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Biomedical subjects

J Nixon

Publications and source records attributed to J Nixon.

At least 19 recordsLinked to original sources
PubMed1992

Microculture-based chemosensitivity testing: a feasibility study comparing freshly explanted human melanoma cells with human melanoma cell lines.

BACKGROUND: The culture of cancer cells has many applications in chemosensitivity testing and new drug development. PURPOSE: Our goal was to adapt simple semiautomated microculture methods for testing the chemosensitivity of melanoma cells freshly recovered from patients' tumors. METHODS: Cells were cultured on a substrate of agarose and exposed continuously to cytotoxic drugs, the effects of which were measured by determining the uptake of [3H]thymidine 4-7 days later. RESULTS: Immunocytochemical staining of cells cultured with 5-bromo-2'-deoxyuridine demonstrated that tumor cells were responsible for the measured thymidine incorporation. The effects of cytotoxic drugs were calculated as logarithmic 50% inhibitory concentrations and expressed as divergences from the mean in a log-mean graph. The inhibitory effects of amsacrine, etoposide, doxorubicin, cisplatin, mitomycin C, and fluorouracil were tested. Tumors differed widely in their sensitivity to these drugs, although sensitivity to the three topoisomerase-II-directed agents was highly correlated. Cells from two non-neoplastic hematopoietic progenitor cell lines (FT and 32D) showed chemosensitivity patterns distinct from those in the melanoma cells, indicating tissue selectivity. Two established melanoma cell lines, MM-96 and FME, were tested under the same conditions and showed sensitivity typical of at least some fresh specimens. CONCLUSIONS: These results support the validity of melanoma cell lines as models of freshly resected melanoma cells. If successfully applied to other tumor types, such semiautomated approaches could find wide application in routine hospital laboratories for the chemosensitivity testing of patients' tumor cells.

Animals↗
PubMed1991

Attitude, anxiety, and social readjustment toward learning disabilities by student teachers.

84 student teachers from undergraduate classes at a western university in Kansas completed a 9-question checklist of learning disabilities before interacting with a behavioral disordered/learning disabilities teacher, a paraprofessional, and a high school learning-disabled student. After the dialog, the student teachers completed a Social Readjustment Rating Scale, Breskin Rigidity Test, the Self-evaluation Questionnaire: State and Trait Anxiety, and the same 9-question checklist with one additional question ("Now that you have seen a learning-disabled student has it affected your opinion of learning disabilities?"). The dialog affected 63% of the students' opinions while 31% stated the presentation did not affect their opinion (6% were missing or not completed). Persons who experienced more life-changes and problems tended to rate or view learning disabilities more negatively. The more trait anxiety experienced by the students, the lower they rated learning disabilities after the presentation.

Adolescent↗
PubMed1990

Platelet-derived growth factor and its receptor in blood cell differentiation and neoplasia.

Platelet-derived growth factor (PDGF) is a family of dimeric protein molecules synthesized by differentiated, non-dividing and proliferating blood cells. Experimental findings indicate that PDGF is involved in development and/or maintenance of physiological functions of certain normal blood cells. Also, PDGF synthesis correlates with certain blood cell proliferative diseases caused either spontaneously or associated with viral infection. There is increasing evidence that the diverse effects of PDGF in both normal and abnormal physiological functions of blood cells may be regulated at the level of its receptor. New experimental findings are discussed relating to PDGF receptors in normal leukemic, and virally-infected human cells of myeloid and lymphocytic lineages. At specific developmental stages this regulation may take the form of PDGF and its receptor being expressed or co-expressed; the unmodified or modified form of receptor that specifically interacts with PDGF; the cellular site at which the PDGF-receptor interacts with its ligand; and co-expression of the PDGF-receptor with other receptors associated with specific cell lineage or functions. Elucidation of events involved in synthesis, processing, and interactions of PDGF isoforms and their respective receptors will enable us to develop pharmacological means that may either interfere with, or enhance these desired blood cell functions. This review focuses on PDGF and its receptor in human blood cell differentiation and neoplasia.

Blood Cells↗
PubMed1990

The role of dacryocystography in the management of patients with epiphora.

A retrospective study has been carried out on 114 patients who have undergone dacryocystography (DCG) for epiphora, to assess the role of DCG in their management. It was found that 16/66 (24%) patients who were offered surgery after DCG refused it or were assessed as unfit for surgery, demonstrating the need for careful counselling and assessment of patients prior to investigation. The presence of lacrimal system obstruction on DCG was an important factor in determining whether a patient underwent lacrimal surgery. However, the actual level of the obstruction influenced neither the likelihood of a patient undergoing lacrimal surgery nor the form of lacrimal surgery undertaken. This suggests that, unless the surgical approach will be modified in the light of the anatomical information furnished by DCG, DCG is not necessary. Lacrimal scintigraphy would provide sufficient information for the practical management of epiphora. Syringing of the lacrimal system correlates poorly with DCG in detecting obstruction.

Dacryocystorhinostomy↗
PubMed1988

Disease relapse in patients with stage I nonseminomatous germ cell tumor of the testis on active surveillance.

Thirty-six patients with apparent stage I nonseminomatous germ cell tumor (NSGCT) of the testis were treated by inguinal orchidectomy and intensive follow-up only. Assessment included measurement of serum alpha fetoprotein (alpha FP) and beta human chorionic gonadotropin (beta HCG) (tumor markers) and chest x-ray monthly for 1 year, then twice monthly for 1 year, with computed tomographic (CT) scans of abdomen and chest repeated three times monthly for the first year and six times monthly for the second year. Median follow-up was 36 months (range, 14 to 92 months). Relapse occurred in 12 patients (33.3%) at a median of 7 months (range, 2 to 28 months). Elevated markers were of limited importance in relapse detection, confirming the need for close clinical and radiological follow-up. Of nine histological factors examined in the primary tumor only the presence of lymphatic invasion was associated with a significantly higher relapse rate. All patients were treated at relapse with cisplatin-based chemotherapy. Four underwent surgery in addition, two before and two after chemotherapy. Eleven were rendered disease-free, but four had a second relapse. One patient has died, one is alive with disease, and ten are disease-free. Chemotherapy failed to cure six patients who had relapsed but bulk of disease was not a factor. Despite the good overall result reported here, optimal postorchidectomy management of apparent stage I disease remains to be defined.

Adolescent↗
PubMed1987

Bicycle accidents in childhood.

The results of a 10 year study of bicycle fatalities and an eight year study of serious non-fatalities are reported for urban Brisbane (population 1,000,000). There were 845 serious non-fatal bicycle accidents and 46 fatalities during the study. Boys were involved in 86% of accidents. Boys have an accident rate of 134.21 per 100,000 population at risk and a fatality rate of 5.06 per 100,000 at risk. Serious bicycle accidents have increased by 50% in this decade; but considering fatal cases alone, no secular trend was evident over the 10 year period of the study. This suggests that an increase in the overall rate of bicycle accidents has been in part compensated by less serious injuries. In 70% of fatalities children had head injuries, and 87% of fatalities followed a collision between a cyclist and a motor vehicle or a train. Bicycle accidents on the roads most commonly occur to boys aged between 12 and 14 years on a straight road at "mid-block" between 3 and 5 pm in clear weather conditions and in daylight. It is concluded that injuries and fatalities after bicycle accidents can be reduced by protecting children's heads, separating child cyclists from other road traffic, or educating and training both cyclists and other road users in safe behaviour. The compulsory use of helmets and the restriction of access to the roads by child cyclists to reduce injuries are, however, still controversial in many areas.

Accidents, Traffic↗
PubMed1987

The management of blunt splenic trauma.

Seventy cases of blunt splenic trauma were retrospectively reviewed for the period 1979-1984. There were 57 adults and 13 children. Motor vehicle accidents were implicated in 62%. Forty-five splenectomies and eight splenorrhaphies were performed. The patients fell into two groups. Group A, numbering 48 patients, were those operated upon within 24 hours of injury. The mortality rate was 16%, and no deaths were attributable to splenic injury. Indications for surgery were hemodynamic instability in 46% and positive peritoneal lavage in 40%. Group B included 22 patients, 17 of whom were managed nonoperatively with no deaths. Five patients eventually went to laparotomy. Fifty per cent of all patients had associated intra-abdominal injury but only 17% needed repair; 31% of patients were initially managed conservatively with a 77% success rate and no mortality. It is concluded that conservative management is safe in stable patients with blunt splenic trauma.

Accidents, Traffic↗
PubMed1986

Fifteen years of child drowning--a 1967-1981 analysis of all fatal cases from the Brisbane Drowning Study and an 11 year study of consecutive near-drowning cases.

A total population study of childhood fresh water drowning accidents (fatalities) for the 15 year period, 1967-1981, is reported. These data are from the ongoing Brisbane Drowning Study which has now also analysed 255 fresh water child immersions (both fatalities and near-fatalities) over the eleven year period, 1978-1981, and as such forms a consecutive unselected series for over one decade. The annual fatality (drowning) rate is 3.53 per 100,000. Details of immersion accidents by site, sex and by outcome (survivors versus fatalities) are presented. An analysis of secular trends revealed that one epidemic peak of child drownings in swimming pools and domestic baths (noted in the mid 1970s in Australia and other countries) is now passed. Evidence is presented to suggest that a vigorous education, and public awareness campaign can reduce the incidence of serious child immersion accidents by one-third. Such a campaign may have influence on all types of childhood household drownings (pools, baths, garden ponds), irrespective of site. Survival rates for unsupervised children who lose consciousness in fresh water are site-dependent, only 21% of such potential victims surviving after losing consciousness in rivers and creeks, compared with the survival rate of 65% for those in potential drowning incidents in their own backyard. Violent death continues to account for more than half of all deaths in childhood up to the age of 14 years [Gratz, 1979; Mayer, Walker and Johnson et al., 1981].(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Fatal and nonfatal accidents on the railways--a study of injuries to individuals, with particular reference to children and to nonfatal trauma.

This paper reports a five-year total population study of fatal railroad accidents involving individuals (that is, not including train crashes or derailments); and a consecutive unselected series of nonfatal isolated injuries in Queensland, Australia. There were 84 fatalities and 211 cases of significant nonfatal traumata. Fatal railway accidents involving children under 15 years of age are now more common in Australia than childhood poisonings and electrocutions. Two syndromes occur--(a) toddlers living near the tracks who simply wander onto the line; and (b) young teenage boys who are run down on level crossings, either as pedestrians or cyclists. Adult fatalities include (a) occupational deaths among railway workers (20%), (b) car-train collisions at level crossings (19%), (c) drunk pedestrians who walk into trains (17%), suicides (12%), and old folk who walk into trains (12%). Of 211 nonfatal cases studied, falls in and from both moving and stationary trains were the most common type of accident. Sudden jolting of the train (probably unpreventable) contributed to 26% of all falls. Twenty-two percent of nonfatal accidents resulted from a person being struck by a train. All persons who survived being struck by a train received serious injuries and required hospital admission. Fatalities involving adults include a high proportion of suicides. Some accidents, such as fingers being caught in windows and doors, can and are being overcome through improved design.

Accidents↗
PubMed1979

Orthopaedic complications of renal transplantation.

One hundred and eighty-one patients who underwent renal transplantation between 1973 and 1979 have been reviewed. Thirty of these developed one or more orthopaedic complications. The commonest and most serious was avascular necrosis of bone and the treatment of 14 patients with this condition is described. Transplant recipients who developed this complication received twice the total dose of steroids in the six months after transplantation than a control group with no avascular necrosis. The management and pathology of patients with avascular necrosis is discussed.

Adolescent↗
PubMed1977

Are swimming pools becoming more dangerous?

The rate of childhood drowning and near-drowning accidents in home swimming pools has doubled over the last five years. A study has been undertaken to determine whether this is due simply to an absolute increase in the number of home swimming pools, or whether pools themselves are becoming intrinsically more dangerous, or both. Direct measurement of pool-house ratios has been undertaken by means of aerial photography. Supportive data have been obtained from municipal records. Pool-home ratios for the cities of Canberra and Brisbane are compared (estimated 1: 10.7, and 1:13.3 respectively). It is suggested that swimming pools are not becoming intrinsically more dangerous to children; the data suggest that effective pool legislation will prevent childhood drownings in spite of increasing trends in home pool ownership.

Accidents, Home↗
PubMed1977

Further developments of the 'present state examination' and CATEGO system.

Some further developments of the PSE and CATEGO system are reported. The shorter ninth revision of the PSE, together with its glossary of definitions of symptoms, has proved useful in skilled hands and certain sources of error in the eighth edition have been reduced. The Syndrome Check List and Aetiology Schedule have proved useful in decreasing the number of coding errors.

Adult↗
PubMed1977

Prevention of childhood drowning accidents.

The data from the Brisban Drowning Study have been analysed in this article to provide guidelines for preventive strategies. The separate causal links comprising the drowning chain have been identified, and quantitative scores have been assigned to the three identifiable groups of causative factors--environmental, parent-related and victim-related. The identifiable causes of child drowning are absence of a safety barrier or fence around the water hazard, non-supervision of a child, a parental "vulnerable period", an inadequate safety barrier, and tempting objects in or on the water. Effective environmental control can be achieved only through legislation. The complementary role of a public educational thrust in discussed. Increasing the tempo of "drownproofing* and of teaching children to swim will help, but the expected reduction in deaths and near-deaths from this strategy alone cannot yet be assessed. Compulsory first aid training for pool owners is required. Costs of implementing a total drowning preventive programme are presented.

Age Factors↗