Search PubMed⌕ Search

Biomedical subjects

G E Taylor

Publications and source records attributed to G E Taylor.

34 records · Page 2Linked to original sources
PubMed1987

Synthesis and resistance to enzymic hydrolysis of stereochemically-defined phosphonate and thiophosphate analogues of P1,P4-bis(5'-adenosyl) tetraphosphate.

Novel analogues of P1,P4-bis(5'-adenosyl) tetraphosphate, Ap4A (1), have been prepared with sulphur substituents at P1 and P4 and either oxygen or methylene bridges at the P2,P3-position. Separation of three isomers of the ApspCH2ppsA species has been achieved by a combination of mplc and hplc and the Rp,Rp, Rp,Sp, and Sp,Sp diastereoisomers identified on the basis of selective enzymatic hydrolysis using snake venom phosphodiesterase. Each of these three isomers is a strong competitive inhibitor of the specific Ap4Aase from Artemia and is highly resistant to the asymmetric cleavage normally catalysed by this enzyme.

Adenine Nucleotides↗
PubMed1986

The response of foliar gas exchange to exogenously applied ethylene.

The responsiveness to ethylene of net photosynthesis and stomatal conductance to water vapor in intact plants was investigated in 13 herbaceous species representing seven plant families. Exposures were conducted in an open, whole-plant exposure system providing controlled levels of irradiance, air temperature, CO(2), relative humidity, and ethylene concentration. Net photosynthesis and stomatal conductance to water vapor in units of moles per square meter per second were measured on recently expanded leaves in control and ethylene-treated plants using a remotely operated single-leaf cuvette. The ethylene concentration was either 0 or 210 micromoles per cubic meter and was maintained for 4 hours. Species varied substantially in the response of their foliar gas exchange to ethylene. In 7 of the 13 species, net photosynthesis was inhibited statistically by 4 hours of ethylene exposure. As a function of the rate in control plants, the responses were most pronounced and statistically significant in Arachis hypogaea (-51.1%), Gossypium hirsutum (-31.7%), Glycine max (-24.8%), Cucurbita pepo (-20.4%), Phaseolus vulgaris (-18.4%), Setaria viridis (-17.5%), and Raphanus sativus (-4.4%). Whereas the responsiveness of net photosynthesis to ethylene among the 13 species showed no specific taxonomic associations, the responsiveness was positively correlated with the intrinsic rate of net photosynthesis. Stomatal conductance to water vapor after 4 hours of ethylene exposure declined statistically in 6 of the 13 species. As a function of control rates, the most marked and statistically significant responses of stomatal conductance were in Glycine max (-53.6%), Gossypium hirsutum (-51.2%), Arachis hypogaea (-42.7%), Phaseolus vulgaris (-38.6%), Raphanus sativus (-26.8%), and Solanum tuberosum (-23.4%). Although ethylene-induced changes in net photosynthesis and stomatal conductance were positively correlated, there were species-specific exceptions in which net photosynthesis declined after 4 hours of exposure without a concurrent change in stomatal conductance, stomatal conductance declined without a change in net photosynthesis, and the decline in stomatal conductance substantially exceeded the corresponding decline in net photosynthesis. Thus, the responsiveness to ethylene of net photosynthesis and stomatal conductance to water vapor were not consistently synchronous or equivalent among the 13 species. It is concluded that foliar gas exchange is responsive to exogenously applied ethylene in many plant species. The sensitivity of foliar gas exchange to ethylene may play a role in general plant response to environmental stress in which one of the physiological sites of action for endogenously produced stress ethylene in the leaf is the plant's photosynthetic capacity and/or stomatal conductance to water vapor.

Journal Article↗
PubMed1985

Promethazine or DPPD pretreatment attenuates oleic acid-induced injury in isolated canine lungs.

Oleic acid causes pulmonary edema by increasing capillary endothelial permeability, although the mechanism of this action is uncertain. We tested the hypothesis that the damage is an oxidant injury initiated by oleic acid, using isolated blood-perfused canine lung lobes. The lobes were dilated with papaverine and perfused in zone III with a constant airway pressure of 3 cmH2O. Changes in isogravimetric capillary pressure (Pc,i) and capillary filtration coefficient (Kf,C) were used as indices of alterations in microvascular permeability in lungs treated with silicone fluid (n = 3), oleic acid (n = 11), oleic acid after pretreatment with the antioxidants promethazine HCl (n = 11) or N,N'-diphenyl-p-phenylenediamine (DPPD; n = 4), or oleic acid following pretreatment with methylprednisolone (n = 4). Kf,C averaged 0.21 +/- 0.02 ml X min-1 X cmH2O-1 X 100 g-1 in control and increased to 0.55 +/- 0.05 and 0.47 +/- 0.05 when measured 20 and 180 min after the administration of oleic acid. When oleic acid was infused into lungs pretreated with promethazine, Kf,C increased to only 0.38 +/- 0.05 ml X min-1 X cmH2O-1 X 100 g-1 after 20 min and had returned to control levels by 180 min. Pretreatment with DPPD, but not methylprednisolone, similarly attenuated the increase in Kf,C following oleic acid. Silicone fluid had no effect on Kf,C. That oleic acid increases vascular permeability was also evidenced by a fall (P less than 0.05) in Pc,i from control when measured at 180 min in every group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Sulfur Dioxide Flux into Leaves of Geranium carolinianum L. : Evidence for a Nonstomatal or Residual Resistance.

The concurrent exchange of SO(2) and H(2)O vapor between the atmosphere and foliage of Geranium carolinianum was investigated using a whole-plant gas exchange chamber. Total leaf flux of SO(2) was partitioned into leaf surface and internal fractions. The emission rate of SO(2)-induced H(2)S was measured to develop a net leaf budget for atmospherically derived sulfur. Stomatal resistance to SO(2) flux was estimated by two techniques: (a) R(s) (SO(2)') from SO(2) data using analog modeling techniques and (b) R(s) (SO(2) ) from analogy to H(2)O (i.e. 1.89 R(s) (H(2)o)).The emission of H(2)S was positively correlated with the rate of SO(2) flux into the leaf interior. An accounting of the simultaneous, bidirectional flux of gaseous sulfur compounds during pollutant exposure showed that sulfur accumulation in the leaf interior of G. carolinianum was 7 to 15% lower than that estimated solely from mass-balance calculations of SO(2) flux data (i.e. ignoring H(2)S emissions).The esimate of stomatal resistance to pollutant flux from the SO(2) data (R(s) (SO(2)')) was consistently less than the simultaneous estimate derived from analogy to H(2)O vapor (R(s) (SO(2) )). The resultant of R(s) (SO(2)') - R(s) (SO(2) ), which was always negative, is indicative of a residual resistance to SO(2) flux into the leaf interior. On a comparative basis, SO(2) molecules experienced less pathway resistance to diffusion than effluxing H(2)O molecules. It is proposed that the SO(2):H(2)O path length ratio is less than unity, as a consequence of the pollutant's high water solubility and unique chemical reactivity in solution. Thus, the diffusive paths for H(2)O and SO(2) in G. carolinianum are not completely synonymous.

Journal Article↗
PubMed1982

Pertussis vaccine inhibits immune insulitis induced with streptozotocin.

Normally, the injection of streptozotocin (STZ) at a lower dose (60 mg/kg body weight) to young (45 days old) CD-1 male mice produces a sustained hyperglycemia with the concomitant development of hypoinsulinemia and immune insulitis in the pancreas, both of which lead to insulin-dependent diabetes (IDD). In an effort to abort the development of IDD, pertussis vaccine (PV) was administered either intraperitoneally (n = 12) or intravenously (n = 12) 3 days prior to STZ injection. In contrast to the control group (n = 12) which received only STZ resulting in the subsequent development of IDD after 16 weeks, none of the vaccinated group developed IDD. The complete protective effect was evidenced by normal insulin values, normoglycemia, the lack of the development of nucleic acid antibody and the absence of insulitis in the vaccinated animals. Under these experimental conditions, PV appeared to offer satisfactory protection of the beta cells of islets in pancreas against the inflammatory effect of STZ.

Animals↗
PubMed1981

Immune insulitis and antibodies to nucleic acids induced with streptozotocin in mice.

Streptozotocin (STZ), a known beta cell toxin, given in a single injection of either a high (100 mg/kg body weight) or a low dose (60 mg/kg body weight) to young (45 days old) CD-I mice induced permanent hyperglycaemia which led to insulin-dependent diabetes (IDD). Further study, however, revealed that the course of the disease was strikingly different between the groups. The average latent period of the high-dose group (n = 20) before the development of hyperglycaemia was only 3 days while that of the low-dose group was 7 weeks (n = 30). Islets of pancreas in the high-dose group showed extensive acute necrosis of the islets with only two out of 20 showing limited mononuclear cell infiltration. In contrast, 20 out of 30 mice in the low-dose group had 45% of their islets heavily infiltrated with mononuclear cells (P less than 0.001). In addition, the deposition of IgG was found in 40% of the islets in 23 out of 30 mice in the low-dose group, in contrast to only two out of 20 in the high-dose group (P less than 0.005). The incidence of antibody to nucleic acids, polyadenylic-polyuridylic acid, polyinosinic-polycytidylic acid, single-stranded DNA and anti-nuclear antibody was significantly higher in the low-dose group as compared to the high-dose group or controls (P less than 0.01). Since the findings in the low-dose group are similar to pathological and serological changes reported in man with recent-onset IDD, this model should be of value in the study of the pathogenesis of this disease.

Animals↗
PubMed1980

Corynebacterium vaginale and vaginitis: a controlled trial of treatment.

In a study of the diagnosis and treatment of Corynebacterium vaginale (Haemophilus vaginalis) vaginitis in 30 patients, clinical and microscopical findings were compared with laboratory cultures. The study also included a double-blind randomised trial of treatment regimens including placebo therapy. Laboratory cultures of C. vaginale corresponded well with clinical findings, and we suggest that C. vaginale vaginitis can be reliably diagnosed with clinical and microscopical findings. Tetracycline was effective in half the patients treated, whereas all but 1 of the 17 patients eventually treated with metronidazole were cured. The apparent discrepancy between in-vitro sensitivity and in-vitro efficacy of metronidazole in this condition is discussed.

Adolescent↗
PubMed1977

Diagnostic medium containing inositol, urea, and caffeic acid for selective growth of Cryptococcus neoformans.

An agar medium containing inositol and urea as sole carbon and nitrogen sources, caffeic acid and ferric citrate as agents for the selective pigmentation of Cryptococcus neoformans, gentamicin as a broad-spectrum bacterial antibiotic, and yeast nitrogen base without amino acids and ammonium sulfate (Difco) was tested against 137 clinical isolates, 4 survey specimens, and 11 ATCC yeast and yeast-like strains. All 28 strains of C. neoformans showed heavy growth and dark brown pigmentation after 36 h. All other tested species of Cryptococcus showed heavy growth after 36 h but only light brown pigmentation after 48 h. No growth was observed in any tested strains of Geotrichum, Pityrosporum, Rhodotorula, Saccharomyces, and Torulopsis. Only the Cryptococcus-like Candida humicola grew of the 8 species and 62 strains of Candida tested. Six of 15 strains of Trichosporon cutaneum and 1 of 2 strains of Trichosporon pullulans showed moderate growth after 48 h. Very different colonial and microscopic morphology and/or the absence of brown pigmentation easily differentiated these strains of T. cutaneum, T. pullulans, and C. humicola from C. neoformans. The growth- and pigmentation-providing characteristics of the medium were unaffected by 2 h of exposure to 254 nm of ultraviolet light.

Agar↗
PubMed1975

Propranolol-augmented, exercise-induced human growth hormone release.

Serum growth hormone (HGH) responses to 20 minutes of exercise 90 minutes after orally given propranolol (0.5 mg/kg; maximum, 40 mg), were assessed in 15 short but otherwise normal children, in 2 obese teen-agers, in 3 hypopituitary children, and in 8 healthy adult volunteers. In six adults HGH responses to exercise alone were also assessed one week previously. Normal children responded with a peak serum HGH concentration of 10 ng/ml or greater, except one whose peak was 7 ng/ml (normal, greater than 7 ng/ml). The obese girls showed smaller responses to exercise with propranolol (ex/prop) (peak HGH, 6 ng/ml), to hypoglycemia, and to levodopa (peak HGH, 7 and 4 ng/ml). The three hypopituitary children did not respond to ex/prop or to two other stimuli. In the volunteer adults, the mean HGH responses were greater to ex/prop than to exercise alone, although two out of six did not have increased levels with exercise. There were also elevations of fasting serum HGH levels before exercise and propranolol on repeat testing. These results suggest that orally given propranolol improves the exercise-HGH stimulation test both in the number of responders and in the degree of response. Some individuals have an anticipatory HGH secretion before exercise due to a conditioned response.

Administration, Oral↗
PubMedDate not supplied

Pneumococcal vaccination in a remote population of high-risk Alaska Natives.

In response to an increasing prevalence of serious pneumococcal disease among adult Alaska Natives of northwest Alaska, a 3-year program was begun in 1987 to identify residents of that remote region who were at high risk for developing invasive pneumococcal disease, to determine their pneumococcal vaccination status, and to deliver vaccine to at least 80 percent of those at risk. After reviewing public health nursing and Indian Health Service data bases, the authors identified 1,337 persons, 20 percent of the 6,692 residents of the region, at high risk for invasive pneumococcal infection, defined either by having a specific chronic disease or by age criteria. Cardiovascular disease and alcoholism were the two most common chronic diseases. Only 30 percent of those determined to be at high risk had received one or more doses of pneumococcal vaccine previously. Half of those persons had received their most recent vaccination 6 or more years earlier. The program used both customary and innovative methods to deliver 23-valent polysaccharide vaccine to 1,046 of those at high risk (78 percent), including 388 persons who were revaccinated. At the completion of the project, 1,123 persons, 84 percent of those at high risk, had received at least 1 dose. They included 1,088 persons, 81 percent of those at high risk, with vaccination within the previous 5 years as a result of the project, compared with a 15-percent rate prior to the vaccination phase of the project. The program demonstrated that high levels of vaccination against pneumococcal disease, exceeding Year 2000 objectives of 60 percent, are attainable in a remote rural Alaskan population.

Adolescent↗