Molecular analysis of oral lichen planus. A premalignant lesion?

Oral lichen planus (OLP) is a common mucosal condition that is considered premalignant by some, although others argue that only lichenoid lesions with dysplasia are precancerous. To address the question of whether OLP without dysplasia is premalignant, we used microsatellite analysis to examine 33 cases of OLP for allelic loss at nine loci located on chromosomes 3p, 9p, and 17p. Loss of heterozygosity (LOH) on these three arms occurs frequently in oral tumors, and the presence of these alterations in premalignant lesions suggests that they may play an important role in tumor progression. Results were compared with those observed in oral dysplasias (10 mild, 11 moderate, 16 severe/carcinoma in situ), 22 oral squamous cell carcinomas, and 29 reactive lesions. LOH was present in 6% of OLP, 14% of reactive lesions, 40% of mild dysplasia, 46% of moderate dysplasia, 81% of severe dysplasia/carcinoma in situ, and 91% of squamous cell carcinomas. LOH was detected on only a single arm in OLP and reactive lesions but occurred on more than one chromosome in dysplasia and cancer, and the frequency of this multiple loss correlated significantly with increasing degrees of dysplasia and progression into squamous cell carcinoma (P = 0.0028). Although these findings do not support OLP as a lesion at risk for malignant transformation, such results need to be confirmed by use of other genetic markers as OLP may undergo malignant transformation through genetic pathways different from those of oral dysplasia.

Novel perspectives on pituitary and brain angiotensinogen

All the angiotensin peptides originate from angiotensinogen, a glycoprotein synthesized by several tissues, including the brain and the anterior pituitary. In the rat, immunohistochemistry has been used to localize angiotensinogen in gonadotropes and in uncharacterized cells surrounding sinusoids. Both cell types are capable of secreting angiotensinogen in cell culture; only the gonadotropes contain angiotensin II (AngII) and are capable of secreting it in culture. It has been asserted that the perisinusoidal cells are the only source of angiotensinogen for the generation of AngII by gonadotropes. Our current data favor the existence of a complete intracellular renin-angiotensin system (RAS) in gonadotropes and a separate extracellular system which utilizes the high concentration of angiotensinogen from perisinusoidal cells. Furthermore, we postulate that gonadotrope AngII serves mainly reproductive functions, while the proximity of angiotensinogen-secreting cells to folliculostellate cells, and their access to the intercellular sinusoidal and follicular spaces, places the extracellular RAS in a strategic position to affect pituitary growth and the mediation of acute-phase immune responses. In the rat brain, angiotensinogen is expressed by the 16-18th day of fetal life and by areas generally concerned with vasopressor, electrolyte, and fluid homeostasis. Antisense deoxyoligonucleotides to angiotensinogen mRNA lower blood pressure in hypertensive rats and inhibit in vitro growth of neuroblastoma cells, indicating a significant role for angiotensinogen in mitogenic and homeostatic functions. It is commonly agreed that astrocytes express angiotensinogen. Neuronal angiotensinogen has also been demonstrated by immunohistochemistry, as a secretion from neuronal cell cultures, and by reverse-transcriptase polymerase chain reaction. The fate of secreted astrocytic and neuronal angiotensinogen remains obscure. Angiotensinogen is regulated in a tissue-specific manner with smaller or absent responses observed for brain tissue. By using astrocyte and neuronal cultures the actions on angiotensinogen production of growth hormone, IGF-1, inflammatory lipopolysaccharide, and phorbol ester have been examined. Recent observations show that angiotensinogen is regulated positively or negatively by glucocorticoids and that a positive synergism between cAMP and glucocorticoids exists. On the basis of analogous systems for other proteins, a scheme involving glucocorticoid receptors, CREB, and AP-1 transcription factors is formulated to explain glucocorticoid-cAMP interactions. These transcriptional interactions may form a significant functional link between the RAS and adrenergic mechanisms.

[En bloc vein resection in the treatment of pancreatic tumors adherent to the superior mesenteric-portal vein confluence]

Contraindication is often considered to pancreaticoduodenectomy for patients with malignant tumors of the pancreatic head. From 1989 through 1995, 15 patients with tumors of the pancreatic head adherent to the superior mesenteric-portal vein confluence (SMPV) underwent pancreaticoduodenectomy with en bloc resection of SMPV. There was no perioperative mortality. Follow-up data showed a mean survival of 17.1 months among 7 deaths, which was significantly longer than an average of 3.8 months among previous 17 patients who abandoned radical resection (P < 0.001). We consider that pancreaticoduodenectomy with en bloc resection of SMPV is feasible in some cases.

Detection of alterations in the levels of neuropeptides and salivary gland responses in the non-obese diabetic mouse model for autoimmune sialoadenitis

The salivary glands of non-obese diabetic (NOD) mice and BALB/c controls were evaluated for the stimulatory effects of the following neuropeptides; substance P (SP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY). Injection of either of the three neuropeptides in combination with the muscarinic-cholinergic agonist pilocarpine increased saliva flow rates in BALB/c mice while there was no observable augmentation to flow rates in pre-diabetic or diabetic NOD mice. Small increases in protein content of the stimulated saliva were observed in the BALB/c group of animals with the injection of any of the above neuropeptides in combination with pilocarpine. In pre-diabetic NOD animals, only VIP and NPY increased the protein content-ratio above pilocarpine alone. Radioimmunoassay determination of neuropeptide concentrations in the submandibular and parotid glands revealed reduced levels of SP with diabetes onset as compared with pre-diabetic NOD or BALB/c mice. The levels of NPY were similar between BALB/c and NOD animals except in the pre-diabetic parotid gland where NPY concentrations were 1.3-fold greater. On the other hand, VIP concentrations were substantially reduced in the submandibular gland of NOD mice, while in the parotid gland neuropeptide levels were evaluated 3.8-fold relative to BALB/c controls. Immunohistochemical staining of the parotid and submandibular glands for SP revealed primarily ductal cell staining which was reduced with diabetes onset in NOD animals. These findings further define the sialoadenitis observed in NOD mice to be due, in part, to a general loss of neurotransmitter responsiveness on the part of salivary gland cells.

Cell cycle control in isoproterenol-induced murine salivary acinar cell proliferation

The eukaryotic cell cycle is a summary of a complex network of signal transduction pathways resulting in both DNA replication and cell division. Cyclin-dependent kinases (CDKs) control the cell cycle in all eukaryotes, whereas other proteins, known as cyclins, act as their regulatory subunits. Chronic injection with isoproterenol (ISO) can induce acinar cell proliferation in rodent salivary glands. Cyclins and CDK proteins from control and ISO-treated murine parotid acinar cells were detected by using Western blotting techniques. By comparing the expression of these cell cycle regulatory kinases in the parotid acinar cell transition from a quiescent state to a hypertrophic state, we found rapid increases in the protein levels of all CDKs, cyclin D and proliferating cell nuclear antigen (PCNA). The highest protein levels for CDKs and cyclins appeared at about 72 hr of ISO stimulation and were coincident with the highest rate of increase in gland wet weight. After 72 hr, the increase of both cell cycle protein and gland wet weight began to subside. By using a co-immunoprecipitation method, the following cell cycle regulators (CDK-cyclin complexes) were detected, CDK4-cyclin D, CDK2-cyclin E, CDK2-cyclin A, and cdc2-cyclin B, along with an increase in kinase activity over control untreated animals. Additionally, we detected significant decreases in the newly isolated CDK inhibitor (CKI) p27kip but not Wee 1 kinase. The increased levels of CKI correlated with a decrease in kinase activity of CDK/cyclin complexes by 144 hr of chronic isoproterenol treatment. Our data suggest that the holoenzymes for cell cycle control (cyclin-CDK complexes) function as a final regulatory mechanism leading to salivary gland acinar cell proliferation. The gradual decline in protein levels of the CDKs and cyclins after 3 days of chronic treatment further indicates that ISO-induced proliferation of parotid acinar cells is self-limiting and non-tumorigenic.

Effects of 7-bromoethoxybenzene-tetrahydropalmatine on voltage-dependent currents in guinea pig ventricular myocytes

AIM

To study the anti-arrhythmic mechanism of 7-bromoethoxybenzene-tetrahydropalmatine (EBP).

METHODS

Whole-cell current and voltage clamp on isolated guinea pig ventricular cells.

RESULTS

EBP 30 mumol.L-1 prolonged APD90 from 430 +/- 47 ms to 514 +/- 61 ms (n = 5, P < 0.05) without effects on the action potential amplitude and resting potential. Delayed outward K+ current and its tail current were blocked by EBP in a concentration-dependent fashion, while EBP did not change the amplitudes of the sodium current, the L type calcium current, and the inwardly rectifying potassium current.

CONCLUSION

The mechanism of anti-arrhythmic action of EBP was to prolong the APD through inhibiting the delayed rectified potassium current.

Effect of levonorgestrel-releasing intrauterine device on hormonal profile and menstrual pattern after long-term use

In the present study 14 women after 6 years' use of levonorgestrel-releasing IUD were investigated for the changes of LH, progesterone (P), estradiol (E2), prolactin (PRL) and serum binding globulin (SHBG) in relation to the levonorgestrel levels throughout a segment of 26-40 days with the aim of comparing the hormonal profiles with those during the first year of use of Lng-IUD. Ultrasound scanning was used to follow the development of follicles along with the RIA measurement of hormones. The results of serum LH, P and E2 showed ovulation in 11 cases with either normal menstrual cycles (5 cases), prolonged or irregular cycles (4 cases) or with amenorrhea for 2-3 years (2 cases). One case showed insufficiency of luteal function and 2 cases showed anovulation but with follicular hyperactivity. Higher percentages of ovulatory cycles (78.5%) were found after 6 years of use. No case of complete suppression of ovulation was found. Anovulatory cycles only constituted 14.3%. Clinically, the development of follicles followed by ultrasound scanning further confirmed the hormonal findings. The persistent enlargement of follicles coincided with high levels of E2. After 6 years of use, the serum levels of levonorgestrel were still maintained at mean levels of 314.26 pmol/L and 470.63 pmol/L in the ovulatory and anovulatory groups, respectively. It is concluded that over two-thirds of the cases have ovulatory cycles after long-term use of Lng-IUD; the contraceptive effect is mainly due to its local action on the endometrium, with much less effect on the ovarian function.

Phorbol ester-induced transcription of an immediate-early response gene by human T cells is inhibited by co-treatment with calcium ionophore

Human T cells require two discrete signals to initiate their proliferation. In Jurkat T cells the first signal can be provided by the phorbol ester TPA and the second by the calcium ionophore A23187. We have isolated a cDNA from Jurkat T cells representing mRNA induced by TPA but inhibited by simultaneous treatment of the cells with antibody, lectin, or A23187. Sequencing revealed identity of the Jurkat clone to a cDNA, termed ETR101, recently isolated from HL60 promyelocytic leukaemia cells and shown to be an immediate early gene expressed upon TPA stimulation of these cells [Shimizu et al.: J Biol Chem 266:12157, 1991]. The gene is also induced very rapidly upon TPA treatment of Jurkat cells and is superinduced by co-treatment with cycloheximide. The predicted amino acid sequence encoded by ETR101 has weak homology to JunB and JunD, therefore it is of some interest that these three genes share the chromosomal localization, 19p13.2. The divergent effects of TPA treatment upon cell proliferation and differentiation in different circumstances allow some speculation about a possible role for the ETR101 gene product upon cellular differentiation.