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Biomedical subjects

R Cummins

Publications and source records attributed to R Cummins.

At least 19 recordsLinked to original sources
PubMed2000

Involvement of energy metabolism in the production of 'bystander effects' by radiation.

These experiments were done to determine if interference with energy metabolism and REDOX biochemistry during low LET radiation exposure would alter the ability of medium harvested from the irradiated cells to induce a bystander effect in unirradiated cells. Human keratinocyte cells and CHO-K1 mutant cell lines were irradiated using cobalt 60. Clonogenic assays were used to determine the reproductive death of the cells exposed to direct irradiation or medium from irradiated cells. The persistence in progeny was also examined. Use of apoptosis inhibitors or medium from the LDH or G6PD null cell lines, reduced or prevented the bystander effect. Transfection with G6PD recovered the effect. Treatment with anti-oxidant substances, L-lactate and L-deprenyl prevented bystander factor associated cell kill. The lactate analogue, oxamate, was less effective. Data from experiments where media harvested from the different cell lines was exchanged suggest that signal production and cellular response may involve different mechanisms. The effects on exposed cells were transmitted to progeny which also showed excessive levels of cell death for several generations. The results suggest that energy/REDOX metabolism may be involved in the expression of a radiation induced bystander response. Given the aberrant energy metabolism in tumour cells, this may have implications for dose escalation in radiotherapy.

Animals↗
PubMed2000

Tuberculosis of the breast presenting as carcinoma.

Breast infections caused by Mycobacterium tuberculosis, although rare in western countries, should not be forgotten as a cause of a breast lump presenting clinically and radiologically as a carcinoma in the older patient who gives a history of previous tuberculosis. We report the case of an 84-year-old woman with a breast lump showing noncaseating granulomas on histology who developed a sinus track after excision biopsy of the lump. The patient responded to empiric treatment with anti-tuberculosis drugs and remains well 2 years after presentation.

Aged↗
PubMed1999

Biological preparedness and evolutionary explanation.

It is commonly supposed that evolutionary explanations of cognitive phenomena involve the assumption that the capacities to be explained are both innate and modular. This is understandable: independent selection of a trait requires that it be both heritable and largely decoupled from other 'nearby' traits. Cognitive capacities realized as innate modules would certainly satisfy these contraints. A viable evolutionary cognitive psychology, however, requires neither extreme nativism nor modularity, though it is consistent with both. In this paper, we seek to show that rather weak assumptions about innateness and modularity are consistent with evolutionary explanations of cognitive capacities. Evolutionary pressures can affect the degree to which the development of a capacity is canalized by biasing acquisition/learning in ways that favor development of concepts and capacities that proved adaptive to an organism's ancestors.

Animals↗
PubMed1998

Visual behaviour and dyadic interaction between people with intellectual disability and people who are non-disabled.

Patterns of visual dominance in human interaction have been studied by a number of authors. The purpose of the present research was to investigate the implications of these studies for interaction between people who are disabled and people who are non-disabled. It was predicted that disability would differentiate the two groups, with non-disabled partners dominating the visual interaction. Two studies are reported. The first looked at visual interaction through the two looking modes of looking while listening and looking while speaking between 16 dyads where one partner was intellectually disabled and the other non-disabled. In the second study, eight subjects who were intellectually disabled and who had participated in the first study interacted with another person who had an intellectual disability. Their looking modes were then compared between conversing with a non-disabled partner in study 1 and with those of their partner with intellectual disability in study 2. The outcome of the studies showed that subjects who were intellectually disabled did not discriminate in looking mode between partners of different intellectual levels. Conversely, subjects who were non-disabled spoke and looked significantly more when conversing with their partner who was intellectually disabled. It has been argued that overlooking and overspeaking could arise from the need for the non-disabled person to gain some sign of affiliation from their partner, or alternatively, that it might reflect a dominant non-disabled person attempting to facilitate a cooperative style.

Adolescent↗
PubMed1996

Future directions for resuscitation research. I. Advanced airway control measures.

The efficacy of 'basic' airway control without equipment, using the combination of backward tilt of the head, forward displacement of the mandible, and separation of lips and teeth (i.e. the triple airway maneuver) has been well established. Direct mouth-to-mouth and mouth-to-nose ventilation must continue to be taught to the public. Further improvements are needed for pocket-size mouth-to-mouth barriers to combat infection risks. Dissemination of appropriate information on disease transmission is needed to ensure ventilation by health professionals, using exhaled air ventilation adjuncts and other devices. Much knowledge exists about the pathophysiology of airway obstruction. For patients in coma or anesthesia with airway obstruction, which resists basic airway control measures and standard tracheal intubation, available 'advanced' airway control measures should be mastered and improved. Preparedness for advanced airway control measures differs between elective management of the anticipated difficult airway for anesthesia and emergency airway control with unanticipated difficulties encountered during the ordinary sequential application of measures. Challenges include education research and development of new devices. For airway clearing, pharyngeal intubation, difficult tracheal intubation, cricothyrotomy, transtracheal jet ventilation and emergency use of oxygen - what could and should be taught, to whom, and how? Which new devices and training systems should be developed? The most important alternative to orotracheal or nasotracheal intubation recommended for the development of novel devices and teaching methods for health professionals, are cricothyrotomy (with wide enough airway to also enable spontaneous breathing of air), and translaryngeal or transtracheal oxygen jet ventilation. We recommend openness in communication and joint planning between anesthesiologists, emergency care providers, and appropriate educators, engineers and industries.

Cardiopulmonary Resuscitation↗
PubMed1990

Social insecurity, anxiety, and stressful events as antecedents of depressive symptoms.

This study examined the combined effects on 132 normal adults of social insecurity, anxiety symptoms, and daily hassles on changes in the level of depressive symptoms over a 1-month period. It was hypothesized that social insecurity, a factor linked to coronary heart disease and sympathetic arousal, is also an important antecedent of depression for those who have experienced a high level of anxiety and chronic stress. Results of multiple regression analysis indicate that these three factors in combination (a 3-way interaction) predict changes in depressive symptoms. The nature of this interaction was more complex than hypothesized.

Adult↗
PubMed1989

Reversible middle cerebral artery occlusion without craniectomy in rats.

To develop a simple, relatively noninvasive small-animal model of reversible regional cerebral ischemia, we tested various methods of inducing infarction in the territory of the right middle cerebral artery (MCA) by extracranial vascular occlusion in rats. In preliminary studies, 60 rats were anesthetized with ketamine and different combinations of vessels were occluded; blood pressure and arterial blood gases were monitored. Neurologic deficit, mortality rate, gross pathology, and in some instances, electroencephalogram and histochemical staining results were evaluated in all surviving rats. The principal procedure consisted of introducing a 4-0 nylon intraluminal suture into the cervical internal carotid artery (ICA) and advancing it intracranially to block blood flow into the MCA; collateral blood flow was reduced by interrupting all branches of the external carotid artery (ECA) and all extracranial branches of the ICA. In some groups of rats, bilateral vertebral or contralateral carotid artery occlusion was also performed. India ink perfusion studies in 20 rats documented blockage of MCA blood flow in 14 rats subjected to permanent occlusion and the restoration of blood flow to the MCA territory in six rats after withdrawal of the suture from the ICA. The best method of MCA occlusion was then selected for further confirmatory studies, including histologic examination, in five additional groups of rats anesthetized with halothane. Seven of eight rats that underwent permanent occlusion of the MCA had resolving moderately severe neurologic deficits (Grade 2 of 4) and unilateral infarcts averaging 37.6 +/- 5.5% of the coronal sectional area at 72 hours after the onset of occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Identification of cardiac arrest by emergency dispatchers.

Prompt identification of cardiac arrest by emergency dispatchers can save valuable time and increase the likelihood of successful resuscitation. The authors reviewed 516 cardiac and 146 non-cardiac calls to identify features of a probable cardiac arrest call. The results indicate that information about sex, location, and activity is of little use in the identification of cardiac arrest. When the patient is over 50 years old and the caller is emotional, the possibility of cardiac arrest is high, suggesting that questions about consciousness and breathing should be asked immediately. Additional information can be obtained or telephone cardiopulmonary resuscitation (CPR) instructions can be given after dispatch of an emergency vehicle.

Age Factors↗
PubMed1985

Evoked cortical potential correlates of rearing environment in rats.

Evoked cortical potentials were recorded from rats reared in either a complex sensory environment or in isolation. Potentials from enriched animals showed a decrease in amplitude with repeated somatic stimuli, whereas those from isolated animals did not. One hour after this experiment both groups showed similar decreases in potential amplitude with repeated stimulus. The results are interpreted as an habituation process whose development is influenced by early environment.

Animals↗
PubMed1983

Protoporphyrinogen oxidase and ferrochelatase in porphyria variegata.

Protoporphyrinogen oxidase activity and ferrochelatase activity were measured in leucocytes from patients with porphyria variegata. The mean activity of protoporphyrinogen oxidase (PPO) in porphyria variegata (PV) was about 50% of normal (P less than 0.05). The mean activity of ferrochelatase with 59Fe2+ sulphate and protoporphyrin as substrates (in the presence of ascorbic acid) was reduced by 40% (P less than 0.009). The mean activity of ferrochelatase with 59Fe3+ chloride and protoporphyrin as substrates (in the presence of reduced glutathione) was increased by 65% (P less than 0.005). Both are statistically highly significant. The findings are interpreted as follows: (a) The occurrence of a low level of protoporphyrinogen oxidase in PV is confirmed. (b) The findings indicate a concurrent structural change in ferrochelatase (this may be structurally related to (a) but no evidence of this is at present available).

Adult↗