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Biomedical subjects

D Wahl

Publications and source records attributed to D Wahl.

108 records · Page 6Linked to original sources
PubMed1966

Programming of poliovirus inhibition of deoxyribonucleic acid synthesis in HeLa cells.

Ackermann, W. W. (The University of Michigan, Ann Arbor), and D. Wahl. Programming of poliovirus inhibition of deoxyribonucleic acid synthesis in HeLa cells. J. Bacteriol. 92:1051-1054. 1966.-Deletion of arginine from a culture medium reduced the rate of deoxyribonucleic acid (DNA) synthesis in uninfected HeLa cells. The normal rate was promptly restored by addition of arginine. Deletion of arginine also prevented poliovirus from inhibiting DNA synthesis in HeLa cells. However, the inhibitory potential of the infection and the capacity of the host cell for stimulation with regard to DNA synthesis were both retained in arginine-depleted cells which were infected. Upon addition of arginine late in the infection, DNA synthesis was first stimulated and then inhibited.

Arginine↗
PubMedDate not supplied

Assessment of deep vein thrombosis prophylaxis in surgical patients: a study conducted at Nancy University Hospital, France.

OBJECTIVE: This retrospective evaluation aimed to assess the adequacy of prophylaxis against thromboembolism prescribed to surgical patients at the authors' institution, and to compare it with generally accepted published guidelines. Aspects considered were indications for prophylaxis, regimens used and monitoring. METHODS: Eleven units (nine surgical and two surgical intensive care) took part in the survey on a voluntary basis. The clinical audit system used involved developing a set of criteria based on existing guidelines, comparing observed practice with those recommendations, analysing the factors underlying any deviation and developing corrective measures. RESULTS: When the medical records of 117 patients hospitalized in October 1995 were examined, prophylaxis against deep vein thrombosis was documented in 86 (low molecular weight heparin in 85, dextran in one). No associated physical preventative measures were recorded. Indications and dosage were appropriately handled in 90.7% and 75.2% of patients, respectively. Ninety-five cases were outside the reference criteria: 74 for excluded surgical indications, 13 which involved laparoscopy, and eight in which spinal or epidural anaesthesia was administered. Platelet count was performed in 73.8% of cases before prophylactic treatment, and in 23.10% during its course. Anti-Xa activity was measured in 0.4% of cases. Analysis of causes showed that guidelines were not complied with either because of lack of organization, or because of disagreement with them. DISCUSSION: In this study, indications for prophylaxis were well established and heparin dosages used were not fundamentally flawed. The weak point in practice was a failure to carry out platelet counts, particularly during the course of treatment. Appropriate corrective action consists of disseminating guidelines and relevant information, and using a preoperative checklist to assess thromboembolic risk. CONCLUSION: Physicians agree that opportunities to improve preventative practices exist, and that the quality improvement programme should be pursued.

Adult↗
PubMedDate not supplied

[Nailbed capillaroscopy in Crohn's disease].

It has recently been suggested that chronic mesenteric vasculitis was a pathogenetic mechanism in Crohn's disease. We have performed a prospective nailfold capillaroscopy study in seven patients with acute Crohn's disease. Minor nailbed abnormalities were frequently observed and three patients presented with major capillary dystrophy. These features are similar to those observed in some systemic vasculitis.

Adolescent↗
PubMedDate not supplied

[Lipids and lipoproteins in chronic alcoholism. Outcome after alcohol withdrawal].

The plasma lipids and lipoproteins changes observed in chronic alcoholic subjects and their modifications after cessation of drinking were studied in 379 patients admitted for alcohol withdrawal. The modifications were evaluated after one month (n = 348), 6 months (n = 56) and one year (n = 29) of abstinence. A significant decrease of HDL-cholesterol and apo A-I levels was noted after one year. HDL-cholesterol, apo A-I and apo B showed a biphasic variation with significant post-withdrawal changes which became less pronounced after 6 months of abstinence. The authors insist on the need for a prolonged post-withdrawal monitoring of plasma lipoproteins and apolipoproteins levels to evaluate the consequences of cessation of major chronic alcohol abuse. This study shows that the variations of plasma lipids and lipoproteins levels observed in heavy drinkers are similar to those observed in moderate drinkers, whereas the incidence of cardiovascular diseases seems to be higher in the former than in the latter.

Alcoholism↗
PubMedDate not supplied

Biomechanical comparison of bending and torsional properties in retrograde intramedullary nailing of humeral shaft fractures.

OBJECTIVE: To establish whether the bending and torsional stiffness of an implanted nail are influenced by nail design and nail-bolt interface, this study compared two implanted retrograde nail systems: the AO/ASIF unreamed humeral nail (UHN) and the Russell-Taylor (RT) nail. DESIGN: Pair randomization. SETTING: Mechanical laboratory testing. SPECIMENS: Twelve pairs of freshly harvested cadaveric humeri. METHODS: Transverse fractures were simulated with a standardized midshaft osteotomy and a three-millimeter gap. Both nails were proximally and distally interlocked. The RT nail has a single interlock at its base and tip. The UHN has double interlocking both proximally and distally. The screw hole design of the RT nail features slots, whereas the UHN has round screw holes. MAIN OUTCOME MEASURES: Anteroposterior and mediolateral bending stiffness and torsional stiffness. RESULTS: The RT nail showed higher bending stiffness in anteroposterior and mediolateral bending. Large differences were seen in the torsional characteristics: for the first 30 degrees, the RT nail showed a much lower resistance against torsion than the UHN. Analysis of variance of stiffness at four, six, and eight newton-meters showed statistical significance (p < 0.0001). Torsional stiffness, defined as the slope of a straight line approximated to between 75 and 100 percent of the maximum torque, was very similar in both nails. CONCLUSION: The torsional differences between the two nail systems are attributable to the nail-bolt interface of the RT nail. This dynamic system allows a clinically relevant degree of movement. The greater resistance to rotatory forces of the UHN is explained by the fact that the interlocking at its tip and base creates a static rather than a dynamic system.

Biomechanical Phenomena↗
PubMedDate not supplied

Improved intramedullary nail interlocking in osteoporotic bone.

OBJECTIVE: Intramedullary nail locking bolts often fail to gain purchase or cut out in osteoporotic bone. The biomechanical stability of a bladelike device that lowers intraosseous stress levels by distributing the load over a greater volume of bone was compared with conventional locking bolts in osteoporotic bone. METHODS: Standardized simulated comminuted supracondylar femoral fractures (segmental defect) in fresh-frozen paired osteoporotic (bone mineral density <200 milligrams per cubic centimeter) human cadaveric femurs were stabilized with a retrograde unreamed distal femoral nail and distally interlocked with conventional locking bolts or a bladelike device. The distal portions of the fixator-bone constructs were tested under axial load, and the stiffness and strength were compared (pairwise). RESULTS: Interlocking with a bladelike device was 41 percent stiffer (p = 0.01) and 20 percent stronger (p = 0.02) than that with conventional locking bolts. All posttesting radiographs showed compaction of the cancellous bone distal to the interlocking devices. Even after nail displacements of twelve millimeters, only a few locking bolts were plastically deformed and no bladelike device showed gross plastic deformation. CONCLUSION: This study showed the biomechanical benefits of increasing the bone-implant interface surface for improving the acute stiffness and strength of fracture fixation in osteoporotic cancellous bone. The fixator-bone construct withstood higher forces before failure in these fragile bones.

Aged↗
PubMedDate not supplied

[Prevention of venous thrombosis: role of heparins].

Prevention of venous thromboembolism is of major importance because deep vein thrombosis is an economic burden. To prevent pulmonary embolism, whether fatal or not, and the postphlebitic syndrome, virtually all patients' level of risk should be assessed in order to provide adequate prophylactic measures against venous thromboembolism. Non-pharmacological, pharmacological or combined modalities can reduce the frequency of venous thrombosis. Evidence-based guidelines are available for most situations in surgical patients. However, in medical patients there are fewer data and there are wide variations of opinion. Systematic reviews should be performed and updated to obtain practice guidelines. Cost and effectiveness as well as patients' preferences should be taken into account. Randomized control trials are ongoing: low-molecular-weight heparins are being evaluated in general medical patients; other forms of prophylaxis or combined methods are also being investigated.

Anticoagulants↗