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Biomedical subjects

B Byrne

Publications and source records attributed to B Byrne.

At least 19 recordsLinked to original sources
PubMed1995

Gonadotropin surge-attenuating factor bioactivity in serum from superovulated women is not blocked by inhibin antibody.

Primary pituitary cultures from adult female rats were used to investigate gonadotropin surge attenuating factor (GnSAF) bioactivity. Serum from superovulated women was charcoal-treated and incubated with either an inhibin antibody (MC4), normal sheep serum (NSS), or serum-free defined medium (SFDM) before addition to cell culture. The reduction in GnRH-induced LH secretion (GnSAF bioactivity) produced by the serum (30.1 +/- 6.5%, p < 0.001, of control) was not altered by prior incubation with either MC4 or NSS (24.9 +/- 3.6 and 23.2 +/- 2.7%, p < 0.001, of control, respectively). This indicates that GnSAF bioactivity present in serum from superovulated women is not entirely attributable to inhibin. Recombinant human inhibin reduced basal FSH secretion to 24.6 +/- 4.7% (p < 0.001) of the control value. However, this was totally abolished by prior incubation with MC4, but not NSS. We have also shown that ovarian steroids are not responsible for GnSAF bioactivity in vitro. In conclusion, in contrast to findings in superovulated rats, inhibin antibody did not block GnSAF bioactivity in serum from superovulated women.

Animals↗
PubMed1994

Higher gonadotrophin surge-attenuating factor bioactivity is found in small follicles from superovulated women.

Ovine and rat pituitary bioassays for gonadotrophin surge-attenuating factor (GnSAF) were utilized to determine whether the level of GnSAF bioactivity in pooled human follicular fluid (hFF) from superovulated women varied according to follicle diameter (< or = 11 mm, 12-15 mm and 16-21 mm follicles examined using the ovine bioassay, or < or = 10 mm, 11-13 mm, 14-17 mm, 18-20 mm, 21-24 mm and > or = 25 mm follicles examined using the rat bioassay). When tested using dispersed ovine pituitary cells, GnSAF bioactivity, expressed in terms of the reduction in gonadotrophin-releasing hormone (GnRH)-induced LH secretion, was inversely related to follicle diameter (P < 0.01). In response to 5 microliters hFF/well from follicles of < or = 11, 12-15 and 16-21 mm diameter, GnRH-induced LH secretion was reduced to 40.5 +/- 6.9%, 65.2 +/- 6.6% and 83.7 +/- 7.9% of control respectively. A similar inverse relationship was observed when a second batch of hFF samples from different sized follicles was tested using rat pituitary cell monolayers. Expressing GnSAF bioactivity in terms of the dose required to suppress GnRH-induced LH secretion by rat pituitary cells to 50% of the maximal suppression observed (ED50), the three smallest follicle size pools contained the most GnSAF (ED50 values of 0.13, 2.79 and 5.36 microliters hFF/well from follicles of < or = 10, 11-13 and 14-17 mm respectively). The ED50 values for follicles of 18-20, 21-24 and > or = 25 mm were 8.81, 27.1 and 60.0 microliters hFF/well respectively. Thus hFF from follicles < or = 11 mm was over 450 times more potent than hFF from follicles > or = 25 mm in suppressing GnRH-induced LH release. The ED50 values for inhibin bioactivity (measured as the suppression of basal FSH secretion from rat pituitary monolayers) were much less variable than those for GnSAF bioactivity (between 0.85 and 0.13 microliters hFF/well). Inhibin immunoreactivity, measured by a two-site immunoradiometric assay, followed the same pattern as inhibin bioactivity with lowest concentrations in the smallest follicles (41.96 ng/ml) and highest concentrations in the three largest follicle size groups (56.48-64.48 ng/ml). The specific effects of inhibin on GnRH-induced LH and basal FSH release in these pituitary bioassays were determined by incubating culture dishes with pure recombinant human inhibin at doses of 0.025-25 ng/well. In both the sheep and rat pituitary monolayers, basal FSH was suppressed (ED50 = 0.02 and 0.16 ng/well respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Circulating gonadotrophin surge-attenuating factor from superovulated women suppresses in vitro gonadotrophin-releasing hormone self-priming.

A perifusion system based on ovine pituitary tissue explants was used to investigate the effects of follicular fluid (hFF) and serum from superovulated women on pituitary responsiveness to gonadotrophin-releasing hormone (GnRH). The specific aims of the study were to determine both if gonadotrophin surge-attenuating factor (GnSAF) bioactivity is present in the peripheral circulation as well as in the follicles of superovulated women and if GnSAF suppresses GnRH self-priming in vitro. Two pulses of GnRH, 1 h apart, produced marked peaks in LH secreted from control chambers, with GnRH self-priming evident in the significant difference between the first (134.4 +/- 1.7 - 232.1 +/- 24.0% of basal secretion) and second (183.9 +/- 15.8 - 313.9 +/- 14.0% of basal secretion) LH peaks. Both follicular fluid and serum pooled from two different groups of women produced marked suppression of the first (unprimed) and second (primed) LH peaks. The hFF reduced the first LH peak to 69.6 +/- 7.8 and 60.2 +/- 9.7% and the second LH peak to 57.4 +/- 6.7 and 42.6 +/- 6.5% of control LH secretion. Overall, the serum reduced the first and second LH peaks to 76.8 +/- 4.2 and 62.9 +/- 3.6% of control respectively. These results demonstrated that GnSAF bioactivity suppresses GnRH self-priming, and is present in both the peripheral circulation and hFF. The same material administered to dispersed ovine pituitary monolayers produced similar marked suppression of GnRH-induced LH secretion, with approximately 50-fold less GnSAF bioactivity in serum compared with hFF. Combined doses of oestradiol and progesterone, or hFF from large follicles containing little GnSAF, produced stimulation of GnRH-induced LH secretion and GnRH self-priming (second peaks 78.1 +/- 38.9 and 27.4 +/- 15.7% respectively higher than first peaks). Thus, in conclusion, GnSAF in hFF and serum markedly attenuated both unprimed and primed pituitary response to GnRH, virtually abolishing the GnRH self-priming effect.

Animals↗
PubMed1991

Effects of green or white light for treatment of seasonal depression.

Twelve subjects with winter depression were treated with equal quanta of green or white light in a randomized crossover study. Each treatment condition consisted of 2 hours of exposure each morning for 1 week, with at least 1 interventing week without treatment. Ratings made without knowledge of treatment condition were done before and after each condition. Both treatments significantly reduced depression ratings. White light was significantly more effective than green light in reducing endogenous symptoms, but not the "atypical" symptoms that are common features of winter depression. Furthermore, sequence of treatment conditions influenced antidepressant responses. Broad-band white light may be optimal for maximizing therapeutic response.

Adult↗
PubMed1991

Sex steroids, adiposity and smoking in the pathogenesis of idiopathic hirsutism and polycystic ovary syndrome.

Hyperestronemia may be central to the development of polycystic ovary syndrome. The present study was designed to examine whether increased availability of androstenedione or increased aromatase closely associated with adiposity, plays the dominant role in the development of hyperestronemia. We measured plasma androstenedione, estrone and the estrone/androstenedione ratio (an indirect index of peripheral aromatase activity), in 141 patients with idiopathic hirsutism and in 88 patients with polycystic ovary syndrome. Estrone levels were higher in polycystic ovary syndrome, 250.4 +/- 129 (mean +/- standard deviation) than in idiopathic hirsutism, 210.6 +/- 119 pmol/l, p less than 0.05. Plasma androstenedione levels were higher in polycystic ovary syndrome, 8.24 +/- 3.5, than in idiopathic hirsutism, 7.1 +/- 1.7 nmol/l, p less than 0.0025. However, the estrone/androstenedione ratio was similar in the two groups. In all patients who smoked, androstenedione was higher, 8.14 +/- 3.22 than in nonsmokers, 6.99 +/- 2.96 nmol/l, p less than 0.005. Smokers had a lower body mass index, 23.9 +/- 2.3, than non-smokers 25.6 +/- 4.8 kg/m2, p less than 0.025. However, estrone levels were similar in smokers and in non-smokers. These data indicate that elevated estrone is more closely related to increased availability of androstenedione than to increased aromatase activity. While cigarette smoking appears to increase androstenedione levels, it may inhibit aromatase activity either directly or indirectly because of an associated reduction in adiposity. However, since the relative frequency of polycystic ovary syndrome and idiopathic hirsutism was similar in smokers and non-smokers, smoking did not appear to reduce estrone bioactivity as had been claimed.

Adrenal Glands↗
PubMed1990

Light-induced plasma melatonin suppression in seasonal affective disorder.

1. Subjects with seasonal affective disorder were exposed to 0, 500 and 1000 lux of white light for one hour beginning at 0300 hours. 2. Plasma samples were taken periodically and analysed for melatonin. 3. Plasma melatonin levels were suppressed by exposure to both 500 and 1000 lux light levels, suggesting that SAD patients show no neuroendocrine insensitivity to light but may show supersensitive responses to light.

Female↗
PubMed1990

Treatment of winter depression with a portable, head-mounted phototherapy device.

1. A portable, head-mounted device was developed for administration of light therapy. A randomized crossover protocol was used to test the therapeutic efficacy of this device, compared to a standard light box, for treatment of winter depression. 2. Depressive symptoms were significantly reduced by both the head-mounted device and the light box. 3. Therapeutic efficacy of the two devices was not significantly different. 4. The head-mounted device was rated by patients as significantly more convenient than the conventional light box; this may be important in improving patient compliance.

Adult↗
PubMed1989

Learning artificial orthographies: further evidence of a nonanalytic acquisition procedure.

Previous research (Byrne, 1984) showed that adults who learned to read an orthography representing phonetic features (voicing, place of articulation) did not readily obtain usable knowledge of the mapping of phonetic features onto orthographic elements, as evidenced by failure to generalize to partially new stimuli. The present Experiment 1 used a different method of detecting learning savings during acquisition. Subjects learned a set of complex symbols standing for phones, with the elements representing voicing and place. In a second acquisition set, the signs for voicing were reversed. Learning speed was not affected, which was consistent with the claim that feature-element links went unnoticed in initial acquisition. In Experiment 2, some subjects were instructed to "find the rule" embodied in the orthography. None did, and acquisition rates were no different from those of uninstructed subjects. In Experiment 3, subjects had 4 h of training on the orthography, with consistent feature-symbol mapping for half of the subjects and arbitrary pairings for the remainder. No reaction time advantage emerged in the consistent condition, which is further evidence of nonanalytic acquisition. The results are related to data from children learning to read.

Cues↗
PubMed1988

Effects of routine pupillary dilation on functional daylight vision.

The visual acuity of 100 patients between the ages of 16 and 66 years, seen for routine ophthalmologic examination, was measured before and after dilation. All patients had a predilation visual acuity of 20/40 or better. Postdilation binocular visual acuity using the patients' usual correction was measured first in the office and then outdoors, both with the patient's back to and the patient facing the sun, with and without the aid of postmydriatic sunglasses. Twelve percent experienced disabling photophobia even with the use of postmydriatic sunglasses, with 3% having significant objective visual loss defined as 20/50 or worse. No objective visual loss was found in 30 controls examined outdoors before dilation, without sunglasses. We recommend that patients who have experienced significant photophobia with dilation in the past, or who have never before undergone dilation, make arrangements for transportation after a dilated examination.

Adolescent↗
PubMed1988

Anti-human immunodeficiency virus type 1 antibody complexes on platelets of seropositive thrombocytopenic homosexuals and narcotic addicts.

Patients with human immunodeficiency virus type 1 (HIV-1) infection develop an immunologic thrombocytopenic purpura associated with markedly elevated platelet IgG, IgM, and C3C4 as well as serum immune complexes determined by the polyethylene glycol (PEG) method. Analysis of their serum PEG-precipitable immune complexes as well as platelet acid eluates revealed the presence of anti-HIV-1 antibody existing as a complex that eluted in the void volume of a Sephadex G-200 gel-filtration column. The complex binds to washed normal platelets, whereas affinity-purified anti-HIV-1 (gp120) antibody does not. HIV-1 antigen or proviral DNA was not detectable in the immune complexes or platelet extracts. However, anti-antibodies directed against anti-HIV-1 antibody were detectable in the immune complexes as well as platelet eluates. Approximately 50% of eluted platelet IgG contained anti-HIV-1 antibody. Thus the markedly elevated platelet immunoglobulin is partly due to the presence of anti-HIV-1 antibody complexes. This may be responsible for the enhanced platelet clearance and thrombocytopenia in patients with acquired immunodeficiency syndrome-related immunologic thrombocytopenia.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Extraocular muscle size comparison using standardized A-scan echography and computerized tomography scan measurements.

In many clinical situations, the standard for evaluating extraocular muscle (EOM) size, particularly in thyroid ophthalmopathy, has been use of the computerized tomography (CT) scanner. The impression is generally reported as "enlarged or normal EOMs." If the report of "normal EOM" on CT scan weighs heavily against the diagnosis of thyroid eye disease, how does this qualitative assessment compare with the diagnostic modality of ultrasound? The technique of standardized A-scan measurement of extraocular muscles has been extremely accurate. In this paper, standardized A-scan measurements and CT scan estimates of EOMs are compared in a series of ten patients with a clinical diagnosis of Graves' disease. Three of ten patients displayed enlarged EOMs by CT interpretations; seven of ten patients were categorized as consistent with Graves' disease by correlation with current ultrasonographic criteria for muscle enlargement, asymmetry, and high irregularity of tissue reflectivity.

Exophthalmos↗