Blood flow across the haemochorial placenta was studied by observing classical regional blood pressure, blood flow rate and structure. During pregnancy, fetal tissue provides channels for maternal blood and maternal arteries widen and lengthen.
The uterine arterial system before and placental implantation
Figure 1: Corrosion cast of the uterine arterial system in a virgin mouse and in a near-term mouse (Thesis Th. Kühnel, 2001). Note the dramatic change in arterial diameter and length occurring during pregnancy.
The vascular conductance of the haemochorial placenta was found to be several times the overall uteroplacental conductance, indicating, that the supplying arteries control placental blood flow. When shear rate in the supplying arteries were increased by experimental manipulation, arterial dilatation rises compensatory, indicating that blood flow regulation proceeds by sensing shear rate.
Concept of placental blood flow control
Figure 2: Model for placental blood flow control. Fetal tissue builds a highly conductive stream bed for maternal blood causing rise of shear rate on the endothelium of the supplying arteries. Shear rate causes widening and lengthening of the arteries via growth factors such as monocyte chemo - attracting proteins. This way, the fetus takes over maternal blood flow control in accordance to its needs.
For further information see also:
Structure adaptation and blood flow control in the uterine arterial system after hemochorial placentation.
Eur J Obstet Gynecol Reprod Biol. 2003 Sep 22;110 Suppl 1:S19-27.
Besides finishing previous studies, I used the freedom provided by emeritation to devote myself, by theoretical studies, to additional problems beside my special topics.
Stoichiometry shows that ATP synthesis is associated to net OH- release, ATP break-down to OH- uptake. From this it may be concluded that OH- circulates between the mitochondria and the ATPase systems.
Intracellular OH- circulation
Figure 3: Circulation of OH- between ATP-Synthase and ATPase. ATP synthase produces ATP (2-PO3 - RA) and OH-, which is delivered to creatine kinase, where creatine phosphate (2-PO3-RC) and water (H+-OH-)is formed, which, in the creatine kinase close to the ATPase, is transformed back to ATP and OH- to be taken up by the ATPase. ADP (RA-1) and anorganic phosphate (2-PO3-OH-), i.e. OH- in dissociated, bound form, is produced by the ATPase and delivered , via the creatine kinase, to the ATP synthase.
It is shown by theoretical analysis, that OH- ions are transported by facilitated diffusion predominantly bound to CO2 as hydrogen carbonate ions. Diffusion and rotation of proteins contribute to intracellular OH- transport.
Wissenschaftliche Verantwortung und gesetzliche Vorgaben (Tierschutzgesetz, Tierschg §9,2) zwingen, bei Tierversuchsvorhaben die minimale,
ausreichende Anzahl an Tieren zu verwenden. In dem amtlichen Antragsformular auf Genehmigung eines Tierversuchsvorhabens (§188.8.131.52.)
muss die Biometrie (Bestimmung) der notwendigen Anzahl vorgelegt werden. Die Biometrie soll mit folgenden Kenngrößen erfolgen: (1) der biologisch
gerade noch relevanten Gruppen-Differenz der Messgröße (Zielgröße), (2) der aus früheren Messungen abzuleitenden Standardabweichung (Variabilität)
der geplanten Messungen, sowie (3) der akzeptierten Irrtum -Wahrscheinlichkeit des Fehlers erster und zweiter Art. Der vorliegende Aufsatz ist eine
Anleitung zu der geforderten Biometrie der minimalen ausreichenden Anzahl der Tiere bei Gruppenvergleichen und Korrelationsstudien. Hierbei wird zur
Biometrie zunächst die allein mit Plausibilitätsgründen mögliche Festlegung der dimensionslosen variabilitätsbezogenen relevante Gruppen- Differenz
(relevante Differenz / Standardabweichung) empfohlen ( z. B. Festlegung auf 1.5). Festgelegt werden weiter die Irrtum - Wahrscheinlichkeit erster
und zweiter Art (empfohlen 0.05 und 0.20-power =80). Mit der so festgelegten variabilitätsbezogenen relevanten Differenz und Irrtum -
Wahrscheinlichkeit sowie der Zahl der geplanter Gruppenvergleiche wird die minimale ausreichende Gruppengröße mit Hilfe einer mit EXCEL lösbaren
Gleichung oder mit Hilfe beiliegender Diagramme bestimmt.
Mitochondria and technical fuel cells are similar in principle; they both transform chemical energy for oxygen and hydrogen and hydrogen delivering material into electrical energy. I compared the two systems with respect to circuitry, voltage output and current output. It turns out that the mitochondria imply two circuits, the technical fuel cells one.
Mitochondrion vs. technical fuel cell
Figure 4: Mitochondrial fuel cell vs. technical fuel cells. In both systems, electron current (yellow) and ionic current occur in series. In the mitochondria, this electron current is transformed into an output current, where voltage is down regulated and current is up regulated. In the technical fuel cell, in contrast, the electron current is directly applied to the motor.
The mitochondria are low voltage - high current systems; the technical fuel cells are high voltage - low current systems. The energy output per weight, varying in the different models of technical fuel cells, is in the same range for mitochondria and technical fuel cells.
Since Einstein (1905) it is generally believed that physiological processes, as all physical and chemical processes, slow down in an aircraft when it speeds up to velocities near speed of light. This slow down is called time dilatation or the relativistic clock paradox. For a speed of 99.5% of speed of life, the physiological processes should have a velocity of around 1/10 that a rest. Interesting enough, the organism should tolerate these changes since slow-down of respiratory and circulatory functions are correlated by analog changes in metabolic rate, i.e. oxygen need. Muscle force cannot bear the weight at earth; this, however, is irrelevant since the space craft is normally in the state of weightlessness. On the other hand, the physical basis of the clock paradox appears weak if not absent. In one single experiment, atomic clocks were observed during a around the word trip. When compared to atomic clocks resting on earth they were 59 ns late after an eastward trip and 275 ns fast after a westward trip while the same delay was expected on the basis of the special relativity theory. The special relativity theory is based on the assumption that speed of life is constant in vacuo and independent upon the speed of the light source. This assumption, however, has never been proved. There is no measurement of the speed of light in true vacuum; in all measurements of speed of light, the observed light has, before the measurement, passed thousands of atoms, where the speed is adjusted to that of the atoms. Thus, a slow-down of life in a space - craft with near - light speed, the clock paradox, seem to be roughly compatible with physiology but there is no physical evidence for it.