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Biomedical subjects

A S Brown

Publications and source records attributed to A S Brown.

At least 19 recordsLinked to original sources
PubMed1992

Insulin-like growth factor-1, growth hormone-dependent insulin-like growth factor-binding protein and growth in children with chronic renal failure.

Insulin-like growth factor-binding protein-3 (IGFBP-3) and insulin-like growth factor-1 (IGF-1) levels were measured by specific radioimmunoassays in children with all degrees of chronic renal failure (CRF). Study group 1 comprised 29 children (10 on dialysis) who had been studied one to four times over 2 years to determine whether IGF-1 and IGFBP-3 levels differed from those in age-matched healthy children and to examine the relationship between these levels and heights. IGF-1 and IGFBP-3 levels did not differ from those in normal children. IGF-1 and IGFBP-3 were significantly correlated, increased with pubertal stage in all children and with age in non-dialysis patients. IGF-1, but not IGFBP-3, correlated with age in dialysis patients. There was no correlation between IGF-1 or IGFBP-3 levels (corrected for age) and height standard deviation score (SDS) in either non-dialysis or dialysis patients. Study group 2 comprised 19 children (7 on dialysis) who were studied prospectively for 1-2 years to examine the relationship between IGF-1 and IGFBP-3 levels, growth rates and nutritional parameters. Mean values of IGF-1 and IGFBP-3 (corrected for age) did not change over 1-year periods, while height SDS fell by -0.38 +/- 0.21 SD/year in dialysis patients and by -0.11 +/- 0.29 SD/year in non-dialysis patients. No significant correlations were found between IGF-1 or IGFBP-3 levels and growth rates or nutritional parameters. Thus growth retardation in children with CRF is not related to circulating levels of IGF-1 or IGFBP-3.

Adolescent↗
PubMed1992

Endozepine/diazepam binding inhibitor in adrenocortical and Leydig cell lines: absence of hormonal regulation.

One of the many effects which have been attributed to the peptide endozepine/diazepam binding inhibitor (Ep/DBI) is the stimulation of adrenocortical and testicular Leydig cell mitochondrial steroidogenesis. We have used two cell lines (Y-1 mouse adrenal cell tumour and MA-10 mouse Leydig cell tumour), both of which exhibit hormone stimulated steroid production, to investigate the role of Ep/DBI in acute hormone stimulated steroidogenesis. The time course of incorporation of 35S-translabel into Ep/DBI and its turnover rate when the isotope was removed were examined. Cell samples were extracted and separated on Sep-Pak C18 columns and analysed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analysis followed by fluorography as well as by direct scintillation counting. This allowed us to estimate the in vivo half-life of Ep/DBI and also to investigate the hormonal dependence of the peptide. Data presented here suggest that (i) Ep/DBI levels are not regulated by trophic hormones in these steroidogenic cell lines, and (ii) that the peptide has a relatively long half-life (greater than 3 h), a finding incompatible with suggestions of it having a rapid turnover. Therefore, it seems unlikely that control of Ep/DBI steroidogenic effects is via hormonal modulation of the peptide levels.

Adrenal Cortex↗
PubMed1992

Ophthalmologic examination of the normal eye of the koala.

The ophthalmic examination of the koala (Phascolarctos cinereus) was undertaken to describe the normal in vivo structure. Twenty-two of 28 koalas examined were found to have normal eyes. Slit-lamp examination revealed unusual lamellae in the cornea, and mean keratometric readings were 59.3 +/- 3 diopters, corneal endothelial cell area of 381.4 microns2 +/- with a standard deviation of 46.8 microns2. No particular features were seen which would explain the susceptibility of this animal to ocular infection by Chlamydia psittaci.

Animals↗
PubMed1992

Keratitis in free-ranging koalas (Phascolarctos cinereus) on Magnetic Island, Townsville.

Seventy free-ranging koalas (Phascolarctos cinereus) from Magnetic Island (Queensland, Australia) underwent an ocular examination, blood collection and serological examination for Chlamydia psittaci antibodies, and an examination of their teeth and genitalia. In 12 koalas long-standing unilateral keratitis was noted and in another 10 animals long-standing bilateral keratitis was observed. All animals were seronegative for Chlamydia psittaci and apart from some nasal discharge and a variety of assorted medical findings there was no sign of chlamydial infection. These ocular findings probably represent a new disease of unknown etiology.

Animals↗
PubMed1992

Is routine cervical spine radiographic evaluation indicated in patients with mandibular fractures?

Fractures of the mandible are commonly seen in most urban trauma centers. Over the past decade, the authors have seen a rise in these injuries secondary to an increase in drug and alcohol abuse, violent crime, and high-speed motor vehicle accidents. Several reports have described an association between mandibular fractures and cervical spine injuries and recommend routine cervical spine radiographs in all patients with mandibular injuries. These studies have failed to show a "cause and effect" relationship because of concomitant injuries found in these patients. This study reviews mandibular fractures and cervical spine injury retrospectively and prospectively over a 3-year period. The retrospective study included patients with isolated mandibular fractures who came to Cooper Hospital/University Medical Center Emergency Room in 1987. Thirty patients were identified, 18 of whom had cervical spine x rays. No patients had a significant radiologic or clinical cervical spine injury. The prospective study included all patients with mandibular fractures seen in the emergency room during 1988 and 1989. Seventy-three patients were identified, 44 of whom had mandibular and cervical spine radiographs. None had a significant radiologic or clinical cervical spine injury. The authors conclude that routine cervical spine x rays are costly and unnecessary. Also, any patient with a suspicion of concomitant cervical spine injury (i.e., patients with a loss of consciousness, multi-organ system injury, cervical pain or tenderness, or intoxication from alcohol use) should have cervical spine x rays, including anteroposterior, lateral, and open-mouth odontoid views.

Academic Medical Centers↗
PubMed1991

Recanalization of chronically occluded aortocoronary saphenous vein bypass grafts by extended infusion of urokinase: initial results and short-term clinical follow-up.

Chronic occlusion of saphenous vein aortocoronary bypass grafts is a common problem. Although percutaneous transluminal angioplasty of a saphenous vein with a stenotic lesion is feasible, angioplasty alone of a totally occluded vein graft yields uniformly poor results. Patients with such occlusion are often subjected to repeat aortocoronary bypass surgery. Experience with a new technique that allows angioplasty to be performed in a totally occluded saphenous vein bypass graft is reported. This technique utilizes infusion of prolonged low dose urokinase directly into the proximal portion of the occluded graft. Forty-six consecutive patients with 47 totally occluded grafts were studied. Patients had undergone end to side saphenous vein bypass grafting 1 to 13 (mean 7) years previously. All patients presented with new or worsening angina pectoris with ST-T changes or non-Q wave acute myocardial infarction and all had a totally occluded saphenous vein bypass graft. The new technique entailed the positioning of an angiographic catheter into the stub of the occluded graft and the advancement of an infusion wire into the graft. Patients were returned to the coronary care unit, where urokinase was delivered at a dose of 100,000 to 250,000 U/h. The total dose of urokinase ranged from 0.7 to 9.8 million U over 7.5 to 77 h (mean 31). After therapy, recanalization was seen in 37 (79%) of the 47 grafts. In 20 successfully treated patients, angiography was performed 1 to 24 (mean 11) months after treatment; 13 (65%) of these grafts were patent.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Stimulation by endozepine of the side-chain cleavage of cholesterol in a reconstituted enzyme system.

Addition of endozepine in nanomolar concentrations to a system for side-chain cleavage reconstituted from highly purified P-450scc and electron carriers (adrenodoxin reductase and adrenodoxin) stimulates the conversion of cholesterol to pregnenolone (side-chain cleavage). This response is concentration and time-dependent and specific to the extent that a second steroidogenic P-450 located in the inner mitochondrial membrane (ie 11 beta-hydroxylase) was not stimulated by endozepine. Homogeneous endozepine prepared from bovine brain, the corresponding genetically engineered peptide and des(glu-ilu)-endozepine isolated from bovine adrenal cortex are all approximately equipotent in this system. Moreover, endozepine accelerates the rate of reduction of P-450scc by NADPH and the electron carriers. The results suggest that endozepine acts directly on P-450 and hence the rate of side-chain cleavage.

Adrenal Cortex↗
PubMed1991

Transfer of processing in repetition priming: some inappropriate findings.

Transfer effects in repetition priming were found with both picture and word naming, but varied with the type of prime list. Unmixed lists of word or picture primes produced equivalent intra-modal and cross-modal repetition priming in both picture-naming (Experiment 1) and word-naming (Experiment 5) tasks. However, mixing word and picture primes resulted in greater intra-modal than cross-modal priming for both picture-naming (Experiment 2) and word-naming (Experiment 6) tasks. This mixed-list difference between intra-modal and cross-modal priming was reduced by blocking prime types at input (Experiment 3). These findings suggest that differences in priming as a function of prime stimulus format should be cautiously interpreted when mixed prime lists are used.

Adult↗
PubMed1991

Age differences in retrieval consistency and response dominance.

The probability of generating dominant responses and producing the same response on two occasions was compared for older and younger adults over three different intervals. Continuous retrieval from broadly defined semantic and orthographic categories was examined in Experiment 1; single-word retrieval from restricted categories was tested in Experiment 2 using a picture-naming task. There was no age difference in the tendency to generate normatively dominant responses in either experiment, but there were age differences in consistency. For broad categories, older were less consistent than younger adults at each intersession interval. With restricted categories, older adults showed a systematic decline in consistency over increasing intersession interval, while younger adults showed no change. Unlike prior research, we failed to find evidence for a positive relationship between verbal ability and response dominance.

Adolescent↗
PubMed1979

Decrease in serum receptor-reactive somatomedin in diabetes.

Somatomedin in rat serum has been measured by a sensitive radioreceptor assay using 125I-labelled human somatomedin and human placental membrane. In rats made diabetic with strepotzotocin, receptor-reactive somatomedin levels were decrease by up to 75%. The decrease followed the time course of increasing serum glucose and occurred to the same extent in rats aged between 4 and 40 weeks. Endogenous serum receptor-reactive somatomedin appeared exclusively in high molecular weight fractions on gel chromatography. In diabetes the decreased somatomedin was due to a fall in this high molecular weight activity, but was not accompanied by a fall in somatomedin binding protein. These results suggest a role for insulin in maintaining serum somatomedin levels.

Animals↗
PubMed1979

Skin necrosis from extravasation of intravenous fluids in children.

From 16,380 administrations of I.V. fluid in children during a 6-month period, there were 1,800 extravasations (11%) with 40 skin sloughs. All that resulted in either partial or full-thickness skin loss were treated by one of 3 conservative protocols, and no skin grafts were needed in this series. Most of the extravasations resulting in skin loss were associated with hypertonic fluids and the use of infusion pumps. Careful hourly monitoring of such cases seems highly desirable. We found no discernible differences in the healing among the 3 treatment regimens used. The importance of systematic monitoring of children receiving I.V. fluids by nursing personnel, the elevation of an extremity involved in an extravasation, and the care of any resulting wounds are discussed.

Child↗
PubMed1978

Serum fucose as a monitor for recurrent malignancy.

Serum fucose determinations were performed on 19 patients with "stable" or "inactive" malignancies, 33 patients with "active" malignancies, and 14 "normals." A significant difference in the values between "normal" and "stable" patients and those with "active" cancer is shown. A role for this relatively simple serological test for diagnosing and following metastatic cancer is suggested.

Adult↗
PubMed1977

Properties and N-terminal sequence of allophycocyanin from the unicellular rhodophyte Cyanidium caldarium.

Allophycocyanin from the unicellular rhodophyte Cyanidium caldarium was purified by (NH4)2SO4 fractionation and ion-exchange chromatography on brushite (calcium phosphate) columns and on DEAE-Sephadex A-25 columns. The specific absorption coefficient (A0.1%1cm) at 650nm of purified allophycocyanin was 6.35 in 0.05M-potassium phosphate buffer, pH7.0. Absorption maxima of allophycocyanin occurred at 650, 618 (shoulder), 350 and 275 nm. Circular-dichroic spectra displayed positive-ellipticity bands at 658 and 630 nm and a major negative-ellipticity band at 340nm. Computer analysis of the circular-dichroic spectrum of allophycocyanin from 207 to 243 nm indicated 42% alpha-helix and 58% beta-form. The estimated molecular weight of purified allophycocyanin on calibrated Sephadex G-200 columns at pH7.0. was 196000. Electrophoretic examination of allophycocyanin on sodium dodecyl sulphate/polyacrylamide gels revealed a single band with apparent mol.wt. 16000. The presence of two polypeptide subunits, with nearly the same molecular weight, was revealed on polyacrylamide gels by using a modified electrophoresis buffer. Spectral analysis of the allophycocyanin subunits resolved by ion-exchange chromatography on Bio-Rex 70 columns indicated that a single phycocyanobilin chromophore was present on each polypeptide chain. Treatment of allophycocyanin with 8M-urea (pH3.0) and subsequent removal of urea by dialysis against water yielded a derivative phycobiliprotein with spectroscopic characteristics similar to those of phycocyanin. The original allophycocyanin spectrum was regenerated after incubation in phosphate buffer, pH7.0. Automated sequences analysis of the N-terminus of allophycocyanin showed that (a) the sequences of the two subunits were different from one another and were different from the subunits of phycocyanin from the same alga, (b) the subunits occurred in a molar ratio of 1:1 and (c) the sequences homology at the N-terminus among alpha- and beta-subunits of allophycocyanin from blue-green and red algae approached 90%.

Amino Acid Sequence↗