Maintenance and down-regulation of primed neutrophil chemiluminescence activity in human whole blood.

Priming of polymorphonuclear neutrophils (PMN) in whole blood (by tumor necrosis factor alpha and interleukin-8 for enhancement of luminol-dependent chemiluminescence induced by human complement-opsonized zymosan) was stable for 120 min. In contrast, priming of isolated PMN in plasma-free suspension for responses to opsonized zymosan, formyl-methionyl-leucyl-phenylalanine, and phorbol myristate acetate was markedly less stable. Decay of priming was not due to irreversible inactivation of the terminal CL production machinery because PMN could be reprimed by platelet-activating factor or leukotriene B4. The tumor necrosis factor-alpha-primed state of isolated PMN was stabilized by host plasma in a concentration-dependent fashion. We conclude that PMN priming results in a dynamic state that is reversible. Our findings suggest the existence of blood-borne components that may act to stabilize or modify PMN priming.

Comparison of late degenerative changes in porcine bioprostheses in the mitral and aortic valve position in the same patient.

Porcine bioprostheses implanted in both the mitral and aortic valve positions simultaneously in 5 patients aged 20 to 61 years (mean 45) were reexamined 18 to 107 months (mean 51) later. In 4 patients, the degenerative changes were distinctly more severe in the bioprostheses in the mitral than in the aortic valve position.

The beneficial effect of granulocyte colony-stimulating factor (G-CSF) in combination with gentamicin on survival after Pseudomonas burn wound infection.

Inadequate granulopoiesis and decreased granulocyte function are thought to play a significant role in the burned victim's susceptibility to infection. In an attempt to determine whether the regulatory granulopoietic growth factor G-CSF could favorably affect survival when used in combination with antibiotics, we examined survival in a murine model of Pseudomonas aeruginosa burn wound infection. One hundred twenty male BDF1 mice received a 15% total body surface area burn and were randomized to one of five treatment groups: (1) burn only, (2) burn + infection, (3) burn + infection + G-CSF, (4) burn + infection + gentamicin, and (5) burn + infection + G-CSF + gentamicin. Infected mice received a 10(3) colony-forming units topical inoculum of Pseudomonas to the wound immediately postburn. Gentamicin animals received 6.0 mg/kg intraperitoneal gentamicin as a single dose immediately postburn. G-CSF was administered as 100 ng twice daily for 7 days. All treatment groups showed improved survival compared with the burn + infection group, which showed 100% mortality by day 9 (p less than 0.001 all groups; Cox-Mantel statistic). Group 5 (burn + infection + G-CSF + gentamicin) exhibited improved survival as compared with either group 3 (burn + infection + G-CSF, p = 0.054) or group 4 (burn + infection + gentamicin, p = 0.007). The use of hematopoietic growth stimulants in combination with antibiotic therapy may result in improved outcome after burn injury, and it suggests new treatment options in the management of postburn infectious complications.

The effect of interleukin 1 alpha on survival in a murine model of burn wound sepsis.

We examined the effects of human recombinant interleukin 1 alpha (IL-1 alpha) in a murine model of burn wound sepsis. The BDF1 male mice received a 15% burn injury, followed by burn wound inoculation with Pseudomonas aeruginosa. Improvement in survival was noted in the mice that received a single injection of 100 or 1000 ng of IL-1 alpha in comparison with the control animals (IL-1 alpha, 100 ng vs control, 60% vs 13%; IL-1 alpha, 1000 ng vs control, 40% vs 0%). The animals that received 1 ng twice daily for 7 days had improved survival in comparison with the controls (IL-1 alpha vs control, 70.8% vs 20.8%). The animals that received a single injection of 1000 ng after a bacterial challenge with 10(4) P aeruginosa of IL-1 alpha had fewer positive blood cultures at 48 hours compared with the controls (57% vs 89%). In addition, the animals that received 100 ng of IL-1 alpha had significantly increased absolute neutrophil counts at 6, 24, and 48 hours after thermal injury and bacterial challenge with 10(3) colony-forming units of P aeruginosa. The use of cytokines to modulate the host response to injury or infection may lead to additional strategies to improve the outcome following burn injury.

Possible roles for anti- or pro-inflammatory therapies in the management of sepsis.

In the past few years we have greatly improved our understanding of the pathophysiologic mechanisms underlying the clinical syndrome of sepsis. As of this writing, however, this improved understanding has failed to result in the development of a single pharmacologic agent with clearly documented efficacy for improving outcome in septic patients. Research in this field, however, is yielding new insights on almost a daily basis, and it seems probable that the pharmacotherapy of sepsis and septic shock will undergo dramatic changes in the near future.

Quantitation of cat immunoglobulins in the hemolymph of cat fleas (Siphonaptera: Pulicidae) after feeding on blood.

Passage of ingested cat immunoglobulin G (IgG) into the hemocoel of cat fleas, Ctenocephalides felis (Bouché), was examined using antibody capture enzyme-linked immunosorbent assays (ELISA) and Western blotting. Fleas were fed heparinized cat blood via membrane feeders. Cat IgG was present in the hemolymph of engorged female fleas 1 h after ingestion at an estimated quantity of 35 +/- 14 micrograms/ml. The prevalence of fleas with demonstrable cat IgG in their hemolymph 1 h after feeding was 100% for both female and male fleas. Following a single blood meal, cat IgG was present in the hemolymph of all 15 fleas tested 1 h after ingestion but dissipated below detectable levels in 10 of 20 fleas examined 3 h after ingestion, and was detectable in only 1 of 10 fleas examined 18 h after ingestion. However, when fleas were provided with continual access to blood over a 72-h period, IgG content in hemolymph, as measured in excised, triturated legs of individual fleas, remained fairly constant (3-16 pg IgG per sample). Flea feeding studies using specific antisera indicated that IgG in flea hemolymph retained its binding activity, and that at least a portion of the IgG was intact. Passage of ingested host antibody from gut into hemocoel is a prerequisite for the possible development of antiflea vaccines that target antigens outside of the flea midgut lumen (e.g., key components of the flea endocrine system controlling oogenesis).

Screening for the potential pulmonary embolism victim.

The venous hemodynamics of 134 legs were evaluated using a bilateral impedance plethysmograph. Calf venous outflow following the release of proximal occluding cuffs and calf volume changes with ventilation were compared with the results of venography. We found that a two-second outflow of at least 65% indicated a patent deep venous system while an outflow of 50% or less indicated an obstruction of the proximal deep venous system. With outflow between 50% and 65%, a ventilatory wave height greater than 3 mm ruled out proximal deep venous obstruction while a height of 3 mm or less was not diagnostic. These two criteria yielded an accuracy of 92% with no false-negative results and a false-positive rate of only 10%. Thus, this technique can accurately rule out proximal deep venous obstruction and give the clinician considerable confidence in initiating anticoagulant therapy on those suspected cases with positive studies.

Toxic epidermal necrolysis: does immunoglobulin make a difference?

Experimental evidence implicates Fas ligand-mediated keratinocyte apoptosis as an underlying mechanism of toxic epidermal necrolysis syndrome (TEN). In vitro studies indicate a potential role for immunoglobulin (Ig) therapy in blocking Fas ligand signaling, thus reducing the severity of TEN. Anecdotal reports have described successful treatment of TEN patients with Ig; however, no study to date has analyzed outcome data in a large series of patients treated with Ig using institutional controls. The SCORTEN severity-of-illness score ranks severity and predicts prognosis in TEN patients using age, heart rate, TBSA slough, history of malignancy, and admission blood urea nitrogen, serum bicarbonate, and glucose levels. A retrospective chart review was performed that included all patients treated for TEN at our burn center since 1997. Ig therapy was instituted for all patients with biopsy-proven TEN beginning in January 2000. Twenty-one TEN patients were treated before Ig (no-Ig group), and 24 patients have been treated with Ig. SCORTEN data were collected, as well as length of stay (LOS) and status upon discharge. Each patient was given a SCORTEN of 0 to 6, with 1 point each for age greater than 40, TBSA slough greater than 10%, history of malignancy, admission BUN greater than 28 mg/dl, HCO3 less than 20 mg/dl, and glucose greater then 252 mg/dl. Outcome was compared between patients treated with Ig and without Ig. Overall mortality for patients treated before Ig was 28.6% (6/21), and with Ig, mortality was 41.7%% (10/24). There was no significant difference in age or TBSA slough. The average SCORTEN between the groups was equivalent (2.2 in no-Ig group vs 2.7 in Ig group, P = 0.3), and no group of patients with any SCORTEN score showed a significant benefit from Ig therapy. Overall LOS as well as LOS for survivors was longer in the Ig group. This series represents the largest single-institution analysis of TEN patient outcome after institution of Ig therapy. Our data do not show a significant improvement in mortality for TEN patients treated with Ig at any level of severity and may indicate a potential detriment in using Ig. Ig should not be given to TEN patients outside of a clinical trial. A multicenter, prospective, double-blinded randomized trial is necessary and urgently indicated to determine whether Ig therapy is beneficial or harmful in the care of TEN patients.

Effects of changes in power setting of an ultrasonic aspirator on amount of damage to the cerebral cortex of healthy dogs.

OBJECTIVE: To determine the minimal ultrasonic aspirator pressure necessary to damage the cerebral cortex of healthy dogs. ANIMALS: 9 mixed-breed dogs. PROCEDURE: The study comprised 2 parts. In part A, 6 dogs were euthanatized immediately prior to the experiment. In part B, 3 dogs were anesthetized for recording of physiologic variables. In both parts, craniectomy and durotomy were performed to bilaterally expose the lateral aspect of the cerebral cortex. An ultrasonic aspirator was placed in contact with various areas of the cerebral cortex, and aspirator power was altered (10, 20, 30, and 40%). Duration of contact at each power was 5 and 10 seconds. Subsequently, gross morphologic and histologic damage was assessed in the cortex. RESULTS: Gross observations for all dogs were similar. At 10% power, visible or histologic damage was not evident in the cortex. At 20% power, the cortex was slightly indented from contact with the hand piece; however, cortical disruption was not evident. Cortical disruption was initially detectable at 30% power in some dogs and was consistently evident at 40% power in both sets of dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonic aspirator power of < 20% created minimal acute morphologic damage to the cortex. Power settings between 20 and 30% may superficially damage the cerebral cortex in healthy dogs, whereas 40% power consistently damages the cerebral cortex. Knowledge of the degree of damage to cerebral cortex caused by various amounts of power for ultrasonic aspirators will allow surgeons to avoid damaging normal brain tissues during surgery.

Scoliosis and associated cystic spinal cord lesion in a dog.

A 7-month-old female Mastiff was admitted for weakness in the hind limbs and an abnormal gait. There was an obvious scoliosis in the midlumbar region. Using electromyography, fibrillation potentials and positive sharp waves were found in the epaxial musculature of the vertebral column lateral to the spinous processes of Tl3-L4 on the right (convex) side of the body. On myelographic evaluation, contrast medium irregularly filled the subdural and epidural space of Tl1-L3. On surgical examination, the dog had a cystic lesion of the spinal cord that correlated with myelographic findings. This lesion was incised and drained. The scoliotic defect was surgically straightened, and the affected vertebrae were fused. Six months after surgery, the vertebral column continued to be straight and the paraparesis had resolved.

Clinical signs associated with brain tumors in dogs: 97 cases (1992-1997).

OBJECTIVE: To determine the prevalence of various clinical signs in dogs with brain tumors. DESIGN: Retrospective study. ANIMALS: 97 dogs with brain tumors. PROCEDURE: Medical records were reviewed for signalment, tumor type and location, and clinical signs. RESULTS: 33 breeds were represented; Golden Retrievers were most commonly affected. Most dogs were older (median age, 9 years); 95% of dogs were > or = 5 years old. Seventy-six percent of dogs had tumors in the supratentorial region. Seizures were the most common clinical sign at initial examination, with lower prevalence for circling, ataxia, and head tilt. Meningioma was the most common tumor. CONCLUSIONS AND CLINICAL RELEVANCE: Brain tumors develop most often in dogs > or = 5 years old and are uncommon in dogs < 5 years old. Seizures are a common clinical sign, and a brain tumor should be considered in dogs that have their first seizure after they are 4 years old.

Characterization of aspen isoprene synthase, an enzyme responsible for leaf isoprene emission to the atmosphere.

Isoprene (2-methyl-1,3-butadiene) is a volatile hydrocarbon emitted from many plant species to the atmosphere, where it plays an important role in atmospheric chemistry. An enzyme extracted from aspen (Populus tremuloides) leaves was previously found to catalyze the Mg(2+)-dependent elimination of pyrophosphate from dimethylallyl diphosphate (DMAPP) to form isoprene (Silver, G. M., and Fall, R. (1991) Plant Physiol. 97, 1588-1591). This enzyme, isoprene synthase, has now been purified 4000-fold to near homogeneity. The enzyme had a native molecular mass of 98-137 kDa and isoelectric point of 4.7 and contained 58- and 62-kDa subunits, implying that it is a heterodimer. Partial amino acid sequences of the two subunits indicated they are closely related to each other and that they do not share a strong homology with any other reported proteins. The isoprene synthase reaction was dependent on Mg2+ or Mn2+, and the reaction products were shown to be isoprene and pyrophosphate with a stoichiometry close to 1:1. The Km for DMAPP was high at 8 mM, and the kcat of 1.7 s-1 was low, but similar to those of other allylic diphosphate-utilizing enzymes. It is argued that the isoprene synthase reaction may be much more efficient in vivo, where it is under light-dependent control. It seems probable that this unique enzyme, rather than non-enzymatic reactions, can account for the emission of hundreds of millions of metric tons of isoprene from plants to the global atmosphere each year.

Enzymatic synthesis of isoprene from dimethylallyl diphosphate in aspen leaf extracts.

Aspen (Populus tremuloides Michx.) leaf extracts contain a newly discovered enzyme activity that catalyzes the magnesium ion-dependent elimination of diphosphate from dimethylallyl diphosphate with rearrangement to form isoprene (2-methyl, 1-3-butadiene). This isoprene synthase activity has been partially purified. The nonenzymatic reaction of dimethylallyl diphosphate to isoprene, known to be acid catalyzed, may be insignificant at physiological pH. In contrast, the enzymatic reaction may be responsible for the majority of light-dependent isoprene production by isoprene-emitting plants.