Training experience in drug and alcohol liaison work

We describe our training experience as members of a drug and alcohol liaison service within a major general teaching hospital. This type of liaison work offers valuable experience in the joint management of patients with well established substance misuse problems and also provides the opportunity for early recognition and preventative interventions.

Frailty and mortality in kidney transplant recipients

We have previously described strong associations between frailty, a measure of physiologic reserve initially described and validated in geriatrics, and early hospital readmission as well as delayed graft function. The goal of this study was to estimate its association with postkidney transplantation (post-KT) mortality. Frailty was prospectively measured in 537 KT recipients at the time of transplantation between November 2008 and August 2013. Cox proportional hazards models were adjusted for confounders using a novel approach to substantially improve model efficiency and generalizability in single-center studies. We precisely estimated the confounder coefficients using the large sample size of the Scientific Registry of Transplantation Recipients (n = 37 858) and introduced these into the single-center model, which then estimated the adjusted frailty coefficient. At 5 years, the survivals were 91.5%, 86.0% and 77.5% for nonfrail, intermediately frail and frail KT recipients, respectively. Frailty was independently associated with a 2.17-fold (95% CI: 1.01-4.65, p = 0.047) higher risk of death. In conclusion, regardless of age, frailty is a strong, independent risk factor for post-KT mortality, even after carefully adjusting for many confounders using a novel, efficient statistical approach.

Perceptions of community- and family-level injection drug user (IDU)- and HIV-related stigma, disclosure decisions and experiences with layered stigma among HIV-positive IDUs in Vietnam

This paper explores how perceived stigma and layered stigma related to injection drug use and being HIV-positive influence the decision to disclose one's HIV status to family and community and experiences with stigma following disclosure among a population of HIV-positive male injection drug users (IDUs) in Thai Nguyen, Vietnam. In qualitative interviews conducted between 2007 and 2008, 25 HIV-positive male IDUs described layered stigma in their community but an absence of layered stigma within their families. These findings suggest the importance of community-level HIV prevention interventions that counter stigma and support families caring for HIV-positive relatives.

Quantifying the hurdle concept by modelling the bacterial growth/no growth interface

The hurdle concept described eloquently over many years by Professor Leistner and his colleagues draws attention to the interaction of factors that affect microbial behaviour in foods. Under some circumstances these effects are additive. Under others the implication is that synergistic interactions lead to a combined effect of greater magnitude than the sum of constraints applied individually. Predictive modelling studies on the combined effects of temperature and water activity and temperature and pH suggest that the effect of these combinations on growth rate is independent. Where the effect of the two factors is interactive rather than independent is at the point where growth ceases--the growth/no growth interface. An interesting and consistent observation is that a very sharp cut off occurs between conditions permitting growth and those preventing growth, allowing those combinations of factors to be defined precisely and modelled. Growth/no growth interface models quantify the effects of various hurdles on the probability of growth and define combinations at which the growth rate is zero or the lag time infinite. Increasing the stringency of one or more hurdles at the interface by only a small amount will significantly decrease the probability of an organism growing. Understanding physiological processes occurring near the growth/no growth interface and changes induced by moving from one side of the interface to the other may well provide insights that can be exploited in a new generation of food preservation techniques with minimal impact on product quality.

Do not resuscitate (DNR): analysis of the DNR act

Due to advances in technology, physicians and patients are being faced with the issue of do not resuscitate (DNR). DNR is an order that determines whether or not cardiopulmonary resuscitation (CPR) should be administered to a critically ill person. Within the state of Oklahoma, the Oklahoma DNR act was created in order to establish regulations regarding the decision-making of when to use CPR. This Act gives rise to legal and ethical problems, which have been taken into consideration by the Oklahoma Association for Healthcare Ethics (OAHE). The following article focuses on DNR with examples of case histories and possible recommendations for improvement to the current law. Furthermore, this article sets out to show why the decision of whether or not to resuscitate should be made by the patient or their family.

Final report of Intergroup Trial 0122 (ECOG PE-289, RTOG 90-12): Phase II trial of neoadjuvant chemotherapy plus concurrent chemotherapy and high-dose radiation for squamous cell carcinoma of the esophagus

PURPOSE

To determine the outcome of neoadjuvant chemotherapy followed by concurrent chemotherapy plus high-dose radiation therapy in patients with local/regional squamous cell carcinoma of the esophagus.

METHODS AND MATERIALS

Forty-five patients with clinical Stage T1-4N0-1M0 squamous cell carcinoma were entered on a prospective single-arm study, of which 38 were eligible. Patients received 3 monthly cycles of 5-FU (1000 mg/m2/24 h x 5 days) and cisplatin (100 mg/m2 day 1; neoadjuvant segment) followed by 2 additional monthly cycles of 5-FU (1000 mg/m2/24 h x 5 days) and cisplatin (75 mg/m2 day 1) plus concurrent 6480 cGy (combined modality segment). The median follow-up in surviving patients was 59 months.

RESULTS

For the 38 eligible patients, the primary tumor response rate was 47% complete, 8% partial, and 3% stable disease. The first site of clinical failure was 39% local/regional and 24% distant. For the total patient group, there were 6 deaths during treatment, of which 9% (4/45) were treatment related. The median survival was 20 months. Actuarial survival at 3 years was 30%, and at 5 years, 20%.

CONCLUSION

This intensive neoadjuvant approach does not appear to offer a benefit compared with conventional doses and techniques of combined modality therapy. However, high dose radiation (6480 cGy) appears to be tolerable, and is being tested further in Intergroup Trial INT 0123.

N-Phenylamidines as selective inhibitors of human neuronal nitric oxide synthase: structure-activity studies and demonstration of in vivo activity

Selective inhibition of the neuronal isoform of nitric oxide synthase (NOS) compared to the endothelial and inducible isoforms may be required for treatment of neurological disorders caused by excessive production of nitric oxide. Recently, we described N-(3-(aminomethyl)benzyl)acetamidine (13) as a slow, tight-binding inhibitor, highly selective for human inducible nitric oxide synthase (iNOS). Removal of a single methylene bridge between the amidine nitrogen and phenyl ring to give N-(3-(aminomethyl)phenyl)acetamidine (14) dramatically altered the selectivity to give a neuronal selective nitric oxide synthase (nNOS) inhibitor. Part of this large shift in selectivity was due to 14 being a rapidly reversible inhibitor of iNOS in contrast to the essentially irreversible inhibition of iNOS observed with 13. Structure-activity studies revealed that a basic amine functionality tethered to an aromatic ring and a sterically compact amidine are key pharmacophores for this class of NOS inhibitors. Maximal nNOS inhibition potency was achieved with N-(3-(aminomethyl)phenyl)-2-furanylamidine (77) (Ki-nNOS = 0.006 microM; Ki-eNOS = 0.35 microM; Ki-iNOS = 0.16 microM). Finally, alpha-fluoro-N-(3-(aminomethyl)phenyl)acetamidine (74) (Ki-nNOS = 0. 011 microM; Ki-eNOS = 1.1 microM; Ki-iNOS = 0.48 microM) had excellent brain penetration and inhibited nNOS in a rat brain slice assay as well as in the rat brain (cerebellum) in vivo. Thus, N-phenylamidines should be useful in validating the role of nNOS in neurological disorders.

Sucralfate for radiation mucositis: results of a double-blind randomized trial

PURPOSE

To determine if addition of the ulcer-coating polysaccharide sucralfate could improve symptomatic relief of radiation mucositis over a popular combination of antacid, diphenhydramine, and viscous lidocaine alone.

METHODS AND MATERIALS

A double-blind study was conducted in which nurses and pharmacists coded patient groups and distributed medication in a manner blinded to both the patients and physicians. Eligible patients receiving radiation to the head and neck and/or chest sites that included the esophagus were randomized to a standard combination of antacid, diphenhydramine, and viscous lidocaine vs. the same solution plus sucralfate. Eligible patients were those receiving >40 Gy at 1.8 Gy/fraction, one fraction/day, five fractions/week. Participating patients were stratified between chest, small field head and neck, and large field head and neck. The patients subjective evaluation of throat soreness and relief with medication was elicited as well as physician observations and smears for Candidiasis screening. Medication was prescribed when the patient became symptomatic and concomitant use of other locally effective nonstudy agents was not allowed. The ability to eat various consistency of foods was graded 0-5, with 5 indicating no compromise of ability to ingest a food compared to baseline. Statistical analysis included mean + SD for food and soreness scores, paired t-test, and two-way analyses of variance to evaluate effects of site and treatment group on the changes in scores.

RESULTS

Over 2 years, 111 patients were entered. Because some withdrew and others did not require medication, results are presented for evaluable patients in each category. Mild adverse effects from the medication solution (usually mouth discomfort) were reported by <10% of patients in each treatment group among 106 patients evaluable for toxicity. There was a comparable incidence of mild-moderate mucositis for the two treatment groups. Severe mucositis was noted in two patients of the standard medication group and none among patients receiving sucralfate. The groups were comparable for indicators including degree of soreness, dietary changes, and objective measures or mucosal irritation or infection. For the head and neck patients there was a significant worsening in soreness and in the ability to eat in both treatment groups, whereas patients treated to the chest had less nutritional change. Multivariate analysis including control for confounding factors did not detect treatment effects for any of the response measures. No patient had occult fungal infection detected by oral pathology evaluation of routine mucosal scrapings.

CONCLUSIONS

A trend (that was not statistically significant) of less severe radiation mucositis was noted for patients receiving sucralfate in addition to the combination of viscous lidocaine, diphenhydramine, and antacid for nonulcerative radiation mucositis.

Quantitative microbiology: a basis for food safety

Because microorganisms are easily dispersed, display physiologic diversity, and tolerate extreme conditions, they are ubiquitous and may contaminate and grow in many food products. The behavior of microbial populations in foods (growth, survival, or death) is determined by the properties of the food (e.g., water activity and pH) and the storage conditions (e.g., temperature, relative humidity, and atmosphere). The effect of these properties can be predicted by mathematical models derived from quantitative studies on microbial populations. Temperature abuse is a major factor contributing to foodborne disease; monitoring temperature history during food processing, distribution, and storage is a simple, effective means to reduce the incidence of food poisoning. Interpretation of temperature profiles by computer programs based on predictive models allows informed decisions on the shelf life and safety of foods. In- or on-package temperature indicators require further development to accurately predict microbial behavior. We suggest a basis for a "universal" temperature indicator. This article emphasizes the need to combine kinetic and probability approaches to modeling and suggests a method to define the bacterial growth/no growth interface. Advances in controlling foodborne pathogens depend on understanding the pathogens' physiologic responses to growth constraints, including constraints conferring increased survival capacity.

Determination of the flux control coefficient of nitric oxide synthase for nitric oxide synthesis in discrete brain regions in vivo

The flux control coefficient of nitric oxide synthase (NOS), for the in vivo synthesis of the key biological mediator nitric oxide (NO), was determined in four rat brain regions with varying NOS activities (cerebral cortex, hippocampus, amygdala and cerebellum) using metabolic control theory. Flux control coefficients were calculated from the ratio of the initial slopes of the fractional effect of the NOS inhibitor N omega-nitro-L-arginine (L-NA) on NO pathway flux and NOS activity. Under conditions of normal behaviour in the rat, NOS had a flux control coefficient not significantly different from one in all regions examined. These data demonstrate that the large majority of flux control for the synthesis of NO in the brain resides in NOS itself and not in the transport of its amino acid precursor, L-arginine, across the blood-brain or neuronal cell membranes. This paper describes the first example in which the control of metabolic flux has been quantified in a mammalian system in vivo and demonstrates the power of metabolic control theory to elucidate the distribution of control within a metabolic pathway in vivo.

The nitric oxide-cyclic GMP pathway is required for nociceptive signalling at specific loci within the somatosensory pathway

The involvement of nitric oxide in nociceptive processing was examined at the main loci of synaptic transmission within the rat somatosensory pathway from the caudal sural cutaneous nerve. Intrathecal (lumbar 1-3) administration of the nitric oxide synthase inhibitor, N omega-nitro-L-arginine methyl ester (30 micrograms), inhibited nitric oxide synthase in this region of the spinal cord by greater than 80% but had no significant effect on nitric oxide synthase in parietal cerebral cortex, thalamus or medulla/pons. In a rat model of peripheral neuropathy (one to two week ligation of the caudal sural cutaneous nerve), intrathecal administration of the same dose of N omega-nitro-L-arginine methyl ester prevented the hyperalgesic response to thermal stimuli. Administration of 30 micrograms N omega-nitro-L-arginine methyl ester into the lateral ventricle had no effect on nitric oxide synthase in the lumbar 1-3 region of the spinal cord but gave substantial inhibition in higher areas of the somatosensory pathway (parietal cerebral cortex, thalamus and medulla/pons). Nitric oxide synthase in the parietal cerebral cortex (but not thalamus) was inhibited to a greater extent in the hemisphere ipsilateral to the site of administration. Administration of 30 micrograms N omega-nitro-L-arginine methyl ester into the lateral ventricle decreased thermal hyperalgesia, but only when N omega-nitro-L-arginine methyl ester was administered contralateral to the ligated caudal sural cutaneous nerve and therefore ipsilateral to the cortical nociceptive processing from this nerve. Intrathecal and intracerebroventricular administration of the selective inhibitor of nitric oxide-sensitive guanylyl cyclase, 1-H-[1,2,4]oxadiazalo[4,3-a]quinoxalin-1-one, also decreased the hyperalgesic response to thermal stimuli. These data demonstrate that, in a model of neuropathic pain, nitric oxide is involved in nociceptive processing at spinal and cerebrocortical synaptic loci of the somatosensory pathway and that its actions appear to be mediated through guanylyl cyclase.

Ex vivo measurement of brain tissue nitrite and nitrate accurately reflects nitric oxide synthase activity in vivo

The ex vivo tissue concentration of nitrite and nitrate (NOx) was found to correlate closely with the activity of nitric oxide synthase (NOS; EC 1.14.13.39) in various brain regions. Systemic administration of the nonselective NOS inhibitor N omega-nitro-L-arginine (L-NA) at doses that completely inhibited both central and peripheral NOS, depleted whole-brain and CSF NOx by up to 75% but had no effect on plasma NOx. Selective inhibition of central NOS by intracerebroventricular administration of L-NA methyl ester produced similar decreases in levels of whole-brain NOx. A residual concentration of NOx of 10-15 microM remained in all brain regions even after complete inhibition of brain NOS. Brain NOx content decreased rapidly and in parallel with the inhibition of brain NOS. The ex vivo measurement of levels of brain NOx was found to reflect the in vivo efficacy of several different types of NOS inhibitor: L-NA, N omega-monomethyl-l-arginine, and 7-nitroindazole. Intraperitoneal administration of the NOS substrate L-arginine increased brain NOx concentrations by up to 150% of control values. These results demonstrate that the ex vivo measurement of levels of brain tissue NOx is a rapid, reliable, and straightforward technique to determine NOS activity in vivo. This method can be used to assess both the regional distribution and the degree of inhibition of NOS activity in vivo.

Management of substance misusers on the general hospital ward

Since a high prevalence of physical morbidity is associated with substance misuse, drug misusers are frequently admitted to general hospitals. Medical staff often perceive drug misusers as a particularly difficult patient group, feeling that they lack the knowledge and skill to deal with them adequately without specialist support. We review the common physical complications of substance misuse likely to be encountered in a general hospital, and provide comprehensive guidelines for the assessment and management of drug dependence in this setting.

A phase III randomized prospective trial of external beam radiotherapy, mitomycin C, carmustine, and 6-mercaptopurine for the treatment of adults with anaplastic glioma of the brain. CNS Cancer Consortium

PURPOSE

This study was designed to evaluate strategies to overcome the resistance of anaplastic gliomas of the brain to external beam radiotherapy (ERT) plus carmustine (BCNU). Patients were > or = 15 years of age, had a histologic diagnosis of malignant glioma, and a Karnofsky performance status (KPS) > or = 60%.

METHODS AND MATERIALS

In Randomization 1, patients were assigned to receive either ERT alone (61.2 Gy) or ERT plus mitomycin C (Mito, IV 12.5 mg/m(2)) during the first and fourth week of ERT. After this treatment, patients went on to Randomization 2, where they were assigned to receive either BCNU (i.v. 200 mg/m(2)) given at 6-week intervals or 6-mercaptopurine (6- MP, 750 mg/m(2) IV daily for 3 days every six weeks), with BCNU given on the third day of the 6-MP treatment. Three hundred twenty-seven patients underwent Randomization 1. One hundred sixty-four received ERT alone, and 163 received ERT + Mito [average 52.7 years; 63% male; 69% glioblastoma multiforme (GBM); 66% had a resection; 56% KPS > or = 90%]. Step-wise analysis of survival from Randomization 1 or 2 indicates that survival was significantly diminished by: (a) age > or = 45 years (b) KPS < 90%; (c) GBM/gliosarcoma histology; (d) stereotactic biopsy as opposed to open biopsy or resection. Median survival from Randomization 1 in both arms (ERT + Mito) was 10.8 months. Median survival from Randomization 2 was 9.3 months for BCNU/6MP vs. 11.4 months for the BCNU group (p = 0.35). Carmustine/6-MP showed a possible survival benefit for histologies other than GBM/GS. Two hundred and thirty-three patients underwent Randomization 2. The proportion of patients in the ERT group who terminated study prior to Randomization 2 was significantly less in the ERT group than in the ERT + Mito group (20 vs. 37%, p < 0.001).

CONCLUSIONS

(a) The addition of Mito to ERT had no impact on survival; (b) patients treated with ERT + Mito were at greater risk of terminating therapy prior to Randomization 2; (c) there was not a significant survival benefit to the addition of 6-MP to BCNU.

Effects of 540C91 [(E)-3-[2-(4'-pyridyl)-vinyl]-1H-indole], an inhibitor of hepatic tryptophan dioxygenase, on brain quinolinic acid in mice

Studies were undertaken to assess the role of the liver in the formation of the neurotoxin quinolinic acid in the brain. A selective and potent inhibitor of hepatic tryptophan 2,3-dioxygenase, 540C91 [(E)-3-[2-(4'-pyridyl)-vinyl]-1H-indole], largely prevented the elevation in mouse brain quinolinic acid resulting from parenteral injection of tryptophan (TRP). In contrast, 540C91 did not affect basal levels of the neurotoxin. Following induction of indoleamine dioxygenase with bacterial lipopolysaccharide, 540C91 was less effective in preventing the TRP-induced elevations in quinolinic acid. The data suggest that kynurenines, formed from tryptophan, by the liver and other extrahepatic organs can give rise to brain quinolinic acid.

Substantial regional and hemispheric differences in brain nitric oxide synthase (NOS) inhibition following intracerebroventricular administration of N omega-nitro-L-arginine (L-NA) and its methyl ester (L-NAME)

Nitric oxide synthase (NOS) enzyme activity was determined in a comprehensive selection of regions of the rat brain. The effects of lateral ventricular administration of N omega-nitro-L-arginine (L-NA, 30 micrograms) and its methyl ester (L-NAME, 3-100 micrograms) on NOS activity were examined in the ipsilateral and contralateral areas of 4 of these brain regions and in the cerebellum. NOS activity was determined using a new and rapid ex vivo assay method which ensures minimal dissociation of the enzyme-inhibitor complex. Following infusion of L-NAME, NOS activity was rapidly and dose-dependently inhibited in all brain regions studied (cerebral cortex, striatum, hippocampus, cerebellum and thalamus). However, NOS activity of brain regions within the contralateral hemisphere was inhibited significantly less than in ipsilateral regions, with the exception of the thalamus. The degree of NOS inhibition varied markedly between brain regions within each hemisphere and correlated with their ventricular proximity to the site of NOS inhibitor administration. Therefore, NOS in the thalamus was inhibited most effectively and NOS in the cerebral cortex the least. Within the cerebral cortex further regional differences could be observed, with NOS in the frontal/parietal areas inhibited more effectively than NOS in the temporal/occipital areas. Maximal inhibition of NOS was sustained for approx 6 hr after administration of 30 and 100 micrograms L-NAME. No inhibition of NOS was observed 24 hr after administration. Lateral ventricular administration of the metabolite and active moiety of L-NAME, L-NA, resulted in a similar degree of inhibition and time of inhibitory onset. In contrast, when L-NAME was administered i.p., a significant delay in the onset of NOS inhibition was observed in the above brain regions compared to L-NA. However, no regional or hemispheric differences in NOS inhibition were detected following peripheral administration of these inhibitors. These results indicate that central administration of NOS inhibitors yields a complex pattern of NOS inhibition and that data obtained on brain physiology following the i.c.v. administration of NOS inhibitors, or for that matter any other CNS effector, should therefore be interpreted with extreme caution.

The effects of a novel and selective inhibitor of tryptophan 2,3-dioxygenase on tryptophan and serotonin metabolism in the rat

The effects of a novel inhibitor 680C91 ((E)-6-fluoro-3-[2-(3- pyridyl)vinyl]-1H-indole) of the key enzyme of tryptophan catabolism tryptophan 2,3-dioxygenase (TDO) (EC 1.13.11.11), were examined on tryptophan catabolism in vitro and in vivo and on brain levels of tryptophan, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA). 680C91 was a potent (Ki = 51 nM) and selective TDO inhibitor with no inhibitory activity against indoleamine 2,3-dioxygenase (EC 1.13.11.17), monoamine oxidase A and B, 5-HT uptake and 5-HT1A,1D,2A and 2C receptors at a concentration of 10 microM. 680C91 had no effect on the binding of tryptophan to serum albumin in plasma and inhibited TDO competitively with respect to its substrate tryptophan. 680C91 inhibited the catabolism of tryptophan by rat liver cells and rat liver perfused in situ. The catabolism of L-[ring-2-14C]-tryptophan and a load dose of tryptophan (100 mg/kg) in vivo were inhibited by prior administration of 680C91. Administration of 680C91 alone produced marked increases in brain tryptophan, 5-HT and 5-HIAA. A load dose of tryptophan (100 mg/kg), producing increases in brain tryptophan 4-fold greater than that seen with 680C91, did not increase brain 5-HT and 5-HIAA to levels greater than those seen with 680C91 and produced a shorter-lasting increase in these parameters. These data therefore demonstrate the importance of TDO as a regulator of whole-body tryptophan catabolism and brain levels of tryptophan and 5-HT and suggest that a greater antidepressant efficacy might be achieved with inhibitors of TDO than tryptophan administration alone.

Determination of brain nitric oxide synthase inhibition in vivo: ex vivo assays of nitric oxide synthase can give incorrect results

The in vivo potencies of N omega-nitro-L-arginine (L-NA), N omega-monomethyl-L-arginine (L-NMMA) and N omega-iminoethyl-L-ornithine (L-NIO) against brain nitric oxide synthase (NOS) were determined by assessing their ability to inhibit harmaline-induced increases in rat cerebellar cGMP. L-NA, L-NIO and L-NMMA were all able to completely prevent the harmaline-induced increase in cGMP with ID50s of 0.5, 30 and 55 mg/kg, respectively, and with the same order of potency as that seen for inhibition of cerebellar NOS in vitro. The inhibitory effects of low doses of L-NA on cerebellar cGMP were maintained for at least 8 hr. The ID50 of L-NA for inhibition of cerebellar cGMP in vivo was similar to its ID50 for inhibition of cerebellar NOS ex vivo but only when NOS activity was assayed as an initial rate. However, doses of L-NMMA and L-NIO that inhibited harmaline-induced increases in cerebellar cGMP in vivo by 50% failed to inhibit NOS ex vivo. The methyl ester of L-NA, L-NAME, produced substantial inhibition of cerebellar NOS ex vivo when given either orally, intraperitoneally or intravenously but with a slower onset of action than L-NA. These results demonstrate that measurement of NOS activity ex vivo can accurately reflect the degree of inhibition of NOS in vivo with inhibitors that dissociate slowly from the enzyme such as L-NA, but only when the initial rate of NOS activity is measured.

The effects of an inhibitor of tryptophan 2,3-dioxygenase and a combined inhibitor of tryptophan 2,3-dioxygenase and 5-HT reuptake in the rat

The effects of a novel inhibitor 680C91 ((E)-6-fluoro-3-[2-(3-pyridyl)vinyl]-1H-indole) of the key enzyme of tryptophan catabolism tryptophan 2,3-dioxygenase (TDO), and a novel inhibitor 709W92 ((E)-6-fluoro-3-[2-(4-pyridyl)vinyl]-1H-indole), of both TDO and 5-hydroxytryptamine (5-HT) reuptake, were examined on tryptophan catabolism, cerebrospinal fluid (CSF) concentrations of tryptophan and 5-HT and serotonergic-mediated physiology and behaviour in the rat. The catabolism of L-[ring-2-14C]tryptophan in vivo was completely inhibited by prior administration of 709W92. 709W92, but not 680C91, potentiated head-twitch produced by 5-hydroxytryptophan, prevented head-twitch and whole brain 5-HT depletion produced by p-chloroamphetamine and rapidly decreased dorsal raphe firing. Both 709W92 and 680C91 elevated CSF tryptophan by up to 260% of basal concentration. A maximally effective dose of 680C91 elevated a global measure of brain extracellular 5-HT (CSF 5-HT) to concentrations similar to those seen maximally after exogenous tryptophan administration (approx 170% of basal). Maximally effective doses of 709W92 increased CSF 5-HT to concentrations comparable to those seen after tryptophan and 5-HT reuptake inhibitor coadministration (approx 900% of basal) and to concentrations greater than those achieved maximally with serotonergically active antidepressant monotherapy (approx 500% of basal). 709W92 did not elevate CSF 5-HT to concentrations associated with the serotonin syndrome (approx 3000% of basal). The combined TDO inhibitor/5-HT reuptake inhibitor, 709W92, showed anxiolytic activity in the rat-pup vocalization model of anxiety. These results show that 709W92 (a novel inhibitor of both TDO and 5-HT reuptake), can produce an elevation of CSF 5-HT similar to that achieved with a serotonin reuptake inhibitor/tryptophan combination therapy but with a more sustained timecourse; such compounds may therefore have superior antidepressant efficacy in the clinic.

Potent and selective inhibition of human nitric oxide synthases. Selective inhibition of neuronal nitric oxide synthase by S-methyl-L-thiocitrulline and S-ethyl-L-thiocitrulline

Potent and selective inhibition of neuronal nitric oxide synthase (nNOS) compared to endothelial NOS (eNOS) and inducible NOS (iNOS) may be useful to treat cerebral ischemia (stroke) and other neurodegenerative diseases. S-Methyl-L-thiocitrulline (Me-TC) and S-ethyl-L-thiocitrulline (Et-TC) inhibited the oxidation of L-arginine and the L-arginine-independent oxidation of NADPH by nNOS from human brain. Me-TC and Et-TC were slow, tight binding inhibitors of nNOS with second-order association rate constants (kon) of 2.6 x 10(5) M-1 s-1 and 1.3 x 10(5) M-1 s-1, respectively. The respective dissociation rate constants (koff) were 3 x 10(-4) s-1 and 0.7 x 10(-4) s-1. Thus, the Kd values calculated from koff/kon were 1.2 and 0.5 nM, respectively. L-Arginine was a competitive inhibitor of Me-TC and Et-TC binding with competition constant (Ks) values of 2.2 and 2.7 microM, respectively. The Km of nNOS for L-arginine was 1.6 microM. The active site concentration of nNOS was estimated by titration with Et-TC. Based on this active site concentration, a kcat of 0.4 s-1 for the oxidation of L-arginine, was calculated. Me-TC and Et-TC were less potent inhibitors of human iNOS (Ki values of 34 and 17 nM, respectively) and human eNOS (Ki values of 11 and 24 nM). Thus, Me-TC and Et-TC were 10- and 50-fold, respectively, more potent inhibitors of nNOS than eNOS. Furthermore, Me-TC was also 17-fold selective for rat nNOS in neuronal tissue compared to rat eNOS in vascular endothelium, suggesting that Me-TC may be selective for nNOS in vivo and therefore, may be therapeutically useful to treat neurodegenerative diseases.

A quantitative analysis of the control of glutamine catabolism in rat liver cells. Use of selective inhibitors

1. At a physiological concentration of glutamine (0.5 mM), 87% of the total transport across the plasma membrane of liver cells isolated from fed rats involved the Na(+)-dependent system N; this was substantially inhibited by L-histidine. The residual Na(+)-independent component was attributed to system L on the basis of inhibition by 2-amino-2-norbornanecarboxylate and L-tryptophan. 2. Catabolism of glutamine by intact liver cells or by isolated mitochondria was inhibited by glutamate gamma-hydrazide with IC50 values of 13.7 +/- 3.5 microM and 22.6 +/- 3.8 microM respectively and a maximal inhibition of approx. 75%. The site of inhibition was identified as glutaminase; glutamate gamma-hydrazide inhibited this enzyme in cell-free extracts (IC50 37.8 +/- 7.7 microM) but had no activity against glutamate dehydrogenase or transport of glutamine, whether across mitochondrial or plasma membranes. 3. The major control site in cells from fed animals incubated with 0.5 mM L-glutamine was glutaminase (flux control coefficient 0.96). Appreciable control also resided in both plasma membrane transport systems, with coefficients of 0.51 for system N and -0.46 for system L, such that both interacted to provide a fine control of the intracellular concentration of the amino acid. Similar values were obtained by computer simulation based on theoretical determination of elasticities. 4. Previous controversy about the locus of regulation of hepatic glutamine metabolism is resolved by this distribution of control.

An analysis of radiotherapy data from the CNS cancer consortium's randomized prospective trial comparing AZQ to BCNU in the treatment of patients with primary malignant brain tumors. The CNS cancer consortium

The CNS Cancer Consortium has conducted a phase III study comparing diaziquone (AZQ) with carmustine (BCNU) in the treatment of adults with primary anaplastic glial brain tumors. Patients eligible for this study were 18 years of age or older at the time of biopsy, subtotal resection, or gross total resection of an anaplastic glial brain tumor. Within 3 weeks of surgery, patients received whole brain radiotherapy at 1.7 to 2 Gy per fraction to a total whole brain dose of 42-48 Gy. This was followed by a boost to the tumor bed as ascertained by computed tomography (CT), angiography, and/or magnetic resonance imaging (MRI) of 1.7 to 2 Gy per fraction to a dose of 12-19 Gy. The recommended cumulative dose to the tumor bed was therefore 55-61 Gy. At 8 weeks following radiotherapy, patients were randomized to receive either AZQ at 15 mg/day for 3 days i.v. every 4 weeks or BCNU at 200 mg i.v. every 8 weeks. Chemotherapy was continued for at least 1 year unless death occurred, treatment failure was declared, or toxicity necessitated alteration of therapy. In the 249 randomized patients, there was no difference between the AZQ- and BCNU-treated patients in age, sex distribution, race, tumor histology, type of surgical resection, or Karnofsky performance status (KPS). Age and KPS at the initiation of therapy and tumor histology were the best overall predictors of survival. The type of chemotherapy (AZQ vs BCNU) was not predictive of survival. Two-year Kaplan-Meier survival was 22% in the AZQ-treated patients and 25% in BCNU-treated patients. In an analysis of radiotherapy administered we found that, within the range of doses required for this study, there was no influence of whole brain dose, boost dose, total dose, or size of the boost field on survival. The institution providing radiotherapy (teaching hospital vs nonteaching facility) did not influence survival.

Uptake of acetaminophen (paracetamol) by isolated rat liver cells

The characteristics of the uptake of acetaminophen (N-acetyl-p-aminophenol or paracetamol, APAP) in incubations of isolated rat liver cells were consistent with diffusion of the drug being the predominant mechanism of APAP influx in these cells at concentrations above 0.5 mM. At lower substrate concentrations (below 0.5 mM) a saturable component was apparent. Both uptake processes could have a role in the control of the metabolism of APAP, because, at low concentrations, there was no intracellular accumulation of unconjugated drug, all the APAP entering the cell being converted to sulphate and glucuronide. After addition of drug, there was a lag phase of approximately 5 min before APAP-glucuronide and APAP-sulphate appeared in the incubation medium; during this time both conjugates accumulated inside the cells. These results have implications for our understanding of the mechanisms of APAP transport, and indicate how these processes may affect the drug's overall metabolism.

Widespread tissue distribution, species distribution and changes in activity of Ca(2+)-dependent and Ca(2+)-independent nitric oxide synthases

The distribution of Ca(2+)-dependent and Ca(2+)-independent nitric oxide synthase (NOS) was studied in rabbits and in control and endotoxin-treated rats and guinea-pigs. There was a widespread localization of NOS which differed for the two forms of the enzyme and which showed marked differences between species. Endotoxin induced the activity of the Ca(2+)-independent NOS in many tissues and also increased the activity of Ca(2+)-dependent NOS in the rat ileum and caecum. These results demonstrate the differential distribution of NOSs in control and endotoxin-treated animals and emphasize the widespread biological role of nitric oxide (NO).

A possible novel pathway of regulation by murine T helper type-2 (Th2) cells of a Th1 cell activity via the modulation of the induction of nitric oxide synthase on macrophages

Murine peritoneal macrophages activated with interferon (IFN)-gamma and lipopolysaccharide (LPS) produce high levels of nitric oxide (NO) and are efficient in killing the intracellular protozoan parasites Leishmania major in vitro. Earlier studies have shown that NO, whose synthesis in murine macrophages is catalyzed by an inducible enzyme NO synthase, plays a major effector role in the host resistance against microbial infection. We now shown that both the NO synthesis and the leishmanicidal activity can be inhibited by prior treatment of the cells with recombinant interleukin 4 (IL4). IL4 treatment had no effect on the binding of IFN-gamma to macrophages but prevented the induction of NO synthase in these cells activated with IFN-gamma and LPS. Since IFN-gamma is produced by murine T helper type-1 (Th1) cells, whereas IL4 is secreted by Th2 cells, these results suggest a novel pathway by which Th2 cells regulate an activity of Th1 cells, namely by inhibiting the induction of NO synthase. These results may also account for the mechanism by which the disease-promoting Th2 cells counteract the host-protective effect of Th1 cells in leishmaniasis and other intracellular parasitic diseases.

Parents' worries about children compared to actual risks

To investigate the concerns of parents, questionnaires were given to the "first 100" parents waiting for their child's pediatric appointment in four different medical settings. They were asked to rate whether they worry "frequently," "occasionally," or "not at all" about 17 physical health issues, 16 psychosocial problems, 7 possible injuries, 4 instances of victimization, and 4 questions about parents' ability to provide discipline, affection, values and financial support. The response rate was 94%; 89% were completed adequately for analysis. Parental concerns were compared to data from the National Center for Health Statistics about the statistical likelihood of the risks occurring. Ear infections (65%) were the most common health concern, followed by reaction to immunization (57%), common colds (51%), and cancer (50%). The greatest psychosocial concern was about children watching too much television (53%), followed by concerns about the quality of day care (50%). Three-quarters of parents worry about car accidents and 72% worry about abduction of their children. Parents worry significantly about their own contribution to their child's welfare: appropriate discipline (73%), affection (56%), values and being a role model (55%), and financial support (66%). Parents who had not completed high school worried more than parents who had more than a high school education (P less than 0.03).