The effects of vitamin E deficiency on the total fatty acids and the phospholipid fatty acids of rat tissues

1. A vitamin E-low diet containing 7% stripped lard was given to hooded rats for periods up to 14 months. Control rats were given the same diet with a vitamin E supplement (I i.u./rat per day).

2. No consistent pattern of changes was found in the total fatty acids of testis, lung, spleen, pancreas, heart, kidney, liver, brain, skeletal muscle and small intestine from rats given the deficient diet for 5, 6 or 7 months when compared with control rats.

3. The fatty acids of the total phospholipid from the same tissues were examined after 4, 5, 8 or 14 months. In the rats deficient in vitamin E the polyunsaturated fatty acids of the linoleic series (ω6) decreased, except for 20:4ω6, which in some tissues tended to increase. After 14 months there were considerable decreases in the percentages of all theω6 series including 20:4ω6 with increases in the percentages of 18:1ω9 and 20:3ω9 the pattern was similar to that found in essential fatty acid deficiency.

Pancreatic insulin content of nonpregnant, pregnant and postpartum rats and the developing rat fetus

A study was made of the insulin content of pancreases of nonpregnant, pregnant and postpartum rats and of their developing fetuses. The insulin content of the extracts was measured by radioimmunoassay, using crystalline rat insulin as a standard. The mean concentration of insulin in the pancreas of nonpregnant animals was 43 ± 6 μg./gm. The insulin concentration did not change significantly during late pregnancy or on day 4 postpartum. However, the weight of the pancreas was significantly greater in the pregnant and the postpartum rats. Thus, the total insulin content of the pancreas was greater in the pregnant and postpartum rats, being 23 ± 1.4 μg. and 24 ± 1.9 ng. respectively, as compared to 15 ± 0.7 μg. in the nonpregnant rats.

The fetal pancreases were obtained at five periods of gestation: daily from day 18 to day 22, and on day 4 after birth. The mean weight of the fetal pancreases progressively and significantly increased from 4.4 ± 0.3 mg. on day 18 to 14.1 ± 1.5 mg. on day 20. On day 4 after birth, the mean pancreatic weight was 15.1 ± 0.5 mg. The fetal pancreatic insulin concentration rapidly and progressively increased from 14 ± 2 μg./gm. on day 18, to 80 ± 9 μg./gm. on day 21, and by day 4 after birth was 621 ± 103 μg./gm. By day 21 the fetal pancreatic insulin concentration had reached the prenatal peak and was already twice that of the mother. The total fetal pancreatic insulin content showed a progressive increase during the fetal life from 0.07 ± 0.01 μg. on day 18, to 1.23 μg. on day 21, a seventeen fold increase.

The effect of a high-carbohydrate diet on glucose, insulin sensitivity and plasma insulin in rats

When groups of rats were kept on control and high-carbohydrate diets from the end of lactation until their body weight reached 150 g. it was found that the animals fed on the high-carbohydrate diet gained weight more rapidly, with an increase in fat deposits.

Glucose and plasma insulin in both groups were compared with the amounts of hormone extracted from their pancreases. When the rats on the control diet were killed the insulin and glucose plasma levels were 40 ± 3 μu./ml. and 156·69 ± 13 mg./100 ml. respectively. After 17–20 hr. fasting these values decreased significantly (P < 0·01) to 18 ± 1·5 μu./ml. and 116 ± 13 mg./ml. The amount of insulin in the pancreas was not modified by fasting. In the rats fed on the high-carbohydrate diet the plasma insulin and glucose values were higher than those in the control rats (50 ± 3·8 μu./ml. and 187 ± 19 mg./100 ml.); after 17–20 hr. starvation the glucose levels were reduced and the plasma insulin concentration remained higher (44 ± 2·9 μu./ml.); the insulin content of the pancreas was higher than in the control rats. In vitro the epididymal fat and the diaphragm of the rats on the high-carbohydrate diet were less sensitive to insulin than the same tissues in the controls.

Preparation and partial characterization of crystalline human insulin

Crystalline human insulin was prepared from human pancreas glands in relatively large amounts employing acid-ethanol extraction, fractional precipitation with salts and organic solvents, gel filtration, and crystallization from ammonium acetate buffer. The crystalline insulin had a potency of about 25 International Units per milligram. Polyacrylamide gel electrophoresis showed that the material consisted of a major component and several minor components similar to those usually observed in insulins derived from other species. Amino acid analyses of the crystalline material were consistent with the structure proposed for human insulin by Nicol and Smith.

Failure of guinea pig antibodies to beef insulin, chicken insulin, and cod insulin to neutralize capybara insulin

Guinea pig and coypu insulins are the only mammalian insulins known to be non-neutralizable by antibody to beef insulin. A third non-neutralizable mammalian insulin, that of the capybara (carpincho, or hydrochoerus hydrochoerus) has been identified. Capybara pancreas yielded 0.5 U. extractable insulin per gram. An amount of guinea pig antibody to beef insulin sufficient to neutralize thirty times as much beef insulin did not significantly alter the increase in glycogen content produced by pancreatic capybara insulin in the mouse hemidiaphragm in vitro. Both 50 mU. capybara insulin and 50 mil capybara insulin plus 150 mU. antibody to beef insulin when injected into mice produced about the same number of convulsions and lowered the blood glucose to about the same mean level as did 50 raU. beef insulin alone. Mice injected with 50 mU. beef insulin plus 150 mU. antibody to beef insulin did not convulse and had a mean blood glucose of 156 mg. per 100 ml. Antibody to chicken insulin and antibody to cod insulin did not significantly alter the increase in glycogen content produced by pancreatic capybara insulin in the mouse hemidiaphragm in vitro.

Capybara pancreatic extract cross-reacted with guinea pig antiserum to beef insulin in the passive cutaneous ana-phylaxis test.

Human crystalline insulin from non-diabetic and diabetic patients

Crystalline insulin was prepared from pooled pancreases from deceased maturity onset diabetics and non-diabetics. A comparison was made of the amino acid composition, immunological reactivity and hypoglycaemic activity. No differences could be demonstrated between the two preparations.

Pancreatic B cell morphology and insulin content of normal and alloxan-diabetic rabbits and their offspring

The pancreases of eight normoglycemic and of nine alloxan-diabetic rabbits, and those of their respective litters, sacrificed within one week after birth, were studied by light and electron microscopy and were assayed for insulin by the double-antibody method. The insulin concentrations of the pancreases from the neonatal rabbits averaged 0.56 U. per gram of wet tissue in rabbits born to normoglycemic mothers and 0.73 U. in those born to alloxan-diabetic animals. Since ultrastructurally in the neonatal rabbits of both groups mostly paid B cell granules were encountered, it is concluded that pale granules contain assayable insulin. This agrees with previous immunofluorescent studies, in which it was also shown that the pale granules contain insulin. The relatively lower number of B cell granules as well as the more prominent display of vesicular units of the endoplasmic reticulum in rabbits born to alloxan-diabetic animals suggest that a state of hyperfunction, induced by hyperglyceinia transmitted through the placenta by the mother rabbit, exists in the B cells of this group of neoaates. On the other hand, the absence of blood sugar changes in the diabetic mother animals during pregnancy is in keeping with former observations that insulin fails to cross the placental barrier in rabbits (and other mammals).

Detection of complex carbohydrates in the Golgi apparatus of rat cells

Two methods used for the electron microscopic detection of glycoproteins were applied to a variety of cell types in the rat; one involved successive treatment of sections with periodic acid, chromic acid, and silver methenamine; and the other, a brief treatment with a chromic acid-phosphotungstic acid mixture. The results obtained with the two methods were identical and, whenever the comparison was possible, similar to those obtained with the periodic acid-Schiff technique of light microscopy. In secretory as well as in nonsecretory cells, parts of the Golgi apparatus are stained. The last saccule on one side of each Golgi stack is strongly reactive (mature face), and the last saccule on the other side shows little or no reactivity (immature face); a gradient of reactivity occurs in between these saccules. The more likely explanation of the increase in staining intensity is that carbohydrate is synthesized and accumulates in saccules as they migrate toward the mature face. In many secretory cells, the mature face is associated with strongly stained secretory granules. Other structures stained are: (1) small vesicles, dense and multivesicular bodies, at least some of which are presumed to be lysosomal in nature; (2) cell coat; and (3) basement membrane. The evidence suggests that the Golgi saccules provide glycoproteins not only for secretion, but also for the needs of the lysosomal system as well as for incorporation into the cell coat and perhaps basement membrane.

The human secretory immunoglobulin system: immunohistoligical localization of gamma A, secretory "piece," and lactoferrin in normal human tissues

The immunohistological localization of gammaA, secretory "piece" (SP), and lactoferrin (LF) in the mucosae of a variety of normal human tissues was investigated using specific fluoresceinated antisera. gammaA staining was localized in the apical portion of the mucosal epithelium, intercellular spaces, basement membrane area, and plasma cells of the interstitium or lamina propria of a number of normal human tissues. SP was ubiquitous in the mucosal epithelium of all tissues studied which included parotid and submaxillary glands, bronchi, pancreas, GI tract, sweat glands, kidney, and gall bladder. In addition, SP staining was localized in the intercellular spaces and on the surface of the epithelial cells lining the lumen of the secretory glands. No SP staining was observed in the plasma cells of the interstitium or lamina propria surrounding the secretory glands in these tissues, and no SP staining was observed in sections of normal spleen or lymph node tissue. SP staining was observed in the sweat glands, pancreas, and kidney in the absence of gammaA staining. LF was much less ubiquitous in the epithelial cells of the various tissues studied and appeared to be restricted primarily to the acinar epithelium of the bronchial mucosae, parotid, and submaxillary salivary glands, and was also found in renal tubular cells. A hypothetical model for the transport of gammaA and SP across mucosal membrane epithelium is presented.