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Biomedical subjects

J Clark

Publications and source records attributed to J Clark.

At least 415 records · Page 23Linked to original sources
PubMed1983

Harvesting and subculturing cells growing on denatured-collagen coated microcarriers (Cytodex 3).

Selecting correct procedures and conditions for harvesting cells was essential for successful subcultivation of cells when using the microcarrier culture technique. The proteolytic enzymes trypsin, Dispase and collagenase were compared with respect to the yield and the viability of Vero cells when harvested from Cytodex 3 microcarriers. Treatment with Dispase or trypsin resulted in similar viabilities but recovery after trypsin treatment was improved. The advantage of using collagenase was the improved plating efficiency of cells when subculturing to new microcarrier cultures. Pre-washing the confluent microcarriers with EDTA (0.02% w/v) improved the yield and the viability when harvesting with trypsin or collagenase. The stage of the culture cycle when cells were harvested did not influence relative recovery or viability. In contrast, significant differences in recovery and viability were found when harvesting cells grown in the presence of different batches of foetal calf serum. The results confirm that the choice of enzyme for harvesting depends upon the cell type and purpose of the culture.

Animals↗
PubMed1983

Pancreatoduodenectomy for resectable malignant periampullary tumors.

The results of all 53 pancreatoduodenectomies performed at one hospital were reviewed for operative mortality, accuracy of operative diagnosis and long term survival. Although carcinomas of the ampulla are much more rare than those of the pancreas, the number of patients in our operative series with adenocarcinoma of the ampulla approached the number with adenocarcinoma of the pancreas, indicating that only those with small, early lesions of the head of the pancreas were considered to be appropriate candidates for pancreatoduodenectomy. Six of the 21 patients with carcinomas of the pancreas had histologically favorable tumors (three papillary adenocarcinomas, two cystadenocarcinomas and one islet cell carcinoma), although only one of these was correctly diagnosed preoperatively or intraoperatively. Eight patients had benign conditions, half of whom underwent planned resections for chronic pancreatitis. The over-all operative mortality for our series was 13.2 per cent. The operative diagnosis was incorrect in seven patients. Excluding cystadenocarcinomas and islet cell carcinomas, four patients with carcinoma of the pancreas survived five years and six patients with carcinoma of the ampulla survived five years, with corresponding survival periods of 2.5 and 5.1 years following pancreatoduodenectomy. We conclude that: 1, pancreatoduodenectomy should be used in a highly selective manner by surgeons experienced with such operations; 2, the high diagnostic error rate and the occurrence of histologically favorable tumors of the pancreas make the arbitrary exclusion of all tumors of the pancreas for resectional therapy an unsound policy, and 3, pancreatoduodenectomy remains the best therapy for resectable tumors of the periampullary region.

Adenocarcinoma↗
PubMed1983

The dose of house dust mite antigen (P1) inhaled by infants aged one month.

A survey of the habitats occupied by 12 infants of one month of age revealed that approximately 10% of their day was spent in conditions of potential exposure to the major (P1) allergen of the house dust mite, Dermatophagoides pteronyssinus. A respiratory pump which reproduced the minute ventilation of an infant was placed in representative infant habitats. The P1 allergen trapped by the filter in this pump was measured as an estimate of infants' allergen intake. Detectable P1 intake was only present when there was active air disturbance (bed making and vacuuming). The average P1 intake was approximately 3 ng P1/24 hours. Comparison of this P1 intake with that which sensitizes in other situations suggests that it is usually inadequate to sensitize infants.

Allergens↗
PubMed1983

Percentage malignant involvement: a new concept in staging of breast cancer.

All the recognised systems of clinical staging of breast cancer have failed to provide reliable prognostic estimates of survival since they do not accurately reflect the pathological extent of the disease. In this prospective study of 52 female patients with established primary breast cancer we have measured the percentage neoplastic involvement of the breast at the time of mastectomy. This correlated well with the histological axillary node status, the subsequent development of overt metastatic disease, and survival during a follow-up period of 28-54 months.

Adult↗
PubMed1982

Relation between regional myocardial uptake of rubidium-82 and perfusion: absolute reduction of cation uptake in ischemia.

Experiments were undertaken using rubidium-82 and position tomography to examine the relation between myocardial perfusion and cation uptake during acute ischemia. Rubidium-82 was repeatedly eluted from a strontium-82-rubidium-82 generator. In six dogs emission tomograms were used to measure the delivered arterial and myocardial concentrations at rest and after coronary stenosis, stress and ischemia. There was a poor overall relation between regional myocardial uptake and flow measured by microspheres and a large individual variability. Extraction of rubidium-82 was inversely related to flow. Significant regional reduction of cation uptake was detected in the tomograms when regional flow decreased by more than 35 percent. This reduction was significantly greater when ischemia was present. A small but significantly greater when ischemia was present. A small but significant decrease (33.0 +/- 9.1 percent, mean +/- standard deviation) in the myocardial uptake of rubidium-82 was detected only when flow was increased by more than 120 percent in relation to a control area after administration of dypiridamole. The technique using rubidum-82 and tomography was applied in five volunteers and five patients with angina pectoris and coronary artery disease. Myocardial tomograms recorded at rest and after exercise in the volunteers showed homogeneous uptake of cation in reproducible and repeatable scans. In contrast, the patients with coronary artery disease showed an absolute mean decrease of 36 +/- 14 percent in regional myocardial uptake of rubidium-82 after exercise. These abnormalities persisted in serial tomograms for more than 20 minutes after the symptoms and electrocardiographic signs of ischemia.

Adult↗
PubMed1982

Septal lesions and active avoidance performance in rats: effects of differential intrabox cues.

In two separate experiments, male rats received septal lesions and were compared to operated controls on the acquisition of a two-way active avoidance task. In both experiments, an automated active avoidance apparatus (Lafayette Instrument Co.) was used, and the animals were tested 10 trials each day, 6 days/week. The CS was a tone, and the US was a 0.7 mA shock; the CS-US interval was 7 seconds. In Experiment 1, the rats (N = 6/group) were tested under conventional conditions. The two compartments of the avoidance apparatus were identical in all respects. In Experiment 2, the rats (N = 6/group) were tested in the same apparatus, but with differential intrabox cues. The inside of the left compartment was lined with black contact paper, while the inside of the right compartment was lined with white contact paper. Irrespective of the conditions, the septal rats were facilitated in the acquisition of shuttle-avoidance. In both tasks, the septal subjects required fewer trials to reach criterion, and showed better orientation in the shuttle-box compared to controls. The response latencies of the septal subjects also tended to be faster, but neither septal nor control subjects showed differential response latencies related to the direction of the shuttle response. Previous findings have shown that the addition of external cues to purported spatial tasks can reduce the behavioral effects produced by damage to the septohippocampal axis on such tasks. The present results suggest that such a cue-addition procedure does not influence the behavioral effects produced by septal lesions in shuttle-avoidance.

Animals↗
PubMed1982

Early and delayed shut-off of host protein synthesis in cells infected with herpes simplex virus.

A mutant of herpes simplex virus type 1 [HSV-1(HFEM)], tsB7, appears to have two temperature-sensitive functions. One is required during the first hour of infecting a cell (suggesting that it is performed by a virion protein) and the other is the non-essential function of "early shut-off" of cellular protein synthesis, which is mediated by a virion protein. The latter function remained temperature-sensitive in a revertant virus (RC2) grown at the non-permissive temperature (39 degrees C). However, under these conditions RC2 did cause inhibition of host synthesis, showing that "delayed shut-off", requiring virus protein synthesis, can occur independently of early shut-off, which is mediated by a virion protein. Early shut-off by u.v.-irradiated tsB7 was reversed when the temperature was raised, whereas delayed shut-off by intact tsB7 was not. Of two wild-type strains of virus examined, HSV-1(F) also exhibited temperature-sensitive early shut-off, but HSV-2(G) did not.

Animals↗
PubMed1982

Atypical T lymphoproliferative disorder demonstrating in vitro suppressor and helper characteristics.

A patient initially diagnosed on surface marker status as having T cell chronic lymphatic leukaemia (T-CLL) was found to have arthropathy and recurrent pulmonary infarction associated with a high anti-DNA antibody titre. The T cell from this patient, on assessment in an in vitro pokeweed mitogen driven B cell system, demonstrated suppressor and helper characteristics but lacked antibody dependent cellular cytotoxicity (ADCC) activity and natural killer (NK) activity. Using peripheral blood mononuclear cells (PBM) from patients with Hashimoto's thyroiditis and normals, it was shown that the patient's T cells suppressed both IgG and thyroid autoantibody production. Irradiation of the patient's PBM inhibited the suppressor effect and a residual helper effect remained. The patient was treated with systemic steroids for exacerbations of arthropathy which caused a fall in lymphocyte count. After 36 months the DNA binding activity spontaneously improved and the lymphocytosis disappeared. It is indicated that T-cell proliferations demonstrating functional activity must be assessed within the context of any underlying non-haematological clinical and laboratory findings.

Adult↗
PubMed1982

House dust mites in Bristol.

A survey of bedding in Bristol revealed reducing mite concentrations on children's toys, mattresses, overblankets and pillows. Dermatophagoides pteronyssinus was the commonest mite found. A vacuuming schedule was devised for removing mites so that a double blind trial could be carried out. Investigation suggests that even with expert utilization of efficient vacuum cleaners the clinical efficacy would be limited as the mites appear to rapidly migrate back into the bedding.

Allergens↗
PubMed1982

Development of models and theories on the concept of nursing.

This paper shows how models can be used by practitioners of nursing as a practical tool to analyse their own practice, in particular to assess needs and to plan, implement, and evaluate care. It is argued that the impact of existing work in theory development has been relatively small, at least in the UK, because the theories are not sufficiently specific to everyday nursing activities and the models are over elaborate and not universally applicable. A simple model of nursing, based on a systems approach is presented and applied to one particular field of nursing practice, i.e. health visiting. The model, which can be used in any field of nursing, stresses the reciprocity of the nurse-patient relationship, and the significance of the environment in determining the concepts of nurse, patient and nursing.

Adult↗
PubMed1981

Scintiscanning of the breast with 99Tcm-diethylene triamine penta-acetic acid--a prospective blind evaluation.

In this blind prospective study of breast scintiscanning with 99Tcm-diethylene triamine penta-acetic acid (DTPA) in 67 female patients presenting at a primary breast referral clinic, we have observed that this investigation has a high diagnostic accuracy in distinguishing benign from malignant lesions of the breast. The predictive value of the test when positive in establishing the presence of cancer is 94 per cent with a false negative rate of 6 per cent. The predictive value of the test when negative in excluding cancer in 97 per cent with a false positive rate of 3 per cent. Initial studies also indicate the potential value of DTPA breast scintiscanning in delineating the activity of painful benign lesions of the breast.

Adult↗