane-Bound [NiFe]-Hydrogenases

The immunological relationship of the hydrogenase in Frankia KB5 to hydrogenases in other microorganisms was investigated using antisera raised against holo-[NiFe]-hydrogenases isolated from Alcaligenes latus, Azotobacter vinelandii, Ralstonia eutropha, and the small and large hydrogenase subunits from Bradyrhizobium japonicum. The antisera raised against the A. latus, R. eutropha, and B. japonicum (large subunit) polypeptides were found to recognize two polypeptides, corresponding to the unprocessed and processed forms of the hydrogenase subunit in Frankia KB5. None of the antisera, including the antibodies produced against the small hydrogenase subunit isolated from B. japonicum, recognized any polypeptide related to the small hydrogenase subunit in Frankia KB5. An immunogold localization study of the intracellular distribution of hydrogenase in Frankia KB5, with the cryo-section technique, showed that labeling in the membrane of both hyphae and vesicles was positively correlated with hydrogenase activity. Received: 6 November 2000 / Accepted: 18 December 2000     

Qualitative mathematical discussion of different evolutionary states in water transport systems of plants

We shall present several qualitative mathematical models to describe the early evolution of water transport systems in plants. To perform this in a systematic way we apply methods which have been developed in phenomenological synergetics. These methods rest on the fact that it becomes possible to describe the macroscopic behavior of a complex system by a set of control and order parameters when they are suitably identified. Our presentation is addressed to community with interdisciplinary interests.     

Factors involved in capillary growth in the heart

Growth of capillaries in the heart occurs under physiological circumstances during endurance exercise training, exposure to high altitude and/or cold, and changes in cardiac metabolism or heart rate elicited by modification of thyroid hormone levels. Capillary growth in all these conditions can be linked with increased coronary blood flow, decreased heart rate, or both. This paper brings evidence that, although increased blood flow due to long-term administration of coronary vasodilators results in capillary growth, a long-term decrease in heart rate induced by electrical bradycardial pacing in rabbits and pigs, or by chronic administration of a bradycardic drug, alinidine, in rats, stimulates capillary growth with little or no change in coronary blood flow. Decreased heart rate results in increased capillary wall tension, increased end-diastolic volume and increased force of contraction, and thus stretch of the capillary wall. This could lead to release of various growth factors possibly stored in the capillary basement membrane. Correlation was found between capillary density (CD) and the levels of low molecular endothelial cell stimulating angiogenic factor (ESAF) both in rabbit and pig hearts with CD increased by pacing. There was no relation between expression of mRNA for basic fibroblast growth factor and CD in sham-operated and paced rabbit hearts. In contrast, mRNA for TGFß was increased in paced hearts, and the possible role of this factor in the regulation of capillary growth induced by bradycardia is discussed.