Sister chromatid exchanges are mediated by homologous recombination in vertebrate cells

Sister chromatid exchange (SCE) frequency is a commonly used index of chromosomal stability in response to environmental or genetic mutagens. However, the mechanism generating cytologically detectable SCEs and, therefore, their prognostic value for chromosomal stability in mitotic cells remain unclear. We examined the role of the highly conserved homologous recombination (HR) pathway in SCE by measuring SCE levels in HR-defective vertebrate cells. Spontaneous and mitomycin C-induced SCE levels were significantly reduced for chicken DT40 B cells lacking the key HR genes RAD51 and RAD54 but not for nonhomologous DNA end-joining (NHEJ)-defective KU70(-/-) cells. As measured by targeted integration efficiency, reconstitution of HR activity by expression of a human RAD51 transgene restored SCE levels to normal, confirming that HR is the mechanism responsible for SCE. Our findings show that HR uses the nascent sister chromatid to repair potentially lethal DNA lesions accompanying replication, which might explain the lethality or tumorigenic potential associated with defects in HR or HR-associated proteins.

Fetal hydrocephalus secondary to intraventricular hemorrhage diagnosed by ultrasonography and in utero fast magnetic resonance imaging. A case report

Although fetal hydrocephalus is commonly detected by prenatal ultrasonographic examination, posthemorrhagic hydrocephalus has rarely been observed in the fetus. We report a case of hydrocephalus secondary to intraventricular hemorrhage (IVH) diagnosed by in utero magnetic resonance imaging (MRI) at 37 + 1 weeks of gestation. Ultrasonography revealed enlargement of the bilateral ventricles and an irregular mass measuring 20 x 12 x 10 mm in the right lateral ventricle. T1-weighted images with two-dimensional fast low-angle shot (2D-FLASH) and T2-weighted images with half-Fourier single-shot turbo spin echo (HASTE) demonstrated that an old hemorrhagic clot existed in the right lateral ventricle of the fetus. Hydrocephalus secondary to IVH was confirmed by postnatal MRI and ventriculoscopy. Fast MRI is especially useful for prenatal diagnosis of fetal brain abnormalities because it minimizes the artifact of fetal movement.

Joint effects of HMG-CoA reductase inhibitors and eicosapentaenoic acids on serum lipid profile and plasma fatty acid concentrations in patients with hyperlipidemia

HMG-CoA reductase inhibitors reduce serum total cholesterol concentrations and the risk of coronary heart disease in patients with hypercholesterolemia. Recently, it has been reported that patients with combined hyperlipidemia are also at risk of coronary heart disease. However, HMG-CoA reductase inhibitor therapy alone does not sufficiently reduce serum triglyceride concentrations. Epidemiological and clinical evidence has shown that fish oil can lower plasma lipid levels, especially triglycerides. Consequently, we investigated the effects of the combination of HMG-CoA reductase inhibitors and eicosapentaenoic acid, a major component of fish oil, on hyperlipidemia. We administered 900-1,800 mg/day of the ethyl ester of eicosapentaenoic acid to patients with hyperlipidemia who had been treated with HMG-CoA reductase inhibitors for 30 +/- 6 months (means +/- SE). Serum total cholesterol and triglyceride concentrations were significantly decreased 3 months after the administration of eicosapentaenoic acid (from 5.63 +/- 0.23 mmol/l to 5.02 +/- 0.20 mmol/l, P < 0.05; from 2.07 +/- 0.41 mmol/l to 1.08 +/- 0.17 mmol/l, P < 0.01, respectively). Serum high-density lipoprotein-cholesterol concentrations were significantly increased after the treatment (from 1.23 +/- 0.12 mmol/l to 1.34 +/- 0.13 mmol/l, P < 0.05). Plasma eicosapentaenoic acid concentrations and the ratio to arachidonic acid in plasma were also significantly increased 3 months after the treatment (from 101.9 +/- 8.1 mg/l to 181.8 +/- 23.9 mg/l, P < 0.001; from 0.640 +/- 0.075 to 1.211 +/- 0.170, P < 0.001, respectively). These results suggested that the combination therapy of HMG-CoA reductase inhibitors and eicosapentaenoic acid was effective for patients with hyperlipidemia.

The effect of left-to-right shunting on coronary oxygenation during extracorporeal membrane oxygenation

BACKGROUND/PURPOSE

Blood perfusion to the coronary artery (CA) during venoarterial (VA) extracorporeal membrane oxygenation (ECMO) was examined to determine whether it was receiving highly oxygenated ECMO blood or desaturated blood from the pulmonary circulation of diseased lungs.

METHODS

In the first experiment, left ventricle output and oxygen saturation in the left ventricle (LV) and CA were measured in dogs placed on VA ECMO. In the second experiment, dogs with an artificial subclavian-pulmonary artery shunt were placed on VA ECMO at 100 mL/kg/min, and oxygen saturation was measured as the shunt flow increased.

RESULTS

Without an artificial shunt, a substantial portion of coronary perfusion was found to be supplied by the left ventricle (54 + 30%), even at a high ECMO flow rate of 100 mL/kg/min and low LV output (22+/-17%) relative to ECMO flow. With a shunt, oxygen saturation in the CA was more than 95%, even when shunt flow was only 7.5% of ECMO flow and output from the left ventricle was less than 25% of the ECMO flow rate.

CONCLUSIONS

These results suggest that an excessive "lung rest" strategy during VA ECMO may produce suboptimal coronary oxygenation possibly leading to myocardial damage. The presence of a small left-to-right shunt may prevent coronary hypoxia.

Influence of increased abdominal pressure on steady-state cardiac performance

The effect of steady-state increases in abdominal pressure (Pab) on cardiac performance was studied in seven acutely instrumented swine with pneumoperitoneum (PP). The animal was placed on volume-preset ventilation, and PP was created by air insufflation. Cardiac output (CO), right atrial (Pra), left atrial (Pla), pericardial (Ppe), and abdominal inferior vena cava pressures (Pivc) were measured while Pab was increased from baseline to 7.5, 15, and 30 mmHg (PP7.5, PP15, and PP30, respectively). Cardiac function curves of the right and left ventricle (RV and LV, respectively) were compared between baseline and PP30. CO presented biphasic changes, with an inital slight increase at PP7.5 followed by a fall at PP30. A significant discrepancy was observed between Pra and Pivc at PP15 and PP30, consistent with development of a "vascular waterfall." Transmural Pla (Pla - Ppe) showed parallel changes with CO, whereas transmural Pra (Pra - Ppe) exhibited a sustained increase. The RV cardiac-function curve was more depressed than was that of the LV at PP30; this suggests an increased RV afterload produced by the elevated airway pressure. These results support the hypothesis that our previously proposed concept of abdominal vascular zone conditions (M. Takata, R. A. Wise, and J. L. Robotham. J. Appl. Physiol. 69: 1961-1972, 1990) is also applicable to steady-state hemodynamic analyses. The abdominal zones appear to play an important role in determining CO, with increases in Pab, by modulating systemic venous return and the LV preload. Simultaneous measurements of Pra and Pivc may provide useful information in the hemodynamic care of patients with elevated Pab.

p16INK4a inactivation is not frequent in uncultured sporadic primary cutaneous melanoma

In an attempt to examine whether the inactivation of p16INK4a is an important early event in the development of sporadic melanoma in vivo, we have systematically analysed 46 uncultured primary cutaneous melanomas. Loss of heterozygosity (LOH) of chromosome region 9p21-22 (where the p16INK4a resides) was detected in 11 tumours (24%) by PCR-based LOH analyses. Direct sequencing of all three exons of the p16INK4a gene in these 11 tumours revealed no somatic mutation although germline mutations which have not been reported previously as common polymorphisms were detected in two patients. Further sequencing analyses of the p16INK4a gene exon 2 in 19 additional tumours with no evidence of LOH on 9p21-22 identified only one heterozygous C- >T mutation at codon 81 altering a proline to a leucine. A sensitive methylation-specific PCR assay did not reveal de novo methylation of the 5'CpG island in exon 1 of the p16INK4a gene in any of the tumours showing 9p21-22 allelic loss or a heterozygous p16INK4a mutation. Complete loss of p16INK4a protein, most likely due to homozygous deletion of the p16INK4a gene, was observed in 6 (15%) out of 39 evaluable cases by immunohistochemical analyses on frozen sections using two different anti-p16INK4a antibodies. The results show that inactivation of p16INK4a is not as frequent in primary melanoma as has been reported in cell lines, and warrant further search for another tumour suppressor on 9p21-22. This study also emphasizes the importance of examining uncultured primary tumours rather than cell lines to define early events in tumorigenesis.

The association of latent Epstein-Barr virus infection with hydroa vacciniforme

Patients with hydroa vacciniforme (HV)-like eruptions and malignant potential have been reported from Asia and Mexico, and those patients frequently had an associated latent Epstein-Barr virus (EBV) infection. In order to elucidate the association of latent EBV infection with HV, we studied six children with typical manifestations of HV by detection of EBV genes and EBV-related RNAs in biopsy specimens from cutaneous lesions. Cutaneous lesions of all six children with typical HV contained EBV-encoded small nuclear RNA (EBER)+ cells in 3-10% of the dermal infiltrates, whereas no Bam HI-H, l-fragment (BHLF) mRNA, or transcripts encoding EA-D antigen, were detected. No EBER + cells were detected in other inflammatory or benign lymphoproliferative skin disorders tested. Polymerase chain reaction amplification confirmed the presence of EBV DNA sequences in five of six biopsy specimens from the patients. Latent EBV infection is associated with the development of cutaneous lesions of HV.

Antiepiligrin (laminin 5) cicatricial pemphigoid associated with an underlying gastric carcinoma producing laminin 5

Although bullous pemphigoid and cicatricial pemphigoid are sometimes associated with malignancy, it remains uncertain whether such an association is pathogenetically related or just a coincidence attributable to the advanced age of the patients. We report a 61-year-old patient with antiepiligrin (laminin 5) cicatricial pemphigoid (AeCP) associated with an advanced gastric carcinoma. The gastric carcinoma cells in this patient were shown to produce laminin 5 by immunofluorescence microscopy, and the patient's serum contained autoantibodies directed against laminin 5 on immunoprecipitation. Furthermore, the blistering symptoms and the titre of antibasement membrane zone antibodies coordinately changed with the resection and subsequent relapse of the gastric cancer. These observations suggest that the gastric carcinoma producing laminin 5 may have induced the production of autoantibodies to this laminin, which were pathogenic to the skin and mucous membranes in this patient. This report demonstrates a link between this autoimmune subepithelial blistering disease and malignancy. It is of interest and potential great importance to examine other cases of AeCP for such a potential association.

Idiopathic benign biliary stricture

A rare case of idiopathic benign biliary stricture is reported. A 50-year-old man with liver dysfunction underwent ultrasonography, which revealed dilation of the intrahepatic bile ducts, and endoscopic retrograde cholangiopancreatography, which revealed a short, ring-like stenosis at the junction of the left and right hepatic ducts. Although a benign stricture was suspected, radiologic tests alone were insufficient to make a firm diagnosis. Therefore, a cholecystectomy and resection of the extrahepatic biliary tract were performed. Microscopic examination of the resected specimen demonstrated no evidence of malignancy. The final diagnosis was mild, localized, chronic cholangitis. The patient had not had previous biliary tract surgery, choledocholithiasis, nor did he have a congenital abnormality of the biliary tract, bile duct carcinoma, or pancreatic disease. Since there was no evidence of primary sclerosing cholangitis, the stricture was considered to be idiopathic.

Different effects of temocapril and cadralazine on electrocardiographic voltages and left ventricular mass in patients with essential hypertension

To assess whether electrocardiographic variables are useful to detect the regression of left ventricular (LV) mass after long-term antihypertensive treatment, we related electrocardiographic voltages to echocardiographic variables before and after treatment with an ACE inhibitor, temocapril (TEM), or direct vasodilator, cadralazine (CAD). Twenty-one patients with essential hypertension were treated with either TEM (n = 11) or CAD (n = 10) for one year. LV mass index (LVMI) by echocardiography and Sokolow-Lyon voltage (SV1 + RV5), Cornell voltage (RaVL + SV3) and RV5 + RV6 by standard 12-lead electrocardiographic voltages were determined before and after treatment. Both drugs decreased blood pressure to the same extent. Both Sokolow-Lyon voltage and RV5 + RV6 tended to decrease in the ACE group (40.0 +/- 9.4 to 37.2 +/- 9.4 mm and 44.7 +/- 13.5 to 41.7 +/- 11.7 mm, respectively, N.S.), but not in the CAD group (38.4 +/- 6.8 to 39.7 +/- 7.7 mm and 42.9 +/- 10.4 to 46.8 +/- 11.2 mm, respectively, N.S.). LVMI decreased in the ACE group (-24 +/- 22 g/m2), whereas it increased in the CAD group (37 +/- 27 g/m2, p < 0.01). Change in LVMI was correlated with the changes in RV5 + RV6 and Sokolow-Lyon voltage (r = 0.73, p < 0.01 and r = 0.70, p < 0.01, respectively), but not with that in Cornell voltage. These results indicated that the changes in voltage criteria of RV5 + RV6 and Sokolow-Lyon are useful to assess the change in LVM after antihypertensive treatment in patients with essential hypertension although voltage variables in electrocardiogram were not sensitive to detect changes in LVMI.

Relationship between electrocardiographic voltage and geometric patterns of left ventricular hypertrophy in patients with essential hypertension

To assess whether we could predict left ventricular (LV) geometric patterns on echocardiography from voltages in standard electrocardiograms (ECG) in patients with essential hypertension, standard 12-lead ECG and echocardiograms were recorded in 106 consecutive, untreated patients (50+/-11 yr old) with essential hypertension. Subjects were assigned to the following four groups based on relative wall thickness (RWT) and LV mass index (LVMI) as determined by echocardiography: a normal geometry group (n = 44), a concentric remodeling group (increased RWT and normal LVMI, n = 10), an eccentric hypertrophy group (increased LVMI and normal RWT, n = 23), and a concentric hypertrophy group (increased RWT and LVMI, n = 29). The following ECG variables were determined: Sokolow-Lyon voltage (SV1 = RV5: SL), Cornell voltage (RaVL + SV3: CN), sum of 12-lead QRS voltage (12-lead sum), and RV6/RV5 ratio (RV6/V5). LVMI correlated with SL, CN, and 12-lead sum, but not with RV6/V5 in the study group as a whole. The concentric hypertrophy group showed increased voltages for all ECG variables except RV6/V5. The concentric remodeling group showed increased voltages for SL and 12-lead sum, but a decreased RV6/V5 ratio. In contrast, the eccentric hypertrophy group had increased voltage only for the 12-lead sum. The combination of SL, RV6/V5, and CN showed modest sensitivity and specificity in the diagnosis of concentric remodeling, concentric hypertrophy, and normal geometry, but not in the diagnosis of eccentric hypertrophy. Conventional ECG criteria can predict LVMI, but not LV geometry in the patients with essential hypertension. The combination of SL, CN, and RV6/V5 is useful in differentiating the four LV geometric patterns seen in essential hypertension.

Comparison of genetic profiles between primary melanomas and their metastases reveals genetic alterations and clonal evolution during progression

To examine for the genetic basis of metastatic progression in cutaneous melanoma, we have compared loss of heterozygosity (LOH) of several selected chromosome regions that are implicated in the initiation and progression of melanoma, and alterations of the p16INK4a gene in 14 pairs of primary tumor and synchronous or asynchronous metastasis excised from the same patients. The most frequent genetic alteration during metastatic progression detected was the loss of p16INK4a protein expression (four of 14 cases), whereas no somatic p16INK4a gene mutations were found in any primary or metastatic tumors. LOH analyses showed that most of the chromosome losses including 6q, 8p, 9p, 9q, and 18q were shared between primary tumors and their metastases. Nevertheless, LOH of 6q and 11q and LOH of 7q not detected in primary tumors were, respectively, observed in two lymph node metastases. These results suggest that loss of p16INK4a protein expression (but not p16INK4a gene mutation) and the losses of chromosome arms 6q, 7q, and 11q play an important role in the acquisition of metastatic potential in sporadic melanoma. Furthermore, comparison of genetic profiles between the primary tumor and its metastasis revealed in several cases that heterogenous tumor cell populations might already exist at the early stage of tumorigenesis and evolve independently in the primary tumor and its metastasis, strongly suggesting that metastatic progression of sporadic melanoma is not accounted for by a linear progression model.

Homologous recombination, but not DNA repair, is reduced in vertebrate cells deficient in RAD52

Rad52 plays a pivotal role in double-strand break (DSB) repair and genetic recombination in Saccharomyces cerevisiae, where mutation of this gene leads to extreme X-ray sensitivity and defective recombination. Yeast Rad51 and Rad52 interact, as do their human homologues, which stimulates Rad51-mediated DNA strand exchange in vitro, suggesting that Rad51 and Rad52 act cooperatively. To define the role of Rad52 in vertebrates, we generated RAD52(-/-) mutants of the chicken B-cell line DT40. Surprisingly, RAD52(-/-) cells were not hypersensitive to DNA damages induced by gamma-irradiation, methyl methanesulfonate, or cis-platinum(II)diammine dichloride (cisplatin). Intrachromosomal recombination, measured by immunoglobulin gene conversion, and radiation-induced Rad51 nuclear focus formation, which is a putative intermediate step during recombinational repair, occurred as frequently in RAD52(-/-) cells as in wild-type cells. Targeted integration frequencies, however, were consistently reduced in RAD52(-/-) cells, showing a clear role for Rad52 in genetic recombination. These findings reveal striking differences between S. cerevisiae and vertebrates in the functions of RAD51 and RAD52.

Posttranscriptional control of adipocyte differentiation through activation of phosphoinositide 3-kinase

Differentiation of adipocytes is an important aspect of energy homeostasis. Although the transcriptional regulation of adipocyte differentiation is relatively well characterized, the subsequent molecular events remain unclear. The activity of phosphoinositide (PI) 3-kinase precipitated with antibodies to phosphotyrosine has now been shown to increase transiently during adipocyte differentiation of 3T3-F442A and of 3T3-L1 cells. PI 3-kinase activity precipitated with antibodies to insulin receptor substrate 1 (IRS1) and association of subunits of PI 3-kinase with IRS1 were also increased at this stage of differentiation, suggesting that IRS1 contributes to PI 3-kinase activation. Inhibition of the activation of PI 3-kinase by expression of dominant negative mutant subunits of the enzyme prevented adipogenesis, as assessed by lipid accumulation and expression of key adipocyte proteins such as GLUT4, adipsin, and aP2, suggesting that PI 3-kinase activation is essential for adipocyte differentiation. However, these mutant proteins did not affect either the expression of the transcription factor PPARgamma at the mRNA or protein level or the increase in the abundance of mRNAs encoding the adipocyte marker proteins. These results demonstrate that adipocyte differentiation is regulated at the posttranscriptional level and that activation of PI 3-kinase is required for this regulation.

Homologous recombination and non-homologous end-joining pathways of DNA double-strand break repair have overlapping roles in the maintenance of chromosomal integrity in vertebrate cells

Eukaryotic cells repair DNA double-strand breaks (DSBs) by at least two pathways, homologous recombination (HR) and non-homologous end-joining (NHEJ). Rad54 participates in the first recombinational repair pathway while Ku proteins are involved in NHEJ. To investigate the distinctive as well as redundant roles of these two repair pathways, we analyzed the mutants RAD54(-/-), KU70(-/-) and RAD54(-/-)/KU70(-/-), generated from the chicken B-cell line DT40. We found that the NHEJ pathway plays a dominant role in repairing gamma-radiation-induced DSBs during G1-early S phase while recombinational repair is preferentially used in late S-G2 phase. RAD54(-/-)/KU70(-/-) cells were profoundly more sensitive to gamma-rays than either single mutant, indicating that the two repair pathways are complementary. Spontaneous chromosomal aberrations and cell death were observed in both RAD54(-/-) and RAD54(-/-)/KU70(-/-) cells, with RAD54(-/-)/KU70(-/-) cells exhibiting significantly higher levels of chromosomal aberrations than RAD54(-/-) cells. These observations provide the first genetic evidence that both repair pathways play a role in maintaining chromosomal DNA during the cell cycle.

Polymerase chain reaction and immunohistochemistry frequently detect occult melanoma cells in regional lymph nodes of melanoma patients

AIMS

To evaluate immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR) for melanoma associated antigens (MAA) in detecting occult melanoma cells in lymph nodes which were missed on routine pathology.

METHODS

Occult melanoma cells were sought in 436 lymph nodes from 32 patients with cutaneous melanoma of the lower extremities by immunohistochemistry using the melanoma specific antibody HMB-45. The detection sensitivity of routine histology, immunohistochemistry, and RT-PCR was also compared in 23 lymph node samples from six patients.

RESULTS

Immunohistochemistry showed that 15 of 24 patients (62.5%) who had no detectable metastasis by routine histology had at least one lymph node containing HMB-45 positive cells, mostly seen singly in the medullary sinus. No difference was found in known clinicopathological prognostic factors and recurrence rates between the two groups of patients with and without occult HMB-45 positive cells. RT-PCR analyses showed that the nested PCR for tyrosinase was more sensitive than a combination of single round PCR for five different MAA, including tyrosinase, MART-1/Melan A, Pmel-17, TRP-1, and TRP-2, detecting tyrosinase mRNA in six nodes which were negative by HMB-45 immunohistochemistry.

CONCLUSIONS

Immunohistochemistry + RT-PCR is more sensitive than routine histology in detecting occult melanoma cells in lymph nodes. The nested PCR for tyrosinase should be used in future studies investigating the prognostic significance of such lymph node micrometastases.

Requirement for activation of the serine-threonine kinase Akt (protein kinase B) in insulin stimulation of protein synthesis but not of glucose transport

A wide variety of biological activities including the major metabolic actions of insulin is regulated by phosphatidylinositol (PI) 3-kinase. However, the downstream effectors of the various signaling pathways that emanate from PI 3-kinase remain unclear. Akt (protein kinase B), a serine-threonine kinase with a pleckstrin homology domain, is thought to be one such downstream effector. A mutant Akt (Akt-AA) in which the phosphorylation sites (Thr308 and Ser473) targeted by growth factors are replaced by alanine has now been shown to lack protein kinase activity and, when overexpressed in CHO cells or 3T3-L1 adipocytes with the use of an adenovirus vector, to inhibit insulin-induced activation of endogenous Akt. Akt-AA thus acts in a dominant negative manner in intact cells. Insulin-stimulated protein synthesis, which is sensitive to wortmannin, a pharmacological inhibitor of PI 3-kinase, was abolished by overexpression of Akt-AA without an effect on amino acid transport into the cells, suggesting that Akt is required for insulin-stimulated protein synthesis. Insulin activation of p70 S6 kinase was inhibited by approximately 75% in CHO cells and approximately 30% in 3T3-L1 adipocytes, whereas insulin-induced activation of endogenous Akt was inhibited by 80 to 95%, by expression of Akt-AA. Thus, Akt activity appears to be required, at least in part, for insulin stimulation of p70 S6 kinase. However, insulin-stimulated glucose uptake in both CHO cells and 3T3-L1 adipocytes was not affected by overexpression of Akt-AA, suggesting that Akt is not required for this effect of insulin. These data indicate that Akt acts as a downstream effector in some, but not all, of the signaling pathways downstream of PI 3-kinase.

Structural studies of endohedral metallofullerenes by synchrotron radiation powder diffraction

The endohedral natures of the metallofullerenes Y@C(82) and Sc(2)@C(8)4 are described based on synchrotron radiation powder diffraction experiments. For structural analysis, a combination of the maximum-entropy method (MEM) and Rietveld refinement was employed to analyse the complicated powder pattern. The obtained MEM charge densities show a clear distinction of the endohedral natures of the mono- and dimetallofullerenes.

Prognostic significance of allelic losses in primary melanoma

Loss of genetic material, including loss of loci on chromosome arms 6q, 9p, and 10q, occurs frequently in cutaneous melanoma but infrequently in benign melanocytic nevi or other melanocytic lesions, suggesting that these genetic alterations are important in the development and progression of melanoma. To examine whether allelic loss is of prognostic importance in melanoma, disease-free survival was related to loss of heterozygosity on 6q, 9p and 10q in 83 individuals with sporadic primary cutaneous melanoma. Loss of chromosome arms 6q and 10q were each significantly associated with a poorer clinical outcome (P=0.013 and P=0.001 respectively). In a subgroup of 41 subjects whose primary tumours were allelotyped, the fractional allelic loss (FAL) at 39 autosomal arms also significantly correlated with disease-free survival (P=0.013), with an increase in FAL associated with a poorer outcome; this association remained significant when controlled for tumour thickness (P=0.035). In addition, a greater proportion of cells were immunopositive for Ki67 antigen, p53 and p21WAF1 protein in the primary melanomas than in the benign melanocytic nevi, however, only p53 over-expression was significantly associated with improved survival (P=0.041).

Requirement of Src kinase Lyn for induction of DNA synthesis by granulocyte colony-stimulating factor

Treatment of cells with granulocyte colony-stimulating factor (G-CSF) leads to tyrosine phosphorylation of cellular proteins. G-CSF stimulates both the activation of protein tyrosine kinases Lyn, Jak1, and Jak2 and the association of these enzymes with the G-CSF receptor. Wild-type, lyn-deficient, and syk-deficient chicken B lymphocyte cell lines were transfected with the human G-CSF receptor, and stable transfectants were studied. G-CSF-dependent tyrosyl phosphorylation of Jak1 and Jak2 occurred in all three cell lines. Wild-type and syk-deficient transfectants responded to G-CSF in a dose-responsive fashion with increased thymidine incorporation, but none of the clones of lyn-deficient transfectants did. Ectopic expression of Lyn, but not that of c-Src, in the lyn-deficient cells restored their mitogenic responsiveness to G-CSF. Ectopic expression in wild-type cells of the kinase-inactive form of Lyn, but not of the kinase-inactive form of Jak2, inhibited thymidine incorporation in response to G-CSF. These studies show that the absence of Lyn results in the loss of mitogenic signaling in the G-CSF signaling pathway and that activation of Jak1 or Jak2 is not sufficient to cause mitogenesis.

Increased plasma granulocyte elastase levels in Behçet's disease

OBJECTIVE

To assess the role of granulocyte elastase in the development of thromboembolic vasculopathy in patients with Behçet's disease.

METHODS

Plasma granulocyte elastase-alpha1-proteinase inhibitor (E-PI) complex levels were measured by ELISA in 11 healthy subjects and 19 patients with Behçet's disease (BD). Eight of 19 patients showed deep vein thrombosis on (99m)technetium-macro-agglutinate albumin venography. Hemostatic variables were measured at the same time.

RESULTS

The mean plasma E-PI complex level was significantly higher in the 8 patients with than in the 11 patients without deep vein thrombosis (242 +/- 73 vs 165 +/- 97 ng/ml; p = 0.033). The mean plasma E-PI complex level in the 11 patients without deep vein thrombosis was significantly higher than in controls (165 +/- 97 vs 96 +/- 40 ng/ml; p = 0.038). Plasma E-PI complex levels correlated with the serum plasmin-alpha2-plasmin inhibitor complex levels (r = 0.621, p = 0.0084).

CONCLUSION

Plasma E-PI complex levels appear to be a useful marker of thromboembolic vasculopathy in BD.

A trichilemmal carcinoma arising from a proliferating trichilemmal cyst: the loss of the wild-type p53 is a critical event in malignant transformation

The genetic events responsible for tumor progression may be defined by careful analysis of genetic changes in well-chosen tumors which contain distinct cell populations representing each stage of progression. Here we report a case of a trichilemmal carcinoma arising in the wall of a proliferating trichilemmal cyst (PTC). DNA was isolated from microdissected areas of the PTC and the carcinoma respectively, and PCR-based microsatellite loss of heterozygosity (LOH) analysis as well as p53 gene sequencing performed. A CGA to TGA nonsense mutation at codon 306 in exon 8 of the p53 gene was found in both samples. LOH analysis showed that the PTC retained chromosome arm 17p (where the p53 gene resides), whereas the carcinoma was associated with the loss of this allele. All the other loci examined were retained including 3p, 9q, 13q and 17q in both tumor parts. The results confirm a common clonal origin of the PTC and the trichilemmal carcinoma, and strongly suggest that the complete loss of the wild-type p53 is a critical event responsible for malignant transformation in this particular case.

Rad51-deficient vertebrate cells accumulate chromosomal breaks prior to cell death

Yeast rad51 mutants are viable, but extremely sensitive to gamma-rays due to defective repair of double-strand breaks. In contrast, disruption of the murine RAD51 homologue is lethal, indicating an essential role of Rad51 in vertebrate cells. We generated clones of the chicken B lymphocyte line DT40 carrying a human RAD51 transgene under the control of a repressible promoter and subsequently disrupted the endogenous RAD51 loci. Upon inhibition of the RAD51 transgene, Rad51- cells accumulated in the G2/M phase of the cell cycle before dying. Chromosome analysis revealed that most metaphase-arrested Rad51- cells carried isochromatid-type breaks. In conclusion, Rad51 fulfils an essential role in the repair of spontaneously occurring chromosome breaks in proliferating cells of higher eukaryotes.

Molecular cloning of bovine thyrotropin-releasing hormone receptor gene

The genomic DNA encoding bovine Thyrotropin-Releasing Hormone Receptor (TRHR) was isolated from a bovine (Holstein) genomic library. Using PCR fragments of bovine candidate TRHR Transmembrane domain (TMD-III-IV) and C-terminus domain of mouse TRHR cDNA as probes, 9 x 10(5) plaques were screened to obtain several clones each containing the N-terminus or C-terminus domain. The bovine TRHR gene encoded 398 amino acids and has a long intron. The identity of the deduced amino acid sequence of bovine TRHR exceeded 88% that of mouse, rat or human. RT-PCR analysis indicated TRHR mRNA to be expressed in the pituitary and brain.

Implantation on the suture material and efficacy of povidone-iodine solution

Suture implantation of viable exfoliated tumour cells may be responsible for local recurrence of colorectal cancer. Using a colon cancer cell line, we obtained a suture implantation without intraperitoneal metastasis in about 80% of the control animals, when sacrificed on the 2nd postoperative week. The cytotoxic efficacy of povidone-iodine (PVP-I) was tested in vivo by a rat model with viable intracaecal tumour cells, and in vitro by trypan blue exclusion and the MTT assay. In vivo PVP-I at 5% significantly reduced the incidence of tumour growth, while the product at 2.5% had a significant effect in only the monofilament polypropylene group. In an in vitro toxicity study, PVP-I higher than 0.16% was effective at killing almost all tumour cells. PVP-I had effective cytotoxicity in vivo and in vitro, being less cytotoxic in vivo than in vitro.

Failure of germinal center formation and impairment of response to endotoxin in tumor necrosis factor alpha-deficient mice

To study the pathophysiologic roles of TNF alpha, we produced TNF alpha gene-disrupted mice by gene targeting. TNF alpha-deficient mice develop normally without any alteration in the lymphocyte populations. However, in these mice, the germinal center formation in the peripheral lymphoid organs failed in response to the T cell-dependent antigens. TNF alpha-deficient mice are resistant to lethal doses of endotoxin and D-galactosamine without hepatocyte apoptosis, yet demonstrate thymus apoptosis. Our results indicated an important role for TNF alpha in germinal center formation and in the sepsis-induced hepatocyte apoptosis that precedes liver failure.

Coupled vs. uncoupled pericardial constraint: effects on cardiac chamber interactions

The effects of pericardial constraint on cardiac chamber interactions were evaluated by mathematical model analyses based on a novel concept of coupled vs. uncoupled pericardial constraint. We hypothesized that the nature of pericardial constraint can be classified as a "coupled" constraint exerted by uniform liquid pressure or an "uncoupled" constraint exerted by regional surface pressure. The numerical solution of the model of atrioventricular interaction produced the characteristic waveforms in venous flows and right atrial/ventricular pressures in classical pericardial diseases. Coupled constraint accounted for the patterns in cardiac tamponade; uncoupled constraint accounted for those in constrictive pericarditis. Analytic solution of the model of ventricular interdependence demonstrated that coupled constraint (tamponade) produced greater gains in ventricular interdependence, increasing the occurrence of pulsus paradoxus, whereas uncoupled constraint (constriction) produced a greater effective right ventricular elastance, increasing the likelihood of Kussmaul's sign. Thus the concept of coupled vs. uncoupled constraint may offer a coherent framework to understand the characteristic steady-state and respiratory-induced hemodynamic events in multiple forms of pericardial diseases.

CedA is a novel Escherichia coli protein that activates the cell division inhibited by chromosomal DNA over-replication

We isolated and characterized a new gene related to the control of cell division regulation in Escherichia coli. At 30 degrees C, the dnaAcos mutant causes over-replication of the chromosome, and colony formation is inhibited. We found that, at this temperature, the dnaAcos cells form filaments; therefore, septum formation is inhibited. This inhibition was independent of SfiA, an inhibitor of the septum-forming protein, FtsZ. To identify factors involved in this pathway of inhibition, we isolated seven multicopy suppressors for the cold-sensitive phenotype of the dnaAcos mutant. One of these proved to be a previously unknown gene, which we named cedA. This gene encoded a 12 kDa protein and resided at 38.9min on the E. coli genome map. A multicopy supply of the cedA gene to the dnaAcos cells did not repress over-replication of the chromosome but did stimulate cell division of the host, the result being growth of cells with an abnormally elevated chromosomal copy number. Therefore, the expression level of the cedA gene seems to be important for inhibiting cell division of the dnaAcos mutant at 30 degrees C. We propose that over-replication of the chromosome activates a pathway for inhibiting cell division and that the cedA gene modulates this division control. In the dnaA+ background, cedA also seems to affect cell division.

The effects of long-term treatment on left ventricular hypertrophy in patients with essential hypertension: relation to changes in neurohumoral factors

This study compared the effects of 1 year of monotherapy with a calcium-channel antagonist (nilvadipine; NIL), an angiotensin-converting enzyme (ACE) inhibitor (temocapril; TEM), or a new vasodilator (cadralazine; CAD) on left ventricular (LV) hypertrophy in essential hypertension. Furthermore, to elucidate the mechanism responsible for regression of LV hypertrophy after treatment, LV mass index (LVMI) by echocardiography, plasma renin activity (PRA), aldosterone (PAC), norepinephrine, and atrial natriuretic peptide (ANP) concentration were measured before and after treatment. Thirty-six patients were randomly assigned to the NIL, TEM, or CAD groups. Blood pressure (BP) before treatment was 174 +/- 10/104 +/- 7, 173 +/- 18/103 +/- 8, and 171 +/- 16/103 +/- 7 mm Hg (mean +/- SD) in NIL, TEM, and CAD groups, respectively. BP was lower after treatment with each of the three test drugs than after the placebo period, and there were no differences in BP reduction among three groups. LVMI, in NIL and TEM, was reduced from 129 +/- 48 to 115 +/- 39 g/m2 and from 117 +/- 39 to 88 +/- 20 g/m2 (p < 0.05 and p < 0.01, respectively), whereas, in the CAD group, it was increased (110 +/- 30 to 138 +/- 27 g/m2; p < 0.01). In the CAD group, PAC decreased and ANP increased significantly. The change in LVMI correlated with that in BP for TEM and with that in ANP in all patients. These data indicated that LV volume overload as well as LV pressure overload may contribute to LV hypertrophy and that monotherapy with CAD is not desirable from the point of view of LV mass reduction in essential hypertension.

Expression of platelet-derived growth factor in lupus nephritis in MRL/MpJ-1pr/1pr mice

Platelet-derived growth factor (PDGF) plays an important role in the pathogenesis of mesangial proliferative glomerulonephritis. We examined PDGF expression and glomerular changes in lupus nephritis-prone MRL/MpJ-1pr/1pr (MRL/1) mice. The total number of nuclei per glomerular section and blood urea nitrogen (BUN) level were significantly increased in MRL/1 mice aged 20 weeks compared to those aged 8 weeks. A positive correlation existed between numbers of PDGF beta-chain-positive cells and glomerular cells in MRL/1 mice (r = 0.77, p < 0.01). The BUN level did not differ among MRL/MP-+2 (MRL/n) mice of different ages, but the glomerular cell number increased modestly with age. At the age of 20 weeks, the incidence of crescent formation per kidney tissue ranged from 9 to 32% (mean 19%) in MRL/1 mice but was 0 in MRL/n mice. PDGF beta-chain protein was expressed in the mesangium and crescents in 20-week-old MRL/1 mice but was expressed rarely in the glomeruli of MRL/n mice. These results suggest that the PDGF beta-chain plays an important role in glomerular cell proliferation and crescent formation in murine lupus nephritis.

Phosphoinositide 3-kinase is required for insulin-induced but not for growth hormone- or hyperosmolarity-induced glucose uptake in 3T3-L1 adipocytes

The(1) regulatory mechanism of glucose uptake in 3T3-L1 adipocytes was investigated with the use of recombinant adenovirus vectors encoding various dominant negative proteins. Infection with a virus encoding a mutant regulatory subunit of phosphoinositide (PI) 3-kinase that does not bind the 110-kDa catalytic subunit (delta p85) inhibited the insulin-induced increase in PI 3-kinase activity co-precipitated by antibodies to phosphotyrosine and glucose uptake in a virus dose-dependent manner. Overexpression of a dominant negative RAS mutant in which Asp57 is replaced with tyrosine (RAS57Y) or of a dominant negative SOS mutant that lacks guanine nucleotide exchange activity (delta SOS) abolished the insulin-induced increase in mitogen-activated protein kinase activity, but had no effect on PI 3-kinase activity or glucose uptake. Although GH and hyperosmolarity attributable to 300 mM sorbitol each promoted glucose uptake and translocation of glucose transporter (GLUT)4 to an extent comparable to that of insulin, these stimuli triggered little or no association of PI 3-kinase activity with tyrosine-phosphorylated proteins. Overexpression of delta p85 or treatment of cells with wortmannin, an inhibitor of PI 3-kinase activity, had no effect on glucose uptake or translocation of GLUT4 stimulated by GH or hyperosmolarity. Moreover, overexpression of delta SOS or RAC17N also did not affect the increase in glucose uptake induced by these stimuli. A serine/threonine kinase Akt, a constitutively active mutant of which was previously shown to stimulate glucose uptake, is activated by insulin, GH, and hyperosmolarity to approximately 4-fold, approximately 2.1-fold, and approximately 2.3-fold over basal level, respectively. These results suggest that insulin-induced but neither GH- or hyperosmolarity-induced glucose uptake is PI 3-kinase-dependent, and neither RAS nor RAC is required for glucose uptake induced by these stimuli in 3T3-L1 adipocytes.

Molecular cloning of bovine CD14 gene

Genomic DNA encoding bovine CD14 was isolated from a bovine (Holstein) genomic library. Utilizing PCR fragment of mouse CD14 gene as a probe, we screened 9 x 10(5) plaques and obtained 3 clones containing the bovine CD14 gene. DNA sequencing showed that bovine CD14 gene encodes 373 amino acids, and the coding sequence was separated by a 90 nt intron. The identity of the deduced amino acid sequence of bovine CD14 was 61-73% to those of mouse, rabbit and human. Northern blot analysis revealed that CD14 mRNA (1.5 kb) was expressed in the lung. Expression of CD14 mRNA was stimulated about 2-fold in bovine peripheral blood macrophage activated with LPS in vitro.

Intraalveolar expression of tumor necrosis factor-alpha gene during conventional and high-frequency ventilation

The effects of conventional mechanical ventilation (CMV) and high-frequency oscillatory ventilation (HFO) on intraalveolar expression of the tumor necrosis factor-alpha (TNF-alpha) gene were studied in surfactant-depleted rabbits. After lung lavage with saline, 13 rabbits were administered either CMV (n = 6) or HFO (n = 7) for 1 h at an FiO2 of 1.0 and a mean airway pressure of 13 cm H2O. Lung lavage was then repeated. The rabbits' RNA was extracted from the lavage cells, and mRNA for TNF-alpha was quantitated by reverse-transcription polymerase chain reaction using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an internal standard. At 1 h of ventilation, PaO2 was slightly lower with CMV than HFO, while lavage cell counts and cytology were similar between the two groups. The ratio of TNF-alpha mRNA to GAPDH mRNA increased with CMV (control, 0.48 +/- 0.04 [SE] versus 1 h, 1.02 +/- 0.14, p < 0.01) but did not change with HFO (0.55 +/- 0.07 versus 0.73 +/- 0.09). In a separate series of experiments, ten surfactant-depleted rabbits continued to be ventilated for 4 h either by CMV (n = 5) or HFO (n = 5). Conventional mechanical ventilation resulted in a progressive hypoxemia, decreased lung compliance, increased number of neutrophils in lung lavage fluid, and substantial morphological changes including hyaline membrane formation and neutrophil accumulation, whereas HFO was associated with minimal changes in such physiological and pathological abnormalities. These results suggest that activation of alveolar macrophages and production of proinflammatory cytokines may play a pivotal role in the early stage of ventilator-induced lung injury, and that ventilator mode (CMV or HFO) substantially modulates macrophage activation and hence the degree of lung injury.

A catalytic amino acid and primary structure of active site in Aspergillus niger alpha-glucosidase

The catalytic amino acid residue of Aspergillus niger alpha-glucosidase (ANGase) was identified by modification with conduritol B epoxide (CBE), a mechanism-based irreversible inactivator. The inactivation by CBE followed pseudo-first order kinetics. The interaction of CBE and ANGase conformed to a model with a reversible enzyme-inhibitor complex formed before covalent inactivation. A competitive inhibitor, Tris, decreased the inactivation rate. The incorporation of one mole of CBE per mole of ANGase was completely abolished the enzyme activity. A dissociated carboxyl group (-COO-) in the active site was suggested to attack the C-1 of CBE. ANGase was composed of two subunits (P1 and P2), of which P2 was modified by CBE. The labelled residue was included in a peptide (LY3) that was obtained from Lys-C protease digestion of CBE-bound P2. The sequence analysis of CBE-labelled LY3 showed that an Asp was the modified residue, that is, one of the catalytic amino acid residues of ANGase. The primary structure of LY3 was determined by analyzing the sequence of peptide fragments prepared by several proteases.

Genetic evidence for involvement of type 1, type 2 and type 3 inositol 1,4,5-trisphosphate receptors in signal transduction through the B-cell antigen receptor

Stimulation of B-cell antigen receptor (BCR) induces a rapid increase in cytoplasmic free calcium due to its release from intracellular stores and influx from the extracellular environment. Inositol 1,4,5-trisphosphate receptors (IP3Rs) are ligand-gated channels that release intracellular calcium stores in response to the second messenger, inositol 1,4,5-trisphosphate. Most hematopoietic cells, including B cells, express at least two of the three different types of IP3R. We demonstrate here that B cells in which a single type of IP3R has been deleted still mobilize calcium in response to BCR stimulation, whereas this calcium mobilization is abrogated in B cells lacking all three types of IP3R. Calcium mobilization by a transfected G protein-coupled receptor (muscarinic M1 receptor) was also abolished in only triple-deficient cells. Capacitative Ca2+ entry, stimulated by thapsigargin, remains unaffected by loss of all three types of IP3R. These data establish that IP3Rs are essential and functionally redundant mediators for both BCR- and muscarinic receptor-induced calcium mobilization, but not for thapsigargin-induced Ca2+ influx. We further show that the BCR-induced apoptosis is significantly inhibited by loss of all three types of IP3R, suggesting an important role for Ca2+ in the process of apoptosis.

Simultaneous measurement of serum 5-S-cysteinyldopa, circulating intercellular adhesion molecule-1 and soluble interleukin-2 receptor levels in Japanese patients with malignant melanoma

Serum 5-S-cysteinyl dopa (5-S-CD), circulating intercellular adhesion molecule-1 (cICAM-1) and soluble interleukin-2 receptor (sIL-2R) have each been reported as useful markers for melanoma progression. To assess the clinical relevance of these three markers, we simultaneously assayed their serum levels in 30 Japanese melanoma patients. Pre-surgical serum levels of 5-S-CD, cICAM-1 and sIL-2R were elevated in six, 13 and five patients respectively. These abnormal values returned to normal after curative surgery in most of the patients, suggesting a direct relationship to the presence of the primary tumour. Pre-surgical values of these three markers, either individually or in combination, did not predict the development of subsequent metastases. The sequential measurements of the three markers in eight patients who had relapse after surgery showed that serum 5-S-CD is the most useful marker for disease progression, although it is dependent on the melanin-producing ability of individual recurrent tumours. sIL-2R seemed to reflect in vivo activation of the host immune system and was a good indicator for predicting occult metastasis in selected cases. Circulating ICAM-1 levels were less relevant to the clinical disease course in our cases, although they tended to increase strikingly after liver metastasis. Our results in this limited number of cases show that the significance of the three markers varied with the individual and suggest that the simultaneous measurement of these markers may facilitate the early detection of metastases and proper therapeutic intervention.

p53 mutation spectrum in Japanese Bowen's disease suggests a role for mutagens other than ultraviolet light

The Japanese have a much lower incidence of nonmelanoma skin cancers (NMSCs) than Caucasians, presumably due in part to their skin type conferring relative protection from ultraviolet light radiation (UVR). To examine the contribution of environmental or endogenous mutagens other than UVR, which are expected to be relatively more important to the overall burden of NMSCs in the Japanese, we directly sequenced exons 5-8 of the p53 tumour suppressor gene in 29 Japanese patients with Bowen's disease, an in situ squamous-cell carcinoma of the skin. We found 9 mutations, including two CC:GG to TT:AA tandem transitions (presumably related to UVR), 3 transversions and 4 frameshift mutations. The mutational spectrum seen in our study contrasts with that we previously found in Bowen's disease from a Caucasian population, in keeping with a different aetiology for Bowen's disease in the respective populations. The unexpectedly high prevalence of frameshift mutations suggests that environmental mutagens other than UVR that preferentially induce deletion or insertion mutations may play an important role in the tumorigenesis of Japanese Bowen's disease, and warrants further investigation.

Evaluation of an extracorporeal membrane oxygenation system using a nonporous membrane oxygenator and a new method for heparin coating

A new heparin binding method was applied to a miniature extracorporeal membrane oxygenation (ECMO) system with a nonporous membrane oxygenator (the priming volume, 45 mL; the membrane surface area, 0.4 m2; maximal flow rate, 2 L/min) that is resistant to plasma leakage. The authors evaluated the stability of the immobilized heparin in vitro and the feasibility of this system in animals. Samples of hollow fibers and tubing were rinsed at 40 degrees C for 4 days in normal saline, Ringer's lactate, and 1 mol/L NaCl solution. Heparin activities on hollow fibers after rinsing were 99 +/- 2.3% (mean +/- SD), 96 +/- 3.9%, and 93 +/- 2.0% of the control in each solution, while those of the tubing were 87 +/- 4.1%, 86 +/- 3.1%, and 76 +/- 8.6%, respectively. Veno-arterial ECMO using this heparin-coated system was performed on five beagles (8 to 12 kg) for 10 hours. Neither major thrombus formation nor plasma leakage was detected during the procedure in spite of a low flow rate (300 mL/min) and a reduced activated clotting time (mean, 128 seconds). Platelets decreased to 52% of the control (P < .01) at 1 hour, but no progressive decrease was seen thereafter. Antithrombin-III decreased (P < .01) and thrombin/antithrombin III complex increased (P < .05 at 4 hours and P < .01 at 6, 8, and 10 hours) during bypass, but the changes of fibrinogen and fibrinopeptide A were not significant. Fibrinogen/fibrin degeneration products, fibrinopeptide B beta 15-42, and plasma-free hemoglobin levels did not rise significantly. O2 transfer of the oxygenators at a flow rate of 300 mL/min were 12.3 +/- 0.4 mL/min at 30 minutes, 14.3 +/- 1.2 mL/min at 5 hours, and 14.7 +/- 1.7 mL/min at 10 hours (no statistical difference). Histological examination of the brains and the kidneys showed no evidence of thromboembolic sequela in any of the animals. These results suggest that this new system is a promising device for long-term ECMO in which the amount of systemic heparinization can be reduced with the minimal possibility of plasma leakage.

Excitation of hypoglossal motoneurons responsible for tongue protrusions is associated with palatally induced jaw-closing reflex

The excitation of hypoglossal motoneurons innervating the genioglossus and geniohyoid muscles during transient jaw closing, the so-called jaw-closing reflex, was studied in cats. The application of diffuse pressure stimulation to the posterior palatal surface produced the jaw-closing reflex, and it was found that mechanosensory inputs from the posterior palatal mucosa sent excitatory synaptic inputs to both genioglossus and geniohyoid motoneurons. We demonstrated that, during the palatally induced jaw-closing reflex, the tongue extended at jaw closure and was still extended forward in the initial part of the opening phase. In five of 27 genioglossus motoneurons and nine of 23 geniohyoid motoneurons, the onset of burst was elicited before the onset of jaw closure. The remaining cells produced the onset of burst in the closing phase and in the initial part of the occlusal phase. However, the onset of excitatory postsynaptic potentials was 75-180 ms (n=20), earlier than that of jaw closure. During the jaw-closing reflex, the genioglossus and geniohyoid motoneurons were excited during the same phase of jaw movements and there was no difference in the onset of firing between the genioglossus and geniohyoid motoneurons. It is concluded that the excitation of the genioglossus and geniohyoid motoneurons may be associated with tongue protrusions during the palatally induced jaw-closing reflex.

[Repeated low-flow sevoflurane anesthesia: effects on hepatic and renal function in beagles]

We studied the effects of repeated low-flow sevoflurane anesthesia for 6 hours. Five beagle dogs received 1.3 MAC (3%) sevoflurane anesthesia. Anesthesia of 6 hours was repeated on at the 7th day after the first anesthesia. Compound A gas samples were collected from the inspiratory limb during anesthesia. Concentrations of serum and renal fluoride, hepatic and renal function parameters were measured during and up to 7 days after the first and second anesthesia. The peak concentration of compound A was 23.7 +/- 3.6 ppm at 2 hours and the same level remained during the anesthesia. Plasma fluoride level exceeded 50 mmol.l-1 during anesthesia and rapidly decreased to the preanesthesia level thereafter. Serum GOT increased slightly only on the first postanesthesia day. No significant changes in other blood chemistry studies were observed. The excretion of renal tubular enzymes did not increase during and after anesthesia. Repeated low flow sevoflurane anesthesia in beagles did not affect hepatic and renal function significantly.

Tape stripping induces marked epidermal proliferation and altered TGF-alpha expression in non-lesional psoriatic skin

Psoriasis is a chronic inflammatory disorder characterized by epidermal hyperproliferation. Although recent evidence suggests that T cell activation is a primary trigger for psoriasis lesions, there may be alterations in the keratinocyte growth regulatory pathways which induce epidermal hyperproliferation in psoriatic patients. To test this hypothesis, we investigated the proliferative activity of epidermal keratinocytes 48 h after tape stripping, one of the standard mechanical ways to stimulate the epidermis, in 20 psoriasis patients and in 18 controls. Epidermal cell kinetics were assessed with DNA flow cytometry, the mitotic index, bromodeoxyuridine incorporation, Ki-67 antigen expression and DNA polymerase alpha expression. The expression of TGF-alpha and EGF receptors, critical mediators of keratinocyte proliferation, were also investigated immunohistochemically. The results of multiparameter assays showed that the baseline proliferative activity in uninvolved skin was the same in psoriasis patients and normal controls. After tape stripping, although both psoriasis patients and the normal controls showed significant increases in epidermal cell proliferation, the values of all the parameters investigated were significantly greater in the psoriasis patients than in the normal controls. EGF receptors were overexpressed in basal and suprabasal keratinocytes after tape stripping in both the psoriasis patients and the normal controls. In contrast, overexpression of TGF-alpha was only observed in the patients with psoriasis, which may explain their increased proliferative response to trauma.

Low frequency of allelic loss in skin tumours from immunosuppressed individuals

Organ transplant recipients receiving immunosuppression show a dramatically increased risk of non-melanoma skin cancer. The cause of this increase is not known. We report that the rate of loss of heterozygosity (at all the loci we examined) was significantly lower in tumours from immunosuppressed individuals than in tumours from immunocompetent subjects [20 out of 148 (14%) vs 157 out of 428 (37%); P< 0.0001]. These results suggest that tumours in immunosuppressed individuals have a different molecular pathogenesis.

Tumour cells of extramammary Paget's disease do not show either p53 mutation or allelic loss at several selected loci implicated in other cancers

Extramammary Paget's disease is a particular form of skin cancer of unknown histogenesis. To look for the genetic defects underlying the pathogenesis of this tumour, we have examined loss of heterozygosity (LOH), p53 and human papillomavirus (HPV) status, and the expression of c-erbB-2 and bcl-2 proteins in 14 cases. Unexpectedly, no LOH was detected at several loci commonly lost in other human cancers (namely 3p, 9p, 9q, 13q, 16q, 17p, and 17q) in 12 tumours examined. Altered p53 protein expression was entirely or mostly negative in all 14 cases. Direct sequencing of exons 5-8 of the p53 gene in eight cases revealed no mutation. Polymerase chain reaction amplification of the L1 gene of human papillomavirus (HPV) did not detect the virus that could inactivate p53 and retinoblastoma tumour-suppressor gene products. As expected, c-erbB-2 proto-oncogene protein was overexpressed in six cases. The expression of bcl-2 was negative in all cases. The results presented in this study suggest that molecular events underlying extramammary Paget's disease differ from those of other common epithelial malignancies and that tumour-suppressor genes located in chromosome regions not examined in this study may be important.