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Biomedical subjects

C Lawson

Publications and source records attributed to C Lawson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Improved sternal fixation in the transsternal bilateral thoracotomy incision.

The success of bilateral sequential single-lung transplantation has led to the rebirth of the transsternal bilateral thoracotomy incision. Despite the multiple advantages of this incision over a median sternotomy for this operation, one distinct disadvantage is the high prevalence of sternal disruption at the transverse sternotomy site, which is traditionally closed with sternal wires. This disruption rate is between 20% and 40% in most institutions and can lead to significant pain and deformity in addition to slowing the postoperative recovery and increasing the risk of sternal infection. To overcome this problem we have designed and manufactured a device that provides a sound method of fixating the sternum. The device is composed of two plates, one anterior and one posterior to the sternum, that are fixed to each other and to the sternum by means of screws into internally threaded posts positioned in predrilled holes through the bone on either side of the sternotomy. All components of the device are made from titanium and a range of post lengths are available to accommodate variability in sternal thickness. The structure of the device is demonstrated. The device has now been inserted into a total of 20 patients after bilateral lung transplantation and the preliminary results suggest this is a superior technique for closure of a transverse sternotomy and support continued and routine use.

Bone Wires↗
PubMed1995

Hypoxia and modification of the endothelium: implications for regulation of vascular homeostatic properties.

Hypoxia is a common denominator of ischemic microenvironments. Endothelium subjected to oxygen deprivation maintains cell viability and basic biosynthetic mechanisms, but displays multiple changes in properties relevant to vascular homeostasis, including suppression of the anticoagulant cofactor thrombomodulin, decreased barrier function, and generation of proinflammatory cytokines. Diminished intracellular cAMP during the period of hypoxia and lowered nitric oxide/cGMP in the subsequent reperfusion period are proposed as fundamental mechanisms driving vascular dysfunction impacting on coagulation, permeability, vasomotor tone and leukocyte adhesivity. The period of organ preservation for transplantation, recognized to be associated with hypoxia, primes mechanisms leading to subsequent vascular dysfunction which can be ameliorated by buttressing cAMP and nitric oxide/cGMP intra- and intercellular second messenger systems. A mechanism likely to contribute to hypoxia-mediated generation of cytokines, such as interleukin 6, is activation of the transcription factor NF-IL-6, which occurs in oxygen deprivation. These data indicate that study of cellular mechanisms of endothelial perturbation in hypoxia is likely to provide insights ultimately applicable to ischemia-induced vascular damage.

Animals↗
PubMed1993

Patient advocacy: psychiatrists' perspectives.

This paper describes the responses of senior psychiatrists in Wales to a questionnaire exploring their knowledge and beliefs about patient advocacy. The results suggest mainly pro-advocacy attitudes; respondents who had not met advocacy groups involving their own patients holding attitudes almost as positive as those who had. However, despite these findings, further research is required to define the specific benefits of advocacy before further resources are diverted to the development of such services.

Attitude of Health Personnel↗
PubMed1992

Longitudinal study of gall stone prevalence at necropsy.

A prospective study of the prevalence of gall stone disease at necropsy in a stable population has been undertaken over a 10 year period up to June 1988. In women, the prevalence of gall stone disease remained static but in men aged 50-59 years it rose from 7% (n = 148) in the first three years to 18% (n = 138) in the last three years (p less than 0.01) and in men aged 60-69 it rose from 12% (n = 370) to 20% (n = 366, p less than 0.01). In the latter age group the female: male ratio fell from 2:1 to 0.8:1. The proportion of deaths from coronary heart disease in men fell slightly in those over 70 during the study period. There was a fall in deaths from coronary heart disease in all age groups in women. Men with gall stones were less likely to have had a cholecystectomy than women, and overall 88% of gall stones remained in situ. In a parallel clinical study, the number of cholecystectomies carried out in the same district fell by 18% over the 10 years without any apparent change in the provision of resources. Cholecystectomy remained almost three times more frequent in women. National data indicate that there have been major changes in the average diet before and during the period of study in favour of reducing coronary heart disease. There has been no change in mortality from coronary heart disease in young men but if the observed increase in the prevalence of gall stones in men and the decrease in deaths from coronary heart disease in women are real phenomena, it seems likely that they are diet related.

Age Factors↗
PubMed1992

Panic attacks. A neurochemical overview of models and mechanisms.

The delineation of panic disorder as a distinct diagnostic entity has provided renewed impetus for research into panic. This review describes and examines the range of neurobiological theories of panic attacks. It illustrates the diversity of mechanisms that have been invoked to explain the production of panic attacks, and which have influenced much of the current thinking about the neurochemistry of anxiety.

Bicarbonates↗
PubMed1992

Induction of autoantibodies to human enzymes following viral infection: a biologically relevant hypothesis.

Macro enzymes, i.e. complexes of normal (iso-)enzymes with an immunoglobulin, may be due to immunological cross-reactions evoked by specific viral antigenic determinants that are homologous to regions in the target enzymes. A search of the National Biomedical Research Foundation protein databank with the amino-acid sequence of human pancreatic amylase revealed a marked homology with a fragment of the yellow fever virus major envelope protein E: i.e. an overall identity of 19.7 per cent and a high degree (40.9 per cent) of conservative amino-acid substitutions over 119 amino acids. At each identical position, the corresponding residue of Taka amylase A was examined by three-dimensional structure analysis, to determine whether the position is likely to be buried or exposed. The existence of a site (epitope) on amylase recognized by an anti-amylase antibody is discussed.

Amino Acid Sequence↗
PubMed1990

Flumazenil provocation of panic attacks. Evidence for altered benzodiazepine receptor sensitivity in panic disorder.

The possibility that panic disorder might be due to abnormal activity of endogenous ligands of the benzodiazepine receptor was investigated with the use of the benzodiazepine antagonist flumazenil. Physiological and subjective psychological responses to this selective antagonist were measured in 10 patients with panic disorder and in 10 control subjects, by using a placebo-controlled crossover study design. Subjective anxiety responses after flumazenil infusion were significantly higher in the patient group with panic disorder than in the controls, and eight patients with panic disorder but no controls had panic attacks. This anxiogenic effect of flumazenil in the patients argues against the presence of endogenous anxiogenic (inverse agonist) ligands. Possible explanations include the differential production of an anxiolytic endogenous ligand or an altered benzodiazepine receptor "set-point." Such an abnormality may contribute to the pathogenesis of panic disorder.

Adolescent↗
PubMed1990

The neurochemistry of anxiety: an update.

1. Recent neurochemical investigations have enhanced our understanding of the anxiety disorders. Emphasis has been placed on dysfunction in central benzodiazepine, serotonergic and noradrenergic systems. 2. Changes in activity of endogenous ligands for the benzodiazepine receptor or in benzodiazepine receptor sensitivity appear to modulate anxiety. 3. There is evidence of serotonergic involvement in anxiety, in that serotonin agonists may increase anxiety, whilst drugs that reduce serotonin function are anxiolytic. 4. Noradrenergic dysfunction, especially that of alpha-2-adrenoceptors, provides the strongest etiological evidence in the development of anxiety. 5. A number of testable hypotheses can be generated from our present knowledge. As a result, new and more specific treatments may become apparent for the anxiety disorders.

Anxiety↗
PubMed1990

Engineering resistance to mixed virus infection in a commercial potato cultivar: resistance to potato virus X and potato virus Y in transgenic Russet Burbank.

Potato virus X (PVX) and potato virus Y (PVY) infection in potato may result in the loss of certification of seed potatoes and affect quality and yield of potatoes in commercial production. We transformed a major commercial cultivar of potato, Russet Burbank, with the coat protein genes of PVX and PVY. Transgenic plants that expressed both CP genes were resistant to infection by PVX and PVY by mechanical inoculation. One line was also resistant when PVY was inoculated with viruliferous green peach aphids. These experiments demonstrate that CP protection is effective against mixed infection by two different viruses and against mechanical and aphid transmission of PVY.

Amino Acid Sequence↗
PubMed1990

Parents' perceptions of their child's acute pain experience.

Painful procedures, experienced by many pediatric patients early in their admission, have been identified by parents in our clinical practice as a source of stress. The purpose of this study was to examine parents' perceptions and concerns about their child's acute pain experience. A convenience sample of 71 parents of 62 children was given a questionnaire that focused on the child's pain intensity, the behaviors that indicated the child was in pain, and the parents' preparation for and involvement in the child's pain experience. The majority of parents were asking for more information about and greater participation in procedures that caused their child pain.

Adult↗
PubMed1989

Octanoic acid inhibits astrocyte volume control: implications for cerebral edema in Reye's syndrome.

Octanoic acid has been implicated in the pathogenesis of cytotoxic cerebral edema in Reye's syndrome. Using astrocytes from primary culture, we studied the dose-dependent effects of octanoate on cellular volume regulation and metabolism. Astrocyte volume recovery following hypoosmotic swelling was stimulated by 1.0 mM octanoate and inhibited by 3.0 mM octanoate. Parallel effects were obtained at these concentrations on the activity of the Na+,K+-dependent ATPase. Cellular ATP concentrations also were reduced 36% with the higher octanoate concentration. These effects of octanoate may contribute to the severe astrocyte swelling observed in the brains of Reye's syndrome patients.

Adenosine Triphosphate↗
PubMed1986

Tremors in Samoyed pups with oligodendrocyte deficiencies and hypomyelination.

Over a 3-year period a breeder of Samoyed dogs observed six litters in which one or more pups at 3 weeks of age showed generalized tremors and an inability to stand. One affected pup, a 5-week-old male, was referred for clinical and pathological evaluation. Gross and microscopic studies including immunocytochemical demonstration of myelin basic protein, revealed a lack of myelin throughout the central nervous system. Ultrastructural studies revealed that a total absence of normal myelin was associated with oligodendroglial deficiencies. Oligodendrocytes were immature in appearance, greatly reduced in number, and incapable of forming compact myelin. Astrocytosis and an increase in the third type of neuroglial cells were observed. The changes differed from those reported in other canine forms of hypomyelinogenesis and were compared with hypomyelinating diseases in other species. The findings suggested that this hypomyelination was the result of retarded gliogenesis.

Animals↗