THE PROBABLE ORIGIN OF ORYZOPSIS CONTRACTA

Oryzopsis contracta is found only in the Big Hollow area of southern Wyoming where it exists sympatrically with the widely distributed species O. hymenoides and O. micrantha. The three species are probably reproductively isolated from each other. Oryzopsis contracta is very similar to O. hymenoides; however, they can be separated on several characters. It also resembles O. micrantha in several characters. This suggests that O. contracta may have evolved through hybridization between the other two species. A quantitative analysis shows that O. contracta occupies an intermediate and central position between the other two species with regard to most characters analyzed. Scatter diagrams reveal a correlated deviation of O. contracta individuals from O. hymenoides toward O. micrantha with respect to several characters. Meiosis in occasional sterile O. hymenoides × O. contracta hybrids shows multivalent associations, suggesting that an appreciable part of the presumed micrantha contribution to the contracta genome was in the form of relatively large chromosome segments. The data suggest that O. contracta evolved as a result of chromosomal translocations in a chance hybrid between O. hymenoides and O. micrantha followed by backcrossing to O. hymenoides and subsequent self-fertilization of the hybrid.     

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.     

Interfacial water and its potential role in the function of sericin against biofouling

Abstract

Silk sericin is a globular protein whose resistance against fouling is important for applications in biomaterials and water-purification membranes. Here it is shown how sericin generates a water-exclusion zone that may facilitate antifouling behavior. Negatively charged microspheres were used to mimic the surface charge and hydrophobic domains in bacteria. Immersed in water, regenerated silk sericin formed a 100-µm-sized exclusion zone (for micron-size foulants), along with a proton gradient with a decrease of >2?pH-units. Thus, when in contact with sericin, water molecules near the surface restructure to form a physical exclusionary barrier that might prevent biofouling. The decreased pH turns the aqueous medium unviable for neutrophilic bacteria. Therefore, resistance to biofouling seems explainable, among other factors, on the basis of water-exclusionary phenomena. Furthermore, sericin may play a role in triggering the fibroin assembly process by lowering the pH to the required value.