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Biomedical subjects

J W Green

Publications and source records attributed to J W Green.

At least 19 recordsLinked to original sources
PubMed2006

Effects of low-dose naloxone on opioid therapy in pediatric patients: a retrospective case-control study.

OBJECTIVE: To develop novel therapies that prevent opioid tolerance in critically ill children we examined the effects of low-dose naloxone infusions on patients' needs for analgesia or sedation. DESIGN AND SETTING: Matched case-control study in a pediatric intensive care unit at a university children's hospital. PATIENTS: We compared 14 pediatric ICU patients receiving low-dose naloxone and opioid infusions with 12 matched controls receiving opioid infusions. MEASUREMENTS AND MAIN RESULTS: Opioid analgesia and sedative requirements were assessed as morphine- and midazolam-equivalent doses, respectively. No differences were observed between groups in opioid doses at baseline or during naloxone, but in the postnaloxone period opioid doses tended to be lower in the naloxone group. Compared to baseline the naloxone group required more opioids during naloxone but fewer opioids after naloxone. Total sedative doses were comparable at baseline in both groups, with no differences in the postnaloxone period. The naloxone group required less sedation after naloxone but sedation doses were unchanged in controls. The two groups did not differ in pain scores, sedation scores, or opioid side effects. CONCLUSIONS: Naloxone did not reduce the need for opioid during the infusion period but tended to reduce opioid requirements in the postnaloxone period without additional need for sedation. Randomized clinical trials may examine the effects of low-dose naloxone on opioid tolerance and side effects in pediatric ICU patients requiring prolonged opioid analgesia.

Analgesia↗
PubMed2002

Rapid integrity assessment of rat and human epidermal membranes for in vitro dermal regulatory testing: correlation of electrical resistance with tritiated water permeability.

An approach is presented that allows for rapid selection of robust rat and human epidermal membranes for use on in vitro dermal regulatory studies. Tritiated water (THO) permeability was correlated with electrical resistance (ER) and the results used to propose ER values to judge membrane integrity. Rat and human epidermal membranes were prepared and mounted onto in vitro glass static diffusion cells (0.64 cm(2)) maintained at 32 degrees C. THO permeability coefficients (Kp) were determined and compared with ER measurements. Electrical resistance was also determined for various in vitro cell exposure areas from 0.64 cm(2) to 2.54 cm(2). Our results show that rat epidermal membrane THO Kp values exhibited a lognormal distribution with a median value of 2.76 x 10(-3) cm/h. Human epidermal membrane THO Kp values were best described by a Weibull distribution with a median value of 1.13 x 10(-3) cm/h. The corresponding median electrical resistance measurements were 5.59 kOmega for rat and 23 kOmega for human epidermal membranes. Based on the widely used and accepted single point THO Kp thresholds of </=2.5 x 10(-3) cm/h (rat) and </=1.5 x 10(-3) cm/h (human), the corresponding ER values of >/=5.87 kOmega and >/=17.1 kOmega were calculated and proposed as acceptable benchmarks for pre-qualifying membranes. In our research exploring the relationship between ER and exposure area we report that an inverse relationship exists between ER and in vitro cell exposure area; as cell area increased, ER decreased. The use of electrical resistance provides a rapid and reliable method for evaluating the integrity of rat and human epidermal membranes for in vitro dermal kinetic testing.

Administration, Topical↗
PubMed2001

A review of the genotoxicity of marketed pharmaceuticals.

Information in the 1999 Physician's Desk Reference as well as from the peer-reviewed published literature was used to evaluate the genotoxicity of marketed pharmaceuticals. This survey is a compendium of genotoxicity information and a means to gain perspective on the inherent genotoxicity of structurally diverse pharmaceuticals. Data from 467 marketed drugs were collected. Excluded from analysis were anti-cancer drugs and nucleosides, which are expected to be genotoxic, steroids, biologicals and peptide-based drugs. Of the 467 drugs, 115 had no published gene-tox data. This group was comprised largely of acutely administered drugs such as antibiotics, antifungals, antihistamines decongestants and anesthetics. The remaining 352 had at least one standard gene-tox assay result. Of these, 101 compounds (28.7%) had at least one positive assay result in the pre-ICH/OECD standard four-test battery (bacterial mutagenesis, in vitro cytogenetics, mouse lymphoma assay (MLA), in vivo cytogenetics). Per assay type, the percentage of positive compounds was: bacterial mutagenesis test, 27/323 (8.3%); in vitro cytogenetics 55/222 (24.8%); MLA 24/96 (25%); in vivo cytogenetics 29/252 (11.5%). Of the supplemental genetic toxicology test findings reported, the sister chromatid exchange (SCE) assay had the largest percentage of positives 17/39 (43.5%) and mammalian mutagenesis assays (excluding MLA) had the lowest percentage of positives 2/91 (2.2%). The predictive value of genetic toxicology findings for 2-year bioassay outcomes is difficult to assess since carcinogenicity can occur via non-genotoxic mechanisms. Nevertheless, the following survey findings were made: 201 drugs had both gene-tox data and rodent carcinogenicity data. Of these, 124 were negative and 77 were equivocal or positive for carcinogenicity in at least 1 gender/1 species. Of the 124 non-carcinogens, 100 had no positive gene-tox findings. Of the remaining 24, 19 were positive in in vitro cytogenetics assays. Among the 77 compounds that exhibited equivocal or positive effects in carcinogenesis studies, 26 were positive in gene-tox assays and 51 were negative. Of the 51 negatives, 47 had multiple negative gene-tox assay results suggesting that these are probably non-genotoxic carcinogens. Statistical analyses suggested that no combination of gene-tox assays provided a higher predictivity of rodent carcinogenesis than the bacterial mutagenicity test itself.

Animals↗
PubMed2001

Variation in therapy and outcome for pediatric head trauma patients.

OBJECTIVE: This study was undertaken to examine variation in therapies and outcome for pediatric head trauma patients by patient characteristics and by pediatric intensive care unit. Specifically, the study was designed to examine severity of illness on admission to the pediatric intensive care unit, the therapies used during the pediatric intensive care unit stay, and patient outcomes. DATA SOURCES AND SETTING: Consecutive admissions from three pediatric intensive care units were recorded prospectively (n = 5,749). For this study, all patients with an admitting diagnosis of head trauma were included (n = 477). Data collection occurred during an 18-month period beginning in June 1996. All of the pediatric intensive care units were located in children's hospitals, had residency and fellowship training programs, and were headed by a pediatric intensivist. METHODS: Admission severity was measured as the worst recorded physiological derangement during the period 1 yr old (16.1% vs. 6.1%; p = .002). Comparisons by insurance status indicated that observed mortality rates were highest for self-paying patients. However, patient characteristics were not associated with use of therapies or standardized mortality rates after adjustment for patient severity. There was significant variation in the use of paralytic agents, seizure medications, induced hypothermia, and intracranial pressure monitoring on admission across the three pediatric intensive care units. In multivariate models, only the use of seizure medications was associated significantly with reduced mortality risk (odds ratio = 0.17; 95% confidence interval = 0.04-0.70; p = .014). CONCLUSIONS: Therapies and outcomes vary across pediatric intensive care units that care for children with head injuries. Increased use of seizure medications may be warranted based on data from this observational study. Large randomized controlled trials of seizure prophylaxis in children with head injury have not been conducted and are needed to confirm the findings presented here.

Child, Preschool↗
PubMed2001

Benefit-cost analysis of animal identification for disease prevention and control.

Individual animal identification is an important consideration for many countries to improve animal traceback systems. The analysis presented by the authors provides a conceptual benefit-cost framework for evaluating the economic usefulness of improved animal identification systems designed to reduce the consequences of foreign animal diseases (FAD). For cattle in situations similar to those found in the United States of America, results show that improved levels of animal identification may provide sufficient economic benefits, in terms of the reduced consequences of FAD, to justify the improvements. In contrast, the results of similar studies in swine show that the economic benefits of the reduced FAD consequences are not sufficient to justify improvements in animal identification systems. Vertically integrated industries, in which animals have only one owner in a closed system from birth to slaughter, may not require individual animal identification for traceback purposes. However, additional benefits, not quantified in this analysis, could contribute to favourable benefit-cost ratios for improved identification in certain sectors of the swine industry.

Animal Diseases↗
PubMed2000

Chronic toxicity and oncogenicity bioassay in rats with the chloro-s-triazine herbicide cyanazine.

Cyanazine is a member of the chloro-s-triazine class of herbicides. Other triazine herbicides have been shown to induce mammary-gland tumors in rats, although the response is unique to the Sprague-Dawley strain. Cyanazine is nongenotoxic. The present study was conducted to evaluate the chronic toxicity and oncogenic potential of cyanazine. Groups of 62 male and female rats were fed diets containing cyanazine at concentrations of 1, 5, 25, or 50 ppm for up to 2 yr. Mean body weight and body weight gain of male and female rats of the 25- and 50-ppm groups were significantly reduced over the course of the study. Food consumption and food efficiency were also reduced in these groups. Survival was not adversely affected in the treatment groups compared to controls. A significant increase in the incidence of masses of the inguinal region was noted among female rats of the 50-ppm group. These masses were correlated with a significant increase in the incidence of female rats with mammary-gland adenocarcinomas and carcinosarcomas. The incidence of rats with malignant mammary-gland tumors was elevated in the 5-, 25-, and 50-ppm groups, although the incidence within the 5-ppm group was within historical controls. There were no other toxicologically significant observations with respect to ophthalmological, clinical laboratory, or pathological evaluations. Under the conditions of this study, the no-observed-adverse-effect level was 5 ppm. Research into the mechanism of action suggests these mammary tumors are mediated through a prolactin mechanism that is thought to be of low relevance to humans.

Adenocarcinoma↗
PubMed2000

Volume-outcome relationships in pediatric intensive care units.

CONTEXT: Pediatric intensive care units (PICUs) have expanded nationally, yet few studies have examined the potential impact of regionalization and no study has demonstrated whether a relationship between patient volume and outcome exists in these units. Documentation of an inverse relationship between volume and outcome has important implications for regionalization of care. OBJECTIVES: This study examines relationships between the volume of patients and other unit characteristics on patient outcomes in PICUs. Specifically, we investigate whether an increase in patient volume improves mortality risk and reduces length of stay. DESIGN AND SETTING: A prospective multicenter cohort design was used with 16 PICUs. All of the units participated in the Pediatric Critical Care Study Group. Participants. Data were collected on 11 106 consecutive admissions to the 16 units over a 12-month period beginning in January 1993. MAIN OUTCOME MEASURES: Risk-adjusted mortality and length of stay were examined in multivariate analyses. The multivariate models used the Pediatric Risk of Mortality score and other clinical measures as independent variables to risk-adjust for illness severity and case-mix differences. RESULTS: The average patient volume across the 16 PICUs was 863 with a standard deviation of 341. We found significant effects of patient volume on both risk-adjusted mortality and patient length of stay. A 100-patient increase in PICU volume decreased risk-adjusted mortality (adjusted odds ratio:.95; 95% confidence interval:.91-.99), and reduced length of stay (incident rate ratio:.98; 95% confidence interval:.975-.985). Other PICU characteristics, such as fellowship training program, university hospital affiliation, number of PICU beds, and children's hospital affiliation, had no effect on risk-adjusted mortality or patient length of stay. CONCLUSIONS: The volume of patients in PICUs is inversely related to risk-adjusted mortality and patient length of stay. A further understanding of this relationship is needed to develop effective regionalization and referral policies for critically ill children.

Child↗
PubMed1994

Testicular maturation in prepubertal New Zealand white rabbits.

Testicular maturation was assessed in age-matched, sexually immature (13-17-week-old) New Zealand white rabbits using end points frequently evaluated in toxicity studies: testicular weight and testicular histology. Testicular weights and testicular maturity as assessed histologically were markedly variable in sexually immature rabbits, especially at > or = 14 weeks of age. The large variation in testicular weights in immature rabbits requires that large changes in a treatment group relative to controls be present for statistical detection of testicular weight effects at commonly used significance levels. Testicular weights and testicular maturity were strongly correlated to one another, but neither weight nor maturity was strongly correlated to body weight. Thus, stratification and randomization of immature rabbits to study groups based upon body weight will not assure an absence of group differences with respect to testicular maturity. The large variation in testicular weights and maturity in 13-17-week-old rabbits warrants caution in the evaluation of testicular changes when rabbits of this age range are used in toxicity studies.

Animals↗
PubMed1992

Increased susceptibility of the sickle cell membrane Ca2+ + Mg(2+)-ATPase to t-butylhydroperoxide: protective effects of ascorbate and desferal.

Normal and sickle cell erythrocyte membranes were examined for significant differences in their ATPase activities, thiobarbituric acid reactive products formed (measured relative to malondialdehyde), membrane protein polymerization, and number of protein-free sulfhydryl groups when treated with 0.5 mmol/L t-butylhydroperoxide (tBHP) for 30 minutes. Isolated sickle cell membranes treated with tBHP produced significantly greater inhibition in both their basal and calmodulin-stimulated Ca2+ + Mg(2+)-ATPase activities (75% inhibition in both cases) compared with that of control membranes. In addition, there was significantly more malondialdehyde formed from sickle cell membranes compared with control membranes. Oxidation caused greater protein polymerization in sickle cell membranes compared with normal membranes as demonstrated by the formation of high molecular weight polymers separated on sodium dodecyl sulfate polyacrylamide gels. The number of free sulfhydryl groups present in spectrin and actin decreased more in sickle cell membranes as measured by 3H-N-ethyl maleimide autoradiography and gel scanning. To prevent enzyme inhibition, erythrocyte membranes were treated with tBHP in the presence of 1 mmol/L ascorbate, a potential antioxidant, and 1 mmol/L desferal, an iron chelator. Both ascorbate and desferal added alone with tBHP were effective in preventing inhibition of the basal and calmodulin-stimulated Ca2+ + Mg(2+)-ATPase activities in normal membranes, but in sickle cell membranes only the addition of ascorbate and desferal together offered significant protection. The enhanced oxidation observed with sickle cell membranes can be mimicked in normal white membranes by adding hemoglobin, hemin, or ferrous chloride in the presence of tBHP. In contrast to hemoglobin, ferrous chloride has the ability to enhance membrane oxidation in the presence of ascorbate with or without tBHP. Furthermore, the addition of desferal to these membranes greatly decreased the iron-ascorbate-tBHP oxidation of erythrocyte membranes as determined by the sustained ATPase activities and the reduced formation of malondialdehyde. Maximal protection was provided by 1 mmol/L desferal in the presence of 1 mmol/L ascorbate, although some protection was observed even at 10 mumol/L, the lowest concentration tested. These results are discussed in light of the pro- and anti-oxidant effects of ascorbate in the absence and presence of iron and tBHP.

Anemia, Sickle Cell↗
PubMed1989

Microfossils from silicified stromatolitic carbonates of the Upper Proterozoic Limestone-Dolomite 'Series', central East Greenland.

Silicified flake conglomerates and in situ stratiform stromatolites of the Upper Proterozoic (c. 700-800 Ma) Limestone-Dolomite 'Series', central East Greenland, contain well preserved microfossils. Five stratigraphic horizons within the 1200 m succession contain microbial mat assemblages, providing a broad palaeontological representation of late Proterozoic peritidal mat communities. Comparison of assemblages demonstrates that the taxonomy and diversity of mat builder, dweller, and allochthonous populations all vary considerably within and among horizons. The primary mat builder in most assemblages is Siphonophycus inornatum, a sheath-forming prokaryote of probable but not unequivocally established cyanobacterial affinities. An unusual low diversity unit in Bed 17 is dominated by a different builder, Tenuofilum septatum, while a thin cryptalgal horizon in Bed 18 is built almost exclusively by Siphonophycus kestron. Although variable taphonomic histories contribute to observed assemblage variation, most differences within and among horizons appear to reflect the differential success or failure of individual microbial populations in colonizing different tidal flat microenvironments. Twenty-two taxa are recognized, of which two are described as new: Myxococcoides stragulescens n.sp. and Scissilisphaera gradata n. sp.

Biological Evolution↗
PubMed1989

Treatment of type I decompression sickness using the U.S. Navy treatment algorithm.

The effectiveness of the U.S. Navy (USN) Diving Manual treatment algorithm in treating pain-only decompression sickness (DCS) was analyzed. Treatment logs from the Naval Diving and Salvage Training Center and the Navy Experimental Diving Unit during the decade 1976-1986 were examined. Two hundred and ninety-two cases diagnosed initially as pain-only DCS were identified. Using the treatment algorithm, 208 cases were completed on USN Treatment Table 5 (TT-5), and 84 cases completed on USN Treatment Table 6 (TT-6). Recurrence of symptoms was 4.3% after TT-5, and 3.6% following TT-6. Difference in rate of recurrence was not statistically significant between treatment tables. Overall, the success rate for following the USN treatment algorithm was 95.9%. These data support the use of the shorter TT-5 in accordance with the Navy treatment algorithm.

Algorithms↗
PubMed1988

Microfossils from oolites and pisolites of the Upper Proterozoic Eleonore Bay Group, Central East Greenland.

Silicified oolites and pisolites from Bed 18 of the Upper Proterozoic (about 700-800 Ma) Limestone-Dolomite "Series" of the Eleonore Bay Group, central East Greenland, contain a diverse suite of organically preserved microfossils that is, for the most part. [Of the] assemblages previously described from Proterozoic cherts and shales. Three principal assemblages occur in these rocks: 1) a class bound assemblage found in detrital carbonate grains (now silicified) that served as nuclei for ooid and pisoid growth, as well as in uncoated mud and mat clasts that were carried into the zone of ooid and pisoid deposition; 2) an epilithic and interstitial assemblage consisting of microorganisms that occurred on top of and between grains; and 3) a euendolithic assemblage composed of microbes that actively bored into coated grains. The Upper Proterozoic euendolithic assemblage closely resembles a community of euendolithic cyanobacteria found today in shallow marine ooid sands of the Bahama Banks. Thirteen species are described, of which eight are new, five representing new genera: Eohyella dichotoma n. sp., Eohyella endoatracta n. sp., Eohyella rectoclada n. sp., Thylacocausticus globorum n. gen. and sp., Cunicularius halleri n. gen. and sp., Graviglomus incrustus n. gen. and sp., Perulagranum obovatum n. gen. and sp., and Parenchymodiscus endolithicus n. gen. and sp.

Calcium Carbonate↗
PubMed1987

Paleobiology of distinctive benthic microfossils from the upper Proterozoic Limestone-Dolomite "Series," central East Greenland.

Populations of Polybessurus bipartitus Fairchild ex Green et al., a large morphologically distinctive microfossil, occur in silicified carbonates of the Upper Proterozoic (700-800 Ma) Limestone-Dolomite "Series," central East Greenland. Large populations of well-preserved individuals permit reconstruction of P. bipartitus as a coccoidal unicell that "jetted" upward from the sediment by the highly unidirectional secretion of extracellular mucopolysaccharide envelopes. Reproduction by baeocyte formation is inferred on the basis of clustered envelope stalks produced by small cells. Sedimentological evidence indicates that P. bipartitus formed surficial crusts locally within a shallow peritidal carbonate platform. Among living microorganisms a close morphological, reproductive, and behavioral counterpart to Polybessurus is provided by populations of an as yet underscribed cyanobacterium found in coastal Bahamian environments similar to those in which the Proterozoic fossils occur. In general morphology and "jetting" behavior, this population resembles species of the genus Cyanostylon, Geitler (1925), but reproduces via baeocyte formation. Polybessurus is but one of the more than two dozen taxa in the richly fossiliferous biota of the Limestone-Dolomite "Series." This distinctive population, along with co-occurring filamentous cyanobacteria and other microfossils, contributes to an increasingly refined picture of ecological heterogeneity in late Proterozoic oceans.

Calcium Carbonate↗
PubMed1982

Effects of divalent cations, trypsin, and phospholipases on the passive permeability to sodium of inside-out vesicles from human red cells.

Inside-out vesicles (IOV) were prepared from human red blood cells. Steady-state uptake of 23Na was observed to generally follow an exponential time course with a rate constant of 1.57 +/- 0.09 h-1 (SE). One week of cold storage (0-4 degrees C) increased the rate constant to 2.50 +/- 0.12 h-1 (SE). Mg2+, Ca2+, or Sr2+ decreased the rate of 22Na uptake with no observable differences between the three divalent cations when tested at concentrations of 50 microM. Mg2+ was shown to decrease the rate of 22Na uptake at concentrations as low as 5 microM with maximal effect at 50 to 100 microM. The decrease in rate of 22Na uptake induced by Mg2+ could be enhanced by exposure of IOV to Mg2+ for longer periods of time. Trypsin treatment of OIV increased the rate of uptake of 22Na and was dependent on the concentration of trypsin added between 5 to 25 micrograms/ml (treated for 5 min at 25 degrees C). The ability of Mg2+ (50 microM) to decrease the rate of 22Na uptake was still observed after maximal trypsin treatment. Phospholipase A2 or phospholipase C treatment of IOV increased the rate of 22Na uptake and was dependent on the amount of phospholipase A2 (0.1 to 1.0 units/ml) or phospholipase C (0.25 to 2.5 units/ml) added (treated for 5 min at 25 degrees C). After phospholipase A2 treatment, the observed decrease in the rate of 22Na uptake induced by Mg2+ (50 microM) was generally greater than controls. After phospholipase C treatment, the observed decrease in rate of 22Na uptake induced by Mg2+ (50 microM) was less or absent when compared with controls. Phospholipase C treatment was less effective in preventing the Mg2+ effect the longer IOV were exposed to Mg2+. The results suggest that Mg2+ binds to phospholipid headgroups to reduce Na permeability perhaps by inducing a change in bilayer structure or phospholipid association.

Cations, Divalent↗
PubMed1978

Stimulation of calcium transport in inside-out vesicles of human erythrocyte membranes by a soluble cytoplasmic activator.

Transport of Ca2+ by inside-out vesicles requires both Mg2+ and ATP and can be linear over 16 min at 37 degrees C. This basal rate of transport may be doubled however by an activator found in membrane-free erythrocyte hemolysate. This activatior is probably the same protein (s) which has been shown to activate (Ca2+ + Mg2+)-ATPase in erythrocyte membrane fragments (Bond, G.H. and Clough, D.E. (1973) Biochim. Biophys. Acta 323, 592--599).

Biological Transport, Active↗
PubMed1977

Postoperative wound infection: a controlled study of the increased duration of hospital stay and direct cost of hospitalization.

The increased hospital stay and direct cost of hospitalization that resulted from a postoperative wound infection (presence of pus at the incision site) after each of 6 common operations were evaluated. With the aid of the hospital computer, matched controls were obtained with respect to patient age, sex, exact operation performed, clinical service performing operation, pathologic finding, and underlying disease process which might alter the patient's predisposition toward infection. Several of the operations (appendectomy. cholecystectomy, total abdominal hysterectomy, and coronary artery bypass graft) were subtyped in order to obtain equivalence between controls and infected patients. In general, an infection doubles the postoperative stay and significantly increases the hospital expense.

Adolescent↗