Decelerating growth and human breast cancer

BACKGROUND: Improved understanding of human breast cancer growth rates may have many clinical applications. Previous reports have used small numbers of patients and assumed an exponential growth rate. METHODS: The exponential equation and the most commonly used decelerating growth equations, the Gompertz equation and seven generalized forms of the logistic equation, were fitted to mammographic measurements of primary breast cancer using the least squares method. An average of 3.4 observations was made in 113 patients, whereas two measurements were made in another 335 patients. Tumors were assumed to originate as a single cell with the lethal tumor volume assumed to be 2(40) cells. RESULTS: All decelerating equations tested provided a better fit than the exponential, whereas a form of the logistic equation provided the best fit to the data. Limitations in the number of tumor measurements, the assumption of maximal tumor size, and biases inherent in the method of data collection are reviewed. These observations suggest families of curves that characterize breast cancer growth during the early period of clinical observation. CONCLUSIONS: Breast cancer growth in the early clinical period was modeled by a form of the logistic equation. The exponential equation fit the data least well.     

Lecithin:cholesterol acyltransferase deficiency: identification of a causative gene mutation and a co-inherited protein polymorphism

We have recreated and expressed two known natural mutations within the LCAT gene which were reported on both alleles in a single case of familial LCAT deficiency. We demonstrate that the Ala-93-->Thr mutation is responsible for the biochemical defect while the Arg-158-->Cys mutation is a co-inherited natural polymorphism of LCAT which results in normal enzyme function.     

Molecular genetics of Wilms'' tumour

The cardiopulmonary response elicited by intravenous bacteria or endotoxin is well characterized in swine and has two major components. The first represents the acute pulmonary and broncho-constrictive phase (0-2 h) and the second phase (3-8 h) represents increased microvascular permeability, hypotension, and enhanced leukocyte-endothelial adhesion. The pulmonary vasoconstriction and bronchoconstriction of phase 1 results in acute pulmonary hypertension and airway dysfunction, which may result in rapid mortality. Because this acute pulmonary response may not mimic the development of human septic shock, we sought to block this early phase and examine the role of tumor necrosis factor in the latter septic phase (3-8 h). Employing a thromboxane A2 (TXA2) receptor antagonist (BAY U 3405) in the presence of LD100 Escherichia coli challenge, we blocked the acute pulmonary hypertensive phase and prevented early mortality, however, TXA2 blockade did not affect the latter development of septic shock and death. This latter lethal phase, characterized by prolonged leukopenia, was blocked in a dose-dependent manner by tumor necrosis factor monoclonal antibody. We conclude that the TXA2-blocked E. coli-challenged swine may provide a novel animal model in which to investigate the pathophysiology of acute septic shock.     

Thermo- and photoelectric current in hornet cuticle

Thermoelectric and photoelectric currents were measured in the cuticle of hornets. The spontaneous current in the studied specimens ranged between 30-40 nAmp under conditions of darkness whereas under illumination the current drops to near zero. Upon warming up to 28-29 degrees C, the current rises to 50-200 nAmp but subsequently, after a while, it declines, regardless of whether the temperature is held steady, continues to rise or is lowered. In light, the current values are lower than in darkness and this under all conditions. When the specimen is charged with an electric current under fixed temperature, the current attains several microAmp in darkness but is usually less than that under illumination by about one order of magnitude. The capacitance values range between 1-7 mFarad both in light and in the dark. Possible mechanisms for creating this cuticular current and the changes which it undergoes under the various experimental conditions are discussed, and so also the properties of hornet cuticle as a semiconductor and possible applications of the described phenomena in everyday life of hornets.