Donkin psychosis may not be rare: a British series included 13 possible cases; but clarifying its distinction from postpartum bipolar disorder requires prospective investigations in collaboration with obstetricians. Wernicke-Korsakoff psychosis
This was described by Wernicke and Korsakoff. The pathology is damage to the core of the brain including the thalamus and mamillary bodies. Its most striking clinical feature is loss of memory, which can be permanent. It is usually found in severe alcoholics, but can also result from pernicious vomiting of pregnancy (hyperemesis gravidarum), because the requirement for thiamine is much increased in pregnancy; nearly 200 cases have been reported. The cause is vitamin B1 (thiamine) deficiency. This has been available for treatment and prevention since 1936, so the occurrence of this syndrome in pregnancy should be extinct. But these cases continue to be reported – more than 50 in this century – from all over the world, including some from countries with advanced medical services; most are due to rehydration without vitamin supplements. A pregnant woman who presents in a dehydrated state due to pernicious vomiting urgently needs thiamine, as well as intravenous fluids. Vascular disorders
Various vascular disorders occasionally cause psychosis, especially cerebral venous thrombosis. Puerperal women are liable to thrombosis, especially thrombophlebitis of the leg and pelvic veins; aseptic thrombi can also form in the dural venous sinuses and the cerebral veins draining into them. Most patients present with headache, vomiting, seizures and focal signs such as hemiplegia or dysphasia, but a minority of cases have a psychiatric presentation.
Acid–base homeostasis is the homeostatic regulation of the pH of the bodys extracellular fluid (ECF). The proper balance between the acids and bases (i.e. the pH) in the ECF is crucial for the normal physiology of the body—and for cellular metabolism. The pH of the intracellular fluid and the extracellular fluid need to be maintained at a constant level.The three dimensional structures of many extracellular proteins, such as the plasma proteins and membrane proteins of the bodys cells, are very sensitive to the extracellular pH. Stringent mechanisms therefore exist to maintain the pH within very narrow limits. Outside the acceptable range of pH, proteins are denatured (i.e. their 3D structure is disrupted), causing enzymes and ion channels (among others) to malfunction. An acid–base imbalance is known as acidemia when the pH is acidic, or alkalemia when the pH is alkaline. Lines of defense
In humans and many other animals, acid–base homeostasis is maintained by multiple mechanisms involved in three lines of defense:
Chemical: The first lines of defense are immediate, consisting of the various chemical buffers which minimize pH changes that would otherwise occur in their absence. These buffers include the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system. Respiratory component: The second line of defense is rapid consisting of the control the carbonic acid (H2CO3) concentration in the ECF by changing the rate and depth of breathing by hyperventilation or hypoventilation. This blows off or retains carbon dioxide (and thus carbonic acid) in the blood plasma as required.