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PubMed1994

1H, 13C, 15N nuclear magnetic resonance backbone assignments and secondary structure of human calcineurin B.

The calmodulin- and calcium-stimulated protein phosphatase calcineurin, PP2B, consists of two subunits: calcineurin B, which binds Ca2+, and calcineurin A, which contains the catalytic site and a calmodulin binding site. Heteronuclear 3D and 4D NMR experiments were carried out on a recombinant human calcineurin B which is a 170-residue protein of molecular mass 19.3 kDa, uniformly labeled with 15N and 13C. The nondenaturing detergent CHAPS was used to obtain a monomeric form of calcineurin B. Three-dimensional triple resonance experiments yielded complete sequential assignment of the backbone nuclei (1H, 13C, and 15N). This assignment was verified by a 4D HN(COCA)NH experiment carried out with 50% randomly deuteriated and uniformly 15N- and 13C-enriched calcineurin B. The secondary structure of calcineurin B has been determined on the basis of the 13C alpha and 13C beta secondary chemical shifts, J(HNH alpha) couplings, and NOE connectivities obtained from 3D 15N-separated and 4D 13C/15N-separated NOESY spectra. Calcineurin B has eight helices distributed in four EF-hand, helix-loop-helix [Kretsinger, R. H. (1980) CRC Crit. Rev. Biochem. 8, 119-174] calcium binding domains. The secondary structure of calcineurin B is highly homologous to that of calmodulin. In comparison to calmodulin, helices B and C are shorter while helix G is considerably longer. As was observed for calmodulin in solution, calcineurin B does not have a single long central helix; rather, helices D and E are separated by a six-residue sequence in a flexible nonhelical conformation.

Amino Acid Sequence↗
PubMed1997

Automated probabilistic method for assigning backbone resonances of (13C,15N)-labeled proteins.

We present a computer algorithm for the automated assignment of polypeptide backbone and 13C beta resonances of a protein of known primary sequence. Input to the algorithm consists of cross peaks from several 3D NMR experiments: HNCA, HN(CA)CO, HN(CA)HA, HNCACB, COCAH, HCA(CO)N, HNCO, HN(CO)CA, HN(COCA)HA, and CBCA(CO)NH. Data from these experiments performed on glutamine-binding protein are analyzed statistically using Bayes' theorem to yield objective probability scoring functions for matching chemical shifts. Such scoring is used in the first state of the algorithm to combine cross peaks from the first five experiments to form intraresidue segments of chemical shifts (Ni,HiN,Ci alpha, Ci beta, Ci'), while the latter five are combined into interresidue segments (Ci alpha,Ci beta,Ci',Ni + 1,Hi + 1N). Given a tentative assignment of segments, the second stage of the procedure calculates probability scores based on the likelihood of matching the chemical shifts of each segment with (i) overlapping segments; and (ii) chemical shift distributions of the underlying amino acid type (and secondary structure, if known). This joint probability is maximized by rearranging segments using a simulated annealing program, optimized for efficiency. The automated assignment program was tested using CBCANH and CBCA(CO)NH cross peaks of the two previously assigned proteins, calmodulin and CheA. The agreement between the results of our method and the published assignments was excellent. Our algorithm was also applied to the observed cross peaks of glutamine-binding protein of Escherichia coli, yielding an assignment in excellent agreement with that obtained by time-consuming, manual methods. The chemical shift assignment procedure described here should be most useful for NMR studies of large proteins, which are now feasible with the use of pulsed-field gradients and random partial deuteration of samples.

Amino Acid Sequence↗
PubMed1997

1H, 13C, and 15N NMR backbone assignments and chemical-shift-derived secondary structure of glutamine-binding protein of Escherichia coli.

1H, 13C, and 15N NMR assignments of the backbone atoms and beta-carbons have been made for liganded glutamine-binding protein (GlnBP) of Escherichia coli, a monomeric protein with 226 amino acid residues and a molecular weight of 24935 Da. GlnBP is a periplasmic binding protein which plays an essential role in the active transport of L-glutamine through the cytoplasmic membrane. The assignments have been obtained from three-dimensional triple-resonance NMR experiments on a 13C, 15N uniformly labeled sample as well as specifically labeled samples. Results from the 3D triple-resonance experiments, HNCO, HN(CO)CA, HN(COCA)HA, HNCA, HN(CA)HA, HN(CA)CO, and CBCA(CO)NH, are the main sources used to make the resonance assignments. Other 3D experiments, such as HNCACB, COCAH, HCACO, HCACON, and HOHAHA-HMQC, have been used to confirm the resonance assignments and to extend connections where resonance peaks are missing in some of the experiments mentioned above. We have assigned more than 95% of the polypeptide backbone resonances of GlnBP. The result of the standard manual assignment is in agreement with that predicted by an automated probailistic method developed in our laboratory. A solution secondary structure of the GlnBP-Gln complex has been proposed based on chemical shift deviations from random coil values. Eight alpha-helices and 10 beta-strands are derived using the Chemical Shift Index method.

Amino Acid Sequence↗
PubMed2002

Novel projected 4D triple resonance experiments for polypeptide backbone chemical shift assignment.

Here we present a novel suite of projected 4D triple-resonance NMR experiments for efficient sequential assignment of polypeptide backbone chemical shifts in 13C/15N doubly labeled proteins. In the 3D HNN[CAHA] and 3D HNN(CO)[CAHA] experiments. the 13C(alpha) and lHalpha chemical shifts evolve in a common dimension and are simultaneously detected in quadrature. These experiments are particularly useful for the assignment of glycine-rich polypeptide segments. Appropriate setting of the 1H radiofrequency carrier allows one to place cross peaks correlating either backbone 15N/1H(N)/13C(alpha) or 15N/1H(N)/H(alpha) chemical shifts in separate spectral regions. Hence, peak overlap is not increased when compared with the conventional 3D HNNCA and HNN(CA)HA. 3D HNN[CAHA] and 3D HNN(CO)[CAHA] are complemented by 3D reduced-dimensionality (RD) HNN COCA and NNCACO, where 13C(alpha) and 13C' chemical shifts evolve in a common dimension. The 13C(alpha), shift is detected in quadrature, which yields peak pairs encoding the 13C' chemical shift in an in-phase splitting. This suite of four experiments promises to be of value for automated high-throughput NMR structure determination in structural genomics, where the requirement to independently sample many indirect dimensions in a large number of NMR experiments may prevent one from accurately adjusting NMR measurement times to spectrometer sensitivity.

Nuclear Magnetic Resonance, Biomolecular↗
PubMed2001

Periodontal disease among indigenous people in the Amazon rain forest.

BACKGROUND: People are not all equally susceptible to periodontitis. To understand the epidemiology and natural history of this disease, it is important to study populations with varying genetic backgrounds and environmental exposures. AIM: Characterize the periodontal condition of a sample of indigenous adults in a remote region of the Amazon rain forest and determine the association of periodontal disease with various demographic, behavioral and environmental factors. METHODS: A cross-sectional evaluation of 244 subjects aged 20-70 years was conducted. Pocket depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), plaque and calculus were assessed for the Ramfjord index teeth. RESULTS: These people had high levels of plaque, calculus and BOP. The mean PD was rather shallow (2.45 mm in 20-29 year-olds to 2.73 mm in 50+ year-olds) and did not increase significantly with age. Mean CAL (0.57 mm in 20-29 year-olds and 2.26 mm in 50+ year-olds) and mean location of the free gingival margin in relation to the cemento-enamel junction changed significantly with age (p<0.0001). Multivariate analysis revealed that increasing age, bleeding on probing and calculus scores were positively associated with mean CAL (p<0.01). Sex, ethnicity, level of modern acculturation, use of coca or tobacco paste, frequency of dental visits and plaque were not associated with mean CAL. CONCLUSIONS: Periodontal disease in these people was mainly associated with gingival recession rather than deep pockets. Most people had clinical attachment loss but despite poor oral hygiene and extensive gingival inflammation, they did not have very severe periodontal destruction.

Acculturation↗
PubMed1989

Dextromethorphan and caffeine as probes for simultaneous determination of debrisoquin-oxidation and N-acetylation phenotypes in children.

The feasibility and reliability of simultaneously determining debrisoquin oxidation and N-acetylation phenotypes was assessed in children with use of two innocuous substrate probes given by mouth, 30 mg dextromethorphan (Pertussin ES) and 25 to 46 mg caffeine (Coca-Cola beverage). Twenty-six children and adolescents (aged 3 to 21 years) were studied three times, once with each substrate given alone and once with the two substrates given together. Urine was collected for 4 hours, and the molar urinary metabolic ratios for dextromethorphan:dextrorphan and for two caffeine metabolites (AFMU:1X) were determined by HPLC ultraviolet assays. The urinary metabolic ratios for both substrates were not significantly different when the substrates were given alone compared with when they were given together. There also was no difference in either the oxidation or acetylation phenotype assignments when the two substrates were given alone and when they were given together. No adverse effects were observed. We conclude that dextromethorphan and caffeine can be given together to simultaneously determine oxidation and acetylation phenotypes and can thereby provide an innocuous, noninvasive method for the assessment of polymorphic drug metabolism in various pediatric populations.

Acetylation↗
PubMed2004

Extraction of arsenic species from spiked soils and standard reference materials.

The abilities of various extractants to recover four arsenic species [As(iii), As(v), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA)] from soils spiked with 20 micro g g(-1) As were investigated. The extractants were water, buffer solutions (citrate and ammonium dihydrogen phosphate), acidic solutions (phosphoric acid and acetic acid), a basic solution (sodium hydroxide) and household chemicals (vinegar and Coca Cola). Gentle shaking at room temperature with each extractant for 24 h gave different recoveries for the different arsenic species. With 0.1 M NaOH solution 46% As(iii), 53% DMA, 100% MMA and 84% As(v) were recovered. A rapid extraction procedure using a sonicator probe has been developed to obtain higher extraction efficiencies. Extracts of arsenic-spiked soil, SRM 2711 Montana soil and SRM 2709 San Joaquin soil were analyzed by HPLC-ICP-MS. In the SRM water extracts, DMA and MMA were identified in addition to inorganic arsenic. The solution detection limits (3s) were 0.1, 0.12, 0.13 and 0.15 ng mL(-1) for As(iii), DMA, MMA and As(v), respectively for HPLC-ICP-MS.

Arsenicals↗
PubMed2003

Preparing nurses to face the pandemic of diabetes mellitus: a literature review.

BACKGROUND: Diabetes constitutes a global public health problem. Today about 135 million people are affected and it is estimated that the number in 2025 will be 300 million. AIMS: By reviewing existing literature the aim is to raise awareness among nurses, nurse educators and nursing students of the global epidemic of diabetes mellitus, its multiple underlying causes, especially social ones, and how to fight it. A further aim is to discuss the implications for future curriculum content in nurse education programmes. FINDINGS: The main underlying causes of the disease are genetic and environmental factors, such as urbanization and industrialization, as well as increased longevity and changes in lifestyle from a traditional healthy and active life to a modern, sedentary, stressful life and over-consumption of energy-dense foods. This process, labelled 'coca-colonization', is evident all over the world, although more so in developing countries. The prevalence of diabetes mellitus varies among populations due to differences in genetic susceptibility and social risk factors such as change in diet, obesity, physical inactivity and, possibly, factors relating to intrauterine development. Migrants are especially affected. Diabetes mellitus needs to be treated by a holistic approach through dietary adjustment, exercise, medication (if needed), education and self-care measures. Type 2 diabetes mellitus is a preventable disease. The main implication for nurses and nursing curricula is to change the focus from the individual with diabetes mellitus and management to prevent deterioration of health (secondary prevention), to population-based community-intervention programmes. These need to focus on health promoting activities to raise awareness among healthy people of the risk factors for diabetes mellitus. CONCLUSION: Nurses all over the world have an important role in fighting the diabetic pandemic by health promotion aimed to keep people healthy as long as possible.

Curriculum↗
PubMed2001

Conduct of an algorithm in quantifying simulated palatal surface tooth erosion.

In order to test the ability of an algorithm to quantify simulated palatal erosion, a total of 10 extracted permanent upper central incisors were mounted in brass blocks. Baseline impressions were recorded using an addition cured silicone impression material in a metal impression tray. Once set and removed from the teeth, the impressions were coated twice with a high silver content electroconductive paint, applied using a brush, before being backed up with die stone to form an electroconductive replica. Each tooth was then subject to three treatments: application of phosphoric acid etchant gel for 60 s, application of etchant gel for 120 s and immersion for 3 h in Diet Coca-Cola*. After each one the replication process was repeated. Thereafter all replicas were mapped using a computer controlled electrical probe and the resultant digital terrain models (DTMS) compared using a surface matching and difference detection algorithm (SMADDA). Surface matching was unsuccessful only in one instance. As the duration of the insult increased, so did the proportion of the surface that underwent change to a maximum of 33.3%. Anatomical site was significantly (P < 0.05) associated with the susceptibility to erosion. The cingulum periphery appeared most resistant to this. The algorithmic approach offers much scope for monitoring dental erosion as acid dissolution of the tooth's surface appears to occur gradually. The cingulum region appears relatively more resistant to this process than other tooth sites and thus facilitates the process of surface matching. Further testing is however, required to determine precisely the algorithm's upper tolerance level.

Algorithms↗
PubMed1999

Angel trumpet lily poisoning in five adolescents: clinical findings and management.

OBJECTIVE: To describe clinical features and management of Angel trumpet lily poisoning in adolescents. METHODOLOGY: Case notes of five adolescent males who presented to the emergency department of a teaching hospital were reviewed. RESULTS: All five boys ingested a mixture of coca-cola and a brew prepared by boiling the leaves and flowers of the plant. They presented to the emergency department with various degrees of agitation and confusion and specific clinical signs. All were treated with charcoal and cathartics and discharged after 36 h. CONCLUSIONS: Due to its hallucinogenic effects, abuse of Angel trumpet lily is not uncommon and should be suspected in adolescents presenting with altered mental state and hallucinations in conjunction with other anticholinergic symptoms and signs.

Adolescent↗
PubMed2000

Body packer: cocaine intoxication, causing death, masked by concomitant administration of major tranquilizers.

Cocaine, derived from the leaves of the shrub Erythroxylon coca, which grows on the slopes of the Andes, remains one of the most widely abused illicit drugs (Johnson et al., 1993). Its abuse appears to be increasing and as a result, so is its trafficking across borders, with ever-increasing sophistication of concealment (Rouse, 1992). Over the past few years, cases of cocaine intoxication have been reported, resulting from ruptured packets of cocaine that have been swallowed, or inserted into the vagina or rectum by couriers (drug smugglers), so called 'body packers' or 'mules' (Westli and Mittleman, 1981; Ricaurte and Langston, 1995). Cocaine is a powerful sympathomimetic and central nervous system stimulant, an overdose of which causes primarily cardiac, neurological and psychiatric effects (Ricaurte and Langston, 1995). Acute toxicity is dose-related and is characterized in the first place by its sympathomimetic effects, which include tachycardia, hypertension and hyperthermia arrythmias, followed by seizures. Brainstem depression and cardio-respiratory collapse, stroke, coma, intracranial vasculitis, myocardial infarction and sudden death have all been reported in cocaine abuse (Ricaurte and Langston, 1995). We present a fatal case with neurological and psychiatric symptoms, but without the usual cardiac and systemic signs.

Adult↗
PubMedDate not supplied

Examining the debate on the use of medical marijuana.

The opium poppy and the coca leaf offer useful perspectives on the current controversies over medical marijuana. In both cases, purified synthetic analogues of biologically active components of ancient folk remedies have become medical mainstays without undermining efforts to reduce nonmedical drug use. A decade ago, a campaign strove to legalize heroin for the compassionate treatment of pain in terminally ill patients. Like the current campaign to legalize medical marijuana, many well-meaning people supported this effort. The campaign for medical heroin was stopped by science when double-blind studies showed that heroin offered no benefits over the standard opioid analgesics in the treatment of severe cancer pain. Scientific medicine requires purified chemicals in carefully controlled doses without contaminating toxic substances. That a doctor would one day write a prescription for leaves to be burned is unimaginable. The Controlled Substances Act and international treaties limit the use of abused drugs or medicines. In contrast to smoked marijuana, specific chemicals in marijuana or, more likely, synthetic analogues, may prove to be of benefit to some patients with specific illnesses. Most opponents of medical use of smoked marijuana are not hostile to the medical use of purified synthetic analogues or even synthetic tetrahydrocannabinol (THC), which has been available in the United States for prescription by any licensed doctor since 1985. In contrast, most supporters of smoked marijuana are hostile to the use of purified chemicals from marijuana, insisting that only smoked marijuana leaves be used as "medicine," revealing clearly that their motivation is not scientific medicine but the back door legalization of marijuana.

Cannabis↗
PubMed2000

Diabetes insipidus in a patient with a highly malignant B-cell lymphoma and stomatitis.

A 37-year-old male patient with a diffuse pleomorphic B-cell-lymphoma, which has been diagnosed two month earlier with the primary site at the pterygopalatine fossa on both sides with infiltration of the clivus and cavernous sinus was referred to our hospital for continuation of the third course of CHOP chemotherapy. At admission he reported about a recent history of painful swallowing and intermittent substernal chest pain. Alleviation of the pain on swallowing and the chest pain was apparently only possible by drinking 10 to 15 l of cold coca cola throughout the day and night, a regimen that resulted in polyuria. Physical examination revealed extensive thrush stomatitis and soor esophagitis. Despite successful treatment with fluconazole, polydipsia continued unabated. The classic osmotic test of dehydration and exogenous vasopressin revealed hypothalamic diabetes insipidus (DI). Basal hormones and stimulated endocrine function tests of the adenohypophysis were found to be normal. MRI-scan revealed lymphoma infiltration of the neurohypophysis. After the third course of CHOP chemotherapy the patient surprisingly recovered completely from his excessive thirst. The present report shows that clinical disorders such as thrush stomatitis can mask diabetes insipidus caused by an early relapsing lymphoma.

Adult↗
PubMed1993

Cocaine as a naturally occurring insecticide.

Although cocaine has a fascinating and complex medicinal history in man, its natural function in plants is unknown. The present studies demonstrate that cocaine exerts insecticidal effects at concentrations which occur naturally in coca leaves. Unlike its known action on dopamine reuptake in mammals, cocaine's pesticidal effects are shown to result from a potentiation of insect octopaminergic neurotransmission. Amine-reuptake blockers of other structural classes also exert pesticidal activity with a rank order of potency distinct from that known to affect vertebrate amine transporters. These findings suggest that cocaine functions in plants as a natural insecticide and that octopamine transporters may be useful sites for targeting pesticides with selectivity toward invertebrates.

Animals↗
PubMedDate not supplied

An overview of cocaethylene, an alcohol-derived, psychoactive, cocaine metabolite.

Cocaethylene is a psychoactive ethyl homologue of cocaine, and is formed exclusively during the coadministration of cocaine and alcohol. Not a natural alkaloid of the coca leaf, cocaethylene can be identified in the urine, blood, hair, and neurological and liver tissue samples of individuals who have consumed both cocaine and alcohol. With a pharmacologic profile similar to cocaine, it can block the dopamine transporter on dopaminergic presynaptic nerve terminals in the brain. It increases dopamine synaptic content, provoking enhanced postsynaptic receptor stimulation, resulting in euphoria, reinforcement, and self-administration. Equipotent to cocaine with regard to dopamine transporter affinity, cocaethylene appears to be far less potent than cocaine with regard to serotonin transporter binding. Lacking the serotonergic-related inhibitory mechanism, cocaethylene appears to be more euphorigenic and rewarding than cocaine. Synthesized and administered cocaethylene has a behavioral stimulation profile similar to cocaine. Cocaethylene has been shown to be less potent and equipotent to cocaine, and alcohol plus cocaine produces more stimulatory locomotor behavior in mice than either drug alone. Equipotent to cocaine with regard to primate reinforcement and self-administration, cocaethylene can substitute for cocaine in drug discrimination studies, and can produce stimulation of operant conditioning in rats. With regard to lethality, cocaethylene has been shown to be more potent than cocaine in mice and rats. The combination of cocaine and alcohol appears to exert more cardiovascular toxicity than either drug alone in humans. Alcohol appears to potentiate cocaine hepatotoxicity in both humans and mice.

Animals↗
PubMed2003

Isolation and 16S DNA characterization of soil microorganisms from tropical soils capable of utilizing the herbicides hexazinone and tebuthiuron.

Six non-fermentative bacteria were isolated from Colombian (South America) and Hawaiian (USA) soils after enrichment with minimal medium supplemented with two herbicides, hexazinone (Hex) and tebuthiuron (Teb). Microscopic examination and physiological tests were followed by partial 16S DNA sequence analysis, using the first 527 bp of the 16S rRNA gene for bacterial identification. The isolated microorganisms (and in brackets, the herbicide that each degraded) were identified as: from Colombia. Methylobacterium organophilum [Teb], Paenibacillus pabuli [Teb], and Micrmbacterium foliorum [Hex]; and from Hawaii, Methylobacterium radiotolerans [Teb], Paenibacillus illinoisensis [Hex], and Rhodococcus equi [Hex]. The findings further explain how these herbicides, which have potential for illicit coca (Erythroxylum sp.) control, dissipate following their application to tropical soils.

Bacteria↗
PubMed1976

Sugar as a vehicle for iron fortification.

Sugar as a vehicle for iron fortification presents several advantages over the other vehicles used in the last three decades. In vitro studies demonstrated that ferrous sulfate added to sugar in proportion of 1 mg to 1 g, respectively, is maintained in the ferrous form for a period of at least 1 year and does not induce adverse changes in the vehicle. Sugar, by itself, carries practically no inhibitors for the absorption of iron. Iron absorption from fortified sugar mixed with vegetals is the same as that of native vegetal iron. The absorption from fortified sugar is increased more than 50% over that observed from native vegetal when it is administered as a drink during the ingestion of a meal. A further increase in absorption was found when fortified sugar was administered with beverages. The mean absorption ratio of fortified sugar given with orange juice, Coca-Cola, and Pepsi-Cola to a reference dose of iron ascorbate was between 0.45 and 0.66, which is more than 3 times the absorption of this iron fortification mixed with vegetals. The mean absorption ratio from coffee was 0.30, and from coffee with milk, 0.15. These data indicate that the fortification of sugar with iron could be a better procedure for the prevention of iron deficiency than the iron fortification of bread and wheat products, from which iron is poorly absorbed. It could be used in developing countries where beverages are highly consumed by the low socioeconomic class. This program could be extended to all sugar consumption or be restricted to soft drinks.

Absorption↗
PubMed1983

Studies on the bioavailability of zinc in humans: intestinal interaction of tin and zinc.

Mineral/mineral interactions at the intestinal level are important in animal nutrition and toxicology, but only limited understanding of their extent or importance in humans has been developed. An inhibitory interaction of dietary tin on zinc retention has been recently described from human metabolic studies. We have explored the tin/zinc interaction using the change-in-plasma-zinc-concentration method with a standard dosage of 12.5 mg of zinc as zinc sulfate in 100 ml of Coca-Cola. Sn/Zn ratios of 2:1, 4:1, and 8:1, constituted by addition of 25, 50, and 100 mg of tin as stannous chloride, had no significant overall effect on zinc uptake. The 100-mg dose of tin produced noxious gastrointestinal symptoms. Addition of iron as ferrous sulfate to form ratios of Sn/Fe/Zn of 1:1:1 and 2:2:1 with the standard zinc solution and the appropriate doses of tin produced a reduction of zinc absorption not dissimilar from that seen previously with zinc and iron alone, and addition of picolinic acid did not influence the uptake of zinc from the solution with the 2:2:1 Sn/Fe/Zn ratio.

Adult↗