Reactivity of mammalian 15-lipoxygenase with phospholipids in large unilamellar liposomes

The reactivity of rabbit reticulocyte 15-lipoxygenase (15-LOX) with phosphatidylcholine (PC) possessing linoleic acid (LA-PC), arachidonic acid (AA-PC), or docosahexaenoic acid (DHA-PC) was investigated by measuring oxygen uptake in the suspension of large unilamellar liposomes (LUV). The 15-LOX reaction with PC LUV was found to follow Michaelis-Menten kinetics. The apparent values of the Michaelis constants (K(m)) of LUV of LA-PC, AA-PC, and DHA-PC were nearly the same (1.0-1.2 mM). However, the maximum velocity (Vmax) of DHA-PC was obviously two to three times lower than those of LA-PC and AA-PC. On the other hand, the oxidizability of PC per bis-allylic H of unsaturated fatty acids in the free radical chain reaction of LUV decreased with increasing degree of unsaturation, that is, LA-PC > AA-PC > DHA-PC. These results suggested that the oxidizability of the DHA moiety incorporated into biomembranes is not necessarily high in lipoxygenase reaction as in free radical chain reaction.

Mechanisms of tumor-induced immunosuppression: evidence for contact-dependent T cell suppression by monocytes

BACKGROUND

The progressive growth of tumors in mice is accompanied by down-regulation of specific T cell responses. The factors involved in this suppression are not completely understood. Here, we have developed a model to examine the role of host immune effector cells in the inhibition of T cell function. In this model, progressive growth of a colon carcinoma line, CT26, is accompanied by loss of T cell response to alloantigens in both cytolytic and proliferation assays.

MATERIALS AND METHODS

The CT26 tumor was inoculated into BALB/c syngeneic mice. Tumor growth, cytolytic T cell responses, lymphocyte proliferation, and flow cytometric analysis was performed in tumor-bearing animals 7 or 28 days after tumor inoculation.

RESULTS

Spleen cells from tumor-bearing mice were found to suppress the proliferative response of spleen cells from normal mice to alloantigens. Examination of the spleen cell population by FACS analysis revealed an increase in the percentage of monocytes as defined by expression of CD11b, the Mac-1 antigen. Removal of the Mac-1-positive cells from the tumor-bearing hosts spleen relieved suppression of the tumor-bearing mouse spleen cell proliferative response to alloantigens, and addition of the Mac-1-positive enriched cells suppressed proliferation of normal T cells in response to alloantigens. Cell contact was required for this inhibition.

CONCLUSIONS

Tumor induction of suppressive monocytes plays an important role in the general immunosuppression noted in animals bearing CT26 tumors. Identification of the mechanisms responsible for this effect and reversal of tumor-induced macrophage suppression may facilitate efforts to develop effective immunotherapy for malignancy.

Quantitative study of Helicobacter pylori in gastric mucus by competitive PCR using synthetic DNA fragments

Helicobacter pylori is closely related to upper gastrointestinal diseases, and the precise evaluation of H. pylori infection is necessary for the treatment of these diseases. The aim of the present study was to establish a method for the quantitative detection of H. pylori. We applied a competitive PCR method using various amounts of synthetic DNA fragments containing the same primer-binding and a subset of the same template sequences as the target competing for primer binding and amplification in order to quantify H. pylori in gastric mucus. The results obtained by this method were compared with the results of histological examination, the rapid urease test, bacterial culture, the [13C]urea breath test, and urea and ammonia measurements in gastric juice. As the quantity of H. pylori in gastric mucus increased, the rates of positivity of histological examination, the rapid urease test, and bacterial culture increased. The quantity of H. pylori in gastric mucus was also significantly correlated with the results of the [13C]urea breath test and was negatively correlated with the urea/ammonia ratio in gastric juice. The competitive PCR method provides an objective measure of the quantity of H. pylori and makes it possible to distinguish true negatives from false negatives due to incomplete PCR and true positives from false positives due to contamination. This method is very useful for the precise evaluation of gastric H. pylori infection.

Expression of the RET proto-oncogene in normal human tissues, pheochromocytomas, and other tumors of neural crest origin

In order to evaluate the roles of the RET proto-oncogene in normal human tissues and tumors derived from the neural crest cells, we examined the expression of RET in a variety of adult human tissues, pheochromocytomas, medullary thyroid carcinomas (MTCs), ganglioneuromas, and a neurinoma. Northern blot analysis demonstrated that RET is normally expressed in the adrenal medulla and cerebellum among adult human tissues. RET transcripts were detected in all of 11 sporadic and one familial pheochromocytomas. The levels of RET mRNA were higher in 8 of 12 pheochromocytomas than in the normal adrenal medulla, indicating that RET is overexpressed in the majority of sporadic pheochromocytomas. There was a considerable difference in the level of RET expression in each pheochromocytoma ranging from 0.2 to 10 times the transcripts found in the normal adrenal medulla. The sizes of the transcripts of 7.0, 6.0, 4.5, and 3.9 kb were the same as those found in the adrenal medulla, suggesting no rearrangements of the RET gene in pheochromocytomas. Southern blot analysis revealed neither amplification nor gross structural changes in the RET gene. RET was also expressed at high levels in four MTCs examined, whereas its transcripts were detected at low abundance in only one of three ganglioneuromas. RET was not expressed in a neurinoma. These results suggest that RET may play some roles in a limited range of adult human tissues, and that its high levels of expression may have relevance to development or growth of pheochromocytomas and MTCs.

[Mitral reconstruction in patients with infective endocarditis]

Between June 1992 and October 1993, 5 patients with infective endocarditis in native mitral valve underwent open heart surgery. The patients ranged in age from 51 to 64 years and were all males. According to NYHA functional classification, 4 patients were class II and one was class III. Surgery was indicated because of hemodynamic deterioration (2 pts), echocardiographic mobile vegetation with or without previous emboli (2 pts) and both condition (1 pt). Before surgery the patients were afebrile and had negative serum CRP and negative blood cultures for at least one week after adequate medical treatment. The leaflet lesions found in the 5 patients were vegetation (2 pts), perforation (1 pt), calcification (1 pt) and thickening (2 pts). The chordal lesions found were rupture (5 pts) and thickening (1 pt). The infective lesions did not extend to the annulus. The mitral leaflets, including all apparently infectious lesions, were resected in a V-shaped fashion and then valve reconstruction was performed. The resected parts were sutured together with anchoring chordae. The annuloplasty with Teflon-tapes was also added. Postoperatively, all 5 patients showed a dramatic improvement in hemodynamics and endocarditis did not recur during 22 to 38 months of follow-up. The patients who received the repair did not require Warfarin. This study shows that mitral valve repair is an acceptable operation in patients with infective endocarditis, giving the patients better quality of life than mitral valve replacement when (1) infectious lesion are limited to mitral leaflet and chordae, (2) there is no severe calcification of the mitral valve, (3) the infection is healed by the adequate antibiotic therapy.

Structural studies of mitomycins. VIII. Mitomycin D hydrate, C15H18N4O5.1.5H2O

The title compound, [1aS]-6-amino-1, 1a,2,4,7,8,8a,8b-octahydro-8a-hydroxy-1,5-dimethyl-4,7-dioxoazirino++ +[2',-3': 3,4]pyrrolo[1,2-a]indol-7-ylmethyl, is a mitomycin derivative, mitomycins being antitumor antibiotics. The O atoms of the quinone ring deviate significantly from the least-squares plane through the quinone ring.

Differential regulation of G-protein-mediated signaling by chemokine receptors

Monocyte chemoattractant protein-1 (MCP-1) is a member of a family of chemotactic cytokines that induce directed migration of leukocytes via activation of seven-transmembrane domain receptors. To identify G-proteins that couple to the two forms of the MCP-1 receptor, as well as to related chemokine receptors, we have performed cotransfection experiments in mammalian cells. In COS-7 cells, the type A and type B MCP-1 receptors coupled to Galphai, Galphaq, and Galpha16, whereas the macrophage inflammatory protein-1alpha/RANTES (regulated on activation, normal T cell-expressed and secreted) receptor (C-CR1) coupled to Galphai and Galphaq but failed to couple to Galpha16. In HEK-293 cells, however, the MCP-1 receptors and C-CR1 coupled to Galphaq but failed to couple to Galpha16. In contrast, the interleukin-8 and C5a receptors did not couple to Galphaq in either COS-7 or HEK-293 cells but did couple to Galpha16. Exchange of intracellular loops between the MCP-1 and interleukin-8 receptors to create chimeric receptors revealed that the third loop of the MCP-1 receptor accounted for virtually all of the coupling to Galphaq. We conclude that the MCP-1 and related chemokine receptors couple to multiple G-proteins, that coupling is cell type-specific, and that the third intracellular loop of the C-C type receptors mediates Galphaq coupling.

Lead nitrate inhibits the induction of CYP1A mRNAs by aromatic amines but not by aryl hydrocarbons in the rat liver

The effects of lead nitrate on the induction of hepatic cytochrome P450IA (CYP1A) isoforms, mainly CYP1A2, by aromatic amines (2-methoxy-4-aminoazobenzene, 2-amino-3-methyl-9H-pyrido [2,3-b]indole and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) and aryl hydrocarbons (3-methylcholanthrene, benzo[a]pyrene and beta-naphthoflavone) in male F344 rats were examined at the levels of mRNA, protein and activity of the enzymes. Pretreatment of rats with lead nitrate suppressed the expression of hepatic CYP1A enzyme(s), especially CYP1A2, at both levels of protein and activity of the enzyme(s) by treatment with an aromatic amine or an aryl hydrocarbon. On the other hand, the lead nitrate pretreatment suppressed the induction of CYP1A mRNA(s) by an aromatic amine but not by an aryl hydrocarbon. These findings indicate that lead nitrate suppresses the expression of CYP1A enzymes at both stages of post-translation of mRNAs and transcriptional activation of the genes, and further suggest that the pathway for the transcriptional activation of the CYP1A genes by the aromatic amines is different from that by the aryl hydrocarbons.

PAF and PAF acetylhydrolase in the nervous system

PAF acetylhydrolase is a key enzyme of PAF inactivation. Intracellular PAF acetylhydrolase isoform Ib is a heterotrimeric enzyme composed of alpha-, beta- and gamma-subunits. The beta- and gamma-subunits act as a catalytic unit and their amino acid sequences are homologous. The alpha-subunit is not essential for catalytic activity but is a product of the causative gene for Miller-Dicker lissencephaly, suggesting this subunit plays an important role in brain development.

Optimal control algorithm for pneumatic ventricular assist devices: its application to automatic control and monitoring of ventricular assist devices

We developed a control and monitoring unit for pneumatic ventricular assist devices (VADs), which provides optimal fill and empty control and real-time evaluation of pump performance. The flow signal of the inflow cannula is integrated every beat to yield pump filling volume per pump diastole. The ejection signal is triggered when pump filling reaches a preset level. The instantaneous mean flow of each beat (stroke volume/cycle length) is compared with the previous beat, and the threshold level is readjusted to optimize flow. This feedback loop is repeated every beat, and pump filling is immediately adjusted to yield maximum pump flow. Simultaneously the mean flow of every 10 beats is compared with that of the previous 10 beats; then, the ejection time is readjusted to optimize flow. Initial clinical application of this unit supports its effectiveness and reliability.

[Outcome of initial treatment with high-dose vitamin B6, valproate sodium or clonazepam in West syndrome]

We reviewed the outcome (seizures and development) of 25 cases with West syndrome in which antiepileptic drugs (valproate sodium, clonazepam) or high doses of vitamin B6, instead of ACTH therapy, were administered for the initial treatment. Five of 9 cryptogenic cases (56%) and 4 of 16 symptomatic cases (25%) showed complete cessation of spasms. In cryptogenic cases, response to vitamin B6, valproate sodium or clonazepam was not predicted by clinical features (age of onset, seizure type, initial EEG finding or treatment lag). On the other hand, response to these drugs was correlated with some clinical findings in symptomatic cases; all infants with neurocutaneous syndrome (tuberous sclerosis, neurofibromatosis type 1) had controlled infantile spasms, while none of patients with severe neonatal asphyxia or with prior other seizures responded. Twenty of 25 patients have been followed-up. The average age at follow-up was 5 years and 8 months. Prognosis of both cryptogenic and symptomatic "responders" was favorable; all had seizures controlled, and 50% had normal psychomotor development or only mild impairment (DQ > 70). Symptomatic "nonresponders" had the worst prognosis. Our results suggest that choice of drug in the initial treatment of West syndrome should be determined by clinical features (especially etiology).

[Prognosis of hepatic metastasis from colorectal cancer following arterial infusion chemotherapy--assessment from the percentage of tumor involved area and tumor markers]

Prognosis of hepatic metastasis from colorectal cancer following arterial infusion chemotherapy was studied from the percentage of tumor involved area (PTIA) and tumor markers. The PTIA was calculated by the following formula: sigma S'/ sigma S, with S' as the tumor area and S as the liver area on each CT slice. The PTIA was 0.76 to 31.1%, and the average was 6.84%. As for the correlation between the PTIA and the prognosis, a statistically significant reverse correlation was found in the cases of death (r = -0.455, p < 0.05, n = 22). In the tumor regression effect of NC cases, the 50% survival time was 24.4 months in cases showing a decrease in CEA or CA19-9 and 18.7 months in the cases showing an increase. Prognosis of the former cases was significantly better than that of the latter cases (p < 0.05). Therefore, PTIA and the decrease in CEA or CA19-9 in the cases of hepatic arterial infusion chemotherapy for metastasis from colorectal cancer seemed important factors reflecting prognosis.

[Tau protein in cerebrospinal fluid--a potential marker of Alzheimer's disease]

Levels of the microtubule-associated protein tau in cerebrospinal fluid (CSF-tau) were measured in samples from 87 patients with Alzheimer's disease (AD), 114 patients with non-AD neurological diseases, and 22 normal control subjects, by sandwich enzyme-linked immunosorbent assay. The CSF-tau level was significantly higher in patients with AD than in patients with non-AD neurological diseases and in controls. High CSF-tau levels were found irrespective of age at onset, apolipoprotein E genotype, clinical stage, and ethnic group. Western blots of AD CSF proteins revealed two to three immunoreactive bands with apparent molecular mass between 50 and 65 kDa, which is consistent with phosphorylated CSF-tau. These results suggest that CSF-tau reflects progressive accumulation of tau due to the progressive death of neurons in the AD brain. Assay of CSF-tau may prove to be a reliable diagnostic test for AD.

Angiotensin II type 1 receptor signals through Raf-1 by a protein kinase C-dependent, Ras-independent mechanism

To understand the molecular mechanism by which the angiotensin II (AII) type 1 receptor (AT1 receptor) transduces its biological signal, we examined the role of various signaling molecules involved in AT1 receptor signaling in Chinese hamster ovary cells stably transfected with the AT1 receptor. AT1 receptor-transfected cells responded to AII treatment by inhibiting adenylyl cyclase, increasing the intracellular Ca2+ concentration, and activating protein kinase C (PKC) alpha and PKC epsilon. AII also activated the c-fos gene and mitogen-activated protein (MAP) kinases. The activation of PKC, the c-fos gene, and MAP kinases was blocked by inhibition of PKC induced by pretreatment with 12-O-tetradecanoylphorbol-13-acetate but not by pretreatment with pertussis toxin, suggesting that PKC couples to the activation of the the c-fos gene and MAP kinases. In addition, AII activated Raf-1 and MAP kinase kinase in a PKC-dependent manner. A dominant negative mutant of Ras had no effect on AII-induced MAP kinase or c-fos gene activation. Thus, the AT1 receptor signals through Raf-1 and its downstream signaling molecules by a PKC-dependent mechanism that does not involve Ras activation.

Serum amyloid P component level in Alzheimer's disease

Serum amyloid P component (AP) is a normal plasma constituent that is observed in senile plaques and neurofibrillary tangles in brains of Alzheimer's disease (AD) patients. In this study we have evaluated the AP levels in sera of 16 patients with AD and in 16 control subjects by enzyme-linked immunosorbent assay. The AP level was 22.4 +/- (SD) 7.0 micrograms/ml in the AD group and 34.4 +/- (SD) 6.6 micrograms/ml in the control group. The AP level in the AD group was significantly lower than that of the control group (p < 0.01). In the control group, there was no correlation between AP levels and age. Our results suggest that the production of AP by the liver (hepatocytes), thought to be the only source, may be suppressed in AD patients and that the deposition of AP in senile plaques and neurofibrillary tangles is not due to its overproduction.

Expression of apolipoprotein E in normal and diverse neurodegenerative disease brain

Brains from 21 patients with Alzheimer's disease (AD), nine with diffuse Lewy body disease (DLBD), six with progressive supranuclear palsy (PSP) and five with Parkinson's disease (PD) as well as 20 normal subjects were examined to detect apolipoprotein E (ApoE) by immunohistochemistry and immunoblotting. ApoE antigenicity was optimally preserved in Bouin-fixed tissues compared with those fixed in neutral-buffered formalin, 70% ethanol or denatured by microwave energy. ApoE immunoreactivity was prominent in senile plaques and in intra- and extra-neuronal tangles, as well as in a diverse neurones and their processes and astroglial cells. Notably, tangles in PSP and Lewy bodies in PD and DLBD were both devoid of ApoE immunoreactivity. Western blots of cerebral cortex revealed an immunoreactive ApoE band with mol. wt of 34 kDa. Our results suggest that ApoE is not a crucial factor in the development of neuronal inclusions in DLBD, PSP and PD.

Structural studies of mitomycins. VII. Mitomycin G

The title compound, [1aS-(1a alpha, 8a alpha, 8b alpha)]-6-amino-1, 1a,2,8,8a,8b-hexahydro-8a-methoxy-1,5-dimethyl-8-methyleneazirino [2',3':3,4]pyrrolo[1,2-a]indole-4,7-dione, C15H17N3O3, is a derivative of the mitomycins, which are antitumor antibiotics. The quinone O atoms deviate significantly from the least-squares plane of the quinone ring.

The RET proto-oncogene in sporadic pheochromocytomas

In order to evaluate the role of RET proto-oncogene in the development and growth of pheochromocytomas, we examined mutations in RET and expression of RET in 7 cases of sporadic pheochromocytomas. Tumors were screened for mutations in exons 10 and 11 and codon 918 which are identified in multiple endocrine neoplasia types 2A and 2B. No mutations were found in these regions in all of the sporadic pheochromocytomas examined. On the other hand, RET mRNA was detected in all pheochromocytomas and the levels of RET expression were higher in 5 of 7 pheochromocytomas than in normal adrenal medulla, indicating that RET is overexpressed in a sizable portion of sporadic pheochromocytomas. These results suggest that high levels of expression of RET may have relevance to the development or growth of sporadic pheochromocytomas.

Biological markers for the clinical diagnosis of Alzheimer's disease

There is a compelling need to develop biological marker(s) to confirm a clinical diagnosis of Alzheimer's disease (AD) during life in order to unequivocally identify AD patients for emerging therapeutic interventions. This review describes recent advances in the development of diagnostic marker(s) for AD. They include polymorphism of apolipoprotein E (ApoE) and alpha 1-antichymotrypsin as well as cerebrospinal fluid (CSF) tau and CSF-amyloid beta-protein levels, skin biopsy, and pupil dilatation assay by anti-cholinergic agent. In conclusion, ApoE genotyping should not be used as a sole diagnostic test for AD, and that monitoring of CSF-tau appeared to be most promising and reliable diagnostic aid.