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The fetal lung secretes significant quantities of surfactant during late gestation to prepare for initiation of respiration at birth. However, the mechanism by which this occurs has not been determined. Since Ca2+-phosphatidylserine (PS)-dependent protein kinase C has been implicated in surfactant secretion in adult lung, the present study was done to determine whether this enzyme is also involved in the initiation of surfactant release from fetal type II cells. Type II cells isolated from gestational day-24 fetal rabbits were used. Cells were prelabelled with [32P] and [3H]choline and exposed to 4beta phorbol ester (10(-5) M) for 2 h. Secretion product and subcellular fractions were isolated by removing the culture medium, mixing with homogenate from adult rabbit lung, and subfractionating by centrifugation on a sucrose gradient. Samples of secretion product were also prepared for electron microscopy. Ca2+-PS-dependent protein kinase C was also assayed in some samples, and an add-back technique was used to determine whether enzyme activity in the intracellularly stored surfactant fraction was due to contamination. The results showed that material released by fetal type II cells after exposure to phorbol ester coprecipitated with adult rabbit lung lamellar bodies and microsomes. Morphologically, a range of forms, including lamellar-body-like structures, was detected. The released material originated largely from the lamellar body compartment of the fetal type II cells and displayed immunoreactivity with antibody to surfactant protein A (SP-A) at 35 and 70 kDa apparent molecular mass. Assay of protein kinase C in fetal type II cells showed that exposure to conditioned medium, which induces differentiation, increased activity. Incubation with phorbol ester induced translocation of activity to the microsomal fraction. Add-back assays suggested that protein kinase C activation by treatment with phorbol ester induced translocation of enzyme activity to the lamellar body fraction; none was detected prior to treatment. These results support a role for Ca2+-PS-dependent protein kinase C in initiation of surfactant release by interaction with the developing lamellar body compartment in fetal type II cells.

Evidence indicates that Ca +2 -phosphatidylserine-dependent protein kinase C (PKC) is involved in regulation of surfactant secretion. This study was done to examine PKC activity in lung as surfactant synthesis and secretion is initiated, and at birth and to compare these enzyme levels with those in the adult lung. NZW rabbits were used. Fetal and adult lungs were fractionated into subcellular compartments including a lamellar body fraction, which represents intracellular surfactant. The time course for microsomal enzyme activity was compared between 24th gestational day and adult rabbit lung. The reactivity appeared similar in both fractions. PKC specific activity displayed a prominent peak between the 27th and 30th gestational days in total homogenate and lamellar bodies. Specific activity was also high in nuclear, mitochondrial and microsomal fractions the day prior to birth. Adult levels were similar or higher. Total PKC activity was high during late gestation but declined sharply the day prior to birth. A marked increase was present on the first postnatal day. In contrast lamellar bodies displayed a peak in activity between the 27th and 30th gestational days followed by a decline to adult levels. Delipidation of lamellar body fraction indicated that the high enzyme activity in this fraction on the 27th gestational day was not artifactual. The changes observed in PKC in fetal, neonatal and adult lung indicate this enzyme activity changes in lung during the period of onset of surfactant synthesis and secretion during late gestation and may be associated with lamellar bodies, in 27th gestational day fetal lung.

Pulmonary surfactant prevents lung collapse at minimal alveolar diameter. Since surfactant acts extracellularly, secretion is vitally important in regulating the alveolar surfactant levels. Studies with phorbol esters which stimulate protein kinase C (PKC) activity suggest PKC is involved in regulating surfactant secretion. This study was done to characterize PKC activity in adult rabbit lung fractions. Lungs were removed, homogenized and subcellular fractions prepared by centrifugation on a discontinuous sucrose gradient. Calcium-phosphatidylserine-dependent PKC activity was assayed in fractions in the presence of 4 microM phorbol 12-myristate 13-acetate, 1mM EDTA, 8 mole% phosphatidylserine and 1mM Ca2+ by measuring the transfer of 32P from [gamma-32P]ATP to protein. Concurrent assays were done without Ca+2 or PS. Ca+2-PS dependent PKC activity was defined as the difference between the two. Select fractions were incubated with PKC inhibitors sangivamycin, acridine orange or 9-aminoacridine and activity measured. The results showed the majority of the PKC activity was in the cytosolic fraction (87%, specific activity, 142 pmoles/min/mg) but the lamellar bodies also appeared to contain a small amount of PKC activity (approximately 4.0%, 151 pmoles/min/mg). PKC inhibitors were used to examine the characteristics of the enzyme in the microsomal and lamellar body fractions. Sangivamycin was the most potent inhibitor. Some differences in the inhibition characteristics between the lamellar body and microsomal fractions were observed. However using an add-back approach with the lamellar body fraction, indicated that the small quantity of activity in this fraction be attributed to contamination by microsomes. These results indicate that PKC is active in adult rabbit lung subcellular compartments but is probably not associated with the intracellular surfactant storage organelles.

Preliminary studies were carried out on the leaching of copper, zinc, chromium, cadmium and lead from eight kitchen faucets by samples of raw, filtered and distributed Ottawa water, a sample of well water and deionized water containing 2 mg l−1 aqueous fulvic acid. Leaching was effected by allowing the test solutions to stand in the inverted faucets for two successive 24-h periods. Concentrations of the metals found in the leachates were copper: first leaching, 0.12–28.0 mg l−1, second leaching, 0.08-3.54 mg l−1; zinc: first leaching, 0.13-10.25 mg l−1, second leaching, 0.06-2.85 mg l−1; chromium: first leaching

Summary Whole milk powder was reconstituted and the resultant whole milk was passed through a 200-mesh sieve. This treatment removed virtually all the foam or scum from the surface of the milk. The milk was then centrifuged. The insoluble material (foam fraction) which remained on the sieve, and the insoluble material (sediment fraction) which was recovered by centrifugation, were washed with water and freeze-dried. The dried foam fraction contained about 50% more fat than did the sediment fraction. Melting point and iodine value determinations on the ether-extractable portions of the foam and sediment indicated that the fat of the sediment contained a higher proportion of unsaturated fatty acids than did the fat of the foam. Results of electrophoretic analyses of the ether-insoluble portions of the foam and sediment indicated that the major protein constituent of the sediment was beta-lactoglobulin, and that of the foam was casein.

Summary Butter oil was fractionated to obtain products melting at 19–21, 22–24, and 28–30° C. Agglomerated milk powders were prepared, each containing one of these fat fractions, and one powder was prepared containing the unfractionated butter oil. The wettabilities and dispersibilities of the four products were compared with those of commercial whole milk powder and commercial instant skimmilk powder. The results showed that the melting point of the fat in a milk powder affects greatly its wettability and dispersibility. In particular, the milk powder which contained the butterfat fraction melting at 19–21° C. had approximately the same wettability and dispersibility as commercial instant skimmilk powder. The results suggest that control of the physical properties of the fat component of a dried milk powder provides a means of preparing a milk powder with the fat content of whole milk powder and the wettability and dispersibility of a Superior grade of instant skimmilk powder.

Summary Experiments have shown that a spray-dried, agglomerated milk powder containing approximately 25% low-melting (19–21° C.) butter oil fraction, has about the same wettability and dispersibility at 24° C. as a superior grade of instant skimmilk powder. The interfacial tension (oil-water) of this low-melting butter oil fraction was lower than that of higher-melting fractions which yielded much less wettable milk powders. This suggested that the interfacial tension of the fat may play an important role in wettability. Milk powders were prepared from homogenized mixtures of butter oil and condensed skimmilk. In one series of experiments surface active agents were added to the butter oil and in another series they were added to the condensed skimmilk. Wettability measurements on the various milk powders showed that the monoglycerides (Myverol) exerted a more pronounced effect on wettability when they were incorporated in the nonfat portion of the milk, and the Span and Tween preparations exerted a more pronounced effect when they were incorporated in the fat portion of the milk. The results showed that alterations in the interfacial tension of the fat component of a milk powder does not of itself exert a marked effect on wettability.

90 Sr and 137 Cs were determined in the milks of the following mammals: Rocky Mountain bighorn sheep, mountain goat, caribou, husky, beluga whale, fin whale, polar bear and human (Eskimo). The 90 Sr values ranged between 89.8 pCi/g ash for caribou milk to 0.1 pCi/g ash for fin whale milk. The 137 Cs concentrations ranged between 510.9 pCi/g ash for the milk of inland Eskimos to 0.9 pCi/g ash for the milk of mountain goat.

Sixty samples of human milk, 18 of bovine milk, 15 of reindeer milk, 1 of reindeer meat, and different lichens, all collected in Finland, were analyzed for 90 Sr, and 137 Cs. Reindeer milk contained the most 90 Sr, being 119 pCi per liter. Only 5 samples of human milk had detectable amounts of 90 Sr and 4 came from north of Oulu. Human milk from north and south of Oulu contained 114 and 19.7 pCi per liter of 137 Cs whereas bovine milk from the same regions contained 125 and 84 pCi per liter of 137 Cs. Reindeer milk from Lapland contained 1,647 pCi per liter of 137 Cs which is 13 to 14 times more than that of human and bovine milk from the same area. A specimen of dried reindeer meat contained per kilogram, 237 pCi of 90 Sr and 76,124 pCi of 137 Cs. A sample of lichen, Cladonia species, contained 1,361 pCi of 90 Sr and 21,173 pCi of 137 Cs per kilogram.

Strontium-90 and cesium-137 were determined in 40 samples of human milk obtained from 21 different communities in Alaska, as well as in polar bear, dall sheep, and harp seal milk. The average cesium-137 content (pCi per gram of ash) of all samples of human milk collected in Alaska in 1968 was only 3.3% of the average value for all samples of human milk collected in the Northwest Territories in 1967. The average strontium-90 content of the same Alaskan milks was about 10% higher than that of the human milk collected in the Northwest Territories.