[Cystatin C: Biomarker of cardiovascular risk in HIV]

INTRODUCTION

Patients infected with the human immunodeficiency virus (HIV) have a higher cardiovascular risk (CVR). The development of cardiovascular disease (CVD) in this population involves traditional CVR factors and factors related to the infection itself, such as chronic inflammatory status, immune dysfunction, as well as the antiretroviral therapy received. Cystatin C (CC) has shown to be useful in assessing the presence of CVR factors and CVD established in the general population, the elderly population, and patients with chronic kidney disease. An analysis was performed on this association in an HIV positive population (HIV+).

MATERIAL AND METHODS

Analytical, observational, cross-sectional study was conducted, and included collecting information about CVR factors and CVD in HIV+, as well as measuring CC. The patients were divided into 2 groups: Group1=high CC (≥0.95mg/L) and Group2=normal CC (<0.95mg/L).

RESULTS

A total of 95 patients were included. Group1=27 (28.4%) and Group2=68 (71.5%). A value of CC≥0.95mg/L was related to the presence of CVD (P=.01). It was also related with and an increase in waist circumference (P=.05), neck circumference (P=.04), systolic blood pressure (P=.04), diastolic blood pressure (P=.01), Framingham score (P=.03), and Framingham score adapted for HIV (P=.01). After performing multivariate analysis with incorporation of variables associated with CVD in the bivariate analysis, only CC≥0.95mg/L continued to be related to CVD.

CONCLUSION

CC≥0.95mg/L was independently associated with CVD. This cut-off point was also linked to higher levels of blood pressure, and higher CVR at 10 years using the Framingham Score and Framingham Score adapted for HIV population.

The impact of insurance company mandated compression stocking trial on rate of intervention in patients with symptomatic venous reflux disease

OBJECTIVE

Insurance companies have criteria for a venous intervention to be a covered procedure, including symptoms, vein size, and a trial of conservative therapy with compression stockings. The goal of this study was to see the impact of such mandated stocking use on ultimate intervention.

METHOD

A retrospective review was done of prospectively gathered data entered in the electronic medical record. Two-hundred consecutive new patients evaluated at our vein center were included.

RESULTS

Forty-four of the 200 patients did not require any procedures and 39 patients had procedures scheduled for small or asymptomatic venous changes that did not meet insurance criteria. This left 117 patients with venous symptoms in whom evaluation concluded that a corrective procedure could be performed. These interventions included largely radiofrequency ablation and phlebectomy. Of these 117 patients, 48 had previously used compression stockings. In the remaining 69 patients, stockings were provided on the day of initial consultation and these 69 patients served as the subjects for this review. At three month follow up, one patient reported the stockings help enough that she did not want to pursue correction. Two patients had continued pain and were planning correction once other unrelated issues resolved. Three patients said they never wore the stockings. Sixty-one patients had procedures performed. The average length of stocking use in patients who chose corrective procedures was 103 days. One patient could not be reached.

CONCLUSION

Of the patients that reported they used the stockings as prescribed, one chose chronic stocking therapy and 63 patients either had procedures or were planning procedures. Use of prescription stockings was effective in avoiding intervention in one of 64 cases (2%), despite an average trial of 103 days. These results cast doubt on the merits of the use of an insurance company mandated stocking trial.

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.

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.

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.

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.

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.

Flashlight-size external cavity semiconductor laser with narrow-linewidth tunable output

We describe the construction of a compact and relatively inexpensive external cavity to be used with III-V compound semiconductor injection lasers. The operation of a typical GaAs diode in the cavity and some of the limiting performance factors are discussed.