MICRURGICAL STUDIES IN CELL PHYSIOLOGY : VI. CALCIUM IONS IN LIVING PROTOPLASM.

The quiescence, rounding, sinking of the granules, and paling of the nucleus are similar to the effects seen after the injection of potassium and sodium chloride (11). Since the sodium salts of the anions were used, it might be inferred that the sodium is the active agent in the injected solutions. This is not entirely the case, however, for the effective concentrations of NaCl required are many times greater than those required in the case of the sodium salts of the calcium-precipitating anions. The fact that practically the same effects can be obtained in both cases leads one to suspect that there is a relation between the results of an increase in sodium ions and a decrease in calcium ions. It has been shown that a M/416 CaCl₂ solution will antagonize a M/1 NaCl solution and even a more concentrated solution of KCl inside the ameba (12). Therefore the reduction in amount of calcium may leave a comparatively high concentration of unantagonized sodium and potassium. The fine, purplish red granules resulting from the injection of the alizarin are, no doubt, the insoluble calcium alizarinate. Recovery of an ameba from such an injection may be explained by the postulate that the free calcium ions in the living ameba are in equilibrium with a reserve supply of unionized calcium. The equilibrium is upset when the free calcium is removed by precipitation or by other means, and the system may possibly react in such a way as to counteract the effect of the change imposed. By mobilization of the calcium from a reserve supply the ameba can therefore gradually resume its normal activity. The time required for the recovery depends on the amount of alizarin injected. The diffuse red color which is seen immediately following the injection of alizarin probably represents that extra amount of dye which was not used in precipitating the immediately available calcium. Then, as the calcium is being liberated from the reserve, it is taken up by this surplus alizarin, resulting in a gradual loss of the diffuse coloration and an increase in the number of purplish See PDF for Structure red calcium alizarinate granules. Only when all of the injected dye has been precipitated can the mobilized calcium be used to carry on the normal physiological processes of the organism. The need of calcium to effect ameboid movement has been shown by Pantin (13) in a series of immersion experiments. This fact is quite suggestive, because the first effect of the injection of any of the calcium precipitants is absolute quiescence. Furthermore, there is no return to normal movement until the calcium apparently becomes available to the protoplasm. In support of the conception of a reserve supply of calcium is the presence of the large crystals which give a positive reaction with alizarin for calcium on the death of the ameba. Schewiakoff (14), from crystallographic studies, claims that they are calcium phosphate. The effect of the injection of the calcium-precipitating anions on the calcium of the protoplasm may be shown in another way. In determining the relative toxicity of these salts an arbitrarily standardized injection, about one-fourth of the volume of an ameba, was used. This was introduced because of the necessity to avoid effects due to variable amounts of the solvent, viz., water.. Thus the water effect was kept constant, and the variations in actual amount of salt injected were obtained by using a graded series of concentrations. Arranging the sodium salts of these anions in order of increasing toxicity in one column, and the in vitro solubility products of the corresponding calcium salts in another column, it is seen that as the toxicity increases, the solubility product decreases (Table 1). This fact strongly suggests that the toxicity depends on the ability of the salt to remove calcium ions from the protoplasm. The apparent deviation of the carbonate from the rule can be explained by the specific effect of 002 (10) which is always present from the hydrolysis of the carbonate.     

Actin-containing cables within anchorage-dependent rat embryo cells are dissociated by plasmin and trypsin

The distribution of intracellular actin has been examined by specific immunofluorescence in a series of normal and SV40-transformed cell lines of rat origin. A consistent correlation was found between the presence of large thick sheathes of actin-containing material and anchorage-dependent growth control. Anchorage-independent growth by these cells has been shown to be associated with the production and secretion of a plasminogen activator, and dependent upon the presence of the active protease plasmin. We have found that these phenomena can be linked as follows. First, treatment with plasmin, but not urokinase or plasminogen, reversibly removes the actin-containing cables from normal rat embryo fibroblasts, and similar results are obtained with trypsin. Thrombin and chymotrypsin are relatively ineffective in causing the disappearance of the cables. Second, sera such as dog or monkey, which permit high levels of plasmin formation and activity, support cell growth in semi-solid media better than sera in which plasminogen is activated poorly or that are plasminogen-deficient; concomitantly, cables disappear in the former but not in the latter sera. The addition of a plasmin inhibitor prevents the disappearance of actin-containing cables.     

Carbon dioxide induces endotrophic germ tube formation in Candida albicans

Candida albicans formed germ tubes when exposed to air containing 5 to 15% carbon dioxide (CO2). The CO2-mediated germ tube formation occurred optimally at 37 degrees C in a pH range of 5.5 to 6.5. No germ tubes were produced at 25 degrees C, even when the optimal concentration of CO2 (10%) was present in the environment. The requirement of CO2 for germ tube formation could be partially substituted by sodium bicarbonate but not by N2. Carbon dioxide was required to be present throughout the entire course of germ tube emergence suggesting that its role is not limited to an initial triggering of morphogenic change. We suggest that carbon dioxide may be a common effector responsible for the germ tube promoting activity of certain chemical inducers for C. albicans.     

The requirements for bicarbonate and metabolism of the inducer during germ tube formation by Candida albicans

Factors affecting germ tube formation in Candida albicans at suboptimal temperatures were investigated. Candida albicans formed germ tubes between 22 and 30 degrees C in solution when incubated without shaking, in the presence of bicarbonate (2 mg mL-1). Other conditions depended on the inducer used. Proline could induce germ tube formation optimally only when its concentration was between 200 and 400 mM. A concentration of 0.05 mM N-acetylglucosamine was sufficient to induce germ tube formation. N-Acetylglucosamine could induce germ tube formation at 30 but not at 25 degrees C. N-Acetylglucosamine induced germ tube formation was most reproducible when the cells were first starved by incubation in water for 16-24 h at 20 degrees C. Germ tubes induced by proline could be formed at pH values between 3.8 and 9.0 at 30 degrees C, but only between 7.0 and 7.5 at 25 degrees C. The addition of 0.05 to 5 mM glucose to a 5 mM proline induction solution allowed germ tube formation at 30 but not at 25 degrees C. Glucose (400 mM) did not suppress germ tube formation at 30 degrees C but only 5 mM was sufficient to cause a 65% suppression at 25 degrees C. The results show the importance of CO2 and (or) bicarbonate to the induction of germ tube formation and are consistent with the metabolism of the inducer.     

Cholestatic jaundice caused by cloxacillin: macrophage inhibition factor test in preventing rechallenge with hepatotoxic drugs.

Severe intrahepatic cholestasis occurred in a patient after taking nitrofurantoin, ampicillin, and cloxacillin. As only nitrofurantoin was known to cause cholestasis she was given cloxacillin again two years later. The cholestasis reappeared at once. A macrophage inhibition factor test confirmed that cloxacillin was the offending drug. Cloxacillin should be added to the growing list of drugs causing cholestasis. Inadvertent rechallenge with hepatototoxic drugs might be prevented by routine use of the macrophage inhibition factor test.     

Immature red cells have ferritin receptors

Ferritin binds to immature red cells. The binding appears to be specific: (1) It is abolished by a large competing dose of nonradioactive ferritin. (2) There is little binding of ferritin to mature red cells. (3) Other high molecular weight proteins (gamma globulin and thyroglobulin) are not bound.     

Life Years Lost Associated with Obesity-Related Diseases for U.S. Non-Smoking Adults

The objectives of this paper are to predict life years lost associated with obesity-related diseases (ORDs) for U.S. non-smoking adults, and to examine the relationship between those ORDs and mortality. Data from the National Health Interview Survey, 1997–2000, were used. We employed mixed proportional hazard models to estimate the association between those ORDs and mortality and used simulations to project life years lost associated with the ORDs. We found that obesity-attributable comorbidities are associated with large decreases in life years and increases in mortality rates. The life years lost associated with ORDs is more marked for younger adults than older adults, for blacks than whites, for males than females, and for the more obese than the less obese. Using U.S. non-smoking adults aged 40 to 49 years as an example to illustrate percentage of the life years lost associated with ORDs, we found that the mean life years lost associated with ORDs for U.S. non-smoking black males aged 40 to 49 years with a body mass index above 40 kg/m² was 5.43 years, which translates to a 7.5% reduction in total life years. White males of the same age range and same degree of obesity lost 5.23 life years on average – a 6.8% reduction in total life years, followed by black females (5.04 years, a 6.5% reduction in life years), and white females (4.7 years, a 5.8% reduction in life years). Overall, ORDs increased chances of dying and lessened life years by 0.2 to 11.7 years depending on gender, race, BMI classification, and age.     

An active-site-directed irreversible inhibitor of delta 5-3-ketosteroid isomerase

The α and β isomers of spiro-3-oxiranyl-5α-androstan-17β-ol were tested as possible inhibitors of Δ⁵-3-ketosteroid isomerase of $\text{Pseudomonas}\text{testosteroni}$. The β-oxirane causes a first-order irreversible inactivation of the enzyme and shows saturation kinetics (K_I, 17 μM). Protection against inactivation is exhibited by 19-nortestosterone, a competitive inhibitor of the isomerase. Although the α-oxirane was found to be a good reversible inhibitor (K_i, 21 μM), prolonged incubation with it failed to produce any inactivation of the isomerase. The results obtained are consistent with the presence of a nucleophilic group situated near the 3-keto group of the substrate in the enzyme-steroid complex.