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Biomedical subjects

J A Ross

Publications and source records attributed to J A Ross.

At least 19 recordsLinked to original sources
PubMed1992

Insertion of SMRV-H viral DNA at the c-myc gene locus of a BL cell line and presence in established cell lines.

Mutation of the c-myc gene locus has occurred during in vitro culture of the Burkitt lymphoma cell line Namalwa. Gene cloning and sequencing of this c-myc gene locus has revealed the insertion of incomplete copies of the Squirrel Monkey Retrovirus-Human (SMRV-H) proviral genome. Insertions of the SMRV-H genome were seen in all Namalwa cell lines tested, with multiple insertions being seen in some sublines. Viral particles with the morphology of type-D retrovirus, budding from these cells, were seen by transmission EM. New insertions of the genome were produced spontaneously in these cells. The origins of the type-D retrovirus and its implications for workers in the field are discussed.

Base Sequence↗
PubMed1992

Weight loss in a murine cachexia model is not associated with the cytokines tumour necrosis factor-alpha or interleukin-6.

Daily administration of an escalating dose of tumour necrosis factor-alpha (TNF-alpha) to female NMRI mice caused a progressive loss of body weight representing 12% of the original weight over a 6-day period. Weight loss was associated with a decreased food intake and pair-fed controls exhibited a weight loss of similar magnitude to that caused by TNF-alpha. However, weight loss in animals bearing a murine adenocarcinoma (MAC16) occurred without a change in energy intake and thus differed from that produced by TNF-alpha. Anti-TNF-alpha monoclonal antibodies at levels capable of protecting mice against lethal endotoxaemia were ineffective in reversing weight loss in animals bearing the MAC16 tumour and had no effect on the increase in tumour volume. Circulating levels of interleukin-6 were not elevated in animals bearing the MAC16 tumour and with a weight loss between 1.8 and 5.4 g. These results suggest that these cytokines are not involved in the cachexia produced by this murine tumour.

Adenocarcinoma↗
PubMed1992

DNA adducts and induction of sister chromatid exchanges in the rat following benzo[b]fluoranthene administration.

Benzo[b]fluoranthene (B[b]F) was administered (100 mg/kg by i.p. injection) to male Sprague--Dawley rats. Lungs, livers and peripheral blood lymphocytes (PBLs) were harvested 1, 3, 5, 7, 14, 28 and 56 days after treatment. Several DNA adducts were observed in each tissue, with maximal levels occurring at approximately 7 days after treatment. Lung DNA exhibited consistently higher adduct levels than liver or PBL DNA. At 56 days after B[b]F administration, the adducts in liver and PBL DNA were present at < 10 amol/microgram DNA, while in lung there were 100 amoles/microgram DNA. No significant differences were observed between tissues in the types of adducts produced. Co-chromatography with synthetic standards showed that only a minor adduct produced in vivo is derived from trans-9,10-dihydro-9,10-dihydroxybenzo[b]fluoranthene-11,12-oxide. Sister chromatid exchanges (SCEs) from whole blood cultures were significantly increased relative to concurrent controls between 1 and 14 days after B[b]F administration, with maximum levels at 14 days. By 28 days after treatment, SCEs had essentially returned to control levels. SCE induction did not correlate with the amount of B[b]F--DNA adducts remaining in the PBLs at harvest time.

Animals↗
PubMed1992

Occupational accidents presenting to the accident and emergency department.

A prospective survey of patients attending the major Accident and Emergency Department in Aberdeen was undertaken. This department serves a population of 500,000 and sees some 50% of all accidents in the region. All work-related injuries were identified and information relating to the circumstances of the accident, injury sustained, and treatment required was sought. Work-related injuries accounted for 16.5% of new patients attending the department. The commonest injury type was a laceration to a finger. Three hundred and eighty diagnostic X-rays were undertaken and a total of 910 treatments were required over a 27-day period. On an annual basis, it is estimated that some 5100 radiographs and 12,300 medical treatments would be required for work-related accidents. It is estimated that 30% of injuries to the hands and feet would have been prevented by the wearing of appropriate personal protective equipment. The majority of workplace accidents were correctly referred to A&E and any efforts to reduce this workload must concentrate on preventive measures in the workplace. This paper suggests that documenting work-related accidents and determining targets for preventive action would reduce the number of attendances at A&E units with a potential significant saving for industry and the National Health Service.

Accidents, Occupational↗
PubMed1992

Psychophysics of reading. Clinical predictors of low-vision reading speed.

Clinicians need to estimate how well their low-vision patients will perform everyday visual tasks such as reading or driving. Typically, it is not practical to measure task performance directly or to administer a lengthy series of special tests. Recent laboratory research has suggested that some routine clinical data may be useful in predicting reading performance. The purpose of the present study was to determine whether a promising set of simple measures--Snellen acuity, status of the central fields and ocular media, diagnosis, and age--could be used in a clinical setting to predict reading speed. One hundred and forty one patients who entered the low-vision clinic of the Minneapolis Society for the Blind received thorough eye examinations and a test of reading speed. Snellen acuity accounted for only 10% of the variance in reading speeds overall, but played a more important role for subjects with central loss. Age was a better predictor than acuity. A diagnosis of age-related maculopathy predicted slower reading speed than other causes of central-field loss, but the difference was attributed to age. Media status (clear or cloudy) had no predictive value. Our set of clinical predictors accounted for only about 30% of the variance in low-vision reading speeds. While data from more detailed visual testing might improve prediction, nonvisual factors such as age probably also contribute to the variance. Rather than relying on predictions from visual testing, clinical assessment of low-vision reading may be accomplished most easily with a suitably designed reading test.

Adolescent↗
PubMed1991

Psychophysics of reading--X. Effects of age-related changes in vision.

This study examined the influence of age-related changes in vision on reading performance. Maximum reading speed was measured in groups of young (n = 16, mean age 21.6 years) and old (n = 14, mean age 68.3 years) subjects, all with acuities of 20/32 or better. A psychophysical procedure was used for measuring reading speed that has proven reliable and sensitive to visual factors in previous research. Data were collected for character sizes ranging from .15 degrees to 12 degrees. Research revealed that old subjects who were free of eye disease read as fast as the young subjects for character sizes ranging from .3 degrees to 1.0 degrees. This is the range in which reading speed is maximum for young subjects. Research also revealed that old subjects showed a deficit when reading text composed of very small or very large characters. Their speeds dropped to about 70% of the young adult speeds. These deficits may be due to age-related losses in visual contrast sensitivity.

Adult↗
PubMed1991

Accidents in the workplace.

A prospective survey of patients attending the central Accident and Emergency Department and Eye Casualty Department in Aberdeen was made to determine the contribution of accidents at work to the workload of the departments and to estimate risks of injury in different industrial sectors. Work-related injuries accounted for 16.5 per cent of new patients attending the general accident department and 21.7 per cent of those attending eye casualty. Analysis by industrial sector led to estimates that almost one in 10 workers employed in manufacturing industries and in agriculture/forestry/fishing will attend casualty in the course of a year for a work-related injury. The relatively low-risk service sector, because of the large numbers of people employed, contributed the greatest number of individuals with work-related injuries. Two industries had very high rates of specific and preventable injuries--food and fish processing with an estimated 17 knife lacerations per 1000 per annum and mechanical engineering with 60 eye injuries per 1000 per annum. We give reasons for believing that our estimates of risk in the different industrial sectors are conservative.

Accidents, Occupational↗
PubMed1991

Resin-to-enamel bond strengths with various etching times.

It has been advocated recently that etching times of enamel be reduced from 60 seconds to as low as 15 seconds. However, the minimal etching time needed to achieve adequate retention of composite resin to enamel has not been identified. In this study, an attempt was made to find the minimal enamel-etching time that still allowed adequate bond strength of composite resin to enamel surfaces. Adequate bond strength was defined as equivalent to the bond strength established for the conventional 60-second etch. Results seemed to indicate that a 5-second etch was sufficient to allow adequate bond strength; however, further study is required to determine the effects of short etching times on microleakage.

Acid Etching, Dental↗
PubMed1991

A chamber system for maintaining a hyperbaric environment for long-term animal studies.

An experimental hyperbaric chamber system is described whereby animals, including nonhuman primates, can be cared for under altered environmental conditions for periods in excess of 1 wk. The chamber itself is capable of a working pressure of 200 atm abs, used with various mixtures of gases which can be varied independently. The novel approach of vertical mounting enables cages to be lowered into position, and food and water can be supplied from above while excreta can be removed from below, irrespective of the internal pressure. The chamber has an integrated life support system such that temperature, both of the chamber and of the mass of gas inside, humidity, oxygen, carbon dioxide, and noise levels can be accurately and finely controlled, all within a pathogen-free environment.

Animals↗
PubMed1990

Recurrent mutation of immunoglobulin and c-myc genes and differential expression of cell surface antigens occur in variant cell lines derived from a Burkitt lymphoma.

The phenotypic and molecular genetic characteristics of 4 variant sublines of the Burkitt lymphoma cell line Namalwa have been examined. The sublines are DNA-fingerprint-identical and derived from a monoclonal tumour, as shown by a rearrangement of the T-cell-receptor beta-chain gene common to the 4 sublines. There is non-co-ordinate expression of MHC class-I MHC class-II, surface immunoglobulin and a number of antigens recognized by CD MAbs on the different sublines. These different phenotypes of the cells are reminiscent of B cells arrested in varying states of cellular maturity. On Southern blots there are different patterns of restriction fragments hybridizing with Ig heavy- and light-chain gene probes among the sublines, indicating that multiple rearrangements or mutations of Ig genes have occurred in the cells. Different patterns of hybridizing fragments among the sublines were also found by using c-myc probes, implying the existence of different mutations of the c-myc locus. The c-myc mutation found in one of the sublines mapped to the 5' flanking sequence and in another 3' to the c-myc locus. Using the J17BS8 probe, which detects a restriction fragment length polymorphism in the 3' flanking region of the c-myc gene, a 4-fold variation in the gene copy number among the subline was found and one of the sublines was shown to be hemizygous for c-myc. Examination of DNA from early cultures of Namalwa cells showed that the alternations in Ig and c-myc structure had occurred on prolonged culture of the cells.

Antibodies, Monoclonal↗
PubMed1990

Establishment of a karyotypically normal B-chronic lymphocytic leukemia cell line; evidence of leukemic origin by immunoglobulin gene rearrangement.

A new Epstein-Barr virus (EBV) transformed cell line was established from a patient with B-chronic lymphocytic leukemia (B-CLL). The karyotype of the cell line has remained normal for over 12 months in culture; however, identical heavy and light chain immunoglobulin (Ig) gene rearrangements in the patient's blood and the cell line provided evidence that the EBV transformed cells were derived from the neoplastic clone.

Aged↗
PubMed1990

Ventilation and oxygen uptake during escape from a civil aircraft.

To help develop a specification for equipment providing personal respiratory protection in the event of aircraft fire a study was carried out to quantify ventilation and oxygen consumption during escape from a Trident aircraft. Data were gathered using the P.K. Morgan 'Oxylog' apparatus after its response time to rapid changes in inspired to expired oxygen concentration difference was assessed using a bench test. The 'Oxylog' had a lag time of 30-32 s and a 5-95% response typified by a half time of 20 s. The data gathered were corrected in the light of these findings. Fourteen male subjects aged 17-38 years were studied under two conditions. Four mass evacuations each involving 40 people; a total of nine subjects escaping from the front rank over eight seats being monitored. Six evacuations each involving only two people escaping from the rear of the cabin; a total of 11 subjects escaping over 14 seats being monitored. Escape was made over the seat backs, down an escape chute to a position 12 m from the base of the chute. Resting minute ventilation (mean 16.7 1 STPD) and oxygen consumption (mean 0.41 min-1 STPD) were similar before both evacuations. There were no significant differences between the two conditions either during, or up to 180 s after escape. Ventilation and oxygen consumption were greatest in the recovery period. The highest oxygen consumption seen was 2.08 l min-1 and maximum minute ventilation was 641. Mean total oxygen consumption for the escape and a 150 s recovery period was 2.41 l (s.d. 0.64, max. 3.11) for the mass evacuation and 2.97 l (s.d. 0.68, max. 4.09) for the two person evacuation. The mean total amount of gas inhaled during the same time period was 89.3 l (s.d. 25.6, max. 121.3) for the mass evacuation and 99.01 (s.d. 26.2, max. 137.3) for the other. These was no correlation between ventilation or oxygen consumption and either escape time, body weight, height or age.

Accidents, Aviation↗
PubMed1990

A case of G-LOC in a propeller aircraft.

The occurrence of +Gz-induced loss of consciousness (G-LOC) is well recognized in high-performance aircraft. A case of G-LOC is described involving a co-pilot on a flying instructor's course in a propeller-driven aircraft, the CT-4. The cause of G-LOC is attributed to a combination of a lack of recent G exposure, not commanding the aircraft, fatigue, and a possibly less-than-optimal straining manoeuvre. This case reinforces the problems of G-LOC in any aircraft capable of performing aerobatics.

Adult↗
PubMed1989

Molecular evidence for a single clonal origin in biphenotypic concomitant chronic lymphocytic leukemia and multiple myeloma.

To establish the clonal origin of a case of concomitant B-cell chronic lymphocytic leukemia (IgM kappa) and multiple myeloma (IGA lambda), we analyzed the immunoglobulin (Ig) gene rearrangements in the patient's blood and bone marrow. Despite the different isotypes, pretreatment investigation of the heavy chain gene (JH) revealed a germline fragment and two identical rearrangements in the blood and marrow. Both kappa and lambda light-chain genes were rearranged in the blood, suggesting peripheral blood lymphocyte involvement in the myeloma. Analysis of the Ig genes after chemotherapy demonstrated no change in the JH or CK rearrangements; however, the lambda genes were now in a germline configuration. Our results suggest that in this patient both chronic lymphocytic leukemia and myeloma originated from the same B-cell progenitor.

Antigens, Neoplasm↗
PubMed1989

Safety of divers.

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Decompression↗