By: Cathi E. Dennehy PharmD
The Preantral Follicle Once growth is accelerated buy aczone 100 mg low cost, the follicle progresses to order aczone 100mg on line the preantral stage as the oocyte enlarges and is surrounded by a membrane cheap aczone 100 mg online, the zona pellucida. The granulosa cells undergo a multilayer proliferation as the thecal layer continues to organize from the surrounding stroma. This growth is dependent upon gonadotropins and is correlated with increasing production of estrogen. Molecular studies indicate that all of the granulosa cells in mature follicles are derived from as 18 few as 3 precursor cells. The granulosa cells of the preantral follicle have the ability to synthesize all 3 classes of steroids; however, significantly more estrogens than either androgens or progestins are produced. An aromatase enzyme system acts to convert androgens to estrogens and is a factor limiting ovarian estrogen production. Although steroidogenesis in the ovarian follicle is mainly regulated by the gonadotropins, multiple signaling pathways are involved that respond to many factors besides the gonadotropins. Besides the adenylate cyclase enzyme system, these pathways include ion gate channels, tyrosine kinase receptors, and the phospholipase system of second messengers. As growth proceeds, the granulosa cells differentiate into several subgroups of different cell populations. This appears to be determined by the position of the cells relative to the oocyte. Cells with receptors can transfer a signal 24 (by gap junctions), which causes protein kinase activation in cells that lack receptors. Thus, hormone-initiated action can be transmitted throughout the follicle despite the fact that only a subpopulation of cells binds the hormone. This system of communication promotes a coordinated and synchronous performance throughout the follicle, a system that continues to operate in the corpus luteum. When exposed to an androgen-rich environment, 26 preantral granulosa cells favor the conversion of androgens to more potent 5a-reduced androgens rather than to estrogens. These androgens cannot be converted 27 28 to estrogen and, in fact, inhibit aromatase activity. At low concentrations, androgens enhance their own aromatization and contribute to estrogen production. Those follicles arising at the end of the luteal phase or early in the subsequent cycle would be favored by an environment in which aromatization in the granulosa cell can prevail. The success of a follicle depends upon its ability to convert an 30 androgen-dominated microenvironment to an estrogen-dominated microenvironment. The accumulation of follicular fluid provides a means whereby the oocyte and surrounding granulosa cells can be nurtured in a specific endocrine environment. The granulosa cells surrounding the oocyte are now 31 designated the cumulus oophorus. The differentiation of the cumulus cells is believed to be a response to signals originating in the oocyte. Antral follicles with the greatest rates of granulosa proliferation contain the highest estrogen concentrations and the lowest 34 androgen:estrogen ratios, and are the most likely to house a healthy oocyte. An androgenic milieu antagonizes estrogen-induced granulosa proliferation and, if sustained, promotes degenerative changes in the oocyte. The steroids present in follicular fluid can be found in concentrations several orders of magnitude higher than those in plasma and reflect the functional capacity of the 23, 29, 33, 35, 36 surrounding granulosa and theca cells. The synthesis of steroid hormones is functionally compartmentalized within the follicle—the two-cell system. The Two-Cell, Two-Gonadotropin System the aromatase activity of the granulosa far exceeds that observed in the theca. The interaction between the granulosa and theca compartments, with resulting accelerated estrogen production, is not fully functional until later in antral development. Like preantral granulosa cells, the granulosa of small antral follicles exhibits an in vitro tendency to convert significant amounts of androgen to the more potent 5a-reduced form. In contrast, granulosa cells isolated from large antral follicles readily and preferentially metabolize androgens to estrogens. The lipoproteins are not internalized, but rather, the cholesteryl esters are extracted from 40 the lipoproteins at the cell surface and then transferred into the cell. As the follicle emerges, the theca cells are characterized by their expression of P450c17, the enzyme step which is rate-limiting for the conversion of 21-carbon 41 substrate to androgens. Granulosa cells do not express this enzyme and thus are dependent upon androgens from the theca in order to make estrogen.
Therefore purchase aczone 100mg free shipping, some method is necessary to generic aczone 100mg on-line get blood back to discount aczone 100mg with amex the heart, especially from the lower regions of the body. The muscles around the veins produce a milking action of the veins forcing blood toward the heart. Approximately 90% of plasma is water, in which many substances are dissolved or suspended. White blood cells are composed largely of a substance that act as anti-bodies to assist in the fighting of disease and infections. The red blood cells are formed in the bone marrow and there are approximately 35 trillion total in the body. Each hemoglobin molecule within the red blood cell can carry 4 molecules of oxygen, so each red blood cell can carry approximately 1 billion oxygen molecules. The secret of hemoglobin is that it contains one atom of iron for every hemoglobin molecule. The red blood cells carry 95% of all oxygen, while the remainder is suspended in plasma. It can be readily seen that a person who is anemic, for example, does not have enough functioning red blood cells and will begin to suffer the effect of lack of oxygen at a relatively low altitude. The blood of the average person contains about 15 grams of hemoglobin per 100 ml (milliliter) of blood. Normal arterial saturation is about 95 97 % and the oxygen content is 19 volumes percent. The ability of hemoglobin to take up or release oxygen is not a linear function of the partial pressure. However, the relationship is well defined and is usually shown in the form of the oxygen dissociation curve. Venous or return blood has a normal oxygen tension of 40mm and contains 14 volume percent of oxygen, and is 65 75 % saturated. It gives the human body the capability to adjust and function in a variety of environments. Any aviator who flies above 12,000 feet in an unpressurized aircraft without supplemental oxygen is a potential hypoxia case. Anything that impedes the arrival or utilization of oxygen to the cell, places the body in a hypoxic state. There are many conditions that can interrupt the normal flow of oxygen to the cells. The following table describes the various levels at which hypoxia can occur: Location of Impediment Common Name Explanation Lungs Hypoxic Any condition that interrupts the flow Hypoxia of O2 into the lungs. This is the type of hypoxia encountered at altitude due to the reduction of the partial pressure of O2. Blood Hypemic Any condition that interferes with the Hypoxia ability of the blood to carry oxygen. Anemia and carbon monoxide poisoning are two conditions that can keep the O2 from attaching to the hemoglobin within the red blood cell. Blood Transport Stagnant Any condition that interferes with the Hypoxia normal circulation of the blood arriving to the cells. Heart failure, shock, and positive G force along the Z axis will bring about this condition. Cell Histotoxic Any condition that interferes with the Hypoxia normal utilization of O2 in the cell. While all cells require oxygen to function, some cells require more oxygen than others. The central nervous system (made up of the brain and spinal cord) do not have this ability and also demand a great deal of oxygen (approximately 20% of all oxygen that you inhale feeds the brain). So, if the oxygen supply to the body is reduced, the brain will be one of the first organs to be affected. Another problem is that when the brain starts to feel the effects of hypoxia, the higher reasoning portion of the brain is the first affected. Therefore, these signs should not be included with the personal symptoms one gets while experiencing hypoxia.
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He suggests males than females (Moore and Morelli generic aczone 100mg on-line, that men buy 100 mg aczone amex, subconsciously and from evolu 1979) generic aczone 100mg with amex. Such a “releaser” of testosterone in newborn males and fe allows morphological traits to reliably males (Moore, 1992). Lack of such anoge signal health and reproductive potential nital licking has been shown to alter adult (Singh, 1995). Similarly, other studies sug male copulatory performance; deprived gest that people who exhibit greater facial males demonstrated longer interintromis symmetry have an easier time finding wil sion times, ejaculatory latencies, and post ling sexual partners, and who— ejaculatory intervals (Moore, 1984). This surprisingly enough—also experience a tactile stimulus is believed crucial in many greater number of orgasms (Thornhill, subsequent aspects of reproductive deve Gangestad, and Corner, 1995). Many think such preferences are stimuli can influence sexual develop culturally induced and conditioned. MacLean (1985)examined the rele either case, if the links occur early enough vance of distinctive sounds to primate and at a nonvolitional level we might con behavior. He ally attractive to the majority of males and noted that audiovocal communication vice-versa, what makes males visually becomes of the utmost importance in attractive to the majority of females? We mammals for maintaining maternal hypothesize that the basic sexual attraction offspring contact. Such contact has been preference is established by the Gn–H–B shown to be important in the behavioral model but it may be modified by social development of many species. For examp and cultural input and, as well, by the ge le, Dizzino, Whitney, and Nyby nomic forces mentioned above. Thus, the infant develop sexually; particularly important is experience primes the individual for later the role of the mother. At havior may be an instance of classical con least some rat pups will mate well if left ditioning” (p. Nonetheless, it is generally ag to male and female and these social guides reed that what an animal hears may affect are generally followed. The sound of a come and go with changes in many activi predator may elicit fear and thus conceal ties, occupations, and sports considered ment or freezing behavior. It is conceded that soothing voice may not truly have the thesepatterns of behavior are highly malle power “to soothe a savage beast” but it able by society and external forces. It is not contrast, however, there is scant evidence clear how these behaviors develop. Intellectually, and with more than a bit of basic knowledge, one can envision ge There is polemic. Many such topics were sexual orientation, at least for lesbians, emphasized in the preceding sections. In and only polemic holds that one is “no tuitively, however, it seems easier to attri more driven by biology or subconscious bute behaviors to learned or major envi urges [toward heterosexual or homosexual ronmental and social factors. References to expression] than they are when, for ins many such environmental and social fac tance, they change jobs” (p. Freud’s works claims, there is no evidence we see oursel (1953, originally published 1905; 1971, ori ves as males or females because we are ginally published 1920) are often quoted to brought up in stereotypical blue or pink infer that major aspects of adult sexual rooms (see. More currently, popular scripting and sexual identity, that appear the most theory has purported that we behave fixed (Diamond, 1995, 1996, 1997a). It is sexually by following models we see in just these traits that are typically conside our surround (Gagnon and Simon, 1973), red organized prenatally and activated and much of the so-called “feminist” or with puberty. And for many, feelings of deconstructionist literature holds that being male or female develop despite be women and men are different mainly be ing reared in the other sex (Diamond, cause of social and cultural forces that 1996, 1997b; Diamond and Sigmundson, “construct” artificial differences (Foucault, 1997). These can be cal 1977) and with malnutrition (Rhees and led stresses and, in humans, at least, be of Fleming, 1981). In humans the (1992) describes this situation among ma situations might be anticipated to be les derived from the same litter of highly events that occurred prenatally or even inbred animals. Childhood events that cannot be recal mals, four distinct subgroups become evi led, such as those alleged to have occurred dent. Just what causes the variability and dissociations in behavioral potentials the work of Ingeborg Ward (1972) is among animals that all experienced the classic in its definitive demonstration that same prenatal treatment and are from the environmental stresses can influence the same litter is puzzling. Pregnant forces mentioned in earlier parts of this rats, after repeated strict confinement and article are involved. For would lordose when mounted by normal instance, prenatally stressed male mice males. Ward and Weisz (1984) found this (vom Saal, 1983) and rats (Miley, 1983) are stress was correlated with elevated corti less prone to kill pups and more likely to costeroid levels in both mothers and fetu show positive parental behaviors.
The Horse and Massage Therapy 47 What you learn through your fingertips is very important; make sure you remain sensitive to effective aczone 100mg them and what they communicate 100mg aczone visa. Always think of your horse as a very picky discount aczone 100 mg with amex, demanding client who is always checking on you. Contraindications to Massaging a Horse the term contraindication is used to describe specific situations in which you should not massage a horse and in which you should seek the advice of your veterinarian. Do not massage when the horse’s temperature is over 102° Fahrenheit (F) or 39° Celsius (C). An increase in temperature occurs during serious illnesses; feverish conditions call for complete rest. Massage will only ren der the situation worse by increasing blood circulation, which is already rampant. The laying on of hands over the forehead, at the poll, and over the sacrum area will soothe the horse, bringing relief to the cen tral nervous system. During high fever a complete rubdown with a cold towel will decrease the body temperature and cool the animal. When there is an open wound (broken skin) or healing wound (bleeding) anywhere on the body, avoid that particular area, although you may massage the rest of the body to help with excess swelling and to release compensatory tension. When there is acute trauma (a torn muscle or an area with inter nal bleeding, such as an acute hematoma), use ice for the first few hours. When severe forms of functional nervous disease (tetanus) are present, do not massage the horse. Use cold hydrotherapy to numb the nerve endings before and after the lay ing on of hands. During colitis, diarrhea, pregnancy, or hernias, use just a light stroking on the abdomen and only if the horse does not mind. Light massage over the areas affected would relax the compensatory tension from the muscles supporting those structures. Calcification around joints or within soft tissues should not be massaged; it would only increase the inflammation in these areas. An inflammatory condition such as phlebitis would be wors ened by direct massage. Massage is absolutely contraindicated in the following condi tions, since it would contribute to their spread: ❖ Skin problems of fungal origin, such as ringworm ❖ Infectious conditions of fistulous origin, such as poll-evil or fistulous withers ❖ Infectious diseases, such as strangles, tetanus, and pneumonia ❖ Acute stages of viral diseases, such as equine influenza or herpes Be careful when dealing with what appears to be an abnormal situation. When massage is contraindicated, the laying on of hands will often bring soothing energy to an irritated area, reliev ing the pain. Hydrotherapy (chapter 4) will also relieve the inflam mation and pain considerably, assisting recovery and definitively comforting your animal. Knowing how to safely approach an animal for massage is part of the secret to success. Your patience, perseverance, good humor, kindness, knowledge, and skills will reduce the psychological and physical barriers between the horse and you, leading to better communication with the animal. The Horse and Massage Therapy 49 Some Massage Do’s and Don’ts the atmosphere in which you work will directly influence the efficacy of the massage. What follows are some suggestions for making massage treatment safe for both you and your horse. Do’s ✔ Do evaluate the horse’s health by checking his vital signs (pulse, temperature, eyes, breathing, etc. Use the barn aisle or an arena, or work outside if weather permits, preferably in the shade. It is preferable to allow the horse complete freedom of head movement since this promotes better relaxation and permits more feedback signals. This is dangerous if the horse suddenly moves or panics due to outside influences (loud noises, falling objects, storm, etc. Safety Tips When working closely with horses, follow these safety guidelines: ❖ Wear large-size clothes to give yourself freedom of movement. If you only want to warm up your animal with some wringings, shak ings, or tapotements as described in chapter 3, you can wear warm mittens, but it is better to work with bare hands.