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T R Graham

Publications and source records attributed to T R Graham.

At least 73 records · Page 4Linked to original sources
PubMed1989

Artificial hearts.

Explore the source record for details and available documents.

Assisted Circulation↗
PubMed1989

A concealed impalement injury of the chest--an unusual intrathoracic foreign body.

Penetrating injuries of the chest in civilian practice are rare. A case is presented of an unusual injury with a large wooden chair fragment which remained concealed for several days until the development of life threatening complications. Aspects of the evaluation of penetrating thoracic injuries are discussed.

Acute Kidney Injury↗
PubMed1989

Temporary mechanical ventricular support: Part 1.

Temporary mechanical circulatory support is currently indicated in postcardiotomy cardiogenic shock and if necessary as a bridge to cardiac transplantation. This support is presently required in 1% of adult patients undergoing cardiac surgery. Cardiac function and quality of life in long-term survivors following hospital discharge has been excellent.

Assisted Circulation↗
PubMed1989

Temporary mechanical ventricular support: Part 2.

Temporary mechanical circulatory support is currently indicated in postcardiotomy cardiogenic shock and if necessary as a bridge to transplantation where no ventricular recovery is expected. Which mechanical support system to employ as a bridge to transplantation remains debatable. Implantable devices presently used are prototypes of proposed permanent devices for the treatment of severe heart failure in patients for whom transplantation is not suitable or available.

Assisted Circulation↗
PubMed1988

Molecular cloning of the cDNA which encodes beta-N-acetylhexosaminidase A from Dictyostelium discoideum. Complete amino acid sequence and homology with the human enzyme.

beta-N-Acetylhexosaminidase A (EC 3.2.1.52), the product of the nag A gene, is a lysosomal enzyme which is developmentally regulated in Dictyostelium discoideum. The enzyme plays a role during the slug stage of development in the maintenance of pseudoplasmodia of normal size. We used a homogeneous preparation of deglycosylated enzyme subunits to generate antibody. The antibody was suitable for screening a lambda gt11 cDNA expression library derived from the mRNA of late log stage axenic cells. We isolated seven positive clones. One of these contains the complete coding sequence of the protein. We also isolated a genomic clone which contains 800 base pairs of 5'-flanking sequence and 728 base pairs of coding sequence. Analysis of the sequences and of primer extension studies indicates an inferred transcript size of 1665 bases which closely matches the 1.8-kilobase mRNA size estimated by Northern blot analysis of poly(A+) mRNA from the organism. The sequence contains an open reading frame which encodes a protein of 59,787 kDa. This equals the apparent molecular weight in sodium dodecyl sulfate-polyacrylamide gels of in vitro translated enzyme. The amino terminus of the purified enzyme appeared to be blocked, but internal peptide sequences were obtained by automated Edman degradation of gel-purified peptides generated by treatment of protein subunits with staphylococcal V-8 protease. These sequences are included in the inferred sequence. In addition to a typical signal sequence, the open reading frame encodes a second candidate transmembrane region, a serine-rich region, and four potential N-glycosylation sites. These are discussed with regard to the localization and processing of the enzyme during its biogenesis. Beginning at amino acid 100 of the Dictyostelium enzyme sequence, 36% of its amino acids are identical to the corresponding sequence of the beta chain, and 33% are identical with those of the alpha chain of human beta-N-acetylhexosaminidase. This is strong evidence that the Dictyostelium enzyme is homologous to the alpha and beta chains of the human enzyme.

Amino Acid Sequence↗
PubMed1984

The effect of accelerated lactation on fetal maintenance in the rat.

Rats mated post partum were permitted to nurse 2 pups until day 9, at which time laparotomy was performed and the number of implantation sites counted. Control animals were left to nurse 2 pups or none, while lactation was then accelerated in 4 other groups by the addition of more pups to totals of 3, 5, 7 or 9. On day 19 the mothers were killed and the fetuses counted, weighed and checked for normality. With increased lactational demand the proportion of fetuses maintained decreased. Total fetal weight was decreased significantly only when 7 or more pups were being nursed. Individual fetal weights and normalcy were not affected by accelerated lactation.

Animals↗
PubMedDate not supplied

An ambulatory, intermediate term left ventricular assist device.

A portable, percutaneous, battery-operated left ventricular assist device intended for intermediate and long-term use is described. The system performed satisfactorily in vitro for periods of up to 9 months and in vivo for periods in excess of 3 months. Long-standing hypertension was observed in a 98 day implant with accompanying renal and visceral vascular changes. No evidence of peripheral thromboembolism was seen. Examination of the textured blood pump surface revealed an established biologic lining, characteristic of that previously seen in calves with some evidence of peripheral calcification.

Ambulatory Care↗
PubMedDate not supplied

Pentoxifylline preloading reduces endothelial injury and permeability in cardiopulmonary bypass.

Pentoxifylline (PTX), a methyl xanthine derivative, reduces endothelial permeability. A double blind, prospective, randomized, placebo controlled, parallel study was undertaken to assess the effect of PTX on leukotriene B4, complement fragment C3a, interleukin 6 (IL6), endothelial injury as measured by von Willebrand factor (vWf), and endothelial permeability as measured by urinary albumin excretion (expressed as excreted urinary albumin to creatinine ratio [ACR]) in patients undergoing cardiopulmonary bypass (CPB) for elective coronary artery bypass grafting. Twenty patients were recruited into each treatment arm and given either PTX 400 mg or placebo three times daily for 1 week before surgery. Patients were well matched. All operations were performed using one anesthetic, CPB, and a myocardial protection technique. Blood and urine samples were taken after anesthetic induction (baseline); 20 min after the start of CPB; 5 min after removal of the cross clamp; and 5 min and 2, 6, and 24 hr after the end of CPB. Pentoxifylline did not reduce IL6, C3a, and LTB4 release but reduced Factor VIIIRAg and urinary albumin excretion preoperatively (PTX vs placebo, ACR 1q.0 vs 2.1 mg/mmol, vWf 0.8 vs 1.3 IU/ml, p < 0.05) and peak levels (PTX vs placebo, ACR 8.9 vs 16.2, vWf 1.2 vs 2.2, p < 0.05) after CPB. These results suggest that PTX may attenuate the endothelial injury and permeability seen in CPB.

Albuminuria↗
PubMedDate not supplied

Lipid tolerance in the very low birth weight infant on intravenous and enteral feedings.

Nutrition is of critical importance to very low birth weight (VLBW) survival. Intravenous (iv) lipid tolerance has been studied using a soybean or safflower-based lipid emulsion. We studied lipid levels in a group of VLBW infants on both intravenous lipids (soybean-safflower emulsion) and on enteral feedings (24 cal/oz premature formula). Levels were obtained on 1, 2, and 3 g/kg/day of iv lipid and after 3 and 10 days of feeding. Triglyceride (TG) and free fatty acid (FFA) proved the most sensitive indicator of both iv and enteral tolerance. The higher the lipid dose, the more likely there would be elevated lipid levels, especially FFA. Mean lipid levels for the group of enteral-fed infants were normal. Comparison of lipid levels on iv to those on enteral feedings showed significant differences in trough iv levels of TG compared to preprandial TG. FFAs tended to be significantly higher on iv feedings. Monitoring lipid levels on iv and enteral feedings is appropriate to document tolerance.

Drug Tolerance↗
PubMedDate not supplied

In vitro evaluation of an implantable left ventricular assist device.

The development of implantable left ventricular assist devices (LVADs) has almost reached the stage of providing permanent circulatory support in patients who are unsuitable for, or denied, the transplant option. As part of our ongoing haemodynamic evaluation of the Thermo Cardiosystems Inc. (Boston, USA) Mark 14 pneumatic LVAD, pressure-volume loops have been produced from in vitro studies using a modified National Heart Lung and Blood Institute (NHLBI, USA) mock circulatory loop. These studies have demonstrated that during certain phases of the pump cycle non-physiologically high and low pressures are generated within the LVAD. Such abnormal pressures may damage either the bioprosthetic valves in the LVAD or the native heart, and may have adverse effects on cardiovascular control mechanisms.

Evaluation Studies as Topic↗
PubMedDate not supplied

Development of a polyurethane percutaneous access device for long-term vascular access.

The percutaneous placement of intravascular devices creates a portal for microbial invasion that can result in local infections or septicemia. In nature, resistance to "exist site" infection in percutaneous organs, such as teeth, is prevented by a dense collagen/epithelial barrier. A new percutaneous access device has been developed that incorporates a porous polyurethane "button" at the subdermal level. This device promotes the development of a collagen/epithelial interface, thus inhibiting sinus formation. Twelve percutaneous access devices (PCADS) were implanted in calves; eight devices were utilized for venting of, and hard wire passage to, an implantable left ventricular assist device (LVAD) and served as controls. Four devices were utilized for long-term vascular access. The PCADS remained in situ for 2-127 days (mean 70). Excellent healing was apparent in all cases, and no exit site or catheter related infections occurred. Histologic examination demonstrated fibroblastic in-growth and collagen deposition within the porous polyurethane, which provides a barrier to epithelial migration and firmly anchors the device. These PCADS appear to reduce exit site infections and may improve upon currently available long-term vascular access catheters.

Animals↗