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Biomedical subjects

A Dobson

Publications and source records attributed to A Dobson.

At least 127 records · Page 7Linked to original sources
PubMed1979

On the presence of a ductus venosus in the fetal pig in late gestation.

Evidence is presented to show that there is a functional bypass in the liver of the fetal piglet between the umbilical vein and the posterior vena cava. Injections of labelled microspheres (14 micrometer) into the umbilical vein in six fetuses in late gestation resulted in the appearance of radioactivity in the arterial blood and throughout the tissues of all piglets. About 60% of the umbilical venous blood bypassed the liver whereas in a fetal foal, injection in a similar manner, no evidence for a shunt was found. Radiographic studies confirmed the presence of a large vascular connection, equivalent to the ductus venosus, between the umbilical vein and posterior vena cava in the fetal piglet.

Animals↗
PubMed1976

Absorption and exchange of water across rumen epithelium.

The osmotic pressure of solutions in the ventral sac of the rumen of the conscious cow was varied with Na Cl or mannitol. The mucosal blood flow measured by HTO clearance was minimal when the lumen contained an isotonic solution and rose threefold when the rumen was hypo- or hypertonic to plasma by 150 mosmol/kg. Thus osmotic gradients actoss the rumen epithelium stimulated mucosal blood flow. Using osmotic gradients small enough to avoid blood flow stimulation, the net water flow could be enhanced by butyrate, a chemical stimulator of blood flow. Thus water movement was partially limited by blood flow. This implied an appreciable change in osmotic pressure of the capillary blood toward that of the rumen contents. The relative importance of blood flow, membrane permeability, and solute uptake on water transport was assessed. The osmotic pressure in the rumen was stationary when the rumen solution was distinctly hypotonic to plasma. The absorbate in the absence of an osmotic gradient was thus hypertonic. The net uptake of solute increased rapidly when the solution in the lumen was hypertonic to plasma. This gave rise to a more rapid rate of change of osmotic pressure in the rumen under this condition.

Absorption↗
PubMed1976

Dependence of Cr-EDTA absorption from the rumen on luminal osmotic pressure.

A method for the measurement of [51Cr]EDTA absorption from the ventral sac of the rumen with an error of the order of +/-10% is described. When a solution present in the rumen was hypotonic or isotonic, the absorption rate of [51Cr]EDTA expressed as a clearance was about 0.2 ml/min. This gave rise to negligible errors when [51Cr]EDTA was used as an unabsorbed marker to calculate net water movements. When the osmotic pressure in the rumen exceeded that of plasma by 30-40 mos-mol/kg, the absorption rate of [51Cr]EDTA appeared to be related to the degree of hypertonicity. Absorption rates as high as 8 ml/min were observed within a range of osmotic pressures normally encountered postprandially in the rumen. Under hypertonic conditions, a correction for the absorption of this large anion was necessary if passage of water into the lumen were not to be systematically overestimated.

Absorption↗
PubMedDate not supplied

The future of Medicare policy reform.

The Medicare program, the largest health insurance program in the United States, is clearly at a crossroads as it enters its third decade. Historical increases in health care expenditures, plus a changing political and economic landscape, have set the groundwork for policy reform. Two basic reform strategies--reimbursement arrangements and program funding mechanisms--are discussed. In 1983, Congress enacted the Prospective Payment System (PPS) which initiated a fundamental change in the way hospitals are paid for care delivered to Medicare beneficiaries. But the PPS is only a stepping-stone to broader reforms such as capitation. In addition, new methods of program funding may be necessary, especially in light of policymakers' considerations of coverage of services such as long-term care and organ transplants.

Financing, Organized↗
PubMedDate not supplied

Volume of extravascular lung fluid determined by blood ultrasound velocity and electrical impedance dilution.

A hypertonic sodium chloride bolus passing through the lung has a sound velocity transient that is biphasic when it reaches the carotid artery. This transient is compatible with water moving into the hypertonic bolus from the lung parenchyma, thereby leaving the lung parenchyma hypertonic. Subsequently, as the bolus leaves the lung vasculature, water passes from the blood into the tissue to return the lung tonicity to baseline, giving a moment when net movement is zero, an instant of osmotic equilibrium. Concurrent measurements of impedance track the sodium chloride transient. A theoretic basis for the calculation of extravascular lung water is derived from the water transferred to the blood, the amount of sodium chloride moved from blood to the lung, and the increase in blood osmolarity measured at the moment of equilibrium. Examples from measurements on sheep suggest that two intravenous injections of hypertonic and isotonic sodium chloride, with observations of sound velocity and electrical impedance in the systemic arterial circulation (which could also provide the cardiac output), provide a basis for calculation of lung permeability, water and salt movements, and extravascular lung water estimation.

Animals↗
PubMedDate not supplied

What do PPS margins mean? Different things to different groups.

Since the inception of Medicare's prospective payment system (PPS) in 1983, the interpretation of Medicare PPS operating margins has generated much debate and confusion. Numerous estimates often show considerable range from the highest to the lowest within roughly the same time periods. In almost all instances the reason for these differences is attributable to elements of the study design. In this article adapted from a paper he wrote for The Catholic Health Association, Allen Dobson identifies and describes the legitimate reasons for differences among studies of Medicare PPS operating margins. His paper provided a useful framework for reviewing studies of this type. He determined that three sets of factors--statistical, methodological, and interactive--influence the magnitude of margin estimates. Dr. Dobson concluded that the various margin estimates all show essentially the same thing: Margins under PPS have fallen significantly and are likely to continue to do so as long as actual case costs rise more rapidly than actual case revenues. By PPS year 6, few types of hospitals are likely to receive adequate funds from Medicare to cover their expenses.

Costs and Cost Analysis↗