Osteochondritis dissecans (OCD), an endoplasmic reticulum storage disease?: a morphological and molecular study of OCD fragments.

Osteochondritis dissecans (OCD) fragments, cartilage and blood from four patients were used for morphological and molecular analysis. Controls included articular cartilage and blood samples from healthy individuals. Light microscopy and transmission electron microscopy (TEM) showed abnormalities in chondrocytes and extracellular matrix of cartilage from OCD patients. Abnormal type II collagen heterofibrils in "bundles" and chondrocytes with abnormal accumulation of matrix proteins in distended rough endoplasmic reticulum were typical findings. Further, Von Kossa staining and TEM showed empty lacunae close to mineralized "islands" in the cartilage and hypertrophic chondrocytes containing accumulated matrix proteins. Immunostaining revealed: (1) that types I, II, VI and X collagens and aggrecans were deposited intracellulary and (2) co-localization within the islands of types I, II, X collagens and aggrecan indicating that hypertrophic chondrocytes express a phenotype of bone cells during endochondral ossification. Types I, VI and X collagens were also present across the entire dissecates suggesting that chondrocytes were dedifferentiated. DNA sequencings were non-conclusive, only single nucleotide polymorphism was found within the COL2A1 gene for one patient. We suggest that OCD lesions are caused by an alteration in chondrocyte matrix synthesis causing an endoplasmic reticulum storage disease phenotype, which disturbs or abrupts endochondral ossification.

Bone health and fracture rate in individuals with neurofibromatosis 1 (NF1).

BACKGROUND: Patients with neurofibromatosis 1 (NF1) are shorter than expected and often have low bone mineral density (BMD), but the pathogenesis of these bony problems is poorly understood. METHODS: We performed an exploratory study of BMD, 18 laboratory measures of bone metabolism, and fracture history in 72 adult NF1 patients. RESULTS: Eight of the 18 clinical biochemical measures of bone health had at least 10% of NF1 patients outside the standard reference range. Serum 25-hydroxy-vitamin D concentrations were low in 56% of the NF1 patients, serum parathyroid hormone (PTH) concentrations were high in 34%, and urine deoxypyridinoline cross-link concentrations were high in 50%. Mean serum 25-hydroxy-vitamin D concentrations were significantly lower in people with NF1 than in season matched controls in both summer (p = 0.008) and winter (p<0.001). 36 (50%) of the 72 people with NF1 studied had BMD consistent with osteopenia, and 14 (19%) had BMD consistent with osteoporosis. High serum PTH concentration, high serum bone tartrate resistant acid phosphatase concentration, and high serum calcium concentration were associated with lower BMD among the NF1 patients. Males were more likely than females to have low BMD. The reported frequency of fractures in individuals with NF1 was much higher than in their unaffected siblings and spouses (p<0.001), and pathological fractures were reported only in NF1 patients. CONCLUSION: People with NF1 often have a generalised abnormality of bone metabolism. Further studies are needed to determine the biochemical and molecular basis of this abnormality.

Antimicrobial resistance in Campylobacter jejuni from broilers and broiler house environments in Norway.

Antimicrobial susceptibility in Campylobacter jejuni collected from the environment outside four broiler houses (n = 63) and from the environment inside these broiler houses (including broiler droppings) (n = 36) from May to September 2004 was studied and compared with isolates from Norwegian broilers analyzed within the frame of the Norwegian monitoring program of antimicrobial resistance in feed, food, and animals (NORM-VET) in 2004 (n = 75). The MICs of oxytetracycline, ampicillin, erythromycin, gentamicin, enrofloxacin, and nalidixic acid were obtained by the broth microdilution method VetMIC. The present study, which to our knowledge is the first Norwegian study on the occurrence of antimicrobial resistance in Campylobacter spp. from the environment of broiler houses, revealed a very low occurrence of antimicrobial resistance in C. jejuni from the broilers and broiler house environments studied. All isolates originating from the four broiler houses studied were susceptible to all the antimicrobial agents tested, except for one isolate from the outdoor environment (courtyard soil), which was resistant to oxytetracycline (MIC, 8 mg/liter). For the isolates from broilers (NORM-VET), low prevalences of resistance to oxytetracycline (1.3%) and ampicillin (4%) were observed. No quinolone resistance was observed. The results for the broiler isolates are in agreement with the earlier findings of a very low prevalence of resistance in Campylobacter from broilers in Norway, which reflects the low usage of antimicrobials in Norwegian broiler production. Furthermore, the present data are in accordance with antimicrobial susceptibility data for C. jejuni from domestically acquired human cases.

Genotyping of Campylobacter jejuni from broiler carcasses and slaughterhouse environment by amplified fragment length polymorphism.

We examined the occurrence and diversity of Campylobacter jejuni on broiler carcasses during slaughter of an infected flock and in the slaughterhouse environment during slaughter and postdisinfection before a new production run. During the slaughter of a known C. jejuni infected broiler flock, samples were taken from broiler carcasses at 7 different stages during the process. Thirty-seven sites in the slaughterhouse environment were sampled both during process and postdisinfection. The samples were analyzed for C. jejuni, and genetic fingerprinting was performed using amplified fragment length polymorphism. All carcass samples were positive. Of the environmental samples collected during slaughter, 89% were positive; 100% of those from the arrival, stunning, scalding, defeathering, and evisceration facilities and 67% of those from the cooling and sorting facilities. Postdisinfection, 41% of the samples were positive; 71% of those from the arrival and stunning area, 60% of those from the scalding and defeathering area, and 20% of those from the evisceration, cooling, and sorting area. The C. jejuni isolates (n = 60) recovered were grouped into 4 different amplified fragment length polymorphism clones with a similarity index of 95% or greater. All isolates obtained from the flock and 94% of the isolates obtained from the environment during slaughtering belonged to clone A, whereas 1 environmental isolate belonged to each of the clones B and C. Isolates from clones A, B, and D were present postdisinfection. Only clone B was detected on flocks slaughtered during the previous week. The high level and continuous presence of Campylobacter in the environment constitutes a risk for transmission to negative carcasses. In Norway, where above 96% of the broiler flocks are Campylobacter-negative, this aspect is of special importance. The ability of Campylobacter to remain in the slaughterhouse environment through washing and disinfection is associated with constructional conditions of equipment and buildings, complicating cleaning and providing sufficient moisture. To reduce the probability of the workers acquiring campylobacteriosis, precautions should be taken when slaughtering Campylobacter-positive flocks.

Results of a pilot antibiotic resistance survey of Albanian poultry farms.

Global dissemination of antibiotic-resistant bacteria in food animals is a major public health concern. Whilst many countries have implemented prudent antibiotic use policies and surveillance systems both in clinical and veterinary settings, there are no such systems in place in Albania and little is known about the levels of antibiotic-resistant bacteria in food animals within the country. A total of 172 poultry samples were taken from six Albanian farms over a 3-month period and were tested for the presence of Enterobacteriaceae. In total, 91 bacterial isolates were obtained and were characterised by species (Escherichia coli, Salmonella spp. or other Enterobacteriaceae) and by susceptibility to 11 antibiotics. Resistance rates of E. coli and Salmonella isolates were, respectively: amoxicillin (86%, 64%); chloramphenicol (77%, 82%); ciprofloxacin (93%, 73%); cefotaxime (14%, 0%); gentamicin (12%, 0%); kanamycin (30%, 18%); nalidixic acid (91%, 73%); streptomycin (70%, 55%); sulphonamides (91%, 73%); tetracycline (95%, 73%); and trimethoprim (79%, 64%). Multidrug resistance to at least four antibiotics was observed in 95% of E. coli isolates and 82% of Salmonella. In conclusion, these data indicate that: (i) Salmonella and E. coli isolates from Albanian poultry farms exhibit high to extremely high levels of antibiotic resistance; (ii) Salmonella and E. coli isolates exhibit resistance to multiple antibiotics; and (iii) multidrug resistance profiles among Enterobacteriaceae are geographically widespread. Implementation of prudent antibiotic use policies in food animals and related surveillance will be necessary to reduce the emergence, spread and establishment of highly resistant strains across poultry farms in Albania.

Increased cellular triglyceride levels in human monocytic and rat smooth muscle cells after lovastatin.

Beta-hydroxy-beta-methyl-glutaryl-coenzyme A (HMG-CoA) reductase inhibitors reduce plasma LDL cholesterol by upregulating hepatic LDL receptors. However, their effects on lipid metabolism in extrahepatic cells may also contribute to their therapeutic benefit. We examined the effects of lovastatin (LOV) on cellular lipid levels in the human monocytic Mono Mac 6sr and cultured rat smooth muscle cells. In both cell types, LOV produced a dose-dependent increase in cellular triglycerides. This increase was observed in cells grown in the absence of exogenous lipids in the culture medium, but was more pronounced after additions of oleic acid (50 to 200 microM) and VLDL (50 to 200 microg ml-1). In Mono Mac 6sr cells grown in medium containing 10% delipidated FCS for the last 16 h, the LOV-induced rise in triglyceride levels was completely reversed by 2 mM mevalonic acid and was associated with a decrease in cellular cholesterol. However, when cells were maintained in lipoprotein-replete medium, the LOV-induced rise in triglycerides did not correlate with cellular cholesterol. LOV also reduced cellular cholesterol esterification and increased the synthesis of fatty acids and their incorporation into triglycerides and phospholipids. Increased triglyceride levels were also seen in Mono Mac 6sr cells treated with the lanosterol demethylase inhibitor RS-21607 and the acylcoenzyme A:cholesterol acyltransferase inhibitor SaH 58035. Our findings suggest that the LOV-induced triglyceride accumulation involves changes in intracellular cholesterol pools regulating cellular fatty acid concentrations. Although decreased cholesterol levels in cells participating in plaque formation are beneficial, the impact of the herein described shift in intracellular neutral lipid metabolism on other cellular functions warrants further investigation.

Vapor-phase elemental mercury adsorption by residual carbon separated from fly ash.

The adsorption capacity for vapor-phase elemental mercury (Hg0) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At low mercury concentrations (< 200 microg/m3), unburned carbon had higher adsorption capacity than commercial activated carbon. The adsorbality of unburned carbon was also found to be source dependent. Isotherms of FS carbon (separated from fly ash of a power plant of Shishi in Fujian Province) were similar to those classified as type II. Isotherms of XJ carbon (separated from fly ash of a power plant of Jingcheng in Shanxi Province) were more like those classified as type II. Due to the relatively low production costs, these residual carbons would likely be considerably more cost-effective for the full-scale removal of mercury from combustion flue gases than other technology.

The global threat of antimicrobial resistance: science for intervention.

In the last decade we have witnessed a dramatic increase in the proportion and absolute number of bacterial pathogens resistant to multiple antibacterial agents. Multidrug-resistant bacteria are currently considered as an emergent global disease and a major public health problem. The B-Debate meeting brought together renowned experts representing the main stakeholders (i.e. policy makers, public health authorities, regulatory agencies, pharmaceutical companies and the scientific community at large) to review the global threat of antibiotic resistance and come up with a coordinated set of strategies to fight antimicrobial resistance in a multifaceted approach. We summarize the views of the B-Debate participants regarding the current situation of antimicrobial resistance in animals and the food chain, within the community and the healthcare setting as well as the role of the environment and the development of novel diagnostic and therapeutic strategies, providing expert recommendations to tackle the global threat of antimicrobial resistance.

Corrigendum to "The global threat of antimicrobial resistance: science for intervention" [New Microbes New Infect 6 (2015): 22-29].

[This corrects the article DOI: 10.1016/j.nmni.2015.02.007.].

Role of increased production of superoxide anions by NAD(P)H oxidase and xanthine oxidase in prolonged endotoxemia.

Superoxide anions (O2-) are supposedly involved in the pathogenesis of endothelial dysfunction. We investigated whether the enhanced formation of O2- is involved in the attenuation of endothelium-dependent relaxation induced by lipopolysaccharide (LPS). Rats were injected with LPS (10 mg/kg IP), the aorta was removed after 12 or 30 hours, and generation of O2-, H2O2, and ONOO- was measured using chemiluminescence assays. Protein tyrosine nitration and expression of xanthine oxidase (XO), NAD(P)H oxidase, and manganese superoxide dismutase were determined by Western or Northern blotting, and endothelium-dependent relaxation in aortic rings was studied. LPS treatment increased vascular O2- (from 35+/-2 cpm/ring at baseline to 166+/-21 cpm/ring at 12 hours and 225+/-16 cpm/ring at 30 hours) and H2O2 formation, which was partially sensitive to the NAD(P)H oxidase inhibitor diphenylene iodonium at both time points studied and to the XO inhibitor oxypurinol only 30 hours after LPS treatment. Expression of XO and NAD(P)H oxidase (p22phox, p67phox, and gp91phox) were increased by LPS in a time-dependent manner, as were protein tyrosine nitration and ONOO- formation. LPS also induced expression of the oxidative stress-sensitive protein manganese superoxide dismutase. Endothelium-dependent relaxation was impaired after LPS treatment and could not be restored by inhibition of inducible NO synthase. Inhibition of O2- with superoxide dismutase, oxypurinol, tiron, or the superoxide dismutase mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride did not restore but further deteriorated the relaxation of LPS-treated rings. In summary, treatment of rats with LPS enhances vascular expression of XO and NAD(P)H oxidase and increases formation of O2- and ONOO-. Because removal of O2- compromised rather than restored endothelium-dependent relaxation, a direct role of O2- in the induction of endothelial dysfunction is unlikely. Other mechanisms, such as prolonged protein tyrosine nitration by peroxynitrite (which is formed from NO and O2-) or downregulation of the NO effector pathway, are more likely to be involved.

Synthesis of spiro[isobenzofuran-1(3H),4'-piperidines] as potential central nervous system agents. 5. Conformationally mobile analogues derived by furan ring opening.

Synthesis and antitetrabenazine activity of 4-[2-(arylmethyl)phenyl]piperidines and 4-(benzyloxy)-4-phenylpiperidines, prepared as simplified and possibly more readily synthesized analogues of 3-phenylspiro[isobenzofuran-1 (3H),4'-piperidine], are reported. Several 4-[2-(arylmethyl)phenyl]piperidines display antitetrabenazine activity comparable to imipramine or amitriptyline but are two- to fourfold less active than analogous 3-arylspiro[isobenzofuran-1(3H),4'-piperidines]. Structure--activity relationships for 4-[2p(arylmethyl)phenyl]piperidines are generally similar to the profile established for 3-arylspiro[isobenzofuran-1(3H),4'-piperidines]. Significant antitetrabenazine activity is associated only with derivatives where the arylmethyl group is ortho to the piperidine ring. 4-(Benzyloxy)-4-phenylpiperidines and 4-[2-(arylmethyl)phenyl]-4-piperidinols and the corresponding methyl ethers and esters display weak to modest antitetrabenazine activity. 4-[2-(Arylmethyl)phenyl]-1,2,3,6-tetrahydropyridine derivatives, at best, exhibit modest antitetrabenazine activity, with the exception of 4-[2-(phenylmethyl)phenyl]-1,2,3,6-tetrahydropyridine which is approximately equipotent with amitriptyline. The results of these investigations allow certain speculations to be made with respect to the role of the furan ring in the 3-arylspiro[isobenzofuran-1(3H),4'-piperidines] and antitetrabenazine activity.

Synthesis of spiro[isobenzofuran-1(3H),4'-piperidines] as potential central nervous system agents. 6. Synthesis, 13C NMR, and biological evaluation of cis- and trans-4-amino-3'-arylspiro[cyclohexane-1,1'(3'H)-isobenzofuran] derivatives.

4-(Dimethylamino)- and 4-(methylamino)-3'-arylspiro[cyclohexane-1,1'(3'H)-isobenzofuran] derivatives were prepared as analogues of previously reported 3-arylspiro[isobenzofuran-1(3H),4'-piperidines]. Metalation of benzanilide with n-butyllithium, addition of 4-(dimethylamino)cyclohexanone, and acidification afforded a mixture of cis- and trans-4-(dimethylamino)spiro[cyclohexane-1,1'(3'H)-isobenzofuran]-3'-ones (1a,b), which were separated by fractional crystallization. Addition of aryllithium or aryl Grignard reagents to 1a,b and formic acid reduction afforded cis- and trans-4-(dimethylamino)-3'-arylspiro[cyclohexane-1,1'(3'H)-isobenzofurans] 3a-f, which were converted to secondary amine analogues 5a-e. Tentative stereochemical assignments are based on chemical arguments and are supported by 13C NMR chemical shift data. Marked inhibition of tetrabenazine-induced ptosis is a property of most antidepressants, and significant antitetrabenazine activity is observed for several of these compounds. Optimal antitetrabenazine activity is associated with the cis-3'-phenyl series, and the cis secondary amine 5a is approximately twice as potent as the cis tertiary amine 3a. The various compounds are relatively weak with respect to potentiation of L-5-hydroxytryptophan-induced seizures.

Tricyclics with analgesic and antidepressant activity. 1. [[(Alkylamino)ethyl]thio]dibenz[b,f]oxepins and 10,11-dihydro derivatives.

A series of [[(alkylamino)ethyl]thio]dibenz[b,f]oxepins (I) and their 10,11-dihydro derivatives (II) was synthesized and subjected to broad analgesic/CNS screening. Several analogues of both types, carrying small N-substituents and frequently a nuclear fluorine function, have been found to possess potent analgesic activity in the phenylquinone writhing assay (PQW) and the tail-flick test in mice. Many of these compounds also exhibited significant activity in antagonizing tetrabenazine-induced ptosis, as exemplified by 10b, 16b, and 18b. Results from the mouse jumping test indicated low physical dependence potential for these compounds, and further evidence for a nonnarcotic profile was provided by the absence of significant naloxone interactions with the tail-flick response. Compound 10b did not produce tolerance in mice following chronic administration in the PQW screen.

Resolution, absolute stereochemistry, and enantioselective activity of nomifensine and hexahydro-1H-indeno[1,2-b]pyridines.

Nomifensine and three selected compounds from the series of H4a,H5-trans,H4a,H9b-cis-2,3,4,4a,5,9b-hexahydro-1H-in deno[1,2-b]pyridines have been resolved into their enantiomers. All compounds exhibit pronounced enantioselective activity with respect to their inhibition of tetrabenazine-induced ptosis and potentiation of yohimbine toxicity. Nomifensine exhibits the same preference for one enantiomer with respect to dopamine and norepinephrine reuptake, whereas in the indeno[1,2-b]pyridine series in vitro experiments do not discriminate between the optical antipodes. The absolute stereochemistry of the pharmacologically active enantiomers in both series was determined by X-ray analyses and comparative CD spectra. For biological activity the diphenylmethane is an essential structure feature in both series. Its absolute configuration proved to be 4S for nomifensine and 5S for indenopyridines. The similar pharmacological profile of the two chemical entities is therefore reflected in an identical configuration of this pharmacologically important molecular part.

(+/-)-4-Aryl-4,5-dihydro-3H-1,3-benzodiazepines. 1. Synthesis and evaluation of (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine and analogues as potential antidepressant agents.

A series of (+/-)-4,5-dihydro-4-phenyl-3H-1,3-benzodiazepines and (+/-)-4,5-dihydro-4-phenyl-1H-1,3-benzodiazepines was synthesized as part of a program to develop novel psychotropics. Of these compounds, (+/-)-4,5-dihydro-2,3-dimethyl-4-phenyl-3H-1,3-benzodiazepine (10a, HRP 543) emerged as a potential antidepressant. In in vivo mouse tests (inhibition of tetrabenazine-induced ptosis and potentiation of yohimbine toxicity) which are predictive of antidepressant-like activity, 10a is comparable to amitriptyline. The similarity is also maintained in vitro, as both 10a and amitriptyline inhibit norepinephrine and serotonin uptake into rat brain synaptosomes. No significant inhibition of rat brain monoamine oxidase A or B was found with 10a, nor did the compound potentiate tryptamine-induced seizures. On chronic administration, the number of cortical beta-adrenergic receptor sites was similarly reduced by 10a and desipramine. The anticholinergic activity of clinically useful antidepressants, such as amitriptyline, is a proposed cause of side effects which reduce patient compliance. In contrast to the tricyclics, 10a apparently lacks anticholinergic activity, as evidenced in vitro by negligible displacement of [3H]quinuclidinyl benzylate from rat brain muscarinic receptors and in vivo by insignificant antagonism of the cholinergic stimulation produced by physostigmine or oxotremorine. These data suggest that 10a may be clinically useful as a novel nontricyclic antidepressant which is devoid of anticholinergic side-effect liability. Further evaluation of 10a in nonrodent species is in progress.

Novel tetracyclic spiropiperidines. 1. 3-Aryl-1,3-dihydrospiro[benzo[c]thiophene-1,4'-piperidines] as potential antidepressants.

A series of 3-aryl-1,3-dihydrospiro[benzo[c]thiophene-1,4'-piperidine] derivatives was synthesized and evaluated pharmacologically for potential psychotropic activity. Potent antidepressant-like activity was noted throughout the series, as assessed by tetrabenazine (TBZ) ptosis prevention in mice and potentiation of 5-hydroxytryptophan (5-HTP) induced behavioral effects in rats. A possible therapeutic advantage of the title compounds appears to be the overall low anticholinergic potential in comparison with the classic tricyclic antidepressants. Several congeners with nuclear halogen substitution also exhibited CNS stimulant properties, as evidenced by their ability to induce a dopamine agonist-like stereotypy and to increase the spontaneous motor activity in mice.

Exposure to polychlorinated biphenyls and levels of thyroid hormones in children.

As part of an epidemiologic study on exposure to a toxic waste incineration plant we investigated whether blood concentrations of polychlorinated biphenyls (PCBs), lead, and cadmium, as well as concentration of mercury in 24-hr urine samples were associated with thyroid hormone status. As an indication of status, we determined levels of thyroid-stimulating hormone (TSH), free thyroxine (FT(4)), and free triiodothyronine (FT(3)) in children living in households where [less than/equal to] 10 cigarettes were smoked per day. Eight PCB congeners (PCBs 101, 118, 138, 153, 170, 180, 183, and 187) were measured in whole blood samples. Of these, seven congeners (PCB 101 was not detected in any sample) and the sum of all PCB congeners were analyzed as predictors for thyroid hormone status in separate linear regression models adjusted for potential confounders. In addition, the possible effects of cadmium, lead, and mercury on levels of thyroid hormones were examined. Blood concentrations and information on questionnaire data were available for 320 children 7-10 years of age. We found a statistically significant positive association between the mono-ortho congener PCB 118 and TSH as well as statistically significant negative relationships of PCBs 138, 153, 180, 183, and 187 to FT(3). There was no association for the PCB congeners and FT(4). Blood cadmium concentration was associated with increasing TSH and diminishing FT(4). Blood lead and urine concentration of mercury were of no importance to thyroid hormone levels. The results stress the need for future studies on the possible influences of PCB and cadmium exposure on thyroid hormones, particularly in children. These studies should also take neurologic development into account.

Dissociation of renin and aldosterone during low-dose epinephrine infusion.

Besides its dose-dependent alpha- and beta-adrenoceptor-mediated vascular action, hormonal effects of epinephrine also involve the activation of renin secretion by direct stimulation of renal beta 1-adrenoceptors. To determine the interrelation between increased plasma renin activity in response to epinephrine and plasma aldosterone concentration and renal excretion of potassium and sodium, 26 normal subjects were subjected to 4 h of an intravenous infusion of low-dose epinephrine (12 ng/kg/min). Epinephrine infusion raised mean plasma epinephrine concentration 2.8-fold above control (P < .001). Plasma renin activity (PRA) increased by 56% (P < .01) during epinephrine infusion, whereas plasma aldosterone concentration remained constant. Infusion of epinephrine also resulted in markedly suppressed urinary potassium excretion (-32%; P < .025), while urinary sodium excretion was not altered. Serum potassium was decreased by 4.1% during epinephrine (P < .025). Systolic blood pressure and heart rate did not change, and diastolic blood pressure was slightly reduced by 5 mm Hg (P < .025). In summary, during low-dose epinephrine infusion PRA is markedly increased while plasma aldosterone remains unchanged. The fall in urinary potassium excretion in the presence of reduced serum potassium concentration is most likely mediated via the beta-adrenoceptor-mediated shift of potassium into cells. This in turn may prevent a concomitant rise of plasma aldosterone, which subsequently contributes to the blunted kaliuresis and unchanged natriuresis found during the epinephrine-induced rise of PRA. In conclusion, the epinephrine-induced fall in serum potassium appears to be the predominant regulator of plasma aldosterone concentration even in the presence of a stimulated PRA.

Effects of low-dose epinephrine infusion on cardiovascular and renal responses to water immersion in humans.

Elevated plasma epinephrine concentrations may impair blood pressure homeostasis and renal sodium and volume excretion in response to central hypervolemia. We studied the effects of a low-dose epinephrine infusion (12 ng/kg/min) on cardiovascular and renal responses to a thermoneutral head-out water immersion in eleven healthy men. Responses to water immersion without epinephrine were characterized by significant suppression of plasma renin activity (PRA), plasma aldosterone concentration, and renal norepinephrine excretion, and an augmentation of natriuresis and diuresis. Epinephrine infusion, which raised mean plasma epinephrine concentration 4.3-fold, slightly increased plasma norepinephrine and renal norepinephrine excretion, markedly stimulated PRA (+66.7%), but decreased plasma aldosterone (-11.7%), and augmented renal sodium and volume excretion. Despite the presence of the epinephrine infusion, water immersion continued both to suppress PRA and aldosterone, and to increase natriuresis and diuresis in a qualitatively similar pattern. During all conditions blood pressure and heart rate remained unchanged. It is concluded that physiologic responses to central hypervolemia are not impaired at stress levels of circulating epinephrine. During epinephrine infusion, despite a concomitant increase in plasma norepinephrine and a stimulation of PRA, blood pressure remained constant in response to water immersion due to an augmentation of natriuresis and diuresis.

Pharmacological and biochemical studies with three metabolites of nomifensine.

Three major metabolites (M1, M2, M3) of nomifensine (8-amino-1,2,3,4-tetrahydro-2-methyl-4-phenyl-isoquinoline) are formed by hydroxylation and methoxylation of the phenyl ring. They were compared with nomifensine 1. in various psychopharmacological tests in vivo, carried out in mice after oral or i.p. treatment and 2. in neurochemical in vitro studies, measuring inhibition of noradrenaline (NA), dopamine (DA), and serotonin (5-HT) uptake in rat brain synaptosomes. M1 (4'-hydroxy-nomifensine) was the most active metabolite, while M2 and M3 had little or no effect in pharmacological tests. M1 reversed reserpine hypothermia in doses greater than 2.5 mg/kg, antagonized tetrabenazine catalepsy (ED50 68 mg/kg) and reversed oxotremorine hypothermia (ED50 33 mg/kg). In these tests nomifensine was also active, being about 3-10 times more potent than M1. In contrast to nomifensine M1 had also serotoninergic activity, potentiating both phenelzine-induced twitching (ED50 11 mg/kg) and the anticonvulsant effect of 5-hydroxytryptophan. Moreover, M1 prolonged the hexobarbital sleeping time in doses greater than 10 mg/kg, prevented nicotine-induced convulsions (ED50 58 mg/kg) and reduced the oxotremorine tremor (ED50 59 mg/kg). The LD50 of M1 was 1100 mg/kg orally. In vitro M1 was equipotent with nomifensine in inhibiting DA uptake (IC50 1.5 x 10(-7) M) and twice as active in inhibiting NA uptake (IC50 1.1 x 10(-8) M). In contrast to nomifensine M1 was also a potent inhibitor of 5-HT uptake (IC50 3.3 x 10(-7) M). M2 and M3 were less active than M1 in all experiments.