Juan J. Tarín

The sperm centriole: its inheritance, replication and perpetuation in early human embryos

The inheritance, replication and perpetuation of the sperm centriole in the early human embryo are reported. Both normal monospermic and abnormal dispermic embryos (n = 127) were examined by transmission electron microscopy. Centrioles were traced from fertilization to the hatching blastocyst stage. The sperm proximal centriole is introduced into the oocyte at fertilization and remains attached to the expanding spermhead during sperm nuclear decondensation, as it forms the male pronucleus. A sperm aster is initially formed after the centriole duplicates at the pronuclear stage. At syngamy, centrioles occupy a pivotal position on opposite spindle poles, when the first mitotic figure is formed. Bipolar spindles were found in the majority of embryos, while tripolar spindles were seen in four dispermic embryos at syngamy. Two single centrioles were detected at two poles of two tripolar spindles, while two additional centrioles were located on the sides of a bipolar spindle of a dispermic embryo. Sperm tails were detected near spindle poles at syngamy and in later embryos. Typical centrioles showing the characteristic pin-wheel organization of nine triplets of microtubules were evident. During centriolar replication, the daughter centriole grows laterally from the parent and gradually acquires pericentriolar material (PCM). The two centrioles are surrounded by a halo of electron-dense PCM, which nucleates microtubules, thus making it a typical centrosome. The usual alignment of diplosomes at right angles to each other was maintained. Centrioles were detected at all stages of embryonic cleavage from the 1-cell through 8-cell stages, right up to the hatching blastocyst stage. They were closely associated with nuclei at interphase, when they were often replicating, and were prominently located at spindle poles during the first four cell cycles. In blastocysts, they were detected in trophoblast, embryoblast and endoderm cells respectively. It is evident that the sperm centrosome is the functional active centrosome in human, while the female is inactive but may contribute some centrosomal material to the zygote centrosome. It is very likely that the paternal centriole is the ancestor of the centrioles in fetal and adult somatic cells.

The impact of coffee on health

OBJECTIVE Coffee is a beverage used worldwide. It includes a wide array of components that can have potential implication on health. We have reviewed publications on the impact of coffee on a series of health outcomes. METHODS Articles published between January 1990 and December 2012 were selected after crossing coffee or caffeine with a list of keywords representative of the most relevant health areas potentially affected by coffee intake. RESULTS Caffeine, chlorogenic acids and diterpenes are important components of coffee. Tolerance often acts as a modulator of the biological actions of coffee. There is a significant impact of coffee on the cardiovascular system, and on the metabolism of carbohydrates and lipids. Contrary to previous beliefs, the various forms of arterial cardiovascular disease, arrhythmia or heart insufficiency seem unaffected by coffee intake. Coffee is associated with a reduction in the incidence of diabetes and liver disease. Protection seems to exist also for Parkinsons disease among the neurological disorders, while its potential as an osteoporosis risk factor is under debate. Its effect on cancer risk depends on the tissue concerned, although it appears to favor risk reduction. Coffee consumption seems to reduce mortality. CONCLUSION The information gathered in recent years has generated a new concept of coffee, one which does not match the common belief that coffee is mostly harmful. This view is further supported by the discovery of a series of phyto-components with a beneficial profile. Reasonable optimism needs to be tempered, however, by the insufficiency of the clinical data, which in most cases stem from observational studies.

Cell cycle: Aetiology of age-associated aneuploidy: a mechanism based on the ‘free radical theory of ageing’

A general model is put forward to explain the mechanism by which age-associated aneuploidies are produced. This is based on the free radical theory of ageing, which assumes a rise in oxidative stress with age. It is proposed that determination of indicators of oxidative stress in oocytes from various sources could be a first step in the testing of this hypothesis.

Cellular and Morphological Traits of Oocytes Retrieved from Aging Mice after Exogenous Ovarian Stimulation

Abstract The present study aims to shed light on the origin of abnormal oocytes ovulated by aged females. In order to reach this goal, cellular and morphological traits of ovulated oocytes from hybrid (C57Bl/6JIco female × CBA/JIco male) female mice retrieved after exogenous ovarian stimulation at the age of 12, 40–42, 50–52, or 57–62 wk were analyzed. Aging of female mice was associated with 1) decreased number of ovulated oocytes; 2) increased percentage of cumulus-free oocytes; 3) raised percentage of oocytes with intracellular mitochondrial aggregates; 4) reduced percentage of oocytes displaying a normal distribution of chromosomes in the metaphase-II plate; 5) increased percentage of normal oocytes exhibiting a DNA-containing polar body (PB); 6) higher percentage of oocytes with chromosome scattering; 7) increased percentage of chromosome-scattered oocytes without a DNA-containing PB and with intracytoplasmic mitochondrial aggregates; 8) raised percentage of oocytes exhibiting chromosome decondensation; 9) lower percentage of chromosome-decondensed oocytes lacking both a DNA-containing PB and intracytoplasmic mitochondrial aggregates; 10) increased percentage of abnormal/degenerated oocytes; 11) reduced percentage of abnormal/degenerated oocytes displaying cellular fragmentation; and 12) higher percentage of abnormal/degenerated oocytes with mitochondrial aggregates exhibiting no nuclear/chromosomal DNA fluorescence, cellular fragmentation, milky or dark cytoplasm, or cellular remains enclosed by the zona pellucida. Although several studies suggest aging females may ovulate aged or overripened oocytes, these data support the hypothesis that old females ovulate an increased percentage of atretic/apoptotic oocytes coming from rescued follicles that would have become atretic earlier in life.

The impact of chocolate on cardiovascular health

Cardiovascular disease is the leading determinant of mortality and morbidity in women. Functional foods are attracting interest as potential regulators of the susceptibility to disease. Supported by epidemiological evidence, chocolate has emerged as a possible modulator of cardiovascular risk. Chocolate, or cocoa as the natural source, contains flavanols, a subclass of flavonoids. The latter years have witnessed an increasing number of experimental and clinical studies that suggest a protective effect of chocolate against atherogenesis. Oxidative stress, inflammation, and endothelial function define three biological mechanisms that have shown sensitivity to chocolate. Moreover, the consumption of chocolate has been involved in the protective modulation of blood pressure, the lipid profile, the activation of platelets, and the sensitivity to insulin. Dark chocolate seems more protective than milk or white chocolate. Despite this array of benefits, there is a lack of well designed clinical studies demonstrating cardiovascular benefit of chocolate. The high caloric content of chocolate, particularly of some less pure forms, imposes caution before recommending uncontrolled consumption.

Estradiol selectively stimulates endothelial prostacyclin production through estrogen receptor-α

Estradiol (E(2)) acts on the endothelium to promote vasodilatation through the release of several compounds, including prostanoids, which are products of arachidonic acid metabolism. Among these, prostacyclin (PGI2) and thromboxane A2 (TXA2) exert opposite effects on vascular tone. The role of different estrogen receptors (ERs) in the PGI2/TXA2 balance, however, has not been fully elucidated. Our study sought to uncover whether E(2) enhances basal production of PGI2 or TXA2 in cultured human umbilical vein endothelial cells (HUVECs), to analyze the enzymatic mechanisms involved, and to evaluate the different roles of both types of ERs (ERalpha and ERbeta). HUVECs were exposed to E(2), selective ERalpha (1,3,5-tris(4-hydroxyphenyl)-4-propyl-1h-pyrazole, PPT) or ERbeta (diarylpropionitrile, DPN) agonists and antagonists (unspecific: ICI 182 780; specific for ERalpha: methyl-piperidino-pyrazole, MPP). PGI2 and TXA2 production was measured by ELISA. Expression of phospholipases, cyclooxygenases (COX-1 and COX-2), PGI2 synthase (PGIS), and thromboxane synthase (TXAS) was analyzed by western blot and quantitative RT-PCR. E(2) (1-100 nM) dose dependently increased PGI2 production (up to 50%), without affecting TXA2 production. COX-1 and PGIS protein and gene expressions were increased, whereas COX-2, phospholipases, and TXAS expression remained unaltered. All these effects were mediated through ERalpha, since they were produced not only in the presence of E(2), but also in that of PPT, while they were abolished in the presence of MPP. In conclusion, E(2), acting through ERalpha, up-regulates COX-1 and PGIS expression, thus directing prostanoid balance toward increased PGI2 production.

Postovulatory Aging of Oocytes Decreases Reproductive Fitness and Longevity of Offspring

Abstract We analyzed the long-term effects of postovulatory aging of mouse oocytes on reproductive fitness and longevity of offspring. Hybrid (C57BL/6JIco × CBA/JIco) parental generation (F0) females were artificially inseminated at 13 h (∼1 h postovulation) or 22 h (∼10 h postovulation) after GnRH injection. Reproductive fitness of first generation (F1) females was tested from the age of 28 wk until the end of their reproductive life. In males, the testing period ranged from the age of 2 yr until their natural death. Experimental F1 females exhibited longer between-labor intervals, decreased frequency of litters, and lower total number of litters and offspring born. Experimental second generation (F2) pups displayed teratogenic defects, higher preweaning mortality, and decreased body weight at weaning. Incidence of infertility was higher in experimental F1 males, which translated into lower total number of offspring born when compared with the control group. Life expectancy of F1 offspring was decreased in the experimental group. These results clearly show that postovulatory aging of mouse oocytes decreases reproductive fitness and longevity of offspring.

Effects of aging on the human ovary: the secretion of immunoreactive α-inhibin and progesterone

Objective To investigate the changes induced by age in the function and secretory pattern of the human ovary. Immunoreactive α -inhibin, E 2 , and P secretion in vivo and in vitro have been compared in two different populations. Design Prospective study. Women undergoing IVF-ET were divided into two groups according to age: group 1 (32.0±0.7years; mean±SEM) and group 2 (40.3±0.3years). Setting In vitro fertilization program at the Instituto Valenciano de Infertilidad. Patients A total of 33 infertile women with regular menses, undergoing IVF-ET. Interventions Follicle aspiration performed by transvaginal ultrasound. Four follicles per patient were aspirated in individual plastic tubes. Granulosa-luteal cells isolated with Percoll columns and cultured in vitro up to 4days in the presence of hCG. Main Outcome Measures In vitro fertilization parameters, serum levels of E 2 , immunoreactive α -inhibin, and P, as well as the secretion of immunoreactive α -inhibin and P by the cultured granulosa-luteal cells. Results Serum immunoreactive α -inhibin levels the day of ovum pick-up were significantly lower in group 2 compared with group 1. Incubation of cells for 96hours showed a significantly higher ability to accumulate immunoreactive α -inhibin in group 1 than 2. Human chorionic gonadotropin stimulated immunoreactive α -inhibin production after 96hours. Cells from younger women displayed a significantly higher ability to secrete P than cells from older women. Human chorionic gonadotropin was able to significantly stimulate P production in group 1. Conclusions These results confirm previous observations showing a reduced production of immunoreactive α -inhibin and steroids of ovaries from older women and suggest that a reduced cellular function, rather than a decrease in the follicular population, is the main mechanism by which these changes are produced.

Isoflavones and cardiovascular disease.

The specific profile of estrogens on cardiovascular risk, with limiting action on atherogenesis but a less clear protection on cardiovascular episodes, might be improved by other agonists of the estrogen receptor, such as isoflavones. By using a systematic search based on the electronic Medline database plus a hand-search of reference lists of selected review papers, we reviewed the rapidly growing body of experimental and clinical data that, on average, follow a pattern of benefit rather similar to estrogens. Experimental models have used endothelial and vascular smooth muscle cells, isolated arteries, and live animals, including monkeys. The clinical evidence arises from studies on the lipid profile and lipid oxidation, insulin resistance, hemostasis, changes in the inflammatory factors, and indicators of endothelial function, including metabolites of nitric oxide and prostacyclin. There are not randomized trials investigating the action of isoflavones on the incidence of clinical episodes, but a few recent, well-designed studies have suggested the association of the ingestion of isoflavones with a reduction in the atherosclerotic burden, as indicated by the measurement of the intima-media thickness in carotid vessels.

Effect of menopause and different combined estradiol-progestin regimens on basal and growth hormone-releasing hormone–stimulated serum growth hormone, insulin-like growth factor-1, insulin-like growth factor binding protein (IGFBP)-1, and IGFBP-3 levels

OBJECTIVE To determine the effects of menopause and three different formulations of E2 plus medroxyprogesterone acetate on serum concentrations of basal and growth hormone-releasing hormone (GHRH)-stimulated growth hormone (GH), insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein (IGFBP)-1, IGFBP-3, insulin, and C peptide. DESIGN Prospective, controlled trial. SETTING Menopausal outpatient clinic at an academic tertiary care hospital. PATIENT(S) Nineteen postmenopausal women with different menopausal ages. Seventeen premenopausal women were included as controls. INTERVENTION(S) Oral estrogen (E2 valerate, 2 mg/d) or transdermal estrogen (50-microg or 100-microg E2 patch) was administered for 8 weeks. Medroxyprogesterone acetate (5 mg/d) was administered during weeks 3, 4, 7, and 8 of each protocol. Blood samples were collected before treatment and after the completion of each protocol from postmenopausal women, and on cycle days 6-8 from premenopausal women. MAIN OUTCOME MEASURE(S) Levels of GH, IGF-1, IGFBP-1, IGFBP-3, insulin, and C peptide. RESULT(S) Basal GH levels were negatively correlated with age in premenopausal women but not in postmenopausal women. The area under the GHRH-induced GH curve decreased in older postmenopausal women after the oral estrogen protocol. Levels of IGF-1 diminished after the oral E2 protocol in postmenopausal women. CONCLUSION(S) The administration of oral, but not transdermal, E2 plus medroxyprogesterone acetate at the usual clinical doses used in postmenopausal women decreased IGF-1 levels and the response of GH to GHRH in older women. No substantial changes were detected in IGFBP-1, IGFBP-3, insulin, or C peptide levels.