Mathematical model of liver regeneration in human live donors.

Liver regeneration after injury occurs in many mammals. Rat liver regenerates after partial hepatectomy over a period of 2 weeks while human liver regeneration takes several months. Notwithstanding this enormous difference in time-scales, with new data from five human live liver transplant donors, we show that a mathematical model of rat liver regeneration can be transferred to human, with all biochemical interactions and signaling unchanged. Only six phenomenological parameters need change, and three of these parameter changes are rescalings of rate constants by the ratio of human lifespan to rat lifespan. Data from three donor subjects with approximately equal resections were used to fit the three parameters and the data from the other two donor subjects was used to independently verify the fit.

Identification and localization of multiple classic cadherins in developing rat limbic system.

Classic cadherins are multifunctional adhesion proteins that play roles in tissue histogenesis, neural differentiation, neurite outgrowth and synapse formation. Several lines of evidence suggest that classic cadherins may establish regional or laminar recognition cues by virtue of their differential expression and tight, and principally homophilic, cell adhesion. As a first step toward investigating the role this family plays in generating limbic system connectivity, we used RT-PCR to amplify type I and type II classic cadherins present in rat hippocampus during the principal period of synaptogenesis. We identified nine different cadherins, one of which, cadherin-9, is novel in hippocampus. Using in situ hybridization, we compared the cellular and regional distribution of five of the cadherins (N, 6, 8, 9 and 10) during the first two postnatal weeks in hippocampus, subiculum, entorhinal cortex, cingulate cortex, anterior thalamus, hypothalamus and amygdala. We find that each cadherin is differentially distributed in distinct, but highly overlapping fields that largely correspond to known anatomical boundaries and are often coordinately expressed in interconnected regions. For example, cadherin-6 expression defines CA1 and its principal target, the subiculum; cadherin-10 is differentially expressed in CA1 and CA3 in a manner correlating with the organization of interconnecting Schaffer collateral axons; and cadherin-9 shows a striking concentration in CA3. Some cadherin mRNAs are highly restricted to particular anatomical fields over the entire time course, while others are more broadly expressed and become concentrated within particular domains coincident with the timing of afferent ingrowth. Our data indicate that classic cadherins are sufficiently diverse and differentially distributed to support a role in cell surface recognition and adhesion during the formation of limbic system connectivity.

Feasibility of performing a virtual patient examination using three-dimensional ultrasonographic data acquired at remote locations.

OBJECTIVE: To evaluate the feasibility of performing three-dimensional ultrasonographic studies that meet American Institute of Ultrasound in Medicine and American College of Radiology ultrasonographic examination guidelines with review off-line and at remote locations. METHODS: One hundred patients were studied at 2 institutions using high-end two-dimensional clinical ultrasonographic scanners and commercially available three-dimensional ultrasonography for a variety of organ systems (first- and second-trimester fetus, abdomen, and female pelvis). We evaluated several parameters, including measurements, completeness of organ visualization, abnormalities identified, image quality, number of volumes required, and discrepancies between interpretations. RESULTS: Overall, three-dimensional ultrasonography could produce diagnostic-quality results comparable with those of two-dimensional ultrasonography. Three-dimensional ultrasonographic image quality was lower than that of two-dimensional ultrasonography. Two- and three-dimensional ultrasonographic measurements were comparable (<5% difference), as was the extent of organ visualization, although some structures were challenging for both two- and three-dimensional ultrasonography. In general, organs completely imaged in the scanner field of view required 1 to 1.5 volumes, whereas larger organs required between 3 and 6 volumes. Differences among reviewers' interpretations highlighted the need for standardization of acquisition and reviewing protocols for sonographers and physicians. CONCLUSIONS: Our results show that it is clinically feasible to acquire three-dimensional ultrasonographic data at one site and to obtain accurate interpretation by off-line review at another within the context of providing high-quality clinical diagnostic studies.

Intraoperative sonographic localization of breast masses: success with specimen sonography and surgical bed sonography to confirm excision.

OBJECTIVE: To assess the use of intraoperative sonography for localization of breast masses at excisional biopsy, with specimen and surgical bed sonography to confirm excision. METHODS: A computer search of the 5-year period from January 1993 through January 1998 revealed 138 consecutive women referred for sonographically guided excisional biopsy of 148 masses; 35 masses were excluded because they had no postoperative mammograms. One hundred thirteen masses constituted the study group. Specimen sonography (n = 60) or surgical bed sonography (n = 53) was performed as the initial evaluation to confirm excision, but ultimately, surgical bed sonography may have been necessary after specimen sonography, and specimen sonography may have been necessary after surgical bed sonography. The miss rates determined by postoperative imaging were calculated for each group and compared with those of mammographically guided needle localization series from the literature. RESULTS: Follow-up physical examination and mammography showed no residual mass in the region of surgery in any patient. However, follow-up sonography had 1 miss in the initial specimen sonogram group (1 [1.7%] of 60) and 1 miss in the initial surgical bed group (1 [1.9%] of 53). As shown by the Fisher exact test, there was no significant difference between the miss rates of the 2 initial methods of confirming lesion excision or between the miss rates of these initial methods, both groups combined, and 6 mammographic localization series from the literature. CONCLUSION: Intraoperative breast sonography, using specimen sonography and scanning the surgical bed, has miss rates comparable with those of mammographic needle localization. Follow-up sonography must be performed if there is any doubt of complete excision.

Sonographically guided renal mass biopsy: indications and efficacy.

PURPOSE: To review the clinical indications, pathologic results, and success rate of all our sonographically guided solid renal mass biopsies over a 5-year period. METHODS: Between 1993 and 1998, 44 consecutive patients underwent sonographically guided percutaneous biopsy of a solid renal mass. Indications included prior history of nonrenal malignancy, metastatic disease of unknown primary origin, previous contralateral nephrectomy for a renal cell neoplasm, a renal transplant mass, suspected renal lymphoma, history of tuberous sclerosis, and poor surgical candidacy. Aspiration biopsies were initially performed with 22- to 18-gauge spinal needles. If the initial cytologic evaluation findings were nondiagnostic, core biopsies were then performed with 20- to 18-gauge core biopsy guns. Dictated sonographic reports of the biopsies were reviewed to determine the following: indication for biopsy, location and size of the renal mass, needle gauge and type, number of needle passes, and complications. Final cytologic and surgical pathologic records were reviewed. RESULTS: Thirty-six (82%) of the 44 biopsy specimens were diagnostic. Aspirated smears were diagnostic in 24 (67%) of these cases, with the diagnosis made on the basis of cell block alone in an additional 2 (6%). A definitive diagnosis came from core biopsy alone in 10 cases (28%). The 18-gauge core needle yielded diagnostic results more reliably than the 20-gauge core needle, and a significant correlation was seen between core biopsy needle size and the rate of diagnostic core samples (P = .017). Pathologic diagnoses included renal cell carcinoma (n = 18), lymphoma (n = 4), oncocytic neoplasm (n = 4), transitional cell carcinoma (n = 2), angiomyolipoma (n = 1), papillary cortical neoplasm (n = 1), and metastatic carcinoma (n = 6). Complications were seen in 4 (9%) of 44 cases; all were treated conservatively. CONCLUSIONS: For specific clinical indications, sonographically guided fine-needle aspiration and core biopsy of a solid renal mass can be performed safely. In many cases, a definitive diagnosis can be made on the basis of fine-needle aspiration alone. However, diagnosis may ultimately require core biopsy, for which 18-gauge core needles would be more reliably diagnostic than 20-gauge needles.

The role of contrast-enhanced sonography for radiofrequency ablation of liver tumors.

OBJECTIVE: To assess the feasibility and usefulness of contrast-enhanced sonography for tumor detection and guidance of liver VX2 tumor ablation and to evaluate post radiofrequency ablation effectiveness. METHODS: VX2 tumors were implanted into the livers of 6 rabbits. Both conventional and harmonic gray scale and power Doppler imaging were performed with a commercially available scanner to evaluate the liver tumors before and after intravenous injection of a sonographic contrast agent before and after radiofrequency ablation. Contrast-enhanced imaging was used to detect the tumors before ablation, to guide needle insertion, and to measure the ablation sites after radiofrequency ablation. Pathologic examination was performed for comparison. RESULTS: Three tumors were seen without contrast enhancement, whereas 10 tumors (<1 cm) were detected with contrast enhancement. Intentionally, 2 tumors were completely ablated and 5 tumors were partially ablated. In 3 cases, incompletely ablated tumors could only be identified on contrast-enhanced Doppler imaging by enhancing the detection of residual tumor vascularity. There was excellent concordance between sonographic imaging and gross pathologic findings. CONCLUSIONS: Contrast-enhanced sonographic imaging appears useful for detection of liver tumors and for guiding and monitoring tumor ablation therapies.

The role of preoperative radial artery ultrasound and digital plethysmography prior to coronary artery bypass grafting.

OBJECTIVE: Doppler ultrasound and digital plethysmography are used at our institution to determine the suitability of the radial artery for harvest prior to coronary artery bypass grafting (CABG). The purpose of this study is to determine the value of this preoperative evaluation. METHODS: A retrospective analysis of non-invasive radial artery testing was performed on 187 CABG patients. Criteria used to exclude radial arteries from harvest were anatomic abnormalities (size<2 mm, diffuse calcifications), and perfusion deficits during radial artery occlusion (>40% reduction in digital pressure, non-reversal of radial artery flow, or minimal increase in ulnar velocity). A questionnaire was used to determine the incidence of postoperative hand ischemia or rehabilitation. RESULTS: In 187 patients, 346 arms were evaluated. Ninety-four arms (27.1%) were excluded for harvesting. Anatomical abnormalities included size<2 mm (1.5%), diffuse calcifications (8.7%), congenital anomalies (2.3%), and radial artery occlusion (0.3%). Circulatory abnormalities included non-reversal of flow (7.2%), abnormal digital pressures (5.5%), and inappropriate increase in ulnar velocity (1.7%). A total of 116 radial arteries were harvested. There were no episodes of hand ischemia. No patient required hand rehabilitation. CONCLUSIONS Doppler ultrasound and digital plethysmography identifies both perfusion (14.5%) and anatomical (12.7%) abnormalities that may make the radial artery less suitable as a bypass conduit.