Computed tomography of prostatic and bladder rhabdomyosarcomas

Rhabdomyosarcoma represents the most common soft tissue sarcoma in children. The CT findings in five patients with pelvic rhabdomyosarcoma are reported. In the three male patients the primary tumor originated in the prostate gland whereas in the two female patients the bladder was the primary site. The CT findings in the prostatic tumors included an enlarged, inhomogeneous prostatic mass with invasion of the perirectal fat. In two of these patients there was thickening of the levator ani muscle and one showed tumor invasion through the ischiorectal fossa and sciatic and obturator foramina into the pelvic musculature and bone. In the two patients with bladder tumors, one showed a large mass adjacent to the lateral aspect of the bladder and ascites, suggesting an ovarian primary tumor. The other patient with sarcoma botryoides (a subtype of rhabdomyosarcoma) had a diffusely thickened bladder. Two patients have had a follow-up CT demonstrating tumor regression posttherapy. The characteristically large size of these masses and propensity for local invasion in a young patient are typical features of pelvic rhabdomyosarcoma.

Atelectasis and subpulmonic fluid: a CT pitfall in distinguishing pleural from peritoneal fluid

The ability to distinguish between pleural and peritoneal fluid is important in the management of patients with peridiaphragmatic fluid collections. The differentiation of subphrenic fluid from pleural effusion by CT may be difficult and requires a detailed understanding of the normal appearance of the diaphragm on transaxial images. We report 12 patients in whom peridiaphragmatic fluid collections could potentially be misinterpreted as peritoneal rather than pleural fluid. In all cases the presence of subsegmental, basilar atelectasis with subpulmonic fluid created confusing CT images. Subsegmental atelectasis formed a curvilinear band at the lung base that simulated the hemidiaphragm. Fluid anterior to the atelectasis caused a false impression of subdiaphragmatic (peritoneal) fluid. Computed tomography through the upper abdomen excluded intraabdominal fluid in all cases. In four cases ultrasonography confirmed fluid in a supradiaphragmatic, subpulmonic location, excluded peritoneal fluid, and identified subsegmental atelectasis. The presence of subpulmonic fluid and subsegmental atelectasis requires meticulous interpretation of transaxial CT images to avoid the incorrect localization of peridiaphragmatic fluid collections.

CT demonstration of an adrenal pseudocyst

The CT and ultrasound findings in a case of an adrenal pseudocyst are reported. The pathology, etiology, usual manifestations, and differential diagnosis of adrenal cysts are discussed.

Sonography of post-cesarean-section bladder-flap hematoma

A bladder-flap hematoma is an unusual complication of a lower-uterine transverse cesarean section. As a result of bleeding at the incision site, a hematoma forms between the bladder and lower uterine segment. The clinical, sonographic, and surgical findings in seven patients with this complication are described. In all, sonography showed a solid or complex mass of varying sizes interposed between the posterior bladder wall and the anterior uterine wall. Differentiation of a hematoma from an infected hematoma/abscess can be difficult, but the presence of air in the mass strongly suggests the latter. Sonography can detect this complication easily and accurately, and therefore significantly focus and guide therapy.

Human tissue-type plasminogen activator is related to albumin and alpha-fetoprotein

Using a computer program designed to detect evolutionary relationships between proteins, I find that residues 72-110 of the mature sequence of human tissue-type plasminogen activator (t-PA) and 39 residues at the carboxy terminus of human albumin have a comparison score that is 8.8 standard deviation units higher than that obtained with a comparison of randomized sequences of these proteins. The probability (p) of getting this score by chance is approximately 10(-18), indicating that part of t-PA and albumin are derived from a common ancestor. I also find that alpha-fetoprotein, a relative of albumin is related to t-PA. Part of this region on t-PA has been previously shown to be related to epidermal growth factor. t-PA, albumin, alpha-fetoprotein, and epidermal growth factor have diverse biological activities. The finding that these proteins are related suggests some new approaches for studying their functions.

The association of neuroblastoma and myoclonic encephalopathy: an imaging approach

Myoclonic encephalopathy is a unique clinical syndrome of infants and children that is associated with a neurogenic tumor of ganglion-cell origin in approximately half of cases. A review of the literature as well as our personal experience with two recent infants suggests an imaging approach that includes chest radiography and abdominal computed tomography (CT). Ultrasonography, neck CT, and chest CT myelography may be required in selected patients. An expedient clinical and imaging evaluation of infants and children with opsomyoclonus is important to detect those patients with neurogenic tumors.

Gossypol inhibits estrogen binding to rat alpha-fetoprotein

We find that gossypol, a male anti-fertility compound, is a reversible competitive inhibitor of estrogen binding to rat alpha-fetoprotein (AFP). The Kd of gossypol for rat AFP is 1.75 microM, which is similar to gossypol's affinity for lactate dehydrogenase isozyme X, the putative site where gossypol exerts its anti-fertility effects. Reacting sodium cyanoborohydride with gossypol reduces its affinity for AFP, showing that intact aldehyde groups on gossypol are important for binding to rat AFP and indicating that gossypol is specifically inter-acting with a nucleophilic site on AFP that influences estrogen binding.

Amino acid sequence homology between the C3 chain of rat prostatic steroid binding protein and human alpha 2-macroglobulin

Using a computer program designed to detect evolutionary relationships between proteins, I find that exon 2 of the C3 chain of rat prostatic steroid binding protein has amino acid sequence homology with residues 1058-1119 of the protease inhibitor alpha 2-macroglobulin. This finding suggests interesting approaches for studying the functions of these proteins.

Chick oviduct progesterone receptor binding of 15 beta, 17-dihydroxyprogesterone and its analogues

We have tested derivatives of progesterone obtained by fermentation with Aspergillus giganteus for relative binding affinity for the progesterone receptor of chick oviduct. Our studies show that hydroxyl and oxo substitutents at C-11 and C-15 of progesterone significantly decrease the hormone's affinity for the progesterone receptor. The loss in affinity on introduction of a C-15 hydroxyl in 17-hydroxyprogesterone is restored by acetylation to 15 beta-acetoxy-17 hydroxyprogesterone. The latter compound may have some potential as an in vivo agent.

Sperm motility on postcoital testing correlates with male autoimmunity to sperm

To assess whether or not immunologic factors in husbands, wives, or both, influence the motility of sperm in the female reproductive tract, hemagglutination and cytotoxicity sperm antibody (Ab) assays and postcoital tests (PCTs) were performed in 293 infertile couples. More couples without male autoimmunity to sperm (64% of 66; P less than 0.001) had greater than or equal to 10 motile sperm per high power field (adequate PCT), as compared with 26% of 122 couples with untreated male autoimmunity, 19% of 77 couples with corticosteroid-treated male autoimmunity without a pregnancy, and 36% of 28 couples with successfully treated male autoimmunity to sperm. Good correlation was obtained among pregnancy achievement, lack of sperm antibodies, and adequate sperm motility in the PCT (P less than 0.0001). Sperm motility in the PCT correlated positively with sperm motility in the semen and inversely with cytotoxic sperm Ab in the serum and seminal plasma of men and women and hemagglutinating sperm Ab in the cervical mucus samples. Sperm motility in the PCT has a predictive value of 72% for male autoimmunity and 57% for female isoimmunity to sperm in the presence of normal cervical mucus and in the absence of infections.

Diethylpyrocarbonate, a histidine selective reagent, inhibits progestin binding to chick oviduct cytosol

In this report we describe experiments showing that diethylpyrocarbonate, a histidine selective reagent, inhibits progestin binding to the chick oviduct progesterone receptor. Because this inhibition is reversed by hydroxylamine, we suggest that the chick oviduct progesterone receptor contains one or more histidine residues that regulate progestin binding. We also find that the progestin R5020 protects the progesterone receptor from diethylpyrocarbonate mediated inhibition of progestin binding. From this we infer that the progestin binding site contains a histidine residue(s) important for progesterone binding to its receptor in chick oviduct.

Amino acid sequence homology between rat prostatic steroid binding protein and rabbit uteroglobin

Using a computer program designed to detect evolutionary relationships between proteins, I find that the polypeptide chain of rabbit uteroglobin has amino acid sequence homology with the C1 and C2 polypeptide chains of rat prostatic steroid binding protein. Using this finding I suggest several interesting approaches for studying the biology of these proteins.

Inhibition of estrogen binding to rat alpha-fetoprotein by tryptophan p-nitrophenyl esters

Rat alpha-fetoprotein (AFP) contains a site that both binds the protease substrate tryptophan methyl ester (TrpOMe) and influences estrogen binding. We have studied the effect of changing the amino acid and ester portions of this compound on its binding to AFP, as measured by the ability of the ester to inhibit binding of [3H]-estrone to AFP. We find that: (1) AFP binds tryptophan esters better than phenylalanine or tyrosine esters, (2) substitution of butyl or benzyl for the methyl group in TrpOMe increases binding for AFP by 30- to 100-fold, (3) substitution of p-nitrophenol at the ester position increases binding for AFP by 10(5), (4) p-nitrophenyl substitution in the ester position of tyrosine or phenylalanine methyl ester increases the affinity for AFP by 10(3) to 10(4), (5) inhibition of estrogen binding to AFP by tryptophan p-nitrophenyl esters is reversible and competitive, and (6) the hydrolysis products of tryptophan p-nitrophenyl ester are ineffective in inhibiting estrogen binding to AFP. Based on these results, we suggest that AFP contains a tryptophan ester recognition site which binds p-nitrophenyl esters with high affinity and influences estrogen binding. The ester binding site may be located spatially near the estrogen binding site.

Binding of the chymotrypsin substrate, tryptophan methyl ester, by rat alpha-fetoprotein

We studied how tryptophan methyl ester and related compounds inhibit binding of estrone to rat alpha-fetoprotein and find that: (a) like chymotrypsin, alpha-fetoprotein binds tryptophan esters with higher affinity than tryptophan or its amides; (b) the affinity of alpha-fetoprotein for tryptophan methyl ester is 3.7 . 10(-4) M, which is close to the affinity of chymotrypsin (10(-4) M); (c) alpha-fetoprotein binding of tryptophan methyl ester is stereoselective and pH dependent. All of these observations suggest that there is a specific interaction between alpha-fetoprotein and the chymotrypsin substrate, tryptophan methyl ester, and that rat alpha-fetoprotein contains a site with some structural similarities to the catalytic site in chymotrypsin. Since we also find that tryptophan methyl ester is a competitive inhibitor of estrone binding to alpha-fetoprotein, it is possible that the protease substrate binding site on alpha-fetoprotein is spatially close to the estrone binding site.

Inhibition by protease inhibitors of binding of adrenal and sex steroid hormones

Binding of steroid hormones is inhibited by protease inhibitors and substrates. The protease inhibitors phenylmethyl sulphonylfluoride, tosyl-lysine chloromethyl ketone, and tosylamide-phenylethyl-chloromethyl ketone and the protease substrates tosyl arginine methyl ester and tryptophan methyl ester eliminate specific binding of aldosterone, dexamethasone, dihydrotestosterone, estrogen, and progesterone to their respective receptors. These protease inhibitors and substrates also inhibit binding of progesterone to the 20,000 molecular weight mero-receptor formed from the progesterone receptor in chick oviduct. The binding of estradiol to rat alpha-fetoprotein is inhibited by the protease inhibitors and substrates but not by tryptophan or tryptophan amide, indicating the importance of an ester structure in the inhibition of steroid binding. Our results suggest that all steroid hormone receptors have a site with both common structural features and a role in the regulation of steroid hormone binding.