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Biomedical subjects

J Davis

Publications and source records attributed to J Davis.

At least 325 records · Page 18Linked to original sources
PubMed1990

Density-gradient separation for 4-hydroperoxycyclophosphamide purging of autologous bone marrow grafts.

We studied density-gradient separation of autologous bone marrow grafts in preparation for ex vivo 4-hydroperoxy-cyclophosphamide (4-HC) purging. A two-step procedure of buffy coat isolation followed by Ficoll-diatrizoate separation was used. Buffy-coat cells were isolated primarily either using the COBE 2991 Blood Cell Processor or Haemonetics 30 Cell Separator. All density-gradient separations were performed using the COBE 2991. The nucleated cell recoveries after buffy-coat isolation were 44.3 +/- 10.4% and 85.1 +/- 10.5% (+/- standard deviation, P less than 0.001) for the Haemonetics 30 and COBE 2991 isolated grafts, respectively. The final nucleated cell recoveries after density-gradient separation for these two buffy-coat techniques were 24.2 +/- 10.1% and 29.5 +/- 14.7% (p = 0.30). Compared to manual density-gradient separation, the techniques using the COBE 2991 recovered slightly higher numbers of nucleated cells and CFU-GM. The red blood cell concentration of the 4-HC incubation mixture was 1.0 +/- 0.6% and the CFU-GM survival after treatment was 2.4 +/- 2.6%. The variability in CFU-GM survival after 4-HC incubation of the density-gradient separated grafts appears less than previous experience treating buffy-coat cells. Density-gradient separation of autologous bone marrow appears to provide a more uniform treatment with 4-HC and may improve the clinical transplant course of the autograft recipient.

Bone Marrow↗
PubMed1990

Toxicity of autologous bone marrow graft infusion.

We prospectively evaluated infusion-related toxicities in 70 patients undergoing autologous bone marrow transplantation. We studied symptoms, vital signs, forced vital capacities, and serum chemistry changes associated with the infusion. The bone marrow grafts were cryopreserved in 10% dimethylsulfoxide (DMSO) and stored in liquid nitrogen. All grafts were concentrated by centrifugation and the buffy-coat cells collected. Additionally, 20 grafts had mononuclear cells collected using density-gradients. Before infusion, the patients were medicated with hydration, mannitol, hydrocortisone, and diphenhydramine. The grafts were rapidly thawed and immediately infused without further manipulation. The mean volume infused to patients who received buffy-coat grafts was 6.3 +/- 1.7 ml/kg containing 0.7 +/- 0.2 gm/kg of DMSO. Patients who received density-gradient separated grafts received a product with a volume of 2.9 +/- 1.3 ml/kg containing 0.3 +/- 0.1 gm/kg DMSO. Symptoms included nausea, abdominal cramping, and flushing; patients who received buffy-coat grafts had more complaints. These patients also had mild increases in AST, ALT, and total bilirubin. Forced vital capacities were decreased in this group after the graft infusion; this change was not associated with the infusion of the density-gradient separated products. There was a significant difference (p less than 0.01) in heart rate and blood pressure changes associated with the infusions. Patients who received the larger product had a minimum heart rate of 63.3 +/- 12.4 BPM as compared to 80.7 +/- 18.0 BPM for the other patients. We found minor to moderate toxicities associated with the graft infusions, which were more severe in patients who received buffy-coat grafts. This could have resulted from the greater amounts of DMSO, cell lysis products, or volumes infused.

Adolescent↗
PubMed1989

Conserved repetitive epitope recognized by CD4+ clones from a malaria-immunized volunteer.

T cell clones obtained from a human volunteer immunized with Plasmodium falciparum sporozoites specifically recognized the native circumsporozoite (CS) antigen expressed on P. falciparum sporozoites, as well as bacteria- and yeast-derived recombinant falciparum CS proteins. The response of these CD4+ CD8- cells was species-specific, since the clones did not proliferate or secrete gamma interferon when challenged with sporozoites or recombinant CS proteins of other human, simian, or rodent malarias. The epitope recognized by the sporozoite-specific human T cell clones mapped to the 5' repeat region of the CS protein and was contained in the NANPNVDPNANP sequence.

Amino Acid Sequence↗
PubMed1989

Diversity in membrane binding sites of ankyrins. Brain ankyrin, erythrocyte ankyrin, and processed erythrocyte ankyrin associate with distinct sites in kidney microsomes.

This report presents evidence for diversity in membrane binding sites between three forms of ankyrin: brain ankyrin, erythrocyte ankyrin, and a variant of erythrocyte ankyrin (protein 2.2) present in circulating human erythrocytes that is missing a regulatory domain. These ankyrins were compared with respect to binding to kidney microsomes and exhibited the following behavior. 1) Brain and erythrocyte ankyrin each bind to distinct sites. 2) Protein 2.2 is an activated ankyrin that binds to all of the sites accessible to both brain and erythrocyte ankyrin and, in addition, associates with its own specialized sites. 3) The specificity of these membrane sites for various ankyrins is not absolute but reflects 2.5-10-fold differences in relative affinities. Further evidence that binding sites of different ankyrins share some common features is that the cytoplasmic domain of the erythrocyte anion transporter associates with all three ankyrins and displaces binding of the ankyrin variants to kidney membranes. The differences between erythrocyte and brain ankyrins in association with kidney membranes are likely to have physiological relevance to kidney because immunologically related isoforms of ankyrin are expressed in this tissue: erythroid ankyrin which is restricted to the basolateral domains of two cell types and a brain-related ankyrin expressed in all cells and present on apical as well as basolateral membrane surfaces. An unanticipated observation was the discovery of a membrane-associated ankyrin protease in kidney that is specific for erythrocyte ankyrin and may selectively activate the erythroid isoform of ankyrin. The variety of binding sites within this group of ankyrin proteins supports the idea that ankyrins are capable of linking a number of different membrane proteins to the spectrin-actin skeleton.

Animals↗
PubMed1989

The scintigraphic characteristics of ventricular pre-excitation through Mahaim fibers with the use of phase analysis.

The phase image pattern of blood pool scintigrams was blindly assessed in 11 patients exhibiting conduction through Mahaim pathways, including 6 nodoventricular and 5 fasciculoventricular. These patterns were compared with the phase image findings in normal subjects, patients with left and right bundle branch block in the absence of pre-excitation and patients with pre-excitation through atrioventricular (AV) connections. In all patients with a Mahaim pathway, the site of earliest phase angle was septal or paraseptal. Phase progression was asymmetric and the pre-excited ventricle demonstrated the earliest mean ventricular phase angle in 10 of 11 patients. This pattern, and the associated ventricular phase difference, appeared to vary from that in normal subjects and in those with a septal AV connection, in whom phase progression is generally symmetric. Scintigraphic phase analysis provided localizing information and presented patterns consistent with Mahaim pathways. Although not able to differentiate among Mahaim pathway subtypes, these phase patterns differed from those in normal subjects, those with right and left lateral free wall pathways and most patients with a septal AV pathway. However, the phase pattern of patients with a Mahaim pathway may not differ from that of patients with a septal AV connection displaying an asymmetric pattern of phase progression, or those with left and right bundle branch block in the absence of pre-excitation. Objective, yet imperfect phase measurements supported these differences. Such image findings may complement the often complex electrophysiologic evaluation of patients presenting with pre-excitation.

Adult↗
PubMed1989

The impact of in-house surgeons and operating room resuscitation on outcome of traumatic injuries.

As trauma systems develop, more patients can potentially benefit from immediate surgery. With in-house surgeons available, enthusiasm for direct transfer from the scene to the operating room (OR) has developed in many institutions. The purpose of this study was to define precisely which patients should be taken to the OR for resuscitation. Three hundred twenty-three patients were taken to the OR directly from the field during a 4-year period (6.9% of trauma activations). Indications included the following: (1) cardiac arrest--one vital sign present, (2) persistent hypotension despite field intravenous fluid, and (3) uncontrolled external hemorrhage. A board-certified surgeon and resuscitation team met the field transport team in the OR in all cases. Cardiopulmonary resuscitation for patients with blunt trauma was not accompanied by survival even with immediate surgery by a trained surgeon and it wastes valuable OR resources. Patients with prehospital hypotension unresponsive to fluid resuscitation indicate the need for rapid surgery. Patients with blunt injuries even with hypotension infrequently undergo operations in less than 20 minutes and can be resuscitated in traditional areas where better roentgenograms are obtained. Penetrating injuries to the chest and abdomen with hypotension are the primary indications for OR resuscitation. It can be anticipated with field communication and accompanied by enhanced survival.

Heart Arrest↗
PubMed1989

Case report of successful use of VP-16 in nasopharyngeal carcinoma.

We report the use of VP-16 as a single agent for the treatment of nasopharyngeal carcinoma. Our patient, a 16-year-old Black Haitian male, had complete clinical and radiographic response to VP-16. The remission continued for 14 months. The patient experienced minimal toxicity. We believe that the good response, excellent compliance, and minimal toxicity experienced by our patient should encourage more trials of VP-16 as upfront therapy for patients with nasopharyngeal carcinoma.

Adolescent↗
PubMed1989

Effects of intraoral prosthetics on swallowing in patients with oral cancer.

The swallowing patterns of four patients with oral cancer with intraoral palate reshaping/lowering protheses were studied with and without their prostheses 3 months postoperatively. The prostheses resulted in improved swallow efficiency, increased duration of tongue contact to the pharyngeal wall, and improved speed of movement of the bolus from the valleculae to the pyriform sinus. These results emphasize the effects of the tongue on the pharyngeal as well as oral stage of the swallow.

Deglutition↗
PubMed1989

Cystic hygroma presenting in adulthood.

We report a typical case of cystic hygroma presenting in an elderly female patient. A review of the literature on this condition reveals that although rare in adults, it should form part of the differential diagnosis of a cystic swelling in the neck in this group of patients as well as in the more commonly observed juvenile population. The embryology and pathogenesis of lymphangiomata are discussed as well as the recommended management of a cystic hygroma in an older patient.

Aged↗
PubMed1989

Preferential looking in the mentally handicapped.

We have assessed the feasibility of Preferential Looking (PL), using Teller Acuity Cards, for the estimation of binocular and monocular visual acuities in a group of mentally handicapped adults. Our results show the comparison between grating and recognition acuities, inter-observer variation, success rate, time taken and the sensitivity of this method in identifying monocular visual deficit in this group of subjects. The reasons for success or failure with PL methods in relation to criteria for mental handicap are discussed.

Adult↗
PubMed1989

Absorption of irrigating fluid during laser photocoagulation of the endometrium in the treatment of menorrhagia.

Twelve women undergoing laser ablation of the uterus for menorrhagia were studied by haemodynamic, biochemical and haematological indices including radioisotope dilution studies of plasma volume to assess the degree of fluid absorption into the circulation during laser surgery. There was a significant rise in central venous pressure and serum chloride and a significant decrease in plasma protein, albumin and haematocrit. Absorption of the irrigating fluid used was demonstrated and in one woman whose case history is illustrated this was excessive.

Absorption↗
PubMed1989

Steady-state plasma levels and pharmacokinetics of guanfacine in patients with renal insufficiency.

The steady-state pharmacokinetics and renal clearance of guanfacine were studied in patients with renal insufficiency. Apparent total body and renal clearances of guanfacine, as well as apparent volume of distribution, decreased in parallel with the decline in renal function. Higher plasma levels of guanfacine were observed in patients with GFR less than 30 ml/min. The steady state t 1/2 of guanfacine in the presence of renal insufficiency was insignificantly prolonged relative to that observed in the presence of normal renal function and appeared to be independent of the degree of renal insufficiency.

Adult↗