Local and systemic delivery of a stable aspirin-triggered lipoxin prevents neutrophil recruitment in vivo

Aspirin (ASA) triggers a switch in the biosynthesis of lipid mediators, inhibiting prostanoid production and initiating 15-epi-lipoxin generation through the acetylation of cyclooxygenase II. These aspirin-triggered lipoxins (ATL) may mediate some of ASA's beneficial actions and therefore are of interest in the search for novel antiinflammatories that could manifest fewer unwanted side effects. Here, we report that design modifications to native ATL structure prolong its biostability in vivo. In mouse whole blood, ATL analogs protected at carbon 15 [15(R/S)-methyl-lipoxin A4 (ATLa1)] and the omega end [15-epi-16-(para-fluoro)-phenoxy-LXA4 (ATLa2)] were recoverable to approximately 90 and 100% at 3 hr, respectively, compared with a approximately 40% loss of native lipoxin A4. ATLa2 retains bioactivity and, at levels as low as approximately 24 nmol/mouse, potently inhibited tumor necrosis factor-alpha-induced leukocyte recruitment into the dorsal air pouch. Inhibition was evident by either local intra-air pouch delivery (approximately 77% inhibition) or systemic delivery by intravenous injection (approximately 85% inhibition) and proved more potent than local delivery of ASA. Rank order for inhibiting polymorphonuclear leukocyte infiltration was: ATLa2 (10 micrograms, i.v.) approximately ATLa2 (10 micrograms, local) approximately dexamethasone (10 micrograms, local) >ASA (1.0 mg, local). Applied topically to mouse ear skin, ATLa2 also inhibited polymorphonuclear leukocyte infiltration induced by leukotriene B4 (approximately 78% inhibition) or phorbol ester (approximately 49% inhibition), which initiates endogenous chemokine production. These results indicate that this fluorinated analog of natural aspirin-triggered lipoxin A4 is bioavailable by either local or systemic delivery routes and is a more potent and precise inhibitor of neutrophil accumulation than is ASA.

Migraine therapy: development and testing of a patient preference questionnaire

OBJECTIVES

To develop and test a patient preference questionnaire in migraine.

METHODS

A user-friendly, self-administered questionnaire was developed to assess the relative importance of aspects of migraine therapy to patients. It was tested in a convenience sample of 66 migraineurs. The questionnaire has five sections: patient preference, migraine history, demographics, usual behavior during an attack, and migraine impact on cognition and functionality. It employs a special reverse-ranking technique to quantify preferences.

RESULTS

Sixty-six migraineurs participated: 86% were women, 53% had not consulted their doctor about migraine in the previous year; and only 51% took prescribed medication, the majority (52%) at the start of a migraine. "A medication that can be taken any time during a migraine attack" was ranked most important by 20% of the migraineurs, one that decreases pain from the unbearable level in 30 minutes by 17%, and one that relieves pain completely within 2 hours by 15%. Not being able to think or concentrate with severe symptoms was reported by 71%. Optional activities were impeded by migraine in 83% of subjects, but required activities in only 60%.

CONCLUSIONS

The patient preference questionnaire is readily completed by subjects and reveals that the dimensions of relief preferred by patients can be addressed by a self-report questionnaire.

Direct medical costs of complications resulting from type 2 diabetes in the U.S

OBJECTIVE

To estimate direct medical costs of managing the complications of type 2 diabetes.

RESEARCH DESIGN AND METHODS

Costs were estimated for 15 diabetic complications by applying unit costs to typical resource-use profiles. Resource used and unit costs were estimated from many sources, including acute care discharge databases, clinical guidelines, government reports, fee schedules, and peer-reviewed literature. For each complication, the event costs are those associated with resource use that is specific to the acute episode and any subsequent care occurring in the 1st year. State costs are the annual costs of continued management. All costs are expressed in 1996 U.S. dollars.

RESULTS

As expected, the more severe or debilitating events, such as acute myocardial infarction ($27,630 event cost; $2,185 state cost), generate a greater financial burden than do early-stage complications, such as microalbuminuria ($62 event cost; $14 state cost). Yet, complications that are initially relatively low in cost (e.g., microalbuminuria) can progress to more costly advanced stages (e.g., end-stage renal disease, $53,659 state cost); therefore, minor complications should also be considered in any economic analysis of diabetes.

CONCLUSIONS

The recent literature has lacked cost estimates that may be readily translated into patient-level cost inputs for an economic model. Emerging therapies that may reduce the incidence of some diabetic complications will need to be scrutinized economically in today's cost-conscious environment. The cost estimates from this study provide one piece of the economic analysis needed to evaluate these new interventional therapies.

Altered nociception, analgesia and aggression in mice lacking the receptor for substance P

The peptide neurotransmitter substance P modulates sensitivity to pain by activating the neurokinin-1 (NK-1) receptor, which is expressed by discrete populations of neurons throughout the central nervous system. Substance P is synthesized by small-diameter sensory 'pain' fibres, and release of the peptide into the dorsal horn of the spinal cord following intense peripheral stimulation promotes central hyperexcitability and increased sensitivity to pain. However, despite the availability of specific NK-1 antagonists, the function of substance P in the perception of pain remains unclear. Here we investigate the effect of disrupting the gene encoding the NK-1 receptor in mice. We found that the mutant mice were healthy and fertile, but the characteristic amplification ('wind up') and intensity coding of nociceptive reflexes was absent. Although substance P did not mediate the signalling of acute pain or hyperalgesia, it was essential for the full development of stress-induced analgesia and for an aggressive response to territorial challenge, demonstrating that the peptide plays an unexpected role in the adaptive response to stress.

A Schwann cell mitogen accompanying regeneration of motor neurons

Motor neurons are the only adult mammalian neurons of the central nervous system to regenerate following injury. This ability is dependent on the environment of the peripheral nerve and an intrinsic capacity of motor neurons for regrowth. We report here the identification, using a technique known as messenger RNA differential display, of an extracellular signalling molecule, previously described as the pancreatic secreted protein Reg-2, that is expressed solely in regenerating and developing rat motor and sensory neurons. Axon-stimulated Schwann cell proliferation is necessary for successful regeneration, and we show that Reg-2 is a potent Schwann cell mitogen in vitro. In vivo, Reg-2 protein is transported along regrowing axons and inhibition of Reg-2 signalling significantly retards the regeneration of Reg-2-containing axons. During development, Reg-2 production by motor and sensory neurons is regulated by contact with peripheral targets. Strong candidates for peripheral factors regulating Reg-2 production are cytokines of the LIF/CNTF family, because Reg-2 is not expressed in developing motor or sensory neurons of mice carrying a targeted disruption of the LIF receptor gene, a common component of the receptor complexes for all of the LIF/CNTF family.

NMDA and non-NMDA receptors are co-localized at excitatory synapses of rat hypoglossal motoneurons

We used whole-cell patch clamp recordings in a rat brainstem slice preparation to characterize the properties of miniature excitatory postsynaptic currents (mEPSCs) in hypoglossal motoneurons. The distinct kinetic characteristics of N-methyl-D-aspartate (NMDA) and non-NMDA receptor-mediated synaptic responses allowed us to study dual component mEPSCs mediated by the two receptor types. Using this approach, NMDA and non-NMDA receptors were found to be co-localized at the same synaptic locations. In addition, some sites contain only NMDA receptors since a large proportion of mEPSCs were apparently mediated by NMDA receptors only. Furthermore, the amplitudes of pharmacologically isolated NMDA receptor-mediated mEPSCs were highly variable in individual cells and their decay kinetics were modulated by membrane potential.

Quantitative analysis of firing properties of pyramidal neurons from layer 5 of rat sensorimotor cortex

Quantitative aspects of repetitive firing evoked by injected current steps and ramps were studied in layer 5 pyramidal neurons in brain slices of rat sensorimotor cortex to answer the following questions. Do the tonic firing properties of burst-firing and regular-spiking (nonbursting) neurons differ significantly? Does burst firing denote a discrete class of neurons or represent a continuum of firing properties? Is firing rate during the burst of action potentials related to stimulus amplitude? What aspect of the stimulus might the initial firing rate code? How stable are a neuron's firing properties over time? All recorded neurons fired tonically to a long-lasting current above a minimum value, and the tonic firing properties of most neurons were quite similar irrespective of their initial response to a current step. Only a group of high-resistance neurons had significantly different tonic firing properties. When slow current ramps (rising between 0.5 and approximately 20 nA/s) were applied, the relation between firing rate and current during the ramp was very similar to the relation between tonic firing rate and current obtained from long-lasting current steps. Low-resistance cells exhibited three distinct initial responses to a current step: fast adaptation, high-threshold bursts, and low-threshold bursts, observed in 54, 28, and 10% of recorded cells, respectively. High-resistance cells exhibited a distinctive slow adaptation of firing rate. Slowly adapting, fast-adapting (FA), and high-threshold burster (HTB) neurons exhibited no adaptation near the minimum current that evoked repetitive firing (I(o)). FA and HTB cells exhibited two-spike adaptation to a fina tonic firing rate during currents up to 1.6 times I(o). Only a higher current (2.1 times I(o)) evoked a burst in HTB cells, whereas a burst was evoked at I(o) in the low-threshold burster cells. In most cells analyzed, the initial firing rate, whatever its nature, increased monotonically with current step amplitude. The response to fast current ramps indicated that firing rate during adaptation or bursting may code rate of change of current. Repeated measurements during long-duration impalements indicated that both transient and tonic firing properties are stable over time. We discuss how the different tonic firing properties of large and small pyramidal neurons could be more important functionally than the different transient responses (burst/nonburst) of the large neurons. We conclude that the large neurons would perform a better linear transduction of time-varying synaptic current that reaches their somata. We compare the responses evoked by somatically injected current with those evoked by dendritic glutamate iontophoresis in previous studies.

Effects of albumin on the disposition of morphine and morphine-3-glucuronide in the rat isolated perfused liver

1. The effect of albumin on the disposition of morphine and hepatically generated morphine-3-glucuronide (M3G) was investigated in the single-pass rat isolated perfused liver. 2. Using a balanced cross-over design, each of 10 livers was perfused at 30 mL/min with medium containing 2.7 mumol/L morphine in the presence and absence of 10 g/L bovine serum albumin (BSA). 3. Both bile flow rate and hepatic oxygen consumption were significantly higher (P < 0.005) when BSA was present in the perfusion medium, suggestive of a change in the functional performance of the perfused liver. 4. The binding of morphine and M3G was negligible in both BSA-free and -containing perfusate. 5. Outflow perfusate contained both morphine and M3G, while the metabolite but not morphine was found in bile. The recovery of the administered morphine was approximately 100% and was not altered (P > 0.05) by the presence or absence of BSA. 6. The fraction of morphine escaping heptic extraction in the absence of BSA (mean +/- SD; 0.41 +/- 0.14) was not altered significantly (P > 0.05) by the presence of the protein in perfusate (0.35 +/- 0.13), indicating no change in the intrinsic clearance or morphine despite the difference in oxygen consumption. 7. The fraction of hepatically generated M3G excreted in bile was significantly higher (P < 0.005) when BSA was present in the perfusate than when it was not (0.44 +/- 0.14 vs 0.38 +/- 0.16, respectively). 8. The results are consistent with the concept that BSA modifies the ability of solutes, including M3G, to move through the paracellular pathway from the canalicular to the vascular space. 9. It is concluded that because albumin may modify not only the unbound fraction of a ligand in perfusate, but also the functional performance of the liver, care is needed in the interpretation of studies examining the influence of the protein on the hepatic disposition of drugs and their metabolites.

The cytoplasmic tail of NSP4, the endoplasmic reticulum-localized non-structural glycoprotein of rotavirus, contains distinct virus binding and coiled coil domains

The final steps in the assembly of rotavirus occur in the lumen of the endoplasmic reticulum (ER). Targeting of the immature inner capsid particle (ICP) to this compartment is mediated by the cytoplasmic tail of NSP4, a non-structural virus glycoprotein located in the ER membrane. To delineate structural and functional features of NSP4, soluble fragments of the cytoplasmic tail have been expressed and purified. Our analysis combines a functional assay for ICP binding with biochemical and CD spectroscopic studies to examine the secondary and quaternary structure. The ICP-binding domain is located within the C-terminal 20 amino acids of the polypeptide. A second region, distinct from this receptor domain, adopts an alpha-helical coiled coil structure and mediates the oligomerization of the virus binding domains into a homotetramer. The domain organization of the cytoplasmic fragments of NSP4 suggests a novel structure for an icosahedral virus receptor protein in which C-terminal binding sites for immature rotavirus particles are connected to an alpha-helical coiled coil stalk which projects from the ER membrane.

The disposition of morphine and morphine-3-glucuronide in the isolated perfused rat liver: effects of altered perfusate flow rate

The rat single-pass isolated perfused liver preparation was used to study the effects of altered perfusate flow rate on the hepatic disposition of morphine and its polar metabolite morphine-3-glucuronide (M3G). Using a balanced, cross-over design, livers of female Sprague-Dawley rats (n = 6) were perfused at 15 and 30 mL min-1 with erythrocyte- and protein-free perfusion medium containing a constant concentration of morphine (2.7 microM). After reaching steady-state, inflow and outflow perfusate and bile samples were collected and morphine and M3G were measured by HPLC. Doubling of perfusate flow rate was associated with a significant increase (P < 0.05) in the availability of morphine (mean +/- s.d. of 0.19 +/- 0.06 at 15 mL min-1 and 0.29 +/- 0.08 at 30 mL min-1). The magnitude of the change in morphine availability was consistent with the predictions of the well-stirred model of hepatic elimination. The fate of hepatically generated M3G was assessed by the biliary extraction ratio of M3G; alterations in perfusate flow rate had no significant effect on this ratio (mean +/- s.d. of 0.49 +/- 0.14 at a perfusate flow rate of 15 mL min-1 and 0.47 +/- 0.22 at 30 mL min-1). A physiologically-based mathematical model, in which the vascular and intracellular spaces of the liver were represented by two well-mixed compartments, was utilized to derive an equation for the biliary extraction ratio of M3G. According to the model, the value of this extraction ratio will become insensitive to changes in perfusate flow rate when the permeability for M3G of the membrane separating the intracellular and vascular compartments is low compared with perfusate flow rate. Hence, the experimental results are consistent with the concept that the hepatic sinusoidal membrane represents a diffusional barrier to M3G.

Quinoxapeptins: novel chromodepsipeptide inhibitors of HIV-1 and HIV-2 reverse transcriptase. I. The producing organism and biological activity

Quinoxapeptin A and B are novel chromodepsipeptides which were isolated from a nocardioform actinomycete with indeterminant morphology. Quinoxapeptins A and B are potent inhibitors of HIV-1 and HIV-2 reverse transcriptase and almost equally active against two single mutants forms as well as a double mutant form of HIV-1 reverse transcriptase. Quinoxapeptin A and B are specific inhibitors of HIV-1 and HIV-2 reverse transcriptase because they did not inhibit human DNA polymerase alpha, beta, gamma and delta. Quinoxapeptin A and B are structurally similar to luzopeptin A which was also active against HIV-1 and HIV-2 reverse transcriptase.

Pharmacology of L-744,453, a novel nonpeptidyl endothelin antagonist

L-744,453 ((+/-)3-[4-(1-carboxy-1-(3,4-methylenedioxyphenyl)methoxy)-3,5-diprop ylphenyl methyl]-3H-imidazo[4,5-c]pyridine) is an endothelin (ET) receptor antagonist from a new structural class, the dipropyl-alpha-phenoxyphenylacetic acid derivatives. L-744,453 competitively and reversibly inhibits [125I]-ET-1 binding to Chinese Hamster Ovary cells expressing cloned human ET receptors (K(i)s: hET(A)=4.3 nM; hET(B)=232 nM), and is selective for endothelin receptors compared to other peptide receptors. It is an antagonist of ET-1 stimulated phosphatidyl inositol hydrolysis in rat uterine slices (IC50=220 nM) and exhibits no agonist activity. This compound also inhibits ET-1 stimulated contraction of rat aortic rings with a K(b) value of 50 nM. L-744,453 protects against ET-1 induced lethality in mice after i.v. (AD50=13 mg/kg i.v.) or oral administration. This compound also antagonizes ET-1 induced increases in diastolic blood pressure in conscious normotensive rats (AD50=0.67 mg/kg i.v.) and anesthetized ferrets (AD50=1.6 mg/kg i.v.). L-744,453 is a potent, selective, orally active endothelin antagonist which may be useful in elucidating the role of endothelin in normal and pathophysiological states.

The cost of treating heart valve related complications

BACKGROUND AND AIM OF THE STUDY

Heart valve replacement can result in serious complications. Therefore, it is important in decision making regarding the choice of valves to know the cost of such complications.

METHODS

Complications were defined according to guidelines proposed by the Society of Thoracic Surgeons. They included valve thrombosis, embolism, hemorrhage due to anticoagulation, non-structural dysfunction, structural deterioration and endocarditis. The costs of the pre-admission assessment, acute inpatient stay, inpatient physician fees, post-discharge and out-patient physician fees were estimated for each complication to determine the average total cost in 1995 US dollars. Cost inputs were obtained from existing Massachusetts databases and Medicare fee schedules.

RESULTS

The costs of managing valve thrombosis, endocarditis and non-structural dysfunction were all estimated to exceed $30,000 for a single event. The costs of acute management of embolism and anticoagulant-related hemorrhage were between $8,000 and $11,500. However, it is of note that managing the sequelae of an embolism was calculated to be greater than $70,000 over 15 years. The greatest contributor to the average cost of treating a complication was determined to be the in-patient facility cost.

CONCLUSIONS

Complications related to heart valve replacement can be very costly to manage in both the short term and the long term.

Bileaflet valve replacement: complications and costs

A meta-analysis of the available literature on the CarboMedics and St. Jude Medical valves was conducted to compare their clinical performance. Frequency of valve-related complications for aortic, mitral, and double-valve replacements served as a measure of performance. An economic model was created to estimate the economic impact of valve-related complications. Overall, fewer events occurred with the St. Jude Medical valve than with the CarboMedics valve. As a result, use of the St. Jude Medical valve is expected to save up to $13,201 over 10 years.

Pharmacology of L-754,142, a highly potent, orally active, nonpeptidyl endothelin antagonist

L-754,142, (-)-N-(4-iso-propylbenzenesulfonyl)-alpha-(4-carboxyl-2-n-propy lphenoxy)-3,4- methylenedioxyphenylacetamide, is a potent nonpeptidyl endothelin antagonist (e.g., Ki: cloned human ETA = 0.062 nM: cloned human ETB = 2.25 nM), with high specificity for endothelin receptors. In vitro, L-754,142 is a potent antagonist of ET-1-induced phosphatidyl inositol hydrolysis in Chinese hamster ovary cells expressing cloned human endothelin receptors (IC50: hETA = 0.35 nM; hETB = 26 nM) and of ET-1 induced contractions in rabbit iliac artery rings (pA2 = 7.74) and rat aortic rings (pA2 = 8.7). In vivo, L-754,142 is a potent and specific antagonist of exogenously administered ET-1 or big ET-1, L-754,142 fully protects against ET-1-induced lethality in mice (AD50 = 0.26 mg/kg i.v.). The pressor response to big ET-1 in the anesthetized ferret is blocked by this compound with an ED50 value of 0.019 mg/kg i.v. L-754,142 also blocks the pressor response to big ET-1 in the conscious rat with ED50 values of 0.30 mg/kg i.v. and 0.56 mg/kg p.o. The duration of action of L-754,142 in this rat model is more than 12 hr after an oral dose of 3 mg/kg. In summary, L-754,142 is a potent, orally active ET antagonist with a long duration of action in several in vivo models.

Conventional patterns of human intestinal proliferation in a severe-combined immunodeficient xenograft model

The present work describes the pattern of human intestinal proliferation in an immunodeficient murine xenograft model, which we have shown to closely mimic cell division in normal paediatric gut. Cellular proliferation was measured using a double-label technique combining MIB-1 immunohistochemistry and [3H]thymidine autoradiography, to critically compare values for the tissue growth fraction (G1, G2, S- and M-phase cells) and DNA synthesizing (S-phase) cells in xenograft epithelium, lamina propria, muscularis externa and intraepithelial lymphocytes. The MIB-1 monoclonal antibody (which recognises the cell-cycle dependent nuclear antigen Ki-67) specifically labelled proliferating human cells within the xenografts and did not cross-react with dividing murine cells. This was confirmed using ultrastructural in situ hybridisation with human- and mouse-specific DNA probes to identify the genetic origin of proliferating cells. In general, we found a good tissue correlation between MIB-1 and [3H]thymidine labelling, the only exception being an apparent dysregulation of Ki-67 antigen expression in regenerating xenograft epithelium. In developed xenograft intestine, the highest levels of proliferation were consistently recorded within the crypt epithelium, where 15.7%-26.7% of cells were actively cycling and S-phase occupied approximately half of the cell cycle. The frequency distribution of proliferating epithelial cells within small and large intestinal xenograft crypts was clearly tissue-specific, showing typical patterns of cell division. Therefore, the presence of functional pluripotent epithelial stem cells and conventional spatio-temporal patterns in cellular proliferation, migration, de-cycling, lineage commitment and cytodifferentiation now makes this an attractive experimental model with which to study human intestinal crypt responses to various types of tissue manipulation, e.g. cytotoxic, radiotherapeutic, dietary, endocrine and gene-targeting therapy.

Characterization of the human oxytocin receptor stably expressed in 293 human embryonic kidney cells

The human oxytocin (OT) receptor was stably expressed in 293 embryonic kidney cells (293/OTR), characterized pharmacologically and compared to human uterine myometrial receptors. The cloned receptor is expressed at a reasonably high density (0.82 fmole/microgram protein) and exhibits high affinity for [3H]OT (Kd = 0.32nM), similar to the value found in human myometrial tissue. The rank-order of potency for various antagonist and agonist ligands from several structural classes is also similar between the cloned and native receptor, as seen in a comparison of their inhibitory constants for [3H]OT binding. Agonist affinity at the cloned OT receptor is decreased by guanine nucleotide analogs, demonstrating functional G-protein-coupling. The OT receptor in 293 cells, like in human myometrium, is also coupled to the inositol phosphate pathway. In 293/OTR cells, OT stimulates inositol phosphate accumulation with an EC50 = 4.1 nM, an effect blocked by a potent and selective OT antagonist, L-366,948. Additionally, the cloned receptor in 293 cells desensitizes to high concentrations of OT, similar to the desensitization in myometrial tissue and also described for several other G-protein-coupled receptors. These results illustrate the utility of the 293 cell line for expressing human OT receptors in an environment quite comparable to the native myometrial tissue.

Impaired cell volume regulation in intestinal crypt epithelia of cystic fibrosis mice

Cystic fibrosis is a disease characterized by abnormalities in the epithelia of the lungs, intestine, salivary and sweat glands, liver, and reproductive systems, often as a result of inadequate hydration of their secretions. The primary defect in cystic fibrosis is the altered activity of a cAMP-activated Cl- channel, the cystic fibrosis transmembrane conductance regulator (CFTR) channel. However, it is not clear how a defect in the CFTR Cl- channel function leads to the observed pathological changes. Although much is known about the structural properties and regulation of the CFTR, little is known of its relationship to cellular functions other than the cAMP-dependent Cl- secretion. Here we report that cell volume regulation after hypotonic challenge is also defective in intestinal crypt epithelial cells isolated from CFTR -/- mutant mice. Moreover, the impairment of the regulatory volume decrease in CFTR -/- crypts appears to be related to the inability of a K+ conductance to provide a pathway for the exit of this cation during the volume adjustments. This provides evidence that the lack of CFTR protein may have additional consequences for the cellular function other than the abnormal cAMP-mediated Cl- secretion.

Synthesis of a series of 4-(arylethynyl)-6-chloro-4-cyclopropyl-3,4-dihydroquinazolin-2(1H)-ones as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

As part of an ongoing effort to prepare novel non-nucleoside inhibitors of human immunodeficiency virus type-1 (HIV-1) reverse transcriptase (RT), a series of 4-(arylethynyl)-6-chloro-4-cyclopropyl-3,4-dihydroquinazolin -2(1H)-ones 4aa-l has been prepared. Target compounds 4a-e were synthesized via addition of various 1-lithio-2-(aryl)alkyne nucleophiles to a 1-protected-4-cyclopropylquinazolin-2(1H)-one (7), followed by deprotection. The 3-methyl compound 4aa was prepared in an analogous manner, with the 3-alkylation performed prior to deprotection. Alternatively, the target compounds 4f-l were prepared by addition of 1-lithio-2-(trimethylsilyl)acetylene to 7, followed by deprotection and subsequent palladium-catalyzed coupling with various aryl halides. By incorporating an aryl group onto the end of the 4-acetylene functionality, the requirement for a metabolically labile 3-methyl group on the dihydroquinazolinone nucleus has been eliminated. A number of the target compounds were shown to be potent inhibitors of HIV-1 RT. Compound 4a, which had exhibited the most favorable overall biological profile, was resolved via a four-step procedure to provide the enantiomers 13a and 13b. Compound 13a having the (-)-4(S) configuration was shown to be the active enantiomer and was selected as a candidate for further investigation.

Metabolism of 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2 (1H)-one (L-696,229), an HIV-1 reverse transcriptase inhibitor, by rat liver slices and in humans

Healthy subjects were administered single oral doses of 800 mg or 400 mg 3-[2-(benzoxazol-2-yl)ethyl]-5-ethyl-6-methylpyridin-2(1H)-o ne (L-696,229), a nonnucleoside inhibitor of the human immunodeficiency virus-type 1 (HIV-1) reverse transcriptase (RT). Plasma or urine samples were collected over a period of 48 hr. Pooled plasma (0.5-6 hr) and urine (0-24 hr) samples were analyzed by HPLC-UV and HIV-1 RT inhibition assay using poly rC.dG as a template primer. The parent compound and several common metabolites were detected in both samples. The metabolic profiles were also similar to those obtained from a rat liver slice incubation with [3H]L-696,229. The in vitro metabolites were identified by NMR and MS as 5 alpha-hydroxyethyl- (major), 5,6-dihydrodiol-, 6'-hydroxy-, 6-hydroxymethyl-, and 5-vinyl analogs, and a benzoxazole ring hydrolysis product. Most of the significant metabolites in human plasma and urine were found to be identical to the in vitro metabolites, as established by HPLC-UV and MS. Hydrolysis of the plasma and urine with beta-glucuronidase/sulfatase indicated the presence of significant amounts of conjugates of the parent compound and 5 alpha-hydroxyethyl metabolite. Most of the other primary metabolites were also present in conjugated forms, albeit in small quantities. In addition, two secondary metabolites were isolated and identified from the hydrolyzed urine as 5-acetyl-6'-hydroxy- and 5 alpha-hydroxyethyl-6-hydroxymethyl- analogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered renovascular resistance after spontaneous recovery from hemolytic uremic syndrome

Twenty-three patients were evaluated from 1-15 (mean 6) years after recovering from an episode of diarrhea-associated associated childhood hemolytic uremic syndrome (DA-HUS). All patients had received only conservative treatment; none had been given experimental, anti-coagulant, or immunological therapies. Follow-up studies included morphologic and duplex Doppler sonograms. Doppler sonography was used to determine the resistive index, a measure of renovascular resistance. Histories and physical examinations revealed no abnormalities. Results of laboratory studies, which included calculated glomerular filtration rates, were all within normal limits, except for one patient with minor urinary abnormalities. Renal sonograms showed no significant abnormalities of kidney length or parenchymal appearance. However, Doppler sonographic examinations revealed that the DA-HUS patients demonstrated less of a decrease in renovascular resistance with age than did the control group (p < 0.0002). After recovery, patients treated exclusively with conservative management during an acute episode of DA-HUS appeared to have an excellent long-term prognosis. Comparison of our results with those from other studies in which investigational therapies have been used during the acute phase of DA-HUS suggests that latent toxicities which cause long term sequelae may not have been appreciated previously. The clinical significance of the altered renal vascular resistance remains to be delineated.

Inactivation of the murine cftr gene abolishes cAMP-mediated but not Ca(2+)-mediated secretagogue-induced volume decrease in small-intestinal crypts

The cellular volume of crypts isolated from 2- to 3-week-old mouse small intestine has been measured to assess the capacity of the epithelial cells to respond to secretagogues. Vasoactive intestinal polypeptide (VIP) or carbachol, respectively cAMP- and calcium-mediated secretagogues, produced a reduction crypt volume attributed to KCl loss through channels activated by the agonists. Consistent with the participation of separate chloride channels, 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) blocked the carbachol- but not the VIP-induced volume decrease, whilst glibenclamide abolished the VIP effect without affecting the carbachol-induced volume decrease. Animals homozygous for a disrupted cftr gene, introduced by gene targeting, were also used as the source for crypt isolation. In these CFTR (-/-) crypts. VIP failed to elicit any reduction in cellular volume, while the response to carbachol was indistinguishable from that seen in crypts from age-matched control animals. These results are consistent with murine CFTR being a cAMP-activated chloride channel inhibited by glibenclamide and resistant to DIDS. A separate chloride conductance activated by calcium mobilization in small-intestinal crypts appears to be independent of CFTR.

Biotransformation of 5-chloro-3-phenylthioindole-2-carboxamide (L-734,005) in rhesus monkeys and rat liver microsomes to a potent HIV-1 reverse transcriptase inhibitor

Rhesus monkeys were dosed orally with 10 mg/kg 5-chloro-3-phenylthioindole-2-carboxamide (L-734,005), a nonnucleoside human immunodeficiency virus type 1 (HIV-1) reverse transcriptase inhibitor, in polyethylene glycol 300. Plasma samples from these monkeys demonstrated greater bioactivity in an HIV-1 reverse transcriptase inhibition assay than anticipated from the parent compound concentrations as determined by an HPLC-UV assay. One major and three minor metabolites, as well as the parent compound, were detected in the plasma. One of the minor metabolites was determined to be several-fold more active, and the major metabolite one-half as active as the parent compound in the inhibition assay. Identical metabolites were formed during an incubation of L-734,005 with rat liver microsomes. The most active minor metabolite was identified as a sulfone analog (L-737,126) of the parent compound by NMR and MS analyses. The less active major metabolite and two relatively inactive minor metabolites were similarly identified as the sulfoxide, 4-hydroxythiophenyl and 6-hydroxyindole analogs of L-734,005. The synthetic sulfone analog was highly potent against HIV-1, with a 95% inhibitory concentration of 3.0 nM for the spread of virus infection in a cell culture.