gamma-Glutamyl transpeptidase in normal and neoplastic prostate glands

gamma-Glutamyl transpeptidase (GGT) is a cytoplasmic membrane-bound enzyme important in the metabolism of glutathione and other gamma-glutamyl compounds. It is present in highest levels in the kidney and is also expressed prominently in reproductive organs such as the prostate gland. Because GGT has never been examined in prostatic carcinoma, we used a new polyclonal antibody (GGT 129) for immunohistochemical localization of GGT in normal prostate gland and 72 prostatic carcinomas. The normal lining secretory cells of ducts and acini showed apical immunoreactivity for GGT, but the basal epithelial cells were negative. Most of the prostatic adenocarcinomas had GGT staining patterns and intensity similar to those of normal prostatic secretory cells, because the majority of neoplastic cells showed immunopositivity in more than 80% of the adenocarcinomas. In comparing the percentage of cells staining for GGT with clinicopathologic parameters, there was no correlation between the number of positive cells and the Gleason score, the percentage of intraglandular carcinoma, capsule penetration, or seminal vesicle invasion. Immunostaining for GGT lacks value as a prognostic factor and does not correlate with standard clinicopathologic parameters. GGT may be important, however, for growth and maintenance of both normal and neoplastic prostatic cells. Modulating GGT levels or administering drugs that can be activated by GGT may have therapeutic value.

Effect of lactation on insulin signal transduction in sheep adipose tissue and skeletal muscle

The molecular basis of the insulin resistance of adipocytes and skeletal muscle during lactation has been investigated in sheep. The number of insulin receptors per adipocyte or per unit membrane protein for skeletal muscle is unchanged by lactation. The ability of insulin to stimulate autophosphorylation of its beta-subunit was enhanced in adipocytes but not in skeletal muscle during lactation. This increased autophosphorylation was due, at least in part, to enhanced tyrosine phosphorylation and was found when both solubilised, immunoprecipitated insulin receptors and intact adipocytes were incubated with insulin. The ability of the insulin receptor kinase to phosphorylate other proteins did not appear to be altered by lactation; this was shown with lectin-purified insulin receptors using the artificial substrate, polyglutamyl tyrosine, and in intact adipocytes. Lactation had no effect on the ability of insulin to activate two key downstream kinases, mitogen-activated protein kinase and phosphatidyl inositol-3-kinase in adipocytes. The study thus shows that the insulin resistance of lactation in sheep is due to changes downstream of the receptor in both adipocytes and skeletal muscle.

Ovarian granulosa cell tumors with bizarre nuclei: an immunohistochemical analysis with fluorescence in situ hybridization documenting trisomy 12 in the bizarre component [corrected]

Granulosa cell tumors with bizarre nuclei (GCT-BN) are rare lesions with a prognosis apparently similar to that of conventional granulosa cell tumors (GCT-NOS). The immunohistochemical features of GCT-BN have not been described, and the exact nature of the bizarre nuclei (BN) is unclear. Thirteen GCT-BN were studied with antibodies to cytokeratin, vimentin, epithelial membrane antigen, muscle-specific actin, alpha smooth muscle actin, desmin, and S-100 protein. Six cases were also examined by fluorescence in situ hybridization for trisomy 12, a nonrandom chromosomal aberration found in a proportion of ovarian sex-cord stromal tumors. Histologically, 12 tumors (86%) contained BN areas interspersed with large areas of GCT-NOS. The remaining tumor contained only microscopic foci of GCT-NOS. Immunohistochemically, the tumors stained for vimentin (13 tumors), S-100 protein (11 tumors), muscle-specific actin (10 tumors), cytokeratin (eight tumors), alpha smooth muscle actin (eight tumors), and desmin (one tumor), but none stained for epithelial membrane antigen. Immunostaining results for the BN and GCT-NOS areas were concordant in eight (73%) of the 11 tumors in which both areas could be independently assessed. The remaining three tumors (27%) showed discordant results for only one of the eight markers used. In five patients, trisomy 12 was detected by fluorescence in situ hybridization in areas of BN but not in areas of GCT-NOS present in the same tumor. Trisomy 12 was also present in another BN tumor in which the foci of GCT-NOS were too small to be evaluated. We conclude that within GCT-BN, areas with BN are immunohistochemically similar to areas of GCT-NOS present in the same tumor. The finding of trisomy 12 in areas with BN but not GCT-NOS in the same tumor, however, suggests that cells with BN represent a genetically distinct clone of tumor cells arising within GCT-NOS.

Angiosarcoma-like neoplasms of epithelial organs: true endothelial tumors or variants of carcinoma?

Past experience has shown the existence of tumors in various viscera that assume growth patterns that are usually associated with angiosarcomas of skin and soft tissue. The lineage of differentiation pursued by the former of these proliferations has been the subject of controversy, with some investigators concluding that "angiosarcomatoid" neoplasms of solid organs were, in actuality, variants of high-grade carcinomas. The latter statement does appear to have partial validity, inasmuch as immunohistologic, ultrastructural, and clinical data on "pseudovascular carcinomas" do support their basic identity with high-grade epithelial malignancies of the breasts, skin, and lungs. Those lesions show uniform reactivity for keratin and epithelial membrane antigen, but they fail to express von Willebrand factor, CD31, or CD34, which are regarded as endothelial determinants. On the other hand, however, angiomatoid neoplasms of the thyroid gland are more complex; some represent indisputable carcinomas, others manifest seemingly "pure" mesenchymal phenotypes, and still others display a mixture of epithelial and endothelial phenotypes at ultrastructural and protein-chemical levels of specialized investigation. At present, it must be acknowledged that the distinction between angiomatoid thyroid carcinomas and "true" thyroid angiosarcomas is an academic one, because the prognoses and treatments for these lesions are essentially identical.

Sinonasal intestinal-type adenocarcinoma: immunohistochemical profile and comparison with colonic adenocarcinoma

Sinonasal intestinal-type adenocarcinomas (ITAC), as their name implies, bear a striking resemblance to primary intestinal neoplasia. The value and limitations of immunohistochemistry in making this distinction have not been previously defined. We determined the immunohistochemical staining profile of 12 sinonasal ITAC and compared their staining with that of 12 histologically similar colonic adenocarcinomas. All ITAC stained for cytokeratin and epithelial membrane antigen. Additional positive reactions were as follows: B72.3, 11 of 12; Ber EP4, 11 of 12; Leu M1, 8 of 12; HMFG-2, 12 of 12; and BRST-1, weak staining in seven of 12 cases. All 12 ITAC were negative for vimentin, synaptophysin, and actin. Colonic carcinomas stained similarly for these markers. Three additional antigens differed in their expression in ITAC versus colonic tumors. Carcinoembryonic antigen was strongly present in only two of 12 ITAC, with focal positivity in six of 12 and no staining in four of 12 cases. In contrast, all 12 colonic adenocarcinomas were strongly positive for carcinoembryonic antigen. Chromogranin-positive cells were present and often numerous in nine of 12 ITAC, in contrast to only rare positive cells in three of 12 colonic tumors. Neuron-specific enolase was present in five of 12 ITAC but was absent from all colonic tumors studied. ITAC are less often and less strongly carcinoembryonic-antigen positive and more prone to exhibit divergent neuroendocrine differentiation. These features may be of some value in distinguishing ITAC and colonic metastases. Neuroendocrine differentiation in ITAC was associated with higher mortality. Of the five patients with ITAC having 1+ to 2+ chromogranin positivity, only one was free of disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Tuberculosis infection in U.S. Air Force dentists

PURPOSE

To determine if U.S. Air Force dentists have a significantly higher prevalence of infection from M. tuberculosis than a similar no-dentist group.

MATERIALS AND METHODS

A written survey instrument was sent to all active duty Air Force dentists and lawyers. The survey asked individuals to voluntarily and anonymously give information regarding positive tuberculin skin testing which was subsequently treated with antituberculosis medication. Only positive responses which occurred during the time the respondent was practicing as a dentist or lawyer in the Air Force were counted. Significant exposures were considered to have occurred in those persons who were evaluated by a physician and actually put on a course of antituberculosis medication.

RESULTS

The dentists returned 82.7% of the 1256 surveys sent, of which 2.37% indicated a significant exposure. The lawyers returned 79.6% of 1321 surveys, of which 1.47% were positive for significant exposure. Chi-square analysis indicated no significant difference between the two groups (P = 0.14).

Colorectal carcinoma in patients 30 years of age and younger

Thirty-seven cases of colorectal cancer in patients aged 30 years or younger have been treated at the University of Virginia Health Sciences Center from 1957 through 1992. The present series, comprising patients treated from 1978 through 1992, updates a series presented from our institution comprising patients treated from 1957 through 1977. For the 36-year series, 24 patients (65%) were female, and 13 (35%) were male. Sixteen patients (43%) were black, and 21 patients (57%) were white. Sites of tumor and their frequency were rectosigmoid, 14 (38%), left colon, five (14%), splenic flexure, two (5%), transverse colon, three (9%), hepatic flexure, two (5%), right colon, two (5%), and cecum, six (16%). Twenty-two patients (59%) presented with abdominal pain, whereas 15 (41%) presented with hematochezia or hemoccult positive stools. The average time of onset of symptoms to diagnosis was 2.3 months. Thirty-four of 37 patients (92%) presented with advanced stage disease. Only four patients had precancerous conditions: one each with Gardner's Syndrome, Turcot's Syndrome, ulcerative colitis, and villous adenoma. Twenty-five patients (68%) underwent surgery for cure, and ten (27%) received palliative procedures. Nothing could be done for two patients (5%). Twenty-one patients (57%) had mucinous histology, 13 (35%) had typical adenocarcinoma, one (3%) had small cell carcinoma, and histology was unavailable in two (6%). Nodes were negative in only 10 (27%) patients, of which only three had mucinous histology. There have been five 5-year survivors and three patients alive and disease free at last follow up, ranging from 30 months to 48 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Medullary carcinoma of the breast: interobserver variability in histopathologic diagnosis

To assess the interobserver reproducibility for the diagnosis of medullary carcinoma of the breast (MC), 53 previously diagnosed MCs were independently assessed by six observers for growth pattern, nuclear grade (NG), inflammation, tumor margin, intraductal component, and glandular features. Tumors were reclassified as MC, atypical MC, or infiltrating ductal carcinoma according to the histopathologic criteria of Ridolfi et al. (Cancer 40:1365, 1977), Wargotz and Silverberg (Hum Pathol 19:1340, 1988), and Pedersen et al. (Br J Cancer 63:591, 1991). NG was the most reproducible parameter, and tumor margin was the least, with consensus agreement by four of six observers for 49 (92%) and 26 (49%) of cases, respectively. Utilizing the histopathologic criteria proposed by Ridolfi et al., Wargotz and Silverberg, and Pedersen et al., consensus diagnoses were achieved in 37 cases (70%), 46 cases (87%), and 51 cases (96%), respectively. A consensus diagnosis of MC in all three systems was unassociated with tumor size, axillary lymph node status or overall survival (median follow-up: 89 mo). The consensus (or better) reclassification of 44/53 (83%), 35/53 (66%), and 27/53 (51%) previously diagnosed MC as atypical MC or infiltrating ductal carcinoma by the criteria of Ridolfi et al., Wargotz and Silverberg, and Pedersen et al., respectively, suggests that MC was previously over-diagnosed. While the scheme of Pedersen et al. is the most reproducible, additional follow-up information is necessary to determine the biological significance of this classification system. To minimize these difficulties in practice, pathologists should carefully adhere to published criteria and indicate the classification system utilized.

Aggressive papillary tumor of middle ear/temporal bone and adnexal papillary cystadenoma. Manifestations of von Hippel-Lindau disease

The occurrence of an aggressive papillary middle ear/temporal bone tumor (APMET) and a benign adnexal papillary tumor of probable mesonephric origin (APMO) in a patient with von Hippel-Lindau disease (VHL) is reported. Histologically, both tumors were identical to papillary cystadenomas of the epididymis and broad ligament of probable mesonephric derivation. A comprehensive literature review showed that including the current case, seven of 46 (15%) documented cases of APMET and four of four (100%) cases of APMO arose in patients with VHL. Given an estimated minimum birth incidence of 1/36,000, a one-sample test of binomial proportion using the exact method establishes that the association of APMET and APMO with VHL is highly significant (p = 1.4 x 10(-24) and 1 x 10(-18), respectively). The data indicate that APMET and APMO may represent major visceral manifestations of VHL. Accordingly, in the presence of one of these tumors strong consideration should be given to the diagnosis of VHL, given either the presence of another major component of VHL or documentation of VHL in at least one consanguineous relative.

Angiomatoid carcinoma and 'angiosarcoma' of the thyroid gland. A spectrum of endothelial differentiation

The existence of angiosarcoma of the thyroid gland and its relation to angiomatoid carcinoma have been debated. The authors reviewed eight angiomatoid thyroid neoplasms. Controls consisted of six sarcomatoid thyroid carcinomas without angiomatoid features and an angiosarcoma metastatic to the thyroid gland. All eight angiomatoid neoplasms consisted of epithelioid cells with prominent eosinophilic cytoplasm lining vascularlike spaces. All eight expressed vimentin. Four tumors were predominantly angiosarcomalike neoplasms, based on staining for factor VIII-related antigen (three of four), CD31 (four of four), CD34 (one of four), and Ulex europaeus I lectin (four of four); they lacked epithelial markers other than cytokeratin (two of four). Four tumors were designated as angiomatoid carcinomas, based on staining for multiple epithelial markers: cytokeratin (four of four), epithelial membrane antigen (three of four), thyroglobulin (three of four). Three angiomatoid carcinomas also expressed or labeled with one or more vascular markers: CD34 (one of four), CD31 (two of four), Ulex europaeus I lectin (one of four), factor VIII-related antigen (one of four). The metastatic angiosarcoma to the thyroid gland labeled for factor VIII-related antigen, vimentin, CD31, and with Ulex europaeus I lectin. It did not express CD34. The six sarcomatoid carcinomas without angiomatoid features stained for cytokeratin (four of six), epithelial membrane antigen (one of six), and vimentin (six of six). None labeled for thyroglobulin, factor VIII-related antigen, CD31, CD34, or with Ulex europaeus I lectin. Angiomatoid carcinomas of the thyroid gland exhibit both epithelial and endothelial features. "Angiosarcoma" may represent the extreme in this spectrum of endothelial differentiation. All tumors behaved in a similar clinical fashion characterized by persistent local disease, widespread metastases and poor prognosis.

Immunohistochemical detection of neuroblastomatous foci in composite adrenal pheochromocytoma-neuroblastoma

To determine if immunohistochemistry might aid in the identification of neuroblastomatous foci in composite adrenal tumors, the authors analyzed two examples of composite adrenal pheochromocytoma-neuroblastoma, 18 pure pheochromocytomas, and six pure neuroblastomas using peanut agglutinin and a panel of antibodies directed against neuroendocrine and neural-associated antigens. Pure pheochromocytoma had the following immunopositivity: vimentin 14/18, chromogranin 18/18, synaptophysin 18/18, S100 protein 0/18 (tumor cells), neurofilament 14/18, J1 beta-tubulin (J1) 18/18, microtubule-associated protein-2 13/18, glial fibrillary acidic protein 13/18, and peanut agglutinin 17/18. Pure neuroblastoma reacted positively as follows: vimentin 0/6, chromogranin 5/6, synaptophysin 4/6, S100 protein 0/6 (tumor cells), neurofilament 5/6, J1 6/6, microtubule-associated protein-2 6/6, glial fibrillary acidic protein 1/6, and peanut agglutinin 6/6. Each component of both composite tumors reacted similarly to the pure neoplasms. Although the frequency of positive staining was similar for pheochromocytoma and neuroblastoma, the intensity and pattern differed for several antigens. Pheochromocytoma was diffusely positive for synaptophysin and chromogranin, whereas staining was focal and punctate in neuroblastoma. Microtubule-associated protein-2, J1, and neurofilament antibodies highlighted the fibrillar background of neuroblastoma, which pheochromocytoma lacked. Pheochromocytoma contained focal, ball-like immunoreactivity for glial fibrillary acidic protein and vimentin, which was absent in neuroblastoma. These immunohistochemical distinctions can assist the clinically important recognition of neuroblastomatous foci in composite adrenal pheochromocytoma-neuroblastoma.

Expression of parathyroid hormone-related protein and its receptor in human umbilical cord: evidence for a paracrine system involving umbilical vessels

OBJECTIVE

Our purpose was to study the expression and localization of parathyroid hormone-related protein and expression of the parathyroid hormone/parathyroid hormone-related protein receptor in human umbilical cord.

STUDY DESIGN

The expression and localization of parathyroid hormone-related protein and expression of the parathyroid hormone/parathyroid hormone-related protein receptor were studied in isolated tissues from the human umbilical cord by Northern analysis, reverse-transcriptase polymerase chain reaction, Southern gel analysis, and immunolocalization procedures at the light and electron microscopic levels.

RESULTS

Parathyroid hormone-related protein was abundantly expressed in the umbilical cord. Immunohistochemical and immunocytochemical techniques confirmed hormone localization in the amnion epithelial layer and in vascular smooth muscle and endothelial cells in vessels from the umbilical cord and placental chorionic plate. Multiplex reverse-transcriptase polymerase chain reaction identified expression of receptor messenger ribonucleic acid in vessels of the umbilical cord; this finding was verified by means of Southern gel analysis of the products of the reverse-transcriptase polymerase chain reaction.

CONCLUSION

A parathyroid hormone-related protein paracrine system appears to exist in human umbilical cord. We suggest that it may be involved in the control of fetal placental circulation.

Detection of Epstein-Barr viral RNA in sinonasal undifferentiated carcinoma from Western and Asian patients

Undifferentiated carcinoma of the nasopharynx has a well-known association with Epstein-Barr virus (EBV), but only an inconsistent relationship has been identified in undifferentiated carcinomas occurring at other sites. We investigated 22 formalin-fixed, paraffin-embedded cases of sinonasal undifferentiated carcinomas (SNUCs) occurring in Western and Asian patients. A highly sensitive in situ hybridization method was performed using an antisense oligonucleotide probe to the EBER1 gene of EBV. We identified EBV RNA in seven of 11 SNUCs from Asian patients, but in none of the Western SNUC patients (0/11). The EBER1 signal was present in all or virtually all of the tumor cell nuclei in the seven EBV-RNA-positive Asian SNUCs. The latent membrane protein-1 (LMP1) of EBV was not identified in any of the five positive cases tested. Our results suggest that genetic predisposition or environmental/geographical cofactors play an important role in determining the strength of the association of SNUC with EBV.

Porcine somatotropin decreases acetyl-CoA carboxylase gene expression in porcine adipose tissue

Crossbred barrows were treated daily with porcine somatotropin (pST; 4 mg/d) from 79 to 127 kg BW to determine whether pST regulates the activity and gene expression of adipose tissue acetyl-CoA carboxylase (ACC), the rate limiting enzyme in de novo fatty acid synthesis. Administration of pST reduced ACC enzyme activity, protein content, and mRNA abundance in adipose tissue by 40 to 50%. When comparisons were made among all pigs, ACC enzyme activity and mRNA abundance were closely associated (r2 = .94). In summary, our results indicate that pST decreases ACC enzyme activity and that this is associated with a significant reduction in ACC mRNA abundance. We speculate that decreased ACC enzyme activity results from a reduction in ACC protein and that this occurs because pST reduces the abundance of mRNA available for translation.

The effect of ractopamine on beta-adrenoceptor density and affinity in porcine adipose and skeletal muscle tissue

We have evaluated the effect of feeding ractopamine (Rac), a phenethanolamine lean enhancer being developed for commercial use in finishing pigs, on beta-adrenoceptor (beta-AR) number and ligand-receptor binding affinity in adipose and muscle tissues. Pigs weighing 78 +/- 1 kg were fed Rac (20 mg/kg of diet) for 0 (control), 1, 8, or 24 d before being killed at 105 +/- 1 kg BW. beta-adrenoceptor density (per milligram of protein) was decreased by Rac up to approximately 50% in both the middle and the outer layers of subcutaneous (SQ) adipose tissue. Orthogonal contrasts indicated significant (P < or = .05) linear effects of Rac in middle and outer SQ adipose tissue, and also a significant (P < or = .05) quadratic effect of Rac in the middle layer. Ractopamine did not affect the maximal binding (Bmax) of longissimus muscle. The relative affinity with which the beta-AR population of the tissues examined bound the radioligand ([3H]dihydroalprenolol) was not influenced by Rac. Likewise, feeding Rac had no effect on the affinity of the beta-AR for Rac. The data indicate that a Rac-induced reduction in the Bmax of adipose tissue may account for the diminished in vitro lipolytic potency of exogenous Rac after prolonged periods of Rac feeding, and that Rac-induced desensitization differs between adipose and skeletal muscle tissues.

Limitations of ractopamine to affect adipose tissue metabolism in swine

To determine the temporal effect of ractopamine (Rac), a phenethanolamine, on adipose lipogenic enzyme activity and gene expression, 20 crossbred barrows were fed Rac (20 mg/kg of diet) for 0, 1, 8, or 24 d before slaughter (105 +/- 1 kg). Ractopamine had no effect (P > .05) on the activity of acetyl-coenzyme A carboxylase or malic enzyme in either the middle or outer layers of subcutaneous adipose tissue. Similarly, mRNA abundance for acetyl-coenzyme A carboxylase and the glucose transport proteins Glut 1 and Glut 4 were not affected by Rac in either adipose depot. Despite the inability of Rac to affect adipose tissue metabolism, Rac increased nitrogen retention, longissimus muscle area, and alpha-actin gene expression in skeletal muscle. Results indicate that Rac was not a functional beta-adrenergic agonist toward adipose tissue in this study. We suggest that the response to Rac in adipose tissue is masked by a combination of factors including tissue insensitivity, Rac-dose limitation, inherent partial agonism of Rac, and beta-adrenoceptor down-regulation.

Medullary carcinoma of the breast. Identification of lymphocyte subpopulations and their significance

Fifty-two infiltrating breast carcinomas with medullary features (BCMF) were studied immunohistochemically to determine the immunophenotype of the mononuclear tumor inflammatory cells (MTIC) in formalin-fixed, paraffin-embedded material. The neoplasms were also examined for Epstein-Barr virus (EBV) DNA by the polymerase chain reaction (PCR). BCMF were independently classified as medullary carcinoma (MC) or infiltrating ductal carcinoma (IDC) by six observers according to the criteria of Pedersen et al. DNA from 35 BCMF was successfully amplified using PCR, but all were negative for EBV DNA. These included, by 4/6 consensus diagnosis, 16 MC, 18 IDC, and one BCMF which failed to achieve consensus diagnosis. MTIC were present to a mild degree in 19 BCMF (37%) and to moderate to severe degrees in 33 (63%). MTIC were predominantly (> or = 75%) lymphocytic in 31 BCMF (13 MC, 16 IDC, two without consensus diagnostic agreement), and plasmacytic in 10 (six MC, four IDC); equal proportions of lymphocytes and plasma cells occurred in 11 (six MC, five IDC). Lymphocytic MTIC were mostly CD45RO+/CD3+ T-cells in nearly all cases, and showed a predominant CD3+/CD4+ and CD3+/CD4- immunophenotype in 36% and 64% of cases, respectively. Natural killer cells (CD57+) and histiocytes (MAC 387+) were virtually absent. The number, cell type, and T-cell subsets of the MTIC were unrelated to consensus diagnosis, axillary lymph node status, or overall survival. EBV is unassociated with MC, despite the histologic similarities of MC to EBV-associated lymphoepithelial lesions of other organs.(ABSTRACT TRUNCATED AT 250 WORDS)

The affinity of ractopamine, clenbuterol, and L-644,969 for the beta-adrenergic receptor population in porcine adipose tissue and skeletal muscle membrane

The affinities (Ki) with which ractopamine (RA), clenbuterol (CB), and L-644,969 (L6) bind the beta-adrenoceptor populations of adipose tissue (middle and outer subcutaneous [SQ] layers) and longissimus (LM) and semitendinosus (ST) muscle were determined. Within a given agonist, Ki values (nanomolar) were similar among tissues, except for RA, which had a higher (P < or = .05) affinity (lower Ki) for middle SQ adipose tissue than for outer SQ adipose and both muscles. For all tissues, binding affinities were greatest for CB (126), followed by L6 (350) and RA (856, exclusive of middle SQ adipose). The data indicate that both adipose and muscle tissues are targets of CB, RA, and L6 in vivo, and that tissue preferences of the agonists cannot be established from affinity data alone. The relatively constant affinity of the agonists for the various tissues examined implies that if tissue preferences exist, the efficiency with which postreceptor events are invoked by these agonists is the determining factor.

(-)-[3H]-dihydroalprenolol binding to beta-adrenergic receptors in porcine adipose tissue and skeletal muscle membrane preparations

We have characterized binding of (-)-[3H]dihydroalprenolol (DHA) to the beta-adrenergic receptor population in membrane from longissimus and semitendinosus muscles and subcutaneous adipose tissue (middle and outer layers) of pigs weighing 100 to 120 kg at slaughter. Linearity of specific binding with increasing membrane protein concentration was confirmed for muscle and adipose tissue. Specific binding was saturable; the beta-receptor population showed a high affinity for the radioligand. Half-maximal binding was achieved at similar concentrations of the tracer (.48 to .73 nM) in all tissues. Maximal binding (B max) per milligram of protein for skeletal muscle was approximately half of that for adipose tissue (P < or = .05) and was greater (P < or = .05) in membrane from the middle than in membrane from the outer layer of adipose tissue. Adipocyte membrane preparations yielded Kd estimates similar to those obtained with adipose tissue, but Bmax values were greater (P < or = .05). Kinetic rate constants were estimated and used to calculate the Kd for comparison to that derived from nonlinear regression analysis of Scatchard plots. Association (k1) and dissociation (k2) estimates were similar between tissues and the resulting Kd values were comparable to those derived from equilibrium data. Stereospecificity of binding was verified using the (-) and (+) isomers of the beta-adrenergic agonist isoproterenol; selectivity for the (-) form ranged from 8- to 19-fold. Overall, the most notable differences among tissues were in receptor density expressed per milligram of protein. Kinetic rate constants, Kd estimates, and the degree of selectivity for (-)-isoproterenol were similar.

Sarcomatoid carcinomas (carcinosarcomas) of the gastrointestinal tract: a review

This review discusses sarcomatoid carcinomas of the gastrointestinal tract, rare malignant neoplasms that demonstrate both epithelial and mesenchymal differentiation. The clinical, histological, immunohistochemical, and ultrastructural features are described. Practical problems in the differential diagnosis of these tumors are also discussed.

Radiotherapy for basaloid squamous cell carcinoma of the head and neck

Basaloid squamous cell carcinoma (BSCC) of the head and neck is a recently described high-grade variant of squamous cell carcinoma. It is a biologically virulent neoplasm with a propensity for nodal, as well as systemic, metastases. Because of the limited number of published reports, we reviewed data from patients of the University of Virginia Health Sciences Center and identified 16 cases of BSCC. The intent of this study was to determine the role of radiotherapy in the treatment of BSCC and better define the clinical features of this entity. Radiotherapy alone, or in combination with surgery, resulted in excellent local control rates. Distant metastases, chiefly pulmonary, occurred in more than half of the patients.