Comparison of blood flow and myoelectric measurements in two chronic models of mesenteric ligation.

OBJECTIVE: To determine whether the predictive accuracy of intestinal motility and blood flow measurements is altered by the magnitude of ischemic damage. DESIGN: Inception cohort study (dogs). Motility was measured using a probe that quantifies both the electromyographic (EMG) measurements and the magnitude of evoked contractile response (ECR). Intestinal blood flow was assessed using Doppler ultrasonography in the marginal artery and perfusion fluorometry, which quantifies fluorescein in the bowel wall in dye fluorescence units. SETTING: Vivarium animal research facilities at a medical school. INTERVENTIONS: The blood supply of a 40-cm length of ileum was ligated in 102 dogs: 52 in which the marginal artery was ligated at two points 8 cm apart (severe model), and 50 in which the marginal artery was ligated only once (moderate model). Twenty-four hours after ligation, the motility and blood flow parameters were measured in normal bowel and at 2-cm intervals within the 40-cm ischemic segment. Resection and anastomosis of ischemic bowel was then performed using either EMG, ECR, or fluorometry to determine the site of resection. OUTCOME MEASURE: Anastomotic leak from progressive ischemia. RESULTS: There were 26 fatal anastomotic leaks, all due to necrosis at the anastomosis. Perfusion fluorometry and ECR measurements did not correlate with survival in either model. An audible Doppler pulse in the marginal artery correlated with survival in the moderate (P < or = .02) but not the severe model (P = .59). The EMG measurements were significantly greater in survivors vs nonsurvivors in both models. CONCLUSIONS: The EMG measurements may be useful in bowel viability assessment. Correlation of Doppler ultrasonographic findings with survival in the moderate model suggests that blood flow measurements may be more reliable in predicting viability in less ischemic bowel.

Comparison of commercial kits for detection of cryptococcal antigen.

Although kits to detect cryptococcal antigen are used widely to diagnose cryptococcal infection, the comparative performance of commercially available assays has not been evaluated in the past decade. Therefore, we compared the sensitives and specificities of five commercially available kits for detecting cryptococcal antigen (four latex agglutination test kits--Calas [Meridian Diagnostics])--Crypto-LA [International Biological Labs], Myco-Immune [MicroScan], and Immy [Immunomycologics]--and an enzyme immunoassay kit, Premier [Meridian Diagnostics]) with culture for the diagnosis of cryptococcal meningitis and fungemia. Of 182 cerebrospinal fluid (CSF) and 90 serum samples submitted for cryptococcal antigen and fungal culture, 49 (19 and 30 samples, respectively) from 20 patients had a culture positive for Cryptococcus neoformans. For CSF specimens, the sensitivities and specificities of all kits were comparable (sensitivity, 93 to 100%; specificity, 93 to 98%). There was a significant difference in sensitivities of the kits when serum samples were tested with the International Biological Labs and MicroScan kits, which do not pretreat serum with pronase. These kits were less sensitive (sensitivity, 83%) than the Immy and Meridian latex kits (sensitivity, 97%), which do pretreat with pronase. The sensitivity of the Meridian enzyme immunoassay kit was comparable to that of the pronase-containing latex kits. These kits were of equivalent specificities (93 to 100%) when testing serum. Some of the currently available kits have limitations that need to be recognized for proper interpretation of results. Specifically, the use of pronase on serum samples reduces the number of false-positive results, and a titer of < or = 1:4 can be a false-positive result when CSF samples are being tested.

Cutaneous metastasis of neuroendocrine carcinoma of uterine origin.

We report a case of a 33-year-old woman who presented with the rapid development of multiple dermal and subcutaneous nodules on the chest, back, abdomen, axilla, neck, and scalp. These nodules were firm, tender, and non-ulcerated and measured from 0.2 to 1.2 cm in diameter. A punch biopsy of one of the subcutaneous nodules in the scalp showed a poorly differentiated carcinoma in the reticular dermis with light microscopic, immunohistochemical, and ultrastructural features supporting neuroendocrine differentiation. The past medical history was significant for a recent total abdominal hysterectomy for carcinoma of the cervix at another hospital, originally characterized as a poorly differentiated adenocarcinoma of the cervix and lower uterine segment. Review of the microscopic slides of the uterine neoplasm revealed features suggesting a more appropriate classification as a primary neuroendocrine carcinoma; this was subsequently confirmed by immunophenotyping and ultrastructural evaluation. This is the first reported case of a uterine neuroendocrine carcinoma metastasizing exclusively to the skin. It further illustrates the important contribution of dermatopathology to the understanding of a systemic pathologic process.

Intraoperative assessment of bowel viability.

Viability of ischemic bowel was assessed in 30 dogs after mesenteric arterial ligation in a 40-cm length of ileum. Viability was evaluated using two gross features, color and peristalsis, and four objective methods including bowel wall surface oximetry (pO2), Doppler ultrasound, quantitative fluorescein fluorimetry, and myoelectric activity measured by a strain gauge probe. Each parameter was measured at 2-cm intervals within the 40-cm ischemic segment before resection and anastomosis was performed. There were seven fatal anastomotic leaks, all due to further bowel necrosis. Survival did not correlate with bowel color, presence of peristalsis, bowel wall pO2 Doppler ultrasound, or the myoelectric parameters. However, fluorescein fluorimetry was predictive of long-term viability. These results suggest that quantitative fluorescein fluorimetry may be a useful adjunct in intraoperative bowel viability assessment.

Constitutive equations of erythrocyte membrane incorporating evolving preferred configuration.

The erythrocyte membrane is modeled as a two-dimensional viscoelastic continuum that evolves under the application of stress. The present analysis of the erythrocyte membrane is motivated by the recent development of knowledge about its molecular structure. The constitutive equations proposed in the present analysis explain in a consistent manner the data on both the deformation and recovery phases of the micropipette experiment. The rheological equations of the present study are applied in a later section to the analysis of a plane membrane deformation that is quantitatively similar to the tank-treading motion of the erythrocytes in a shear field. The computations yield useful information on how the membrane viscosity becomes a more dominant feature in tank-treading motion. The material constants appearing in the proposed constitutive equations may be useful indications of the biochemical state of the membrane in health and disease.