Search

Safely-injectable suspensions of human serum [methyl-11 C] methylalbumin microspheres have been prepared via the reaction of human serum albumin microspheres with [11C]methyl iodide, itself prepared in a novel one-pot synthesis from cyclotron-produced [11C]carbon dioxide. The preparation takes only 30 min from the end of radionuclide production and proceeds in 22% radiochemical yield based on the activity of [11C]carbon dioxide used and decay-corrected. It has been shown that such microspheres are highly stable in vivo and may be used as reference blood flow markers in positron emission tomography (PET). Similarly, safely-injectable and radiochemically pure solutions of human serum [methyl-11C] methylalbumin have been prepared in 31% radiochemical yield and in 40 min from the end of [11C]carbon dioxide production via the reaction of [11C]methyl iodide with human serum albumin. This radiopharmaceutical is intended for studies of lung permeability and blood-brain barrier permeability by PET.

[N-methyl-11C]Sertraline, a potential agent for the study of the serotonergic system in vivo with positron emission tomography, was prepared by N-methylation of the corresponding norcompound with [11C]iodomethane, which was itself prepared from cyclotron-produced [11C]carbon dioxide. Under the best conditions found [norsertraline free base (20 mM) in DMF (0.70 mL), 120 degrees C for 8 min] [N-methyl-11C]-sertraline can be prepared in 43% radiochemical yield from [11C]iodomethane (decay-corrected), corresponding to 20% overall radiochemical yield from [11C]carbon dioxide (decay-corrected), with high specific radioactivity. Preparations can be ready for i.v. injection 50 min from the end of radionuclide production.

Based upon two recent periods of fieldwork among a spontaneously resettled population of cattle herders in southwestern Ethiopia, this paper is an attempt to illustrate, by a particular case, the general proposition that external aid, if it is not to be counter-productive, must meet people's needs as they themselves define them. The people in question, the Mursi, have experienced, since 1970, their worst period of drought and hunger in living memory. They have responded to this experience with resilience and inventiveness and largely without external assistance. The paper concentrates on a recent, drought induced, migration of Mursi to higher land, outside their traditional territory, and shows how the migrants are adapting to a new way of life which brings them into direct conflict with some of their most cherished cultural traditions.

A method is described for measuring the regional cerebral-to-large vessel haematocrit ratio using inhalation of carbon-11-labelled carbon monoxide and the intravenous injection of carbon-11-labelled methyl-albumin in combination with positron emission tomography. The mean value in a series of nine subjects was 0.69. This is approximately 20% lower than the value of 0.85 previously reported. It is concluded that previous measurements of regional cerebral blood volume using a haematocrit ratio of 0.85 will have underestimated the value of regional cerebral blood volume by 20%.

Regional cerebral blood flow (rCBF) values were measured in nine normotensive subjects with known previous myocardial infarctions using 15 mu 11C-methylalbumin microspheres and positron emission tomography (PET). Microspheres were injected directly into the left ventricle of each subject during routine cardiac angiography and blood flow calibrated using the reference sample technique. rCBF values were compared with those obtained for a group of fifteen age-matched normal controls using the C15O2 steady-state inhalation technique. Using 1 cm radius circular regions of interest, the 11C-microspheres approach yielded mean blood flow values of 51 ml/100 ml/min and 48 ml/100 ml/min for regions of interest dominated by temporal and frontal cortical grey matter respectively. An rCBF value of 32 ml/100 ml/min was obtained for regions of interest dominated by frontal white matter. Mean rCBF values obtained for these regions using the C15O2 method were not significantly different (52 ml/100 ml/min, 44 ml/100 ml/min, and 28 ml/100 ml/min respectively), but the C15O2 approach gave a significantly lower rCBF value than the 11C-microspheresfor regions of interest dominated by occipital grey matter. Although the two groups of subjects studied were not strictly equivalent, the good agreement between blood flow values obtained using the 11C-microspheres and the C15O2 techniques is of interest, and suggests that the assumptions of the C15O2 steady-state approach do not lead to large errors in practice.

A mixture of 14 polychlorinated biphenyl (PCB) isomers of various congeners, representing approximately 70% of all human milk PCBs reported in the literature, was made up to identify and approximate their residues in human milk. Individual isomer levels varied from 5 to 103 nanograms per gram of milkfat with the 2,2',4,4',5,5'-hexachlorobiphenyl isomer as the major PCB contaminant of human milk. PCB isomer numbers 74, 118, 153, 138 and 180 made up approximately 75% of all PCBs as measured by this mixture. There was close agreement of total PCB isomer content in breast milk between electron capture gas chromatography and gas chromatographic mass spectrometry determinations. A major interference was encountered however for PCB isomer no. 52, whose residue level in the breast milk was approximately 3 X higher by gas liquid chromatography than by mass spectrometry.

Regional cerebral haematocrit has been measured in seven patients with brain tumours, and in one normal subject, using positron emission tomography (PET). Red cell and plasma volumes of distribution were assessed using 11CO and [methyl-11C]albumin, respectively. Haematocrit values were compared with values of regional cerebral blood flow (rCBF) measured using steady-state inhalation of C15O2. Only two of the seven cerebral tumours studied showed any increase in uptake of [methyl-11C]albumin over 45 min. Values of r, the regional ratio of cerebral small-to-large vessel haematocrit, varied from 0.52 to 0.84 for the seven tumours studied. No correlation between r and tumour blood flow was observed. The normal subject yielded an r value of 0.69 for the mean whole brain small-to-large vessel haematocrit ratio. No significant difference between gray and white matter r values was found. The contralateral hemispheres of the seven tumour patients studied yielded an overall mean r value of 0.71 +/- 0.05. We conclude that it is reasonable to assume an r value of 0.7 in tomographic calculations of regional cerebral blood volume (rCBV) from red cell or plasma volumes of distribution in normal brain. Such an assumption for tumours, however, may lead to errors of 35% in estimated rCBV.

A total of 210 breast milk samples from 5 different regions across Canada were analyzed for polychlorinated biphenyls (PCBs), hexachloro-1,3-butadiene, ten chlorinated benzenes, two chlorinated naphthalenes, Mirex, photomirex, alpha, beta and gamma hexachlorocyclohexane, alpha and gamma chlordane, oxychlordane, trans-nonachlor, p,p'-DDT and some analogs, heptachlor epoxide, dieldrin and octachlorostyrene. There was no evidence for the presence of hexachloro-1,3-butadiene, Mirex, octachlorostyrene, chlorinated naphthalenes or tetrachlorobenzenes in the breast milk. Residues of other compounds were found in all samples, except 1,2-dichlorobenzene, gamma hexachlorocyclohexane, alpha and gamma chlordane and p,p'-TDE, which were less frequently observed, while o,p'-DDT was only found in approximately one quarter of all samples. Since 1967, a steady decline in heptachlor epoxide, dieldrin and p,p'-DDT and related residues is apparent. At the same time however, there is an apparent increase in PCB residue levels since 1970. This apparent increase should be viewed with some caution, since much of this increase might be attributed to better sampling and analytical techniques. Residue levels of breast milk in Canada were similar to those found in other industrial nations. Regional differences in residue levels appeared to be minimal.

A total of 29 human adipose tissue samples from autopsies of nonaccidental death victims from across Canada were analyzed for polychlorinated biphenyls and organochlorine pesticides. The residue levels of nonaccidental death victims were compared to those obtained earlier for samples of accidental death victims, collected during the same time period. A statistically significant difference was observed for hexachloro-1,3-butadiene (P less than 0.005) between the two sampling procedures. No statistically significant differences were found for other residues, although residue levels of hexachlorobenzene and p,p'-DDE were numerically higher in nonaccident than accident victims. Samples of nonaccidental deaths were subdivided into "sudden" and "other" death groups. Residue levels according to sex were statistically not related to the cause of death, although numerically the average p,p'-DDE level in male adipose tissue was higher in the "other" than "sudden" death group. The average p,p'-DDT levels in female adipose tissue of nonaccident victims were numerically at least twice those of accident victims, but were not statistically different.