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Biomedical subjects

K Allen

Publications and source records attributed to K Allen.

At least 91 records · Page 5Linked to original sources
PubMed1993

Attitudes of registered nurses toward alcoholic patients in a general hospital population.

The Marcus Alcoholism Questionnaire was administered to 66 registered nurses at a community hospital to ascertain their attitudes regarding alcoholic patients in a general hospital population. This was done to provide documentation on what nurses attitudes actually are as opposed to making an assumption about what they should be because of the high visibility of the problem of alcoholism. The author reports the results of the study and then contrasts them with information about registered nurses attitudes toward alcoholic patients at a university hospital. The article concludes with insight into contributing factors for the differences.

Alcoholism↗
PubMed1993

Modulation of the activity of calpain II by phosphorylation--changes in the proteolysis of cyclic AMP-dependent protein kinase (peak II, DEAE).

The proteolysis of the 32P-labeled holoenzyme of cyclic AMP-dependent protein kinase (A-PKII:DEAE, peak II fraction) was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The contaminants of the A-PKII and calpain II apparently did not interfere with the accuracy of this highly sensitive analysis. Phosphorylation of calpain II by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) greatly enhanced the proteolysis of A-PKII, whereas phosphorylation by protein kinase C (PK-C) or cyclic GMP-dependent protein kinase (G-PK) slightly altered the proteolysis.

Calpain↗
PubMed1993

Regulation of the phosphorylation of histones and glycogen synthase.

The phosphorylation of histones and glycogen synthase by protein kinases was analysed by SDS-polyacrylamide gel electrophoresis and autoradiography. The phosphorylation of histone III-S by the catalytic subunit of cyclic AMP-dependent protein kinase (A-PK) or cGMP-dependent protein kinase (G-PK) was inhibited by archidonic acid, sphingosine and staurosporine. Using the catalytic subunit of A-PK, the phosphorylation of histone VIII-S was inhibited by Ca2+, arachidonic acid and staurosporine; the phosphorylation of histone II-S was inhibited by phosphatidyl ethanolamine, phosphatidyl inositol, arachidonic acid and staurosporine; and the phosphorylation of glycogen synthase was inhibited by arachidonic acid and staurosporine. After being phosphorylated by the catalytic subunit of A-PK, calpain II with 4 microM Ca2+ was less effective in degrading histone III-S, which had been prephosphorylated by PK-C.

AMP-Activated Protein Kinases↗
PubMed1993

Applications of NMR spectroscopy to the study of experimental stroke in vivo.

BACKGROUND AND PURPOSE: Magnetic resonance spectroscopy and imaging enable us to investigate biochemical and pathophysiological changes associated with cerebral ischemia. The specific aims of these studies were to establish the relationships between energy metabolites and regional cerebral blood flow and to determine whether diffusion-weighted imaging is sensitive to the known thresholds for cerebral tissue energy failure and disturbance of transmembrane ionic gradients in gerbils. METHODS: Magnetic resonance spectroscopy measurements of energy metabolites in the gerbil brain were obtained as a function of cerebral blood flow (measured with the hydrogen clearance technique) before, during, and after unilateral or bilateral occlusion of the common carotid arteries. Diffusion-weighted and T2-weighted images were obtained in a separate series of experiments. RESULTS: Major changes in brain energy metabolites were observed at flow values of 20 ml.100 g-1.min-1 and below. The cerebral blood flow threshold for maintenance of energy status was lowered in hypothermia, consistent with a protective effect. Diffusion-weighted imaging intensity increased at cerebral blood flow values of 15 to 20 ml.100 g-1.min-1 and below and increased gradually following the onset of severe global cerebral ischemia, but with a delay of about 2.5 minutes. CONCLUSIONS: The spectroscopic observations suggest that the flow thresholds for electrical function and edema are a direct consequence of energy failure. Comparison of the spectroscopy and imaging data suggests that diffusion-weighted imaging is sensitive to disruption of tissue energy metabolism or to a consequence of this disruption. The possibilities arise of visualizing energy failure with the spatial resolution characteristic of magnetic resonance imaging and detecting compromised but recoverable tissue.

Animals↗
PubMed1992

Prostacyclin production from seeded prosthetic vascular grafts.

Endothelial cell seeding has been proposed as a method of improving patency rates in small-calibre prosthetic vascular grafts. In vivo, endothelial cells normally produce prostacyclin (PGI2), a potent antiplatelet agent. The aim of this study was to determine whether seeded grafts show significant PGI2 production after in vivo implantation. Grafts were seeded with either autologous canine venous endothelial cells or autologous microvascular endothelial cells. After 12 weeks, PGI2 production was assessed under basal and stimulated conditions. Seeded grafts were compared with non-seeded controls and the corresponding aorta. The overall patency rate in seeded grafts was 80 per cent compared with 10 per cent in non-seeded grafts (P < 0.01). Grafts seeded with cells from either source produced significantly more PGI2 than unseeded grafts in both basal and stimulated states (P < 0.05). The aorta produced significantly more PGI2 than seeded grafts under both conditions (P < 0.01). Endothelial cell seeding produces a functional graft and leads to an improved patency rate.

Animals↗
PubMed1992

Patterns of failure following combined modality therapy for esophageal cancer, 1984-1990.

From 1984-1990, 143 patients with squamous cell or adenocarcinoma of the esophagus were enrolled in a Phase I/II study of neoadjuvant chemotherapy followed by concurrent chemotherapy plus radiotherapy with or without subsequent esophagectomy. Patients received one cycle of Cisplatin or Carboplatin plus Etoposide for squamous cell carcinoma, or Cisplatin or Carboplatin plus 5FU for adenocarcinoma, followed by two cycles of the same chemotherapy given concurrently with 44-46 Gy over 5 weeks. Operable patients then underwent esophagectomy. Inoperable patients and those with positive surgical margins received additional irradiation (16-18 Gy). Twelve percent of the surgical group received preoperative radiotherapy doses > or = 50 Gy. Seventy-two percent (103) had clinical Stage I-III tumors and 28% (40) were clinical Stage IV (1983 American Joint Committee on Cancer criteria). Only clinical Stage I-III patients were analyzed with respect to patterns of failure. Isolated local failure occurred in 19/103 (18%) of clinical Stage I-III patients. Both local and distant relapse occurred in 15/103 (15%), and distant metastases alone occurred in 25/103 (24%). The 3-year actuarial rates of local and distant failures were 45% and 60%, respectively. Among the clinical Stage I-III patients who underwent surgery (n = 58) versus those who did not (n = 45), the 3-year actuarial local and distant failure rates were 30% versus 60% and 45% versus 45%, respectively. Multivariate analysis was performed to identify significant predictors of local control. For all clinical Stage I-III patients, treatment with surgery (p = 0.001) and with three or more cycles of chemotherapy (p = 0.02) were significant predictors of improved local control. Patients who underwent surgery were significantly younger and had a better performance status than those who did not. The improvement in local control with surgery did not translate into better survival, likely on account of a high operative mortality rate in older patients and those receiving > or = 50 Gy preoperatively. We conclude that local control remains poor with concurrent chemotherapy + radiotherapy for esophageal cancer. The addition of surgery improved local control, but distant metastases remain a problem both in this group of patients as well as those treated without esophagectomy. Efforts to improve local control appear warranted, but it remains to be demonstrated that improved local control translates into improved survival in esophageal cancer because of a high rate of distant metastases in patients whose disease is controlled in the esophagus.

Adenocarcinoma↗
PubMed1992

Disruption of pioneer growth cone guidance in vivo by removal of glycosyl-phosphatidylinositol-anchored cell surface proteins.

Cell surface proteins anchored to membranes via covalently attached glycosyl-phosphatidylinositol (GPI) have been implicated in neuronal adhesion, promotion of neurite outgrowth and directed cell migration. Treatment of grasshopper embryos with bacterial phosphatidylinositol-specific phospholipase C (PI-PLC), an enzyme that cleaves the GPI anchor, often induced disruptions in the highly stereotyped migrations of peripheral pioneer growth cones and afferent neuron cell bodies. In distal limb regions of embryos treated with PI-PLC at early stages of pioneer axon outgrowth, growth cones lost their proximal orientation toward the central nervous system (CNS) and turned distally. Pioneer growth cones in treated limbs also failed to make a characteristic ventral turn along the trochanter-coxa (Tr-Cx) segment boundary, and instead continued to grow proximally across the boundary. Treatment at an earlier stage of development caused pre-axonogenesis Cx1 neurons to abandon their normal circumferential migration and reorient toward the CNS. None of these abnormal phenotypes were observed in limbs of untreated embryos or embryos exposed to other phospholipases that do not release GPI-anchored proteins. Incubation of embryos with PI-PLC effectively removed immunoreactivity for fasciclin I, a GPI-anchored protein expressed on a subset of neuronal surfaces. These results suggest that cell surface GPI-anchored proteins are involved in pioneer growth cone guidance and in pre-axonogenesis migration of neurons in the grasshopper limb bud in vivo.

Animals↗
PubMed1992

Effect of x-ray angulation on radiographic periodontal ligament space width.

The aim of this study was to set up a model for quantitating a change in radiographic PDL width on variation of x-ray angulation within anticipated clinical limits. Four incisor and 4 molar sites of 6 human skulls were radiographed at varying angulation. Horizontal angulation changes were made over a 12 degrees range, in 3 degrees increments. Vertical angulation change was in one 10 degrees increment. Baseline radiographs were taken with the x-ray beam perpendicular to a buccal tooth surface in a horizontal direction and perpendicular or 10 degrees off the perpendicular in a vertical direction. The radiographs were converted to digitized images and PDL width measurements made utilizing a mouse-driven computer program. The mean PDL width differences between all possible horizontal and vertical combinations (n = 45) were compared with the mean of those obtained from differences observed in PDL width measurements on replicate baseline radiographs. Mean PDL width differences for incisor locations were statistically different from the mean baseline PDL width difference; posterior PDL width difference showed no statistical variation from the mean baseline PDL width difference. For radiographs taken within the range expected under clinical conditions, a significant change in PDL width may be observed in incisor locations. Posterior sites may not exhibit this significant change due to the anatomy of the region which may reduce the clarity of the radiographic image.

Humans↗
PubMed1992

Computerized methodology for detection of alveolar crestal bone loss from serial intraoral radiographs.

The aim of this study was to develop a computerized measurement system for analysis of unstandardized serial radiographic images. A new approach for estimating the error associated with the determination of alveolar crest loss is described. The study shows that a difference of 0.87 mm in cemento-enamel junction-crest measurement between unstandardized serial radiographs taken within accepted clinic routine is required for a significant loss in crestal bone height. The ability to detect with significance a difference of less than 1 mm in crestal bone height makes the appropriate use of traditional bite-wing radiographs a useful diagnostic tool for the assessment of periodontal maintenance.

Adolescent↗
PubMed1992

Establishing reliability of the Community Oriented Program Environment Scale on chemically-dependent black females.

Research instruments are often used on samples without determining their reliability for that group of subjects. As a result, information is disseminated that really has no scientifically sound base. Thirty chemically-dependent Black females were chosen as subjects to determine reliability of the Community Oriented Program Environment Scale on this population. They were administered the instrument, and reliability was obtained using the Kuder-Richardson 20 internal consistency test. Findings showed low overall reliability and extremely low subscale reliability on this sample. It was concluded that this instrument would yield uninterpretable data in looking at attrition and treatment environment with this population.

Adult↗
PubMed1991

A prospective longitudinal study of observation versus surgical intervention in the management of necrotizing pancreatitis.

Pancreatic necrosis is now recognized as a principal determinant of survival in acute pancreatitis. However, it is currently unknown how frequently pancreatic necrosis develops in acute pancreatitis, how often pancreatic necrosis becomes secondarily infected, and whether sterile pancreatic necrosis represents an indication for surgery or can be treated by conservative means. In 194 patients with unequivocal acute pancreatitis, pancreatic necrosis developed in 38 (20%), as documented by dynamic pancreatography, and was confirmed by histologic diagnosis at surgery in 28. All patients were prospectively treated by medical means. Patients with pancreatic necrosis who remained persistently febrile underwent fine needle aspiration for bacterial culture. Infected pancreatic necrosis was demonstrated in 27 of the 38 patients (71%) with pancreatic necrosis and was treated by open drainage, yielding a mortality rate of 15%. All 11 patients with demonstrated sterile pancreatic necrosis, including 6 with pulmonary and renal insufficiency, were successfully treated without surgery. Pancreatic necrosis occurs in approximately 20% of patients with acute pancreatitis and is necessary for the development of secondary pancreatic infection. However, pancreatic necrosis by itself, even when accompanied by organ failure, is not an absolute indication for surgery. A trial of medical treatment for all patients with sterile pancreatic necrosis is in order.

Acute Disease↗
PubMed1991

Binding of anti-acetaldehyde IgG antibodies to hepatocytes with an acetaldehyde-phosphatidylethanolamine adduct on their surface.

We have previously shown that antibodies raised against acetaldehyde adducts of protein cross-react with an acetaldehyde adduct of dioleoylphosphatidylethanolamine, N-ethyl-dioleoylphosphatidylethanolamine, when the latter is incorporated into hexagonal phase phospholipid micelles. In the present study we demonstrate that these same IgG antibodies cross-react with N-ethyl-dioleoylphosphatidylethanolamine when this adduct is incorporated into the surface of hepatocytes. Hapten-specific IgG antibodies were purified from the sera of rabbits sensitized to an albumin-acetaldehyde conjugate that had been reduced with sodium cyanoborohydride (N-ethyl-RSA). The N-ethyl-RSA was coupled to an Affi-Gel-10 column to affinity purify the IgG. Liposomes containing N-ethyl-dioleoylphosphatidylethanolamine were fused with isolated hepatocytes, the affinity purified primary IgG antibodies were added, then fluorescein-conjugated second antibodies were added, and antibody binding to hepatocytes was measured by flow cytometry. The fluorescence of these hepatocytes was significantly greater (p less than 0.01) than control hepatocytes prepared with (1) pre-immune primary IgG antibodies with fluorescein-conjugated second antibodies, (2) no primary antibody but with fluorescein-conjugated second antibodies, and (3) no fluorescein-conjugated second antibodies.

Acetaldehyde↗
PubMed1991

What alveolar crest level on a bite-wing radiograph represents bone loss?

In advanced periodontal disease alveolar bone crestal loss is readily apparent on radiographs. However, in incipient disease there is a lack of consensus regarding what constitutes crestal bone loss on a radiograph. To properly assess crestal bone loss radiographically requires an appropriate base of reference indicative of the absence of destructive periodontal disease. In this study the radiographic CEJ-crest distance as a measure of crest height was determined for sites at which clinical attachment measurements indicate no attachment loss. From these measurements it is concluded that no crestal bone loss is consistent with a range of radiographic CEJ-crest distance between 0.4 and 1.9 mm (95% confidence limits) as evidenced on bite-wings.

Adolescent↗