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Biomedical subjects

R Henley

Publications and source records attributed to R Henley.

At least 19 recordsLinked to original sources
PubMed1997

Two years' experience with an enhanced chemiluminescent assay for neonatal blood spot TSH.

We have developed a blood spot assay for thyroid stimulating hormone (TSH) based on the Amerlite TSH-30 serum assay for use in the Welsh neonatal hypothyroid screening programme. A total of 67,656 infants were screened in 1994 and 1995, and 28 cases of primary hypothyroidism were detected, giving a prevalence of one in 2416. The method is sensitive and rapid, results being available within 3 h of receipt of samples. The assay enables much faster detection of primary hypothyroidism than was previously possible, and therefore contributes to earlier treatment of affected infants.

Congenital Hypothyroidism↗
PubMed1996

Blood ferritin concentrations in newborn infants and the sudden infant death syndrome.

Liver iron concentrations have been shown to be higher in victims of SIDS than in postmortem controls suggesting that high levels of tissue iron may be implicated in SIDS. To determine whether infants who subsequently die from SIDS are born with greater iron stores than those who do not, the iron stores in newborn infants were assessed retrospectively by measuring blood ferritin concentration in spots from Guthrie cards (collected from almost all infants born in the UK in the first week of life). A method for extracting and measuring ferritin from stored blood spots is described. Eighteen cases of SIDS were identified in South Glamorgan along with four controls for each case. Ferritin concentrations did not differ in SIDS victims and controls suggesting that victims of SIDS are not born with abnormal concentrations of stored iron. If iron stores are found to be higher in SIDS victims than in healthy live infants of the same age then it is more likely that the iron will have been acquired after birth.

Blood Preservation↗
PubMed1994

Testosterone levels during systemic and inhaled corticosteroid therapy.

Testosterone has importance both as a sex hormone and as an anabolic steroid promoting bone formation. Osteoporosis is associated with both hypogonadism and corticosteroid therapy. Testosterone levels are reduced by long term prednisolone treatment. Although high dose inhaled corticosteroid therapy may cause a variety of systemic effects including adrenal suppression, dermal thinning and a reduction in total bone calcium, its effect on testosterone levels is not known. Testosterone, luteinizing hormone, follicle stimulating hormone and sex hormone binding globulin were therefore measured in 35 male patients with respiratory disease attending an outpatient clinic (median age 58, range 21-75 years). They were grouped according to steroid therapy and compared with 19 age matched controls. Mean (SD) testosterone levels were 33% lower in 12 men on long term oral prednisolone [14.5 (6.0) nmol 1-1] than in controls [21.7 (6.3) nmol 1-1], but were not significantly reduced in 10 patients on low dose inhaled beclomethasone [200-800 micrograms day-1: 19.7 (3.7)] nor in 13 men taking high dose inhaled beclomethasone [1500-2,250 micrograms day-1: 17.9 (5.6)]. Levels of luteinizing hormone, follicle stimulating hormone and sex hormone binding globulin were similar in all four groups. These cross sectional data confirm that long term systemic corticosteroid therapy reduces testosterone levels. However, testosterone was reduced by only 18% (NS) by long term inhaled corticosteroids. Other mechanisms to explain the disordered bone metabolism should now be explored.

Administration, Inhalation↗
PubMed1993

A comparison of total and free beta-HCG assays in Down syndrome screening.

Free beta-HCG is a new analyte that has been suggested to be superior to total HCG when used in combination with alpha-fetoprotein (AFP) for Down syndrome risk screening in early pregnancy. We have evaluated this claim on 21 samples collected from Down syndrome pregnancies and 180 samples from unaffected pregnancies. The detection rates for the combination of AFP with free beta-HCG or the combination of AFP with total HCG were identical (71 per cent) but the initial screen positive rate (equivalent to the false-positive rate) was 7.5 per cent for AFP + free beta-HCG screening compared with 3.5 per cent for AFP + total HCG screening. We conclude that the case for free beta-HCG is unproven and suggest that further data be collected before free beta-HCG becomes acceptable.

Biomarkers↗
PubMed1991

Luminol peroxidation catalyzed by human isoferritins.

The role of ferritin in catalyzing the oxidation of luminol with the production of chemiluminescence was investigated. The effect of pH was compared to its effect on K3Fe(CN)6-catalyzed oxidation and different pH optima were recorded for the two catalysts. The ferrous iron chelator, bipyridyl, enhanced the production of chemiluminescence catalyzed by FeSO4 and ferritin but had little effect on the K3Fe(CN)6-catalyzed reaction. Desferal reduced the level of chemiluminescence in the presence of FeSO4 and ferritin but was a much more effective inhibitor of chemiluminescence catalyzed by K3Fe(CN)6. The hydroxyl radical scavenger, mannitol, had little effect upon light production whereas superoxide dismutase inhibited light production. The addition of antihuman spleen ferritin completely inhibited activity. The catalytic activity of both H and L rich ferritins was affected by iron content. Activity increased until the Fe/protein ratio reached 0.04 micrograms Fe/micrograms protein and then decreased with increasing iron content. Thus activity is controlled by the iron content of the molecule and influenced by its subunit composition as is the uptake of iron into ferritin. These findings suggest that ferroxidation by ferritin is associated with the ability to generate radicals of the nitrogenous base luminol with the production of chemiluminescence. Although activity is greatest at alkaline pH there is significant activity at pH 7.4. Ferritin therefore may be able to generate free radical reactions in vivo with the acidic isoferritin being most active.

2,2'-Dipyridyl↗
PubMed1990

Methylprednisolone acetate does not cause inflammatory changes in the epidural space.

Few studies have examined the possible adverse effects that epidural injection of depot corticosteroid preparations may have on meningeal membranes and nervous tissue. Thirty-six healthy adult white rabbits received 0.3 ml/kg epidural injections of either lactated Ringer's solution (negative control group), 1% lidocaine containing methylprednisolone acetate (study group), or normal saline containing talc (positive control group). Animals were killed either 4 or 10 days after injection and stained sections of the spinal cord and meningeal membranes were examined by light microscopy. In all animals that received either lactated Ringer's solution or lidocaine with methylprednisolone acetate, microscopic examination of specimens taken from the L5-L6 interspace revealed no white cell infiltrates and no fibroblastic activity. All animals that received epidural injections of normal saline containing talc had marked infiltration of tissue macrophages in the epidural space. There was no thickening of the meningeal membranes or nerve roots in any animal. The complete lack of inflammatory changes and meningeal thickening demonstrated in this pilot study helps to confirm the safety of methylprednisolone acetate when injected into the epidural space.

Animals↗
PubMed1990

Concentrations of free thyroxin and free triiodothyronine in serum of patients with thyroxin- and triiodothyronine-binding autoantibodies.

Between 1982 and 1989 we identified 47 subjects with spuriously increased concentrations of free thyroxin (FT4) or free triiodothyronine (FT3) related to autoantibody interference in analog FT4 and (or) FT3 methods. The incidence of autoantibody interference observed during one year (1988) was 1 in 2460. In the subjects identified, 51% and 11%, respectively, showed an increased binding of radiolabeled T4 or T3 analog alone; 38% had an increased binding of both. Of 36 patients tested, 71% had autoantibodies to thyroglobulin and microsomal fraction of the thyroid, 19% to microsomal fraction alone, and 9.5% to thyroglobulin alone. In eight subjects, spuriously increased FT4 concentrations were reported with the following FT4 methods (in decreasing order of interference): Coat-A-Count, Amerlex-M, Amerlite, Seria, Magic Lite, Amerlex-MAB. In the same eight subjects, Amerlex-M and Seria reported spuriously increased concentrations of FT3.

Adolescent↗
PubMed1989

Antibody interference in a two-site immunometric assay for thyrotrophin.

Of 1585 consecutive serum samples referred for thyroid function testing, 14 gave erroneously high values from a two-site immunoenzymometric assay for thyrotrophin. The addition of mouse or newborn calf serum to the assay failed to correct the interference. In serum samples from 11 patients who were available for follow up a higher concentration of mouse, but not of horse, sheep or rabbit serum reduced the interference. The interference was associated only with assay systems which employed horseradish peroxidase but not 125I as a label. Addition of mouse serum and anti-IgM to the assay reagents successfully removed the interference.

Animals↗
PubMed1988

Evaluation of a new strategy for detection of thyroid dysfunction in the routine laboratory.

We assessed the use of a new strategy for detecting thyroid disorders, utilizing a sensitive assay for concentrations of thyrotropin (TSH) and free thyroid hormone in serum as follow-up tests. Of 1279 patients who were not on thyroxin (T4) replacement treatment, 82% could be classified as euthyroid and would require no further tests. In patients who were on T4 replacement, 41% fell into the euthyroid category and would require no further tests. Using this strategy to replace our existing strategy of free thyroxin as a "first-line" test would reduce the proportion of patients who would require one or more follow-up tests from 49% to 24%.

Evaluation Studies as Topic↗
PubMed1987

Chemiluminescence in the presence of ferritin.

The ability of ferritins with differing iron contents to catalyze the oxidation of luminol by hydrogen peroxide was studied. The least efficient catalysts were iron-rich ferritins, and the most potent were those with iron to protein ratios of less than 0.1.

Catalysis↗
PubMed1987

An enhanced serum prolactin response to TRH in the presence of GABA transaminase inhibition.

Patients with epilepsy were found to have an increased 20 minute prolactin response to intravenous TRH stimulation when receiving the GABA-T inhibiting drug vigabatrin. Enhanced GABA activity may either reduce basal prolactin levels whilst allowing a normal pituitary response to TRH stimulation, or may overcome the inhibitory effects of dopamine on pituitary prolactin release.

4-Aminobutyrate Transaminase↗
PubMed1986

Evaluation of an enhanced luminescence assay for alpha-fetoprotein.

We evaluated a two-site enhanced luminescence immunoenzymometric assay (Amerlite; Amersham International) for alpha-fetoprotein (AFP) in maternal serum and amniotic fluid. The assay is rapid, involving two incubations totalling 4 h. The working range of the assay for serum AFP is 5.5 to 750 kilo-int. units/L (CV less than 10%), with a sensitivity of detection of 0.2 kilo-int. unit/L. The regression equation for the Amerlite assay (y) and our in-house RIA procedure (x) was y = 0.816x + 2.9 (n = 142, r = 0.96). Analytical recovery of added AFP (code 72/227) at three concentrations was 86.7%. Serum AFP concentrations were measured at 15 to 18 weeks of gestation in subjects with normal pregnancies and in subjects whose pregnancies resulted in open neural tube defects; all of the latter had serum AFP concentrations greater than 2.5 multiples of the median. We find the Amerlite system to be an efficient, reliable system for screening for open neural tube defects without use of hazardous radioactive labels.

Amniotic Fluid↗
PubMed1986

Enhanced luminescence immunoassay: evaluation of a new, more sensitive thyrotropin assay.

We measured thyrotropin (TSH) with an enhanced luminometric assay ("Amerlite"; Amersham International). The detection limit of the assay is 0.02 milli-int. unit/L. Within-assay precision was 6.7 and 7.8% at 3.77 and 12.1 milli-int units/L, respectively, and between-assay precision was almost identical, whether singleton or duplicate samples were assayed. TSH measured in 132 euthyroid subjects ranged from 0.06 to 4.13 milli-int. units/L (mean 1.52, SD 0.86). Similar concentrations were found in 20 healthy pregnant women and 19 of 20 healthy post-menopausal women (one of whom had undetectable TSH). In 17 patients with primary hypothyroidism, TSH concentrations ranged from 9.34 to greater than 200 milli-int. units/L; and in 53 of 59 patients with hyperthyroidism, TSH concentrations were undetectable, ranging in the remaining six from 0.03 to 0.06 milli-int. unit/L. Results for TSH in 28 patients stimulated with thyroliberin were consonant with the results of the thyroliberin test in 25 cases. Thus, for most patients, measurement of a basal TSH concentration evidently will predict their thyroidal status and also the response to thyroliberin, but a few will require additional tests of thyroid function.

Adolescent↗