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Biomedical subjects

A Allen

Publications and source records attributed to A Allen.

At least 217 records · Page 12Linked to original sources
PubMed1990

Notes from the annual meeting of the American Society of Anesthesiologists.

Several important developments were reported at the 1989 Annual Meeting of the American Society of Anesthesiologists: (1) a computerized machine called HealthQuiz asks patients health questions, and in less than 10 minutes provides a printout of answers, a summary of symptoms, and a list of suggested laboratory tests; (2) a simple device provides continuous measurements of a critically ill patient's oxygen and carbon dioxide levels; (3) near-infrared reflectance is a new technique that may provide the first accurate real-time measurement of critical oxygen levels in the brain; (4) pulse oximeters may provide false readings in patients who smoke cigarettes; (5) a new test may accurately predict the survival chances of a child in a coma; (6) the fastest growing subspecialty in anesthesiology is chronic pain management clinics; (7) alpha-2 adrenergic agonists improve pain relief without the unwanted side effects of narcotics; (8) clonidine appears to suppress the dangerous shivering that often occurs in postanesthesia patients; (9) flumazenil was successfully tested as an agent to reverse the drowsiness caused by midazolam; and (10) ephedrine minimizes nausea and vomiting in patients undergoing ambulatory surgery.

Anesthesiology↗
PubMed1990

Environmental safety: an essential element of quality care.

Quality care results when nurses conform to standards of practice. Health care providers are accountable for compliance with laws that set standards for environmental safety, standards set by accrediting bodies, state practice acts, and community and institutional standards. Conformance with standards requires continuous monitoring, updating of information, and staff education. The PACU is a busy place with rapid changes in patient census, patient status, and staffing needs. It may seem difficult to allot time for safety education and practice sessions. The authors offer suggestions, using fire safety as an example, for providing a safe environment for patients and personnel in the PACU.

Accident Prevention↗
PubMed1990

TriCouncil for Nursing issues statement on assistive personnel for the registered nurse.

In 1987, The House of Delegates of the American Medical Association (AMA) recommended initiatives to solve the shortage of bedside caregivers. The Registered Care Technician (RCT) proposal was the result. The intent of the proposal was to create a pool of technical workers who would assist nurses. The nursing community perceived the RCT proposal as an attempt to interfere in nursing's domain, and even to undermine their struggle to create two levels of entry into nursing: associate degree and baccalaureate. Nursing organizations formed coalitions, held meetings, published position statements, and mounted campaigns to sidetrack the AMA plans. The training, supervision, and role of assistive personnel were key areas of concern. The TriCouncil for Nursing recently issued a position statement regarding the categories and functions of assistive personnel.

Allied Health Personnel↗
PubMed1989

Increased vulnerability of the mildly traumatized rat brain to cerebral ischemia: the use of controlled secondary ischemia as a research tool to identify common or different mechanisms contributing to mechanical and ischemic brain injury.

Fasted Wistar rats were subjected to either a mild mechanical injury, 6 min of transient forebrain ischemia, or a mild mechanical injury followed 1 h later by 6 min of forebrain ischemia. EEG and evoked potentials were assessed intermittently and morphological analyses were performed after 7 days postinjury survival. In all groups complete qualitative recovery of electrical activity and general behavior was observed with 7-day survival. However, rats subjected to combined concussion and ischemia displayed EEG spike activity and a delayed return of EEG and evoked potentials during acute recovery not evident in other groups. No overt neuronal cell loss was seen in trauma alone and was minimal or absent in ischemia alone. However, extensive bilateral CA1 and subicular pyramidal cell loss was found in the septal and mid-dorsal hippocampi in the combined trauma and ischemia group. In contrast, no overt axonal injury was found in any group. We conclude that even mild mechanical injury can potentiate selective ischemic hippocampal neuronal necrosis in the absence of overt axonal injury. This potentiation also occurs in conjunction with more generalized electrophysiological disturbances such as EEG evidence of postischemic neuronal hyperactivity suggesting that mild concussion may also decrease the threshold for post-ischemic neuronal excitation. These results suggest the potential of this model for examining common or different injury mechanisms in mechanical and ischemic brain injury.

Animals↗
PubMed1989

Rehabilitation after lower limb amputation: a comparative study of above-knee, through-knee and Gritti-Stokes amputations.

A study of 169 unilateral amputees under three Disablement Services Centres was performed. The study comprised 88 above-knee, 54 through-knee and 27 Gritti-Stokes amputations. Satisfactory rehabilitation occurred in 33 per cent of above-knee, 62 per cent of through-knee and 44 per cent of Gritti-Stokes patients (56 per cent overall). The better rehabilitation of through-knee versus above-knee amputees (P less than 0.02) was also found in a group of patients matched for comparable age and duration of amputation as well as in a group of age-matched vascular amputees. Through-knee amputees relied significantly less on wheelchairs than above-knee (P = 0.016) and Gritti-Stokes (P = 0.05) amputees. The prosthesis used for the through-knee and Gritti-Stokes amputations was considered unsightly in 50 per cent of cases (versus 31 per cent for the above-knee prosthesis). The superior rehabilitation with through-knee amputations should prompt us to improve both our technique for this amputation and the prostheses currently available. A through-knee amputation should be performed in preference to an above-knee amputation in the case where either is surgically possible, and a below-knee amputation not feasible.

Adult↗
PubMed1989

Acute ultrastructural response of hypoxic hypoxia with relative ischemia in the isolated brain.

The acute cortical response to surgical brain isolation and subsequent extracorporal normoxic or 30 min hypoxic (PaO2 = 20 mm Hg) perfusions (hypoxic hypoxia with relative ischemia) was evaluated. Cerebral blood flow, arterial pH and CO2 were maintained constant during both perfusions; only the arterial oxygen content was changed. The isolated brain model used in this and previous investigations produces no qualitative ultrastructural changes in the neocortex following brain isolation and normoxic perfusion. However, the acute cortical structural response to 30 min of hypoxic hypoxia with relative ischemia demonstrated a number of important observations. Hypoxic hypoxia produced ultrastructural responses common to cerebral ischemia such as nuclear chromatin clumping, nucleolar condensation and cytoskeletal breakdown. Although neuronal abnormalities seen after 30 min of hypoxic hypoxia were similar to those acute neuronal changes observed following complete cerebral ischemia without recirculation, they differed three ways: (a) mitochondrial swelling and microvacuolation were observed in many cortical pyramidal neurons. (b) Glycogen particles within astroglial processes were observed even after a 30-min period of hypoxic hypoxia. (c) Perivascular astroglial swelling was minimal despite considerable perineuronal swelling. In contrast, incomplete cerebral ischemia produces mitochondrial changes similar to those in hypoxic hypoxia but also causes the depletion of tissue glycogen and perivascular glial swelling. Thus, hypoxic hypoxia with relative ischemia produces a unique acute ultrastructural response compared to either complete or incomplete cerebral ischemia.

Animals↗
PubMed1989

The dependence of size and functional properties of pig gastric mucus on the isolation method used.

The size of isolated gastric mucin is substantially larger if proteolysis is rigorously excluded during the isolation procedure by inclusion of proteinase inhibitors with or without guanidinium chloride. Pig gastric mucin isolated in 0.2 M NaCl (without proteinase inhibitors) so25,w, 33S, Mr approximately 2 x 10(6) has consistent physical and chemical properties, retains the gel-forming properties of the native mucus secretion and is readily susceptible to proteolysis although it has undergone proteolytic "nicking" during isolation. Gastric mucins isolated in proteinase inhibitors with guanidinium chloride are of larger size so25,w, 41-110S but precipitate from solution at gel-forming concentrations. Reduction of all these gastric mucin preparations with either 0.2 M mercaptoethanol or 10 mM dithiothreitol produced subunits of size in the region of Mr approximately 5 x 10(5). Gel filtration studies also showed that reduced mucin subunits prepared from gastric mucins isolated in guanidinium chloride could reassociate to form larger subunits of size approximately Mr approximately 2 x 10(6). The dependence of gastric mucin size on the isolation procedure is discussed.

Animals↗
PubMed1989

Studies on mucus biosynthesis in the gastrointestinal tract.

Mucin biosynthesis in the rat gastrointestinal tract was measured by following the incorporation of radioactive precursors, [3H] glucosamine, [3H] galactose and [3H] serine. The radioactive mucin was isolated by a combination of equilibrium centrifugation in a CsCl density gradient and gel-filtration or, by papain digestion and removal of digested peptides by dialysis. Radioactive precursors were incorporated into mucin by stomach, duodenum and colon in vivo and by stomach in organ culture in vitro. In the latter, incorporation was approximately 20-fold greater than in vivo, over 6 h. In all cases lower molecular weight non-mucin glycoprotein, of the same buoyant density as mucin, became radioactively labelled (non-dialysable) and usually accounted for the majority of the incorporated radioactivity. Acetylcholine, dibutyryl cAMP and secretin stimulated radioactive incorporation into both gastric mucin and non-mucin components with acetylcholine and dcAMP stimulating specifically [3H] glucosamine into gastric mucin. Using these conditions no stimulation of incorporation into gastric mucin of all three radioactive precursors could be obtained with topical PGE2. In some biosynthesis studies by others, methods used to precipitate radioactive mucins do not distinguish between mucin and lower sized material. This study points to the need for a reappraisal of existing methods using radioactive isotopes to study mucin biosynthesis.

Animals↗
PubMed1989

Gastrointestinal mucus gel rheology.

Mucus secretions from human and pig stomach; pig duodenum and pig colon have the same viscoelastic gel structure, as determined by mechanical spectroscopy. These mucus gels are readily solubilised by proteolysis or reduction with thiol agents but are stable with an unchanged mechanical spectra following exposure to pH 1-8, bile, bile salts and hypertonic 2 M NaCl. Gels of the same mechanical spectra and stability are reproduced by concentration of the isolated mucins purified free of protein, DNA and lipid (less than 1%). A direct correlation is observed between percentage of total mucin in polymeric form in the mucus secretion and its gel quality. The mechanical spectra of proteolytically digested mucus, together with the resistance of mucus to denaturing agents suggest carbohydrate-carbohydrate interactions are involved in gel matrix formation. Pig submaxillary mucin forms model gels with the same viscoelastic gel structure as other gastrointestinal gels. Wide variations in the composition and length of the carbohydrate chains of mucins do not affect the gel-forming properties.

Animals↗