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Biomedical subjects

J A Rossi

Publications and source records attributed to J A Rossi.

11 recordsLinked to original sources
PubMed1989

Hemodynamic performance of carotid artery shunts.

Although the use of shunts for carotid artery surgery remains controversial, the hemodynamics of the shunts currently available have not been carefully evaluated in vivo. We developed an animal model using contralateral carotid artery ligation, which produced ipsilateral carotid blood flows (640 +/- 44 ml/min) and internal carotid stump pressures (52 +/- 4 mm Hg) over a range commonly seen in carotid artery surgery. Seven shunts were tested and included Javid; 10F and 8F Brener; and 14F, 12F, 10F, and 8F Argyle shunts. The hemodynamic features evaluated for each shunt included maximum shunt flow, the pressure gradients occurring across each shunt, the increase in cerebral perfusion pressure over occlusion pressure associated with shunt placement, and the distal pressure pulse waveform. The larger diameter shunts were consistently better than the smaller diameter shunts. The correlation between shunt flow and the increase in distal pressure produced by shunt placement was high (r = 0.98, p less than 0.05), confirming that high flow rates maintained high perfusion pressure. By relating maximum shunt flow and the pressure gradient to the change in the pressure pulse contour for each shunt, it could be demonstrated that at the larger diameters, straight shunts displayed superior hemodynamic characteristics compared with tapered shunts, whereas at smaller diameters, tapered shunts were superior.

Animals↗
PubMed1989

Alteration of the submandibular glands of female mice during pregnancy and lactation. A histological, histometric and histochemical study.

The submandibular glands of mice show "masculinization" during pregnancy and lactation. In this work involving morphological, morphometric and histochemical analyses we observed an increase in the volume fraction and area of the granular ducts and the apical granulation of their cells. The maximum response to the masculinization occurred on the 15th day of pregnancy. From this day on a decrease in the volume fraction of the granular ducts starts, even though the gland keeps the "masculine pattern" throughout the end of the lactation phase. Our observations support the intermodulation between striated and granular ducts. In our opinion, the "masculinization" process of the submandibular gland is related to the progesterone increase which takes place during pregnancy; its maintenance during lactation is also connected to prolactin.

Animals↗
PubMed1987

Flow cytometric analysis of relative mean DNA content of urogenital cancer cells in fresh and paraffin-embedded materials.

The relative mean DNA content calculation was performed by flow cytometry on single cell suspensions prepared from fresh and paraffin-embedded specimens of 10 patients with surgically resected urogenital cancer. Samples were processed by a modified method of Hedley et al. including two hours of pepsinizing time, ribonuclease digestion, and propidium iodide staining. The mean DNA content which is a quantitative description of flow cytometric characteristics was significantly correlated between the fresh and paraffin-embedded materials (n = 10, r = 0.869, p less than 0.01). This method allows for the objective, retrospective analysis of DNA content in relation to diagnosis and prognosis of urogenital cancer.

DNA, Neoplasm↗
PubMed1986

External duodenal fistula. Causes, complications, and treatment.

We reviewed records of 18 patients with external duodenal fistula. Fourteen patients developed duodenal fistulas following an operation, two following abdominal trauma, and two as a complication of other diseases. Copious drainage of intestinal juice from the abdomen was the most common presenting sign. Contrast fistulography, upper gastrointestinal tract roentgenography, and T-tube cholangiography were useful diagnostic studies. Nine patients were treated nonoperatively; nine patients required at least one operation. Complications occurred frequently; of special interest were three patients who developed postoperative acute cholecystitis. Six patients died (33% mortality). Factors associated with mortality were advanced age (greater than 65 years), uncontrolled infection and multiple organ failure, high-output fistula, malnutrition, delay in diagnosis (more than three days), and multiple reoperations to treat the fistula or complications. External duodenal fistula continues to be a life-threatening problem whether it is postoperative, posttraumatic, or secondary to a disease process.

Abdominal Injuries↗
PubMed1980

Oxygen consumption and insensible water loss in premature infants under radiant heaters.

Oxygen consumption ((Vo2), carbon dioxide production (Vco2), and insensible water loss (IWL) were measured simultaneously in nine nondistressed, appropriately grown, premature infants less than 2 weeks old, nursed in a conventional, blow-warmed incubator, and were compared with measurements made on the same infants under a radiant heater. The infants had a pronounced increase (148% on average) in IWL when under the radiant heater (P < .001) whereas Vo2 increased by only 4.6% (P = .073). Abdominal skin temperature (servocontrolled to maintain 36.5 C) and esophageal temperature were the same under both conditions, but ambient air temperature was 0.7 C higher in the incubator (P < 05). Although a positive correlation was found between the increase in IWL and the change in Vo2 (r = .75, P < .01), the large increase in IWL (and, therefore, evaporative heat loss) under the radiant heater is out of proportion to, and cannot be accounted for, by the change in metabolic heat production. The heat transfer processes involved in maintaining body temperature constant under these conditions require further study.

Body Temperature Regulation↗
PubMedDate not supplied

An informatics approach to complex research problems. Dynamic process modeling.

In the nursing literature, the term computer simulation refers exclusively to an educational tool that requires the user to respond to simulated events and to engage in the decision-making process. However, computer simulations are frequently constructed to model dynamic systems (systems that change with time) and to randomly simulate real life events in an effort to study complex problems. In this context, computer simulation is a research methodology and is used in a wide variety of disciplines including the behavioral sciences and business management. Nurses will inevitably encounter research studies where computer simulation has been employed. It is also very likely that this methodology will be used as a nursing research tool in the near future. This article introduces and describes the use of computers to model dynamic systems, the theory that supports simulation modeling as a research methodology, and the issues of model validation. Included are examples of four different research problems from diverse fields of study where computer simulation has been applied.

Computer Simulation↗