PubMed Health⌕ Search

Biomedical subjects

A J Gray

Publications and source records attributed to A J Gray.

At least 19 recordsLinked to original sources
PubMed1995

The mitogenic effects of the B beta chain of fibrinogen are mediated through cell surface calreticulin.

We have previously shown that soluble partially degraded fibrin(ogen) remains in solution after fibrin clot formation and is a potent fibroblast mitogen (Gray, A.J., Bishop, J.E., Reeves J.T., Mecham, R.P., and Laurent, G.J. (1995) Am. J. Cell Mol. Biol. 12, 684-690). Mitogenic sites within the fibrin(ogen) molecule are located on the A alpha and B beta chains of the protein (Gray, A.J., Bishop, J. E., Reeves, J.T., and Laurent, G.J. (1993) J. Cell Sci. 104, 409-413). However, receptor pathways through which mitogenic effects are mediated are unknown. The present study sought to determine the nature of fibrin(ogen) receptors expressed on human fibroblasts which interact with the fibrinogen B beta chain. Receptor complexes were isolated from 125I-surface-labeled fibroblasts and purified on a fibrinogen B beta chain affinity column. Subsequent high performance liquid chromatography and SDS-polyacrylamide gel electrophoresis analysis indicated fibrinogen B beta chain bound specifically to a 60-kDa surface protein. Sequence analysis of the amino terminus of this protein indicated 100% homology to human calreticulin. Immunoprecipitation experiments employing a polyclonal anti-calreticulin antibody provided further evidence that the 60-kDa protein isolated in this study was calreticulin. Further, polyclonal antibodies to human calreticulin significantly inhibited the mitogenic activity of fibrinogen B beta chain on human fibroblasts. The present study has shown that cell surface calreticulin binds to the B beta chain of fibrinogen mediating its mitogenic activity.

Amino Acid Sequence↗
PubMed1995

Role of thrombin in pulmonary fibrosis.

Pulmonary fibrosis commonly develops in systemic sclerosis. We assessed the role of thrombin in promoting fibroblast proliferation in the lungs in this disorder. Bronchoalveolar lavage fluid (BALF) thrombin concentrations were higher in ten patients with systemic sclerosis than in 12 healthy controls (14.6 vs 3.6 nmol/L, p < 0.02), but values in patients with cryptogenic fibrosing alveolitis (n = 10) or sarcoidosis (n = 10) were not increased. BALF from all patients induced fibroblast proliferation. This proliferation was attenuated by thrombin inhibitors for BALF from systemic sclerosis patients only. We suggest thrombin contributes to lung fibroblast proliferation in this disorder.

Alveolitis, Extrinsic Allergic↗
PubMed1995

Doctors' legal position in treating temporarily incompetent patients.

Doctors in accident and emergency departments are sometimes presented with patients with potentially life threatening conditions who refuse to consent to treatment. The doctors then face a dilemma: to withhold necessary treatment or to act against a patient's express wishes. Two such cases are presented, and we asked a lawyer, two medical ethicists, a psychiatrist, and an accident and emergency physician to comment on the implications.

Adult↗
PubMed1995

Partially degraded fibrin(ogen) stimulates fibroblast proliferation in vitro.

The conversion by thrombin of soluble plasma fibrinogen to an insoluble fibrin matrix is central to hemostasis and subsequent wound healing. Fibroblasts adhere to and rapidly grow into fibrin clots, resulting in collagen deposition and, ultimately, scar formation. Although a number of soluble mediators have been implicated in this process, a role for fibrin(ogen) itself has not been described. The present study further investigated the nature of mitogenic activity remaining in solution after in vitro fibrin clot formation. Liquid expressed from a fibrin clot (clot supernatant) elicited a mitogenic response of up to 83 +/- 4.7% above media control. Upon addition of a polyclonal fibrinogen antibody, this activity was reduced by 50%. The remaining activity was attributed to the presence of thrombin and was neutralized by the addition of a specific thrombin inhibitor. Fibrinogen cleavage products were separated by molecular sieve chromatography and the mitogenic potential of each fraction assessed. A peak of activity was observed in fractions containing proteins with apparent molecular weights of 200 to 300 kD. Enhanced chemiluminescence Western blotting of these fractions established the presence of several fibrin(ogen)-derived protein bands. It is therefore proposed that thrombin cleavage of fibrinogen, in addition to producing fibrin, generates high-molecular-weight soluble cleavage products that may play an important role during normal wound healing and in the pathogenesis of disease states associated with vascular leakage and fibrosis.

Cell Division↗
PubMed1994

Intracapsular fractures of the femoral neck in young patients.

The details of the aetiology, treatment and outcome of acute intracapsular fractures for 58 fractures in 57 patients aged less than 60 years, were prospectively studied. The majority of the injuries were sustained by low energy trauma. Eighty-four per cent united uneventfully. There was a non-union rate of 7 per cent, and avascular necrosis rate of 10 per cent. Better results were obtained from closed than open reduction. The results do not support the commonly held view that this injury carries a poor prognosis in young patients.

Accidental Falls↗
PubMed1994

A 5-10 year follow-up of the Sheehan total knee endoprosthesis in Tayside.

The Sheehan total knee endoprosthesis has been widely used since 1971. It takes the form of a semi-constrained hinge with intramedullary stems cemented into the femur and tibia for fixation. In Tayside the prosthesis has been in use since 1980. The clinical impression was that the prosthesis was not performing well and formal assessment of surviving prostheses was therefore carried out using the Hospital for Special Surgery (HSS) scoring system. Thirty-seven patients were available for follow-up, 15.6% of whom had good results while 40% had poor results according to this assessment. At review, 31% of patients had undergone revision surgery or were awaiting such surgery. This compares poorly with reported results of surface joint replacements. In the light of these results the authors feel that the Sheehan knee replacement is now obsolete.

Aged↗
PubMed1992

Treatment and planning decisions in non-small cell carcinoma of the lung: an Australasian patterns of practice study.

Fourteen practising radiation oncologists were surveyed to assess their treatment and planning habits utilizing six sample cases of non-small cell carcinoma of the lung. Respondents were first given a general questionnaire, designed to evaluate their theoretical treatment and planning recommendations based on various tumour and patient related variables. Respondents then undertook a practical planning exercise utilizing planning CT and simulator radiographs for each of the six sample cases. Each case was accompanied by a brief history and report outlining specific tumour stage and non-stage related variables. The practical planning exercise was repeated on the second day of the survey utilizing different non-stage related variables but identical radiology and stage-related information. This design enabled firstly, a comparison of clinicians' intended policy and planning methods with actual policy and planning decisions, and secondly, an assessment of intra-clinician variability in decision making and planning practice. Good agreement was evident among clinicians with respect to general, non-case specific treatment policies; however, very significant variation occurred at an inter- and intra-clinician level and involved the entire treatment and planning process for individual cases. Despite identical treatment intent across identical radiological case pairings, clinicians chose widely differing margins and target volumes in their planning exercise. Treatment intent appeared to be influenced more by non-stage related variables rather than stage related information and radiological appearances per se. We have shown that experienced radiation oncologists do not adhere to stated case selection criteria and show inconsistencies in their treatment planning for non-small cell carcinoma of the lung.

Australia↗
PubMed1992

Waiting times and patient satisfaction in the accident and emergency department.

A survey of the waiting times and patients' opinions of these times was undertaken in a busy district general hospital A&E department. The various components of the overall waiting time are analysed and specific points of the patients' attendance, where waiting times were prolonged, are identified. Standards are derived which is hoped may result in 75% of patients being satisfied with the duration of their wait. The current levels of achievement are compared with these standards. Suggested and actual improvements to the department to improve our performance are described.

Emergency Service, Hospital↗
PubMed1992

Can ambulance personnel intubate?

To assess the performance of intubation skills by advanced trained ambulance personnel, a prospective study was carried out of the intubation of cardiac arrest victims by ambulance personnel in the field. Twenty-eight ambulance personnel attempted the intubation of 87 patients over 2 years. Eighty-five patients were initially successfully intubated, one endotracheal tube became displaced and cuff leakage occurred on three occasions. This was treated appropriately in each instance. Ambulance personnel can perform the skills of intubation successfully in out-of-hospital cardiac arrest victims.

Ambulances↗
PubMed1992

Endothelin-1 and endothelin-3 induce chemotaxis and replication of pulmonary artery fibroblasts.

The remodeling of pulmonary vessels that occurs in association with pulmonary hypertension involves, in part, thickening of the adventitia. The stimulus for this process is not understood. One explanation is that endothelial cells secrete a growth factor that expands the local population of fibroblasts by acting as a chemoattractant and mitogen. Endothelins are a family of potent newly discovered vasoactive peptides. One of these compounds, endothelin-1 (ET-1), is secreted by endothelial cells and is known to constrict pulmonary vessels. Another, endothelin-3 (ET-3), is not secreted by endothelial cells and is less potent as a pulmonary vasoconstrictor. We hypothesized that the endothelins may have the capacity both to constrict these vessels and to initiate fibroblast chemotaxis and replication. Here we investigated the effects of both ET-1 and ET-3 on the chemotaxis and replication of fibroblasts derived from pulmonary vessels. Cells were isolated from rat pulmonary arteries, cultured in medium and 10% newborn calf serum, and used between passages 2 and 5. Chemotaxis was assessed using a modified Boyden chamber with a polycarbonate filter (pore size, 8 microns) separating cells in the upper chambers from endothelin in the lower chambers. Replication was assessed both by direct cell counts and by a colorimetric assay based on uptake and subsequent release of methylene blue. Both ET-1 and ET-3 induced chemotaxis of pulmonary artery fibroblasts and did so in a dose-dependent fashion. The maxima for both peptides occurred at a concentration of about 10(-7) M, when chemotaxis was greatest for ET-1 (22 +/- 1.4 versus 14 +/- 1.8 cells/grid [mean +/- SEM], (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Eosinophils adhere to and stimulate replication of lung fibroblasts 'in vitro'.

Eosinophils have been implicated in several disorders associated with the development of fibrosis. This led us to investigate the interactions between eosinophils and fibroblasts in vitro. Adhesion between purified guinea pig peritoneal eosinophils and monolayers of human fetal lung fibroblasts was assessed using the rose bengal dye staining assay. Fibroblast replication was assessed using a colorimetric assay based upon the uptake and subsequent release of methylene blue. Addition of phorbol myristate acetate induced a rapid, time-dependent increase in eosinophil adhesion (127% and 328% over basal adhesion after 10 and 30 min, respectively). Phorbol myristate acetate-induced adhesion was inhibited by the peptides RGDS and GRGDS (48% and 42%, respectively using 1 mM peptide) and by nordihydroguaiaretic acid, an inhibitor of the lipoxygenase pathway of arachidonic acid metabolism (46% inhibition at 15 microM). In addition, 24 h culture of fibroblast monolayers with interleukin 1 alpha (IL-1 alpha) or tumour necrosis factor alpha (TNF alpha) resulted in enhanced adhesion (10 U/ml IL-1 alpha stimulated adhesion by 55% of control, 500 U/ml TNF alpha by 75% of control). Conditioned media from cultured eosinophils stimulated fibroblast replication in a time-dependent fashion with maximal stimulation at 3 h. In contrast, media from guinea pig peritoneal macrophages in culture did not show such an effect. This study indicates that eosinophils are capable of both adhering to and releasing mitogens for fibroblasts in vitro. These observations suggest that eosinophils have the capacity to play a role in the development of fibrosis in disorders where they have been shown to be present.

Amino Acid Sequence↗
PubMed1990

Results of treatment of cancer of the cervix in Wellington 1980-4.

A review was undertaken of all 115 women with invasive carcinoma of the cervix referred for treatment to the Wellington regional centre during the period 1980-4. In comparison with the previous five year period, there were 31 (37%) more patients, and a higher proportion of patients had stage I and II disease. The incidence of disease was significantly greater in Maori compared with nonMaori. Treatment was by various combinations of surgery and radiation according to agreed protocols. The actuarial survival at five years was 73% for the whole group, 89% for 64 stage I patients, 65% for 28 stage II patients and 45% for 19 stage III patients. The actuarial risk of a major treatment complication within the first five years was 8.8%. These results confirm that regional centres in New Zealand employing a multidisciplinary approach to patient assessment and treatment can achieve high cure rates with an acceptable incidence of treatment complications. However, prevention of the disease by effective cervical screening programmes should remain an objective of health services in New Zealand.

Adult↗
PubMed1990

The comparative disposition of [14C]-fotemustine in non-tumourous and tumourous mice.

The distribution and excretion of radioactivity from [14C]-fotemustine was examined in mice with melanomas at different stages of development to determine whether the disease state substantially alters the disposition of the drug and its metabolites. Normal BDF1 mice and mice that had been subcutaneously grafted with B16 melanoma either 1, 3, 7, 14 or 21 days previously were used. The animals were killed at either 5 min, or at 3, 24 or 96 h after receiving an intravenous dose of [14C]-fotemustine (20 mg/kg) and were examined either by whole-body autoradiography or by liquid scintillation counting of excreta and tissues of interest. The majority of the [14C]-fotemustine dose was excreted in the urine, with similar amounts being measured in both non-tumourous animals (61.6% +/- 13.1%) and tumourous mice grafted 14 days previously (67.2% +/- 5.7%). Small amounts of radioactivity, again similar in both non-tumourous and tumourous mice, were recovered in the faeces (5.4% +/- 5.6% and 3.6% +/- 1.8%, respectively) and as carbon dioxide (7% +/- 3.5% and 6.4% +/- 1%, respectively), with minimal amounts being expired as chloroethanol (less than 1%). When mice were examined 5 min after dosing, there was extensive tissue distribution accounting for 75% +/- 10% of the dose. The highest concentrations determined by both whole-body autoradiography and liquid scintillation counting were measured in the excretory organs, with 33 and 28 micrograms Eq/g being found in the liver and kidney, respectively. High levels were also seen in the lung and plasma (19.8 and 19.5 micrograms Eq/g, respectively). Analysis of variance indicated that groups of tissues, such as the excretory organs, blood and plasma or the pigmented tissues, showed distinct but inconsistent patterns. Only tumours at 14 and 21 days of development were suitable for examination, and these showed levels of 12.1 micrograms Eq/g; however, the tumour-to-plasma ratio increased from between approx. 0.5 and 0.6 at 5 min to approx. 2 at 96 h after dosing, suggesting retention within the melanoma, whereas the ratio for the femur remained at approx. 1. Whole-body autoradiography showed that the distribution in the tumour was not uniform, but rather was concentrated in the peripheral area (presumably viable cells) as opposed to the central necrotic region. Thus, the high and sustained concentration of radioactivity found in the active cells of the melanoma may provide an explanation for the high efficacy of the drug.

Animals↗
PubMed1990

Accelerated fractionation radiotherapy for advanced head and neck cancer.

Between 1981 and 1986, 89 patients with advanced head and neck squamous cancer were treated with a continuous accelerated fractionation radiotherapy (AFRT) regimen. Three fractions of 1.80 Gy, 4 h apart, were given on three treatment days per week (Monday, Wednesday, Friday), and the tumour dose was taken to 59.40 Gy in 33 fractions in 24-25 days. Acute mucosal reactions were generally quite severe, but a split was avoided by providing the patient with intensive support, often as an in-patient, until the reactions settled. Late radiation effects have been comparable to those obtained with conventional fractionation. The probability of local-regional control was 47% at 3 years for 69 previously untreated patients, whereas it was only 12% at one year for 20 patients treated for recurrence after radical surgery. Fifty-eight previously untreated patients with tumours arising in the upper aero-digestive tract were analysed in greater detail. The probability of local-regional control at 3 years was 78% for 17 Stage III patients and 15% for 31 Stage IV patients. This schedule of continuous AFRT is feasible and merits further investigation.

Carcinoma, Squamous Cell↗
PubMed1990

Disposition, pharmacokinetics, and metabolism of 14C-fotemustine in cancer patients.

The pharmacokinetics and metabolism of intravenously infused 14C-fotemustine (about 100 mg/m2) were examined in 2 cancer patients. Plasma levels of radioactivity increased to a maximum of 4.1 and 5.5 micrograms equivalents per g when the infusion stopped then declined triexponentially with mean half-lives of about 1/2, 10 and 80 h for the initial, mid and terminal phases, respectively. Plasma levels of intact drug were lower, with maximum levels of 1.1 and 2.8 micrograms/ml, and declined monophasically with a half-life of about 24 min. Plasma clearance was high (1426 and 764 ml/min) with the volume of distribution based on areas of 47.7 and 26.4 l. Most of the radioactivity was eliminated in urine (50.1 and 61.3%) over 7 days with smaller amounts in the feces (6.8 and 0.3%) and only minimal quantities (under 0.1%) as expired carbon dioxide. Metabolites of fotemustine were identified as chloroethanol and N-nitroso-1-imidazolone-ethyl-diethylphosphonate in plasma and as 1-hydantoin-ethyl-diethyl-phosphonate and acetic acid in urine.

Aged↗
PubMed1990

Growth factors for human fibroblasts in the solute remaining after clot formation.

Fibroblasts adhere to, and readily grow into, fibrin clots that form as a result of the cleavage of fibrinogen by thrombin. Subsequent fibroblast replication is believed to be stimulated by mitogens released by entrapped platelets, such as platelet-derived growth factor. We suggest that the supernatant remaining after the fibrinogen-thrombin reaction could stimulate fibroblast replication, even in the absence of other blood components. To examine this hypothesis we expressed liquid from a fibrin clot and measured its mitogenic activity on human lung fibroblasts, in serum-free conditions, using a colorimetric assay based on uptake and subsequent release of Methylene Blue. The clot supernatant caused a mitogenic response of 51 +/- 6% above control and was equivalent to about half that elicited by medium containing 10% newborn calf serum. On their own, both thrombin and fibrinopeptides A and B (small molecular weight cleavage products released from fibrinogen) showed some mitogenic activity, but there was also activity in higher molecular weight cleavage products, suggesting the presence of uncharacterized mitogens. It is proposed that these agents may play important roles in wound healing and diseases associated with vascular leakage and fibrosis, by stimulating fibroblast replication.

Blood Coagulation↗