Determination of the

We report the first measurement of the parity-violating elastic electron scattering asymmetry on ^{27}Al. The ^{27}Al elastic asymmetry is A_{PV}=2.16±0.11(stat)±0.16(syst) ppm, and was measured at ⟨Q^{2}⟩=0.02357±0.00010 GeV^{2}, ⟨θ_{lab}⟩=7.61°±0.02°, and ⟨E_{lab}⟩=1.157 GeV with the Q_{weak} apparatus at Jefferson Lab. Predictions using a simple Born approximation as well as more sophisticated distorted-wave calculations are in good agreement with this result. From this asymmetry the ^{27}Al neutron radius R_{n}=2.89±0.12 fm was determined using a many-models correlation technique. The corresponding neutron skin thickness R_{n}-R_{p}=-0.04±0.12 fm is small, as expected for a light nucleus with a neutron excess of only 1. This result thus serves as a successful benchmark for electroweak determinations of neutron radii on heavier nuclei. A tree-level approach was used to extract the ^{27}Al weak radius R_{w}=3.00±0.15 fm, and the weak skin thickness R_{wk}-R_{ch}=-0.04±0.15 fm. The weak form factor at this Q^{2} is F_{wk}=0.39±0.04.

Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering.

A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of θ_{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B_{n}=-5.194±0.067(stat)±0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (θ_{lab}→0) where they should be most reliable.

First determination of the weak charge of the proton.

The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 µA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.

Measurement of the parity-violating asymmetry in inclusive electroproduction of π- near the Δ0 resonance.

The parity-violating (PV) asymmetry of inclusive π- production in electron scattering from a liquid deuterium target was measured at backward angles. The measurement was conducted as a part of the G0 experiment, at a beam energy of 360 MeV. The physics process dominating pion production for these kinematics is quasifree photoproduction off the neutron via the Δ0 resonance. In the context of heavy-baryon chiral perturbation theory, this asymmetry is related to a low-energy constant d(Δ)- that characterizes the parity-violating γNΔ coupling. Zhu et al. calculated d(Δ)- in a model benchmarked by the large asymmetries seen in hyperon weak radiative decays, and predicted potentially large asymmetries for this process, ranging from A(γ)-=-5.2 to +5.2 ppm. The measurement performed in this work leads to A(γ)-=-0.36±1.06±0.37±0.03 ppm (where sources of statistical, systematic and theoretical uncertainties are included), which would disfavor enchancements considered by Zhu et al. proportional to V(ud)/V(us). The measurement is part of a program of inelastic scattering measurements that were conducted by the G0 experiment, seeking to determine the N-Δ axial transition form factors using PV electron scattering.

Transverse beam spin asymmetries at backward angles in elastic electron-proton and quasielastic electron-deuteron scattering.

We have measured the beam-normal single-spin asymmetries in elastic scattering of transversely polarized electrons from the proton, and performed the first measurement in quasielastic scattering on the deuteron, at backward angles (lab scattering angle of 108°) for Q² = 0.22 GeV²/c² and 0.63 GeV²/c² at beam energies of 362 and 687 MeV, respectively. The asymmetry arises due to the imaginary part of the interference of the two-photon exchange amplitude with that of single-photon exchange. Results for the proton are consistent with a model calculation which includes inelastic intermediate hadronic (πN) states. An estimate of the beam-normal single-spin asymmetry for the scattering from the neutron is made using a quasistatic deuterium approximation, and is also in agreement with theory.

Strange quark contributions to parity-violating asymmetries in the backward angle G0 electron scattering experiment.

We have measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2=0.22 and 0.63 GeV2. They are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of approximately < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial-vector current at these four-momentum transfers.

Subtle cerebellar phenotype in mice homozygous for a targeted deletion of the En-2 homeobox.

The two mouse genes, En-1 and En-2, that are homologs of the Drosophila segmentation gene engrailed, show overlapping spatially restricted patterns of expression in the neural tube during embryogenesis, suggestive of a role in regional specification. Mice homozygous for a targeted mutation that deletes the homeobox were viable and showed no obvious defects in embryonic development. This may be due to functional redundancy of En-2 and the related En-1 gene product during embryogenesis. Consistent with this hypothesis, the mutant mice showed abnormal foliation in the adult cerebellum, where En-2, and not En-1, is normally expressed.

Test of intron predictions reveals novel splice sites, alternatively spliced mRNAs and new introns in meiotically regulated genes of yeast.

Correct identification of all introns is necessary to discern the protein-coding potential of a eukaryotic genome. The existence of most of the spliceosomal introns predicted in the genome of Saccharomyces cerevisiae remains unsupported by molecular evidence. We tested the intron predictions for 87 introns predicted to be present in non-ribosomal protein genes, more than a third of all known or suspected introns in the yeast genome. Evidence supporting 61 of these predictions was obtained, 20 predicted intron sequences were not spliced and six predictions identified an intron-containing region but failed to specify the correct splice sites, yielding a successful prediction rate of <80%. Alternative splicing has not been previously described for this organism, and we identified two genes (YKL186C/ MTR2 and YML034W) which encode alternatively spliced mRNAs; YKL186C/ MTR2 produces at least five different spliced mRNAs. One gene (YGR225W/ SPO70 ) has an intron whose removal is activated during meiosis under control of the MER1 gene. We found eight new introns, suggesting that numerous introns still remain to be discovered. The results show that correct prediction of introns remains a significant barrier to understanding the structure, function and coding capacity of eukaryotic genomes, even in a supposedly simple system like yeast.

The effect of calmodulin inhibitors with bleomycin on the treatment of patients with high grade gliomas.

Glioblastoma multiforme is a fatal malignancy of the central nervous system, demanding new methods of treatment. The combination of a calmodulin antagonist with bleomycin has shown synergistic activity in several preclinical models and has been evaluated in a Phase I clinical trial. Since phenothiazines reach high concentrations in the central nervous system, and bleomycin has been reported to have antitumoral activity as well, we studied this combination in a Phase II clinical trial. In addition, we purified calmodulin from normal brain and malignant gliomas to determine its biochemical and pharmacological characteristics. Seventeen patients were entered onto this study and all were evaluable. There were no partial or complete responses. There was one case of fatal pulmonary toxicity in a patient showing an objective tumor response. Otherwise, the treatment was well tolerated. Calmodulin purified from the normal brain and gliomas of patients undergoing resection was identical to each other and to calmodulin prepared from rat cerebrum and glioma. These characteristics included elution from a TSK phenyl high pressure liquid chromatography column, migration on 16% sodium dodecyl sulfate gels, amino acid composition, and inhibition by drugs. Therefore, the failure of this combination therapy was not due to a difference in human glioma calmodulin as compared to previously reported studies with calmodulin from murine sources.

A randomized phase I/II study of continuous versus intermittent intravenous interferon gamma in patients with metastatic melanoma.

Thirty patients with documented metastatic melanoma were randomly assigned to receive recombinant DNA-produced gamma-interferon (specific activity approximately, 20 MU/mg) intravenously (IV) over either two or 24 hours at dosages of 3, 30, 300, 1,000, or 3,000 micrograms/m2. Objective toxicity resembled that of alpha-interferon and included fever, chills, myalgias, headache, and fatigue. Neutropenia, elevations in liver enzymes, tachyarrhythmias, and CNS changes also were noted. Dose-limiting toxicity included neutropenia, liver enzyme abnormality, constitutional symptoms, and a change in mental status. The incidence of toxicity was qualitatively similar in both two- and 24-hour treatment arms, but was quantitatively more severe in the 24-hour continuous infusion arm. Maximum tolerated dose was 1,000 micrograms/m2 in both schedules. Pharmacokinetic studies showed a half-life of six to nine hours. One patient had a complete response after two cycles of therapy and an additional patient entered partial remission after three cycles. Recombinant gamma-interferon (rIRN-gamma) is tolerated at dosages of 1,000 micrograms/m2 administered daily either by two or 24 hour infusion for 14 days in patients with metastatic melanoma. The responses documented in this early trial warrant further evaluation for the treatment of metastatic melanoma.

Pharmacokinetic and phase I trial of intraperitoneal carboplatin and cyclosporine in refractory ovarian cancer patients.

PURPOSE: The feasibility and pharmacokinetics of cyclosporine (CsA) delivered intraperitoneally (IP) have not been previously explored. We performed a pharmacokinetic study of IP CsA followed by a phase I dose-escalation trial of the combination of IP CsA and carboplatin in refractory ovarian cancer patients. PATIENTS AND METHODS: A pilot study was performed of three patients who received 1, 10, and 20 mg/kg IP CsA alone. Subsequently, a phase I trial of 35 patients was performed between April 1990 and April 1993. Whole-blood and IP fluid CsA concentrations were measured at serial time points. The highest dose delivered IP was 34.6 mg CsA/kg in combination with carboplatin (250 mg/m2 or 300 mg/m2, depending on creatinine clearance), which was not dose-escalated. The area under the concentration-time curve (AUC) for CsA and half-life (T1/2) were calculated. Objective and serologic responses were noted, and toxicity was graded using the National Cancer Institute common toxicity criteria. RESULTS: The feasibility of delivering IP CsA alone was established. We observed a 1,000:1 ratio between IP fluid and blood concentrations at 20 mg CsA/kg. Pharmacokinetic analysis confirmed that at 20 mg CsA/kg, there was an IP fluid-to-blood AUC ratio of 600:1 in favor of peritoneal exposure. At the highest dose delivered, 34.6 mg CsA/kg, the mean IP CsA levels of 1,110 micrograms/ mL were tolerated moderately well and the IP fluid-to-blood ratio of 1,000:1 was maintained. Blood and IP CsA concentrations were analyzed in the presence and absence of IP carboplatin. At 20 mg CsA/kg, there was no difference in either mean blood CsA levels (0.9 microgram/ mL) or mean IP CsA concentrations (1,000 micrograms/mL) obtained in the absence or presence of carboplatin. The most common toxicity in the phase I study was anemia, seen in 66% of patients. Common toxicities at the maximum CsA dose delivered (34.6 mg/kg) were anemia, leukopenia, thrombocytopenia, and hypertension. In this trial, three objective responses (two complete and one partial) were observed for a duration of 3 to 11 months. Control of platinum-resistant ascites was an important feature, noted in five of eight patients. CONCLUSION: We have established the feasibility of delivering IP CsA up to doses of 34.6 mg/kg in conjunction with carboplatin, and the sustaining of IP fluid to blood ratios of 1,000:1. The IP administration of CsA resulted in a favorable ratio of exposure for the peritoneal cavity compared with systemic exposure, indicating a therapeutic advantage of this approach with a significant decrease in systemic toxicity. We recommend that 34.6 mg/ kg of IP CsA be tested as a phase II dose in combination with carboplatin in refractory ovarian cancer patients. This report provides the groundwork for future studies using IP CsA, both as a chemomodulator of platinum and of multidrug resistance.

In vivo biological response to recombinant interferon-gamma during a phase I dose-response trial in patients with metastatic melanoma.

Interferon-gamma (IFN gamma), as produced by recombinant DNA technology, has shown a wide range of immunomodulatory activity in vitro and in vivo. Clinical studies have attempted to establish a dose-response relationship to define optimal dosage ranges for induction of effector cell function and host response in patients with cancer. We conducted a randomized trial to test the in vivo biologic activity of five daily dosages ranging from 3 to 3,000 micrograms/m2, administered by daily 2-hour bolus injection or by continuous infusion for 14 days. We demonstrate comparable immunobiologic effects of recombinant IFN gamma (rIFN gamma; Biogen, Inc, Cambridge, MA) administered by these two schedules at the various dosages tested, and have defined a relationship of dose to biologic response over this 3-log10 dose range. Oligo 2'5' adenylate synthetase (2'5'As) induction, natural-killer (NK) cell activity, and T-cell subset distribution (heightened T helper/suppressor ratio) showed the most consistent treatment-associated changes and the greatest immunobiologic effects at dosages of 300 to 1,000 micrograms/m2. Mononuclear cell DR and DQ antigen expression showed no consistent dose-related treatment effect. The relevance of the phenotypic, functional, and enzymologic effects observed in this trial to any clinical antitumor effects of IFN gamma in cancer therapy must now be established.

The influence of drug interval on the effect of methotrexate and fluorouracil in the treatment of advanced colorectal cancer.

The importance of the interval between methotrexate (MTX) and fluorouracil (5-FU) was studied in 168 patients with previously untreated, measurable, advanced colorectal cancer. They were randomized to receive MTX 200 mg/m2, followed by 5-FU 600 mg/m2 either 24 hours (arm A) or 1 hour (arm B) after MTX. All patients received leucovorin (LV) 24 hours after MTX, 10 mg/m2 orally every 6 hours for six doses. The regimen was repeated every 2 weeks, with 5-FU escalation as tolerated. Arm A was significantly better than arm B with respect to overall response rate (29% v 14.5%, P = .026), time to progression (TTP; median, 9.9 months v 5.9 months, P = .009), and survival (median, 15.3 months v 11.4 months, P = .003). Significant differences between arms were not found in response rate, median TTP, or median survival for the subgroup of patients with rectal primaries who comprised 20% of the patients in each arm. Significant factors prognostic for survival were performance status and number of metastases, as well as treatment. Age did not influence survival. Toxicity was similar in both arms and was primarily gastrointestinal. More mucositis was seen in arm A. There were four toxic deaths secondary to neutropenia and infection (one from arm A and three from arm B) and three other deaths (two from arm A and one from arm B) that were possibly drug-related. The combination of MTX with LV rescue and 5-FU is an active regimen in advanced colorectal cancer; its efficacy is increased in colon, but not rectal cancer, when the interval between MTX and 5-FU is long (24 hours) rather than short (1 hour).

Coronary vascular responsiveness to adenosine is impaired additively by blockade of nitric oxide synthesis and a sulfonylurea.

OBJECTIVES: We sought to define effects of glibenclamide, a sulfonylurea known to block ATP-dependent potassium (KATP) channels, and Nomega-nitro-L-arginine methyl ester (L-NAME), an L-arginine analog known to block nitric oxide (NO) synthesis, on coronary vascular responsiveness to adenosine. BACKGROUND: The role of adenosine in coronary flow regulation becomes increasingly important when KATP channel function or NO synthesis is impaired. Both variables are potentially altered in patients with coronary artery disease taking a sulfonylurea. METHODS: Dose-response curves relating coronary conductance to plasma adenosine concentration were obtained by using intracoronary infusions of adenosine (10 to 1,000 microg/min) in chronically instrumented dogs. RESULTS: ED50, the plasma concentration of adenosine needed to produce 50% of the maximal increase in conductance under baseline conditions, increased threefold after either 1 or 10 mg/kg of L-NAME. ED50 also increased in response to glibenclamide in a dose-related fashion (5.7-fold increase per 1 mg/kg body weight of glibenclamide). Effects of combined blockade of KATP channels and NO synthesis were additive, with increases in ED50 as high as 15-fold. Both L-NAME and glibenclamide increased systemic pressure and reduced coronary conductance, confirming the roles of NO and KATP channels in regulating coronary and systemic vascular tone under rest conditions as well as during stress. CONCLUSIONS: Coronary vascular responsiveness to adenosine is blunted in vivo by both L-NAME and glibenclamide. Effects of the sulfonylurea and blockade of NO synthesis are additive and can limit coronary vasodilation as well as other responses involving KATP channels and NO.

Modulation of platinum sensitivity and resistance by cyclosporin A in refractory ovarian and fallopian tube cancer patients: a phase II study.

Our objective was to assess the activity of cyclosporin A (CsA) used as a chemomodulator of carboplatin in refractory ovarian and fallopian tube cancer patients. Fifty-one patients (47 epithelial ovarian, 1 ovarian mixed mesodermal tumor, and 3 fallopian tube carcinomas) were enrolled in a prospective Phase II trial of CsA and carboplatin. CsA was infused as a loading dose of 10 mg/kg over 5 h, followed by carboplatin infused over 30 min at an AUC of 6 mg/ml x min, then a 24-h continuous infusion of 11.6 mg/kg CsA. The patients received this protocol as second- to sixth-line therapy and had received between 1 and 3 prior platinum-based regimens. Eight patients received more than six cycles every 28 days, 34 patients received three to six cycles; and 9 patients received only one or two cycles. Thirty-eight patients were evaluable for objective response, and in an additional nine patients, CA-125 was the only marker of response. Four patients had no marker of disease. Of evaluable patients, 74% were platinum resistant. There were nine objective responses (one complete and eight partial responses) for an overall response rate in evaluable patients of 24%, with a median duration of response of 7 months (range, 3-38+ months). No responses were seen in patients who had received only one or two cycles of therapy. Among the strictly defined platinum-resistant patients, there was an overall 14% response rate, including one partial response seen after five prior regimens of chemotherapy including paclitaxel, and one ongoing complete response for 38+ months. Among the rest of the patients (those who were potentially platinum sensitive), there was an overall 50+ response rate; four of five responses were seen in patients with a platinum-free interval of <24 months, with only one response seen in a patient with a platinum-free interval of >24 months. Of evaluable patients, 34% had stable disease for a duration of 3-19 months. The most common grade 3 or 4 toxicity, thrombocytopenia, was seen in 22% of the patients. Hypertension, which responded to medications, was seen in 18% of the patients during the CsA infusion. We concluded that this CsA/carboplatin regimen is active in potentially platinum-sensitive patients and compares well with the expected response rate of 30% in patients with a platinum-free interval <24 months who are retreated with platinum. Moreover, this regimen had modest but real activity in platinum-resistant patients.

Phase I trial of intravenous carboplatin and cyclosporin A in refractory gynecologic cancer patients.

Our objective was to determine the maximum tolerated dose of cyclosporin A (CsA) delivered as a loading dose (LD) and continuous i.v. infusion (CI) in combination with carboplatin in patients with refractory gynecologic cancers. Twenty-nine heavily pretreated patients (25 ovarian epithelial, 2 cervical, and 2 endometrial carcinomas) received 113 cycles of CsA and carboplatin from September 1989 to September 1991. Twenty-four of these 29 carcinomas were strictly defined to be platinum resistant. CsA was administered as a LD escalated from 6 to 10 mg/kg followed by a 24-h CI from 2.5 to 14.5 mg/kg/day. Carboplatin was targeted to an area under the time versus concentration curve (AUC) of 6 mg/ml x min and was not dose escalated. Whole-blood CsA concentrations (fluorescence polarization immunoassay) at the maximum tolerated dose (10 mg/kg LD, 14.5 mg/kg/day CI) ranged from 2.4 to 3.0 microgram/ml over 12 h. Estimated median carboplatin AUC, based on calculated carboplatin clearance, was 7.9 mg/ml x min. The dose-limiting toxicity of the combination of CsA and carboplatin was grade 4 thrombocytopenia. Grade 3 or 4 thrombocytopenia occurred in 35% of the patients, which could be explained by the effects of carboplatin (AUC of 6 mg/ml x min) alone. Overall, neutropenia occurred in 24% of the patients and anemia in 17% of the patients. Grade 3 or 4 nausea or vomiting was noted in 10 and 14% of the patients, respectively. Grade 3 hypertension during CsA administration occurred in 14% of the patients. No grade 3 or 4 nephrotoxicity was seen in this trial. Three objective responses were noted: one complete response (11 months) and one partial response (5 months), both in potentially platinum-sensitive patients with platinum-free intervals of only 9 months each. One platinum-resistant patient had a partial response for 21 months. Five additional patients experienced >75% reduction of CA-125 or a return to a normal CA-125 titer. We concluded that whole-blood CsA concentrations of >3.0 microgram/ml (as seen when CsA is used as a modulator of multidrug resistance) were not achievable in this combination with carboplatin in this population of heavily pretreated gynecologic cancer patients. However, because CsA is used in this trial as a chemosensitizer in platinum-sensitive tumors and as a chemomodulator of platinum resistance, we targeted a CsA concentration of >1.0 microgram/ml, which was achieved. The CsA dose recommended for a Phase II trial of this combination is 10 mg/kg LD and 11.6 mg/kg/day CI, which results in blood CsA concentrations ranging from 1.2 to 1.3 microgram/ml over 12 h. Responses in this population of refractory gynecologic cancer patients are unusual, and these encouraging results form the basis for a Phase II trial of this combination.

Zinc supplementation during pregnancy: zinc concentration of serum and hair from low-income women of Mexican descent.

The effect of zinc supplementation on concentrations of zinc in hair and serum of 213 pregnant Hispanic women attending a clinic in Los Angeles was assessed using a random, double-blind experiment. Both the treatment (T) and control (C) groups received similar vitamin and mineral supplements except that 20 mg zinc was added to the supplements for the treatment group. Nutrient intakes were calculated from 24-h recalls. The initial mean dietary zinc intake of both groups was about 50% of the Recommended Dietary Allowance (9 +/- 5 mg). Initially there were no significant differences between the two groups in mean zinc levels in serum (66 +/- 11 micrograms/dl, C, and 65 +/- 12 micrograms/dl, T) or in hair (184 +/- 41 micrograms/g, C, and 175 +/- 38 micrograms/g, T). Zinc supplementation did not alter mean zinc levels in serum or hair but significantly (p less than 0.05) reduced the number of low serum zinc values (less than or equal to 53.3 micrograms/dl) toward the end of pregnancy. Although serum zinc levels do decline in pregnancy, our results suggest that severely depressed levels (less than or equal to 50 to 55 micrograms/dl) indicate inadequate zinc status.

Synthesis and quantitative structure-activity relationship of a novel series of small conductance Ca(2+)-activated K+ channel blockers related to dequalinium.

The synthesis, pharmacological testing, and quantitative structure-activity relationship studies of a novel series of bisquinolinium small conductance Ca(2+)-activated K+ channel blockers (23) related to dequalinium are described. In this series, two quinolinium rings are linked via the 4-position to an alpha, omega-diamino alkylene chain and the ring N atom is quaternized with a methyl or benzyl group. The exocyclic N atom can be replaced by O, S, or CH2 but with some loss of potency. The quinoline groups do not have to be quaternized for blocking activity, as long as they are basic enough to be protonated at the site of action. For the quaternary compounds, there is considerable steric tolerance for the group R attached to the ring N atom of the quinoline; a benzyl group gave the optimum potency in this series. Moreover, and in contrast to previously reported results for dequalinium analogues, there is no correlation of activity to previously reported results for dequalinium analogues, there is no correlation of activity with N1 charge or EHOMO. On the other hand, a good correlation was obtained between the blocking potency of the compounds and ELUMO [pEMR = 1.16(+/-0.26)ELUMO + 5.33(+/-01.29)(n = 11, r= 0.83, s = 0.243)]. It has been possible to combine this equation with the previously reported ELUMO correlation for a series of dequalinium analogues to include all the compounds of both series [pEMR = 1.17(+/-0.15)ELUMO +5.33(+/-0.76)(n =24, r = 0.85, s = 0.249)]. A possible physical meaning for the ELUMO correlation based upon the principle of maximum hardness is discussed.

Synthesis and structure-activity relationships of dequalinium analogues as K+ channel blockers. Investigations on the role of the charged heterocycle.

Small conductance Ca(2+)-activated K+ (SKCa) channels occur in many cells but have been relatively little studied. Dequalinium, a bis-quinolinium compound, has recently been shown to be the most potent nonpeptidic blocker of this K+ channel subtype. This paper examines the importance of the quinolinium rings for blocking activity. Analogues of dequalinium were synthesised in which one quinolinium group was removed (1 and 2) or replaced by a triethylammonium group (3). They have been assayed in vitro for their ability to block the after-hyperpolarization (mediated by the opening of SKCa channels) that follows the action potential in rat sympathetic neurones. The compound having one quinolinium and one triethylammonium group (3) showed reduced activity, and it is suggested that the stronger binding to the channel of the quinolinium relative to the triethylammonium group may be related to differences in their electrostatic potential energy maps. Two monoquaternary compounds (1 and 2) were tested, but they exhibited a different pharmacological profile that did not allow definite conclusions to be drawn concerning their potency as blockers of the SKCa channel. Replacement of both quinolinium groups by pyridinium, acridinium, isoquinolinium, or benzimidazolium reduced but did not abolish activity. These results show that compounds having a number of different heterocyclic cations are capable of blocking the SKCa channel. However, among the heterocycles studied, quinoline is optimal. Furthermore, charge delocalization seems to be important: the higher the degree of delocalization the more potent the compound.

Membranoproliferative glomerulonephritis and alpha 1-antitrypsin deficiency in children.

Two white girls had reduced serum concentration of alpha 1-antitrypsin (alpha-AT), phenotype ZZ, and liver disease. Hepatocytes exhibited the microscopic criteria of alpha-AT deficiency. Hypocomplementemia, elevated circulating immune complexes (patient 1), clinical signs of renal disease, and the histologic findings of membranoproliferative glomerulonephritis (MPGN) type I developed. Immunoglobulin A (but not alpha-AT) was demonstrable immunologically as a component of glomerular deposits in patient 1. Among 53 patients with MPGN but without clinical signs of liver disease, none had Pi type Z. Among 23 patients with phenotype ZZ but without clinical signs of kidney disease, six had abnormal complement protein levels, but the pattern did not resemble that of idiopathic MPGN type I. These results are consistent with the conclusion that MPGN in the two patients reported here is a consequence of their chronic liver disease and is not directly related to the presence of the allelic alpha-AT variant PiZ.