Serum carcinoembryonic antigen as a prognostic factor in resectable gastric cancer

BACKGROUND

Carcinoembryonic antigen (CEA) has been widely accepted as a tumor marker useful in the diagnosis and management of colorectal cancer. When CEA levels are positive in gastric cancer patients, they could be useful prognostic indicators. However, the value of CEA as a tumor marker for gastric cancer remains a matter of controversy.

STUDY DESIGN

We measured preoperative serum CEA levels in 196 patients with resectable gastric cancer between May 1986 and April 1996 and then evaluated the correlation between serum CEA levels, clinicopathologic features, and prognostic information.

RESULTS

Serum levels of CEA were above the normal range in 29 of 196 (14.8%) surgically resected patients (range, 5.2-570 ng/mL). Among 100 early gastric cancers confined to the submucosal layer, only 7 patients (7.0%) had positive CEA levels, but among 96 advanced cancers, 22 patients (22.9%) had high CEA levels. The CEA positive patients had more macroscopically infiltrative tumors, a more prominent serosal invasion, more frequent lymph nodes involvement, and a more advanced stage than did the CEA negative patients. The 3- and 5-year cumulative disease-specific survival rates of patients positive for serum CEA were 39.6% and 31.7%, respectively; these rates for patients negative for CEA were 83.0% and 77.3%, respectively (p < 0.0001 for comparison of survival curves). In various clinicopathologic parameters, nine parameters (tumor size, macroscopic type, type and time of operation, Laurén classification, depth of invasion, lymph node involvement, CEA, alpha-fetoprotein [AFP], and carbohydrate antigen [CA] 19-9) showed statistically significant differences in the cumulative survival rates. Of these nine parameters, independent prognostic factors by multivariate analysis were depth of invasion (T1, 2 versus T3, 4, p < 0.0001), serum CEA levels (negative versus positive, p = 0.0003), and lymph node metastasis (negative versus positive, p = 0.0005).

CONCLUSIONS

Preoperative serum CEA levels provide a predictive value in determining tumor stage and prognostic information for patients with potentially resectable gastric cancer during the preoperative period.

Excitatory synaptic transmission in the inner retina: paired recordings of bipolar cells and neurons of the ganglion cell layer

Properties of glutamatergic synaptic transmission were investigated by simultaneously voltage-clamping a pair of connected bipolar cells and cells in the ganglion cell layer (GLCs) in the newt retinal slice preparation. Activation of the Ca2+ current in a single bipolar cell was essential for evoking the glutamatergic postsynaptic current in the GLC. Depolarization for as short as 15 msec activated both NMDA and non-NMDA receptors. On the other hand, analysis of the spontaneous glutamatergic synaptic currents of GLCs revealed that these currents consisted of mainly non-NMDA receptor activation with little contribution from NMDA receptors. This suggests that non-NMDA receptors of GLCs are clustered in postsynaptic membrane regions immediately beneath the release sites of bipolar cells and that NMDA receptors have lower accessibility to the released transmitter than non-NMDA receptors. Glutamate that is spilled over from the release sites may activate the NMDA receptors. When a prolonged depolarizing pulse was applied to a bipolar cell, the response induced by non-NMDA receptors was limited greatly by their fast desensitization, whereas NMDA receptors were able to produce a maintained response. The relationship between the pulse duration applied to the bipolar cell and the integrated charge of the response evoked in the GLC was almost linear. Therefore, we propose that both non-NMDA and NMDA receptors cooperate to transfer the graded photoresponses of bipolar cells proportionally to GLCs.

G-CSF production in human bladder cancer and its ability to promote autocrine growth: a review

A variety of non-hematopoietic malignant tumors have been demonstrated to secrete granulocyte colony-stimulating factor (G-CSF) in amounts large enough to cause a significant systemic hematopoietic effect. Meanwhile, bladder cancer cells have been shown to secrete a variety of biological factors with no direct relation to urothelial cell origin. G-CSF produced by non-hematopoietic malignant cells in particular has been reported to be capable of inducing a leukemoid reaction in the host through intense stimulation of leukocyte production. This is most frequently associated with aggressive tumor cell growth and a poor clinical outcome. On the other hand, receptors for G-CSF have also been found on the cell surfaces of several non-hematopoietic cell types. These observations lead naturally to the tempting speculation that simultaneous acquisition of the ligand promotion and its receptor expression by a malignant tumor may provide a strong autocrine growth advantage. However, the role of autocrine growth factors in malignancy is even less clear, although it is undoubtedly important. In this review, G-CSF and tumor cell growth, particularly of human transitional cell carcinomas of the bladder, are discussed, and autocrine growth of human solid tumors is also summarized.

Epistatic relationship between Waardenburg syndrome genes MITF and PAX3

Waardenburg syndrome (WS) is a hereditary disorder that causes hypopigmentation and hearing impairment. Depending on additional symptoms, WS is classified into four types: WS1, WS2, WS3 and WS4. Mutations in MITF (microphthalmia-associated transcription factor) and PAX3, encoding transcription factors, are responsible for WS2 and WS1/WS3, respectively. We have previously shown that MITF transactivates the gene for tyrosinase, a key enzyme for melanogenesis, and is critically involved in melanocyte differentiation. Absence of melanocytes affects pigmentation in the skin, hair and eyes, and hearing function in the cochlea. Therefore, hypopigmentation and hearing loss in WS2 are likely to be the results of an anomaly of melanocyte differentiation caused by MITF mutations. However, the molecular mechanism by which PAX3 mutations cause the auditory-pigmentary symptoms in WS1/WS3 remains to be explained. Here we show that PAX3, a transcription factor with a paired domain and a homeodomain, transactivates the MITF promoter. We further show that PAX3 proteins associated with WS1 in either the paired domain or the homeodomain fail to recognize and transactivate the MITF promoter. These results provide evidence that PAX3 directly regulates MITF and suggest that the failure of this regulation due to PAX3 mutations causes the auditory-pigmentary symptoms in at least some individuals with WS1.

Bladder carcinoma cell line KU-19-19-derived cytokines support proliferation of growth factor-dependent hematopoietic cell lines: modulation by phorbol ester, interferon-gamma and interleukin-1 beta

The human bladder carcinoma cell line KU-19-19 synthesizes and secretes hematopoietic growth factors. Conditioned medium (CM) from KU-19-19 stimulated the [3H]thymidine incorporation of growth factor-dependent hematopoietic cell lines. ELISA documented high amounts of granulocyte colony-stimulating factor (G-CSF; > 5 ng/ml); also granulocyte-macrophage CSF (GM-CSF), macrophage-CSF (M-CSF), stem cell factor (SCF), IL-6, and IL-8 were detected in KU-19-19 CM. Pretreatment with phorbol ester, IL-1 beta, or IFN-gamma increased the level of G-CSF, GM-CSF, and M-CSF in KU-19-19 CM. Thus, KU-19-19 represents a reliable source for purification of G-CSF and can easily be used to support proliferation of growth factor-dependent cell lines. The ability to respond to different stimuli suggests that several regulatory pathways may be involved in cytokine production of this bladder carcinoma cell line.

[A case of medullary carcinoma of the thyroid gland: metachronous bilateral metastasis of the neck and mediastinal lymph nodes were treated successfully by staged resection]

This patient, a 52-year-old male, underwent subtotal thyroidectomy on the diagnosis of medullary carcinoma of the thyroid gland in 1980 and postoperative course was uneventful. Since November 1990 he had a persistent diarrhea for 6 months and was admitted to the hospital for the further examination on June 1991. The serum CEA and calcitonine level was very high and chest CT scan findings showed the swelling of right neck and mediastinal lymph nodes. Dissection of the lymph nodes was performed by anterior approach which was gained through a proximal median sternotomy extended into the anterior fourth intercostal space as well as to the base of the neck on the right side. On the pathological examination it was metastasis of medullary carcinoma of the thyroid gland. And 50 months later after second operation he had a persistent diarrhea once again. Left neck and mediastinal lymph node metastasis was detected by chest CT with high serum CEA and calcitonine level. Similarly resection was performed by the same anterior approach on the left side. Irrespective of the extended resection he was free of severe complication; he is still alive 10 months after the third operation without any evidence of recurrence and his current performance status is very good.

Inhibitor effect of apafant on bronchopulmonary responses to platelet activating factor and to antigen in rats

Apafant (4-(2-chlorophenyl)-9-methyl-2-(3-morpholino-3-oxopropyl)-6H-thieno[3,2- f] [1,2,4]triazolo[4,3-a][1,4] diazepine, CAS 105219-56-5, WEB 2086), as a specific platelet activating factor (PAF) antagonist, inhibited PAF-induced increases of bronchial inflation pressure (delta Pi), pulmonary artery perfusion pressure (delta Pp) and microvascular permeability (wet-to-dry lung weight ratios), dose-dependently, in rats. Apafant also inhibited antigen-induced increase of delta pi, delta Pp and microvascular permeability in passively sensitized rats. Ozagrel also inhibited PAF- and antigen-induced increase of delta Pi, delta Pp and microvascular permeability. Apafant almost completely inhibited the increase of intratracheal pressure and microvascular permeability, but incompletely inhibited the increase of pulmonary artery pressure. At 1 microgram/ml, the effects of ozagrel were almost comparable to that of apafant at the same concentration, but the inhibitory effect on intratracheal pressure was less than that of apafant. Apafant inhibited PAF-induced increase in perfusate of thromboxane (TX) B2 and leukotrine C4/D4E4 (LTs), and antigen-induced increase of TXB2, LTs, PAF and histamine. Ozagrel also inhibited the PAF-induced increase of TXB2, but not the increase of LTs. Apafant inhibited antigen-induced increase of TXB2 and LTs more strongly than PAF-induced increase. The order of inhibitory effects of apafant against generation and release of chemical mediators was TXB2, LTs, PAF and histamine. These findings suggest that TXA2, LTs and PAF may contribute to the increase of intratracheal pressure and microvascular permeability, and histamine may contribute to the increase of vascular resistance in rats. Apafant may inhibit bronchopulmonary responses through PAF receptor antagonism. In addition, apafant can be considered to be useful for the treatment of some allergic diseases when the drug is employed in clinical use.

Characterization of density-dependent regulation of the tyrosinase gene promoter: role of protein kinase C

The rate-limiting step in melanogenesis is catalyzed by tyrosinase, a multifunctional enzyme encoded by the albino locus. We have previously reported that depletion of protein kinase C by long-term treatment of B16 mouse melanoma cells with phorbol dibutyrate (PDBu) prevented cell density-dependent melanogenesis. This was accompanied by a lack of induction of tyrosinase protein and mRNA. We report here the effect of PDBu on the functional activity of the mouse tyrosinase promoter by reporter gene assay and its effect on the binding of nuclear proteins from B16 cells to the "M-box" region of the mouse tyrosinase promoter. Short-term PDBu treatment of B16 cells transfected with a mouse tyrosinase promoter-luciferase construct resulted in increased reporter gene activity, while long-term PDBu treatment inhibited reporter gene activity. Using an oligonucleotide containing the M-box and its flanking residues in electrophoretic mobility shift assays, we found a density-dependent change in the pattern of DNA-protein complexes. One complex was found to be negatively regulated by long-term PDBu treatment. Competition experiments with various mutated oligonucleotides demonstrated that both the M-box and flanking residues are important for nuclear protein binding. The complex whose formation was inhibited by long-term PDBu treatment was shown to contain the basic helix-loop-helix leucine zipper protein microphthalmia-associated transcription factor (MITF). These results suggest that chronic PDBu treatment might inhibit tyrosinase expression (and subsequent melanogenesis) by affecting the amount or function of MITF.

Differential diagnosis of primary benign and malignant retroperitoneal tumors

BACKGROUND

Clinical differential diagnosis between malignant and benign tumors is important in order to select a therapeutic strategy for a primary retroperitoneal tumor.

METHODS

The clinical findings and radiological features of 25 patients with primary retroperitoneal tumors were retrospectively evaluated to find those signs that might contribute to the preoperative distinction between benign and malignant tumors.

RESULTS

Of 25 primary retroperitoneal tumors, 15 were benign. This may reflect the increased number of incidentally found small benign tumors. There were significant associations between the presence of symptoms and malignancy (P < 0.05), between irregular margins on imaging and malignancy (P < 0.05) and between the absence of calcification and malignancy (P < 0.05). Malignant tumors were significantly larger than benign tumors (11.45 +/- 1.90 cm vs. 5.31 +/- 0.43 cm). A retroperitoneal tumor scoring system was developed to distinguish primary retroperitoneal benign tumors from their malignant counterparts based on the: 1) maximum diameter equal to or larger than 5.5 cm, 2) presence of symptoms, 3) absence of calcification, 4) presence of irregular margins, and 5) presence of cystic degeneration or necrosis. A significant correlation was found between the incidence of malignant tumors and the total retroperitoneal tumor score (P < 0.05).

CONCLUSION

This study suggests that the size of tumor, the presence of symptoms, irregular margins, and the absence of calcification may be valuable predictors of primary retroperitoneal malignant tumor.

Effects of endocrine therapy on the primary lesion in patients with prostate carcinoma as evaluated by endorectal magnetic resonance imaging

BACKGROUND

Little effort has been made at the quantitative and qualitative evaluation of patients with prostate carcinoma, including downsizing and downstaging of the primary lesion, after conservative therapy. The current study was undertaken to investigate the qualitative and quantitative effects of endocrine therapy on the primary prostate carcinoma using magnetic resonance imaging (MRI).

METHODS

The primary prostate carcinoma was evaluated by endorectal MRI approximately 4 months after the initiation of endocrine therapy in 48 patients with histologically confirmed prostate carcinoma detected by endorectal MRI before therapy.

RESULTS

The volumes of the prostate gland, the carcinoma, and the noncarcinomatous components were reduced to 60.2 +/- 2.7%, 25.5 +/- 2.9%, and 83.2 +/- 6.3% of their pretreatment volumes respectively after endocrine therapy, indicating that the tumors are more susceptible to endocrine therapy than the nontumorous components. The number of prostate carcinomas that demonstrated low signal intensity compared with the normal peripheral zone on T2-weighted images decreased after endocrine therapy and the number of carcinomas with enhancement of T1-weighted contrast-enhanced images increased after therapy. Seven of the 48 patients underwent downstaging after endocrine therapy, based on the endorectal MRI evaluation.

CONCLUSIONS

The results of the current study suggest that downsizing and occasionally downstaging of the carcinoma may occur after endocrine therapy in patients with prostate carcinoma. In addition, the androgen sensitivity of the prostate carcinoma tissue is relatively high compared with the residual noncancerous prostate gland.

Surgically curable and incurable scirrhous carcinomas of the stomach

BACKGROUND AND OBJECTIVES

The purpose of this study was to identify a subgroup of patients with scirrhous carcinoma of the stomach who are more suitable for surgery by analysis of their clinicopathologic characteristics.

METHODS

Seventy-three patients with scirrhous gastric carcinoma who underwent gastrectomy between 1979 and 1994 were included in the study. Clinicopathological characteristics of 5-year survivors and nonsurvivors were compared. A multivariate analysis of various prognostic factors was performed.

RESULTS

The 5-year survival rate was 31.4%; 78% (28/36) of nonsurvivors died of malignant ascites and only 8% (3/36) died of hepatic or lung metastasis. When clinicopathologic parameters of 5-year survivors and nonsurvivors were compared, age, tumor size, macroscopic appearance, pT, pN, pM, stage, peritoneal lavage cytology, residual tumor, extent of gastric resection, operation time, volume of blood loss, and transfusion were significantly different. By the multivariate analysis, residual tumor, pathological depth of tumor infiltration, blood transfusion, and histological type were the independent prognostic factors.

CONCLUSIONS

The prognosis of scirrhous carcinoma of the stomach is mainly determined by the depth of penetration and curability. In order to obtain better survival, early detection of tumor while it is limited to T2 stage appeared most important. Aggressive surgery would be indicated for T3 tumors, but in the case of T4 tumors, extent of operation should be determined by other factors such as extent of nodal metastasis or presence of distant metastasis.

Thyroxine-binding globulin and thyroid hormones after resection of hepatocellular carcinoma

OBJECTIVES

Some human hepatocellular carcinomas (HCCs) produce thyroxine-binding globulin (TBG). High serum TBG levels in such patients may be associated with increased thyroxine (T4) levels. This study aimed to elucidate the serum TBG and thyroid hormone profile in Japanese patients with HCC, to compare the difference between TBG-producing and -nonproducing HCCs, and to investigate the changes in serum TBG level and the thyroid hormone profile after removal of the tumor.

METHODS

The 40 subjects included 20 patients with HCC, 10 healthy controls, and 10 operative controls. Serum TBG, 3,5,3'-triiodothyronine (T3), T4, and free T4 were measured serially for 4 wk after resection of HCC in 16 patients and after control operations in 10 patients. Assay methods were a radioimmunoassay for TBG and enzyme immunoassays for T3, T4, and free T4.

RESULTS

Values higher than the mean +/- 2 SD of controls were considered abnormally high. Of patients with HCC, 60% had abnormally high TBG values, 65% had abnormally high T3 values, 39% had abnormally high T4 values, and 6% had abnormally high free T4 values. The mean levels of TBG and T3 were significantly higher than those in healthy controls, but no difference was found for T4 and free T4 levels. There were no significant differences in various clinicopathological factors between patients with high TBG levels and those with normal TBG levels. After resection of HCC, serum TBG decreased significantly in patients with high TBG levels but not in those with normal TBG levels.

CONCLUSIONS

This study shows that >50% of HCCs in Japanese patients produce TBG; removal of the tumor reduces serum TBG in such cases.

Studies directed toward a mechanistic evaluation of aromatase inhibition by androst-5-ene-7,17-dione. Time-dependent inactivation by the 19-nor and 5 beta, 6 beta-epoxy derivatives

To gain further insight into the mechanism for inactivation of aromatase by androst-5-ene-7,17-dione (1) and its 19-nor analog 4, 10 beta-oxygenated steroids 5 and 6, delta 1(10)-steroid 7, and 19-oxo-5 beta,6 beta-epoxy compound 8 were synthesized and tested for their ability to inhibit aromatase in human placental microsomes. All of the steroids studied inhibited the enzyme in a competitive manner with apparent Ki values ranging from 1.1 to 35 microM. The delta 1(10)-compound 7 was the most potent inhibitor among them. All of the inhibitors caused a time-dependent inactivation of aromatase in the presence of NADPH in air with the kinact values ranging from 0.036 to 0.190 min-1. The substrate androstenedione protected the inactivation, but a nucleophile, L-cysteine, did not, in each case. In contrast, each inhibitor did not cause the time-dependent inactivation in the absence of NADPH. These results show that the 5 beta,6 beta-epoxide 8 and/or the dienone 7 are not a reactive electrophile involved in the irreversible binding to the active site of aromatase during the mechanism-based inactivation caused by the suicide substrates 1 and/or 4.

Clinicopathological features of superficial squamous cell carcinoma of the esophagus

BACKGROUND

The depth of penetration is the crucial factor determining the prognosis of esophageal carcinoma patients. Patients with superficial esophageal carcinoma have a significantly favorable clinical course compared with those with advanced cancers. The outcome for patients with mucosal cancer is excellent with a 5-year survival rate exceeding 80%. On the other hand, submucosal cancer often metastasizes to lymph nodes or other organs, and the prognosis of these patients is far from satisfactory.

METHODS

Among 165 patients with squamous cell carcinoma of the esophagus, surgically resected between December 1979 and April 1995, 30 patients (18.2%) had superficial esophageal carcinoma (SEC) confined to the epithelium, lamina propria mucosa, or submucosa. Disease profile and clinicopathological characteristics of these 30 patients were studied.

RESULTS

The incidence of SEC has increased from 6.3% (2 of 32) in the first 5-year period (1979 to 1984) to 27.4% (20 of 73) in the recent 5-year period (1991 to 1995). Subjective symptoms were present in 2 (13.3%) with 15 mucosal cancers and in 4 (26.7%) with 15 submucosal cancers. The remaining 24 patients (80%) had no subjective symptoms. Twenty-two patients (73.3%) were diagnosed to have the lesions by endoscopic examination at the time of screening for gastric problems, and only 3 were detected by gastrointestinal series. None of the 15 patients with mucosal cancer had lymphatic invasion, venous invasion, or lymph node metastasis. On the other hand, in those with submucosal cancers, 9 (60%) had lymphatic invasion, 5 (33.3%) venous invasion, and 8 (53.3%) lymph node metastases. Twenty-two patients are alive without recurrence. The 3- and 5-year survival rates are 86.7% and 86.7% for patients with mucosal cancer and 72.2% and 65.0% for those with submucosal cancer, respectively.

CONCLUSION

Esophagectomy with wide lymphadenectomy should be carried out for submucosal cancer, whereas esophagectomy with moderate lymphadenectomy can be preferred for mucosal cancer.

Overexpression of metallothionein correlates with chemoresistance to cisplatin and prognosis in esophageal cancer

The aim of this study was to determine the correlation of metallothionein (MT) expression with resistance to cisplatin and to identify prognostic factors in esophageal cancer. Immunostaining for MT was performed on the specimens of squamous cell carcinoma of the esophagus resected from 68 patients with curative intent. The expression of MT was evaluated in terms of clinicopathologic variables, effect of cisplatin, and the patients' survival. Overexpression of MT in the tumor was found in 70.6% of the patients. Stage III and IV tumors were more common in MT-positive tumors (p = 0.0282) but there was no difference in other clinicopathologic variables between MT-positive and MT-negative groups. Stage, cisplatin therapy, and tumor length were the independent prognostic indicators by multivariate analysis. Among 43 patients treated with cisplatin, the 5-year survival rate was 56% for MT-negative and 26% for MT-positive patients (p = 0.0277). In the MT-negative patients, multivariate analysis revealed that curability, stage, cisplatin therapy, and tumor length were the independent prognostic factors. These findings suggest that MT expression in squamous cell carcinoma of the esophagus is a major determinant of the chemoresistance to cisplatin and may be a predictor of poor prognosis.

Lck-independent triggering of T-cell antigen receptor signal transduction by staphylococcal enterotoxins

Superantigens (SAgs) activate T-cells in a manner specific to the Vbeta region of the T-cell antigen receptor. Stimulations by SAgs provoke drastic T-cell activation that leads to programmed cell death or the anergic state of responding cells. To characterize the signal transduction pathway initiated by SAgs, mutant lines derived from the human leukemic T-cell line Jurkat were tested for their reactivities against prototypic SAgs, staphylococcal enterotoxins. The J.CaM1.6 cell line, which lacks Lck expression and lost reactivity against T-cell antigen receptor-mediated stimulation, was activated by staphylococcal enterotoxins in a manner indistinguishable from the Jurkat cell line. In contrast, the J.45. 01 cell line, which lacks expression of functional CD45, showed severely impaired reactivity. The role of Lck appears to be replaced by another Src family protein-tyrosine kinase, Fyn. In J.CaM1.6 cells, Fyn was rapidly phosphorylated and activated after staphylococcal enterotoxin treatment. The kinase-inactive mutant of Fyn significantly suppressed the reactivity against staphylococcal enterotoxin E in J.CaM1.6 cells, and the expression of the active form of Fyn reconstituted reactivity against staphylococcal enterotoxin E in J.45.01 cells. These results demonstrate that SAgs activate T-cells in an Lck-independent pathway and that Fyn plays a critical role in the process.

High-intensity focused ultrasound energy for benign prostatic hyperplasia: clinical response at 6 months to treatment using Sonablate 200

We evaluated the safety and efficacy of high-intensity focused ultrasound (HIFU) using a modified Sonablate 200 and compared the clinical response with that of the prototype Sonablate at 6 months after treatment. Since 1995, 35 patients ages 66 +/- 7 years underwent HIFU with the Sonablate 200 for symptomatic benign prostatic hyperplasia (BPH) under low spinal anesthesia. The estimated prostatic volume was 40.4 +/- 4.8 cc before treatment. A silicon-coated 16F latex catheter was indwelling during determination of the therapy zone and treatment so that critical tissue at the midline was thoroughly treated. Twenty-two patients were analyzed with complete 6-month follow-up data. Side effects were transient urinary retention in four of these patients, hematuria in five, and hematospermia in eight. Peak urinary flow rate increased from 7.4 +/- 4.0 mL/sec to 11.4 +/- 4.0 mL/sec (P < 0.001) (54% increase). During the same period, the mean International Prostatic Symptom Score decreased from 20.4 +/- 7.1 to 9.0 +/- 7.5 (P < 0.001) (56% decrease). Quality of Life score improved from 5.4 +/- 0.6 to 2.4 +/- 1.3 (P < 0.001). Magnetic resonance imaging by means of an endorectal surface coil revealed significant coagulative necrosis areas in the periurethral gland at 1 month on T2-weighted images. These data demonstrate that HIFU for BPH using the Sonablate 200 produced a better clinical response than the prototype Sonablate and is expected to provide long-term durability of the response.

Aromatase inactivation by a suicide substrate, androst-5-ene-4,7,17-trione: the 5beta,6beta-epoxy-19-oxo derivative, as a possible reactive electrophile irreversibly binding to the active site

In order to understand the mechanism involved in the aromatase inactivation by androst-5-ene-4,7,17-trione (4), a suicide substrate of aromatase, 5beta,6beta-epoxyandrosta-4,7,17,19-tetraone (6) was synthesized as a candidate for a reactive electrophile involved in irreversible binding to the active site of aromatase upon treatment of 19-oxo-5-ene steroid 5 with hydrogen peroxide in the presence of NaHCO3. The epoxide 6 was a competitive inhibitor of human placental aromatase (Ki = 34 microM); moreover, it inactivated the enzyme in an active-site-directed manner in the absence of NADPH (Ki = 36 microM, a rate constant for inactivation (k(inact)) = 0.027 min(-1)). NADPH stimulated the inactivation rate, but the substrate androst-4-ene-3,17-dione blocked the inactivation. A nucleophile, L-cysteine, did not cause a significant change in the inactivation. When both the epoxide 6 and its 19-methyl analog 7 were subjected separately to a reaction with N-acetyl-L-cysteine in the presence of NaHCO3, the 19-oxo compound 6 disappeared from the reaction mixture more rapidly (t1/2 = 6.0 min) than the 19-methyl analog 7 (t1/2 = 16 min). On the basis of these results, it is suggested that the 5beta,6beta-epoxy-19-oxo steroid 6 may be the reactive electrophile that alkylates a nucleophilic residue of the amino acid of the active site.

Clinical experience with incidentally discovered pheochromocytoma

PURPOSE

We reviewed 17 resected pheochromocytomas comprising 7 from symptomatic patients, and 10 unsuspected and incidentally discovered tumors. We compared various parameters concerning these 2 groups and investigated the features of the incidentally discovered pheochromocytoma.

MATERIALS AND METHODS

Patient gender and age, clinical symptoms and signs, tumor localization, detection methods, findings on imaging studies, urinary catecholamine concentrations, results of metoclopramide stimulation tests, treatments at operation and tumor size were evaluated. Furthermore, we compared the clinically diverse aspects arising between the symptomatic and incidentally discovered pheochromocytomas.

RESULTS

The 24-hour urinary noradrenaline and vanillylmandelic acid levels in the incidental cases tended to be lower than those in the symptomatic cases, while 24-hour urinary dopamine was significantly less (468 +/- 221 compared to 1,558 +/- 899 microg./day, respectively). Typical symptoms of pheochromocytoma were noted in 6 patients (60%) in the incidental tumor group. The incidental cases had a markedly high false-negative rate (71%) as noted by the metoclopramide stimulation test, although the symptomatic cases had a 100% positive rate. On the other hand, the average diameter of incidental tumors was significantly larger than that of the symptomatic lesions (55.5 +/- 19.1 versus 35.9 +/- 12.1 mm., respectively).

CONCLUSIONS

Clinical signs and findings in patients with incidental tumors were weaker than those with symptomatic disease although most incidental tumors functioned. Lower urinary catecholamine values in the incidental tumors were consistent with these results. However, the surgical risk for incidental tumors was the same as that for symptomatic lesions. Therefore, patients with incidentally discovered pheochromocytomas scheduled to undergo surgery should be treated accordingly.

The value of serum carboxyterminal propeptide of type 1 procollagen in predicting bone metastases in prostate cancer

PURPOSE

Carboxyterminal propeptide of type 1 procollagen (P1CP) is believed to be a marker of new bone formation. We investigated the possible application of serum P1CP as a biochemical marker for bone metastases in patients with prostate cancer.

MATERIALS AND METHODS

Prostate specific antigen (PSA), prostatic acid phosphatase (PAP), P1CP and alkaline phosphatase were measured in 136 serum samples from 79 patients with untreated prostate cancer, 29 with stage D2 disease in remission and 28 with progressive stage D2 carcinoma.

RESULTS

Serum P1CP and alkaline phosphatase were significantly elevated in untreated patients with a positive bone scan (278.9 +/- 61.9 ng./ml. and 826.5 +/- 176.3 international units per 1., respectively) compared to those with a negative bone scan (104.2 +/- 4.2 and 200.8 +/- 9.1, respectively, p <0.05). The areas under receiver operating characteristics curves were 0.86 for P1CP, 0.87 for alkaline phosphatase, 0.88 for PSA and 0.85 for PAP. The best accuracy rates for P1CP, alkaline phosphatase, PSA and PAP to predict bone lesions were 84, 87, 86 and 84%, respectively. P1CP provided a greater specificity and positive predictive value. These serum markers correlated significantly with the extent of disease on bone scan (p <0.05). The incidence of positive serum P1CP and alkaline phosphatase decreased significantly in response to endocrine therapy in patients with bone metastasis, and increased progressively in association with progression of the tumor (p <0.05) parallel to PSA and PAP.

CONCLUSIONS

These findings suggest that serum P1CP is a useful indicator for predicting bone metastases.

Two components of transmitter release in retinal bipolar cells: exocytosis and mobilization of synaptic vesicles

Ca2+-transmitter release coupling was examined using bipolar cells with large presynaptic terminals dissociated from the goldfish retina. Presynaptic Ca2+ current (I(Ca)) was recorded under the whole-cell voltage clamp. Release of excitatory amino acid transmitter was simultaneously monitored as the current through N-methyl-D-asperate (NMDA) receptors of reporter cells or as the membrane capacitance (C(m)) change associated with exocytosis. When I(Ca) was activated by a long depolarizing pulse, a double-peaked transmitter-induced current (I(tr)) was elicited in reporter cells. The rapid component of I(tr) was evoked immediately after the onset of depolarization, and was affected only slightly by intracellularly applied Ca2+ chelators. The delayed slow component of I(tr) was elicited during depolarization once a fixed amount of Ca2+ was accumulated in presynaptic terminals, and its appearance was suppressed or retarded by Ca2+ chelators. Two components of transmitter release were also recognized by monitoring C(m) changes elicited by the activation of I(Ca). These results suggest that bipolar cells have at least two pools of synaptic vesicles; a small, immediately releasable pool and a large releasable pool. The rapid and the delayed slow components of transmitter release may reflect exocytosis and mobilization of synaptic vesicles, respectively.

Electrophysiological characterization of cultured hepatic stellate cells in rats

This study aimed to examine electrophysiological properties of cultured rat hepatic stellate cells (HSCs) using the whole cell configuration of patch-clamp technique. At least three different current components were identified. First, when the membrane was depolarized to voltages more positive than -40 mV, a transient outward K+ current was evoked. Second, membrane hyperpolarization below -60 mV evoked a sustained and inward-rectifying K+ current. The third component was a current flowing outward, which was activated when the cell was depolarized more positively than 0 mV. The channel for this current allowed Na+, K+, and Cl- to pass nonspecifically, suggesting the presence of hemi gap-junctional channel. Furthermore, a laser photobleaching technique revealed the presence of gap junctions between adjacent HSCs. A voltage-gated Ca2+ current, which is known to occur in smooth muscle cells, was searched for but was not detectable. These results suggest that membrane potential of HSCs is determined specifically by the two distinct K+ channels and by an intercellular mechanism involving gap-junctional communication.