Simultaneous measurement of acetylcholine and choline in brain by pyrolysis-gas chromatography-mass spectrometry

Pyrolysis-gas chromatography and chemical ionization mass fragmentography were combined to develop a specific, simple and rapid method for simultaneously measuring endogenous and stable isotopic variants of acetylcholine and choline with a detection limit of approximately 10(-12) mol. The recovery and reproducibility of the method are excellent, and the method is suitable for measuring acetylcholine and choline in discrete regions of rat brain and to measure incorporation of choline into acetylcholine, both of which uses are demonstrated. This method affords easy analysis of 40 samples in a working day. The new technique used to extract compounds from tissues and the modified gas flow arrangement may be useful to measure other compounds as well.     

Preparation of cryoprecipitated factor VIII concentrates

Factors affecting the yield of factor VIII in cryoprecipitate have been investigated in the context of a blood component program. Both in vitro and in vivo measurements were used to assess the effects of critical variables on the yield of factor VIII activity. Variables such as anticoagulant, plastic bag, mixing during collection, and platelet contamination had no significant effect on yield of factor VIII activity in cryoprecipitate. Among the most critical factors affecting yield were storage time of whole blood and procedures for freezing, thawing, and reconstitution. The following procedures were found to assure a 60 per cent recovery of factor VIII in cryoprecipitate: 1)processing of whole blood within six hours of collection; 2)use of a technique to freeze plasma within 30 minutes either in a -70 C ethanol bath or -85 C freezer; 3)rapid thawing (1 1/2 hour or less) in a 4 C circulating water bath; 4)centrifugation at 4,500 X g for 10 minutes at 4 C followed by draining of the supernatant in a 4 C cold room; 5) storage of the precipitate at -20 C until ready for use; 6) thawing in a 37 C water bath for at least 15 minutes followed by addition of 20 ml of 0.15 M saline for a 20 minute period at room temperature, and gentle mixing before pooling units for transfusion. The recovery of factor VIII in cryoprecipitate appears to be limited to about 65 per cent by its solubility in plasma at 4 C. Therefore, further effort to increase the amount available for treatment should involve improving the supply of plasma for its preparation and decreasing the cost of processing.     

Letter: Risks and benefits of hormonal agents in pregnancy

Concern over the possible teratogenic effects of the hormone 17alpha -hydroxyprogesterone caproate (17alpha OHP-C) when given intrapartum to the mother and the possible effects on the cervix and vagina in later life, was voiced in response to a published report, and advocacy of use of this hormone for the prevention of early abortion questioned. In response, the authors share their concern over possible long-term carcinogenic effects as well as possible effects on the hypothalamic-pituitary-gonadal axis, the mammary apparatus, the male genitalia, and psychosexual behavior.     

Disability: a model and measurement technique

As a result of histological and ultracytochemical investigations concerning the influence of thiamine and its disulfide derivative, thiamine tetrahydrofurfuryl disulfide (TTFD), on acetylcholinesterase (AChE) in extirpated guinea pig atria, it was found that there was a clear increase in the AChE activity by 10(-4) M TTFD, a weak increase with 10(-5) M and an extremely weak increase, about the same as that in only the nutrient (Locke's solution), with 5 x 10(-4) M. However, with 10(-4) M of thiamine there was a tendency for the activity to be the same degree as with Lock's solution alone or be even inhibited at times.