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Biomedical subjects

Robert L Jones

Publications and source records attributed to Robert L Jones.

27 records · Page 2Linked to original sources
PubMed2003

Blood lead levels and risk factors for lead poisoning among children in a Mexican smelting community.

The authors evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs in children 1-6 yr of age living in Torreón, Mexico, and assessed risk factors for lead exposure in these children. The study involved a simple random sample of households in the area around a local smelter, as well as a 2-stage cluster sample of neighborhoods and households in the remainder of Torreón. The geometric mean BLL of children in this study (N = 367) was 6.0 microg/dl (95% confidence interval [CI] = 5.2, 6.8) (0.29 microM/l [95% CI = 0.25, 0.33]). Twenty percent of the children had BLLs > or = 10 microg/dl (0.48 microM/l), and 5% had BLLs > or = 20 microg/dl (0.97 microM/l). In multivariate analyses, distance from the smelter, amount of income, and education level of the primary caregiver predicted BLLs. In the environmental risk factor subsample (n = 124), dust and soil lead levels were associated with BLLs and distance from the smelter. BLLs in this study were moderately high, but the levels were lower than those in other smelting communities prior to remediation.

Child↗
PubMed2002

Actions of prostanoids to induce emesis and defecation in the ferret.

Several prostanoids were investigated for their ability to induce emesis and/or defecation and tenesmus in the ferret. The rank order of emetic potency (dose producing four episodes, D4) was: sulprostone (5 microg/kg)>11alpha,9alpha-epoxymethano-15S-hydroxyprosta-5Z,13E-dienoic acid (U46619; 8 microg/kg)>misoprostol (27 microg/kg)>17-phenyl-omega-trinor prostaglandin E2 (53 microg/kg)>prostaglandin E2 (94 microg/kg)>5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-hydroxypropyl) hydantoin (BW245C; 148 microg/kg)>>prostaglandin F(2alpha) (13,500 microg/kg). Emesis was also induced by iloprost (D4 not determined) and prostaglandin E2 methyl ester (D4=350 microg/kg). Cicaprost and fluprostenol were virtually inactive; they also failed to modify copper sulphate (100 mg/kg, intragastric)-induced emesis (P>0.05), although cicaprost potentiated apomorphine (0.25 mg/kg, s.c.)-induced emesis (P<0.05). U46619-induced emesis was antagonised by vapiprost (P<0.05). The rank order of potency to produce defecation and tenesmus (dose producing three episodes) was: sulprostone (12 microg/kg)>misoprostol (15 microg/kg)>17-phenyl-omega-trinor prostaglandin E2 (94 microg/kg)>prostaglandin E2 (113 microg/kg)>fluprostenol (158 microg/kg)z.Gt;prostaglandin F(2alpha) (1759 microg/kg); prostaglandin E2 methyl ester also induced defecation (196 microg/kg). Data are discussed in relation to mechanisms involved in emesis and defecation.

Animals↗
PubMed2002

Zinc, iron, and sodium in hair of deer from areas of contrasting soil productivity.

The contribution of soils to animal biology through the soil's effect on the ecosystem is an important concept in ecology. Zinc, Fe, and Na contents were determined in autumnal collections of hair of fawn white-tailed doe deer (Virginianus odocoilcus) from two areas of contrasting soil productivity. The area-weighted soil productivity of one area was 40 compared with 79 for the other area. Hair collections were made in each of 8 consecutive years. The mean difference in dressed weight of fawn does collected from these areas in late autumn over 4 yr amounted to 7.2 kg. Some of this weight difference was presumed to be accounted for by a difference in the level of mineral nutrition because the amount of forage was not limiting in either area. Considering the total sample of 8 yr, the mean contents of Zn were 96 and 98, of Fe were 42 and 45, and of Na were 38 and 36 mg/kg for the respective areas. None of the elements was significantly different each year over the observation period. In 3 yr, at least one of the elements differed, and in 1 yr all three differed. The contents of the elements were not related to April through August precipitation, which was considered a measure of plant-available water thought to be important in mineral absorption by forage vegetation. Zinc was significantly different in 29 of the 56 between-year comparisons within areas; Fe differed in 2 and Na in 14 comparisons. The site of collection of the doe was known within a 2.6-km2 area for about 80% of the samples for one of the areas and 90% for the other; therefore, either a soil series or soil association could be identified with the deer. Soils were grouped into two categories in each sampling area; the groupings reflected the intensity of weathering and leaching in one area, and in the other case where soil weathering was not as well developed, substantial soil taxonomic contrast related to grass or deciduous tree vegetation associated with soil development. Only Fe in hair from does collected in the more intensively weathered soil area was significantly different, perhaps reflecting higher levels of plant-available Fe made available to plants because of breakdown of Fe-bearing minerals.

Animals↗
PubMed2002

The upward spiral of drug costs: a time series analysis of drugs used in the treatment of hemophilia.

BACKGROUND: Hemophilia is an expensive disease because its treatment is heavily dependent on costly clotting factor drugs. Over the last nine years,a consortium of three Comprehensive Hemophilia Treatment Centers and other hospitals, which purchased clotting factors for their patients, has seen treatment costs escalate on average 17% annually. Currently, new, even more expensive drugs are entering the market. METHODS: This study analyzes 3,244 purchases that were made over a nine-year period totaling nearly 500 million units of clotting factor, representing every product on the market. Purchases were made both apart from and under the Federal Public Health Service (PHS)discount pricing rules. FINDINGS: The main cause of the increases was the move to newer, more expensive products. The average price of existing products increased less than 2%per year, but new products were priced, on average, 47% higher than existing products. Overall consumption increased by an average of 5% per year, likely reflecting prophylactic treatment modalities that require greater amounts of clotting factor. Government pricing programs, such as the PHS program, were ineffective or counterproductive at reducing costs. There is a notable absence of competition in this market, with a few dominant companies having a functional monopoly in the largest segments of the market. Prices of older products are not lowered, even when new products are brought to market. A few products that serve small patient groups have had their prices increased substantially. INTERPRETATION: This escalation is likely to continue as new, more expensive clotting factor drugs are developed. Since these new products are not proven to be any safer or more effective than the current products, this situation creates a risk of intervention by government and insurers to address both treatment costs and exhaustion of patients' insurance caps. Drug companies are not serving the patients by pricing new, but often very similar, products so aggressively. The trends seen in this patient group will likely be seen in other patient groups in the future. Ultimately, doctors and patients will lose treatment options and health care availability unless collaborative strategies are developed to reduce costs.

Blood Coagulation Factors↗
PubMedDate not supplied

Synergism between prostanoids and other vasoactive agents.

BACKGROUND: Prostaglandin E2 is usually considered to be a vasodilator, but some vascular beds respond with weak vasoconstriction mediated by prostanoid EP3-receptors. We have used the guinea pig isolated thoracic aorta to examine the nature of the synergism between the EP3 agonist sulprostone and other vasoactive agents. METHODS: Muscle tension was recorded from endothelium-denuded rings of aorta suspended in conventional organ baths. Indomethacin and the TP-receptor antagonist GR 32191 were usually present. RESULTS: Sulprostone (0.1-300 nM) showed two profiles: low-responder preparations (maximum response = 15-35% of 100 nM U-46619 response) were insensitive to the L-type Ca2+ blocker nifedipine, whereas high-responders (maximum = 35-70%) showed a nifedipine-sensitive component at higher sulprostone concentrations only. Charybdotoxin (CTX), a blocker of large-conductance Ca2+-activated K+ channels (BKCa), slightly enhanced threshold sulprostone responses and markedly enhanced larger responses; the enhancements were abolished by nifedipine. In contrast, threshold sulprostone responses were dramatically enhanced in the presence of established small contractions to phenylephrine (alpha1-adrenoceptor agonist), U-46619 (TP agonist), cyclopiazonic acid (sarcoplasmic Ca2+ pump inhibitor), and 4-aminopyridine (4-AP, Kv channel blocker). Nifedipine had no effect on enhancements of threshold sulprostone responses, and partially inhibited the enhancements of larger responses. CONCLUSIONS: BKCa channel activation appears to increase progressively as sulprostone-induced contraction increases. CTX removes this "BKCa brake," thereby providing an "L-type channel" Ca2+ flux to prime the EP3-receptor-driven Ca2+-sensitization mechanism (via Rhokinase activation, unpublished observations). In contrast, the other agents, including 4-AP, direct a non-L-type channel source of Ca2+ to the calmodulin-myosin light chain arm.

Animals↗