Regional changes of NADPH-diaphorase and neuropeptide Y neurons in the cerebral cortex of aged Fischer 344 rats

This study examined the effects of aging on neuropeptide Y (NPY) and NADPH-diaphorase (NADPH-d)-positive neurons of the cerebral cortex in young (3 months) and aged (24 months) Fischer 344 rats by immunohistochemical and histochemical methods. In the aged group, the number of NPY-immunoreactive (IR)/NADPH-d-positive neurons was not significantly changed in all regions of the cerebral cortex compared to the control group. However, the number of NPY-IR/NADPH-d-negative neurons was significantly decreased in frontal association, primary motor, secondary somatosensory, insular, ectorhinal, perirhinal and auditory cortex in the aged group. In the aged rats, about 5-10% of NPY-IR/NADPH-d-positive neurons were dystrophic and scattered within the cerebral cortex. These results suggested that NPY-IR neurons that do not contain NADPH-d are affected by aging and that aging influences NPY-IR/NADPH-d-negative neurons in a region-specific pattern within the cerebral cortex of rats.

The binding site of a specific aminoglycoside binding RNA molecule

A small (40 nucleotides) stem-loop derivative (J6f1) of a specific aminoglycoside-binding RNA aptamer, containing a 3 nt and a 1 nt bulge, has previously been shown to stoichiometrically bind tobramycin with a dissociation constant of approximately 5 nM [Hamasaki, K., Killian, J., Cho, J. and Rando, R. R. (1997) Biochemistry 36, 1367-1371]. This construct can strongly discriminate among similar aminoglycosides with respect to binding. A combination of chemical interference studies, chemical modification studies, and mutational studies are performed to define the aminoglycoside binding site of J6f1. Recognition of the aminoglycoside by J6f1 involves contacts with nucleotide bases, rather than with the phosphate backbone. The binding site 1 comprised of part of the stem-loop region. The two bulges are also essential for high affinity and stoichiometric binding of tobramycin. These bulges are probably important for prying open the double helical region, thereby allowing the aminoglycoside access to the nucleotide bases.

Pharmacodynamics of topoisomerase I inhibition: Western blot determination of topoisomerase I and cleavable complex in patients with upper gastrointestinal malignancies treated with topotecan

Analogues of camptothecins are specific inhibitors of eukaryotic DNA topoisomerase I (topo I) that lead to DNA damage and, eventually, cellular cytotoxicity. Camptothecin analogues bind to this target enzyme in the course of its normal function and stabilize the DNA-enzyme adduct to form a "cleavable complex." Preclinical experiments using Western blot analyses have shown cleavable complex formation to be the key intermediate step in topo I inhibition. In this series of experiments, it was our goal to convert this laboratory technique into a useful clinical assay, allowing measurement of the target enzyme and detection of the key intermediate in clinical specimens taken from patients being treated with the topo I inhibitor topotecan. Because available antibodies were not sufficiently sensitive at the start of this project, we identified a highly specific human SCL-70 antibody from a patient with scleroderma, which allowed quantitative determination of topo I copy number in HeLa and HT-29 cell lines. Additional refinements of the Western blot technique were accomplished to improve signal:noise ratio. In surgical tumor specimens, we found the median topo I level to be 30.1 x 10(5) copies/cell for gastric adenocarcinomas, compared to 18.4 x 10(5) copies/cell for normal gastric mucosae in the same samples. For lung adenocarcinoma, the median protein level was 21.5 x 10(5) copies/cell, compared with the normal tissue counterpart protein level of 12.7 x 10(5) copies/cell. The median tumor:normal ratios from paired samples of these tumor types were 1.51 and 1.84, respectively. As part of a Phase II study evaluating the efficacy of topotecan (1.5-2.0 mg/m2 daily for 5 days) in upper gastrointestinal malignancies, we obtained tumor and normal mucosa biopsies in 11 patients with gastric or esophageal cancer, 30 min after administration on day 4 or 5. Three patients with gastric adenocarcinoma had stable disease as their best response, with the remainder of patients progressing. Improvement in Western blotting methodology allowed the quantitation of topo I levels in these gastric and esophageal cancer biopsies, which could be augmented by brief heating to release complexed topo I. We were also able to directly visualize high molecular weight topo I-containing bands, which were shown to be cleavable complexes by heat reversal, with restoration of the topo I Mr 100,000 band. Using this heat reversal technique, we determined the presence of cleavable complex in a total of 7 of 11 patient biopsy samples (5 tumors and 2 normal mucosae). In patients treated with topotecan on this dose and schedule, we determined that a median of 73% of the total tumor topo I was involved in cleavable complex (range, 18.3-91%). The intensity of the Mr 100,000 topo I band in biopsy specimens of patients receiving topotecan represented "free" or noncomplexed topo I. The median copy number for the residual, noncomplexed topo I (n = 11) was 7.36 x 10(5) copies/cell, significantly less than the median of 30.1 x 10(5) copies/cell for random tumor specimens from patients with gastric adenocarcinomas (P < 0.001). Pharmacodynamic analysis demonstrated a negative correlation between the noncomplexed topo I copy number and topotecan area under the curve (Spearman rank test: r(s) = -0.81, P = 0.003). Nonlinear regression analyses of these data were best fit with an inhibitory maximum effect model, yielding parameter estimates for Emax and EC50 of 29.3 x 10(5) copies/cell (coefficient of variation = 22%) and 43.1 ng x h/ml (coefficient of variation = 27%), respectively. Through a series of careful modifications and refinements, we have improved the Western blot assay for topo I for use in clinical monitoring. We have demonstrated the ability to directly visualize cleavable complex in patients being treated with topo I inhibitor therapy and have directly quantitated free topo I, as well as the key topo I intermediate (cleavable complex), in biopsy specimens obtained from pat

Minimal RNA constructs that specifically bind aminoglycoside antibiotics with high affinities

RNA molecules are the functional targets for aminoglycosides. In order to approach an understanding of the rules which underlie aminoglycoside-RNA recognition, high-affinity RNA aptamers have been prepared which discriminate among various aminoglycosides [Wang et al. (1996) Biochemistry 35, 12338-12346]. One of these aptamers, J6, which is 109 nts in length, binds the aminoglycoside tobramycin stoichiometrically with a dissociation constant of 0.77 +/- 0.03 nM. Aminoglycosides, similar in structure to tobramycin, bind with affinities diminished by 10(3)-10(4) compared to tobramycin. Experiments are reported here which are designed to reveal the nature of the tobramycin binding domain of J6. A small (40 nts) stem-loop derivative of J6, containing a 3 nt and a 1 nt bulge, stoichiometrically binds tobramycin with a dissociation constant of approximately 5 nM. This construct can strongly discriminate between similar aminoglycosides with respect to binding. Elimination of either the three or the single nucleotide bulge eliminates specific aminoglycoside binding. The structure of the loop region is also critical. These studies demonstrate that simplified RNA molecules can be generated which bind aminoglycosides specifically and with high affinities.

Phase I/II trial of low dose cyclosporin A with EP for advanced non-small cell lung cancer

We and others have shown that cyclosporin A (CsA) reverses resistance to etoposide (E) and cis-platinum (P) in vitro and in vivo. To assess the clinical relevance of combined therapy, we studied CsA with EP in patients with advanced non-small cell lung cancer in a phase I/II clinical trial in a University setting. Patients were treated between July 1989 and June 1994 and included 10 females and 34 males with a median age of 61 years and a mean Karnofsky performance status of 80. CsA was given at escalating doses of 1-6 mg/kg per day on days 1-4 of each 21 day cycle with cis-platinum 25 mg/m2 per day and etoposide 100 mg/m2 per days on days 1-3. Response was assessed after each 2 cycles by measuring index lesions. A total of 44 patients received 133 cycles, 22.7% of patients had a partial response and 36.4% had stable disease with 8% 2-year survival. Patients receiving 1-2 mg/kg CsA had a PR rate of 37.5 and 50% SD compared to 19.4 and 33.3% for doses of 3 mg/kg or more. Although no conclusions should be drawn from this small study, the Kaplan-Meier survival curves were statistically significant different for these two groups by the log-rank test (P = 0.047). The 2-year survival of the former group was 25% compared to 4% for the latter. In light of the potential importance of immunomodulation in cancer control, it seems prudent to balance the effects of CsA on P-glycoprotein and other drug resistance pumps against its dose-dependent immunosuppressive activity. Further studies are needed to validate the activity of low dose CsA in combination with standard chemotherapy for lung cancer.

Chemotherapeutic activity of synthetic antimicrobial peptides: correlation between chemotherapeutic activity and neutrophil-activating activity

The chemotherapeutic activity of three synthetic antibacterial peptides was investigated. KLKLLLLLKLK-NH2 and its D-enantiomer showed significant chemotherapeutic activity in MRSA-infected mice, whereas KLKLLLKLK-NH2, which showed the highest antibacterial activity among them in vitro, was found to have almost no ability to prevent MRSA infection. These results suggest that the antibacterial activity of peptides assessed in vitro does not necessarily correlate with their chemotherapeutic activity. We found that KLKLLLLLKLK-NH2 and its D-enantiomer, but not KLKLLLKLK-NH2, have the ability to activate human neutrophils to produce superoxide, suggesting that the prevention of MRSA infection by these peptides is not simply due to their direct bactericidal activity but to augmentation of the systemic defense mechanism mediated by neutrophils.

Differential effects of aging on NADPH-diaphorase and VIP neurons in cerebral cortex of rats

Age-related changes of NADPH-diaphorase (NADPH-d) and vasoactive intestinal polypeptide (VIP) were examined in the rat brain. Aged (24 months) rats showed a significant decrease in the number of VIP-immunoreactive (IR) neurons in the cerebral cortex when compared with control (4 months) rats. However, the number of NADPH-d-positive neurons was not significantly different in the two groups. Quantitative analysis of cell areas revealed a significant shrinkage of VIP-IR neurons in the aged group, whereas no further cell shrinkage was noted for NADPH-d-positive neurons compared with the control group. These morphometric results demonstrate that NADPH-d-containing neurons are more resistant to aging than the VIP-IR neurons in the cerebral cortex of rats.

Distributions of single neurons related to body parts in the lateral striatum of the rat

Single unit recordings in awake, unrestrained rats confirmed and extended previous findings regarding the functional organization of the lateral striatum. In individual electrode tracks, clusters of neurons related functionally to an individual body part were interspersed with clusters related to other body parts. The overlapping distributions of these neurons were arranged somatotopically in the dorsal-ventral dimension. The distribution of hind limb neurons was most dorsal and showed no overlap with the distribution of neurons related to oral sensorimotor activity. Oral representation was most ventral of all body parts and extended to the ventral boundary of the lateral striatum. Representations of other body parts overlapped with that of the hind limb dorsally but differed primarily in the degree to which they extended ventrally. Forelimb representation extended farther ventrally than that of the hind limb, but did not extend as far ventrally as that of the neck. Despite substantial overlap in the dorsal-to-ventral order of hind limb-forelimb-neck-face representations, single neurons showed no evidence of overlap, or convergence, of body parts. These data provide a more complete description of the dorsal-ventral somatotopy in the lateral striatum of the rat, which as shown previously, extends throughout the medial-lateral, and much of the anterior-posterior dimensions of the lateral striatum.

Toll, a muscle cell surface molecule, locally inhibits synaptic initiation of the RP3 motoneuron growth cone in Drosophila

Toll, a transmembrane molecule with extracellular leucine-rich repeats, is dynamically expressed by the Drosophila embryonic musculature. Growth cones of RP3 and other motoneurons normally grow past Toll-positive muscle cells and innervate more distal muscle cells, which have down-regulated their Toll expression. In this study, we show that reciprocal genetic manipulations of Toll proteins can produce reciprocal RP3 phenotypes. In Toll null mutants, the RP3 growth cone sometimes innervates incorrect muscle cells, including those that are normally Toll-positive. In contrast, heterochronic misexpression of Toll in the musculature leads to the same growth cone reaching its correct target region but delaying synaptic initiation. We propose that Toll acts locally to inhibit synaptogenesis of specific motoneuron growth cones and that both temporal and spatial control of Toll expression is crucial for its role in development.

Quantitative study of the short range order in B2O3 and B2S3 by MAS and two-dimensional triple-quantum MAS 11B NMR

Two-dimensional multiple-quantum magic angle spinning (MQMAS) NMR and MAS NMR of 11B at various magnetic fields, were applied to elucidate the structure of vitreous (glassy) boron trioxide (v-B2O3), vitreous boron trisulfide (v-B2S3) and crystalline boron trisulfide (c-B2S3). These techniques, when combined with computer simulations of the resulting spectra, provide the isotropic chemical shifts and the quadrupole parameters, as well as a quantitative measure of the intensities of various boron resonances. The MAS NMR of v-B2O3 produced overlapping anisotropic lineshapes corresponding to the -1/2<-->1/2 transition in two distinct types of BO3 units with 3(+/-0.08):] intensity ratio. A combination of MAS and the multiple-quantum method resulted in a better resolved, isotropic 11B spectrum of v-B2O3. A remarkable enhancement of resolution of the MQMAS NMR proved instrumental in finding and identifying various impurities present in v-B2S3 and c-B2S3. In addition to the resonances from boron in two types of BS3 groups, four other structural units, BOS2, BO2S, BO3 and BS4, were elucidated from the spectra of vitreous and crystalline samples. The effects of various experimental parameters, such as the magnitude of the B0 and B1 fields, on the resolution of the MAS and MQMAS techniques are also shown.

Activation of Stat1 by mutant fibroblast growth-factor receptor in thanatophoric dysplasia type II dwarfism

The achondroplasia class of chondrodysplasias comprises the most common genetic forms of dwarfism in humans and includes achondroplasia, hypochondroplasia and thanatophoric dysplasia types I and II (TDI and TDII), which are caused by different mutations in a fibroblast growth-factor receptor FGFR3 (ref. 1). The molecular mechanism and the mediators of these FGFR3-related growth abnormalities are not known. Here we show that mutant TDII FGFR3 has a constitutive tyrosine kinase activity which can specifically activate the transcription factor Stat1 (for signal transducer and activator of transcription). Furthermore, expression of TDII FGFR3 induced nuclear translocation of Stat1, expression of the cell-cycle inhibitor p21(WAF1/CIP1), and growth arrest of the cell. Thus, TDII FGFR3 may use Stat1 as a mediator of growth retardation in bone development. Consistent with this, Stat1 activation and increased p21(WAF1/CIP1) expression was found in the cartilage cells from the TDII fetus, but not in those from the normal fetus. Thus, abnormal STAT activation and p21(WAF1/CIP1) expression by the TDII mutant receptor may be responsible for this FGFR3-related bone disease.

Posttrauma thromboembolism prophylaxis

PURPOSE

The need to study methods of thromboembolism prophylaxis in high-risk trauma patients is well established. The purpose of this study was to evaluate the feasibility of a proposed study design, including current methods of prophylaxis, performance of a risk assessment profile scale, and the use of serial color-flow duplex studies in detecting deep venous thrombosis (DVT).

METHODS

Patients were enrolled into the study, stratified as to their ability to receive anticoagulation and randomized to low-dose unfractionated heparin, low molecular weight heparin, pneumatic compression devices, or foot pumps with or without vena caval filters. Serial ultrasound scans were performed at designated intervals for 4 weeks. Pulmonary angiograms were obtained for clinical signs or symptoms of pulmonary embolism.

RESULTS

Fifty-three patients, 32 male and 21 female patients with a mean age of 44 years, completed the study. The incidence of DVT was 43% (23 of 53 patients) and significantly higher in older patients. There were no pulmonary embolisms. Color-flow duplex proved to be a sensitive method for detecting both proximal and distal thrombi. The risk assessment profile for thromboembolism (RAPT) scale identified a group of patients with a high incidence of DVT. However, the occurrence of DVT was not correlated with the magnitude of the RAPT score.

CONCLUSION

The ability to identify a population with a high incidence of thromboembolism by using the RAPT score to detect asymptomatic DVT, and the suggested advantage of low molecular weight heparin, all support the need for an appropriately powered randomized clinical trial.

Tachycitin, a small granular component in horseshoe crab hemocytes, is an antimicrobial protein with chitin-binding activity

Small granules of horseshoe crab hemocytes contain two known major antimicrobial substances, tachyplesin and big defensin (S5), and at least five protein components (S1 to S6), with unknown functions. In the present study, we examined the biological properties and primary structure of a small granular component S2, named tachycitin. This component was purified from the acid extract of hemocyte debris by two steps of chromatography. The purified tachycitin was a single chain protein with an apparent M(r) = 8,500 on Tricine-SDS-polyacrylamide gel electrophoresis. Ultracentrifugation analysis revealed tachycitin to be present in monomer form in solution. Tachycitin inhibited the growth of both Gram-negative and -positive bacteria, and fungi, with a bacterial agglutinating property. Moreover, tachycitin and big defensin acted synergistically in antimicrobial activities. The amino acid sequence and intrachain disulfide bonds of tachycitin were determined by amino acid and sequence analyses of peptides produced by enzymatic cleavages. The mature tachycitin consisted of 73 amino acid residues containing five disulfide bonds with no N-linked sugar. A cDNA coding for tachycitin was isolated from a hemocyte cDNA library. The open reading frame coded for an NH2-terminal signal sequence followed by the mature peptide and an extension sequence of -Gly-Arg-Lys at the COOH-terminus, which is a putative amidating signal. The COOH-terminal threonine amide released after digestion of tachycitin with lysylendopeptidase was identified. The NH2-terminal 28 residues of tachycitin shows sequence homology to a part of chitin-binding regions found in antifungal chitin-binding peptides, chitin-binding lectins, and chitinases, all of which have been isolated from plants. Tachycitin showed a specific binding to chitin but did not bind with the polysaccharides cellulose, mannan, xylan, and laminarin. Tachycitin may represent a new class of chitin-binding protein family in animals.

Cyclic polyamides for recognition in the minor groove of DNA

Small molecules that specifically bind with high affinity to any designated DNA sequence in the human genome would be useful tools in molecular biology and potentially in human medicine. Simple rules have been developed to rationally alter the sequence specificity of minor groove-binding polyamides containing N-methylimidazole and N-methylpyrrole amino acids. Crescent-shaped polyamides bind as antiparallel dimers with each polyamide making specific contacts with each strand on the floor of the minor groove. Cyclic polyamides have now been synthesized that bind designated DNA sequences at subnanomolar concentrations.

Availability of discographic computed tomography in automated percutaneous lumbar discectomy

Automated percutaneous lumbar discectomy (APLD) has been developed since 1984 when Gary Onik first attempted it. This procedure has many advantages and has been used widely in the treatment of protruded disc diseases. The success rate of APLD by authors from March 1988 to February 1993 when the discographic computed tomography (CT) had not been performed was 74%. In evaluating lumbar disc diseases, we have used discographic CT. According to the patterns of dye distribution in the disc, two different types of protrusion can be distinguished: broad dye base protrusion and narrow dye base protrusion. From April 1993 to July 1994, 52 patients with protruded disc diseases were performed discographic CT. 23 Patients had narrow dye base protrusion and 29 patients had broad dye base protrusion. 29 patients with a broad dye base on discographic CT were treated with APLD and evaluated. The success rate in these patients was 93% by Macnab's criteria. Thus, we suggest that it is mandatory to apply discographic CT to increase the success rate of APLD in patients with protruded disc diseases.

A novel big defensin identified in horseshoe crab hemocytes: isolation, amino acid sequence, and antibacterial activity

Hemocytes of the horseshoe crab (limulus) contain a family of arthropodous peptide antibiotics, termed the tachyplesin family, and antibacterial protein, called anti-LPS factor, of which the former is located in the small (S) granules and the latter in the large (L) granules of the hemocytes. In our ongoing studies on granular components, we have identified here a novel defensin-like substance present in both L- and S-granules. This substance strongly inhibits the growth of Gram-negative and -positive bacteria, and fungi, such as Candida albicans. The isolated substance, tentatively termed "big defensin," consists of 79 amino acid residues, of which the COOH-terminal 37 residues have a sequence similar to those of mammalian neutrophil-derived defensins, especially rat defensin. Characterization of the disulfide motif in big defensin indicated that the disulfide array is identical to that of beta-defensins from bovine neutrophils. One clear structural difference is that the limulus hemocyte-derived big defensin has an extension of the NH2-terminal hydrophobic sequence with 35 amino acid residues followed by the COOH-terminal cationic defensin portion. This amphipathic nature of big defensin seems likely to be associated with its potent antibacterial activity. Furthermore, antibacterial activities of the NH2-terminal hydrophobic region and the COOH-terminal defensin portion separated by tryptic digestion are significantly different: the former displays a more potent activity against Gram-positive bacteria, whereas the latter is more potent against Gram-negative bacteria. Big defensin, therefore, may prove to represent a new class of defensin family possessing two functional domains with different antimicrobial activities.

Complications following Gamma Knife radiosurgery

Between May 1992 and February 1994, 213 lesions in 183 consecutive patients were treated with Gamma Knife radiosurgery at Severance Hospital, Yonsei University, Seoul, Korea. During this period, we experienced 2 deaths, 1 directly and another indirectly related to irradiation. Nonfatal complications included 1 tumor bleeding, and 4 ventriculoperitoneal shunts had to be inserted due to aggravation of preexisting hydrocephalus. Radiation-induced imaging changes developed in 23.6% of the cases followed up for more than 6 months. Among 24 lesions of 8 cavernous hemangiomas, all 4 cases with lesions larger than 1.5 cm3 developed imaging changes.

Collateral sensitivity to radiation and cis-platinum in a multidrug-resistant human leukemia cell line

Although collateral sensitivity to gamma radiation has previously been described in multidrug-resistant tumor cell lines, we describe here a multidrug-resistant human T-cell acute lymphatic leukemia cell line, L100, which displayed increased sensitivity to both gamma radiation and cis-platinum. Cis-platinum cytotoxicity of parental L0 cells and L100 cells was enhanced, whereas radiation sensitivity of L0 and L100 cells was unaltered by glutathione depletion. These results indicate that disparate mechanisms are operative in the collateral sensitivity of L100 cells to gamma radiation and cis-platinum.

Loss of developing cholinergic basal forebrain neurons following excitotoxic lesions of the hippocampus: rescue by neurotrophins

Previous studies have demonstrated that the viability of developing cholinergic basal forebrain neurons is dependent upon the integrity of neurotrophin-secreting target cells. In the present study, we examined whether infusions of nerve growth factor (NGF) or brain-derived neurotrophic factor (BDNF) could prevent the loss of cholinergic septal/diagonal band neurons following excitotoxic lesions of their target neurons within the hippocampus. Postnatal Day 10 rat pups received unilateral intrahippocampal injections of ibotenic acid. Rats then received intracerebroventricular (icv) injections of nerve growth factor (30 micrograms/injection), brain-derived neurotrophic factor (60 micrograms/injection), or saline immediately following the lesion and continuing every third day for 27 days. Both saline- and BNDF-treated rats displayed a significant loss of septal/diagonal band neurons expressing the protein and mRNA for choline acetyltransferase (ChAT) and p75 low-affinity nerve growth factor receptor ipsilateral to the lesion. The magnitude of this loss was significantly attenuated in BNDF-treated rats. Many remaining neurons were atrophic with stunted dendritic processes. In contrast, NGF treatment completely rescued these cells and prevented the shrinkage of remaining cholinergic septal neurons. In addition, both NGF and BDNF induced a sprouting of cholinergic processes within the residual hippocampal remnant ipsilateral to the infusions. The present study demonstrates that icv injections of NGF, and to a lesser extent BDNF, prevent the loss of developing basal forebrain neurons which occurs following removal of normal target cells. Diffusion studies revealed relatively poor penetration of BDNF into brain parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell cycle progression in the developing Drosophila eye: roughex encodes a novel protein required for the establishment of G1

The onset of pattern formation in the developing Drosophila eye is marked by the simultaneous synchronization of all cells in the G1 phase of the cell cycle. These cells will then either commit to another round of cell division or differentiate into neurons. Although cell cycle synchronization occurs in roughex (rux) mutants, cells circumvent G1 and all cells enter S phase, including cells that would normally differentiate. This leads to defects in early steps of pattern formation and cell fate determination. rux is suppressed by mutations in genes that promote cell cycle progression (i.e., cyclin A and string) and enhanced by mutations in genes that promote differentiation (i.e., Ras1 and Star). rux encodes a novel protein of 335 amino acids. We propose that rux functions as a negative regulator of G1 progression in the developing eye.

Endodermal sinus tumor: immunophenotypic expression of a carcinoma

A series of five endodermal sinus tumors was studied for their cytoskeletal and other phenotypic markers. They included 2 ovarian, 2 testicular, and 1 inguinal tumors. The cytoskeletal expression was also studied by gel electrophoresis and immunoblotting. Every tumor was diffusely and strongly immunostained for cytokeratin. By SDS-PAGE and immunoblotting, cytokeratins 8 & 18 were detected. Vimentin was focally coexpressed in 4 cases. The stroma was diffusely immunostained for vimentin. None of them expressed desmin, neurofilament, or glial filament protein. Desmoplakin was expressed only in one ovarian tumor. Alpha-fetoprotein and S-100 protein were also diffusely positive among the neoplastic cells; intracytoplasmic globules were especially strongly immunostained. These findings suggest that endodermal sinus tumors represent a group of pure malignant epithelial neoplasms, and may be regarded as primitive carcinomas.