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Biomedical subjects

M J Robertson

Publications and source records attributed to M J Robertson.

103 records · Page 6Linked to original sources
PubMed1980

The actions of dopamine and of sulpiride on regional blood flows in the rat kidney.

1. Blood flow was measured in the renal cortex and medulla of anaesthetized rats by the hydrogen washout method. The effects of dopamine infusion were measured. 2. Low doses of dopamine (20 and 65 n-mole.kg-1.min-1) caused only small increases in renal blood flow, and a higher dose (200 n-mole.kg-1.min-1) caused vasoconstriction. After alpha-blockade with phenoxybenzamine (9 mumole.kg-1), all doses of dopamine caused vasodilatation in the cortex and medulla of the kidney. 3. This dopamine-induced renal vasodilatation was almost abolished by sulpiride (0.7 mumole.kg-1.min-1), but was only slightly attenuated by propranolol (10 mumole.kg-1). 4. Sulpiride did not significantly alter the renal blood flow responses to noradrenaline or isoprenaline, or the blood pressure responses to histamine, acetylcholine, 5HT, noradrenaline and isoprenaline. 5. In normal rats, infusion of sulpiride generally caused a reduction in renal cortical blood flow. This response showed a positive correlation with the initial blood pressure. 6. It is concluded that there are specific dopamine receptors in the renal vasculature of the rat, and that dopamine may play a role in the normal control of renal blood flow.

Animals↗
PubMed1974

Diagnostic electron microscopy of faeces. II. Acute gastroenteritis associated with reovirus-like particles.

Virus particles resembling reoviruses or orbiviruses were found in the faeces of 40 of 73 patients under 6 years of age with acute gastroenteritis and in faeces of only two babies among 31 patients under 6 years admitted to hospital with other diagnoses. In morphology the particles resemble orbiviruses more closely than reoviruses, but differ in appearance from the orbiviruses in having a smooth, circular outline with a well marked continuous rim as seen in negatively stained preparations. They appear not to be serologically related to reovirus types 1, 2, or 3 and may be members of a new group.

Acute Disease↗
PubMed1968

Cholera case investigation and the detection and treatment of cholera carriers in Hong Kong.

Between 1961 and 1966 cholera cases occurred in Hong Kong in each year except 1965. During this period each case was extensively investigated in order to detect carriers among the contacts.In 1961 investigations were confined to the home of the patient but it was found that a much more extensive investigation was required to get epidemiological information of real value. From 1962 onwards the investigations were extended to include the patient's place of employment or school and any eating-place visited by the patient in the 7 days before the onset of disease.Detection of carriers has been a relatively simple procedure in Hong Kong as it has been the policy to isolate all contacts of a cholera case in a quarantine centre. In 1961 three rectal swabs were taken to detect carriers; this was increased to 5 in 1962 and now 7 consecutive daily swabs are considered necessary. Oral streptomycin is regarded as the best treatment for carriers because it is relatively cheap, it produces no side-effects, treatment can be completed in one day and vibrio resistance to the drug is unlikely.As detailed case investigation is expensive, however, it should be undertaken only if the object is to determine the source of the infection. This object was achieved in Hong Kong on only 6 occasions during the period under review. Isolation of the contacts was of little value in comparison with the disruption of family life and the expense involved. Although regular nightsoil sampling was a good indicator of the presence of the disease, the back-tracing of positive samples occupied facilities and staff which could have been better used in case investigation.

Carrier State↗
PubMedDate not supplied

Concurrent validity of negative symptom assessments in treatment refractory schizophrenia: relationship between interview-based ratings and inpatient ward observations.

The concurrent validity of interview-based ratings of negative symptoms in 35 inpatients with chronic, treatment refractory schizophrenia was evaluated. Correlations were examined between interview-based ratings of negative symptoms, measured by the Brief Psychiatric Rating Scale and the Positive and Negative Syndrome Scale, and the naturalistic behavior of inpatients as assessed by the Time Sample Behavior Checklist. Higher levels of interview-based negative symptoms were related to reduced interpersonal activity on the inpatient ward, but not to entertainment, instrumental or self-maintenance activities. These findings offer partial support for the concurrent validity of office-based ratings of negative symptoms, and highlight the importance of longitudinal observations of patients for accurate identification of negative symptoms.

Adolescent↗
PubMedDate not supplied

Costimulation of human natural killer cell proliferation: role of accessory cytokines and cell contact-dependent signals.

Despite the importance of natural killer (NK) cells in the immune response, the regulation of human NK cell growth has not been well characterized. We have hypothesized that, similar to the proliferation of T and B lymphocytes, optimal proliferation of NK cells requires costimulatory signals as well as a primary mitogenic stimulus. Evidence for costimulation by both soluble cytokines and cell contact-dependent factors is presented. Soluble IL-1 and TNF were found to augment NK cell proliferation in response to primary mitogenic cytokines, including IL-2, IL-4, IL-7, and IL-12. The costimulatory effect of IL-1 and TNF is strongly enhanced by the calcium ionophore ionomycin. Coculture of NK cells with irradiated K562 cells can largely substitute for the costimulatory signal provided by ionomycin. Costimulation by K562 requires intimate cell contact and is not reconstituted by cell-free supernatants. Activated T lymphocytes can also mediate contact-dependent costimulation of NK cells; resting PBMC, several NK-sensitive cell lines, and all NK-resistant cell lines tested were not found to be costimulatory. Engagement of CD16 did not augment NK cell proliferation. Thus, triggering of natural killing or antibody-dependent cell-mediated cytotoxicity (ADCC) does not consistently provide a costimulatory signal for NK cell proliferation. Cell contact-dependent costimulation of NK cells does not appear to involve known receptors that can costimulate T cells, including CD2, CD27, CD28, CD29, or LFA-1. The molecular nature of the putative NK cell costimulatory receptor remains to be elucidated. Nevertheless, human NK cells could be expanded in vitro using leukocyte-conditioned medium (LCM) as a source of IL-2 and accessory cytokines and ionomycin to bypass the putative receptor for cell contact-dependent costimulation. NK cells expanded in LCM and ionomycin express typical NK cell antigens and mediate natural killing and ADCC. Further characterization of the costimulatory signals for NK cell proliferation may elucidate the physiologic regulation of NK cell growth and may ultimately allow more effective manipulation of these lymphocytes in the immunotherapy of human diseases.

Antibody-Dependent Cell Cytotoxicity↗