Regulation of histone acetyltransferases p300 and PCAF by the bHLH protein twist and adenoviral oncoprotein E1A

Histone acetyltransferases (HAT) play a critical role in transcriptional control by relieving repressive effects of chromatin, and yet how HATs themselves are regulated remains largely unknown. Here, it is shown that Twist directly binds two independent HAT domains of acetyltransferases, p300 and p300/CBP-associated factor (PCAF), and directly regulates their HAT activities. The N terminus of Twist is a primary domain interacting with both acetyltransferases, and the same domain is required for inhibition of p300-dependent transcription by Twist. Adenovirus E1A protein mimics the effects of Twist by inhibiting the HAT activities of p300 and PCAF. These findings establish a cogent argument for considering the HAT domains as a direct target for acetyltransferase regulation by both a cellular transcription factor and a viral oncoprotein.

Lymphangiosis as a predictor of outcome in patients with primary diffusely infiltrative adenocarcinoma of the colon and rectum

OBJECTIVE

To investigate the relationships between outcome and clinicopathological factors, DNA flow cytometrical characteristics, and postoperative adjuvant therapy in patients with primary diffusely infiltrative colorectal adenocarcinoma.

DESIGN

Inception cohort study.

SETTING

A medical center that offers a mixture of primary, secondary, and tertiary care services.

PATIENTS

Among 7035 patients undergoing resection of primary colorectal adenocarcinoma from 1980 to 1996, 37 patients with a pathological diagnosis of primary diffusely infiltrative tumor were selected. All patients had received regular follow-up until February 28, 1998, or until death.

MAIN OUTCOME MEASURES

Cancer-specific survival compared by log-rank test and Cox regression model.

RESULTS

Univariate analyses revealed tumor stage (stages II-III vs. stage IV, P = .01) and severity of lymphangiosis (absent/mild vs. moderate/severe, P = .04) were significant in predicting outcome. A proliferative index of greater than 20% was insignificant (P = .08) in predicting outcome. In a Cox regression model, TNM stage and lymphangiosis were independently correlated with a worse outcome. When compared with tumors having less severe lymphangiosis, the odds ratio of death due to cancer in cases of tumors with moderate to severe lymphangiosis was 2.4 (95% confidence interval, 1.0-5.6; P = .05).

CONCLUSION

Lymphangiosis and TNM stage were independently predictive of outcome in patients with primary diffusely infiltrative colorectal cancer.

Polyamine depletion is associated with an increase in JunD/AP-1 activity in small intestinal crypt cells

Activator protein 1 (AP-1) is a group of dimeric transcription factors composed of protooncogene (Jun and Fos) subunits that bind to a common DNA site, the AP-1 binding site. The proteins of c-Jun, JunB, and Fos are essential for initiation of the cell cycle. Conversely, the activation of the junD gene slows cell growth in some cell types. The current study tests the hypothesis that polyamines influence cell growth by altering the balance of positive and negative Jun/AP-1 activities in intestinal epithelial cells. Studies were conducted in the IEC-6 cell line derived from rat small intestinal crypt cells. Administration of alpha-difluoromethylornithine (DFMO), a specific inhibitor for polyamine synthesis, for 4 and 6 days completely depleted cellular polyamine levels, while AP-1 binding activity was significantly increased. Spermidine, when given together with DFMO, restored AP-1 binding activity toward normal. The increased AP-1 complexes in polyamine-deficient cells were dramatically supershifted by the anti-JunD antibody but not by antibodies against c-Jun, JunB, or Fos proteins. There were significant increases in JunD mRNA and protein in DFMO-treated cells, although expression of the c-fos, c-jun, and junB genes decreased. The increase in JunD/AP-1 activity in DFMO-treated cells was associated with a significant decrease in cell division. Exposure of control quiescent cells to 5% dialyzed serum increased c-Jun/AP-1 but not JunD/AP-1 activities. DFMO prevented the stimulation of c-Jun/AP-1 activity induced by 5% dialyzed serum. These results indicate that 1) polyamine depletion is associated with an increase in AP-1 binding activity and 2) the increase in AP-1 activity in the DFMO-treated cells was primarily contributed by an increase in the JunD/AP-1. These findings suggest that polyamines regulate cell growth at least partially by modulating the balance of positive and negative Jun/AP-1 activities in the intestinal mucosa.

The role of pulmonary inflammation in the development of pulmonary hypertension in newborn with meconium aspiration syndrome (MAS)

1. There was no clear correlation between the tracheal aspirate cytokines and the elevation of pulmonary arterial pressure in newborn piglets with MAS. The use of dexamethasone significantly suppressed tracheal aspirate cytokines but did not significantly alter pulmonary arterial pressure. Dexamethasone significantly increased the cardiac stroke volume and blood pressure. 2. Early dexamethasone therapy (< 12 hrs) for one week in infants with MAS significantly improved pulmonary ventilation and facilitated weaning from mechanical ventilation. 3. The mechanisms for the improvement in cardiopulmonary status following early dexamethasone therapy in MAS remain unclear. An overall improvement in cardiac hemodynamics, along with a significant decrease in lung inflammation may be responsible for the improvement.

A huge pancreatic cystic adenoma misdiagnosed as an ovarian cyst

Pancreatic cyst mimicking an ovarian cyst ultrasonographically has not yet been reported. We report an elderly woman with such a huge pancreatic cyst whose initial presentation was low abdominal pain. Ultrasound showed a hypoechoic cyst measuring 13.6 x 13.2 x 11.8 cm occupying pelvic cavity. She received laparotomy under the impression of ovarian cyst. Interestingly, the cyst was found to have originated from the pancreas. Total cyst excision was performed and pathologic report was pancreatic microadenoma. The patient's postoperative course was unremarkable.

Deficient hydrophilic lung surfactant proteins A and D with normal surfactant phospholipid molecular species in cystic fibrosis

Chronic bacterial colonization of the lungs, with an excessive inflammatory response, is the major cause of morbidity and mortality in cystic fibrosis. Lung surfactant exhibits a spectrum of potential immunomodulatory properties: phospholipid components inhibit cellular inflammatory responses, whereas the hydrophilic surfactant proteins A (SP-A) and D (SP-D) are integral components of the innate host defense response of the lungs against bacterial infection. Consequently, alteration to the relative proportions of lung surfactant components may alter the susceptibility of the lungs to bacterial colonization. In this study, bronchoalveolar lavage (BAL) samples were collected at diagnostic fiberoptic bronchoscopy from 11 control children, 13 children with cystic fibrosis, and 11 children with acute lung infection. Electrospray ionization mass spectrometry analysis demonstrated negligible changes to the molecular species or total BAL concentrations of phosphatidylcholine, phosphatidylglycerol, or phosphatidylinositol among the three subject groups. In contrast, median SP-A concentration was decreased (P < 0.001) in the cystic fibrosis group (2.65 microg/ml) compared with control (12.35 microg/ml) and infection (9.76 microg/ml) groups. Median SP-D was also decreased (P < 0.05) in the infection (12.17 ng/ml) compared with the control group (641 ng/ml), and was below assay limits for the majority of cystic fibrosis children (P < 0. 001). This dramatic decrease of hydrophilic surfactant proteins in the presence of normal surfactant phospholipid may be one mechanism underlying the relative ineffectiveness of the cellular inflammatory response in killing invading bacteria in the lungs of patients with cystic fibrosis.

Diurnal melatonin and cortisol secretion profiles in medicated schizophrenic patients

Although melatonin and/or cortisol secretions have been suggested as markers for both circadian and noradrenaline dysfunctions in psychiatric illnesses, especially in affective disorders, studies of melatonin and cortisol in schizophrenic patients are rare. We evaluated the circadian profiles of melatonin and cortisol secretion in schizophrenic patients and control subjects. A total of 21 medicated Taiwanese male paranoid schizophrenic inpatients (mean age, 27.3 +/- 7.2 yr) and 21 age- and sex-matched controls underwent 24-hour neuroendocrine screening. Melatonin and cortisol concentrations were measured at 2-hour intervals from 0800 h to 2200 h, and at 1-hour intervals from 2300 h to 0700 h. The standard dexamethasone suppression test was performed the next day to provide an index of hypothalamic-pituitary-adrenal axis (HPA) function. The results showed that the circadian rhythm of plasma melatonin secretion was disrupted in schizophrenics compared with controls, whereas the 24-hour profile of plasma cortisol was preserved. The melatonin to cortisol ratio was significantly higher in control subjects than in schizophrenic patients. Results of the dexamethasone suppression tests indicated that there were no functional changes in the HPA axis in schizophrenic patients. Five drug-naive schizophrenic patients studied simultaneously, but whose data were not included in the above analyses, had results consistent with those of the maintenance-medicated patients. Our findings suggest the presence of abnormal melatonin metabolism in Taiwanese schizophrenics, which may possibly be related to the pathophysiologic process itself. However, broader pathogenetic aspects of these neuroendocrine interrelations remain to be clarified.

Comparison of the effects of sevoflurane and isoflurane on arterial oxygenation during one lung ventilation

We have compared the effects of sevoflurane and isoflurane on arterial oxygenation, heart rate and mean arterial pressure during one lung anaesthesia in a prospective, crossover study. We studied 28 patients undergoing oesophagogastrectomy, allocated alternatively to one of two groups. Patients in group I/S (n = 14) received 1 MAC (1.1%) of isoflurane in oxygen from induction until the end of 30 min of open chest one lung ventilation (OLV) in the lateral position. This was followed by 1 MAC (2.1%) of sevoflurane in oxygen for the next 30 min of OLV. Patients in group S/I (n = 14) received the two anaesthetic agents in the reverse order. We found no significant difference in arterial oxygenation, heart rate or mean arterial pressure between the two potent inhalation agents. In the subgroup of patients with pulmonary artery catheters (n = 12), we found a significant increase (P < 0.05) in derived shunt during sevoflurane anaesthesia. There was no significant difference in mixed venous saturation and cardiac output. We conclude that during one lung ventilation, the choice between sevoflurane and isoflurane did not significantly influence arterial oxygenation.

Different prognostic effect of postoperative chemoradiation therapy on diploid and nondiploid high-risk rectal cancers

PURPOSE

DNA ploidy has been shown to play a role in the response to cytotoxic therapy in a variety of malignancies, including breast cancer and melanoma. However, the importance of DNA ploidy in rectal cancer is unknown. The aim of the present study was to determine whether ploidy status might be associated with response to postoperative chemoradiation in TNM Stages II to III rectal cancer.

METHODS

This retrospective study analyzed data from 229 patients with TNM Stages II to III rectal cancer who underwent resection between 1979 and 1984. The ploidy status and treatment modalities in relation to outcome were assessed.

RESULTS

The recurrence-free ten-year survival rate was 52.2 percent for patients with diploidy and 50.5 percent for patients with nondiploidy (P = 0.99). The ten-year survival rates for patients with diploidy and patients with nondiploidy were 55 and 19 percent (P = 0.016) in the chemoradiation group, and 51 and 60 percent (P = 0.15) in the nonchemoradiation group, respectively. In the chemoradiation group, DNA nondiploidy was associated with an increased recurrence rate (83.3 vs. 50.0 percent; P = 0.001). The interaction between DNA nondiploidy and chemoradiation remained important in predicting outcome in the Cox regression model. Factors independently correlated with a worse outcome included Stage IIIb (relative risk, 2.9; 95 percent confidence interval, 1.7-5; P = 0.0001), perineural invasion (relative risk, 2.5; 95 percent confidence interval, 1.6-4, P = 0.0001), distal tumor (relative risk, 1.7; 95 percent confidence interval, 1.1-2.7, P = 0.014), and nondiploidy with chemoradiation (relative risk, 2.9; 95 percent confidence interval, 1.2-7.2, P = 0.0213).

CONCLUSIONS

These findings suggest that DNA nondiploidy is inversely correlated with long-term outcome among patients with high-risk rectal cancer receiving chemoradiation.

Ethanol modulates induction of nitric oxide synthase in glial cells by endotoxin

Although ethanol has long been recognized as an immunosuppressant, the effects of ethanol on immune functions in the central nervous system (CNS) have not been well characterized. Glial cells function as immune effector cells within the CNS. Nitric oxide (NO), generated by inducible NO synthase (iNOS) of activated glial cells, appears to participate in the immune defense and the pathogenesis of brain injury and several neurologic diseases. The goal of the present study was to examine the effects of ethanol on NO production and mRNA expression of iNOS following its induction by bacterial endotoxin lipopolysaccharide (LPS) in cultured glial cells. After incubation of mixed glia with LPS for 24 hr, the levels of nitrite in the culture medium were assayed by Griess reaction. We found that LPS (10-500 ng/ml) induced a concentration-dependent increase in the production of NO which was abolished by the selective iNOS inhibitor aminoguanidine. While ethanol treatment (25 to 400 mM, 24 hr exposure) had no direct effect on basal NO production, it significantly suppressed the LPS-induced increase of nitrite levels in a concentration-dependent manner. Using a semiquantitative reverse transcriptase polymerase chain reaction, we found that while ethanol by itself was unable to induce iNOS mRNA, it nevertheless suppressed LPS-induced iNOS mRNA expression. Our results that ethanol had no direct effect on NO production but inhibited LPS-induced NO, indicated an immunomodulatory role by ethanol. These findings suggest that ethanol may ameliorate the consequences of overwhelming NO generation through iNOS induction in glial cells following infection, inflammation or CNS injuries.

Poly-FISH: a technique of repeated hybridizations that improves cytogenetic analysis of fetal cells in maternal blood

Prenatal diagnosis of fetal chromosomal abnormalities using interphase fetal nucleated erythrocytes (FNRBCs) separated from maternal peripheral blood can be technically challenging due to the limited number of FNRBCs available for analysis, the limited number of probes that can be used simultaneously, and low FISH efficiency on the formaldehyde-fixed and immunohistochemically stained interphase FNRBCs. We developed a technique of sequential FISH analysis that involves removal of the previous hybridized probe under denaturing conditions, and rehybridization with different probes to improve FISH efficiency. This technique facilitates the analysis of multiple chromosome-specific probes on the same nuclei. Results from our experiments show that FISH can be performed at least nine times on the same interphase nucleus and at least three different probes can be used simultaneously. Thus, theoretically, at least 24 different chromosomes can be analysed on a single interphase fetal cell isolated from maternal blood. We have termed this technique 'Poly-FISH', and have successfully diagnosed trisomy 21, triploidy, and other chromosome abnormalities in FNRBCs using this technique.

Direct interaction of Jak1 and v-Abl is required for v-Abl-induced activation of STATs and proliferation

In Abelson murine leukemia virus (A-MuLV)-transformed cells, members of the Janus kinase (Jak) family of non-receptor tyrosine kinases and the signal transducers and activators of transcription (STAT) family of signaling proteins are constitutively activated. In these cells, the v-Abl oncoprotein and the Jak proteins physically associate. To define the molecular mechanism of constitutive Jak-STAT signaling in these cells, the functional significance of the v-Abl-Jak association was examined. Mapping the Jak1 interaction domain in v-Abl demonstrates that amino acids 858 to 1080 within the carboxyl-terminal region of v-Abl bind Jak1 through a direct interaction. A mutant of v-Abl lacking this region exhibits a significant defect in Jak1 binding in vivo, fails to activate Jak1 and STAT proteins, and does not support either the proliferation or the survival of BAF/3 cells in the absence of cytokine. Cells expressing this v-Abl mutant show extended latency and decreased frequency in generating tumors in nude mice. In addition, inducible expression of a kinase-inactive mutant of Jak1 protein inhibits the ability of v-Abl to activate STATs and to induce cytokine-independent proliferation, indicating that an active Jak1 is required for these v-Abl-induced signaling pathways in vivo. We propose that Jak1 is a mediator of v-Abl-induced STAT activation and v-Abl induced proliferation in BAF/3 cells, and may be important for efficient transformation of immature B cells by the v-abl oncogene.

Serum vitamin A level in breast cancer patients

Vitamin A or its synthetic analogues are potent in controlling cell differentiation and in preventing epithelial cancer in experimental animals. Although some community-based studies have found that high serum retinol levels in prediagnostic sera were associated with reduced risk for cancer, other reports in humans have not confirmed this finding. This study is to evaluate the preoperative serum vitamin A level in breast cancer patients in Taiwan. The serum specimens were collected from 106 female cases of breast cancer (aged 30 to 70 years), 32 female cases of benign breast disease (aged 29 to 57 years), and 40 healthy females (aged 22 to 52 years). The serum vitamin A levels were measured by colorimetic analysis. The results showed the mean value of the vitamin A level was 140.4 +/- 65.7 micrograms/dl in the breast cancer group comparing to 145.2 +/- 44.2 micrograms/dl in the benign breast disease group, 144.0 +/- 30.0 micrograms/dl in the control group (P > 0.05). The characteristics of the breast cancer group were analyzed and they revealed that serum vitamin A levels did not bear statistically significant differences in age, duration, steroid receptor, tumor size and menopausal state. (P > 0.05) In conclusion, the serum vitamin A levels were not decreased in early breast cancer patients. The serum vitamin A levels were significantly decreased in the metastatic breast cancer group, especially in liver metastatic women. (P < 0.05). Postoperative vitamin A supplement may have potential benefit to metastatic breast cancer patients.

Detection of ethanol consumption by ELISA assay measurement of acetaldehyde adducts in murine hair

Acetaldehyde (AA), a principal metabolite of ethanol, reacts with proteins to form protein-AA adducts in vivo and in vitro. We studied three different protein-AA adducts produced in vitro, as well as hair keratin-AA adducts from ethanol-fed and/or cocaine-injected mice. An enzyme linked immunosorbent assay (ELISA) was developed that detected the stable protein-AA adducts in protein isolated from hair. Cocaine injection had little effect on hair AA adduct formation. The indirect ELISA assay showed significantly increased levels of keratin-AA adducts in hair from mice fed ethanol for 8 weeks. Hair collection was noninvasive and the AA-protein adducts were stable. Therefore, this indirect ELISA assay could be further developed as a biochemical parameter for alcoholism in the clinical setting.

Close correlation between telomerase expression and adenomatous polyp progression in multistep colorectal carcinogenesis

To investigate the role of telomerase in the multistep colorectal carcinogenesis, we examined telomerase activity in 31 adenomatous polyps and 22 paired cancer-normal mucosa specimens from non-hereditary nonpolyposis colorectal cancer patients. Telomerase activity was detected in 18% of normal mucosa, 16% of small (<1.0 cm) polyps, 20% of intermediate polyps, 71% of large (>2.0 cm) polyps, and 96% of adenocarcinoma samples (P for trend, <0.0001). High-level enzyme activities were seen in none of the normal mucosa, 5% of small polyps, 20% of intermediate polyps, 43% of large polyps, and 73% of adenocarcinoma samples (P for trend, <0.0001). These data indicate telomerase reactivation occurs with adenomatous polyp progression in multistep colorectal carcinogenesis.

Endoscopic ultrasonography for preoperative locoregional staging and assessment of resectability in gastric cancer

We performed a prospective study from November 1989 to December 1996 to assess the accuracy of endoscopic ultrasonography (EUS) in the locoregional staging and resectability of patients with gastric carcinoma. One hundred and nineteen patients with gastric cancer who received preoperative assessment by EUS underwent subsequent surgery. The endosonographic tumor-node-metastasis (TNM) classification was used for comparison with the histopathologic findings of the resected specimens. The ability of EUS to accurately predict the T stage (depth of tumor invasion) and N stage (involvement of lymph node) was 70% and 65%, respectively. EUS displayed a tendency to overestimate T stage and underestimate N state. The differentiation of early gastric cancer from advanced gastric cancer showed a concordance rate of 89% and underestimation rate of 8% and underestimation rate of 3%. The accuracy of EUS in predicting the stage T1 to T3, which correspond to D0 resectability (no macroscopic or microscopic tumor remains), was 91%. In conclusion, these results revealed EUS as a valuable tool for evaluating the local staging and resectability of gastric cancer. We suggest that EUS should be introduced in the preoperative assessment of patients with gastric cancer.

The SH2-containing adapter protein GRB10 interacts with BCR-ABL

Bcr-Abl is an oncogenic tyrosine kinase expressed in tumor cells of CML and a subset of ALL which in its unregulated and activated state is thought to cause cell transformation and leukemia. Bcr-Abl contains several autophosphorylation sites which serve as potential docking sites for SH2-containing signaling molecules. Mutational analysis has indicated that these autophosphorylation sites play a critical role in the transforming capability of Bcr-Abl. It has been shown that the SH2-containing adapter protein Grb2 binds to the autophosphorylation site Tyr(p)177 whereby it couples Bcr-Abl to the Ras pathway. The biological consequences of this interaction, however, are presently unclear. A Tyr177-mutated Bcr-Abl which lacks the ability to interact with the Grb2-SH2 domain still transforms myeloid cells and generates tumors in nude mice. We performed a yeast two-hybrid screen to identify signaling proteins which bind to distinct Bcr-Abl autophosphorylation sites. Autophosphorylation of Bcr-Abl in yeast was accomplished by using the DNA binding protein LexA which permits dimerization and crossphosphorylation of the fused bait. Using a LexA-Bcr-Abl full length fusion protein as bait, we identified several SH2-containing proteins. Among them we confirmed molecules already shown by others to interact with Bcr-Abl, in vivo, including Grb2, PI-3-kinase and Crk indicating that dimerization in yeast leads to autophosphorylation of tyrosine residues crucial for Bcr-Abl signaling in vivo. More importantly, we identified the SH2-containing protein Grb10 as a new binding partner for Bcr-Abl. This binding occurs in a phosphotyrosine-dependent manner at Bcr sites of Bcr-Abl. Both Abl and Bcr alone, as well as a kinase-defective Bcr-Abl, failed to interact with Grb10 in yeast. Mutational analysis uncovered a new SH2 binding site in Bcr-Abl located between Bcr aa242-446, which is different from the Grb2 binding site. Binding could be demonstrated in vitro and also in vivo as shown by co-immunoprecipitation analysis in CML cells. Using a temperature sensitive Bcr-Abl stably overexpressed in hematopoetic cells, we demonstrated that complex formation of Grb10 with Bcr-Abl was kinase activation-dependent in vivo. Notably, a Bcr-Abl mutant protein (Bcr/1-242-Abl) which lacks the ability to interact with Grb10 partially alleviated IL-3 dependence of Ba/F3 cells, indicating that the Grb10/Bcr-Abl interaction is important for Bcr-Abl-induced IL-3 independence of Ba/F3 cells. In addition, the Bcr/1-242-Abl mutant has a reduced capacity to induce focus formation in fibroblasts.

Transmembrane neuregulins interact with LIM kinase 1, a cytoplasmic protein kinase implicated in development of visuospatial cognition

The neuregulins are receptor tyrosine kinase ligands that play a critical role in the development of the heart, nervous system, and breast. Unlike many extracellular signaling molecules, such as the neurotrophins, most neuregulins are synthesized as transmembrane proteins. To determine the functions of the highly conserved neuregulin cytoplasmic tail, a yeast two-hybrid screen was performed to identify proteins that interact with the 157-amino acid sequence common to the cytoplasmic tails of all transmembrane neuregulin isoforms. This screen revealed that the neuregulin cytoplasmic tail interacts with the LIM domain region of the nonreceptor protein kinase LIM kinase 1 (LIMK1). Interaction between the neuregulin cytoplasmic tail and full-length LIMK1 was demonstrated by in vitro binding and co-immunoprecipitation assays. Transmembrane neuregulins with each of the three known neuregulin cytoplasmic tail isoforms interacted with LIMK1. In contrast, the cytoplasmic tail of TGF-alpha did not interact with LIMK1. In vivo, neuregulin and LIMK1 are co-localized at the neuromuscular synapse, suggesting that LIMK1, like neuregulin, may play a role in synapse formation and maintenance. To our knowledge, LIMK1 is the first identified protein shown to interact with the cytoplasmic tail of a receptor tyrosine kinase ligand.

Inhibition of DNA synthesis by RB: effects on G1/S transition and S-phase progression

The retinoblastoma tumor suppressor protein, RB, is a negative regulator of cell proliferation. Growth inhibitory activity of RB is attenuated by phosphorylation. Mutation of a combination of phosphorylation sites leads to a constitutively active RB. In Rat-1 cells, the phosphorylation-site-mutated (PSM)-RB, but not wild-type RB, can inhibit S-phase entry. In PSM-RB-arrested G1 cells, normal levels of cyclin E and cyclin E-associated kinase activity were detected, but the expression of cyclin A was inhibited. The ectopic expression of cyclin E restored cyclin A expression and drove the PSM-RB expressing cells into S phase. Interestingly, Rat-1 cells coexpressing cyclin E and PSM-RB could not complete DNA replication. Microinjection of cells that have passed through the G1 restriction point with plasmids expressing PSM-RB also led to the inhibition of DNA synthesis. The S-phase inhibitory activity of PSM-RB could be attenuated by the coinjection of SV40 T-antigen, adenovirus E1A, or a high level of E2F-1 expression plasmids. However, the S-phase inhibitory activity of PSM-RB could not be overcome by the coinjection of cyclin E or cyclin A expression plasmids. These results reveal a novel role for RB in the inhibition of S-phase progression that is distinct from the inhibition of the G1/S transition, and suggest that continued phosphorylation of RB beyond G1/S is required for the completion of DNA replication.

Inhibitory effect of pulmonary surfactant proteins A and D on allergen-induced lymphocyte proliferation and histamine release in children with asthma

The role of pulmonary surfactant proteins in the pathogenesis of airway inflammation and the impact on asthma has not been elucidated. This study was designed to examine the effect of surfactant proteins A (SP-A) and D (SP-D) on phytohemagglutinin- (PHA) and mite allergen Dermatophagoides pteronyssinus (Der p)-induced histamine release and the proliferation of peripheral blood mononuclear cells (PBMC) in children with asthma in stable condition (n = 21), asthmatic children during acute attacks (n = 9), and age-matched control subjects (n = 7). The results show that SP-A and SP-D were able to reduce the incorporation of [3H]thymidine into PBMC in a dose-dependent manner. In addition to the intact, native SP-A and SP-D proteins, a recombinant peptide composed of the neck and carbohydrate recognition domain (CRD) of SP-D [SP-D(N/CRD)] was also found to have the same suppressive effect on lymphocyte proliferation. This effect was abolished by the presence of 100 mM mannose (for SP-A) or maltose (for SP-D) in the culture medium, which suggested that the CRD regions of SP-A and SP-D may interact with the carbohydrate structures on the surface molecules of lymphocytes. The inhibitory effects of surfactant proteins on PHA- and Der p-stimulated lymphocyte responses were observed in stable asthmatic children and age-matched control subjects, while only a mild suppression (< 25%) was seen in activated lymphocytes derived from asthmatic children with acute attacks. SP-A and SP-D were also found to inhibit allergen-induced histamine release, in a dose-dependent manner, in the diluted whole blood of asthmatic children. We conclude that both SP-A and SP-D can inhibit histamine release in the early phase of allergen provocation and suppress lymphocyte proliferation in the late phase of bronchial inflammation, the two essential steps in the development of asthmatic symptoms. It appears that SP-A and SP-D may be protective against the pathogenesis of asthma.

Segmental colectomy in the management of colonic inertia

Subtotal colectomy with ileorectostomy has been proposed for the management of colon inertia-type constipation. However, many patients experience frequent bowel movements, watery diarrhea, or both after such a treatment. The purpose of this study is to determine the proper colectomy with which to treat colon dysmotility constipation without the negative side effects of frequent bowel movements, watery diarrhea, or both. Forty idiopathic constipation patients were studied. All of the patients showed a prolonged right or left colon transit time and normal transit time of the sigmoid and rectum. They received different types of colectomies (left, right, and subtotal) according to the distribution or accumulation of markers in the colon. Within 3 months of surgery, all of the patients experienced a dramatic improvement of their symptoms without frequent bowel movements or watery diarrhea. No significant complications developed after surgery. All the patients were followed up for at least 2 years. Most of them (37 cases) still had satisfactory bowel movements and no other constipation symptoms. However, 3 of the 40 cases developed symptoms of constipation 1 1/2 to 2 years after surgery. They all received subtotal colectomy with ileorectal anastomosis subsequently. They reobtained satisfactory bowel movements and experienced a subsidence of other constipation symptoms 3 months later. These results suggest that directed segmental colectomy can improve colonic inertia constipation without the consequence of frequent bowel movements and diarrhea.

Diffuse cavernous hemangioma of the rectum complicated by invasion of pelvic structures. Report of two cases

PURPOSE

We present two cases of diffuse cavernous hemangioma of the rectum that invaded the pelvic structures.

METHODS

Two young women suffering from intermittent rectal bleeding were studied using computed tomography and magnetic resonance imaging.

RESULTS

Beside the rectal hemangioma, computed tomography and magnetic resonance imaging revealed that the pelvic ureter and the iliac vessels were each eroded by the tumor that produced symptoms in these two patients.

CONCLUSION

Computed tomography and magnetic resonance imaging permit direct visualization for tumor staging and also for recognition of any pelvic structure invasion, which facilitate preoperative assessment of diffuse cavernous hemangioma of the rectum.

Mathematical relationships among DNA supercoiling, cation concentration, and temperature for prokaryotic transcription

DNA twist has been proposed to affect transcription from some promoters of Escherichia coli, but involvement of twist has been difficult to test because it cannot be measured in transcription reaction mixtures. However, changes in other factors affect both DNA twist and transcription. These parameters are expected to be related when maximum transcription initiation is considered. In the present work, mathematical relationships among supercoiling, cation concentration, and temperature are derived for prokaryotic transcription initiation. The relationships indicate that as DNA becomes more negatively supercoiled, maximal initiation occurs at a higher cation concentration and at a lower temperature. For example, when superhelical density becomes more negative by 0.0025, a 1.6-fold increase in potassium concentration is predicted to be required to maintain transcription initiation at its maximum rate. Experimental verification of the relationships should provide a useful test of the idea that transcription initiation is sensitive to DNA twist.

Expression of the transforming growth factor-beta gene during growth inhibition following polyamine depletion

Polyamine depletion and cytokine transforming growth factor-beta (TGF-beta) inhibit cell proliferation. The current study tests the hypothesis that polyamine depletion results in growth inhibition by altering expression of the TGF-beta gene in intestinal epithelial cells. Studies were conducted in the IEC-6 cell line derived from rat small intestinal crypt cells. Cells were grown in DMEM in the presence or absence of alpha-difluoromethylornithine (DFMO), a specific inhibitor of polyamine biosynthesis, for 6 and 12 days. Administration of DFMO not only depleted intracellular polyamines but also significantly increased the mRNA levels of TGF-beta. Increased TGF-beta mRNA in DFMO-treated cells was paralleled by an increase in TGF-beta content. Depletion of intracellular polyamines by DFMO had no effect on the rate of TGF-beta gene transcription, as measured by nuclear run-on assay. The half-life of mRNA for TGF-beta in normal cells was approximately 65 min and increased to >16 h in cells treated with DFMO for 6 or 12 days. Exogenous polyamine, when given together with DFMO, prevented the increased half-life of TGF-beta mRNA in IEC-6 cells. TGF-beta added to the culture medium significantly decreased the rate of DNA synthesis and final cell number in normal and polyamine-deficient cells. Furthermore, growth inhibition caused by polyamine depletion was partially but significantly blocked by addition of immunoneutralizing anti-TGF-beta antibody. These results indicate that 1) depletion of intracellular polyamines induces the activation of the TGF-beta gene through posttranscriptional regulation and 2) increased expression of the TGF-beta gene plays an important role in the process of growth inhibition following polyamine depletion.

The effect of portal hypertension on transforming growth factor-alpha and epidermal growth factor receptor in the gastric mucosa of rats

The aim of this study was to evaluate the expression of transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) immunohistochemically in gastric mucosa of portal hypertensive (PHT) and sham-operated rats. PHT was induced experimentally by partial ligation of the portal vein (PVL) in 12 male Wistar rats; another group of 12 rats (control) received sham operations. The severity of macroscopic gastric mucosal lesions and immunoreactivity of TGF-alpha and EGFR were evaluated 14 days following the above procedure. The damage to gross gastric mucosa was found to be significantly greater in the PVL group than the control group (p<0.01). Additionally, the TGF-alpha and EGFR immunoreactivities were significantly more intense in the PVL groups compared to the control (P<0.05). The TGF-alpha and EGFR immunoreactive cells were more prominent around injured mucosa. From these findings, we suggest that locally produced TGF-alpha and EGFR may play an important role in the gastric mucosal repair following PHT to rats.