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Biomedical subjects

B Roberts

Publications and source records attributed to B Roberts.

At least 145 records · Page 8Linked to original sources
PubMed1988

Acute myeloid leukemia in adults: a case-control study in Yorkshire.

This paper reports the results of a case-control analysis of 161 cases of acute myeloid leukemia and 310 matched hospital controls. The patients were interviewed between 1982 and 1986. The study shows a weak association for cases with previous malignant disease. Furnace workers show excess risks. Urticaria and vertigo are in excess, as well as some aspects of family medical histories, including multiple sclerosis and cases of leukemia/lymphoma in blood relations.

Adult↗
PubMed1987

Infective complications of plasma exchange: a prospective study.

We examined the incidence and types of infective complications which occurred in 41 patients whose medical management included plasma exchange (PX) by intermittent cannulation; femoral, subclavian, or internal jugular catheter; or arteriovenous shunt. A high incidence of positive cultures from vascular access catheters was demonstrated. Of 23 patients for whom data were available, 13 had positive cultures, and results on 3 of these showed greater than 1 species. Gram-positive cocci were typically found. Of the 34 patients who received drug immunosuppression with PX, 1 patient developed severe shunt-site infection, and an additional 4 developed bacteremia. Seven patients were given PX alone, and none of these developed clinically significant infection; however, this difference in infection rate did not reach statistical significance. Clinically significant access-related infection remains an infrequent but potentially important hazard of therapeutic PX.

Adolescent↗
PubMed1987

Chronic lymphocytic leukaemia: case control epidemiological study in Yorkshire.

This is the second report of a large case control study of lymphoma/leukaemia occurring in Yorkshire during 1979-84, and deals with chronic lymphocytic leukaemia presenting either in its haematological (CLL) or more solid lymphomatous (malignant lymphoma-lymphocytic or MLL) forms. In all, 330 cases and 561 controls were interviewed. The results support the concept that CLL/MLL is a condition of multiple aetiologies with evidence for genetic predisposition through an excess of family cases, immune perturbation demonstrated by excessive previous skin diseases and phenylbutazone use, and viral involvement shown by links with infectious diseases and multiple sclerosis.

Drug-Related Side Effects and Adverse Reactions↗
PubMed1987

Variation in lymphoma incidence within Yorkshire Health Region.

The spatial distribution of new cases of lymphoma occurring in Yorkshire between 1978 and 1982 has been studied. Administrative districts were used as the basis for analysis and differences in age standardised incidence rates between districts were determined. Excessive rates for NHL were found to occur in Scarborough, York and Leeds districts. In addition an analysis contrasting broadly urban and rural districts showed an excess of NHL in rural areas, particularly of the follicular subtypes.

Adolescent↗
PubMed1987

Spatial patterns in electoral wards with high lymphoma incidence in Yorkshire health region.

The possibilities of clustering between those electoral wards which display higher than expected incidences of cases of the lymphomas occurring between 1978 and 1982 are examined. Clusters are defined as being those wards with cases in excess (at a probability of less than 10%) which are geographically adjacent to each other. A separate analysis extends the definition of cluster to include high incidence wards that are adjacent or separated by one other ward. The results indicate that many high incidence lymphoma wards do occur close together and when computer simulations are used to compute expected results, many of the observed results are shown to be highly improbable both in the overall number of clustering wards and in the largest number of wards comprising a 'cluster'.

Computer Simulation↗
PubMed1987

Hodgkin's disease: case control epidemiological study in Yorkshire.

This is the first report of a case-control epidemiological study on lymphomas and leukaemias occurring in Yorkshire during 1979-84. This paper deals with the results of the Hodgkin's disease analysis comprising 248 cases and 489 controls. The results indicate support for previous work with respect to small family size and past history of infectious mononucleosis. Positive observations made in a previous pilot study are also confirmed and extended with respect to associations with certain chronic skin lesions, dental anaesthesia and familial factors. Negative associations are described with respect to X-ray exposures and cigarette smoking. It is proposed that these results fit into a general hypothesis that these conditions are the result of interaction between infectious agents and altered immunity in those persons genetically predisposed.

Adolescent↗
PubMed1986

Ring gland and prothoracic gland sensitivity to interspecific prothoracicotropic hormone extracts.

Using the techniques of intraspecific in vitro activation of prothoracic glands and ring glands by serial dilutions of prothoracicotropic hormone (PTTH) extracts from pupal Manduca sexta (Lepidoptera) and larval Sarcophaga bullata (Diptera), a dose-response of activation was observed for both species. In both species maximum activation was at 0.5 brain equivalents while the number of brain equivalents necessary for half maximal stimulation (ED50) was 0.20 for Manduca and 0.15 for Sarcophaga. When prothoracic glands or ring glands were challenged with interspecific PTTH extracts from a stage different from that of the gland donor, no dose-response of gland activation was observed. However, when M. sexta larval prothoracic glands were challenged by S. bullata larval PTTH extract, activation was observed. The dose-response profile fell midway between the dose-response curves obtained for the intraspecific assays. Thus, PTTH extract from one insect has the ability to activate the prothoracic glands of an insect representing another order.

Animals↗
PubMed1986

Rising incidence of lymphoid malignancies--true or false?

The report contrasts the ascertainment of cases by the regional cancer registry with a specially designed search for records and pathology material which was then submitted to critical review irrespective of the original diagnosis. Boundary changes over the intervening years were accounted for and the results contrasted between time periods and with the cancer registry records. A large proportion of cancer registry cases were never subjected to histopathological diagnosis and comparisons between the new data and records are not easy to undertake. The study describes a probable true rise in the incidence of follicular non-Hodgkin's lymphoma in certain parts of Yorkshire over the last 20 years; there is less evidence of a similar change in Hodgkin's disease incidence over the same period of time.

Adolescent↗
PubMed1985

The purification and kinetic characterization of eel white muscle pyruvate kinase.

A stable, homogeneous preparation of pyruvate kinase from white muscle of the American eel, Anguilla rostrata with a specific activity of 350 units/mg has been obtained. The enzyme has a pH optimum in the range 6.3-6.5 and requires Mg2+ and K+ for maximum activity. Eel muscle pyruvate kinase exhibits slight co-operativity in the binding of the substrate phosphoenol-pyruvate. It is activated by fructose-1,6-bisphosphate in a pH dependent manner and is inhibited by both alanine and phenylalanine. These properties are very similar to the properties of the mammalian M2 isozyme.

Anguilla↗
PubMed1985

Serum valine, methionine and isoleucine levels in patients anaesthetized with and without nitrous oxide.

Serum methionine and valine have been assayed microbiologically in 31 patients anaesthetized with and in 13 controls anaesthetized without nitrous oxide. Isoleucine has been similarly assayed in five cases and three controls. The preinduction levels of both methionine and valine were considerably below those of semifasting healthy adults. Serum methionine fell significantly in both groups as did valine and isoleucine in the controls. These findings are attributed to dietary restriction before and during the operation. Serum valine was significantly elevated in patients anaesthetized with nitrous oxide but only in those anaesthetized for 3 h or longer. Isoleucine also was elevated in two of the five cases exposed to nitrous oxide. Reasons are given for attributing these elevated levels to the direct action of nitrous oxide. Valine is entirely and isoleucine is partly catabolized along the adenosylcobalamin dependent propionyl-CoA-succinyl-CoA pathway. It is concluded that their elevated levels are caused by the inactivation of adenosylcobalamin by nitrous oxide thereby inducing the methylmalonyl mutase block in this pathway. It is suggested also that the relief of this block by adenosylcobalamin in pernicious anaemia could provide a possible metabolic basis for the well recognized early subjective improvement encountered in this disease following vitamin B12 therapy.

Adolescent↗
PubMed1985

Studies of toxic gas production during actual structural fires in the Dallas area.

Gases produced during structural fires were studied as to their potential toxicities. Carbon monoxide was the only gas measured in concentrations considered to be lethal within a short period of time. No correlations were found between gases produced and materials burning. However, significant correlations were discovered between gases produced and the physical aspects of the fire (intensity, burning rate, and the like). The organic compounds identified within the gases gave insight as to another potential health hazard not yet considered. These organic compounds are the products of free radical reactions and as free radicals their potential as toxics is enormous.

Fires↗
PubMed1984

In vitro activity of dipteran ring glands and activation by the prothoracicotropic hormone.

The relationship between hemolymph ecdysteroid titer, ring gland (RG) activity, and prothoracicotropic hormone (PTTH) activation of RG in vitro has been examined during the postfeeding larval, prepupal, and pupal stages of Sarcophaga bullata. Using the ecdysteroid radioimmunoassay (RIA), two significant peaks were recorded during the red spiracular stage and during the first few hours after the formation of the white prepupa and a third large peak 9 hr later. It is postulated that these increases in ecdysteroid titer are involved in the processes of pupariation, puparial tanning, and pupation, respectively. Ring glands isolated from Sarcophaga of known ages were incubated in vitro and the secreted ecdysone was quantified by RIA. Ring glands from early red spiracular stage larvae proved to be the most active and subsequent secretory activity of the RG oscillated every 4 hr with the oscillations gradually decreasing in amplitude. RG activity returned to a basal level 24 hr after formation of the white prepupa, about the time that the hemolymph ecdysteroid titer fell to its basal level. To demonstrate PTTH activity in vitro, brains from 3- to 4-hr prepupae were chosen to activate ring glands from postfeeding larvae. Using a graded series of dilutions of PTTH extract it was shown that a dose-response relationship could be obtained for Sarcophaga similar to that demonstrated or the Manduca sexta PTTH-prothoracic gland system. In Sarcophaga maximal activation resulted in a 10-fold increase in ecdysone synthesis and secretion by ring glands stimulated with 0.5 brain eq. Half-maximal stimulation was attained with 0.2 brain eq of PTTH extract.

Animals↗
PubMed1984

Refining the measurement of psychophysical tuning curves.

Four experiments were performed in an attempt to refine the measurement of psychophysical tuning curves (PTCs). PTCs were determined using sinusoidal signals and narrow-band noise maskers, in both simultaneous and forward masking. In experiment I a fixed low-level notched noise was gated with the masker in order to restrict off-frequency listening and to eliminate "confusions" between the signal and masker in forward masking. In contrast to previous work, this procedure produced PTCs with similar round tips in both simultaneous and forward masking. The PTCs differed mainly in that the high-frequency skirts were steeper in forward masking. Experiment II compared PTCs with and without an additional notched-noise masker, for a number of signal levels. The notched noise had the effect of broadening the tips of the PTCs, this effect being greater in forward masking than in simultaneous masking. With increasing signal level the high-frequency skirt of the PTC became slightly steeper, and the low-frequency skirt slightly shallower. Experiment III studied the effect of signal duration on PTCs determined in simultaneous masking. Duration had little effect when off-frequency listening was restricted with a fixed notched-noise masker, but had a substantial effect in the absence of such a masker. Experiment IV studied the effect of signal delay in forward masking. When off-frequency listening was restricted and the signal levels adjusted to produce similar masker levels at threshold for each delay, the shape of the PTC was not affected by delay. It is concluded that, when PTCs are determined in the presence of notched noise, suppression is probably responsible for most of the differences between simultaneous and forward masking. Previous work may have overestimated the influence of suppression, because it did not control off-frequency listening and/or provide appropriate detection cues in forward masking.

Adult↗