Tumor vascular signals in renal masses: detection with Doppler US

The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses.     

Conformational preference for the binding of biaryl substrates and inhibitors to the active site of phenylethanolamine N-methyltransferase

We have previously described regions of steric bulk tolerance in the aromatic-ring binding site of phenylethanolamine N-methyltransferase (PNMT, EC 2.1.1.28) for phenylethanolamine substrates and alpha-methylbenzylamine inhibitors. For bound substrates, this region is located in the vicinity of the para position of the aromatic ring, while for bound alpha-methylbenzylamine inhibitors, it is located in the region complementary to the meta position. In the present study, we sought to determine the preferred conformation of the biaryl portion of (m-phenylphenyl)- and (p-phenylphenyl)ethanolamine (4 and 5, respectively) as well as for m-phenyl- and p-phenyl-alpha-methylbenzylamine (7 and 8, respectively) for PNMT active site interactions. Planar derivatives of 4, 5, 7, and 8 were obtained through the synthesis of 2-(1-fluorenyl)-2-hydroxyethylamine (9), 2-(2-fluorenyl)-2-hydroxyethylamine (10), 1-(1-fluorenyl)ethylamine (11), and 1-(2-fluorenyl)ethylamine (12). The four fluorene derivatives were examined for in vitro activity as substrates and inhibitors of the PNMT-catalyzed reaction. As in the case of 4, 5, 7, and 8, we have observed a positional preference for the alkylamine side chain with respect to the biphenyl skeleton present in 9-12. Thus, fluorenylethanolamine 10 ("p-biphenyl") displays a Michaelis constant (Km = 26 microM) that is approximately 10 times lower than that for 9 ("m-biphenyl", Km = 297 microM); in the alpha-methylbenzylamine inhibitors, fluorenyl derivative 11 ("m-biphenyl", Ki = 4.14 microM) is approximately 40 times better than 12 ("p-biphenyl", Ki = 185 microM) for in vitro inhibition of PNMT. In each case, conformational restriction of the biaryl system present in 4, 5, 7, and 8, such that the aromatic rings are coplanar, resulted in enhanced affinity for the PNMT active site. Thus, conformational restriction of ethanolamine 5 (Km = 82 microM) as in 10 (Km = 26 microM) and alpha-methylbenzylamine 7 (Ki = 89 microM) as in 11 (Ki = 4.14 microM) leads, in each case, to a stronger enzyme-ligand dissociable complex. These results, in conjunction with others from these laboratories, indicate that the PNMT active site beyond the zone that interacts with the central aromatic ring portion of phenylethanolamine substrates and alpha-methylbenzylamine inhibitors is essentially a flat, hydrophobic pocket.     

Amount and distribution of dietary protein affects clinical response to levodopa in Parkinson's disease

Reducing dietary protein improves the effectiveness of levodopa (LD) but the most effective distribution of a low-protein diet (0.8 g/kg) is unclear. We compared a 1.6 g/kg protein diet, a 0.8 g/kg diet with protein evenly distributed between meals, and a 0.8 g/kg diet with protein restricted to the evening meal in 5 parkinsonian patients with motor fluctuations. We monitored clinical response, plasma LD, and plasma large amino acids (LNAAs) hourly throughout the day. Mean "on" times were 51% (1.6 g/kg diet), 67% (0.8 g/kg evenly distributed), and 77% (0.8 g/kg restricted). Hourly averages of plasma LD did not differ between the diets. The mean plasma LNAAs were 732 nmol/ml (1.6 g/kg diet), 640 (0.8 g/kg distributed), and 542 (0.8 g/kg restricted), and the diurnal pattern reflected the distribution of protein intake. In conclusion, the amount and distribution of dietary protein affect clinical response to LD. These effects are not related to LD absorption but are explained by the variation in plasma LNAAs.     

Image-directed percutaneous biopsies with a biopsy gun

Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.     

Polymorphisms of the equine major histocompatibility complex class II DRA locus

The full extent of the polymorphism of ELA-DRA in Equidae is not yet known. Given the apparent differences in DRA polymorphisms between Equidae and other species, the aims of this study were to more fully characterize ELA-DRA, determine the extent of gene polymorphism and establish the allele-frequency distribution. An allele reference panel for the second exon of ELA-DRA was established by sequence-based typing of 69 equine DNA samples consisting of various breeds of domestic horse (Equus caballus), together with donkeys (Equus asinus), Grant's zebras (Equus boehmi) and one onager (Equus hemionus). Five of the six previously reported alleles detected using single-strand conformation polymorphism were found: ELA-DRA*0101, ELA-DRA*0201, ELA-DRA*0301, ELA-DRA*0501 (Albright-Fraser DG et al. Polymorphism of DRA among equids. Immunogenetics 1996: 43: 315-7) and ELA-DRA*0601 (GenBank accession number AF5419361). In addition to the previously reported alleles, five novel ELA-DRA alleles were detected within the ELA-DRA allele reference panel. One of these was identified in E. caballus (ELA-DRA*JBH11), one in E. boehmi and E. hemionus (ELA-DRA*JBZ185) and three in E. asinus (ELA-DRA*JBD3, ELA-DRA*JBD17 and ELA-DRA*JBH45). A total of 565 equine DNA samples were screened using reference-strand-mediated conformation analysis, a double-stranded conformation-based mutation detection system that can be used to type existing ELA-DRA alleles and identify new variants. Based on our findings, at least 11 ELA-DRA alleles are now known to exist, and this level of polymorphism at the DRA locus appears to be unique to the genus Equus. Both the previously reported alleles and the new alleles displayed a species-specific distribution.     

Early diagnosis of relapse in acute myeloblastic leukemia: Serologic detection of leukemia-associated antigens in human marrow.

We tested serial bone-marrow samples from 47 adults with acute myeloblastic leukemia in remission for reactivity with heteroantiserums to leukemia-associated antigens, to determine whether imminent relapse could be detected in patients with acute leukemia. Of 26 patients who relapsed by standard morphologic criteria, 21 had increased immunoreactivity of bone marrow for one to six months (mean, 3.7 months) before relapse. High concordance was observed between a positive test and relapse during the period of study (chi-square = 27.53, P less than 0.001). The median time to relapse after a positive test was four months, as compared with the median remission duration of 19 months for the whole group (P less than 0.02, Peto's log-rank analysis). Serologic detection of leukemia-associated antigens in marrow may be a reliable indicator of imminent relapse in acute myeloblastic leukemia.     

Isolation of the etiologic agent of human granulocytic ehrlichiosis from the white-footed mouse (Peromyscus leucopus)

We examined white-footed mice (Peromyscus leucopus) from Minnesota for infection with the etiologic agent of human granulocytic ehrlichiosis (HGE). From April to September 1997, we collected P. leucopus from Washington County, Minnesota, an area enzootic for HGE. Blood was cultivated in HL60 cells for isolation of the HGE agent. Of 59 mice examined, only a single mouse was culture positive for the HGE agent. The 16S ribosomal DNA sequence of the isolate was determined to be identical to that of the HGE agent. The isolate was reactive with monoclonal antibodies to the 44-kDa antigen of the HGE agent and was infectious for laboratory mice.