Circulation, maternal

Cells containing Hb-F are densely stained with erythrosln and cells with Hb-A appear as ghost cells Intermediate cells are stained more or less pink. Reticulocytes with Hb-A sometimes resemble Intermediate cells and may also show some Intracellular granulation. Inclusion bodies are visible In eluted cells as compact particles of differing sizes. Figure 10 gives some examples. The method Is Ideally suited to demonstrate the presence of newborn red cells In the maternal circulation. The method Is also widely used for the evaluation of the distribution of Hb-F within red cells mainly to differentiate between the HPFH condition and the 3 or 36 thalassemias. Evaluation of F cell smears In such cases Is difficult the term "equal distribution" usually Indicates the presence of Hb-F In each red cell but not necessarily In the same amount. 

Placental transfer of trichloroethylene occurs in animals. Trichloroethylene inhaled by pregnant sheep and goats, at levels used to induce analgesia and anesthesia, is rapidly distributed into the fetal circulation, with peak levels occurring approximately 40-50 minutes after maternal exposure (Helliwell and Hutton 1950). The concentration of trichloroethylene in umbilical vein blood was comparable to that found in the maternal carotid artery. 

Helliwell PJ, Hutton AM. 1950. Trichloroethylene anesthesia. 1. Distribution in the foetal and maternal circulation of pregnant sheep and goats. Anesthesia 5 4-13. 

Hayden LJ, Goeden H, Roth SH. 1990a. Exposure to low levels of hydrogen sulfide elevates circulating glucose in maternal rats. J Toxicol Environ Health 31 45-52. 

Rh incompatibility may occur when an Rh negative mother carries an Rh-positive fetus. At the time of delivery, a small amount of the baby s Rh-positive blood may gain access to the maternal circulation. In response, the immune system of the mother produces anti-Rh antibodies. During the subsequent pregnancy, the fetus is exposed to these antibodies as they cross the placenta. If this fetus is also Rh-positive, then the anti-Rh antibodies attack the fetal erythrocytes and cause hemolytic disease of the newborn (erythroblastosis fetalis). This may occur in about 3% of second Rh-positive babies and about 10% of third Rh-positive babies. The incidence continues to increase with subsequent pregnancies. 

Since transport across the syncytiotrophoblast layer is the rate-limiting step in the absorption of substances from the maternal circulation to the fetal, these cells can provide information on uptake processes which are subject to intracellular regulatory mechanisms or affected by intracellular metabolism. However, it is very difficult to isolate this layer because of its syncytial nature. As a result, the undifferentiated precursor cytotrophoblast cells have been isolated and cultured. These cells do not proliferate in culture, but aggregate and spontaneously differentiate into syncytiotrophoblasts [49],... 

K.E. Schmid, W.S. Davidson, L. Myatt, and L.A. Woollett. Transport of cholesterol across a BeWo cell monolayer Implications for net transport of sterol from maternal to fetal circulation. J Lipid Res. 44 1909-1918 (2003). 

A similar adaptive mutation is found in human fetal hemoglobin. This has a lower oxygen affinity than the adult in the absence of phosphate, but it also has a lower affinity for DPG, due mainly to the replacement His H21(143)/3 — Ser. As a result, the oxygen affinity of fetal blood exceeds that of the adult, which helps the transfer of oxygen from the maternal to the fetal circulation across the placenta (5). 

The rhesus D antigen occurs in 84% of all white individuals, who are therefore Rh-pos-itive. If an Rh-positive child is born to an Rh-negative mother, fetal erythrocytes can enter the mother s circulation during birth and lead to the formation of antibodies (IgG) against the D antigen. This initially has no acute effects on the mother or child. Complications only arise when there is a second pregnancy with an Rh-positive child, as maternal anti-D antibodies cross the placenta to the fetus even before birth and can trigger destruction of the child s Rh-positive erythrocytes [fetal erythroblastosis). 

In areas where malaria is hyper- or holoendemic, newborn infants had high titers of malarial antibody which decreased during the first 6 months of life and then showed a gradual rise throughout childhood until adult levels were attained. The pattern of the malarial fluorescent antibody titer in children in a malaria endemic area, reflected the development of the serum IgG more closely than that of any other immunoglobulins, and the early fall in the titer of the malaria fluorescent antibody coincided with that of the loss of maternal IgG from the children s circulation, implying that malarial antibody is quite capable of traversing the human placenta (M13) (Table 6, Fig. 6). 

In patients with impaired renal function, the serum half-life is prolonged. Pregnancy Category B. Aztreonam crosses the placenta and enters fetal circulation. Lactation Aztreonam is excreted in breast milk in concentrations that are less than 1% of maternal serum. Consider temporary discontinuation of nursing. 

It is well established that most drugs taken by pregnant women are capable of crossing the placenta and reaching the developing fetus. The placenta itself can aid in the protection of the fetus from excessive exposure to drugs in the maternal circulation by... 

D) Secreting drugs from the fetal circulation to the maternal circulation... 

Naloxone is approved for use in neonates to reverse respiratory depression induced by maternal opioid use. In addition, naloxone has been used to improve circulation in patients in shock, an effect related to blockade of endogenous opioids. Other experimental and less well documented uses for naloxone include reversal of coma in alcohol overdose, appetite suppression, and alleviation of dementia from schizophrenia. Side effects of naloxone are minor. 

Dinoprostone is slowly absorbed from the amniotic fluid into the systemic circulation. It and its metabolites readily cross the placenta and can concentrate in the fetal hver. Dinoprostone is primarily metabolized in the maternal lungs and hver and has a half-Ufe in plasma and amniotic fluid of less than 1 minute and 3 to 6 hours, respectively. Carboprost also is metabolized in maternal lung and hver but somewhat more slowly than dinoprostone. It is primarily eliminated by renal excretion of its metabolites, with small amounts appearing in the feces. 

Any implications for the reproductive system arising from an effect on the homeostasis of the major body systems should be considered. For example, compounds that affect the contractility of smooth muscle might be expected to affect the reproductive tract compounds affecting the cardiovascular system might be expected to have an effect in gestation via the maternal circulation or directly on the embryonic cardiovascular system as it develops. 

Oxytocin, a nine amino acid peptide, is synthesized primarily in the paraventricular and supraoptic (SON) nuclei of the hypothalamus, from which it is released to the general circulation through the posterior pituitary (Insel et ah, 1997). However, oxytocinergic fibers have also been found to project from the PVN to the limbic system and several autonomic centers in the brain stem. This central OT pool appears to be independent of pituitary OT release cerebrospinal fluid (CSF) and plasma OT responses to numerous stimuli are not correlated (Insel, 1997). Oxytocin and its analog (or partner) peptide vasopressin are found only in mammals. A related peptide, vasotocin, thought to be the evolutionary precedent of these peptides, is found in reptiles and birds. The first known actions of OT were its peripheral effects on the physiology of new mothers. In mammals, OT stimulates milk ejection and uterine contraction, essential aspects of maternal physiology (Insel et ah, 1997). 

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