Venous Exit Research Articles

Patterns of the Cranial Venous System from the Comparative Anatomy inVertebrates. Part III. The Ventricular System and Comparative Anatomy of the Venous Outlet of Spinal Cord and Its Homology with the Five Brain Vesicles.

Ontogenetically, the ventricular venous systemmay develop in order to drain the gray matter(cells of the mantle layer of the neural tube) which migrates dorsally. On primitive brain vesicles of submammals especially fish, amphibianand reptile, the ventricular venous system is the major venous collector located on the middorsal surface, in between the meningeal layers comparable to the subarachnoid space in mammals. The ventricular venous system functions as a major drainage system for the brain vesicles in these submammals but its role decreases when the other two venous systems develop. Concerning the route of venous exit from the brain vesicles, we found that it resembles the spinal cord but could not be found all the way along the brain vesicles.

Animal-to-human extrapolation using compartmental models

We have been studying how to use compartmental models to reliably extrapolate toxicological experimental results from one animal species to another with the ultimate goal of useful extrapolation to man. We have taken, as the fundamental core of our analysis, the physically necessary equations describing mass balance. These equations are the classical Fickian equations of the form VdC/dt = Q(a - v). These equations are not a complete set since they are insufficient to provide estimation of venous, arterial, or tissue concentrations with time. Therefore, the mass balance equations must be augmented with additional phenomenological relations to permit the desired calculations. Many investigators use the venous exist condition. While it is clear how to extrapolate the mass balance equations from one sized animal to another or from one species to another, it is not clear how to extrapolate the venous exit condition. In this research we have evaluated the venous exit condition by comparing it with approximate analyses of perfusion and substance diffusion in the tissue.

Apical entry of single main renal artery

Two cases of extrahilar entry of a single main renal artery are described. Selective renal angiography demonstrated arterial entry through the upper pole of the kidney and venous exit, adjacent to the arterial entry. Embryologic as well as some surgical aspects are presented. To our knowledge only one similar variation of arterial supply to the kidney has been reported previously.

The nature of the venous systems in the adrenal gland.

Previous reports have suggested that the conversion of nor-adrenaline to adrenaline is dependent on very high plasma levels of glucosteroids. It has been postulated that this is achieved because the very high level of glucosteroid in the adrenal cortical venous effluent preferentially perfuses the phaeochromocytes before entering the main adrenal vein. No evidence for this portal circulation has been found. It has now been demonstrated that the venous drainage from the phaeochromocytes enters the large venous trunks emerging from the adrenal cortex and not the reverse. The adrenal gland is a composite gland made up by the incorporation by the adrenal cortex of chromaffin tissue during foetal life at a stage when the primitive vasculature of the cortex has already been laid down. The current data suggest that there are two circulations in the adrenal gland, one cortical and the other medullary, and that although the two become closely interlinked during foetal life, some independence remains in adult life. The cortical circulation consists of the cortical arteries and their veins which drain into large trunks at the corticomedullary interface and then directly via larger trunks into the central vein. The medullary circulation consists of the medullary arteries of Flint and their venae comites enclosed in a capsular sheath and an alternative venous exit via the delicate, spidery sinusoids which enter the radicles of the central vein. There is a limited alternative route for cortical blood via the venae comites of the medullary arteries.

Heat and matter distribution in body tissues and the determination of tissue blood flow by local clearance methods

Differential forms of Fick's perfusion principle are combined with the heat conduction and matter diffusion equations and a metabolic term to give partial differential equations for the distribution in space and time of heat and matter in living, perfused tissues at the millimeter level of observational detail. The theory is characterized by well-known parameters local rate of blood flow per unit volume of tissue, diffusion, heat conduction and solubility coefficients of the substance of interest in the tissue, rate of production or consumption of the substance of interest per unit volume of tissue, and a venous exit parameter relating instantaneous concentrations in a volume element of tissue and in venous blood issuing from that volume element. The heat distribution case is illustrated by analyzing existing steady state (time independent) and transient (time dependent) data obtained by the Gibbs thermoelectric probe method for determining tissue blood flow. Fluctuation properties of capillary blood flow are used to help explain the steady state data. A possible general role of such fluctuations in tissue metabolic regulation is conjectured. Methods are given for analyzing the transient data to obtain tissue blood flow. The matter distribution case is illustrated by application to Kety's radioactive tracer local clearance method.

Cardiac output and total peripheral resistance in anesthesiology; clinical applications.

Total peripheral resistance is defined and measured in terms of the force required to maintain blood flow from the root of the aorta to the venous exit into the auricles. Observing changes only in blood pressure and heart rate may not suffice in the management of anesthesia for complicated and prolonged operations in poor-risk patients. In these difficult situations the most important problems are the prevention and treatment of circulatory derangements. The stroke-volume (pulse-pressure) formulas are ideal for the investigation of problems involving acute fluctuations in blood pressure. The clinical anesthesiologist can estimate cardiac output and total peripheral resistance with ordinary clinical data. The most valuable clinical application of the stroke-volume formulas has been to evaluate and interpret the pressor effect of 90-degree passive elevation of the lower extremities (the L position or maneuver). The L maneuver is a clinical aid in the management of cardiovascular changes associated with anesthesia.

Bone Carcinoma Secondary to Carcinoma of the Urinary Bladder

Bone carcinoma as a metastatic manifestation of carcinoma elsewhere is initially a lesion of the bone marrow. Piney (1) states: “At birth all the bones of the skeleton except the cranium contain red marrow in which there is no fatty tissue. The vertebræ, sternum, and os innominata contain red marrow throughout life and only a microscopic amount of fat even in advanced age. The ribs are also storehouses of red cellular marrow throughout life but in advanced age a patch of fatty tissue usually appears at the anterior end of each rib and extends for one inch from the costochondral junction.” This metamorphosis occurs in the long bones in the epiphyses and just below the middle of the shaft and spreads distally more rapidly than proximally, and most rapidly in the distal limb bones. A small patch of red marrow persists in the upper end of each femur and humerus. The vessels of the red marrow are wide and numerous and the velocity of the blood stream is slow. Piney was unable to demonstrate lymphatics in the marrow. He states that metastases are always in the red cellular marrow and showed the presence of carcinoma cells in endothelial-lined channels, quoting Erbholz as having shown red blood cells in carcinoma containing endothelial-lined channels. The points of emergence of tumor on bone surface correspond to places of venous exit from the bone. The site of the earliest deposit is in the medullary cavity at the lower edge of the red marrow in the proximal bones of the limbs and the metastases spread in either direction from their original focus, the proliferation being preceded by an increase in the amount of red cellular marrow. If hyperplasia of the marrow has been evoked by previous anemia the first deposit may be in the lower part of hyperplastic red marrow. The knowledge contributed by Piney favors the embolic origin of osseous metastases. The passage of the pulmonary barrier can be accounted for by the work of Schmidt, who demonstrated the presence of secondary foci in small pulmonary thrombi. These foci may remain latent, only exceptionally disseminating in the systemic circulation. Carcinoma of the urinary bladder as a primary focus for osseous metastasis is rare if available statistics can be considered as an indication of its frequency. Ewing (2) does not mention it. The overwhelming preponderance of prostatic carcinoma over bladder carcinoma as a cause for metastatic bone lesions is not in the same ratio as the relative incidence of the primary lesions. The more abundant lymphatic supply of the prostate may be a partial explanation for this difference, and the compact situation of the prostate may favor dissemination, whereas the pressure relations in the bladder permit intra-luminal growth which, in consequence, often assumes a papillary character. H. G. Wells (3) states that Schraut, in 1854, described cases of urinary bladder carcinoma with osseous metastases and that Kastner, in 1908, also described such cases.