Thromboxane A2 and Prostacyclin Release in Bleeding Time Blood during Primary Haemostasis in Healthy Individuals

ABSTRACT It is generally believed that prostacyclin (PGI₂) generation is greatly stimulated when blood vessels are injured, even by minor trauma, such as venepuncture. The Simplate technique for measuring skin bleeding time was adapted to quantify by radioimmunoassay PGI₂ and thromboxane A₂ (TXA₂) in the emerging blood, as the stable degradation products 6-keto-prostaglandin F_1α (6-keto-PGF_1α) and thromboxane B₂ (TXB₂), both of which were measured in venous plasma as well as in serum (clotted at 37°C for 1 h). During bleeding, when platelets aggregate to occlude the injured vessels, the median TXB₂ level in the emerging bleeding time blood was 1.7 ng/ml. The median TXB₂ level in plasma was < 1 ng/ml and in serum 275 ng/ml. The levels of immunoreactive 6-keto-PGF_1α were always below determination limit in bleeding time blood (0.2 ng/ml) and in plasma (0.1 ng/ml), whereas in serum the levels ranged between 0.26 and 0.47 ng/ml. The fact that enhanced PGI₂ production in primary haemostasis in skin incisions could not be demonstrated calls for further investigations of possible PGI₂ production with more sensitive assays or in injured large vessels.     

Intensity of Jogging

The relationship between intensity of jogging and various menstrual/reproductive factors in women were investigated. Data were collected by questionnaire from 319 women who participated in a running event that included both a 6.2-mile (10 K) run and a 26.2-mile marathon in northeastern Ohio. Findings reaffirmed the notion that scant menstrual flow, skipped menses, and menstrual irregularity are significantly related to the intensity of jogging; age at menarche, infertility, and uterine prolapse were not. Thirty-two percent of the women felt that jogging decreased their menstrual discomfort, and 44% reported better jogging performance right after or between menstrual periods.     

Influence of Lead on Mineralization during Bone Growth

Lead will inhibit skeletal development and localize in areasof bone formation and resorption, but the mechanisms of leadtoxicity in bone are largely unknown. This study used an ectopicbone (plaque) induction method to investigate the effect oflead on mineralization of cartilage in growing bone. Demineralizedbone matrix was subcutaneously implanted in male Long-Evansrats to induce plaque formation. Of 64 rats which were provideddeionized water, 32 were implanted with control matrix (controlgroup). The remaining 32 rats were implanted with matrix containinga target concentration of 200 µg lead/g of plaque tissueas ectopic bone (lead-added group). Another group of 32 ratswas continuously exposed to 1000 ppm lead in drinking waterand subcutaneously implanted with control matrix (drinking water-leadgroup). Plaques were taken for analysis on Days 8 and 12 postimplantation.Alkaline phosphatase activity and cartilage mineralization wereobliterated in lead-added plaques. However, calcium depositionwas markedly enhanced in the lead-added plaques. Decreased alkalinephosphatase in Day 8 drinking water-lead plaques followed increasedDay 12 drinking water lead plaque calcification. Enhanced cartilagecalcification and reduced alkaline phosphatase activity in thedrinking water-lead plaques was consistent with effects observedin the metaphyseal regions of bone in lead-exposed rats andpigs. The results of this study suggest that lead adverselyinfluences bone development through disruption of mineralizationduring growth.     

Baculovirus Expression of the Respiratory Syncytial Virus Fusion Protein using Trichoplusia ni Insect Cells

Respiratory syncytial virus (RSV) is a major viral pathogen responsible for severe respiratory tract infections in infants, young children, and the elderly. The RSV fusion (F) protein is highly conserved among RSV subgroups A and B and is the major protective immunogen. A genetically-engineered version of the RSV F protein was produced in insect cells using the baculovirus expression system. To express a secreted form of this protein, the transmembrane domain was eliminated by removing the region of the gene encoding 48 amino acids at the C-terminus. Production of the truncated RSV F protein (RSV-Fs) was compared in two different insect cell lines, Spodoptera frugiperda (Sf9) and Trichoplusia ni (High Five). The yield of RSV-Fs secreted from High Five insect cells was over 7-fold higher than that from Sf9 insect cells. Processing of the RSV-Fs protein was also different in the two insect cell lines. N-terminal sequencing demonstrated that while most of the RSV-Fs protein secreted by High Five cells was correctly processed at the F<$>_2<$>–F<$>_1<$> proteolytic cleavage site, most of the RSV-Fs protein secreted by Sf9 cells was unprocessed or incorrectly processed. Antigenicity of the major RSV F neutralization epitopes was maintained in the RSV-Fs protein secreted from High Five cells. The RSV-specific neutralizing antibody titres in the sera of cotton rats immunized with the RSV-Fs protein were equivalent to those in the sera of animals intranasally inoculated with live RSV. Animals immunized with either live RSV or the immunoaffinity purified RSV-Fs protein from High Five cells were completely protected against live virus challenge.     

Perioperative complications in children with pulmonary hypertension undergoing general anesthesia with ketamine

Background: Pulmonary arterial hypertension (PAH) is associated with significant perioperative risk for major complications in children, including pulmonary hypertensive crisis and cardiac arrest. Uncertainty remains about the safety of ketamine anesthesia in this patient population. Aim: Retrospectively review the medical records of children with PAH to ascertain the nature and frequency of peri‐procedural complications and to determine whether ketamine administration was associated with peri‐procedural complications. Methods: Children with PAH (mean pulmonary artery pressure ≥25 mmHg and pulmonary vascular resistance index ≥3 Wood units) who underwent general anesthesia for procedures during a 6‐year period (2002–2008) were enrolled. Details about the patient, PAH, procedure, anesthetic and postprocedural course were noted, including adverse events during or within 48 h of the procedure. Complication rates were reported per procedure. Association between ketamine and peri‐procedural complications was tested. Results: Sixty‐eight children (median age 7.3 year, median weight 22 kg) underwent 192 procedures. Severity of PAH was mild (23%), moderate (37%), and severe (40%). Procedures undertaken were major surgery (n = 20), minor surgery (n = 27), cardiac catheterization (n = 128) and nonsurgical procedures (n = 17). Ketamine was administered during 149 procedures. Twenty minor and nine major complications were noted. Incidence of cardiac arrest was 0.78% for cardiac catheterization procedures, 10% for major surgical procedures and 1.6% for all procedures. There was no procedure‐related mortality. Ketamine administration was not associated with increased complications. Conclusions: Ketamine appears to be a safe anesthetic option for children with PAH. We report rates for cardiopulmonary resuscitation and mortality that are more favorable than those previously reported.     

Subacute Toxicity of a Purine Nucleoside Phosphorylase Inhibitor in Rats

Rats received daily oral doses of 15, 50, 150, or 200 mg/kgCI-1000 for 4 weeks. Doses were selected based on findings froma 2-week range-finding study where doses of 250 and 500 mg/kgresulted in mortality. In the 4-week study, females given 200mg/kg were sacrificed during Week 2 due to poor condition. Serumcreatinine and urea nitrogen increased 2- to 2.5-fold in femalesgiven 200 mg/kg. Dose-related increases in urine volume, urinaryprotein excretion, and osmolar excretion occurred in both sexesbeginning at 50 mg/kg. Kidney weights increased 9–40%in both sexes at 50 mgkg; histopathologic changes were confinedto the 150 and 200 mg/kg groups. At Week 4, T-suppressor/cytotoxiclymphocytes were reduced 43% and T-helper/inducer lymphocyteswere reduced 22% in males given 200 mg/kg. In females, T-suppressor/cytotoxic lymphocytes were significantly decreased (approximately40%) at 50 and 150 mg/kg, with no significant effects on T-helper/inducerlymphocyte populations. At Week 8, following 4 weeks withouttreatment, T-lymphocyte subpopulations were similar in controland drug-treated groups. B-lymphocyte counts and percentageswere increased at Weeks 4 and 8 in males receiving 150 or 200mg/kg. Thymic weights decreased at Week 4 at doses of 150 and200 mg/kg. Plasma CI-1000 levels were higher in females thanin males at all doses except 15 mg/kg; C_max and AUC values werelargely dose proportional in both sexes. In summary, CI-1000was well-tolerated at doses of 15, 50, and 150 mg/ kg with noadverse effects occurring at 15 mg/kg. Drug-induced changesin the kidney were mild and reversible. Immunomodulatory effectswere noted at doses of 50 mg/kg or higher.