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Biomedical subjects

C A Price

Publications and source records attributed to C A Price.

At least 73 records · Page 4Linked to original sources
PubMed1993

Impact testing of denture base polymers.

Acrylic resin has been the denture base material of choice since its initial production in 1936, due to its aesthetic properties and ease of processing. It would be desirable, however, to have a material which is also unbreakable under clinical conditions. A wide range of materials has been suggested for use as denture base materials. The impact resistance of a polysulphone denture base polymer has been compared with that of a linear poly(methyl methacrylate) and four rubber-methacrylate denture base polymers. When tested under oral conditions, the polysulphone material had an impact resistance about twice as high as the best rubber-methacrylate and about four times as high as ordinary poly(methyl methacrylate).

Acrylic Resins↗
PubMed1992

Reversible inhibitors of the gastric (H+/K+)-ATPase. 2. 1-Arylpyrrolo[3,2-c]quinolines: effect of the 4-substituent.

Further work on compounds 1 has identified the 4-position as a site where substantial modifications are tolerated, leading to analogues which are more potent and less toxic than those described previously. The best compound in the series is 13a (SK&F 96356), which is a potent inhibitor of gastric acid secretion in both the pentagastrin-stimulated rat and the histamine-stimulated dog. This compound shows reversible, K(+)-competitive binding to the enzyme. Because of its fluorescent properties, it is also proving useful in vitro as a probe of the structure and function of the (H+/K+)-ATPase.

Adenosine Triphosphatases↗
PubMed1992

Effect of testosterone and bovine follicular fluid on concentrations of luteinizing hormone and follicle-stimulating hormone in plasma of castrated rams that are homozygous carriers or non-carriers of the Booroola fecundity gene.

Castrated adult FecBFecB and Fec+Fec+ Booroola rams were injected with charcoal-treated bovine follicular fluid (bFF) (a source of inhibin-like activity) or given testosterone implants to examine whether the fecundity gene (FecB) influences sensitivity to negative feedback hormones in males. Mean concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) did not differ between genotypes before treatment. In Expt 1, injections of 5 ml bFF, but not of 1 ml (each given four times at intervals of 8 h), significantly (P < 0.05) depressed concentrations of LH and FSH, but there was no effect of genotype. After treatment, gonadotrophin concentrations returned to pretreatment values and for 2-2.5 days scaled (divided by pretreatment mean) LH values (235 +/- 49 for FecBFecB and 96 +/- 26% for Fec+Fec+ rams; P < 0.05) and scaled FSH values (106 +/- 5 for FecBFecB and 85 +/- 5% for Fec+Fec+ rams; P < 0.05) were significantly higher in FecBFecB than in Fec+Fec+ rams in the group that received 5 ml bFF. Irrespective of genotype, treatment with 5 ml bFF did not reduce mean FSH to concentrations observed in testis-intact rams. In Expt 2, Silastic envelopes were implanted subdermally to give physiological or supraphysiological circulating concentrations of testosterone. Both doses significantly reduced scaled LH values in a biphasic manner, such that there was an initial suppression followed by a short-lived increase. During the initial period of suppression in the lower dose group, mean scaled LH values were significantly higher in FecBFecB than in Fec+Fec+ rams (48.3 +/- 7.5 versus 23.1 +/- 5.5%; P < 0.05). Low doses of testosterone decreased LH pulse frequency in both genotypes but decreased (P < 0.05) pulse amplitude and mean concentrations in the Fec+Fec+ animals only. In nonimplanted control rams, mean LH concentrations (in samples taken every 10 min for 12 h) were significantly lower in FecBFecB than in Fec+Fec+ rams (0.6 +/- 0.2 versus 1.3 +/- 0.1 ng ml-1; P < 0.05). The mean FSH response to testosterone was not related to genotype. These data suggest that expression of the FecB gene results in an altered sensitivity of the pituitary gland to changes in negative feedback from testicular hormones and that, irrespective of genotype, neither testosterone nor inhibin-like activity alone can fully control FSH secretion in castrated rams.

Animals↗
PubMed1992

Issues related to the care of critically ill patients with end stage renal failure.

End stage renal disease (ESRD) affects every aspect of an individual's lifestyle. Pharmacologic, dietary, and treatment options and other organ involvement become daily realities for ESRD patients. When ESRD patients are admitted to intensive care units, these realities become concerns for the nurses. This article addresses the considerations that must be included in the nursing interventions for the critically ill ESRD patients.

Critical Care↗
PubMed1992

An update on continuous renal replacement therapies.

Acute renal failure in the critically ill patient is associated with high mortality. Often these patients are hemodynamically unstable, require judicious fluid management, and have a variety of electrolyte abnormalities and acid/base disturbances. Therapeutic intervention is a necessity, but the patient may not tolerate an aggressive approach. Renal replacement therapies have advanced over the years to modalities that allow for improved management of the patient with acute renal failure. The content to follow will bring new promise to the treatment of acute renal failure employing continuous renal replacement therapy.

Acute Kidney Injury↗
PubMed1991

Plasma LH, FSH and testosterone concentrations in adult rams which were homozygous carriers or non-carriers of the Booroola fecundity gene.

No gene-specific differences were found with respect to LH or testosterone pulsatile secretion (over 12 h), or in 12 hourly mean FSH concentrations in adult Booroola FF and ++ rams. Also, no differences between genotypes in the LH response to an injection of testosterone propionate, the FSH response to an infusion of bovine follicular fluid, or the testosterone response to injections of PMSG were noted. However, during the phase of seasonal testicular development, mean testosterone pulse amplitude (over 12 h) and the FSH response to 25 micrograms GnRH were higher in FF than in ++ rams (P less than 0.05); there were also significant effects of sire (P less than 0.05 in FF genotype only) and litter size (P less than 0.05) on testosterone pulse amplitude and GnRH-stimulated FSH release, respectively. During the breeding season, mean LH, but not FSH, concentrations were higher in FF than in ++ rams, after an injection of 0.5 micrograms GnRH; LH release was not affected by sire or litter size (P greater than 0.05). Long-term studies revealed that the FF rams were born in significantly larger litters, they weighed significantly less than ++ rams (P less than 0.05), and that bodyweight was significantly correlated (P less than 0.05) with litter size. There were no differences in testis size, and testis size was not significantly correlated with bodyweight. There was a strong tendency (P = 0.056) for overall mean FSH concentrations, measured weekly for 9 months, to be highest more often in FF than in ++ rams.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of castration on plasma concentrations of luteinizing hormone and follicle-stimulating hormone in adult Merino rams which were homozygous carriers or non-carriers of the Booroola fecundity gene.

Before castration, the mean plasma concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) did not differ between FF and ++ Booroola rams. After castration, mean LH and FSH concentrations increased after 8 h, and for the next 14 days the rate of increase in FSH, but not LH, secretion was significantly faster in FF than in ++ rams (P less than 0.05). Mean FSH concentrations over this period were significantly higher in FF than in ++ rams (P less than 0.05). In both genotypes, the ranked FSH values did not significantly change their order over time, i.e. a significant within-ram effect was noted (P less than 0.05). Repeated-measures analysis of variance indicated a significant effect of genotype on mean FSH secretion (P less than 0.05) and a significant effect of sire in the FF (P less than 0.05), but not the ++ (P = 0.76), genotype. From Day 28 to Day 58 after castration, FSH and LH concentrations were variable and no overall increases in concentrations were observed. The mean concentrations of both hormones over this period were not related to genotype. There were no gene-specific differences in pulsatile LH secretion 14 weeks after castration. However, the mean LH, but not FSH, response to a bolus injection of 25 micrograms of gonadotrophin-releasing hormone (GnRH) was significantly higher in FF than in ++ rams (P less than 0.05) and this was not significantly affected by sire. These studies support the hypothesis that the F gene is expressed in adult rams, in terms of pituitary responsiveness to an injection of GnRH and to the removal of the testes, but it is not clear from this study whether the influence of sire is related to or independent of the apparent gene-specific differences.

Animals↗
PubMed1991

Continuous renal replacement therapy: the treatment of choice for acute renal failure.

The health care issues facing society today are complex. Access to care, quality of life, relative value scales, diagnosis related groups, and cost containment demands have had an impact on the decision-making processes of health care professionals. The availability of alternative therapeutic treatment modalities adds additional considerations when prescribing medical therapy. This is especially true when a patient is diagnosed with renal failure. In the past, either peritoneal dialysis or hemodialysis have been the only therapies for supporting patients with acute renal failure. This article explores continuous renal replacement therapy for the management of acute renal failure: what it is, when and where it should be used, and the responsibilities of nephrology and critical care nurses and physicians.

Acute Kidney Injury↗
PubMed1990

Reversible inhibitors of the gastric (H+/K+)-ATPase. 1. 1-Aryl-4-methylpyrrolo[3,2-c]quinolines as conformationally restrained analogues of 4-(arylamino)quinolines.

The 4-(arylamino)quinoline 4, previously described as an antiulcer compound, is shown to be an inhibitor of the gastric (H+/K+)-ATPase. It is postulated that 1-arylpyrrolo[3,2-c]quinolines 6 act as conformationally restrained analogues of 4. A series of derivatives of 6 has been prepared and shown to be potent inhibitors of the target enzyme in vitro. Substitution in the ortho position of the aryl ring is important for activity. Unsaturation in the 5-membered ring makes little difference, but introduction of heteroatoms into the same ring markedly reduces activity. In more detailed kinetic experiments, 15c and 4 both show reversible, K(+)-competitive binding to the enzyme, with submicromolar Ki values. The compounds appear to act at the lumenal face of the enzyme and to require protonation for activity. Several compounds in the series are shown to be potent inhibitors of pentagastrin-stimulated acid secretion in the rat.

Adenosine Triphosphatases↗
PubMed1990

ChrA Is a Carotenoid-Binding Protein in Chromoplasts of Capsicum annuum.

Chromoplasts of Capsicum annuum var Albino contain a carotenoid-protein complex, which migrates as a brilliant orange band in gels under conditions of nondenaturing electrophoresis. In a second, denaturing separation, the complex resolves into a principal protein (ChrA) of 58 kilodaltons and several minor proteins of 20 to 55 kilodaltons, which may be adventitiously associated. Analysis of Western blots of both one- and two-dimensional gels showed that the principal protein component of the carotenoid complex is ChrA, a protein previously shown to be located specifically in chromoplast membranes. The identification of ChrA as a carotenoid-binding protein appears to be the first instance of a nonthylakoid, carotenoid-binding protein in higher plants.

Journal Article↗
PubMed1990

Treatment of digoxin intoxication in a renal failure patient with digoxin-specific antibody fragments and plasmapheresis.

A patient with renal failure due to myeloma kidney and coincident digitalis intoxication due to prescribed daily digoxin administration was treated with digoxin-specific antibody fragments and plasmapheresis. Rapid response to therapy was noted, removal of digoxin-antidigoxin antibody complexes was confirmed, and prevention of delayed rebound toxicity was documented. We suggest that this is the therapy of choice in similar individuals.

Acute Kidney Injury↗
PubMed1989

2-[[(4-Amino-2-pyridyl)methyl]sulfinyl]benzimidazole H+/K+-ATPase inhibitors. The relationship between pyridine basicity, stability, and activity.

The benzimidazole sulfoxide class of antisecretory H+/K+-ATPase inhibitors need to possess high stability under neutral physiological conditions yet rearrange rapidly at low pH to the active sulfenamide 2. Since the initial reaction involves internal nucleophilic attack by the pyridine nitrogen, control of the pyridine pKa is critical. In this paper we show that by utilizing the powerful electron-donating effect of a 4-amino substituent on the pyridine, moderated by the electron-withdrawing effect of a 3- or 5-halogen substituent, a combination of high potency (as inhibitors of histamine-stimulated gastric acid secretion) and good stability under physiological conditions can be obtained. Furthermore, the role of the steric interaction between the 3/5-substituents and the 4-substituent in modifying the electron-donating ability of the 4-amino group is exemplified, and additional factors affecting stability are identified. One compound, in particular, 2-[[(3-chloro-4-morpholino-2- pyridyl)methyl]sulfinyl]-5-methoxy-(1H)-benzimidazole (3a, SK&F 95601), was chosen for further development and evaluation in man.

Adenosine Triphosphatases↗
PubMed1989

Synthesis of Two Chromoplast-Specific Proteins During Fruit Development in Capsicum annuum.

The time-course of accumuiation of two membrane proteins during fruit ripening was examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blots in tissue extracts of Capsicum annuum L., vars Emerald Giant, Albino, and DNAP VS-12. The proteins, named ChrA and ChrB, were previously shown to occur specifically in chromoplasts. Fruit development was divided into five stages based on changes in color. ChrA was not detectable in the first three stages, but accumulated to a high level in the fully mature, red fruit. ChrB was not detectable in the first, mature-green stage of fruit maturation, but was found in the second stage, when carotenoid accumulation first appeared, and in all later stages. The patterns of accumulation in chromoplasts that develop from proplastids or leucoplasts are similar to those in chromoplasts that develop from chloroplasts. We conclude that ChrA and ChrB are probably synthesized de novo during chromoplast development.

Journal Article↗
PubMed1989

Ovarian response to hCG treatment during the oestrous cycle in heifers.

The aims of this study were to investigate whether treatment with a single ovulatory dose of hCG, between the day of oestrus and the end of the luteal phase, could induce extra ovulations in heifers and whether the presence of an existing corpus luteum (CL) affected the response. Heifers (N = 32) were injected with 1500 i.u. hCG or saline on a given day of the oestrous cycle. Treatments were repeated during subsequent cycles to provide a total of 71 observations, 57 of which followed an injection of hCG, given between Day 0 (oestrus) and Day 16, and 14 of which followed saline injections as controls. Ovulatory responses were noted by laparoscopy 2 days after hCG treatment. No heifers injected with saline produced additional CL. Of the hCG-treated cycles, 23 resulted in the formation of an additional CL, and this was significantly affected by the stage of the oestrous cycle when hCG was given; a greater response was observed during the early (Days 4-7) and late (Days 14-16) stages of the luteal phase than at the mid-luteal phase of the oestrous cycle. Two heifers were also treated with hCG on Days 17 or 18 of the oestrous cycle, but before oestrus; both had induced CL. There were no significant differences between the left-right orientation of the existing CL or the hCG-induced CL. These results demonstrate that the large, luteal-phase follicle of the cow is capable of ovulating in response to hCG and that the induced CL is not affected by the presence of an existing CL.

Animals↗