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Biomedical subjects

A Tait

Publications and source records attributed to A Tait.

At least 127 records · Page 7Linked to original sources
PubMed1987

Control of lymphoproliferation by Theileria annulata.

The economic importance of bovine theilerioses has prompted several new approaches to understanding the diseases in the hope of developing more efficient methods of control. Most Theileria species that infect cattle cause a lymphoproli ferative disease. Sporozoites, injected into the host bloodstream by the tick vectors, rapidly invade host lymphocytes and stimulate rapid division of infected cells. As these rupture, merozoites are released which invade red blood cells ready to infect feeding ticks again. The process by which Theileria parasites can control host lymphocytes, and induce them to divide in synchrony with the parasites themselves, is poorly understood but seems to be the key to pathogenesis. In this article, Michael Dyer and Andrew Tait discuss the possible mechanisms of cellular control in the light of recent work revealing sequences homologous to oncogenes in the DNA of T. annulata.

Journal Article↗
PubMed1986

Antigenic diversity of Theileria annulata macroschizonts.

A series of monoclonal antibodies has been produced which reacts with the intracellular macroschizont of Theileria annulata, and this series has been used to examine the level of antigenic diversity between and within stocks of the parasite in addition to species specificity within the genus. The majority of the monoclonal antibodies (six of eight) reacted with all stocks tested and four were species-specific. Two monoclonal antibodies detected variation between stocks and within stocks. The variation within a stock was manifest as only a proportion of the macroschizonts reacting with the monoclonal antibody. This was demonstrated as being due to the strain containing more than one antigenic type of parasite by cloning the infected lymphocyte cell line and showing that the resulting cloned cell lines were antigenically homogeneous. The variation between stocks allowed them to be divided into three groups on the basis of antigenic profile.

Animals↗
PubMed1986

Identification of infection-associated antigens in Theileria annulata transformed cells.

The protozoan parasite Theileria annulata causes a severe disease of cattle in tropical countries; one stage in the parasite life cycle involves the transformation of bovine lymphocytes leading to rapid lymphoproliferation. Immunity to this disease is largely cell mediated and directed against the infected lymphocyte. In this paper we report the identification of three classes of infection specific antigen (using monoclonal antibodies) one of which is found on the surface of the lymphocyte. Such antigens can be used in parasite strain typing, in providing an understanding of the molecules involved in immunity and in providing the basis for a vaccine.

Animals↗
PubMed1986

Specific lysis of Theileria annulata-infected lymphoblastoid cells by a monoclonal antibody recognizing an infection-associated antigen.

A monoclonal antibody (4H5) recognizing a Theileria annulata infection-associated antigen was assayed to see if it could either suppress the proliferation of T. annulata-infected lymphoblastoid cells, as monitored by the incorporation of tritiated thymidine by proliferating host cells, or lyse T. annulata-infected lymphoblastoid cells, as assessed by counts of target cell numbers and examination of Giemsa stained smears. These assays showed that binding of the monoclonal antibody, in the presence of complement, both lysed and suppressed the proliferation of the T. annulata Hissar-infected cell line against which this monoclonal antibody was raised. This effect extended both to other (allogeneic) T. annulata Hissar-infected cell lines and to lymphoblastoid cell lines infected with other geographical stocks of T. annulata. An uninfected bovine lymphoid cell line was not affected by the antibody. The results obtained in these in vitro experiments are taken to mean that binding of the monoclonal antibody 4H5 to a T. annulata infection-associated antigen, in the presence of complement, will lyse and suppress specifically the proliferation of T. annulata-infected lymphoblastoid cells. These observations raise the possibility that immunization of cattle with the purified T. annulata infection-associated antigen recognized by this monoclonal antibody may provoke immune responses which are capable of suppressing the proliferation of T. annulata-infected lymphoblastoid cells in vivo and thus provide an effective method of immunoprophylaxis against tropical theileriosis.

Animals↗
PubMed1986

Prevalence of hemochromatosis in a random sample of asymptomatic men.

The prevalence of hemochromatosis was studied in 343 randomly selected male World War II veterans aged 58 years and older. Those men with a serum ferritin level of greater than 700 micrograms/l or a transferrin saturation of greater than 55% underwent liver biopsy. Hepatic iron concentration was assessed histochemically and by atomic absorption spectrophotometry. Histology was assessed blindly by one histopathologist. Of 21 veterans biopsied, four men had hemochromatosis, confirmed by venesection response, and the remaining biopsies all showed some histological abnormality. All four men with hemochromatosis had a transferrin saturation of greater than 55% while only three of the four had a serum ferritin level over 700 micrograms/l. The prevalence of hemochromatosis detected in this sample was 1.2%, which is higher than that suggested by overseas studies.

Aged↗
PubMed1985

Enzyme variation in T. brucei ssp. II. Evidence for T. b. rhodesiense being a set of variants of T. b. brucei.

A collection of stocks of Trypanosoma brucei rhodesiense isolated in Kenya have been examined for electrophoretic variation in 20 enzymes. The results obtained have been analysed in order to determine whether these trypanosomes are diploid and undergo mating and to determine the genetic distance between T. b. rhodesiense, T. b. brucei and T. b. gambiense. The enzyme electrophoretic markers were further used in experiments involving cyclically transmitted mixtures of stocks aimed at detecting genetic exchange in the laboratory. No genetic exchange was detected. Two novel features of the enzyme electrophoretic results were found. Firstly, the stocks of T. b. rhodesiense were considerably more homogeneous than equivalent collections of stocks of T. b. brucei and secondly, all the stocks examined were heterozygous for two alleles of alkaline phosphatase and showed an excess of heterozygotes at the phosphoglucomutase locus. The degree to which these features are typical of T. b. rhodesiense has been examined in relation to previously published data. The results obtained strongly support the view that T. b. rhodesiense is a set of variants of T. b. brucei rather than a subspecies and a working hypothesis as to the relationship between T. b. brucei and T. b. rhodesiense is proposed to explain the enzyme electrophoretic data obtained.

Animals↗
PubMed1985

Diet and drinking habits in relation to the development of alcoholic pancreatitis.

To determine whether increased intakes of fat and protein or particular drinking habits are associated with the development of alcoholic pancreatitis, a dietary study has been conducted. Patients with clinically evident alcoholic pancreatitis were compared with individuals with clinically evident alcoholic cirrhosis with respect to dietary and drinking habits before the onset of clinical illness. There was no significant difference between the two groups regarding intake of nutrients, drinking habits or type of alcoholic beverage consumed.

Adult↗
PubMed1984

Evidence for an inherited predisposition to alcoholic pancreatitis. A controlled HLA typing study.

To investigate the role of heredity in alcoholic pancreatitis, an HLA typing study has been performed. Patients with alcoholic pancreatitis exhibited an increased frequency of HLA Bw 39 when compared with the general population [13.6% vs 3.3%, P (corrected) less than 0.02; relative risk 4.7]. Alcoholics without pancreatitis did not differ from the general population with respect to HLA status, indicating that the increased incidence of HLA Bw 39 was related to alcoholic pancreatitis rather than to alcoholism itself. Thus, this study has provided evidence for a genetic predisposition to alcoholic pancreatitis.

Alcoholism↗
PubMed1984

Enzyme variation in Trypanosoma brucei spp. I. Evidence for the sub-speciation of Trypanosoma brucei gambiense.

Three groups of stocks of Trypanosoma brucei ssp, defined by the criteria of host, human serum resistance and place of isolation as T. b. gambiense, T. b. brucei (Nigeria) and T. b. brucei/rhodesiense (non-gambiense, Uganda) were screened for electrophoretic variation at 20 enzyme loci. One enzyme (Peptidase C) was found to differentiate all T. b. gambiense stocks from the other T. brucei stocks and, taken together with specific variants of 5 other enzymes, could be used to unambiguously define T. b. gambiense stocks. Using a population genetics approach, the frequencies of the different variants in the three groups of stocks were estimated and from them the average similarity and difference between groups were measured using the statistics of genetic identity (I) and genetic distance (D). These results show firstly, that T. b. gambiense is more different from the other two groups than they are from each other and, secondly, that the values of I and D obtained are consistent with T. b. gambiense constituting a sub- or sibling species of T. brucei. Three domestic animal isolates from Zaire and Cameroun were also screened for enzyme variation and two of these identified as T. b. gambiense, thereby establishing the existence of an animal reservoir host. In parallel, these stocks were tested for human serum resistance resulting in the same identification. Studies of the antigen repertoires and antigen gene structure were carried out by other workers on all the T. b. gambiense stocks reported here and the same conclusions reached as to the identification and ability to discriminate this subspecies from other groups of T. brucei stocks. The results presented here are discussed in relation to other published data on enzyme variation in T. brucei.

Alleles↗
PubMed1984

A neurological basis for visual discomfort.

Certain patterns of stripes are judged to be unpleasant to look at. They induce illusions of colour, shape and motion that are sometimes perceived predominantly to one side of fixation. People who suffer frequent headaches tend to report more illusions, and if the pain consistently occurs on the same side of the head the illusions tend to be lateralized. The parameters of the patterns that induce illusions (including their shape, spatial frequency, duty cycle, contrast and cortical representation) closely resemble those that elicit epileptiform electroencephalographic abnormalities in patients with photosensitive epilepsy. The viewing conditions under which such abnormalities are likely to appear are also those under which more illusions are seen.

Adolescent↗
PubMed1983

Synthesis and antimicrobial activity of monoalkylcarbamic and thiocarbamic esters of 3-mercapto-1,2,4-benzothiadiazine-1,1-dioxide and of its Bz-derivatives.

A new series of monoalkylcarbamic esters of 3-mercapto-1,2,4-benzothiadiazine-1,1-dioxide (I) and of its 6-chloro- and 5,7-dichloroderivatives [compounds (II leads to XVI)] and a series of monoalkylthiocarbamic esters of (I) [compounds (XVII leads to XIX)] were synthesized and evaluated in vitro for antimicrobial activity. All the substances studied have been found to possess an inhibiting action on one or more strains of mycetes of the genus Candida and on some strains of Gram-positive bacteria belonging to the genus Staphylococcus. Moreover, some compounds have shown a bacteriostatic effect on a strain belonging to the genus Streptococcus. None of the substances tested was active on Gram-negative schizomycetes.

Anti-Bacterial Agents↗
PubMed1983

Antigens of the erythrocytes stages of the human malaria parasite Plasmodium falciparum detected by monoclonal antibodies.

A range of 22 mouse anti-P. falciparum monoclonal antibodies have been characterized by indirect immunofluorescence and immunoprecipitation. On the basis of these studies, 5 groups of antibodies and 6 classes of antigen were defined. Group I antibodies give, bright, uniform, generalised staining of all blood stages including gametocytes. Three of these antibodies precipitate a metabolically labelled molecule(s) of 35 kDa. One precipitates a 50 kDa antigen. Group II antibodies, which give strong localised immunofluorescence in merozoites, and a weak diffuse pattern in earlier stages, precipitate biosynthetically labelled molecules of 160 kDa. Group III antibodies react with all asexual stages. With merozoites they produce intense staining around the perimeter, both in fixed and unfixed preparations. They precipitate biosynthetic molecules of 190 kDa. Group IV antibodies are identical to Group III except they are stage restricted to schizonts and merozoites. They also precipitate 190 kDa antigens. These, however, in contrast to group III, are readily accessible to 125I-lactoperoxidase labelling. One antibody also precipitates a set of smaller peptides. Finally, Group V antibodies produce very bright ill-defined staining of pigment-containing parasites, as well as of inclusions in the red cell. They precipitate a series of molecules of 160, 60 and 35 kDa which are readily accessible to 125I. The 160 kDa molecule is also labelled by [35S]methionine. These results are discussed in the context of the development of a malaria vaccine and immunodiagnostic tests.

Animals↗
PubMed1983

Sexual processes in the kinetoplastida.

The commonly held view that the kinetoplastida, and in particular trypanosomes, are asexual is largely derived from the principle that an organism is asexual until proved sexual. If the basis for this view is examined in detail, it largely arises from the lack of morphologically distinguishable gametes, the difficulties encountered in visualizing chromosomes and a few experiments, using drug-resistant stocks, in which no recombination between stocks could be demonstrated. While it is clear that these organisms are able to reproduce asexually, the existence of a sexual cycle was, until recently, an entirely open question. The early work strongly suggests that any sexual process (in the species examined extensively at the morphological level) does not involve classical well-differentiated gametes and so must involve fusion of morphologically very similar cells. These findings taken together with the inability to visualize chromosomes and thereby identify meiosis, mean that classical methods are unable to detect any sexual process even if it did occur. This review examines the evidence provided by the experimental approaches which have been applied recently to the question of kinetoplastid sexuality. These approaches include isoenzyme studies and the analysis of possible genetic exchange by the use of selective markers (e.g. drug resistance). The results which these techniques have produced make it clear that the kinetoplastid protozoans cannot be regarded as a totally asexual group of organisms.

Animals↗
PubMed1983

The effect of counselling on physical disability and social recovery after mastectomy.

A controlled trial was conducted to determine if a specialist nurse improved the physical and social recovery of patients after mastectomy and helped them adapt to the breast loss. Seventy five patients were counselled by the nurse who also monitored their progress after discharge while 77 patients received the care normally given by the surgical unit. Twelve to eighteen months after surgery those helped by the nurse showed a greater social recovery, return to work, adaptation to breast loss and satisfaction with their breast prostheses. Eleven percent remained distressed by the mastectomy but most responded well to breast reconstruction. The nurse had little impact on physical disability. The morbidity found in the control group highlights the need to find ways of reducing it. While the appointment of a specialist nurse can achieve this the morbidity would probably also be much reduced if the breast was conserved when possible, reliable staging methods other than axillary clearance were developed and the adverse effects of cytotoxic drugs and radiotherapy were reduced.

Adult↗
PubMed1982

Cost of counselling women who undergo mastectomy.

The psychiatric morbidity associated with mastectomy and brest cancer was substantially reduced by a specialist nurse who counselled women before and after surgery and monitored their progress. A controlled study was, therefore, carried out to determine what this cost. National Health Service costs were almost wholly covered by savings made because counselled subjects who developed psychiatric problems were recognised and treated much earlier than control patients. Counselled and control subjects suffered considerable financial losses, but these were offset in the counselled group by their relatives' earlier return to work. Such counselling schemes are necessary and effective and may be implemented at little extra cost.

Community Health Services↗