PubMed Health⌕ Search

Biomedical subjects

C A Cox

Publications and source records attributed to C A Cox.

At least 19 recordsLinked to original sources
PubMed1998

Fusion of green fluorescent protein with the Zeocin-resistance marker allows visual screening and drug selection of transfected eukaryotic cells.

Green fluorescent protein (GFP) and the Zeocin-resistance gene Sh ble (ZeoR) were fused together to generate a bifunctional protein for the identification and selection of transfected mammalian cells. Expression of this hybrid selectable marker, GFP-ZeoR, was visually detected and conferred Zeocin resistance in prokaryotes and eukaryotes. This selectable marker provides a way to determine transient transfection efficiencies in tissue culture cells using fluorescence microscopy. Expression of the GFP-ZeoR was also used to identify and select stable mammalian cell lines expressing a heterologous gene. Selection was efficient and GFP fluorescence provides an excellent, noninvasive technique to monitor the success of Zeocin selection during the development of the stable cell lines. This hybrid resistance gene combines the functional properties of the Zeocin-resistance marker and GFP and should be useful for combined selection and fluorescence in a variety of organisms.

Animals↗
PubMed1997

Comparison of perfluorochemical fluids used for liquid ventilation: effect of endotracheal tube flow resistance.

Neonatal endotracheal tubes with small inner diameters are associated with increased resistance regardless of the medium used for assisted ventilation. During liquid ventilation (LV) reduced interfacial tension and pressure drop along the airways result in lower alveolar inflation pressure compared with gas ventilation (GV). This is possible by optimizing liquid ventilation strategies to overcome the resistive forces associated with liquid density (rho) and viscosity (mu) of these fluids. Knowledge of the effect of rho, mu, and endotracheal tube (ETT) size on resistance is essential to optimize LV strategies. To evaluate these physical properties, three perfluorochemical (PFC) fluids with a range of kinematic viscosities (FC-75 = 0.82, LiquiVent = 1.10, APF-140 = 2.90) and four different neonatal ETT tubes (Mallincrokdt Hi-Lo Jet ID 2.5, 3.0, 3.5, and 4.0 mm) were studied. Under steady-state flow, flow and pressure drop across the ETTs were measured simultaneously. Resistance was calculated by dividing pressure drop by flow, and both pressure-flow and resistance-flow relationships were plotted. Also, pressure drop and resistance were each plotted as a function of kinematic viscosity at flows of 0.01 L.s-1 for all four ETT sizes. Data demonstrated a quadratic relationship with respect to pressure drop versus flow, and a linear relationship with resistance versus flow: both were significantly correlated (R = 0.92; P < 0.01) and were inversely related to ETT size. Additionally, there was a significant correlation between pressure drop or resistance and kinematic viscosity (R = 0.99; P < 0.01). For LV in neonates these data can be used to select the optimum ETT size and PFC liquid depending OR the chosen ventilation strategy.

Airway Resistance↗
PubMed1996

Persistent neuropsychological deficits following whiplash: evidence for chronic mild traumatic brain injury?

OBJECTIVE: To investigate claims of neuropsychological evidence for acquired brain damage (axonal degeneration) in chronic whiplash. DESIGN: Fifteen whiplash patients (Whiplash) were compared with 10 patients who had documented moderate-to-severe head injury (Mod-Sev), and with 24 patients who had chronic pain syndrome (CPS) and no history of head injury on two tests of mental efficiency considered highly sensitive to and specific for the subtle effects of brain trauma. All 3 groups, assessed 4 years after onset in a teaching hospital setting were matched for age, education, and IQ. Exclusion criteria included narcotics/benzo-diazepines or (suspected) malingering. Subjective ratings of depression and pain were collected as well as objective indices of outcome (return to work/school). MEASURES: Neuropsychological test scores were subjected to ANOVA followed by regression analysis regarding the possible effects of age, IQ, pain, and mood ratings. RESULTS: No differences between the Whiplash, Mod-Sev, or CPS groups on the neuropsychological tests emerged. IQ was strongly related to mental efficiency. Counterintuitively, Mod-Sev patients complained of less depression and pain than did Whiplash or CPS patients (where no differences were seen) and displayed a better outcome. Finally, although results from 3 of the original 18 patients in the Whiplash group were later discarded for malingering, no malingering was detected in the 2 other groups. CONCLUSIONS: The theory of neuronal degeneration in the etiology of whiplash-related cognitive complaints was not supported, nor was the specificity of neuropsychological tests in detecting the subtle effects of brain trauma.

Adult↗
PubMed1996

Liquid ventilation: a comprehensive overview.

Despite advances in neonatology, some infants do not respond to current pharmacologic and ventilatory techniques. Others suffer chronic lung disease, require prolonged ventilatory support, and experience significant morbidity during infancy due to the elevated inflation pressures used to treat their respiratory problems. Over the past 30 years, results of studies in premature animals as well as clinical trials have demonstrated that ventilation with oxygenated perfluorochemical (PFC) fluids provides effective gas exchange and improved lung mechanics. PFC fluids are biologically inert, have a high gas solubility and a low surface tension, and are nonbiotransformable. With liquid ventilation, alveolar pressures are low because the high surface tension of the gas-lung interface in eliminated. Potential neonatal applications include surfactant deficiency, persistent pulmonary hypertension, meconium aspiration, diaphragmatic hernia, pneumonia, and a vehicle for drug delivery. In order to develop a nursing care plan for the liquid-ventilated infant, nurses need knowledge of the physiologic changes involved in liquid ventilation, as well as its mechanics.

Fluorocarbons↗
PubMed1995

A cross-sectional survey of condom use in conjunction with other contraceptive methods.

A cross-sectional survey of 3,136 women attending family planning clinics in Texas was conducted to examine past use of and future plans for use of condoms by partners during sexual intercourse for disease prevention in conjunction with other contraceptive methods. Following the receipt of clinical services, including counseling about family planning and disease prevention, both contraceptive and planned condom use reporting increased for the majority of subjects. However 22% of the sample indicated that they intended to reduce condom use in the future and instead use a contraceptive which protects from pregnancy but not from disease. Condom use was indicated more frequently for those who reported at least one risk factor for HIV, but 17% of those at risk indicated lower future condom use than past use. This suggests that without changes in risk behavior, these women will be at increased risk of HIV or another sexually transmitted disease.

Adolescent↗
PubMed1993

One-year experience with subdermal contraceptive implants in the United States.

Women who received Norplant contraceptive implants from any of fifteen clinical settings in southeast Texas, U.S.A., were followed for one year to determine their reactions to the method. Of 1,385 who enrolled to receive Norplant implants, 1,253 had implants inserted. Side effects were reported by 78% of those receiving implants and 70% described changes in bleeding patterns. Spotting or irregular bleeding, weight gain and headaches were the conditions reported most frequently. Nine pregnancies were reported during the study period. Six of these, however, existed before the implants were inserted. At the one year anniversary, 143 of women receiving implants had had them removed. Those who discontinued method use were less satisfied, reported more side effects and were more likely to have planned to have another child, thus using the method for spacing, or to have had a change in their marital status while they were using the contraceptive. Providers should counsel patients to focus attention on plans for the future in selecting their contraceptive method. In addition, we recommend, as does the product's distributor, that providers confirm that patients are not pregnant prior to inserting implants.

Adolescent↗
PubMed1992

External beam radiotherapy for incidental adenocarcinoma of the prostate discovered at transurethral resection.

This paper updates the results of 89 patients treated between 1967 and 1989 for incidental carcinoma discovered at transurethral resection of the prostate (Stanford stage T0 or AJC-UICC stage T1) with external beam irradiation. Twenty-two patients had Stanford T0 focal (less than 5% involvement of the prostatic chips) and 67 presented with Stanford T0 diffuse (5% or more involvement). Follow-up ranges from 4 months to 25.1 years, with a mean follow-up of 9.8 years. The actuarial local control for Stanford T0 focal is 100%, and 70% for Stanford T0 diffuse at 15 years. There was no difference in survival between Stanford T0 diffuse and T0 focal and the expected survival of an age-matched control population. Patients who were treated when younger than 65 had a similar local control and distant relapse when compared to those treated when 65 or older. There was no difference in local control, freedom from relapse, or disease-specific survival when the 38 patients who received irradiation to the prostate only are compared with the 29 who also received pelvic irradiation for Stanford T0 diffuse carcinoma. Patients with a Gleason score of 6 or more, when compared with those with a score of 5 or less, experienced more distant relapses and similar local control, suggesting that patients with a high grade tumor have occult metastases at presentation.

Adenocarcinoma↗
PubMed1990

Composite (adenocarcinoid) tumors of the gastrointestinal tract.

Tumors of the gut with composite features of both adenocarcinoma and carcinoid have been recognized mainly in the appendix. There also have been isolated reports of similar tumors arising from other parts of the gastrointestinal tract. It is generally concluded that these tumors have better prognosis than adenocarcinomas of the gastrointestinal tract. We reported six patients with composite tumors arising from the stomach in one, small intestine in two, cecum in two, and rectum in one patient. Clinical presentations in each was suggestive of malignancy with extension to either serosa and/or lymph nodes. Metastasis to liver was present in two patients. Histologically, the tumor showed glands with surface microvilli resembling adenocarcinoma and also organoid pattern with neurosecretory granules in cells resembling carcinoid. Two patients died three and nine months after surgery. The clinical presentation, findings at operation, and the postsurgical course of these six patients reveal that these tumors behave more like an adenocarcinoma than carcinoid and do not appear to have a better prognosis than ordinary adenocarcinoma.

Adenocarcinoma↗
PubMed1990

Effects of lithotripter fields on development of chick embryos.

Chick embryos at 72 h incubation were subjected to three double shock waves from a Wolf Model 2137.50 Electrohydraulic Lithotripter. The pressure amplitude at the embryo was adjusted by variation of the distance from the source to the embryo. After a total of 120 h of incubation, they were assessed for developmental abnormalities. Early deaths, delayed deaths and malformations were all significantly increased at pressures of 10 MPa with suggestions of possible effects at lower pressure levels.

Animals↗
PubMed1990

Test for kidney hemorrhage following exposure to intense, pulsed ultrasound.

A recent study has found that the threshold for extravasation in mouse kidney tissues by exposure to a spark-generated shock wave is of the order of 3-5 MPa (peak positive pressure). Since the mode pressure used by commercial pulsed Doppler ultrasound units is approximately 5 MPa, it is essential to determine whether these observations are relevant to diagnostic ultrasound. Hence, a comparable study has been completed using the same pathological endpoints but with exposure to pulsed ultrasound (10 microseconds pulse length) at 1.2 MHz and 3.8 MHz in which peak positive pressures exceeded 10 MPa. At these levels the focal waves are in shock because of the nonlinear properties of the propagating medium. The results of the pulsed ultrasound study were negative. Although this finding is encouraging for the use of diagnostic ultrasound, the two studies eventually must be integrated into a single mechanistic picture before the limits of safety will be known.

Animals↗
PubMed1989

Inhibitors of arachidonic acid lipoxygenase impair the stimulation of inositol phospholipid hydrolysis by the T lymphocyte mitogen phytohaemagglutinin.

Piriprost and nordihydroguiaretic acid (NDGA), specific inhibitors of arachidonate lipoxygenase, inhibited phytohaemagglutinin (PHA)-stimulated breakdown of inositol lipids in human T lymphocytes. The dual inhibitors eicosatetraynoic acid (ETYA) and BW 755C, which inhibit both lipoxygenase and cyclooxygenase, also had similar actions, whereas indomethacin and acetylsalicyclic acid, which inhibit cyclooxygenase alone, did not. The effects of lipoxygenase inhibitors and dual inhibitors were reversible. These agents did not inhibit phosphatidylinositol-4,5-bisphosphate-specific phospholipase C (PIP2-PLC) in vitro. Bromophenacyl bromide, and irreversible inhibitor of phospholipase A2, also abolished PHA-stimulated inositol lipid breakdown without affecting PIP2-PLC in vitro. The results are consistent with a role for the PHA-stimulated generation of arachidonic acid and its conversion to lipoxygenase metabolites (e.g. leukotrienes and/or hydroxyeicosatetraenoic acids) as intermediate steps in the signal transduction pathway between cell-surface mitogen receptors and the stimulation of PIP2-PLC in lymphocytes.

Arachidonate Lipoxygenases↗
PubMed1988

Hyaluronate accumulation and nerve-dependent growth during regeneration of larval Ambystoma limbs.

Hyaluronate-mediated expansion of the extracellular matrix has been suggested as an important element of growth and morphogenesis in several developing systems. In vitro, various growth factors have been shown to stimulate hyaluronate synthesis as well as cell proliferation. A similar link between proliferation and hyaluronate production during in vivo growth is difficult to demonstrate, because in most systems the source of growth-promoting factors is either not known or not amenable to experimental manipulation. During amphibian limb regeneration, cell proliferation depends upon paracrine release of factors from axons in the limb stump, and the nerve supply can be eliminated or augmented experimentally for study of growth in this system. Denervated and amputated limbs of larval salamanders do not begin to regenerate until distal areas of the limb stumps are reinnervated. We have used such limbs to examine the effect exerted by the reappearance of nerves on the amount of hyaluronate in the tissue undergoing the growth response. Hyaluronate was demonstrated by the metachromatic dye Ethyl Stains-all, which stains hyaluronate blue while sulfated glycosaminoglycans (GAGs) and proteins in the extracellular matrix stain various shades of violet, and by microspectrophotometry of alcian-blue-stained GAGs in serial sections pretreated with buffer or with Streptomyces hyaluronidase (SH) to remove hyaluronate specifically. Both methods showed little hyaluronate in the distal region of limb stumps prior to reinnervation, while reinnervated stumps had amounts of hyaluronate similar to those of control blastemas. Autoradiography of 3H-glucosamine-labeled limbs indicated that hyaluronate in the blastemas of reinnervated limb stumps included material newly synthesized by cells throughout the growing tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambystoma↗
PubMed1987

Influence of a calcium dependent protease inhibitor on platelet activation and secretion.

Continuous proteolysis resulting in consumption of major cytoskeletal proteins may be essential for platelet activation and aggregation. In this study we evaluated the effect of a known protease inhibitor, Leupeptin, on agonist induced platelet aggregation and secretion. Platelets exposed to 10 ugs/ml of Leupeptin did not aggregate in response to the action of thrombin (0.2 u/ml). However, a concentration of Leupeptin as high as 250 ugs/ml did not prevent arachidonate induced aggregation and secretion. Leupeptin (100 ugs/ml) effectively blocked thrombin (0.2 u/ml) induced elevation of cytosolic calcium, but did not affect arachidonate induced elevation of platelet intracellular calcium levels. At a concentration of 100 ug/ml, Leupeptin effectively blocked thrombin (0.5 u/ml) induced clot formation of platelet poor plasma, suggesting that it can exert its effect on thrombin by preventing fibrinogen degradation. Effective Ki for the competitive inhibition of thrombin induced hydrolysis of a chromogenic substrate, S2238, by Leupeptin was 2.4 uM. Leupeptin inhibition of platelet function was reversible by washing platelets free of the polypeptide. Results of our study demonstrate that Leupeptin inhibits thrombin induced platelet activation, probably by interfering with its proteolytic activity on the platelet surface membrane. However, inhibition of platelet surface membrane associated proteases did not prevent activation of platelets by other agonists.

Blood Coagulation↗
PubMed1979

Who cares? Nursing and sociology: the development of a symbiotic relationship.

The paper has three aims: to illustrate ways in which sociology may help nurses to achieve their primary objective: good patient care; to show how nursing can contribute to sociology; and to indicate some conditions for a healthy relationship between the two activities. After a brief discussion of the nature of sociology, intended for non-sociologists, four examples of ways in which sociology may be relevant to nursing are discussed: (i) Implications for nursing of changing patterns of disease, dependency and death; (ii) Social and cultural variations in perceptions of, and responses to, pain and disease; (iii) Organizational analyses, with particular reference to the importance of nurse-patient communication; (iv) Sociological studies of inter-personal relationships, illustrated by a study of student nurse training. Nursing is described as the major caring profession; as such it has inherent interest for sociologists interested in health care. However, its sociological interest is enhanced by the fact that it is permeated by paradoxes. Reference is also made to current debate on the most appropriate model for health care: the traditional medical model places relatively greater emphasis on cure than does nursing, with its relatively greater involvement with care. It is suggested that current patterns of disease and dependency increase the importance of the care model, and that nursing could play a crucial role in such a shift of emphasis. Having shown that sociology can make positive contributions to nursing, attention is drawn to certain dangers. Nursing should thus make sure that the sociology which it welcomes into its domain is academically sound, and not ideology in disguise. It is also suggested that nursing education should encourage more critical thinking, to enliven nurses' appreciation of what sociology has to offer, and to improve their ability to evaluate the quality of health care.

Culture↗
PubMed1977

Aspects of the six-month developmental examination in a longitudinal study.

In a longitudinal study concerned with the early detection of delayed and aberrant development, the findings at the six-month examination have been studied in some detail. All births within a given catchment area were included and the results on 1200 babies seen at this age are reported. The findings illustrated that under ordinary clinic conditions not all children achieved the "milestones" expected of them at a particular age. The examinations were carried out in child health clinics by a heterogeneous group of doctors with widely varying training and experience, and this is reflected in the differences between the findings of the more and the less experienced doctors. The problems of follow-up and their implications for total population surveillance programmes are considered. A positive approach to routine developmental examinations is advocated, with the emphasis not only on early detection of developmental problems but also on enabling all children to achieve their optimum potential.

Child Development↗
PubMed1976

Child health clincs and inverse care laws: evidence from longitudinal study of 1878 pre-school children.

In a longitudinal study it was intended that 1878 children should receive periodic developmental examinations from the age of 6 weeks to 3 years. The children were divided into those with a high or low risk of developmental problems. Although clinic attendance rate of 85-89% were achieved in the catchment area 100% coverage was difficult because of population mobility and non-attendance at clinics. Children in families who moved away from the area were more difficult to trace and thus more likely to miss developmental examinations. This was a greater problem in the high-risk group. Altogether 683 home developmental examinations were carried out on 269 children who did not attend clinics. Thirty-five per cent of these children were in the high-risk group compared with 22% in the study population, and significantly more had developmental problems. Thus one possible way of reaching and helping such children is though home developmental examinations.

Child Development↗