Phenoxybenzamine-a mediator of blood oxygen affinity

Studies of the effect of phenoxybenzamine on oxygen transport have been concentrated on flow and resistance changes. Previous studies have ignored the possible effects of phenoxybenzamine on the ability of red blood cells to offload oxygen itself. After an initial inhibitory effect phenoxybenzamine greatly enhances the ability of the red cell to offload oxygen under conditions seen at the tissue level. The disparity between P50std and organic phosphate changes found in this and other studies warrants extreme caution to be used in interpreting results where P50 itself is not measured.     

High-speed simulation of discrete dynamic probabilistic systems

The theory and design of a special purpose stochastic computer for the high-speed simulation of Markov chains and random walks is described. Experimental results are presented for the transient and steady response to Markov systems and for fundamental studies of random walks. The paper conlcludes with a discussion of the extension of the system to the Monte-Carlo solution of partial differential equations with arbitrary boundary conditions.     

The use of graphics in a computer-based urban information system

This paper describes the development of an interactive graphics system for the display of planning information in urban areas. It outlines the objectives of the system and explains the content and structure of the various data files. It goes on to explain the user operating environment and the provision of suitable graphics facilities. By way of examples it demonstrates the potentialities of the system.     

Age-dependence of hepatic dimethylnitrosamine-demethylase activity in the rat

The mixed-function oxidase which activates the carcinogen dimethylnitrosamine (DMN) was determined in the rat liver as a function of animal age. DMN-demethylase activity increased considerably at first to reach a maximum on day 29, and then substantially decreased to day 59; thereafter, enzyme activity remained essentially stable up to at least day 110. Pretreatment with 3-methylcholanthrene, which caused a pronounced decrease in this enzyme activity, did not affect the general shape of the age-dependence curve. The results suggest that rats between weaning and sexual maturity are more susceptible to the carcinogenic effects of pulse doses of DMN than are neonates or adult animals.     

Hamster brown-adipose-tissue mitochondria. The role of fatty acids in the control of the proton conductance of the inner membrane

The specific ability of fatty acids to increase the proton conductance of the inner membrane of mitochondria from the liver and brown adipose tissue of cold-adapted hamsters was compared. The liver and brown-adipose-tissue mitochondria had their effective proton conductances increased by respectively 0.028 and 0.94 nmol H+- min-1. (mV of proton electrochemical gradient)-1 for each nmol of palmitate bound. No difference could be detected between the abilities of liver and brown-adipose-tissue mitochondria to bind fatty acids. Purine nucleotides did not displace farry acids from the brown-adipase-tissue mitochondria. The endogenous fatty acid content of hamster brown-adipose-tissue mitochondria prepared in the absence of album was found to be equivalent to 17 +/- 7 nmol of palmitate/mg protein. The fatty acid content was reduced to 1 nmol/mg after preincubation of the mitochondria with CoA, ATP and carnitine. No inert pool of fatty acids could be detected. The endogenous fatty acids of hamster liver mitochondria were less than 4 nmol of palmitate equivalent/mg protein. Some of the fatty acid associated with the brown-adipose-tissue mitochondria originates during preparation of the mitochondria. In the light of these results, the physiological role of the fatty acids in controlling the proton conductance of the brown-adipose-tissue mitochondrial inner membrane, and hence- non-shivering thermogenesis, is re-evaluated.     

Pain in gynecologic practice

This paper has given a general discussion of the spectrum of pain complaints presented to the gynecologist. Specific information about pain sensation and localization has been reviewed together with the gynecologic causes of acute abdominal pain. Chronic pain has been classified as episodic or continuous, and the causes, mechanisms, diagnosis and treatment of episodic and chronic pelvic pain have been presented. The concluding remarks have outlined some diagnostic considerations for the patient with chronic pain. (The interested reader will find more extensive information on these subjects in the articles listed in the bibliography.).     

A comparative study of skin tests and determination of the serum level of specific IgE immunoglobulins by means of the radioallergosorbent test in subjects with atopy

On 73 patients suspected for atopic diseases, 258 skin tests and radioallergosorbent tests (RAST) for specific IgE in serum were carried out. The results of both tests were compared in connection with the clinical picture. A good qualitative positive correlation was found, especially for grass pollen and house dust. False positive results with RAST cannot be excluded. The RAST seems to be a valuable adjunct to extensive allergologic diagnostic investigation, particularly in cases where difficulties can be expected in the performance or the interpretation of skin tests.     

A flavinogenic mutant of the yeast Pichia guilliermondii with impaired iron transport

We recently demonstrated that net fluid uptake occurs in the capillary system of the inner medulla. To define the site of fluid uptake, the concentration of protein was determined in plasma from descending vasa recta at the base and tip of the exposed papilla in Munich-Wister rats. The vasa recta plasma-to-arterial plasma protein concentration ratio (VR/P) was 1.43 +/- 0.09 at the base and 1.66 +/- 0.09 at the tip. These results, which indicate fluid loss from the descending vasa recta, are difficult to explain on the basic of hydraulic and oncotic forces alone. The osmolality of the contents of descending vasa recta increased between base and tip (delta = 72 +/- 30 mosmol/kg H2O). If the increase in osmolality of plasma in descending vasa recta lags behind that of the adjacent medullary interstitium, a transcapillary osmotic driving force exists favoring water loss from descending vessels. It is concluded that fluid uptake by the inner medullary circulation occurs beyond descending vasa recta in interconnecting capillaries or ascending vasa recta. In our view the most likely interpretation of these results is that fluid movement across vasa recta in the inner medulla is influenced by three forces: those owing to transcapillary differences in osmotic, oncotic, and hydraulic pressures.