Licorice and enzymes other than 11 beta-hydroxysteroid dehydrogenase: an evolutionary perspective

Licorice has long been known to promote the healing of ulcers. In the 1950s, studies with licorice-derived compounds revealed that the anti-ulcer effects of licorice are due to inhibition of 15-hydroxyprostaglandin dehydrogenase and delta 13-prostaglandin reductase. 15-Hydroxyprostaglandin dehydrogenase converts prostaglandins E2 and F2 alpha to 15-ketoprostaglandins, which are inactive. delta 13-Prostaglandin reductase metabolizes the inactive delta 13-prostaglandin to 13,14-dihydro,15-ketoprostaglandin, which is further metabolized and excreted in urine. Thus, licorice-derived compounds have the effect of raising the local concentration of prostaglandins that promote mucous secretion and cell proliferation in the stomach, leading to healing of ulcers. 11 beta-Hydroxysteroid dehydrogenase, which also is inhibited by licorice-derived compounds, shares a common ancestor with 15-hydroxyprostaglandin dehydrogenase. Both enzymes are homologous to Streptomyces hydrogenans 3 alpha,20 beta-hydroxysteroid dehydrogenase, which also is inhibited by licorice. Thus, licorice inhibits enzymes that diverged at least 2 billion years ago from a common ancestor. Other oxidoreductases in bacteria, plants, and animals that are inhibited by licorice-derived compounds are likely to be discovered in the future.

Chicken sterol carrier protein 2/sterol carrier protein x: cDNA cloning reveals evolutionary conservation of structure and regulated expression

The chicken is a useful model for studies of lipid biochemistry because of the profound changes in lipid metabolism during development and the marked effects of estrogen on its lipids. Here we report the cloning of a cDNA encoding chicken sterol carrier protein 2 (SCP2)/sterol carrier protein x (SCPx), proteins that are believed to play key roles in intracellular lipid movement and metabolism. The 2.4-kb clone, isolated from a liver cDNA library by homology screening with a rat SCP2 cDNA, encodes a 58-kDa polypeptide, SCPx, which encompasses the sequence for SCP2 at its C-terminus. Comparison of the deduced amino acid sequence of the chicken protein with those of mammals revealed conservation of structure from an evolutionary standpoint. Like the other vertebrate SCPx proteins, the chicken protein contains a conserved Arg-Gly-Asp sequence and a cysteine residue in the N-terminus that aligns with the active site cysteine of Escherichia coli 3-ketoacyl-CoA thiolase, a protein that was previously shown to be homologous to vertebrate SCPx. Northern blot analysis of poly(A)+ RNA from different chicken tissues revealed two mRNA species, one of 2.5 kb, encoding SCPx, and one of 1.4 kb, presumably encoding SCP2. High levels of the 2.5 and 1.4-kb mRNAs were found in liver, intestine, and ovarian granulosa cells, consistent with a role for these proteins in lipid metabolism. There was no change in the 2.5-kb mRNA in chicken liver with development (Day 20 embryo to 4 weeks posthatch), but there was a 10-fold increase in the 1.4-kb mRNA by 1 week posthatch. Treatment of roosters with a single injection of estradiol (25 mg/kg) caused a twofold increase in the 2.5-kb mRNA in liver at 6 h after estradiol administration, reaching a maximum fourfold increase at 48 h, while the 1.4-kb mRNA increased twofold at 48 h. The two SCP2/SCPx mRNAs were most abundant in granulosa cells from small follicles. A reduction in SCP2/SCPx gene expression was observed with follicular maturation, correlating with falling estrogen production. In summary, we have documented (i) marked conservation of SCP2/SCPx structure across species and (ii) developmental and hormonal regulation of the mRNAs which encode proteins thought to be involved in lipid metabolism.

Focal fatty infiltration: a cause of nontumorous defects in the left hepatic lobe during CT arterial portography

OBJECTIVE

The purpose of this work was to determine the frequency and significance of characteristic nontumorous low attenuation defects found in the left hepatic lobe during CT arterial portography (CTAP).

MATERIALS AND METHODS

Eighty CTAPs performed over a 17 month period were retrospectively reviewed to identify nonsegmental low attenuation defects adjacent to the falciform ligament, gallbladder, or porta hepatis. Twenty-four separate defects were present in 14 of 80 (18%) patients. Cases in which a defect was present were compared with MR, surgical findings, and pathology reports.

RESULTS

The defects were oval or triangular in shape with a mean maximum diameter of 1.7 cm (range 1-5 cm). None of these defects were identified on MR in the 12 patients who underwent T1, T2, and STIR MR; however, 3 showed dropout of signal on chemical shift MR, suggesting fatty infiltration. In the 12 patients who underwent surgery, no lesion was shown to represent tumor. Two intraoperative biopsies of the area of the defects showed fatty infiltration.

CONCLUSION

Nontumorous low attenuation defects adjacent to the gallbladder, falciform ligament, or porta hepatis are a pitfall of CTAP and can be associated with focal fatty infiltration, as well as decreased perfusion due to technical factors or a variation in hepatic vascular supply.

Aldosterone stimulated differentiation of mouse 3T3-L1 cells into adipocytes

We find that 1-10 nM aldosterone can induce differentiation of 3T3-L1 cells into adipose cells as evaluated by microscopic accumulation of fat droplets and quantitative measurement of triglycerides and of glycerol-3-phosphate dehydrogenase, an enzyme specific for adipocyte differentiation. Moreover, the aldosterone antagonist ZK91587 inhibits aldosterone-but not glucocorticoid-mediated differentiation of 3T3-L1 cells. Steroid binding assays with 3T3-L1 cells indicate the presence of specific binding sites for aldosterone. We conclude that there is an aldosterone receptor-mediated pathway for terminal differentiation of 3T3-L1 cells into adipose cells. Receptors for aldosterone have also been found in a variety of cells that do not function to regulate sodium and potassium transport. The aldosterone receptor may have a role in regulation expression of genes involved in differentiation of these cells.

Inhibition of 3,5,3'-triiodothyronine binding to its receptor in rat liver by protease inhibitors and substrates

Various protease inhibitors (e.g. phenylmethanesulfonyl fluoride (PMSF), tosyl-phenylalanine chloromethyl ketone (TosPheCH2Cl)) and substrates (e.g., tosyl-arginine methyl ester (TosArgOMe), tryptophan methyl ester (TrpOMe)) inhibit the binding of adrenal and sex steroids to their cognate receptors (Hubbard and Kalimi (1985) Mol. Cell. Biochem. 66, 101-109). Here we extend this finding to the receptor for 3,5,3'-triiodothyronine (T3) in rat liver nuclei. We find that PMSF, TosPheCH2Cl and other protease inhibitors as well as TosArgOMe, TrpOMe, tyrosine methyl ester (TyrOMe) and tyrosine ethyl ester (TyrOEt) inhibit binding of 125I-T3 to its receptor in rat liver nuclei. Inhibition by protease substrates appears to be at or close to the hormone binding domain. By analogy with the known mechanism of binding of protease inhibitors and substrates to enzymes, we suggest that the T3 receptor contains a nucleophilic site at or close to the hormone binding domain.

Site-specific mutagenesis of Drosophila alcohol dehydrogenase: evidence for involvement of tyrosine-152 and lysine-156 in catalysis

Amino acid sequence comparisons reveal that tyrosine-152 and lysine-156 of Drosophila alcohol dehydrogenase (ADH) are conserved in homologous dehydrogenases, suggesting that these residues are important in catalysis. To test this hypothesis, we used site-directed mutagenesis to substitute tyrosine-152 with phenylalanine, histidine, or glutamic acid or to substitute lysine-156 with isoleucine. All of these mutants are catalytically inactive. Two mutants were active: A cysteine mutation of tyrosine-152 has 0.25% of wild-type ADH activity, while an arginine substitution of lysine-156 retains 2.2% of wild-type ADH activity. Kinetic analysis shows that the cysteine mutant increases Km(ethanol) 56-fold and Km(propan-2-ol) 100-fold, while Km(NAD) values are essentially unaltered. The arginine mutant also shows the significant enlargement of Km(ethanol), but not of Km(NAD). Furthermore, the cysteine mutant and arginine mutant have different substrate specificity and behave differently on competitive inhibition than wild-type ADH. These results suggest that both tyrosine-152 and lysine-156 have essential roles in catalysis by Drosophila ADH.

Contrast material for combined abdominal and pelvic CT: can cost be reduced by increasing the concentration and decreasing the volume?

OBJECTIVE

The purpose of this study was to determine if enhancement provided by a smaller volume of a more concentrated nonionic contrast agent is equivalent to that provided by a larger volume of a less concentrated nonionic agent on dynamic, incremental abdominal and pelvic CT.

SUBJECTS AND METHODS

During a 4-month period, 168 patients undergoing dynamic incremental abdominal and pelvic CT received 150 ml iopamidol-300 (45 g iodine). During the following 4 months, 119 patients received 125 ml ioversol-320 (40 g iodine). The same automated injector and scanning parameters were used for both groups. Absolute enhancement of the liver at three levels and of abdominal and pelvic vessels was calculated and analyzed by using Student's t-test.

RESULTS

Arterial and venous enhancement in the upper part of the abdomen, at the level of the iliac crest, or in the pelvis was not significantly different with the two contrast agents. Both ioversol and iopamidol provided the same mean enhancement of the hepatic parenchyma at the level of the hepatic veins (45 H) and at the level of the portal vein (49 H). At the level of the gallbladder fossa, enhancement of liver parenchyma with the two contrast agents was significantly different (p = .04): mean enhancement was 45 H for iopamidol and 42 H for ioversol. A retrospective analysis of the liver enhancement profiles from 50 randomly selected patients from each group showed no significant difference in parenchymal enhancement.

CONCLUSION

For dynamic abdominal and pelvic CT, no statistically significant difference was found between the mean enhancement of the liver and abdominal vessels after administration of 125 ml of ioversol-320 and that after administration of 150 ml of iopamidol-300. Therefore, 125 ml of ioversol-320 can be used instead of 150 ml of iopamidol-300 without compromising image quality. At current prices, this will result in savings of approximately 18% per patient.

Appearance of oxidized cellulose (Surgicel) on postoperative CT scans: similarity to postoperative abscess

OBJECTIVE

Oxidized regenerated cellulose (Surgicel), a sterile knitted fabric that causes thrombus formation because of its physical properties, is frequently used for intraoperative hemostasis. Unlike traditional surgical sponges, it is bioabsorbable and can be left in the surgical bed. On CT scans, the appearance of the retained oxidized cellulose can mimic that of an abscess. The purpose of this study was to describe the appearance of oxidized regenerated cellulose on postoperative CT scans so that an erroneous diagnosis of an abscess can be avoided.

MATERIALS AND METHODS

We reviewed the CT examinations of five postoperative patients in whom oxidized regenerated cellulose had been used for surgical hemostasis. Operative reports and surgeons confirmed the use of oxidized cellulose. Four CT scans were abdominal examinations, and one was a head examination.

RESULTS

In four cases, CT scans showed focal, linear collections of gas within masses with mixed attenuation in or near the operative site. No air-fluid levels were present. In three patients, cultures of specimens obtained by aspiration were negative for pyogenic organisms.

CONCLUSION

Retained oxidized cellulose can mimic an abscess on CT scans. Focal collections of air centrally located within a mass should alert the radiologist that oxidized cellulose may have been placed in the operative site, and an appropriate history should be sought.

Effect of brassinolide on gene expression in elongating soybean epicotyls

We have studied the effect of brassinolide (BR), a plant steroidal lactone, on the expression of auxin-regulated genes in soybean (Glycine max L. cv Williams 82) epicotyls. BR caused up to 4-fold increases in epicotyl length during extended assays at 10(-7)m, in the absence of added auxin. Structurally related steroids failed to induce elongation or to alter the BR effect. Northern blot analysis, using sequences corresponding to auxin-regulated genes as probes, has shown that the molecular mechanism of BR-induced elongation is likely to differ from that of auxin-induced elongation in this system. BR does not rapidly induce members of the GH, SAUR, or JCW auxin-inducible gene families before the onset of elongation. BR enhances SAUR and GH1 transcripts after 18 h but has no effect on JCW1 or GH3 transcripts at any time examined. We have shown by two-dimensional gel analysis of in vitro translated mRNA that a submicromolar concentration of BR alters the pattern of gene expression in elongating soybean epicotyls.

Effect of brassinolide on gene expression in elongating soybean epicotyls

We have studied the effect of brassinolide (BR), a plant steroidal lactone, on the expression of auxin-regulated genes in soybean (Glycine max L. cv Williams 82) epicotyls. BR caused up to 4-fold increases in epicotyl length during extended assays at 10(-7)m, in the absence of added auxin. Structurally related steroids failed to induce elongation or to alter the BR effect. Northern blot analysis, using sequences corresponding to auxin-regulated genes as probes, has shown that the molecular mechanism of BR-induced elongation is likely to differ from that of auxin-induced elongation in this system. BR does not rapidly induce members of the GH, SAUR, or JCW auxin-inducible gene families before the onset of elongation. BR enhances SAUR and GH1 transcripts after 18 h but has no effect on JCW1 or GH3 transcripts at any time examined. We have shown by two-dimensional gel analysis of in vitro translated mRNA that a submicromolar concentration of BR alters the pattern of gene expression in elongating soybean epicotyls.

Stent placement for benign pancreatic diseases: correlation between ERCP findings and clinical response

OBJECTIVE

We performed a study to determine if the appearance of the pancreatic duct on ERCP before and after placement of pancreatic duct stents correlates with the therapeutic response in patients treated for impaired pancreatic drainage.

MATERIALS AND METHODS

Findings in 29 consecutive patients with a variety of benign pancreatic diseases in whom pancreatic stents were placed and subsequently removed within a 3-year period were reviewed retrospectively. Early (1-5 days) and late (1-3 months) clinical outcomes after stent placement were assessed. These findings were correlated with a blinded interpretation of ERCP findings (Cambridge criteria were used) before and after stent placement.

RESULTS

ERCP findings before stent placement were normal in 10 patients. At the end of stent therapy, ERCP showed changes associated with chronic pancreatitis in all 10; five had focal narrowing at the tip of the stent. Subsequent ERCP studies in five of these 10 patients showed that ductal changes induced by stents diminished after stent removal. Of the 19 patients with abnormal findings on ERCP at the time of stent placement, ERCP at the end of stent therapy showed some improvement in seven patients, no change in eight, and deterioration in four. Changes seen on ERCP had no statistically significant correlation with clinical outcome (p = .36).

CONCLUSION

Our findings show that pancreatic duct stents can induce abnormalities on ERCP indicative of chronic pancreatitis. However, diminution of these abnormalities after stent removal in some patients suggests that these changes may be due to edema rather than to fibrosis. Ductal changes seen on ERCP are not a useful guide for determining the degree of response to pancreatic stents.

CT arterial portography: causes of technical failure and variable liver enhancement

OBJECTIVE

We studied the causes of technical failure and enhancement variability encountered during CT arterial portography.

MATERIALS AND METHODS

CT arterial portograms and digital arteriograms were obtained via the superior mesenteric artery before partial liver resection in 43 patients with malignant tumors. These studies were reviewed for causes of technical failure and variable enhancement.

RESULTS

Eleven (26%) of 43 procedures were technical failures. Causes of failure included aortic injection after catheter dislodgement (four), dense hyperenhancement associated with laminar flow in the portal vein produced by rapid venous return from a selective injection into a proximal branch vessel of the superior mesenteric artery (two), premature scanning beginning at the iliac crest (two), reflux into a replaced right hepatic artery (one), hepatic arterial enhancement via the pancreaticoduodenal arcade (one), and portal hypertension (one). Of the 32 remaining studies, 28 showed areas of parenchymal hypoenhancement or hyperenhancement. Causes of variable enhancement included impaired portal vein perfusion from mass effect of the tumor, laminar flow in the portal vein, and focal fatty infiltration.

CONCLUSION

Technical failures and enhancement variability are common in CT arterial portography. Factors leading to technical failure include catheter choice and position, portal hypertension, and operator error.

Inhibition of Streptomyces hydrogenans 3 alpha,20 beta-hydroxysteroid dehydrogenase by licorice-derived compounds and crystallization of an enzyme-cofactor-inhibitor complex

Streptomyces hydrogenans 3 alpha,20 beta-hydroxysteroid dehydrogenase reduces the C20 ketone on glucocorticoids and progestins. We find that two licorice-derived compounds, glycyrrhizic acid and carbenoxolone, inhibit this enzyme with microM Kis. Inhibition is competitive, indicating that these compounds are binding at or close to the catalytic site. Carbenoxolone's high aqueous solubility and affinity for 3 alpha,20 beta-hydroxysteroid dehydrogenase enabled us to prepare crystals of a carbenoxolone-NADH-enzyme ternary complex, which preliminary X-ray analysis indicates has a crystal structure that is significantly different from that of the 3 alpha,20 beta-hydroxysteroid dehydrogenase-NADH complex. A comparison of the tertiary structures of these two complexes should prove useful in understanding this enzyme's catalytic mechanism, as well as those of two homologous enzymes, mammalian 11 beta-hydroxysteroid dehydrogenase and 15-hydroxyprostaglandin dehydrogenase that also are inhibited by carbenoxolone.

Malignant biliary obstruction: efficacy of thin-section dynamic CT in determining resectability

OBJECTIVE

Several authorities advocate the use of preoperative angiography to determine the resectability of pancreatic and periampullary tumors, claiming that CT alone is not sufficiently accurate for this purpose. Our objective was to assess the value of CT in predicting surgical resectability in patients with malignant biliary obstruction.

MATERIALS AND METHODS

We performed a retrospective analysis of 380 consecutive cases of malignant biliary obstruction spanning a 4-year period. Most patients (230) were treated nonoperatively. Sixty-seven patients had surgery, pathologic confirmation of malignancy, and preoperative CT scans available for review. The CT scans were assessed for surgical resectability of tumor by an interpreter who did not know the patient's history.

RESULTS

Forty-two patients had pancreatic adenocarcinoma, six had ampullary carcinoma, seven had cholangiocarcinoma, and 12 had other malignant neoplasms. Of 47 patients with tumors thought to be unresectable on the basis of CT findings, 42 had tumors that were found to be unresectable at surgery (positive predictive value, 89%). Of 20 patients with tumors thought to be resectable, 16 had tumors that were surgically resectable (positive predictive value, 80%). CT did not show metastases to duodenal lymph nodes (n = 2), portal vein infiltration (n = 1), and small hepatic metastases (n = 1). Visualization of most of these at angiography would not be expected. The CT finding of infiltration of the periarterial fat around the celiac or superior mesenteric arteries was reliable for predicting surgical unresectability. Lymphadenopathy and infiltration of nonperivascular fat planes were less reliable predictors of unresectability.

CONCLUSION

Although some findings on CT that suggest unresectability are less reliable than others, the accuracy of CT compares favorably with reports on the accuracy of angiography for assessing tumor resectability in cases of malignant biliary obstruction. The addition of angiography to the examination of patients with potentially resectable lesions is not justified when high-quality, thin-section dynamic CT has been performed.

Effect of protease inhibitors and substrates on 3,5,3'-triiodothyronine binding to rat liver nuclear receptors

The effect of protease inhibitors N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) and N-carbobenzoxy-L-phenylalanine chloromethyl ketone (ZPCK) at concentrations ranging from 1.5 x 10(-6) mol/l to 1.5 x 10(-4) mol/l on the specific binding of 3,5,3'-triiodothyronine (T3) to rat liver nuclear receptors was evaluated. Both TPCK at 1.5 x 10(-5) mol/l (P < 0.001) and ZPCK at 1.5 x 10(-6) mol/l (P < 0.05) showed the inhibition of T3 binding to nuclear receptors. The evaluation of T3 binding data following separation of unbound TPCK from treated nuclear receptors on a Sephadex G-25 column showed that the inhibition of T3 binding was irreversible, since a substantial decrease of the equilibrium association constant (Ka) was found when compared to the mock samples lacking TPCK. In addition, similar inhibitory effect on T3 specific binding to rat liver nuclear receptors was found at 5.0 x 10(-4) mol/l by protease substrates L-tyrosine benzyl ester (P < 0.001), L-tyrosine ethyl ester (P < 0.02), L-tryptophan methyl ester (P < 0.02) and L-tryptophan ethyl ester (P < 0.05). The data suggest that: 1. both protease inhibitors and substrates tested inhibited T3 specific binding to T3 nuclear receptors; 2. this may support the hypothesis that T3 receptors like other receptors encoded by c-erbA gene possess a site that recognize both serine protease inhibitors and substrates in its hormone binding domain.

Progestins stimulate the differentiation of 3T3-L1 preadipocytes

The effect of progesterone on the differentiation of the 3T3-L1 preadipocytes was investigated and compared with other sex steroids (estradiol and testosterone), with cortisol, with the synthetic progestin R5020 and with the progestin/glucocorticoid antagonist RU38486. At 10(-8) M, progesterone stimulated the activity of glycerol-3-phosphate dehydrogenase and triglyceride deposition. Progesterone, R5020, cortisol, and RU38486 increased triglycerides about 2-fold at 10(-7) M. Only minimal effects were observed with testosterone and estradiol even at 10(-6) M. When the cells were cultured in presence of 10(-5) M metyrapone the effect of progesterone was unchanged, suggesting that the progesterone was not metabolized to a glucocorticoid. Progesterone, R5020 and RU38486 competed efficiently with [3H]dexamethasone for the glucocorticoid receptor in 3T3-L1 cytosol. These results indicate a significant, reproducible dose-dependent effect of progestins on differentiation of the preadipocytes, which appears to be mediated via the glucocorticoid receptor.

Membrane transport proteins: implications of sequence comparisons

Analyses of the sequences and structures of many transport proteins that differ in substrate specificity, direction of transport and mechanism of transport suggest that they form a family of related proteins. Their sequence similarities imply a common mechanism of action. This hypothesis provides an objective basis for examining their mechanisms of action and relationships to other transporters.

Similarities between legume-rhizobium communication and steroid-mediated intercellular communication in vertebrates

Regulation of the actions of flavonoids and Nod factors in legume-rhizobia communication has several interesting similarities with that of steroid-mediated actions in vertebrates. Oxidation or reduction of flavonoids and Nod factors modifies their biological activity just as, for example, oxidation of an alcohol at C11 on hydrocortisone regulates its biological activity. Second, some flavonoids are anti-inducers, functioning like steroid antagonists to negate the actions of inducer flavonoids. Amino acid sequence analyses show that human 17 beta-hydroxysteroid dehydrogenase, which catalyzes the interconversion of the alcohol and ketone at C17 on estrogens and androgens, and rat 11 beta-hydroxysteroid dehydrogenase, which catalyzes the interconversion of the alcohol and ketone at C11 of glucocorticoids, and Rhizobium meliloti NodG and Bradyrhizobium japonicum. FixR are derived from a common ancestor. Just as steroid-metabolizing enzymes can regulate steroid-mediated gene transcription, enzymes that modify substituents on flavonoids and Nod factors may have a similar role in regulating signalling between legumes and rhizobia. The enzymes that modify flavonoids and Nod factors have not yet been identified. However, NodG and FixR are two likely candidates to have this role in regulating legume-rhizobia signalling.

Expansion of the mammalian 3 beta-hydroxysteroid dehydrogenase/plant dihydroflavonol reductase superfamily to include a bacterial cholesterol dehydrogenase, a bacterial UDP-galactose-4-epimerase, and open reading frames in vaccinia virus and fish lymphocystis disease virus

Mammalian 3 beta-hydroxysteroid dehydrogenase and plant dihydroflavonol reductases are descended from a common ancestor. Here we present evidence that Nocardia cholesterol dehydrogenase, E. coli UDP-galactose-4 epimerase, and open reading frames in vaccinia virus and fish lymphocystis disease virus are homologous to 3 beta-hydroxysteroid dehydrogenase and dihydroflavonol reductase. Analysis of a multiple alignment of these sequences indicates that viral ORFs are most closely related to the mammalian 3 beta-hydroxysteroid dehydrogenases. The ancestral protein of this superfamily is likely to be one that metabolized sugar nucleotides. The sequence similarity between 3 beta-hydroxysteroid dehydrogenase and the viral ORFs is sufficient to suggest that these ORFs have an activity that is similar to 3 beta-hydroxysteroid dehydrogenase or cholesterol dehydrogenase, although the putative substrates are not yet known.

Subxiphoid pericardiotomy in the diagnosis and management of large pericardial effusions associated with malignancy

To determine the safety, diagnostic value, and clinical outcome of patients with malignancy undergoing subxiphoid pericardiotomy for large pericardial effusions, we prospectively studied 25 consecutive patients with malignancy and new, large pericardial effusions diagnosed by echocardiography. Twenty-two of the 25 operations were done under local anesthesia, and no patient died at surgery. Pericardial fluid cytology revealed malignant cells in 11 patients (44 percent), while tumor was seen in only five (45 percent) of these 11 patients on pathologic examination. The remaining 14 patients showed no evidence of pericardial invasion with tumor. Evidence of intrathoracic disease by CT or MRI scanning, tamponade, a sanguineous pericardial fluid character, and an elevated serum and pericardial fluid lactate dehydrogenase level all were suggestive of malignant invasion of the pericardium. All 25 patients were followed at least 12 months postoperatively. Effusions recurred in three patients (12 percent), and one patient required reoperation. Overall mortality was 72 percent with a 91 percent (10 of 11) mortality for those with malignant effusions and a 57 percent (8 of 14) mortality for those with nonmalignant effusions. Diagnostically, subxiphoid pericardiotomy has little advantage over examination of pericardial fluid alone in this group of patients. Therapeutically, however, it is a low morbidity procedure which is safe and effective in treating patients with malignancy and large pericardial effusions.

Sex hormone-binding globulin, androgen-binding protein, and vitamin K-dependent protein S are homologous to laminin A, merosin, and Drosophila crumbs protein

Androgen-binding protein (ABP) and sex hormone-binding globulin (SHBG) are extracellular steroid-binding proteins that are homologous to the COOH-terminal domain of vitamin K-dependent protein S, a protein important in blood clotting. We find that the sequences of ABP, SHBG, and protein S are also similar to two basement membrane proteins, laminin and merosin, and to an integral membrane protein, Drosophila crumbs protein. These latter three proteins have important roles in regulating differentiation and development. The sequence similarity corresponds to the G domain of laminin A chain, which binds heparin and type IV collagen. Analysis of a multiple alignment of these proteins reveals one well-conserved segment corresponding to the part of SHBG that binds to its membrane receptor and another corresponding to the part of protein S that binds to C4b-binding protein. The similarities suggest that ABP, SHBG, and protein S may also have functions related to that of laminin and merosin.