Molecular cloning and physical mapping of the otsBA genes, which encode the osmoregulatory trehalose pathway of Escherichia coli: evidence that transcription is activated by katF (AppR). It has been shown previously that the otsA and otsB mutations block osmoregulatory trehalose synthesis in Escherichia coli. We report that the transcription of these osmoregulated ots genes is dependent on KatF (AppR), a putative sigma factor for certain stationary phase- and starvation-induced genes. The transcription of the osmoregulated bet and proU genes was not katF dependent. Our genetic analysis showed that katF carries an amber mutation in E. coli K-12 and many of its derivatives but that katF has reverted to an active form in the much-used strain MC4100. This amber mutation in katF leads to strain variations in trehalose synthesis and other katF-dependent functions of E. coli. We have performed a molecular cloning of the otsBA genes, and we present evidence that they constitute an operon encoding trehalose-6-phosphate phosphatase and trehalose-6-phosphate synthase. A cloning and restriction site analysis, performed by comparing the cloned fragments with the known physical map of the E. coli chromosome, revealed that the otsBA genes are situated on a 2.9-kb HindIII fragment located 8 to 11 kb clockwise of tar (41.6 min).


Molecular characterization of the 28- and 31-kilodalton subunits of the Legionella pneumophila major outer membrane protein. The major outer membrane protein of Legionella pneumophila exhibits an apparent molecular mass of 100 kDa. Previous studies revealed the oligomer to be composed of 28- and 31-kDa subunits; the latter subunit is covalently bound to peptidoglycan. These proteins exhibit cross-reactivity with polyclonal anti-31-kDa protein serum. In this study, we present evidence to confirm that the 31-kDa subunit is a 28-kDa subunit containing a bound fragment of peptidoglycan. Peptide maps of purified proteins were generated following cyanogen bromide cleavage or proteolysis with staphylococcal V8 protease. A comparison of the banding patterns resulting from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed a common pattern. Selected peptide fragments were sequenced on a gas phase microsequencer, and the sequence was compared with the sequence obtained for the 28-kDa protein. While the amino terminus of the 31-kDa protein was blocked, peptide fragments generated by cyanogen bromide treatment exhibited a sequence identical to that of the amino terminus of the 28-kDa protein, but beginning at amino acid four (glycine), which is preceded by methionine at the third position. This sequence, (Gly-Thr-Met)-Gly-Pro-Val-Trp-Thr-Pro-Gly-Asn ... , confirms that these proteins have a common amino terminus. An oligonucleotide synthesized from the codons of the common N-terminal amino acid sequence was used to establish by Southern and Northern (RNA) blot analyses that a single gene coded for both proteins. With regard to the putative porin structure, we have identified two major bands at 70 kDa and at approximately 120 kDa by nonreducing SDS-PAGE. The former may represent the typical trimeric motif, while the latter may represent either a double trimer or an aggregate. Analysis of these two forms by two-dimensional SDS-PAGE (first dimensions, nonreducing; second dimensions, reducing) established that both were composed of 31- and 28-kDa subunits cross-linked via interchain disulfide bonds. These studies confirm that the novel L. pneumophila major outer protein is covalently bound to peptidoglycan via a modified 28-kDa subunit (31-kDa anchor protein) and cross-linked to other 28-kDa subunits via interchain disulfide bonds.


The effect of 3 mouthrinses on plaque and gingivitis development. The aim of this study was to evaluate the effect of 3 mouthrinses, Listerine Antiseptic (thymol), Peridex (chlorhexidine), Perimed (povidone iodine and hydrogen peroxide), and a placebo (water) on the development of dental plaque and gingivitis, when used as the only oral hygiene procedure for 14 days. 71 subjects were entered into a randomized, double-blind study. At the baseline examination, papillary bleeding score (PBS), and plaque index (PI) were registered, after which subjects received supragingival prophylaxis and were assigned to 1 of 4 study cells. Subjects were asked to refrain from all oral hygiene procedures except for the supervised 14-day 2 x daily rinsing with the assigned preparation. At day 14, the same clinical parameters were again registered. Statistical analysis was performed by a one-way analysis of variance (ANOVA) to compare the 4 groups, followed by Duncan's multiple range test to determine specific group differences. At baseline, average PBS and PI scores were similar for all 4 groups. After 14 days, the average PBS for Peridex and Perimed was significantly lower than for Listerine Antiseptic and water. The frequency of interdental units with a PBS greater than 2 was significantly lower for Peridex and Perimed than for Listerine Antiseptic and water. We concluded that both Peridex and Perimed were effective in reducing plaque and gingivitis when used as a 2 x daily mouthrinse by subjects refraining from other oral hygiene procedures. In vitro, a synergistic effect was assumed when inhibition was achieved with Perimed at the same or greater dilution than was achieved with povidone-iodine alone.


Cutaneous angiocentric T-cell lymphoma associated with Epstein-Barr virus. Two unusual cases of cutaneous angiocentric T-cell lymphoma were found to be associated with Epstein-Barr virus infection. The objective was to study the clinical course and the response of the disease to conventional chemotherapy. Histologic specimens from both patients were studied. Clonal proliferation was assessed by Southern blot hybridization. The disease in both patients was rapidly progressive and responded poorly to aggressive treatment. Biopsy specimens showed infiltration of atypical lymphoid cells with angiocentricity and angiodestruction, which probably resulted in the observed tissue necrosis. Clonal proliferation of Epstein-Barr virus DNA was detected in tissue from primary skin lesions and disseminated nasal lesions. Epstein-Barr virus-associated angiocentric T-cell lymphoma in our patients was characterized by an aggressive course and resistance to conventional chemotherapy. A search for Epstein-Barr virus and the human T-lymphotropic virus should be performed in patients with atypical features of cutaneous T-cell lymphoma.


Autoantibodies to leucocyte antigens in hydralazine-associated nephritis. Clinical and laboratory findings and drug history were studied in 17 patients with suspected hydralazine-associated nephritis, five of whom only had renal disease, while twelve also had extrarenal manifestations. Renal biopsies revealed extracapillary proliferative or focal segmental proliferative glomerulonephritis in 10 patients, and tubulo-interstitial nephritis in five patients. Antinuclear antibody (ANA) was found in 16 patients, but none of the 14 patients tested had antibodies to DNA. Tests for antibodies to myeloperoxidase (anti-MPO) and antibodies to neutrophil cytoplasm antigen (ANCA) were performed by ELISA. Twelve of the 14 patients tested had anti-MPO; five of these 14 patients had ANCA, while one had borderline levels. These findings suggest that hydralazine facilitates the induction of a systemic disease with multiple autoantibody production.


High frequency of myelomonocytic tumors in aging E mu L-myc transgenic mice. Transgenic mice that contain constructs of the L-myc gene under the transcriptional control of the immunoglobulin heavy chain enhancer (E mu) develop thymic hyperplasia and are predisposed to T cell lymphomas. Here we describe a second form of malignancy that occurs in aging E mu L-myc transgenic mice. The mean latency period for the development of this malignancy is longer compared with the E mu L-myc T cell lymphomas but the overall incidence is increased threefold. The histopathological morphology is that of a highly malignant mesenchymal neoplasm that closely resembles human fibrous histiocytoma. The tumor cells were classified as myelomonocytic on the basis of several lineage-specific markers and the lack of rearrangements of the immunoglobulin heavy chain and the T cell receptor beta loci. Cultured tumor cells produce macrophage colony-stimulating factor (M-CSF) protein and express the M-CSF receptor, suggesting the involvement of an autocrine loop in this malignancy. Similar to the E mu L-myc T cell lymphomas, these tumors show high-level transgene expression but no detectable levels of endogenous c-myc mRNA, directly implicating the deregulated expression of L-myc in the generation of this malignancy. E mu L-myc myelomonocytic tumors show consistent trisomy of chromosome 16, implicating this as a secondary event in the development of this tumor. In the light of recent findings that L-myc is expressed in human myeloid leukemias and in several human myeloid tumor cell lines, the results described here might implicate L-myc in the development of naturally occurring myeloid neoplasias.


Stabilization of the bioactivity of tumor necrosis factor by its soluble receptors. The receptors for tumor necrosis factor (TNF) exist in cell-associated as well as soluble forms, both binding specifically to TNF. Since the soluble forms of TNF receptors (sTNF-Rs) can compete with the cell-associated TNF receptors for TNF, it was suggested that they function as inhibitors of TNF activity; at high concentrations, the sTNF-Rs indeed inhibit TNF effects. However, we report here that in the presence of low concentrations of the sTNF-Rs, effects of TNF whose induction depend on prolonged treatment with this cytokine are augmented, reflecting an attenuation by the sTNF-Rs of spontaneous TNF activity decay. Evidence that this stabilization of TNF activity by the sTNF-Rs follows from stabilization of TNF structure within the complexes that TNF forms with the sTNF-Rs is presented here, suggesting that the sTNF-Rs can affect TNF activity not only by interfering with its binding to cells but also by stabilizing its structure and preserving its activity, thus augmenting some of its effects.


Biochemical evidence for the rapid assembly and disassembly of processed antigen-major histocompatibility complex class II complexes in acidic vesicles of B cells. Helper T cell recognition of antigen requires that it be processed within antigen-presenting cells (APC) to peptide fragments that subsequently bind to major histocompatibility complex (MHC) class II molecules and are displayed on the APC surface. Heretofore, processed antigen-MHC class II complexes have been detected by functional assays, measuring the activation of specific T cells. We now report direct, biochemical evidence for the assembly of processed antigen-MHC class II complexes within splenic B cells as APC. The I-Ek MHC class II molecules were immunoprecipitated from B cells that had processed the model protein antigen cytochrome c radiolabeled across its entire length by reductive methylation of lysine residues and covalently coupled to Ig-specific antibodies, allowing internalization after binding to surface Ig. Our previous studies showed that I-Ek immunoaffinity purified from B cells that had processed cytochrome c contains functional processed antigen--MHC class II complexes and that approximately 0.2% of the I-Ek molecules are specifically associated with one of two predominant processed antigenic fragments. Here we show that these complexes are rapidly assembled, within 30-60 min after antigen binding to surface Ig on splenic B cells. Maximal numbers of complexes are assembled by 2 h in a process that is sensitive to acidic vesicle inhibitors but not to inhibitors of protein synthesis. The processed antigen-I-Ek complexes have a relatively short half-life of 2-4 h and are disassembled or degraded within 8 h after antigen is first internalized. The disassembly or degradation of the processed antigen-I-Ek complexes requires acidic vesicle function, and in the presence of an acidic vesicle inhibitor the complexes are long lived. Thus, using a biochemical assay to monitor processed antigen-I-Ek complexes, we find that, in B cells, processed antigen is relatively rapidly associated in acidic vesicles with preexisting MHC class II molecules, and the complexes are disassembled 4-6 h later in processes that also require acid vesicle function.


Long-term follow-up on National Cancer Institute Phase I/II study of glioblastoma multiforme treated with iododeoxyuridine and hyperfractionated irradiation. We report the results of the final phase I/II program in glioblastoma (GBM) multiforme patients using only hyperfractionated irradiation and intravenous iododeoxyuridine (IdUrd). For a decade we investigated halogenated pyrimidine radiosensitizers in an effort to exploit the potential for differential uptake of thymidine analogs between proliferating tumor and normal brain tissues. Trials began with bromodeoxyuridine (BrdUrd) but were changed to IdUrd when the latter proved less photosensitizing. A series of dose-escalating pilot trials led to treatment at a maximum-tolerated dose (MTD) of IdUrd of 1,000 mg/m2/d for two separate 14-day courses, one during the initial radiation field and one during the cone down. The radiotherapy also evolved over time and was hyperfractionated in all cases reported. Over 5 years we accrued 45 patients into the final hyperfractionated, 1,000 mg/m2/d scheme. We report here results on only the patients with minimum follow-up of 1 year (90% had at least 2 years of follow-up) or until death. The results do not indicate a significant benefit for use of sensitizers, as compared with other contemporary and aggressive types of radiation treatment. The median survival has been 11 months, with a 2-year actuarial survival of 9%. As yet, there are no survivors at 3 years. Tumor biopsies at craniotomy showed relatively low sensitizer incorporation. The failure of radiosensitizers combined with radiation therapy to show major benefit may be due to patient selection but appears also to be related to the combined problems of poor drug penetration/uptake into tumor, tumor-cell heterogeneity, and a high inherent cellular radioresistance of GBM.


Randomized study of cyclophosphamide, doxorubicin, and vincristine versus etoposide and cisplatin versus alternation of these two regimens in extensive small-cell lung cancer: a phase III trial of the Southeastern Cancer Study Group. The trial was undertaken to determine (1) the relative efficacy/toxicity of two commonly used combination chemotherapy regimens in patients with extensive small-cell lung cancer (SCLC) and (2) whether the rapid alternation of these two regimens could provide superior therapeutic results compared with either regimen alone. In this phase III trial, 437 eligible patients were stratified by performance status (PS) and sex and were randomly assigned to receive either 12 weeks of cisplatin and etoposide (EP); 18 weeks of cyclophosphamide, doxorubicin, and vincristine (CAV); or 18 weeks of alternation of these two regimens (CAV/EP). There were no significant differences in treatment outcome for EP, CAV, or CAV/EP in terms of response rate (61%, 51%, 59%, respectively), complete response rate (10%, 7%, 7%, respectively), or median survival (8.6 months, 8.3 months, 8.1 months, respectively), with a non-statistically significant trend toward a longer median time to progression with alternating therapy (4.3 months, 4.0 months, 5.2 months, respectively). Crossover second-line chemotherapy given at progression produced low response rates and short survival, regardless of the regimen used. Myelosuppression was the dose-limiting toxicity for all patients, although the pattern and severity differed among the treatment arms. The combination regimens EP and CAV can be considered equivalently effective induction therapies in extensive SCLC, and these two regimens are, to some degree, crossresistant. Alternating therapy provides no therapeutic advantage compared with the use of either of these regimens alone and should not be considered as standard treatment in this clinical setting.


Prolonged administration of oral etoposide in non-small-cell lung cancer: a phase II trial. The trial was undertaken to investigate the activity and toxicity of a prolonged schedule of oral etoposide in the treatment of advanced non-small-cell lung cancer (NSCLC). Between March 1989 and August 1990, 25 patients with advanced NSCLC were treated with oral etoposide 50 mg/m2/d for 21 consecutive days, repeated every 28 to 35 days. The median patient age was 60 years (range, 38 to 84 years); male:female ratio was 12:13. Eight patients had stage IIIB disease; 17 had stage IV. Seventy-six percent of patients had Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. No patient had received previous chemotherapy with standard agents; nine patients had received previous or concurrent radiation therapy. Plasma etoposide concentrations were measured to estimate etoposide bioavailability and kinetics. Five of 22 patients (23%; 95% confidence interval [CI], 10% to 43%) had partial responses. Median response duration was 5 months (range, 2 to 6 months). Four of five responders were female. Besides alopecia, which occurred in all patients, myelosuppression was the most common toxicity, but was mild or moderate in most patients. Median leukocyte nadir during course 1 was 3,200/microL; only four of 69 courses produced a leukocyte nadir less than 1,000/microL. Severe thrombocythemia (less than 75,000/microL) did not occur. Gastrointestinal toxicity was uncommon. Median peak etoposide concentration was 3.4 micrograms/mL. A mean serum etoposide concentration greater than 1 microgram/L was maintained for more than 13 hours; the plasma concentration-time curve (AUC) was estimated to be 90% of that predicted after an identical dose of etoposide given intravenously. Etoposide given by this dose and schedule has moderate activity as first-line systemic therapy for advanced NSCLC. In previously untreated patients, chronic oral etoposide is well tolerated, and incorporation into combination regimens should be feasible. Etoposide bioavailability may be increased at lower oral doses.


Phase I-II study of high-dose epirubicin in advanced non-small-cell lung cancer. A phase I multicenter trial was performed to determine the maximum-tolerated dose (MTD) of epirubicin, given on 3 consecutive days every 3 weeks to previously untreated patients with advanced non-small-cell lung cancer (NSCLC). After appropriate staging and a baseline multiple-gated angiogram (MUGA) scan, at least four patients were entered at each dose level, starting at 35 mg/m2 of epirubicin given intravenously (IV) daily for 3 days (105 mg/m2) and escalating by 5 mg/m2 per injection in each dose level (15 mg/m2 per course). Epirubicin was administered up to a maximum dose of 60 mg/m2/d for 3 days (180 mg/m2). The MTD was determined to be 55 mg/m2/d for 3 days (165 mg/m2) after treating a total of 35 (33 assessable) patients. Nadir granulocyte counts and associated febrile episodes comprised the dose-limiting toxicity, but there were no treatment-related deaths. A phase II trial was performed using a dose of 50 mg/m2/d for 3 days (150 mg/m2) every 3 weeks with no dose escalation, but with dose reduction for toxicity as required. A total of 30 patients were entered onto this phase of the study. The major toxicity, as in the phase I trial, was neutropenia with five febrile episodes, again with no treatment-related deaths. An overall response rate of 12 of 63 (19%) was noted in the combined patient population of the phase I-II trial, with 95% confidence intervals of 10% to 31%. When the response rate was analyzed by histology, only one of 17 (6%) patients with squamous histology, as compared with 11 of 46 (24%) with non-squamous histology, responded, but this did not reach statistical significance (P = .15). High-dose epirubicin is tolerable and is an active single agent in NSCLC. It should be combined with relatively nonmyelosuppressive agents such as cisplatin to try to obtain higher response rates and extend the survival in this disease.


Radionuclide hysterosalpingography with technetium-99m-pertechnetate: application and radiation dose to the ovaries. Although radionuclide hysterosalpingography (RNHSG) has been suggested as an efficient procedure for assessing function of fallopian tubes, the radiation dose to the ovaries was addressed as an important issue to be taken into consideration. We describe a modified method of RNHSG, calculating the radiation dose to the ovaries. A small dose of approximately 18.5 MBq (0.5 mCi) of [99mTc]pertechnetate was administered directly into the uterine cavity without overpressure. The accuracy of the method was 84.5% as compared with the contrast hysterosalpingography. The estimated average dose to the ovaries was 0.057 mGy/MBq (0.21 rad/mCi) or 1.08 mGy (108 mrad) per study. RNHSG is an accurate method for functional study of fallopian tube patency with low radiation dose.


Postprandial lipid response following a high fat meal in rats adapted to dietary fiber. Rats were adapted to diets containing 5 g/100 g cellulose (CL), 5 g/100 g oat bran fiber (OB) or 5 g/100 g psyllium husk (Psy) for 4 wk. Following a 12-h fast, animals were either killed at 0 h (baseline) or fed 4.5 g of a test meal that provided 50% energy from fat, then killed at 1, 4 or 6 h postprandially. Fasting plasma and HDL cholesterol concentrations were lower in Psy-fed animals than in rats fed either CL or OB. Plasma triglycerides increased significantly from baseline (0 h) in all groups but did not differ among diet treatments. Increases in triglyceride content of the treatments. Increases in triglyceride content of the chylomicron/VLDL fraction occurred in the CL- and OB-fed groups and in the HDL fraction of the Psy-fed group during the postprandial period. In unfed animals the hepatic and intestinal levels of apolipoprotein A-IV mRNA were higher in the CL-fed group than in the groups fed OB and Psy. Apolipoprotein B mRNA was higher in the intestine of the OB-fed group than in the groups fed CL and Psy and had a significant gradient along the small intestine, increasing in the distal third. The results suggest that chronic consumption of fiber is less likely to modify the acute plams triglyceride response to a fat-containing test meal than if a fiber supplement is incorporated into the meal.


Dietary soluble fiber and cholesterol affect serum cholesterol concentration, hepatic portal venous short-chain fatty acid concentrations and fecal sterol excretion in rats. Sprague-Dawley rats were fed diets containing 7.5% dietary fiber as cellulose (control), pectin, psyllium or oat bran with or without 0.3% added cholesterol for 3 wk. Among rats fed cholesterol, liver total lipid and cholesterol concentrations were significantly lower in groups fed pectin, psyllium and oat bran compared with cellulose-fed controls. Cholesterol feeding resulted in significantly greater liver cholesterol in rats fed cellulose, psyllium and oat bran but not in those fed pectin. Among rats fed cholesterol, total serum cholesterol levels were significantly lower in those fed pectin than in those fed psyllium, oat bran or cellulose. When cholesterol was fed, the oat bran-fed group had significantly higher butyrate and the pectin-fed group had significantly higher propionate concentrations in the hepatic portal vein than did cellulose-fed controls. The groups fed psyllium, oat bran and pectin all had significantly higher fecal neutral sterols than did the cellulose-fed group when cholesterol was fed. Without dietary cholesterol only pectin-fed rats had significantly higher fecal excretion of neutral sterols than those fed cellulose. Dietary fiber did not influence fecal acidic sterol excretion. However, the addition of cholesterol to these fiber diets was accompanied by a significantly higher bile acid excretion than that of animals fed cellulose without cholesterol. The results of this study indicate that soluble dietary fibers may exert their hypocholesterolemic effect by increasing excretion of fecal neutral sterols.


Various dietary fibers have different effects on lipase-catalyzed hydrolysis of tributyrin in vitro. The ability of various dietary fibers to impede lipase-catalyzed hydrolysis of tributyrin was studied in vitro. Conditions (temperature, kind and concentration of constituents, pH, agitation) were chosen to mimic, as closely as possible, those prevailing in the human duodenum. Lipolysis was monitored at pH 6.0 and 37 degrees C using a constant pH titrimeter. Some fibers inhibited lipolysis (red wheat bran, white wheat bran, oat bran and sugarbeet fiber), whereas most did not (psyllium seed, pectin LM 12CG, carrageenan, carboxymethylcellulose, gum arabic, and pectin slow set). Water extracts of the fibers accounted for 32-41% of the inhibitory effect of the two wheat brans on lipolysis and 100% of the inhibitory effect of oat bran.


The metabolizable energy of diets differing in dietary fat and fiber measured in humans. The metabolizable energy of two diets differing in fat and fiber content was measured in balance experiments in 42 adult male subjects. Subjects received each diet for 10 wk in a crossover design. Average fiber consumption from mixed sources (cereals, legumes, fruits and vegetables) while consuming the low fiber, high fat diet was 34 g/d and 64 g/d while consuming the high fiber, low fat diet. The percentages of energy from protein, fat and carbohydrate were 16, 18.5 and 65.5, respectively in the high fiber, low fat diet and 14.5, 36 and 49.5, respectively, in the low fiber, high fat diet. Seven-day composite collections of food, urine and feces were made during the 10th wk of the study. The freeze-dried food and fecal samples were analyzed for total energy content and for protein, fat, moisture, ash and carbohydrate. Urine samples were analyzed for nitrogen and energy content. The digestibility of the energy-containing nutrients was significantly lower when subjects were consuming high fiber, low fat vs. low fiber, high fat diets (95.4 vs. 97.0, carbohydrate; 92.5 vs. 95.5, fat; 83.7 vs. 89.4, protein; and 91.4 vs. 94.3, energy.


Epithelia-damaging virus infections affect vitamin A status in chickens. The effect of infection with infectious bronchitis virus (IBV) and reovirus (RV) on vitamin A status was investigated in chickens with a normal or marginal intake of vitamin A. At the age of 4 wk, chickens were infected with either IBV or RV, primarily affecting the respiratory or intestinal tract, respectively. Both viruses lowered plasma retinol levels significantly. The effect was more pronounced in chickens fed a diet marginally deficient in vitamin A than in those fed a diet adequate in vitamin A. Concentrations of retinol-binding protein, transthyretin and albumin in RV-infected chickens were also significantly lower than in noninfected chickens fed the same diets; in chickens infected with IBV, there was no effect. These results suggest that the reduced vitamin A status of IBV-infected chickens could be attributed to increased rate of utilization by tissues. In RV infection, this mechanism could be involved but impaired absorption of nutrients (including vitamin A) and direct loss of nutrients via the intestinal tract could also be important.


Dietary fat and cholesterol modulate the plasma lipoprotein distribution and production of pigment or cholesterol gallstones in hamsters. To evaluate the impact of key dietary factors on plasma lipoproteins and gallstone induction, male Syrian hamsters were fed either cholesterol and fat-supplemented purified diets containing glucose or lactose, or cholesterol and fat-free diets with or without fiber, for 13 wk. Fat-supplemented hamsters were hyperlipidemic in comparison to those fed fat-free diets. The former group revealed a greatly expanded VLDL fraction, whereas a normal HDL2 pool predominated in the latter group. Plasma fatty acids indicated that hamsters fed the fat-free diet were essential fatty acid deficient whilst the hamsters fed the fat-supplemented diet were subnormal in essential fatty acids. Ninety-three percent of the hamsters fed the fat-supplemented diet had gallstones (mostly cholesterol), whereas 62% of hamsters fed the fat-free diet had gallstones (almost all pigmented). Lactose increased cecal weight and prevented pigment stone formation in the fat-supplemented hamsters, whereas adding fiber to the fat-free diet contributed essential fatty acids, eliminated cholesterol stones and enhanced pigment stone formation. Thus, diets containing casein, rice flour, glucose and fiber with minimal essential fatty acids but no cholesterol promoted pigment stones (associated with a normal lipoprotein profile); a low fat diet limited in essential fatty acids but containing cholesterol and lactose, promoted cholesterol gallstones (associated with an expanded VLDL pool).


A novel class of cardiotonic agents: synthesis and biological evaluation of 5-substituted 3,6-dihydrothiadiazin-2-ones with cyclic AMP phosphodiesterase inhibiting and myofibrillar calcium sensitizing properties. As part of a search for new cardiotonic agents significantly sensitising the myocardial contractile proteins to calcium, together with cardiac cyclic AMP-PDE inhibitory activity, we have discovered that novel 5-substituted 3,6-dihydrothiadiazin-2-ones may fulfill both properties. The sensitising effect of the contractile proteins to calcium, assessed by the shift in the calcium sensitivity of canine cardiac myofibrillar magnesium-dependent ATPase, is determined by steric and electronic requirements. The requirements for phosphodiesterase inhibition, especially that of a near-planar arrangement for the phenyl and thiadiazin-2-one ring are consistent with those already described for analogous pyridazinones. The synthesis and structure-activity relationships are discussed.


Synthesis, characterization, and biological evaluation of a novel class of N-(arylethyl)-N-alkyl-2-(1-pyrrolidinyl)ethylamines: structural requirements and binding affinity at the sigma receptor. By synthesizing and testing a part-structure, N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine (3), derived from our previously reported high affinity sigma receptor ligands (1S,2R)-(-)-N-[2-(3,4-dichlorophenyl)-ethyl]-N-methyl-2-(1- pyrrolidinyl)cyclohexylamine [(-)-2] and (+)-2, we have identified a novel class of superpotent (subnanomolar affinity) sigma ligands specific for the sigma receptor labeled by [3H]-(+)-3-PPP. When 3 was tested for its capacity to displace [3H]-(+)-3-PPP from guinea pig brain membranes, it exhibited a Ki of 0.34 nM, which is better than either of its parent compounds (-)-2 (Ki = 1.3 nM) and (+)-2 (Ki = 6.0 nM). Other compounds related to 3 such as N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-homopiperidinyl)ethy lamine (19) exhibited Ki = 0.17 nM [( 3H]-(+)-3-PPP). The determinants for high sigma receptor affinity of 3 were examined by manipulation of this structure in a number of different ways. The high efficacy of these compounds for the sigma receptor, their relative chemical simplicity and ease of synthesis, and their high degree of selective identifies N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine (3) and related compounds as a highly promising base for determination of the functional role of sigma receptors as well as the development of novel therapeutic agents.


Synthesis, antinociceptive activity, and opioid receptor profiles of substituted trans-3-(decahydro- and octahydro-4a-isoquinolinyl)phenols. A series of trans-3-(6- and 7-substituted-decahydro-4a-isoquinolinyl)phenols and trans-3-(octahydro-4a-isoquinolinyl)phenols have been synthesized as potential opioid analgesics. Using a combination of in vitro and in vivo test systems, the receptor profiles of selected compounds have been assessed and in some instances distinguish between mu- and kappa-receptor agonists. In general, introduction of a 6-exocyclic methylene group into the trans-3-(decahydro-4a-isoquinolinyl)phenol system enhanced both antinociceptive activity and kappa-opioid receptor selectivity. For each series, analogues bearing an N-cyclopropylmethyl substituent exhibited greater kappa-receptor selectivity while N-methyl derivatives showed greater mu-receptor selectivity. The 7-substituted compounds (3b) were significantly less potent antinociceptive agents than their 6-substituted counterparts (3a), the octahydroisoquinoline analogues exhibiting intermediate activity. The axial 8-methyl-6-exocyclic methylene isoquinoline (20) is the most potent compound in the mouse abdominal constriction assay (ED50 = 0.05 mg/kg sc), whereas the equatorial 8-methyl isomer (16) was significantly less potent (ED50 = 3.3 mg/kg sc).


Synthesis and antibacterial activity of new tetracyclic quinolone antibacterials. A series of 8-substituted-9,1-(epoxymethano)-7-fluoro-5-oxo-5H- thiazolo[3,2-a]quinoline-4-carboxylic acids having a novel tetracyclic structure was synthesized and tested for antibacterial activity. The nature of the heteroatom (N, O, or S) substituted at the 8-position had little influence on the antibacterial activity. Among the six pyrrolidinyl derivatives and the five piperazinyl derivatives, the 8-(3-hydroxy-1-pyrrolidinyl) derivative 6h and the hydrochloride of the 8-(4-methyl-1-piperazinyl) derivative 6l showed the most potent activity against both Gram-positive and Gram-negative bacteria. Against nalidixic acid resistant strains, isolated from Escherichia coli KC-14, compound 6h was less potent than 6l. Replacement of the piperazinyl nitrogen atom by a carbon atom, an oxygen atom, or a sulfur atom (corresponding to the piperidino, morpholino, or thiomorpholino group, respectively) enhanced the activity against Gram-positive bacteria, but reduced the activity against Gram-negative bacteria. Compound 6l also showed potent in vivo antibacterial activity against Gram-positive and Gram-negative bacteria, and did not cause convulsions in mice with the concomitant administration of fenbufen. Replacement of the carboxy group by a sulfonic acid group in 6l resulted in a complete loss of antibacterial activity.


Beta-proline analogues as agonists at the strychnine-sensitive glycine receptor. 3-Carboxy-3,4-dehydropyrrolidine was found to bind with affinity equal to that of glycine in a [3H]strychnine binding assay. Simple substitution of the 1-, 2-, 4-, or 5-position resulted in marked loss of affinity. A decline in affinity was also found upon enlargement, contraction, or saturation of the 5-membered ring. However, beta-proline and azetidine-3-carboxylic acid retained significant binding affinity. Despite its good affinity in [3H]strychnine binding, 3-carboxy-3,4-dehydropyrrolidine showed only weak agonist activity in intracellular recordings of cultured murine spinal cord neurons. This apparent lack of correlation between binding and functional results is discussed in light of the current models of the strychnine-sensitive glycine receptor.


Substituted 4,6-diaminoquinolines as inhibitors of C5a receptor binding. The anaphylatoxin C5a is implicated in a number of inflammatory diseases. It is a highly cationic protein with 13 of 74 amino acids being either arginine or lysine. A search focusing on positively charged molecules, particularly amine-containing functionalities, led to the discovery of substituted 4,6-diaminoquinolines 1 [N,N'-bis(4-amino-2-methyl-6-quinolyl)urea] and 7 [6-N-(2-chlorocinnamoyl)-4,6-diamino-2-methylquinoline] as inhibitors of C5a receptor binding. These two compounds inhibited the binding of radiolabeled C5a to its receptor isolated from human neutrophils with IC50's = 3.3 and 12 micrograms/mL, respectively. Our efforts to enhance their potencies by chemical modification revealed a narrow profile of potency for effective C5a receptor binding inhibition.


Potential antitumor agents. 64. Synthesis and antitumor evaluation of dibenzo[1,4]dioxin-1-carboxamides: a new class of weakly binding DNA-intercalating agents. A series of substituted dibenzo[1,4]dioxin-1-carboxamides has been synthesized and evaluated for in vitro and in vivo antitumor activity. The required substituted dibenzo[1,4]dioxin-1-carboxylic acids were prepared by a variety of methods. No regiospecific syntheses were available for many of these, and separation of the mixtures of regioisomers obtained was sometimes difficult. The dibenzo[1,4]dioxin-1-carboxamides are active against wild-type P388 leukemia in vitro and in vivo, with structure-activity relationships resembling those for both the acridine-4-carboxamide and phenazine-1-carboxamide series of DNA-intercalating antitumor agents. In all three series, substituents placed peri to the carboxamide sidechain (the 5-position in the acridines, and the 9-position in the phenazines and dibenzo[1,4]dioxins) enhance activity and potency. The 9-chlorodibenzodioxin-1-carboxamide was also curative against the remotely sited Lewis lung carcinoma. Several of the compounds showed much lower levels of cross-resistance to the P388/AMSA line than classical DNA-intercalating agents, which suggests that their primary mechanism of action may not be via interference with topoisomerase II alpha. This is of interest with regard to the development of drugs to combat resistance mechanisms which arise by the expression of the topo II beta isozyme.


Structure-function studies of peptides inhibiting the ribonucleotide reductase activity of herpes simplex virus type I. Ac-Tyr298-Ala299-Gly300-Thr301-Val302-I le303-Asn304-Asp305-Leu306-OH (Ac-VZV R2-(298-306)) represents the acetylated form of the C-terminus of varicella-zoster virus (VZV) ribonucleotide reductase subunit 2 (R2). This peptide possesses a high degree of homology with the C-terminus nonapeptide of the herpes simplex virus (HSV) type I and II ribonucleotide reductase R2 protein and is 15 times more potent than the latter in its in vitro inhibition of HSV-1 reductase activity. Accordingly, a new series of analogues based on this structure was studied in vitro. The replacement of Asp305 by Asn, Glu, Gln, Ser, or Cys; of Asn304 by Gln or Ser; of Ile303 and Val302 by D-Val; and of Tyr298 by Cha induced an important loss of inhibitory potency. The substitution of Asn304 by Asp; of Thr301 by Cys, Ser, or Val; of Gly300 by Ala or Val; of Ala299 by Val; or of Tyr298 by homoPhe, 4'-fluoro-Phe, 4'-chloro-Phe, 3'-iodo-Tyr, Me-Tyr, or For-Trp led to a moderate decrease of the Ac-VZV R2-(298-306) potency. The replacement of Val302 by Ile; Ala299 by Cys, Ser, or Thr; or the insertion of a six- or eight-carbon chain between Tyr298 and the NH2 terminus either preserved or slightly increased the inhibitory potency of Ac-VZV R2-(298-306). Finally, the substitution of Tyr298 by Trp or the addition of 4'-nitro-Phe at the amino terminus resulted in a 3-fold increase of potency. Altogether, these results stress the importance of the structural integrity of the minimum active core 302-306 in preserving the inhibitory potency and suggest that further studies on monosubstitutions could be directed at the portion 298-301 of the peptide.


Synthesis of novel 2-phenyl-2H-pyrazolo[4,3-c]isoquinolin-3-ols: topological comparisons with analogues of 2-phenyl-2,5-dihydropyrazolo[4,3-c]quinolin-3(3H)-ones at benzodiazepine receptors. Based on the topology of pyrazoloquinolinones 10-12, a series of 2-phenyl-2H-pyrazolo[4,3-c]isoquinolines 6a-d, 7a-d, 8, and 9 have been synthesized and evaluated for their ability to inhibit radioligand binding to benzodiazepine receptors (BzR). Modification of the hydrogen bonding donor and acceptor characteristics of the NH and C = O functionalities of the pyrazoloquinolinones 10-12 resulted in ligands with dramatically reduced affinities (IC50 much greater than 2 microM) for BzR. The low affinities of 6a-d, 7a-d, 8, and 9 are consistent with the involvement of the NH function present on diverse classes of inverse agonists (beta-carbolines, diindoles, and pyrazoloquinolinones) with a hydrogen bond acceptor site (A2) on the binding protein. Moreover, it supports the involvement of the carbonyl function of the pyrazoloquinolinones and the pyridine nitrogen atom of beta-carbolines and diindoles with a hydrogen bond donor site (H1). Finally, the results from this work indicate that a simultaneous interaction at both hydrogen bond donor (H1) and acceptor sites (A2) at BzR is required for high affinity binding of inverse agonists.


Detection of human papillomavirus in squamous neoplasm of the penis. Infection of the external human urogenital system with human papillomavirus has been implicated with the development of genital cancer. A modified polymerase chain reaction technique has been used to evaluate type specific deoxyribonucleic acid (DNA) sequences of unique E6 to E7 transforming regions of human papillomavirus genomes (types 6b/11, 16 and 18) in a morphological spectrum of in situ (carcinoma in situ) and invasive neoplasm of the penis. We studied 15 examples of carcinoma in situ [7 bowenoid and 8 nonbowenoid (squamoid or simplex)], 11 of invasive squamous carcinoma, 1 of verrucous carcinoma, 2 of verrucous hyperplasia, 1 of urethral adenocarcinoma and 1 solitary papilloma. Viral DNA was not detected in any of the nonbowenoid specimens of carcinoma in situ, the verrucous carcinoma, the adenocarcinoma or the papilloma of the penis. Human papillomavirus types 6b/11 and 18 specific sequences also were not detectable in any of the specimens examined. However, all 7 of the bowenoid forms of carcinoma in situ were positive for human papillomavirus type 16 DNA. The presence of human papillomavirus type 16 was also detected in 9 of 11 invasive squamous carcinomas and in both verrucous hyperplasias. Our results confirm that the bowenoid forms of intraepithelial neoplasms and most invasive squamous carcinomas contain the E6 to E7 portion of type 16 human papillomavirus genome.


Secondary surgery in patients with malignant germ cell tumors. A total of 102 men treated for germ cell tumor with chemotherapy containing cisplatin was referred for a secondary operation with signs of tumor in the retroperitoneum or chest. Of the patients 85 underwent laparotomy, 14 underwent thoracotomy and 3 had both operations. Residual tumors were completely resected in 66 patients and incompletely resected in 30, while no tumor was found in 6. The resected specimen was malignant in 18 patients, of whom 11 had complete removal of all malignant tissue. All patients with malignancy in the resected specimen received further chemotherapy. Long-term disease-free status was obtained in 75% of those patients who had a complete resection, compared with 14% in the group with incomplete resection. There was no evidence of malignant disease at operation in 78 patients but 5 of them later died of the disease. Malignant tissue was present in the residual tumor in only 1 of 15 patients whose primary tumor was seminoma alone. Resection was attempted in 14 patients despite abnormal tumor markers preoperatively. Only 5 of these patients achieved a disease-free status and 2 of them died later of malignant disease. Over-all 79 of the 102 patients are without evidence of disease (medium postoperative observation 23 1/2 months). We conclude that a secondary operation constitutes an important part of the treatment of patients with germ cell cancer.


Retroaortic left renal vein in testicular cancer patient: potential staging and treatment pitfall. A 20-year-old man was diagnosed with a left mixed germ cell testicular tumor and clinical staging with computerized tomography suggested left para-aortic subhilar retroperitoneal adenopathy. The patient received 4 cycles of cisplatin, vinblastine and bleomycin chemotherapy but the mass in the left renal hilus area remained unchanged. Subsequent retroperitoneal lymphadenectomy revealed the mass to be a retroaoritc left renal vein type 2. Further confusion occurred during followup in differentiating this anomaly from recurrent neoplasm necessitating evaluation by magnetic resonance imaging. Retroaortic left renal vein represents a potential imaging pitfall in testicular cancer that may facilitate suboptimal staging, treatment and followup.


Tetrodotoxin protects against acute ischemic renal failure in the rat. Tetrodotoxin has been reported to cause prolonged systemic hypotension without resultant ischemic damage. We tested its ability to protect the kidney during 60 minutes of warm ischemia in uninephrectomized rats. Protection was observed when tetrodotoxin was given intravenously at two microgram./kg. and four microgram./kg. as assessed by serial plasma blood urea nitrogen and creatinine measurements over two weeks. Tetrodotoxin was protective when given immediately before or immediately after the ischemic period. The renal protection of tetrodotoxin was not due to its effects on renal nerves as renal denervation did not protect the kidney from the ischemic damage. The renal protective effects of four microgram. tetrodotoxin/kg. were similar to those of four mg. captopril/kg. but the combination of the two was paradoxically without effect. We tested whether tetrodotoxin and captopril chemically antagonized each other, but in the presence of tetrodotoxin, captopril was still a potent inhibitor of the conversion of angiotensin I to angiotensin II. These results indicate that tetrodotoxin could be useful in elucidating the sequence of events associated with ischemic-reperfusion renal injury and in identifying ways of preserving renal function during renal surgery.


Therapeutic aspects of myelodysplastic syndromes in chronic phase. Myelodysplastic syndromes (MDS) include hemopoietic cytopenias of different origin, which are usually refractory to treatment. Therefore MDS patients should generally be treated conservatively. Transfusions of packed red cells (given in a strict regimen to minimize the risk for secondary hemochromatosis) may be sufficient to maintain a good quality of life. Indications for cytotoxic treatment include signs of progression of the disease. In patients with symptomatic cytopenias low-dose cytarabine (ara-C) should be tried. It is essential then to monitor each patient individually and to avoid fixed treatment schedules. Standard (high-dose) chemotherapy in MDS, is associated with a high mortality and a low response rate, and should be considered only in younger patients with advanced MDS. Allogeneic bone marrow transplantation (BMT) may be offered to younger MDS patients, when a suitable donor is available. Treatment with differentiation inducers has not met with expectations and should not be used outside clinical trials at the present. The use of recombinant hemopoietic growth factors (GF) seems promising. GF, like GM-CSF, G-CSF, IL-3, and erythropoietin, can be used either alone or in combinations, to support failing peripheral blood values, and decrease the risk for lethal complications. GF can also be given together with chemotherapy, in an effort to make the leukemic clonogenic cells more susceptible to cytotoxic drugs. Other treatments for MDS include: IFN-alpha and etoposide, with responses primarily in chronic myelomonocytic leukemia; hem arginate, whose role is still not clear; and corticosteroids, but only in carefully selected cases.


PAF receptor blockade inhibits lung vascular changes in the rat monocrotaline model. We recently reported that platelet-activating factor (PAF) levels increased in lung tissue after 1 subcutaneous injection of monocrotaline (MCT) (which causes lung injury), and, further, that treatment with PAF antagonists reduced pulmonary hypertension in this chronic lung injury rat model [15]. In the present study, we examined the effect of WEB 2170, a specific PAF antagonist, on MCT-induced pulmonary vascular remodeling. At 3 weeks after MCT injection, pulmonary hypertension in the animals was associated with an increase in the vessel wall thickness of the muscular arteries, reduction in number of peripheral arterioles, and right ventricular hypertrophy. In WEB 2170-treated rats, these changes were significantly less severe when compared with those observed in MCT-treated rats. In MCT-treated rats, there were significant increases in in vitro [3H]thymidine incorporation and accumulation of hydroxyproline in the lung tissue, and these changes were inhibited by WEB 2170 treatment. Our results suggest that PAF or a PAF-dependent sequence of events is involved in MCT-induced lung vascular remodeling.


Metastatic bronchioloalveolar carcinoma and metastatic adenocarcinoma of the lung: comparison of clinical manifestations, chemotherapeutic responses, and prognosis. Between 1975 and 1985, 25 patients with metastatic bronchioloalveolar carcinoma and 223 patients with metastatic adenocarcinoma of the lung received experimental cisplatin-based chemotherapy at the Mayo Clinic. The chemotherapeutic response rates were 32% and 33%, respectively. The median times to progression of disease were identical (3 months in both groups). The median survival times were 4 months and 6 months, respectively. Metastatic bronchioloalveolar carcinoma is an aggressive disease that is associated with a poor prognosis, similar to metastatic adenocarcinoma of the lung.


Enhanced sensitivity to naltrexone is associated with an up-regulation in GABA receptor function. Rats were made sensitive to the effects of the opioid antagonist naltrexone by treating them once weekly with cumulative doses of the drug (1, 3, 10, 30 and 100 mg/kg). Sensitization was monitored by measuring salivation following naltrexone administration. During the first week of treatment, no salivation was noted following any dose of naltrexone. Over a period of 8 weeks, however, increasing amounts of salivation were noted, with the most salivation occurring at the higher doses. Animals treated for 8 weeks with saline never salivated following injections. Following the development of sensitivity to naltrexone, the rats were sacrificed and their brains were assayed for GABA receptor function. GABA-stimulated chloride uptake, a measure of GABA receptor function, was unchanged in the cortex, but was increased in the cerebellum. These results suggest that the effects of naltrexone on cerebellar GABA receptors may be involved in the development of enhanced sensitivity to opioid antagonists.


Identification of cultured cells selectively expressing Y1-, Y2-, or Y3-type receptors for neuropeptide Y/peptide YY. Neuropeptide Y (NPY) and peptide YY (PYY) are homologous 36 amino acid amidated peptides that often, but not always, exert similar actions and binding profiles. The present study of cultured cells confirms that both peptides as well as radioiodinated analogs, i.e. 125I-Bolton-Hunter-NPY (125I-BH-NPY) and 125I-peptide YY (125I-PYY), show high affinity to binding sites/receptors of the previously proposed Y1- and Y2-subtypes, selectively expressed by the human neuroblastoma cell lines, SK-N-MC and SK-N-BE(2), respectively. In contrast, bovine adrenal chromaffin cells did not bind 125I-PYY, while displaying high affinity 125I-BH-NPY sites, and may therefore represent a cell type expressing a recently proposed Y3-type of (NPY-preferring) receptors. Several non-labeled fragments/analogs have been used in displacement experiments to further characterize the structural requirements for Y1-, Y2-, and Y3-type binding. In every instance, specific binding was reduced by addition of 5'-guanylylimidodiphosphate [Gpp(NH)p], indicating that the three receptor subtypes belong to the G-protein-coupled superfamily of receptors. Moreover, in both neuroblastoma cell lines, the peptides elicited, with appropriate orders of potency, reduction of forskolin-stimulated adenosine 3',5'-cyclic monophosphate (cAMP) accumulation. Finally, NPY-evoked 45Ca2+ influx was observed in SK-N-MC and in chromaffin cells. A common dual coupling mechanism of NPY/PYY receptors, i.e. to reduction of cAMP and to Ca2+ elevation, is therefore suggested to exist, although both phenomena could not be demonstrated in every cell type.


Biological profiles of highly potent novel endothelin antagonists selective for the ETA receptor. We describe novel potent endothelin (ET) antagonists that are highly potent and selective for the ETA receptor (selective to ET-1). Of the synthetic analogs based on ETA antagonist BE-18257A isolated from Streptomyces misakiensis (IC50 value for ETA receptor on porcine aortic smooth muscle cells (VSMCs); 1.4 microM), the compounds BQ-123 and BQ-153 greatly improved the binding affinity of [125I]ET-1 for ETA receptors on VSMCs (IC50; 7.3 and 8.6 nM, respectively), whereas they barely inhibited [125I]ET-1 binding to ETB receptors (nonselective with respect to isopeptides of ET family) in the cerebellar membranes (IC50; 18 and 54 microM, respectively). Associated with the increased affinity for ETA receptors, these peptides antagonized ET-1-induced constriction of isolated porcine coronary artery. However, there was a small amount of ET-1-induced vasoconstriction resistant to these antagonists, which paralleled the incomplete inhibition of [125I]ET-1 binding in the membrane of the aortic smooth muscle layer. These data suggest that the artery has both ETA and ETB receptors responsible for ET-1-induced vasoconstriction. The antagonists shifted the concentration-response curve to the right for ET-1 in the coronary artery, and increased the apparent dissociation constant in the Scatchard analysis of [125I]ET-1 binding on the VSMCs without affecting the binding capacity, indicative of the competitive antagonism for ETA receptor. In conscious rats, pretreatment with the antagonists markedly antagonized ET-1-induced sustained pressor responses in dose-dependent fashion without affecting ET-1-induced transient depressor action, suggesting that the pressor action is mediated by ETA receptors, while the depressor action is mediated by ETB receptors. In addition, pretreatment with the potent antagonists prevented ET-1-induced sudden death in mice. Thus, these potent ETA antagonists should provide a powerful tool for exploring the therapeutic uses of ETA antagonists in putative ET-1-related disorders.


Monokines inhibiting erythropoietin production in human hepatoma cultures and in isolated perfused rat kidneys. The blood level of erythropoietin (Epo) is often anomalously low in anemic patients with inflammatory or malignant diseases. Therefore, we studied effects of pure recombinant immunomodulatory peptides on Epo formation in cultures of the human hepatoma cell line, HepG2. Interleukin (IL)-1 beta, IL-1 alpha, and tumor necrosis factor alpha lowered Epo production with half-maximal inhibition at 2, 5, and 20 U/ml, respectively. IL-6, transforming growth factor beta 2 and interferon gamma did not inhibit. Furthermore, IL-1 beta (10 U/ml) proved to block Epo formation in isolated serum-free perfused rat kidneys. Proposedly, monokines play a role in the pathogenesis of Epo deficiency in various diseases.


Pharmacological evidence for the involvement of multiple calcitonin gene-related peptide (CGRP) receptors in the antisecretory and antiulcer effect of CGRP in rat stomach. We have investigated the effect of the C-terminal fragment of human calcitonin gene-related peptide (human-CGRP8-37), a CGRP antagonist, on alpha-CGRP and salmon Calcitonin (sCT)-induced inhibition of gastric acid secretion stimulated by pentagastrin (24 nmol kg-1 h-1 i.v.) and gastric lesions induced by acetylsalycilic acid (ASA; 25 mM) in rats anaesthetized with urethane. Close intra arterial infusion of alpha-CGRP (2-5 nmol kg-1) and sCT (5 nmol kg-1) produced a reduction in gastric acid hypersecretion induced by pentagastrin. The concomitant infusion with human-CGRP8-37 (10 nmol kg-1) reversed the effect of both agonists. ASA-ulcers were reduced in a dose-dependent manner by infusion of alpha-CGRP (1-2 nmol kg-1 i.a.), but not by sCT (10 nmol kg-1 i.a.). Human-CGRP8-37 at a dose of 10 nmol kg-1 i.a. was unable to reverse the alpha-CGRP antiulcer effect. An higher dose of human-CGRP8-37 (50 nmol kg-1 i.a.) showed agonistic properties reducing ASA ulcers. These results suggest that the inhibitory effects of alpha-CGRP on stimulated acid secretion and aspirin ulcers are mediated by different mechanisms and/or different receptors.


Pharmacological characterization of a novel muscarinic partial agonist, YM796, in transfected cells expressing the m1 or m2 muscarinic receptor gene. To investigate the pharmacological effect of a novel compound YM796, we performed radioligand binding experiments and correlative biochemical experiments using the transfected murine fibroblast B82 cells which expressed the m1 and m2 muscarinic receptor genes (cloned cell lines designated as LK3-3 and M2LKB2-2, respectively). [3H](-)methyl-3-quinuclidinyl benzilate [( 3H](-)MQNB) binding in these transfected cell lines was inhibited by different optical isomers of YM796 and other muscarinic drugs, atropine, pirenzepine, AF-DX 116, as well as selected agonists. (-)YM796, (+)YM796 and (+/-)YM796 inhibited [3H](-)MQNB binding in LK3-3 cells with Ki values of 16.4 microM, 30.1 microM and 21.8 microM and in M2LKB2-2 cells with Ki values of 52.0 microM, 108 microM and 77.1 microM, respectively. From functional assays we found the two isomers, (-)YM796 and (+)YM796 had different intrinsic activities for the M1 and M2 muscarinic receptors. (-)YM796 revealed agonistic activity: stimulation of [3H]IP1 accumulation in LK3-3 cells with an EC50 value of 26.5 microM, which was less efficacious (the Emax value was 5.6 times basal) than carbachol, a full agonist (the Emax value was 17.2 times basal). Interestingly, (-)YM796 did not show significant inhibition of cAMP formation in M2LKB2-2 cells except at extremely high concentrations (greater than 1mM). (+)YM796 exhibited no significant efficacy for the M1 and M2 muscarinic receptors. These results suggest that (-)YM796 represents a muscarinic partial agonist with functional selectivity for the M1 muscarinic receptors whereas (+)YM796 shows no efficacy for either M1 or M2 muscarinic receptors in these transfected cells.


Dynamic control of inositol 1,4,5-trisphosphate-induced Ca2+ release: a theoretical explanation for the quantal release of Ca2+. A theoretical model has been elaborated in order to describe the kinetics of Ca2+ release induced by inositol 1,4,5-trisphosphate (IP3). The model is based on the existence of a key molecule that controls the interconversion of open and closed forms of the Ca2+ channel. The model can quantitatively explain the previously obtained experimental observations that showed that a continuous IP3 stimulus leads to a biphasic Ca2+ release and that successive IP3 additions provoke repetitive bursts of Ca2+ release. Other published interpretations of these observations are discussed.


Luminal Ca2+ increases the sensitivity of Ca2+ stores to inositol 1,4,5-trisphosphate. Ca2+ within intracellular stores has been proposed to act with cytosolic inositol 1,4,5-trisphosphate (InsP3) to cause opening of the integral Ca2+ channel of the InsP3 receptor, leading to mobilization of intracellular Ca2+ stores [FEBS Lett. 263:5-9 (1990)]. We have tested that suggestion in saponin-permeabilized rat hepatocytes by manipulating the Ca2+ content of the stores and then determining their sensitivity to InsP3, while keeping the cytosolic Ca2+ concentration constant. Stores depleted of Ca2+ by incubation with ionomycin were significantly less sensitive to InsP3, an effect thought likely to result from the decrease in luminal free Ca2+ concentration rather than from direct effects of ionomycin on InsP3 binding or Ca2+ permeability. The luminal free Ca2+ concentration of stores loaded in the presence of pyrophosphate appeared to be substantially reduced, and again there was a significant inverse correlation between the estimated free Ca2+ concentration of the stores and their sensitivity to InsP3. By following the kinetics of 45Ca2+ uptake into empty stores in the presence of inositol trisphosphorothioate, a stable InsP3 analogue, we demonstrated that stores respond to inositol trisphosphorothioate only after their luminal free Ca2+ concentration exceeds a critical level. We conclude that InsP3 and luminal Ca2+ together regulate Ca2+ mobilization from intracellular stores, and we discuss some of the implications of this interaction for the complex Ca2+ signals evoked by extracellular stimuli.


Slow voltage-dependent block of sodium channels in crayfish nerve by dihydropyrazole insecticides. Previous current-clamp work has shown that dihydropyrazole insecticides block sodium channels in tonic sensory receptors and in axons depolarized by high K+ external solutions and that hyperpolarization removes the block [Pestic. Sci. 28:389-411 (1990)]. Voltage-clamp studies on internally perfused crayfish giant axons were done to confirm and extend these observations. At -100 mV dihydropyrazoles had little effect on the sodium current, but at more depolarized potentials they blocked it from either face of the membrane. The onset of block following a holding potential change or during wash-in of a dihydropyrazole was very slow, with a time constant of several minutes, and, although block could be removed with a similar time course by hyperpolarization, the effects of the insecticides could not be reversed by prolonged washing. Dihydropyrazoles did not affect delayed rectifier potassium currents in the axon. The voltage-dependent block could be described as a uniform shift of the steady state (slow) sodium inactivation (S infinity) curve in the direction of hyperpolarization, indicative of selective binding to inactivated states of the channel. Using hyperpolarizing prepulses to remove slow inactivation, block of sodium channels by dihydropyrazoles could be measured directly at holding potentials as positive as -50 mV, and it could be demonstrated that block saturated near -70 mV, consistent with a dependence on slow inactivation. The data were fit to a model tha assumes the dihydropyrazole binds to the slow-inactivated state of the channel on a one to one basis. Dissociation constants obtained from this analysis were similar to those obtained from analysis of inhibition of the binding of [benzoyl-2,5-3H]-batrachotoxinin A 20-alpha-benzoate by the same dihydropyrazoles. In axons whose fast or slow inactivation gates had been removed by N-bromoacetamide or trypsin, respectively, dihydropyrazoles still blocked sodium current, indicating that dihydropyrazoles can block the channel as well as enhance the normal slow inactivation process.


Angiotensin II receptor recognized by DuP753 regulates two distinct guanine nucleotide-binding protein signaling pathways. The 7315c cell, derived from a rat anterior pituitary tumor, expresses an angiotensin II (AII) receptor. [3H]AII binds to 7315c membranes specifically and saturably (Kd = 2.1 +/- 0.6 x 10(-6) M, Bmax = 282 +/- 33 fmol/mg of protein). GTP diminished the affinity of the membranes for [3H]AII (Kd = 4.1 +/- 0.4 x 10(-9) M, Bmax = 210 +/- 26 fmol/mg of protein). [3H]AII binding was displaced by AII (Ki = 1.3 +/- 0.6 x 10(-9) M), angiotensin III (AIII) (Ki = 0.9 +/- 0.4 x 10(-9) M), and the nonpeptide AII antagonist DuP753 (Ki = 1.4 +/- 0.6 x 10(-8) M). In contrast, a second nonpeptide AII ligand, PD123177, did not compete for [3H]AII binding sites. In intact cells, AII and AIII stimulated inositol trisphosphate (IP3) production (EC50 = 1.1 +/- 0.6 x 10(-8) M and 1.1 +/- 0.5 x 10(-8) M, respectively); this response to AII was antagonized by DuP753 (Ki = 1.7 +/- 0.3 x 10(-7) M). Pertussis toxin treatment failed to affect the ability of AII to stimulate IP3 production. In a crude membrane preparation, GTP was required for maximal AII-induced IP3 stimulation; guanosine thio-diphosphate abolished the agonist-GTP stimulation of IP3 production, in a concentration-dependent fashion. AII and AIII also inhibited adenylyl cyclase (EC50 = 2.9 +/- 1.1 x 10(-8) M and 6.0 +/- 1.0 x 10(-8) M, respectively). DuP753 antagonized the inhibition by AII of adenylyl cyclase (Ki = 2.8 +/- 0.4 x 10(-8) M). PD123177 failed to antagonize AII-induced cyclase inhibition. Pertussis toxin treatment abolished the AII and AIII inhibition of adenylyl cyclase. GTP was required for AII-induced inhibition of adenylyl cyclase. These data suggest that, in 7315c cells, a single subtype of AII receptor, identified by DuP753, is capable of regulating two different guanine nucleotide-binding protein (G protein) signalling pathways; one G protein, which is insensitive to pertussis toxin, stimulates IP3 production and the other G protein, which is sensitive to pertussis toxin, inhibits adenylyl cyclase.


Carbachol-induced decrease in thyroid cell adenylyl cyclase activity is independent of calcium and phosphodiesterase activation. The mechanism of adenylyl cyclase desensitization by carbachol, an agent that stimulates polyphosphoinositide hydrolysis, was studied in thyroid cells. Incubation of cultured dog thyroid cells with 10 microM carbachol for 2-4 hr reduced the subsequent thyrotropic hormone (TSH) stimulation of adenylyl cyclase activity of membrane preparations by approximately 40%. This inhibition was reversed by atropine, occurred even in a Ca(2+)-free medium containing ethylene glycol bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid, and was not reproduced by the Ca2+ ionophore A23187. The carbachol effect was not prevented by simultaneous incubation of cells with either isobutylmethylxanthine, an inhibitor of phosphodiesterase, or H-7, an inhibitor of protein kinase. Pretreatment of cells with pertussis toxin to inactivate the Gi inhibitory protein also failed to affect the carbachol inhibition. Although carbachol did not reduce the basal or the TSH-stimulated cyclase activities when added to membranes directly during the assay, exposure of cells to carbachol for 2-4 hr resulted in long lasting inhibition of TSH-stimulated cyclase activity (for at least 24 hr); recovery was seen by 48 hr after its removal. Carbachol pretreatment had no effect on 125I-TSH binding to membranes but reduced the cyclase stimulation by not only TSH but also cholera toxin, guanosine 5'-O-(3-thio)triphosphate, and forskolin; it also significantly reduced the cholera toxin-mediated AD[32P]-ribosylation of Gs in membranes. These data indicate that carbachol-induced inhibition of adenylyl cyclase occurs beyond the level of TSH receptor binding and that Gs is a possible site of its action. Thus, in dog thyroid cells, carbachol, via muscarinic receptors, can reduce the adenylyl cyclase activity by a process that does not involve Ca2+ or activation of phosphodiesterase.


Guanylnucleotide specificity for muscarinic receptor inhibitory coupling to cardiac adenylate cyclase. The guanylnucleotide specificity of muscarinic acetylcholine receptor (MR) inhibitory coupling to cardiac adenylate cyclase (AC) was investigated under low MgCl2 (i.e., 0.5 mM) conditions. In purified cardiac sarcolemma, carbachol maximally inhibited AC activity 60% in the presence of GTP. Carbachol-dependent inhibition in the presence of guanosine 5'-O-(3-thiotriphosphate (GTP gamma S) or guanylylimidodiphosphate [Gpp(NH)p] was of lesser magnitude (i.e., 30%) and was evident only during short incubation periods. Of greater interest, carbachol maximally inhibited AC activity in the presence of GDP and guanosine 5'-O-(2-thiodiphosphate (GDP beta S) by 35 and 60%, respectively. Control studies ruled out transphosphorylation of GDP and GDP beta S by nucleoside diphosphate kinase or guanylnucleoside triphosphate contamination as reasons for the inhibitory effects of GDP and GDP beta S. Furthermore, isoproterenol stimulated AC in the presence of GTP, GTP gamma S, and Gpp(NH)p but not in the presence of GDP or GDP beta S. Therefore, GDP and GDP beta S may serve as agonists on MR-activated Gi but not on beta-adrenergic receptor-activated Gs in these membranes. Time course studies revealed that carbachol-dependent inhibition of AC in the presence of either GTP or GDP occurred without a detectable lag period, and this inhibition was rapidly reversed by atropine. In contrast, a 1-2-min lag time was required for carbachol- and GDP beta S-dependent inhibition of AC to occur, and inhibition, once developed, was only partially and slowly reversed by atropine. Preincubation of sarcolemma with carbachol and GDP beta S, in the absence of ATP or under nonphosphorylating conditions, eliminated the lag time for inhibition of AC activity. Although it is unlikely that GDP and GDP beta S have physiological relevance of MR-Gi-AC coupling, these studies provide unique insights into this coupling mechanism in cardiac membranes.


Molecular determinants of mu receptor recognition for the fentanyl class of compounds. We report here a theoretical study of a series of fentanyl analogs with a wide range of affinities and selectivities at the mu receptor, designed to identify and characterize the molecular determinants of mu receptor recognition. In this work, a complete conformational search combining nested rotations and molecular dynamic simulations has been made, leading to identification of accessible conformers for all analogs and to the selection of a candidate bioactive form. In addition, electronic properties have been calculated and examined as possible modulators of recognition at the mu receptor. The results of these studies have led to a distinct pharmacophore for interaction at the mu receptor for this class of compounds, with the piperidine ring in a chair conformation and the N-phenethyl and 4-phenylpropanamide substituents both equatorial. Moreover, four key moieties necessary for optimum receptor recognition and a postulated role for each of them in this recognition have been identified. These are (i) a protonated amine nitrogen, assumed to be involved in an initial electrostatic interaction with a negatively charged site on the receptor; (ii) a polar function capable of hydrogen-bonding with an electrophilic site; (iii) an aromatic ring involved in lipophilic interaction with a similar moiety; and (iv) a second aromatic ring, most probably involved in electron transfer interaction with the receptor. These requirements, taken together, form the basis of our proposed mechanism for mu receptor recognition. Not only is the presence of these components required for recognition, but specific steric relationships between them have been determined, implying the appropriate arrangement for interaction with complementary receptor sites. These steric parameters are pseudobond angles and one torsion angle that determine the relative spatial arrangement of these four moieties. They are the angles theta 1 and theta 3, defining the relative position of the protonated nitrogen and the polar function with each of the two aromatic rings, and the torsion angle eta 1, defining the orientation of the lone pair(s) on the polar proton-accepting function with respect to the lone pair on the piperidine nitrogen. This postulated mechanism of recognition provides a conceptual framework to understand why some compounds do and some do not recognize the mu receptor.


Intracellular metabolism of the antiherpes agent (S)-1-[3-hydroxy-2-(phosphonylmethoxy)propyl]cytosine. (S)-1-[3-Hydroxy-2-(phosphonylmethoxy)propyl]cytosine (HPMPC) is an antiviral phosphonate nucleotide analogue that displays activity against a range of herpesviruses. Anion exchange high performance liquid chromatography analysis of the 60% methanol extract from [14C]HPMPC-treated cells reveals the formation of three major metabolites. Two of these were identified as phosphorylated forms of HPMPC, HPMPC phosphate, and HPMPC diphosphate, by liberation of HPMPC upon acid digestion and coelution with synthetic standards on high performance liquid chromatography. The third metabolite, which is resistant to alkaline phosphatase cleavage but sensitive to phosphodiesterase, is proposed to be an HPMPC phosphate adduct. In herpes simplex virus-1-infected cells the same three metabolites are detected, at concentrations comparable to those in uninfected cells. When HPMPC is removed from the medium, the concentrations of the metabolites in cells decrease slowly, with half-lives of approximately 6, 17, and 48 hr for HPMPC phosphate, HPMPC diphosphate, and the HPMPC phosphate adduct, respectively. HPMPC diphosphate inhibits herpes simplex virus-1 and -2 DNA polymerases with a lower Ki than that for DNA polymerase alpha, and enzyme inhibition is competitive in each case. The formation and the persistence of HPMPC phosphates in cells and the selective inhibition of viral DNA polymerases by HPMPC diphosphate can explain why cells pretreated with HPMPC remain refractory to viral infection even long after HPMPC is removed from the medium.


Differential activation of intracellular effector by two isoforms of human neurokinin-1 receptor. Two isoforms of the human neurokinin-1 receptor were cloned and characterized in heterologous expression systems of mammalian cell culture and Xenopus oocytes. The two isoforms differ only in the length of the encoded polypeptide. The peptide-binding properties of the long form of human neurokinin-1 receptor are consistent with those of the native neurokinin-1 receptor of mammalian tissues, where substance P is the most potent agonist. Peptide agonists elicit an oscillating current in Xenopus oocytes expressing the long form. In contrast, the short form of human neurokinin-1 receptor expressed in COS cells binds substance P with an apparent affinity at least 10-fold lower than that of the long form, and it elicits the electrophysiological response only weakly in Xenopus oocytes. These data suggest that the short form couples to a different effector system. Sequence analysis suggested that the two isoforms may arise from alternative pre-mRNA splicing. These results indicate that multiple forms of the human neurokinin-1 receptor exist and the differential activation of intracellular effector may be involved in generating the complex biological effects of substance P.


Ion dependence of the partially purified mitochondrial dihydropyridine Ca2+ antagonist receptor. The mitochondrial inner membrane contains specific binding sites for dihydropyridine (DHP) Ca2+ antagonists that are associated with an inner mitochondrial membrane anion channel (IMAC) [Mol. Pharmacol. 38:362-369 (1990)]. As in particulate preparations, binding of the DHP (+/-)-[3H]nitrendipine [( 3H]NTR) to partially purified mitochondrial DHP receptors strongly depended on a variety of cations and inorganic as well as organic anions. Monovalent anions saturably stimulated [3H]NTR binding with a potency rank order of I- greater than Br- greater than Cl- greater than F-. The potency rank order for monovalent cations was Cs+ greater than Rb+ greater than Li+ greater than K+ greater than Na+. [3H]NTR binding stimulation potency of the cations strikingly depended on their charge density, with EC50 values being 125 mM for K+, 5 mM for Ca2+, and 41 microM for La3+. This selectivity order clearly differed from one predicted on the basis of a simple surface charge-screening effect of the cations. In general, allosteric ion effects were due to changes in [3H]NTR affinity for the partially purified mitochondrial DHP receptor. SCN- and NO3-, known permeators of the IMAC [J. Biol. Chem. 262:15085-15093 (1987)], stimulated [3H]NTR binding with EC50 values of 26 mM and 96 mM, respectively. The IMAC permeators butylmalonate2- and 1,2,3-benzenetricarboxylate3- were ineffective when given alone but dose-dependently inhibited 500 mM NaCl-stimulated [3H]NTR binding, as did PO4(1.5-) and SO4(2-). Gluconate-, which was reported not to permeate the IMAC, qualitatively behaved as a partial agonist with respect to Cl-. Glucuronate- was without effect on [3H]NTR binding to the partially purified mitochondrial DHP receptor. These results point to the existence of rather large ion-binding domains. The cation-binding site was estimated to have a minimum diameter of 0.67 nm. The anion-binding domain could accommodate either spherical ligands with diameters of up to 0.6 nm or molecules with a flat backbone with dimensions of approximately 0.9 nm x 0.7 nm x 0.3 nm.


Nuclear binding of purified retinoblastoma gene product is determined by cell cycle-regulated phosphorylation. The retinoblastoma tumor suppressor gene product (pRb) is a nuclear protein subject to cell cycle-regulated hyperphosphorylation. I constructed a recombinant vaccinia virus vector that expresses both the underphosphorylated and hyperphosphorylated forms of pRb and purified the recombinant protein by using immunoaffinity chromatography directed toward a synthetic carboxy-terminal epitope. To investigate the hypothesis that hyperphosphorylation of pRb is a means of controlling its growth-regulating activity, I tested purified pRb for the ability to be reincorporated into pRb-deficient nuclei in vitro. The underphosphorylated form of pRb efficiently reassociated with nuclei, but the hyperphosphorylated form remained soluble in this assay. Nuclear binding of pRb was enhanced by phosphatase treatment and reduced by phosphorylation of pRb effected by using a preparation of the cell cycle-regulatory kinase p34cdc2. Mutant-encoded proteins with altered E1A-binding domains failed to bind to nuclei. Pretreatment of target nuclei with nucleases and high-salt extraction did not alter the specificity of binding for underphosphorylated pRb. These observations demonstrate that hyperphosphorylation of pRb can regulate its interaction with nuclei, supporting the hypothesis that hyperphosphorylation controls the growth-regulatory activities of pRb. Further, at least one target of pRb binding appears to be an integral component of the nuclear envelope.


Domain structure of U2 and U4/U6 small nuclear ribonucleoprotein particles from Trypanosoma brucei: identification of trans-spliceosomal specific RNA-protein interactions. Maturation of mRNAs in trypanosomes involves trans splicing of the 5' end of the spliced leader RNA and the exons of polycistronic pre-mRNAs, requiring small nuclear ribonucleoproteins (snRNPs) as cofactors. We have mapped protein-binding sites in the U2 and U4/U6 snRNPs by a combination of RNase H protection analysis, native gel electrophoresis, and CsCl density gradient centrifugation. In the U2 snRNP, protein binding occurs primarily in the 3'-terminal domain; through U2 snRNP reconstitution and chemical modification-interference assays, we have identified discrete positions within stem-loop IV of Trypanosoma brucei U2 RNA that are essential for protein binding; significantly, some of these positions differ from the consensus sequence derived from cis-spliceosomal U2 RNAs. In the U4/U6 snRNP, the major protein-binding region is contained within the 3'-terminal half of U4 RNA. In sum, while the overall domain structure of the U2 and U4/U6 snRNPs is conserved between cis- and trans-splicing systems, our data suggest that there are also trans-spliceosomal specific determinants of RNA-protein binding.


Transcriptional transactivation functions localized to the glucocorticoid receptor N terminus are necessary for steroid induction of lymphocyte apoptosis. Genetic studies have suggested that transcriptional regulation of specific target genes (by either induction or repression) is the molecular basis of glucocorticoid-mediated lymphocyte apoptosis. To examine the role of transcriptional regulation more directly, we developed a complementation assay utilizing stable transfection of wild-type (wt) and mutant (nti) glucocorticoid receptor (GR) cDNA constructs into a GR-deficient S49 murine cell line (7r). Our data confirm that the level of functional GR is rate limiting for S49 apoptosis and moreover that the GR amino terminus (N terminus), which as been deleted from the nti GR, is absolutely required for complementation in this system. Surprisingly, we found that at physiological levels of receptor, expression of the nti GR in cells containing wt GR results in enhanced dexamethasone sensitivity rather than a dominant negative phenotype. One interpretation of these data is that DNA binding by wt-nti heterodimers may be functionally similar to that of wt-wt homodimers, indicating that GRE occupancy by at least one transactivation domain may be sufficient to induce the hormonal response. To determine whether acidic activating sequences such as those localized to the GR N terminus are important in the induction of lymphocyte apoptosis, we tested the activity of a chimeric receptor in which we replaced the entire GR N terminus with sequences from the herpes simplex virus VP16 protein. Our results demonstrate that 7r cells expressing VP-GR fusions are indeed steroid sensitive, strongly supporting the idea that S49 apoptosis is dependent on transcriptional regulation of specific genes which respond to acidic activating domains, implying that induction, rather than repression, may be the critical initiating event.


Connections between RNA splicing and DNA intron mobility in yeast mitochondria: RNA maturase and DNA endonuclease switching experiments. The intron-encoded proteins bI4 RNA maturase and aI4 DNA endonuclease can be faithfully expressed in yeast cytoplasm from engineered forms of their mitochondrial coding sequences. In this work we studied the relationships between these two activities associated with two homologous intron-encoded proteins: the bI4 RNA maturase encoded in the fourth intron of the cytochrome b gene and the aI4 DNA endonuclease (I-SceII) encoded in the fourth intron of the gene coding for the subunit I of cytochrome oxidase. Taking advantage of both the high recombinogenic properties of yeast and the similarities between the two genes, we constructed in vivo a family of hybrid genes carrying parts of both RNA maturase and DNA endonuclease coding sequences. The presence of a sequence coding for a mitochondrial targeting peptide upstream from these hybrid genes allowed us to study the properties of their translation products within the mitochondria in vivo. We thus could analyze the ability of the recombinant proteins to complement RNA maturase deficiencies in different strains. Many combinations of the two parental intronic sequences were found in the recombinants. Their structural and functional analysis revealed the following features. (i) The N-terminal half of the bI4 RNA maturase could be replaced in total by its equivalent from the aI4 DNA endonuclease without affecting the RNA maturase activity. In contrast, replacing the C-terminal half of the bI4 RNA maturase with its equivalent from the aI4 DNA endonuclease led to a very weak RNA maturase activity, indicating that this region is more differentiated and linked to the maturase activity. (ii) None of the hybrid proteins carrying an RNA maturase activity kept the DNA endonuclease activity, suggesting that the latter requires the integrity of the aI4 protein. These observations are interesting because the aI4 DNA endonuclease is known to promote the propagation, at the DNA level, of the aI4 intron, whereas the bI4 RNA maturase, which is required for the splicing of its coding intron, also controls the splicing process of the aI4 intron. We propose a scenario for the evolution of these intronic proteins that relies on a switch from DNA endonuclease to RNA maturase activity.


In vitro phosphorylation of the erythropoietin receptor and an associated protein, pp130. The cytoplasmic domain of the cloned erythropoietin (EPO) receptor (EPOR) contains no protein kinase motif, yet addition of EPO to EPO-responsive cells causes an increase in protein-tyrosine phosphorylation. Here we show that addition of EPO or interleukin-3 (IL-3) to an IL-3-dependent cell line expressing the wild-type EPOR causes a small fraction (less than 5%) of total cellular EPOR to shift in gel mobility from 66 to 72 kDa, due at least in part to phosphorylation. Using biotinylated EPO as an affinity reagent, we show that the 72-kDa species is greatly enriched on the cell surface. To demonstrate that a protein kinase activity associates with cell surface EPOR, cells were incubated with biotinylated EPO and then cross-linked with a thiol-cleavable chemical cross-linker. The avidin-agarose-selected complexes were incubated with [gamma-32P]ATP. After in vitro phosphorylation and denaturation without reducing agent, both antiphosphotyrosine and anti-EPOR antibodies immunoprecipitated labeled 72-kDa EPOR and an unidentified 130-kDa phosphoprotein (pp130), indicating that a protein kinase is associated with cell surface EPOR and that a fraction of the EPOR was phosphorylated on tyrosine residues either in the cells or during the cell-free phosphorylation reaction. Under reducing conditions, the 72-kDa phosphorylated EPOR but not pp130 was immunoprecipitated with an anti-EPOR antibody, suggesting that the pp130 is bound to the EPOR by the thiol-cleavable chemical cross-linker. Previously, we showed that deletion of the 42 carboxy-terminal amino acids of the EPOR allows cells to grow in 1/10 the normal EPO concentration, without affecting receptor number or affinity. Two carboxy-terminal truncated EPO receptors that are hyperresponsive to EPO were poorly phosphorylated during the in vitro reaction, suggesting that the carboxy-terminal region of the EPOR contains a site for phosphorylation or a site for interaction with a protein kinase. Our data suggests that phosphorylation or interaction with a protein kinase in the carboxy-terminal region may down-modulate the proliferative action of the EPOR.


Three novel functional variants of human U5 small nuclear RNA. We have identified and characterized three new variants of U5 small nuclear RNA (snRNA) from HeLa cells, called U5D, U5E, and U5F. Each variant has a 2,2,7-trimethylguanosine cap and is packaged into an Sm-precipitable small nuclear ribonucleoprotein (snRNP) particle. All retain the evolutionarily invariant 9-base loop at the top of stem 1; however, numerous base changes relative to the abundant forms of U5 snRNA are present in other regions of the RNAs, including a loop that is part of the yeast U5 minimal domain required for viability and has been shown to bind a protein in HeLa extracts. U5E and U5F each constitute 7% of the total U5 population in HeLa cells and are slightly longer than the previously characterized human U5 (A, B, and C) species. U5D, which composes 5% of HeLa cell U5 snRNAs, is present in two forms: a full-length species, U5DL, and a shorter species, U5DS, which is truncated by 15 nucleotides at its 3' end and therefore resembles the short form of U5 (snR7S) in Saccharomyces cerevisiae. We have established conditions that allow specific detection of the individual U5 variants by either Northern blotting (RNA blotting) or primer extension; likewise, U5E and U5F can be specifically and completely degraded in splicing extracts by oligonucleotide-directed RNase H cleavage. All variant U5 snRNAs are assembled into functional particles, as indicated by their immunoprecipitability with anti-(U5) RNP antibodies, their incorporation into the U4/U5/U6 tri-snRNP complex, and their presence in affinity-purified spliceosomes. The higher abundance of these U5 variants in 293 cells compared with that in HeLa cells suggests possible roles in alternative splicing.


Linked spontaneous CG----TA mutations at CpG sites in the gene for protein kinase regulatory subunit. CG----TA transitions at CpG sequences account for many human point mutations and are thought to result from hydrolytic deamination of 5-methylcytosine residues in these sites. The gene for regulatory subunit of murine cyclic AMP-dependent protein kinase has two closely linked CpG sites, one of which is a strong hotspot for spontaneous CG----TA mutations leading to cyclic AMP resistance in S49 mouse lymphoma cells. About 5% of mutants with a spontaneous mutation at this CpG site had also acquired a second CG----TA mutation at the nearby CpG site. The two mutations were always at first positions of the Arg codons in which they occurred, and they were always together in a single regulatory subunit allele. Their linked appearance could be attributed to neither the selection conditions nor the preexistence of one mutation in the target cells. The high frequency of these double mutants suggests that their lesions result not from hydrolytic deamination but rather from an endogenous enzymatic mechanism.


Characterization of a fusion cDNA (RARA/myl) transcribed from the t(15;17) translocation breakpoint in acute promyelocytic leukemia. A nonrandom chromosomal translocation breakpoint, t(15;17)(q22;q21), is found in almost all patients with acute promyelocytic leukemia (APL). Most of these breakpoints occur within the second intron of the retinoic acid receptor-alpha (RARA) gene. We screened a cDNA library of APL and have identified and sequenced a cDNA transcribed from the t(15;17) translocation breakpoint. The 5' end of cDNA p1715 consists of 503 bp of the RARA exon II sequence. A 1.76-kb cDNA without homology to any known gene available in GenBank was found truncated downstream. This cDNA sequence was assigned to chromosome 15 by dot blot hybridization of the flow cytometry-sorted chromosomes. We designate this fusion cDNA RARA/myl, which is different from myl/RARA reported by de The et al. (H. de The, C. Chomienne, M. Lanotte, L. Degos, and A. Dejean, Nature (London) 347:558-561, 1990). This result demonstrates that the two different types of hybrid mRNA can be transcribed from this breakpoint. We screened a non-APL cDNA library and identified a 2.8-kb myl cDNA. This cDNA is able to encode a polypeptide with a molecular weight of 78,450. Alternative splicing of the myl gene which resulted in myl proteins with different C terminals was found. Southern blot analysis of the genomic DNA isolated from 17 APL patients by using the myl DNA probe demonstrated that the myl gene in 12 samples was rearranged. Northern (RNA) blot analysis of RARA gene expression in two APL RNA samples showed abnormal mRNA species of 4.2 and 3.2 kb in one patient and of 4.8 and 3.8 kb in another patient; these were in addition to the normal mRNA species of 3.7 and 2.7-kb. The myl DNA probe detected a 2.6-kb abnormal mRNA in addition to the normal mRNA species of 3.2, 4.2, and 5.5 kb. Using the polymerase chain reaction, we demonstrated that both RARA/myl and myl/RARA were coexpressed in samples from three different APL patients. From this study, we conclude that the t(15;17) translocation breakpoint results in the transcription of two different fusion transcripts which are expected to be translated into fusion proteins.


Inhibitory effect of myristylation on transrepression by FBR (Gag-Fos) protein. The myristylated v-fos product, FBR murine sarcoma virus (Gag-Fos) protein, exhibits a lower level of transrepression of the serum response element (SRE) than does c-fos protein (Fos). Mutation of the N-terminal myristylation site in FBR protein restored SRE transrepression. Replacement of N-terminal viral Gag sequences with the Fos N terminus also restored this activity, providing additional evidence that myristylation inhibits transrepression by FBR protein. However, the myristylated Gag domain did not inhibit SRE transrepression when fused to Fos, indicating that myristylation of a fos protein is not by itself sufficient to prevent SRE transrepression and that C-terminal mutation is necessary to inhibit transrepression by N myristylation. Comparison of transfection results with Fos C-terminal deletion mutants and the Fos/FBR chimeric mutant revealed that the FBR C terminus retained the potential for transrepression despite deletion of the normal Fos C terminus, whereas similar Fos deletion mutants did not. These results indicate that both N- and C-terminal mutations are required to inhibit transrepression by FBR protein and that multiple structural mutations accompanied by posttranslational protein modification alter gene regulation by FBR protein.


Interindividual variability of central delay changes in the soleus H reflex pathway. Central delay (CD) changes in the soleus H reflex pathway, as demonstrated by variations in the time interval between afferent (P1) and efferent (P2) neurographic volleys underlying the reflex response, were assessed in a group of normal subjects, both during the steady state and after homosynaptic spatial summation of afferent impulses. The maximal range of CD changes, regardless of whether "spontaneous" or provoked, showed significant interindividual differences whose size was positively related to the Hmax/Mmax ratio, provided that the extension of the subliminal fringe was suitably normalized. Comparatively similar variations in amplitude of the reflex motoneuronal discharge under different experimental conditions can be associated with different CD changes. Indeed, "spontaneous" CD fluctuations occurring during the steady state were consistently greater than CD reductions provoked by spatial summation, the gap size being negatively related to the Hmax/Mmax ratio.


Invited review: autonomic dysfunction in peripheral nerve disease. The autonomic nervous system is affected in most peripheral neuropathies, but only in a small number of conditions, such as diabetes, amyloidosis, Guillain-Barré syndrome, porphyria, and familiar dysautonomia, is autonomic dysfunction of clinical importance. The pathological changes in the peripheral autonomic nervous system are similar to those in the peripheral somatic nerves. Autonomic disturbances are most likely to occur when there is acute demyelination or damage to small myelinated and unmyelinated fibers. Autonomic investigations should include tests of both sympathetic and parasympathetic function. Treatment consists of management of the underlying cause of peripheral neuropathy, physical and pharmacological measures.


Streptozocin-doxorubicin, streptozocin-fluorouracil or chlorozotocin in the treatment of advanced islet-cell carcinoma. The combination of streptozocin and fluorouracil has become the standard therapy for advanced islet-cell carcinoma. However, doxorubicin has also been shown to be active against this type of tumor, as has chlorozotocin, a drug that is structurally similar to streptozocin but less frequently causes vomiting. In this multicenter trial, we randomly assigned 105 patients with advanced islet-cell carcinoma to receive one of three treatment regimens: streptozocin plus fluorouracil, streptozocin plus doxorubicin, or chlorozotocin alone. The 31 patients in whom the disease did not respond to treatment were crossed over to chlorozotocin alone or to one of the combination regimens. Streptozocin plus doxorubicin was superior to streptozocin plus fluorouracil in terms of the rate of tumor regression, measured objectively (69 percent vs. 45 percent, P = 0.05), and the length of time to tumor progression (median, 20 vs. 6.9 months; P = 0.001). Streptozocin plus doxorubicin also had a significant advantage in terms of survival (median, 2.2 vs. 1.4 years; P = 0.004) that was accentuated when we considered long-term survival (greater than 2 years). Chlorozotocin alone produced a 30 percent regression rate, with the length of time to tumor progression and the survival time equivalent to those observed with streptozocin plus fluorouracil. Crossover therapy after the failure of either chlorozotocin alone or one of the combination regimens produced an overall response rate of only 17 percent, and the responses were transient. Toxic reactions to all regimens included vomiting, which was least severe with chlorozotocin; hematologic depression; and, with long-term therapy, renal insufficiency. The combination of streptozocin and doxorubicin is superior to the current standard regimen of streptozocin plus fluorouracil in the treatment of advanced islet-cell carcinoma. Chlorozotocin alone is similar in efficacy to streptozocin plus fluorouracil, but it produces fewer gastrointestinal side effects than the regimens containing streptozocin. It therefore merits study as a constituent of combination drug regimens.


Effects of concomitant cisplatin and radiotherapy on inoperable non-small-cell lung cancer. Cisplatin (cis-diamminedichloroplatinum) has been reported to enhance the cell-killing effect of radiation, an effect whose intensity varies with the schedule of administration. We randomly assigned 331 patients with nonmetastatic inoperable non-small-cell lung cancer to one of three treatments: radiotherapy for two weeks (3 Gy given 10 times, in five fractions a week), followed by a three-week rest period and then radiotherapy for two more weeks (2.5 Gy given 10 times, five fractions a week); radiotherapy on the same schedule, combined with 30 mg of cisplatin per square meter of body-surface area, given on the first day of each treatment week; or radiotherapy on the same schedule, combined with 6 mg of cisplatin per square meter, given daily before radiotherapy. Survival was significantly improved in the radiotherapy-daily-cisplatin group as compared with the radiotherapy group (P = 0.009): survival in the radiotherapy-daily-cisplatin group was 54 percent at one year, 26 percent at two years, and 16 percent at three years, as compared with 46 percent, 13 percent, and 2 percent, respectively, in the radiotherapy group. Survival in the radiotherapy-weekly-cisplatin group was intermediate (44 percent, 19 percent, and 13 percent) and not significantly different from survival in either of the other two groups. The survival benefit of daily combined treatment was due to improved control of local disease (P = 0.003). Survival without local recurrence was 59 percent at one year and 31 percent at two years in the radiotherapy-daily-cisplatin group; 42 percent and 30 percent, respectively, in the radiotherapy-weekly-cisplatin group; and 41 percent and 19 percent, respectively, in the radiotherapy group. Cisplatin induced nausea and vomiting in 86 percent of the patients given it weekly and in 78 percent of those given it daily; these effects were severe in 26 percent and 28 percent, respectively. Cisplatin, given daily in combination with the radiotherapy described here to patients with nonmetastatic but inoperable non-small-cell lung cancer, improved rates of survival and control of local disease at the price of substantial side effects.