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Biomedical subjects

S Green

Publications and source records attributed to S Green.

At least 379 records · Page 21Linked to original sources
PubMed1987

A guide for mutagenicity testing using the dominant lethal assay.

The dominant lethal assay has been used and continues to be used to provide information about the effects of chemicals on the gonadal cells of male animals. Guidelines for conducting this test are useful but as with any guideline scientists should avoid interpreting them as protocols. Thus this document is a general approach to dominant lethal testing and should be used in conjunction with other available protocols and procedures.

Animals↗
PubMed1987

Digestibilities of amino acids in maize, wheat and barley meals, determined with intact and caecectomised cockerels.

1. Maize, wheat and barley meals, and a protein-free diet were each force-fed to 24 intact and 24 caecectomised adult cockerels. For each test, birds were starved of solid food for 48 h, fed, and then excreta collected for 48 h. 2. Quantities of nitrogen (N) and amino acids excreted after feeding the protein-free diet did not differ between intact and caecectomised birds. 3. True digestibility coefficients of N and amino acids did not differ between intact and caecectomised birds. 4. Differences between cereals in apparent digestibility of amino acids were inconsistent and more readily attributed to differences between amino acid intake than bioavailability. 5. Differences between cereals in true digestibility of amino acids were confined to higher values for N, aspartic acid, alanine and leucine in maize than in barley or wheat meals.

Amino Acids↗
PubMed1987

Digestibilities of amino acids in soyabean, sunflower and groundnut meals, determined with intact and caecectomised cockerels.

1. Three isonitrogenous diets were formulated in which soyabean (dehulled), sunflower (hulled) and groundnut (dehulled) meals were the sole protein sources. 2. 50 g of each diet was tube-fed to each of 24 intact and 24 caecectomised cockerels, which had been previously starved for 48 h. Excreta were collected, individually, for 48 h. The concentrations of amino acids in the diets and excreta were determined, and digestibility coefficients calculated. 3. Differences between intact and caecectomised birds for true digestibility evaluations reached significance for threonine, glycine and lysine only. Deamination of threonine and glycine, and synthesis of lysine, in the caeca was implied. 4. Neither the true digestibility of nitrogen, nor that of the sum of the amino acids differed between protein sources. 5. True digestibilities of most essential amino acids, considered individually, in sunflower and groundnut meals were similar to or greater than, those of soyabean meal. Exceptionally, lysine was more digestible in soyabean (0.879) than in sunflower (0.722) or groundnut (0.788) meals.

Amino Acids↗
PubMed1987

Collisional excitation of interstellar cyclopropenylidene.

Theoretical rotational excitation rates were computed for C3H2 in collisions with He atoms at temperatures from 30 to 120 K. The intermolecular forces were obtained from accurate self-consistent field and perturbation theory calculations, and collision dynamics were treated within the infinite-order sudden approximation. The accuracy of the latter was examined by comparing with the more exact coupled states approximation.

Astronomical Phenomena↗
PubMed1987

Ipratropium bromide and airways function in wheezy infants.

The airway response to nebulised ipratropium bromide was studied in 17 chronically or recurrently wheezy infants aged 4-15 months. The peripheral airway response was assessed by the change in maximum flow at functional residual capacity (Vmax FRC) and the upper and central airway response by the change in specific airways resistance. The significant reduction in specific airways resistance after treatment with ipratropium bromide signified an improvement in central and upper airway function. No change was found, however, in Vmax FRC and hence in peripheral airway function. It seems that, as in older subjects, inhaled antimuscarinic, anticholinergic drugs have their maximum effect on the large airways, and this may explain their lack of effect in the management of acute bronchiolitis.

Airway Resistance↗
PubMed1987

Airway responsiveness in wheezy infants: evidence for functional beta adrenergic receptors.

The effect of nebulised salbutamol on the bronchial response to nebulised histamine was studied in five wheezy infants aged 3-12 months. The response to doubling concentrations of up to 8 g/l of histamine was assessed by the change in the maximum flow at FRC (VmaxFRC), measured by flow-volume curves produced during forced expiration with a pressure jacket. The concentration of histamine required to provoke a 30% fall in VmaxFRC (PC30) was measured. All of the infants responded to low concentrations of histamine during control tests before and after nebulised saline (mean PC30 1.07 and 0.51 g/l). On a separate day there was a similar response to histamine before salbutamol (PC30 0.57 g/l), but after salbutamol the response was completely abolished up to the maximum concentration of histamine in all subjects (PC30 greater than 8 g/l). Thus wheezy infants have highly effective beta 2 adrenoceptors in intrathoracic airways.

Albuterol↗
PubMed1987

Paradoxical response to nebulised salbutamol in wheezy infants, assessed by partial expiratory flow-volume curves.

Lower airway responses to nebulised bronchodilators were studied in 18 chronically or recurrently wheezy infants, aged 3-15 months, by means of partial forced expiratory flow-volume manoeuvres performed with an inflatable jacket. Maximum flow at functional residual capacity (FRC) (VmaxFRC) was used as the index of intrathoracic airways function. Peak expiratory flow rate was also measured. Baseline airways resistance and lung volume were determined during quiet breathing in an infant whole body plethysmograph. Measurements were made on separate days before and after nebulised salbutamol 2.5 mg with nebulised saline as control. The results were paradoxical: there was no change in VmaxFRC after saline, but a significant decline in VmaxFRC was found after salbutamol. Peak expiratory flow remained unchanged. These observations suggest that under conditions of forced expiration intrathoracic airways function may be further impaired by nebulised bronchodilator treatment in wheezy infants. When nebulised bronchodilator drugs are used to treat severe airways obstruction in infancy, careful monitoring is essential.

Airway Resistance↗
PubMed1987

Bronchial responsiveness to histamine in wheezy infants.

Little is known about airway responsiveness in infancy. The bronchial response to incremental doses of nebulised histamine (to a maximum dose of 8 g/l) was measured in 11 wheezy infants with a mean age of 8.7 months. The study was repeated after a 30-40 minute recovery period in seven infants and again on a separate day in 10. The index of response was the provoking concentration of histamine that produced a 30% fall in the maximum expiratory flow at functional residual capacity (PC30), taken from partial forced expiratory flow-volume curves produced in a pressure jacket. Nine of 11 infants had a PC30 of less than 8 g/l. The response was consistent between tests in both the nine responders and the two who failed to respond at 8 g/l. The PC30 was lower in infants with more severe baseline airway obstruction. Spontaneous recovery after challenge was complete in 30 minutes in seven of eight infants studied. The highest doses of histamine caused changes in the configuration of the flow-volume curves and symptomatic cough and wheeze in addition to a change in forced flow rates. This study provides clear evidence of intrathoracic airway responsiveness to histamine in infancy.

Bronchi↗
PubMed1987

Duration of protection by oxitropium bromide against cholinergic challenge.

In order to determine the duration of action of the inhaled anticholinergic agent oxitropium bromide, a controlled study of the effect of pre-treatment with oxitropium bromide 200 micrograms against cholinergic challenge was carried out in ten asthmatic subjects (6 children, 4 adults). After baseline measurements of lung function (FEV1 and sGaw) and methacholine PC20 (the concentration of methacholine to produce a 20% fall in FEV1) oxitropium bromide or placebo were inhaled double-blind on 2 separate days. Lung function and methacholine PC20 were then measured at 1, 3 and 6 h post dosing. Oxitropium bromide caused significant protection from methacholine challenge for 6 h (p less than 0.05).

Adolescent↗
PubMed1987

Effect of viscoelastic insoles on pain.

The purpose of this study was to assess the effect of viscoelastic shoe inserts on pain in nursing students. Students (N = 100) were randomly assigned to control and viscoelastic groups. The viscoelastic group used viscoelastic insoles in their work shoes for five weeks. A pain questionnaire was used to measure location and intensity of post-work pain. The questionnaire was administered as a pre-test and after five weeks. Post-test comparisons between groups indicated significant differences which were not present at pre-test. The viscoelastic group reported a significant peripheral shift in pain location from back to lower extremity; the viscoelastic group also showed significant changes in duration of post-work pain and frequency of pain during the workday. The clinical efficacy of viscoelastic shoe inserts for modifying weight bearing-induced back pain is supported. Further clinical research into the therapeutic and prophylactic value of shock-attenuating shoe inserts for healthy as well as patient populations is advocated.

Adult↗
PubMed1987

Bipolar prosthetic replacement for the management of unstable intertrochanteric hip fractures in the elderly.

To promote early full weight-bearing and rapid rehabilitation, 20 elderly patients (average age, 82.2 years) with unstable intertrochanteric hip fractures were treated with a bipolar head-neck replacement. Seventeen patients had the prosthesis inserted as primary fracture management, and three, for salvage of failed internal fixation. The patients were ambulating with unrestricted weight-bearing at an average of 5.5 days after the operation. The bipolar design may permit conversion to a total hip arthroplasty without removal of the femoral component, and may reduce the risk of acetabular cartilage damage. By using the greater trochanter as a landmark for precise placement of the femoral head, correct limb length was restored.

Aged↗
PubMed1987

Giant cell reaction of small bones.

A radiographically nonspecific lytic lesion in the middle phalanx of the index finger with microscopic evidence of a benign fibrous stroma with giant cells and osteoid was investigated in an 18-year-old man. Giant cell reaction is a rare, benign lesion of the small bones of the hands and feet. Trauma as the cause of a giant cell lesion poses an interesting question.

Adolescent↗
PubMed1986

Introduction of estrogen-responsiveness into mammalian cell lines.

We introduced estrogen responsiveness as a new characteristic into rat hepatoma, mouse Ltk- and human HeLatk-cells by transfecting the human estrogen receptor (ER) cDNA. To measure the estrogen response we used Xenopus vitellogenin gene A2 constructs linked to the bacterial CAT gene. Transient cotransfections of the ER cDNA and the vitellogenin gene-CAT constructs containing the estrogen responsive element (ERE) lead to a hormone dependent induction of CAT activity whereas cotransfected vitellogenin gene constructs lacking the ERE are not inducible. Stable transfections of ER cDNA into Ltk- cells give rise to cell clones that are estrogen responsive as shown by transfection of various vitellogenin gene-CAT constructs. These results prove that the transfected ER is biologically active and is sufficient to make a cell estrogen responsive.

Acetyltransferases↗
PubMed1986

Early prediction of mortality in patients with acute myocardial infarction: a prospective study of clinical and radionuclide risk factors.

To examine the prognostic value of early radionuclide imaging in patients with transmural acute myocardial infarction, 222 patients in Killip class I and II were studied prospectively within 24 hours of the onset of symptoms. The 30-day mortality rate for the entire group was 11% (25 of 222). Univariate analysis indicated that an initial radionuclide left ventricular ejection fraction (EF) of less than 0.30 was associated with the greatest relative risk (RR = 6.6), although the percent of abnormally contracting regions (RR = 3.9) and thallium-201 defect index (RR = 3.3) were also significant risk factors. Stepwise logistic regression indicated that addition of EF resulted in the greatest improvement over the best clinical model (Killip class and chest radiographic findings) for the prediction of 30-day mortality (chi 2 improvement = 12.8, p less than 0.0005). Using the optimal model for prediction of mortality (EF and Killip class), a high-risk group with a 30-day mortality rate of 39% (90-day mortality 47%) and a low-risk group with a 30-day mortality rate of 3% (90-day mortality 4%) was identified. In clinically stable patients with transmural acute myocardial infarction, early assessment of EF in conjunction with clinical evaluation, is a valuable method for early identification of high-risk subsets.

Analysis of Variance↗
PubMed1986

The chicken oestrogen receptor sequence: homology with v-erbA and the human oestrogen and glucocorticoid receptors.

A chicken oviduct cDNA clone containing the complete open reading frame of the oestrogen receptor (ER) has been isolated and sequenced. The mol. wt of the predicted 589-amino acid protein is approximately 66 kd which is very close to that of the human ER. Comparison of the human and chicken amino acid sequences shows that 80% of their amino acids are identical. There are three highly conserved regions; the second and third of which probably represent the DNA- and hormone-binding domains of the receptor. The putative DNA-binding domain is characterised by its high cysteine and basic amino acid content, and the hormone-binding domain by its overall hydrophobicity. These two domains of homology are also present in the human glucocorticoid receptor (GR) and the product of the avian erythroblastosis virus (AEV) gene, v-erbA, indicating that c-erbA, the cellular counterpart of v-erbA, belongs to a multigene family of transcriptional regulatory proteins which bind steroid-related ligands. The first highly conserved ER region is not present in the truncated v-erbA gene, but shares some homology with the N-terminal end of the GR. The function of the v-erbA gene product is discussed in relation to its homology with the ER and GR sequences.

Amino Acid Sequence↗
PubMed1986

Localisation of the oestradiol-binding and putative DNA-binding domains of the human oestrogen receptor.

Site-directed mutagenesis was used to prepare a series of human oestrogen receptor (hER) deletion mutants. The ability of these mutant receptors to bind oestradiol, either after being transiently expressed in HeLa cells or produced synthetically in vitro using T7 polymerase coupled with a rabbit reticulocyte lysate translation system, was analysed. The results indicate that a region which is highly conserved (94% amino acid identity) between the human and chicken ERs (region E) contains all of the sequence necessary to bind oestradiol with high affinity. When tight nuclear association of the oestradiol-receptor complex was investigated using the oestradiol-binding mutants of the same series, two regions of the hER sequence were found to be important. One of these regions is completely conserved (100% amino acid identity) between the human and chicken ERs (region C). This region is rich in cysteine and basic amino acids and contains motifs similar to those which have been proposed to be important for DNA binding in other eukaryotic transcriptional regulatory proteins. The other region (region D), which is comparatively poorly conserved (38% amino acid identity), is located between the putative DNA-binding domain (region C) and the oestradiol-binding domain (region E).

Animals↗
PubMed1986

Effects of chlordiazepoxide on cued radial maze performance in rats.

Effects of chlordiazepoxide (CDP) were examined on the performance of rats in an eight-arm radial maze with four cued and food-baited arms. Two conditions were used; random, with cue location varying over trials, and constant, with the same subset of arms consistently cued. In rats pre-trained to a 60-70% efficiency level (Rewarded entries/Total entries X 100), the effects of CDP (2.5, 5.0 and 10.0 mg/kg, IP) differed according to condition. Efficiency was substantially reduced in the random condition, and types of error were undifferentiated. In the constant cue condition the post-drug drop in efficiency was less marked, and errors were selectively those of re-entry into rewarded arms. In both conditions there was a high incidence of error clusters involving re-entries into both rewarded and non-rewarded arms in the random condition, and rewarded arms in the constant condition. The results suggested that CDP induced a general disruption of information processing rather than a specific impairment of working memory, together with some response perseveration which could occur in the presence or absence of discrimination failure.

Animals↗