Kappa-opioid receptor modulation of nicotine-induced behaviour

The ability of kappa-opioid receptor ligands to modulate dependence-related behavioural effects of drugs like morphine and cocaine is well documented. The present study examined the effects of kappa-opioid agonists on nicotine-induced locomotor stimulation in rats chronically pre-exposed to nicotine (0.4 mg/kg/day). U50,488 [0.5-3 mg/kg subcutaneously (s.c.)], U69,593 [0.08-0.32 mg/kg intraperitoneally (i.p.)] and CI-977 (0.005-0.02 mg/kg s.c.) administered 30 min prior to nicotine (0.06, 0.2 and 0.4 mg/kg s.c.) dose-dependently antagonised its acute locomotor-activating effect, which was completely prevented by the highest tested dose of each agonist. Baseline activity was unaffected by the largest doses of U50,488 and U69,593, but it was reduced by 0.01 and 0.02 mg/kg of CI-977. The selective kappa-opioid receptor antagonist nor-BNI [30 microg intracerebroventricularly (i.c.v.)] blocked the effects of U69,593 on nicotine-induced behaviour, thus supporting the involvement of kappa-opioid receptors in this effect. In conclusion, the activation of kappa-opioid receptors clearly prevented nicotine-induced locomotor stimulation. The effects of at least two of the kappa-opioid agonists were not due to a general motor suppression. It is suggested that the mechanism entails a depression of nicotine-induced increases in accumbal dopamine by these compounds. The results should encourage further research on the role of the kappa-opioid system in the behavioural and neurochemical effects of nicotine, including those related to nicotine dependence.

Nicotine in an animal model of attention

Studies in smokers have suggested that at least part of the improved psychomotor performance produced by nicotine is the result of an effect on attention. Many animal experiments have assessed the effects of nicotine and its antagonists on diverse types of learning and memory but relatively few have looked at it in tasks designed to assess attention. In a five-choice serial reaction time task (5-CSRTT), rats with restricted access to food were presented with an array of five holes; illumination of a randomly selected hole signalled that a nose-poke into it would be reinforced by food presentation. Initially, signal length and the inter-trial interval (ITI) were varied and the procedure was demonstrated to satisfy some criteria for a vigilance task. The effects of nicotine on deficits in performance induced by varying signal length and ITI were assessed. Under appropriate conditions, small doses of nicotine increased the percentage of correct responses (accuracy), decreased omission errors and reaction time, and increased anticipatory responses. Subsequently, the effects of varying the ITI were examined more extensively in a slightly modified task. Here, nicotine produced small but robust, highly significant dose-related increases in accuracy, as well as decreases in omission errors and reaction times. Nicotine also increased accuracy when light stimuli were presented in an unpredictable manner. The nicotine antagonist mecamylamine produced a modest deficit in reaction time only. It is concluded that appropriate doses of nicotine can produce robust improvements in performance of normal rats in an attentional task. The effect cannot be attributed easily to changes in sensory or motor capability, learning or memory and may provide the measures needed to investigate the neuropharmacological and neuroanatomical bases of the elusive attentional effect of nicotine.

N-methyl-D-aspartate-type glutamate receptors are found in post-synaptic targets of adrenergic terminals in the thoracic spinal cord

Adrenergic (C1) neurons in the rostral ventrolateral medulla (RVL) are sympathoexcitatory and project directly to sympathetic preganglionic neurons (SPNs) in the thoracic spinal cord. C1 neurons also contain glutamate which may mediate the excitatory effects of RVL stimulation on SPNs through the N-methyl-D-aspartate (NMDA)-type receptor. Dual-labeling immunocytochemistry, combined with electron microscopy, was used to determine if NMDA receptors are located post-synaptic to adrenergic terminals in the spinal cord. Adrenergic terminals were labeled using an antibody directed against phenylethanolamine-N-methyl transferase (PNMT) and the NMDA receptor was identified using an antibody directed against the R1 subunit of the receptor (NMDAR1). NMDAR1 was found primarily in large and small dendrites and a few perikarya. The presence of NMDAR1 in the dendritic targets of PNMT-containing terminals was quantified in spinal cords sectioned either horizontally or coronally. PNMT-labeled terminals formed asymmetric synapses on dendrites containing immunogold labeling for NMDAR1, but NMDAR1 was more often detected in the targets of PNMT terminals when spinal cords were sectioned horizontally (59%) rather than coronally (28%). This difference in prevalence of NMDAR1 in targets of PNMT terminals is likely due to the preferential orientation of SPN dendrites in the horizontal plane, since longer dendritic shafts were visible in horizontal sections. When NMDAR1 was present in the dendritic targets of many adrenergic terminals, it was usually located at sites distal to the adrenergic input. We conclude that NMDA receptor ligands are likely to modulate the activity of dendritic targets of adrenergic terminals in the spinal cord, but are not closely associated with adrenergic synaptic input.

Gene-marked autologous hematopoietic stem cell transplantation of autoimmune disease

In phase I (safety) trials, we have demonstrated the feasibility of autologous hematopoietic stem cell transplantation (HSCT) for patients with autoimmune diseases. Although this review comments on results of our phase I trials, the focus is on phase II (efficacy) trials using gene-marked autologous stem cells.

Recurrent symptoms and gastro-oesophageal reflux disease in patients with duodenal ulcer treated for Helicobacter pylori infection

BACKGROUND

Eradication of Helicobacter pylori has been shown to prevent relapse of endoscopically detected duodenal ulcers. There is controversy regarding symptom improvement after therapy. Some studies have suggested that a substantial number of patients remain symptomatic after eradication therapy. Other studies suggest that gastro-oesophageal reflux disease (GERD) may develop as a result of H. pylori eradication.

AIM

To determine the relationship between symptoms and H. pylori eradication and to determine whether H. pylori eradication results in symptoms or endoscopic findings of GERD.

METHODS

Two hundred and forty-two patients with endoscopically documented duodenal ulcer disease and evidence of H. pylori infection by rapid urease testing and histology were studied in four randomized, placebo-controlled, double-blind trials of H. pylori eradication therapy. All patients underwent symptom assessment and endoscopy with biopsy before therapy and 1 and 6 months after completing therapy. The rapid urease test and histology were used to determine H. pylori status. Interviewers were blinded to H. pylori status after eradication and were unaware of the endoscopic findings (interviews were performed prior to repeat endoscopy).

RESULTS

The presence of epigastric pain was significantly associated with persistent H. pylori infection 1 month after therapy (odds ratio 2.3, 95% CI: 1.02-5.2; P=0.041), as was nausea (OR 7.1, 95% CI: 0.93-55.6; P=0.029). The presence of epigastric pain was significantly associated with ulcer relapse at 6 months (OR 7.5, 95% CI: 3.6-15.7; P < 0.001) as was nausea (OR 5.1, 95% CI: 1.7-16.0; P=0.002). Heartburn was not associated with eradication of H. pylori or ulcer relapse. New onset reflux symptoms were reported by 17% (17 of 101 patients) at 6 months and were not significantly different in patients with (15%) and without (22%) persistent H. pylori infection (P=0.47). Erosive oesophagitis was present at endoscopy in one of the 17 cases that developed new heartburn.

CONCLUSIONS

One month after completion of therapy, the presence of epigastric pain or nausea is associated with persistent infection and these symptoms at 6 months are suggestive of duodenal ulcer relapse. The incidence of GERD is not increased in patients who have eradication of H. pylori.

Distinct human immunodeficiency virus strains in the bone marrow are associated with the development of thrombocytopenia

We analyzed bone marrow and blood from human immunodeficiency virus type 1 (HIV-1)-infected individuals and described the HIV-1 quasispecies in these cellular compartments. HIV-1 isolates from the bone marrow of thrombocytopenic patients contained distinct amino acids in the V3 loop and infected T-cell lines, implicating this virus in the development of thrombocytopenia.

Irritable bowel syndrome symptom patterns: frequency, duration, and severity

We examined symptom frequency, duration, and severity, as well as episode patterns, in 122 adult patients with irritable bowel syndrome in a 12-week study conducted in the United States, the United Kingdom, and The Netherlands. Patients used an interactive telephone data entry system daily to report symptoms. Data from 59 of the patients meeting inclusion criteria are presented, the remainder having been excluded for failing to complete at least 70 days of symptom reporting. The majority of patients experienced at least one symptom on over 50% of the reported days; however, individual symptoms were reported on less than 50% of the days, indicating that symptoms sometimes occurred sequentially rather than always simultaneously. On average, patients reported pain/discomfort on 33% of days, bloating on 28% of the days, altered stool form or stool passage on 25% and 18% of the days, respectively, and mucus on 7% of the days. The duration of symptoms was relatively short, with pain/discomfort and bloating lasting the longest, an average of five days each per episode. All symptoms but one (mucus) were moderately severe on the majority of reported days. Patients experienced an "episode" (defined as a period of days with symptoms bounded by one or more symptom-free days) on an average of 12.4 times during the study, but the duration of these episodes varied greatly among patients. These results further establish the chronic nature of irritable bowel syndrome and the burden that this condition imposes on patients.

Clarithromycin-resistant Helicobacter pylori in patients with duodenal ulcer in the United States

BACKGROUND

Clarithromycin is a key component of several antimicrobial treatment regimens for Helicobacter pylori. Cure rates with clarithromycin-containing regimens are significantly decreased when resistance is present. Resistance develops by a point mutation in the ribosomal RNA of some organisms exposed to clarithromycin. We studied the prevalence of clarithromycin-resistant organisms in patients with duodenal ulcer in the United States from 1993-96.

METHODS

Patients with endoscopic evidence of a duodenal ulcer were studied. Gastric biopsies were cultured for H. pylori and antimicrobial sensitivity was determined by the E-test (epsilometer agar diffusion gradient).

RESULTS

In 1993-94, three of 78 patients (4%) had clarithromycin-resistant strains of H. pylori. In 1995-96, 44 of 348 patients (12.6%; p = 0.025) had resistant strains of H. pylori. Patients who had previously failed antimicrobial treatment for H. pylori accounted for much of the increase in resistant strains (25%).

CONCLUSIONS

Failed therapy with clarithromycin-based regimens is a growing cause of antimicrobial resistance in H. pylori in the United States. Whereas the overall rates of primary resistance are low, the increase in secondary resistance over a short period of time is worrisome. New treatments that prevent the emergence of resistance may be important in the future.

Differential association of uracil DNA glycosylase with SIVSM Vpr and Vpx proteins

The HIV-1 Vpr protein is a virion-associated protein which has been shown to facilitate infection of nondividing macrophages and additionally to alter cell cycle and proliferation status of the infected host cell. HIV-1 Vpr also was recently shown to associate with the DNA repair enzyme uracil DNA glycosylase (UDG). This association with a DNA repair enzyme is intriguing given that nonprimate lentiviruses encode a dUTPase, which, like UDG, minimizes the misincorporation of uracil into DNA and is important for virus replication in primary nondividing macrophages but not in dividing cells. This raises the possibility that the dependence upon Vpr for infection of nondividing macrophages may relate to its ability to interact with UDG. Members of the HIV-2/SIVSM group encode, in addition to Vpr, a related protein called Vpx. We previously demonstrated (Fletcher et al., 1996) that Vpx of HIV-2/SIVSM is necessary and sufficient for infection of primary macaque macrophages, while Vpr is not required for macrophage infection but governs cell cycle arrest. Here, we extend on these observations by demonstrating that Vpr, but not Vpx of HIV-2/SIVSM, associates with UDG, which suggests that Vpx facilitates infection of macrophages by a UDG-independent mechanism.

Single-dose pharmacokinetics of thalidomide in human immunodeficiency virus-infected patients

The pharmacokinetics of thalidomide in nine human immunodeficiency virus-infected patients were studied. Single doses of thalidomide were well absorbed, with mean peak concentrations (+/- standard deviations) of 1.17 +/- 0.21 and 3.47 +/- 1.14 microg/ml in the 100- and 300-mg dosing groups, respectively, and the mean elimination half-life was approximately 6 h. Adverse effects were mild, with drowsiness being reported for seven of nine patients.

HIV type 1 subtypes, coreceptor usage, and CCR5 polymorphism

Identification of the chemokine receptors CCR5 and CXCR4 as the major coreceptors for HIV-1 entry has greatly assisted our understanding of HIV-1 pathogenesis, transmission, and tropism. However, most of our current knowledge on coreceptor usage comes from studies using HIV-1 strains or env genes derived from the genetic subtype B predominant in North America and western Europe. In this report, the coreceptor usage of 20 primary viral isolates representative of genetic subtypes A, B, C, D, E, and group O was examined. Thirty-nine full-length CCR5 sequences from individuals of diverse geographic origins were also obtained to examine the possible effect of CCR5 polymorphism on HIV-1 subtype distribution. Our results indicate that (1) CCR5 and CXCR4 serve as the two major coreceptors for viruses belonging to HIV-1 subtypes A, B, C, D, E, and group O, whereas other chemokine receptors such as CCR2b and CCR3 play only a minor role in facilitating viral entry into stimulated PBMCs; (2) the coreceptor usage is determined by the viral phenotype rather than its genotype because all NSI strains, irrespective of their subtype classification, utilize CCR5, whereas all SI strains are able to use CXCR4; and (3) there is no geographic clustering of CCR5 polymorphism in different ethnic populations, suggesting that CCR5 diversity is not the underlying explanation for differences in the spread of different HIV-1 subtypes. Therefore, the uneven worldwide distribution of HIV-1 subtypes is more likely the result of stochastic dissemination.

Destroying retroviruses from within

One strategy for neutralizing retroviral infectivity is to induce the incorporation of lethal fusion proteins, such as capsid protein-nuclease fusions, into the virion during the normal viral assembly process. Genes encoding such antiviral fusion proteins must be nontoxic to the host, lethal to the virus, and must be efficiently delivered to, and expressed in, appropriate target cells.

Sequence heterogeneity of Nef transcripts in HIV-1-infected subjects at different stages of disease

Nef transcripts were analyzed from peripheral blood mononuclear cells of 10 HIV-1-infected subjects with 9-822 CD4+ lymphocytes/cu mm, including 4 individuals with a probable common source infection. There was no relationship between the phylogenetic position of the various nef sequences and the disease state of the person from whom they were derived. The nef open reading frame was disrupted in all three clones from only 1 subject. Functional analyses of a representative clone from each of the remaining 9 subjects showed that all nef alleles were capable of CD4 cell surface down-regulation, but only three nef alleles suppressed the induction of IL-2 transcription.

Increased envelope spike density and stability are not required for the neutralization resistance of primary human immunodeficiency viruses

Previous observations that the gp120 envelope glycoprotein contents of some primary, clade B human immunodeficiency virus type 1 (HIV-1) isolates were higher than those of laboratory-passaged HIV-1 isolates suggested the hypothesis that increased envelope glycoprotein spike density or stability contributes to the relative neutralization resistance of the primary viruses. To test this, the structural, replicative, and neutralization properties of a panel of recombinant viruses with HIV-1 envelope glycoproteins from divergent clades were examined in an env complementation assay. In this system, although the spike density and stability of envelope glycoproteins from primary HIV-1 isolates were not greater than those from a laboratory-adapted isolate, relative resistance to neutralizing antibodies and soluble CD4 was observed for the viruses with primary envelope glycoproteins. Thus, neither high envelope glycoprotein spike density nor stability is necessary for the relative neutralization resistance of primary HIV-1 viruses.

Vpr-induced cell cycle arrest is conserved among primate lentiviruses

We previously reported that expression of human immunodeficiency virus type 1 strain NL4-3 (HIV-1(NL4-3))vpr causes cells to arrest in the G2 phase of the cell cycle. We examined the induction of cell cycle arrest by other HIV-1 isolates and by primary lentiviruses other than HIV-1. We demonstrate that the vpr genes from tissue culture-adapted or primary isolates of HIV-1 are capable of inducing G2 arrest. In addition, we demonstrate that induction of cell cycle arrest is a conserved function of members of two other groups of primate lentiviruses, HIV-2/simian immunodeficiency virus strain sm (SIVsm)/SIVmac and SIVagm. vpr from HIV-1, HIV-2, and SIVmac induced cell cycle arrest when transfected in human (HeLa) and monkey (CV-1) cells. vpx from HIV-2 and SIVmac did not induce detectable cell cycle arrest in either cell type, and SIVagm vpx was capable of inducing arrest in CV-1 but not HeLa cells. These results indicate that induction of cell cycle perturbation is a general property of lentiviruses that infect primates. The conservation of this viral function throughout evolution suggests that it plays a key role in virus-host relationships, and elucidation of its mechanism may reveal important clues about pathology induced by primary lentiviruses.

[PDGF-induced effect on cytosolic free calcium concentration of cultured retinal pericytes]

Although the selective loss of retinal pericytes has long been known to be one of the earliest histopathological findings in diabetic retinopathy, only limited information is available concerning their function and cell biology. Recently, it has been shown that the interaction of endothelial cells and pericytes plays an important role in the maintenance of vascular integrity. Additionally, it has been suggested that pericytes have a contractile function. Platelet-derived growth factor (PDGF), released from endothelial cells, has been shown to be a potent mitogen and vasoconstrictor. Cytosolic free calcium ([Ca2+]i) has been shown to play a key role as a second messenger for PDGF, involved in the regulation of various cellular functions, e.g. cell proliferation and vascular contractility. In order to characterize the effect of different PDGF homodimers on cultured bovine retinal pericytes, we investigated PDGF-AA- and -BB-dependent alterations in [Ca2+]i was determined with the Ca(2+)-sensitive fluorescent probe Quin-2. Basal levels were 118 +/- 30 nM. Stimulation with PDGF-BB in concentrations ranging from 5 to 20 ng/ml led to a dose-dependent increase of [Ca2+]i with an EC50 of 5.8 ng/ml. Maximum stimulation, to about 280% of basal levels, occurred after 3-4 min. In contrast, PDGF-AA was not effective. The results suggest that PDGF-BB may influence the integrity and contractility of the retinal microvasculature via modulation of the intracellular calcium homeostasis of pericytes. Additionally, it can be speculated that cultured retinal pericytes express mainly PDGF-beta-type receptors.

No insurance, public insurance, and private insurance: do these options contribute to differences in general health?

This paper examines the validity of two of the basic assumptions made about health care insurance and health, namely that having any insurance is associated with better health and, in particular, that having public, welfare-based insurance has better health consequences for the poor than does having no insurance. These questions were addressed using data from the National Medical Expenditure Survey, a national household-based survey in 1987 of more than 36,000 people who were asked to report in detail about their medical care use and expenditures, health insurance coverage, and health and functional status. The results of the analysis indicate that being without insurance is associated with having poorer general health compared to persons with private insurance, and that the health of persons who qualify for public insurance is the poorest of any group--poorer even than those without insurance.

[Growth characteristics of bovine retinal pericytes in culture]

The loss of retinal pericytes is one of the earliest changes in diabetic retinopathy. In order to study this phenomenon in vitro, an optimal isolation and cultivation system has to be established. Therefore, pericytes from bovine retinae were isolated enzymatically with 0.4% collagenase in phosphate-buffered saline and identical immunologically by positive staining with antibodies against smooth muscle alpha-actin. Routine cultivation of pericytes was performed by using DMEM supplemented with 10% fetal calf serum. Dependent on the in vitro age of cells, the effect of the following reagents on proliferative activity was determined: fetal calf serum, heparin, ECGF, ECGF+heparin, and glucose. Increasing serum concentrations stimulated the proliferation of pericytes, although the degree of stimulation was reduced with increasing in vitro age. Heparin inhibited the growth in a dose-dependent manner; the achieving 50% inhibition was extrapolated to be 25 micrograms/ml. ECGF increased pericyte proliferation significantly, with a maximum at 10 microliters/ml. In addition, ECGF reversed the inhibitory effect of heparin. Furthermore, all tested glucose concentrations (5.5-27.75 mmol/l) did not show any influence on growth rates of pericytes. The results demonstrate that routine cultivation of retinal pericytes is possible. Moreover, they indicate that enhanced blood glucose concentrations, as observed in diabetic patients, are not the only important factor in the loss of retinal pericytes.

Health care utilization: the effect of extending insurance to adults on Medicaid or uninsured

Current health care system reform proposals center on reducing the number of uninsured by extending private health insurance coverage. Discussion has also included enrolling Medicaid recipients in private programs. Much of the deliberation concerning extending coverage has centered on cost, but largely has not addressed the implications for health care utilization by these groups. If private insurance is extended to those currently uninsured as well as the Medicaid population, what impact will it have on utilization? Using data from the 1987 National Medical Expenditure Survey, the results of this analysis show that utilization would increase for the uninsured if private insurance benefits were extended, whereas utilization would decrease for those with Medicaid, however, the magnitude of the increase depends on the type of care.

Nasal secretion of the ozone scavenger uric acid

Uric acid, an important scavenger of ozone, has been identified as the major low molecular weight antioxidant in baseline and cholinergically induced nasal secretions. The purpose of this study was to determine the specific tissue source of uric acid in airway secretions. The secretion of uric acid is increased by cholinergic stimulation and correlates closely with the secretion of lactoferrin (a nasal glandular protein), suggesting that submucosal glands are involved. Indeed, nasal turbinate tissue was found to contain uric acid. However, careful analysis of nasal turbinate tissue failed to reveal the presence of xanthine oxidase, the enzyme responsible for uric acid synthesis. These data suggest that uric acid might be taken up secondarily by glands from plasma. This possibility was strengthened by the observation that lowering the plasma urate level with probenecid concomitantly lowered urate secretion. These findings are consistent with the hypotheses that the principal source of uric acid in nasal secretions is plasma and that uric acid is taken up, concentrated, and secreted by nasal glands.