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Biomedical subjects

K Stevens

Publications and source records attributed to K Stevens.

At least 109 records · Page 6Linked to original sources
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Effects of pregnancy and delivery on serum prolyl endopeptidase (PEP) activity: alterations in serum PEP are related to increased anxiety in the early puerperium and to postpartum depression.

BACKGROUND: There is now some evidence that anxiety or anxiety disorders are related to increased activity of serum prolyl endopeptidase (PEP) and that major depression is related to lower serum PEP. The aims of the present study were to examine (i) the effects of pregnancy and delivery on serum PEP and (ii) the relationships between serum PEP and postpartum depression, anxiety in the early puerperium and a past history of depression. METHODS: Serum PEP activity was measured in 11 healthy nonpregnant and in 98 pregnant women 3 days before delivery and 1 and 3 days after delivery. On the same occasions, pregnant females completed the Spielberger State Anxiety Inventory (STAI) and were divided into high and low anxiety responders, as defined by changes in the STAI. The presence of a previous depression and postpartum depression within 3 months of delivery was assessed by means of DSM-IV criteria. RESULTS: Serum PEP activity was significantly higher 1 and 3 days after delivery than before. Women with a past history of depression as well as anxiety responders had significantly increased serum PEP activity over nonpregnant women and puerperae with a negative history and anxiety nonresponders, respectively. Parturients who developed a postpartum major, but not minor, depression had significantly lower serum PEP than parturients without postpartum depression. The results were controlled for maternal and labor variables, such as type of analgesia and delivery, induction of labor, breast feeding, parity, and duration of pregnancy and labor. CONCLUSIONS: Our results show that, in puerperae, increased serum PEP is related to increased state anxiety in the early puerperium and that lowered serum PEP is related to a subsequent postpartum major depression. INTERPRETATION: The results suggest that increased serum PEP may be related to postpartum anxious blues and that lowered serum PEP may predispose toward postpartum major depression.

Adult↗
PubMedDate not supplied

Mind control.

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Periodicals as Topic↗
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Blood platelets of the African elephant.

Platelet counts of 22 elephants varied between 229 x 10(9) and 622 x 10(9)/L. Light microscopy showed the platelets to be small, while electron microscopy revealed well preserved but activated platelets with some morphological differences from other mammalian platelets. Dense bodies, alpha-granules, glycogen and mitochondria were present in most sections. Microtubules and the surface connecting canalicular system appeared to be absent, but numerous filamentous structures and Golgi bodies were observed.

Africa↗
PubMedDate not supplied

Initial experience with the AbioCor implantable replacement heart at the University of Louisville.

Potential benefits of heart transplantation are limited by the severe donor organ shortage. The AbioCor implantable replacement heart has been developed as a potential alternative to heart transplantation. We report our initial experience with the AbioCor in a bovine model. A right thoracotomy was performed for access to the heart and great vessels. After initiation of cardiopulmonary bypass, excision of the native ventricles was followed by orthotopic placement of the IRH and complete implantation of the transcutaneous energy transfer coil, controller, and battery pack. Invasive monitoring of IVC, SVC, carotid artery, pulmonary artery, and left atrial (LA) pressures was performed in all animals. Twelve calves have undergone implantation of the AbioCor. There were three early deaths, one from bleeding, one from respiratory failure, and one from neurodysfunction from low flow during CPB. Nine animals have had a normal recovery and survived a mean of 24.5 days (range, 4-48 days). All the animals have demonstrated excellent hemodynamics with the maintenance of normal pressures in the LA, SVC, IVC, pulmonary artery, and aorta. Adjustment of the right-sided internal hydraulic fluid shunt has allowed for control of right-left balance and, thereby, manipulation of left and right side filling pressures. Late morbidity has consisted of neck wound infection and sepsis, pneumonia, and bleeding. Successful orthotopic implantation of all components of the AbioCor has been achieved in a bovine model. This device has demonstrated restoration of normal hemodynamics and excellent function of the atrial hydraulic shunt to achieve right-left balance.

Animals↗
PubMedDate not supplied

Blood lactic acid levels after artificial heart implantation.

The aim of this study is to investigate blood lactic acid levels after the placement of the AbioCor implantable replacement heart to determine whether circulatory support with the AbioCor device results in adequate tissue perfusion. Tissue perfusion may not be adequate during cardiac surgery, especially with the use of cardiopulmonary bypass (CPB). Inadequate perfusion is usually associated with anaerobic metabolism, metabolic acidosis, and lactate accumulation. Ten calves had implantation of the AbioCor by means of a right thoracotomy. Standard cardiopulmonary bypass was performed during surgery. Lactic acid levels and blood gas analyses were measured. All animals were monitored for pressures in the aorta, pulmonary artery, and left and right atria. The output of the AbioCor was calculated based on beat rate and stroke volume. All animals were rapidly weaned off cardiopulmonary bypass to full AbioCor support and had normal hemodynamics with normal filling pressures. The lactic acid levels were elevated after surgery, peaked at 8 to 12 hours, and then gradually decreased to the normal range 24 hours after surgery. There was a positive relationship between lactate levels, oxygen consumption, and extraction rate, that is, the lactic acid levels were higher in the presence of increased oxygen consumption and increased oxygen extraction rate. There was a negative relationship between lactate levels and oxygen delivery, and arterial and venous oxygen content, that is, the lactic acid levels were higher when oxygen delivery and arterial and venous oxygen contents were low. The pathophysiology of lactic acidosis is uncertain, but is most likely due to inadequate perfusion during cardiopulmonary bypass, and lactate washout after adequate perfusion has been established. The return to aerobic metabolism with clearance of lactate demonstrates that the AbioCor is able to provide complete circulatory support with normal tissue perfusion.

Acidosis, Lactic↗
PubMedDate not supplied

Recombinant human erythropoietin in the treatment of cancer-related anaemia.

The aim of this study was to investigate the effects of recombinant human erythropoietin (rh-EPO) in patients with cancer-related anaemia. Thirty-six ambulatory patients who had malignant neoplasms and haemoglobin (Hb) values of < 11 g/dl (Pretoria is 1,310 m above sea level) entered the study. Patients with renal insufficiency or anaemia caused by bleeding or haemolysis, and patients with iron deficiency or megaloblastic anaemia, were not entered in the study. 22 IU/kg rh-EPO was given subcutaneously 3 times/week. The dose was escalated if Hb values did not rise after 4 weeks. All 36 patients were evaluable for toxicity. Side effects ascribed to rh-EPO were pain or discomfort at the site of injection (12 patients), heart palpitations (3 patients), skin rash (2 patients) and hypertension, deep vein thrombosis, and myalgia in 1 patient each. Thirty of the 36 patients who entered the study were evaluable for response. There were 16 females and 14 males among the evaluable patients. Median age was 64.5 years. Response, defined as an increase of Hb of at least 2 g/dl or to 12.5 g/dl, for at least 1 month, was documented in 12 patients. This was accompanied by an improvement in performance status and occurred within 1 month in 5 of the 12 patients who responded. rh-EPO has a limited but measurable therapeutic value for patients with cancer-associated anaemia.

Adult↗
PubMedDate not supplied

Formulating priorities for research in nursing education: a consensus-building approach.

To expand the scientific foundation for nursing education, the National League for Nursing is establishing a national agenda for research in nursing education. This groundbreaking effort will define research priorities that can serve as a rallying point for education researchers across the nation. The goal of this consensus-building effort is to focus nursing education research efforts on discovering the core of knowledge needed to bridge education and practice as we move into the 21st century. This article describes the process being used in this historic dialogue.

Decision Making↗