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J Talbot

Publications and source records attributed to J Talbot.

At least 55 records · Page 3Linked to original sources
PubMed1994

Pharmacokinetic profile of a new fluoride preparation: sustained-release monofluorophosphate.

The pharmacokinetic profiles of a sustained-release monofluorophosphate (MFP-SR) preparation (76 mg) and of plain MFP (76 mg) were compared in six osteoporotic females. These studies were performed in a randomized, crossover, double-blind design to select a preparation that would result in therapeutic serum levels while avoiding high serum peak values. Following a single dose of 76 mg MFP-SR, the serum fluoride levels remained within the accepted therapeutic range (5-10 microM/liter) for 24 hours. In contrast, following a single dose of 76 mg plain MFP, serum fluoride levels exhibited a wide circadian fluctuation and serum levels approximately threefold higher than those of the MFP-SR preparation (9.5 +/- 1.6 vs 3.5 +/- 0.8 microM/liter, P < 0.005). Compared with plain MFP, the sustained-release MFP had a significantly lower peak concentration (Cmax MFP-SR: 10.6 +/- 3 vs CmaxMFP: 18.9 +/- 5 microM/liter, P < 0.005) and a significantly longer absorption lag time (TmaxMFP-SR 7.3 +/- 1.6 vs TmaxMFP: 3.0 +/- 0.6 h, P < 0.05). Twenty-four-hour urinary fluoride excretion after ingestion of plain or SR fluoride was significantly increased from pretreatment values documenting absorption with either MFP formulation. Our results show that the use of sustained-release MFP preparation that we tested prevents the development of high peak levels associated with the use of plain MFP preparations. Furthermore, a single dose of MFP-SR resulted in serum fluoride levels within the accepted range of 5-10 microM/liter for 24 hours.

Aged↗
PubMed1993

Antibody detection errors due to acidic or unbuffered saline.

Isotonic saline solutions, buffered with potassium phosphate or sodium phosphate salts, were evaluated in parallel with unbuffered saline to determine if they improved antibody detection by solid phase red cell adherence or hemagglutination methods. Saline buffered to a pH of 7.0 to 7.5, when used to suspend red cells or to wash sensitized red cells in preparation for the antiglobulin test, produced the best positive solid phase and hemagglutination results. The pH range of commercially prepared blood bank saline (unbuffered) was found to be 5.8 to 6.8, far lower than the desired pH for optimum antibody detection. In the case of solid phase assays employing intact, immobilized reagent red cells, saline with a pH of 7.0 to 7.5 also eliminated falsely positive results due to the dissociation of red cell monolayers from the solid support surface that occurred in the presence of unbuffered or acidic saline. These findings indicate that unbuffered isotonic saline should not be used in solid phase- or hemagglutination-based antibody detection tests. It is recommended that phosphate-buffered saline at a pH of 7.0 to 7.5 be employed.

Journal Article↗
PubMed1992

Bone-resorption markers galactosyl hydroxylysine, pyridinium crosslinks, and hydroxyproline compared.

We compared the clinical performances of four bone-resorption (BR) assays (hydroxyproline, HYP; galactosyl hydroxylysine, GHYL; deoxypyridinoline, DPD; and pyridinoline, PYD) in subjects with different BR rates: normal (adult men and premenopausal women), mildly increased (postmenopausal osteoporotic women), high (Paget disease patients), and very high (children). The discrimination power (Z score) and the accuracy (estimated by receiver-operating characteristic analysis) for GHYL, DPD, and PYD were compared with those for HYP. Discrimination power and accuracy were similar for high- and very-high-BR groups for all four assays. However in the mildly increased-BR group, DPD, GHYL, and PYD showed a higher discrimination power and accuracy than did HYP. The clinical performances of HYP, DPD, GHYL, and PYD are comparable for large changes in BR. For modest changes, DPD, GHYL, and PYD are more accurate and have a higher discrimination power than does HYP.

Adult↗
PubMed1991

pH-sensitive control of arginase by Mn(II) ions at submicromolar concentrations.

The manganese dependence of arginase was reinvestigated with extracts of mouse liver to see whether more physiological properties were displayed than have been reported for the purified enzyme. In a preincubation with Mn(II) ions at 37 degrees C the enzyme underwent a slow and reversible activation. At least 90-95% of the activation achieved was dependent on Mn2+. However, no Mn2+ was required for catalytic activity in the assay. The activation showed little dependence upon pH over the range 6.5-9.5, whereas the catalytic activity increased 12-fold in apparent accord with the titration curve of an ionizable group of pKa 7.9. The Mn2+ dependence of arginase activation obeyed Michaelis-Menten kinetics, with Kd varying from 0.3 microM at pH 6.8 to 0.08 microns at pH 7.7. Free Mn2+ concentrations were established in these assays with a trimethylenediaminetetraacetate-Mn buffer. Vmax increased about three-fold over this range. The calculated arginase activity at 0.05 microM Mn2+ increases about nine-fold over this physiological pH range. An enzyme model is proposed to explain these findings. The activity of arginase at "physiological" [Mn2+] and the pronounced pH dependence conferred upon it are consistent with a recently revised role for the urea cycle in the control of bicarbonate and pH in the body. It appears possible that arginase loses Mn2+ sensitivity during the usual purification.

Animals↗
PubMed1991

Genetic counselling for myotonic dystrophy: a comparison of lens examination and DNA linkage studies.

Genetic counselling in presymptomatic individuals with a family history of myotonic dystrophy (DM) is problematic. A genetic test to identify the presymptomatic carrier of the gene for DM would therefore be advantageous. We report studies comparing ophthalmic examination with a genetic test based on DNA linkage studies in nine DM families. The genetic test involved the use of five probes from four loci linked to the DM locus. Some discrepancies between ophthalmic and genetic tests were observed. Genetic counselling following prediction of genetic status was possible for 18 out of 20 patients from seven out of nine families.

Adolescent↗
PubMed1991

[Determination of serum activity of placental alkaline phosphatase].

The authors have developed an enzymatic method for the measurement of serum placental alkaline phosphatase (PLAP) based on the hydrolysis of paranitrophenyl phosphate into para-nitrophenol. The specificity for the isoenzyme involved is achieved by means of its characteristics thermostability. After one hour incubation at 60 degrees C, PLAP still maintains its full activity, while other isoenzymes are completely inactivated. The sensitivity of the method was improved (less than 1 U/l) by optimizing parameters such as the volume of specimen, the nature of the buffer (2-methyl-amino-ethanol), the reaction time and the pH. Analysis of the method performances has revealed a lower detection limit of 0.12 U/l, a linearity from 0 to 50 U/l, a precision lower than 10% for most of the analytical range and a complete enzyme recovery. The reference range was estimated from 0 U/l to 0.33 U/l in a group of 125 non-smokers without any cancerous disease.

Alkaline Phosphatase↗
PubMed1991

Diabetes prevalence in Alaska, 1984-1986.

The prevalence of diabetes in Alaska from 1984 to 1986 was determined through medical records review. Cases were identified from hospital and physician discharge forms and from financial abstracts. As of December 1986, 3,719 Alaskans met the criteria for physician diagnosis of diabetes. The overall age-adjusted prevalence of diagnosed diabetes mellitus, 1,357/100,000, was lower than the U.S. rate of 2,470/100,000. The overall age-adjusted prevalence rates of specific complications and pregnancy among Alaskans with diabetes were retinopathy--167.5/1,000; blindness--24.3/1,000; amputations--19.4/1,000; end stage renal disease--9.7/1,000; pregnancy--50.7/1,000. Limitations in available data sources such as death certificates, hospital records, and subspecialists' medical records provided serious problems in identifying persons with diabetes, especially those in the 30- to 69-year age group who have not yet developed complications requiring hospitalization or subspecialty care. This population perhaps is most in need of services to prevent future complications of diabetes.

Adolescent↗
PubMed1990

Haemangioma of the optic disc.

Isolated capillary haemangiomata of the optic disc are uncommon; they may be associated with the von Hippel-Lindau syndrome. Renal carcinoma occurs in almost one-third of patients with this condition, and it may go unnoticed until metastases occur. Early nephrectomy offers a cure. It is important, therefore, that all patients with optic disc capillary haemangiomata as well as their relatives are referred for screening for the stigmata of this disease.

Adult↗
PubMed1990

External ocular pigmentation secondary to perforating eye injury.

The dispersal of pigment centrifugally through the conjunctiva from the site of a repaired traumatic perforation was observed. Iris tissue had been incarcerated in the wound for three days prior to surgical repair. Conjunctival biopsies were examined by light and electron microscopy. Light microscopy revealed a normal, non-pigmented conjunctival epithelium and numerous pigment-laden cells in the substantia propria. Electron microscopy showed these cells to contain melanosomes closely resembling those found in normal iris posterior pigment epithelium. The causes of abnormal external ocular pigmentation are discussed.

Conjunctival Diseases↗