The role of myosin light chain kinase-dependent phosphorylation of myosin light chain in phorbol ester-induced contraction of rabbit aorta

We investigated the role of 20 kDa myosin light chain (MLC20) phosphorylation in contractions following protein kinase C (PKC) activation by 12-deoxyphorbol-13-isobutyrate (DPB) in rabbit aortae. DPB induced a sustained contraction and phosphorylation of MLC20 independent of a change in cytosolic Ca2+ ([Ca2+]i). Phosphorylation on Ser19 of MLC20, which is a target site of MLC kinase (MLCK), was 9.2 +/- 5.1% and 22.3 +/- 4.9% of the phosphorylation caused by KCl, at 5 and 30 min of application of DPB, respectively. When KCl-precontracted muscles were rinsed with Ca2+-free, EGTA solution, [Ca2+]i rapidly declined, MLC20 was dephosphorylated and the tension decreased. If DPB was present in the Ca2+-free solution, the relaxation and the dephosphorylation of either total MLC20 or Ser19 were inhibited. The phospholipase A2 inhibitor ONO-RS-082 partially antagonized the effects of DPB on the tension and the MLC20 dephosphorylation. In Ca2+-free solution, DPB induced a contraction smaller than that in normal solution without an increase in MLC20 phosphorylation, and the contraction was also sensitive to ONO-RS-082. These results suggest that a part of MLC20 phosphorylation following PKC activation is due to inhibition of MLC20 phosphatase and the phosphorylation is responsible for the contraction. Furthermore, a mechanism independent of [Ca2+]i and phosphorylation may play a significant role in the PKC-dependent contraction. The involvement arachidonic acid is suggested, not only in the inhibition of dephosphorylation but also in the Ca2+-independent regulation of contractile proteins.     

Evaluation of routine postoperative chest X-rays in the management of the cardiac surgical patient

OBJECTIVES: To evaluate the role of routine chest X-rays in the management of patients post cardiac surgery. METHODS: 340 adult patients undergoing cardiac surgery were studied in three consecutive groups (A, B, C) of 100 patients each. Forty patients were excluded due to the intensive care stay greater than 36 h (n = 35), or early mortality within 36 h (n = 5). Routine chest X-rays were performed according to different protocols in Groups A and B. In group C there were no routine chest X-rays during the entire postoperative period [corrected]. In all three groups chest X-rays were performed where clinically indicated. Group A had three routine chest X-rays post-operation. Group B had one routine chest X-ray on day 4 post-operation. Group C had chest X-rays only when indicated. The X-rays were evaluated in terms of their assistance value and the resultant number of interventions. RESULTS: The three groups were similar preoperatively for age, sex, preoperative left ventricular function, presence of chronic obstructive airway disease and type of operation performed. The total number of chest X-rays in groups A, B and C were 304, 133 and 36, respectively. The number of chest X-rays leading to interventions were five, four and four in groups A, B and C, respectively. Chest X-rays that helped in management were 36, 28, and 28, respectively, in the same groups. There was no mortality or morbidity attributable to non-performance of routine chest X-ray. CONCLUSIONS: Routine chest X-rays post-cardiac surgery are of very little value and patients are adequately managed by performing chest X-rays only when clinically indicated. There was no increased mortality or morbidity attributed to lack of routine chest X-rays in any of these groups. We recommend performing chest X-rays only when clinically indicated in satisfactorily recovering adult cardiac surgical patients.     

Modifications in high-density lipoprotein lipid composition and structure alter the plasma distribution of free and liposomal annamycin

Recent studies have shown that changes in lipoprotein cholesterol and triglyceride concentration alters the plasma distribution of free (Ann.) and liposomal annamycin (LAnn) and that the majority of Ann. is associated with high-density lipoproteins (HDL) following the incubation in plasma of LAnn. To demonstrate that alterations in HDL lipid composition and HDL structure may influence the plasma distribution of Ann. and LAnn, Ann. and LAnn (20 micrograms/mL) were incubated in plasma pretreated with dithionitrobenzoate (DTNB, a compound which inhibits the conversion of free cholesterol to esterified cholesterol) 18 h prior to the experiment or in untreated plasma for 60 min at 37 degrees C. In addition, Ann. and LAnn were co-incubated with DTNB in plasma for 60 min at 37 degrees C. Following incubation the plasma was separated into its HDL, low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), and lipoprotein-deficient plasma (LPDP) fractions by ultracentrifugation and assayed for Ann. by fluorimetry. The HDL plasma cholesterol:triglyceride concentration ratio was significantly decreased following 18 h of DTNB pretreatment compared to untreated plasma controls. No significant differences in LDL/VLDL plasma cholesterol:triglyceride concentration ratio following 18 h of DTNB pretreatment was observed. An increased number of discoidal HDL particles were observed following 18 h of DTNB pretreatment. When Ann. was incubated in plasma pretreated with DTNB for 18 h the percentage of Ann. recovered in the HDL, LDL, and VLDL fractions significantly increased. However, the percentage of Ann. recovered within the LPDP fraction was significantly decreased. When LAnn was incubated in plasma pretreated with DTNB for 18 h the percentage of Ann. recovered in the HDL fraction significantly decreased. The percentage of Ann. recovered in the LPDP fraction significantly increased when LAnn was incubated in plasma pretreated with DTNB for 18 h. No significant differences in Ann. lipoprotein distribution were observed when Ann. and LAnn were co-incubated with DTNB in plasma for 1 h. These findings suggest that the cholesterol:triglyceride concentration ratio and physical structure of HDL maybe important in defining the capacity of HDL to sequester Ann.     

Differential effects of DNA supercoiling on radical-mediated DNA strand breaks

Supercoiling is an important feature of DNA physiology in vivo. Given the possibility that the reaction of genotoxic molecules with DNA is affected by the alterations in DNA structure and dynamics that accompany superhelical tension, we have investigated the effect of torsional tension on DNA damage produced by five oxidizing agents: gamma-radiation, peroxynitrite, Fe2+/ EDTA/H2O2, Fe2+/H2O2, and Cu2+/H2O2. With positively supercoiled plasmid DNA prepared by a recently developed technique, we compared the quantity of strand breaks produced by the five agents in negatively and positively supercoiled pUC19. It was observed that strand breaks produced by gamma-radiation, peroxynitrite, and Fe2+/EDTA/H2O2 were insensitive to DNA superhelical tension. These results are consistent with a model in which chemicals that generate highly reactive intermediates (e.g., hydroxyl radical), but do not interact directly with DNA, will be relatively insensitive to the changes in DNA structure and dynamics caused by superhelical tension. In the case of Fe2+ and Cu2+, metals that bind to DNA, only Cu2+/H2O2 proved to be sensitive to DNA superhelical tension. Strand breaks produced by Cu2+/H2O2 in the positively supercoiled substrate occurred at lower Cu concentrations than in negatively supercoiled DNA. Furthermore, a sigmoidal Cu2+/H2O2 damage response was observed in the negatively supercoiled substrate but not in positively supercoiled DNA. The results with Cu2+ suggest that the redox activity, DNA binding orientation, or DNA binding affinity of Cu1+ or Cu2+ is sensitive to superhelical tension, while the results with the other oxidizing agents warrant further investigation into the role of supercoiling in base damage.     

Serotonin transporter gene-linked polymorphic region: allele distributions in relationship to body weight and in anorexia nervosa

Several lines of evidence implicate a role for the serotonergic system in body weight regulation and eating disorders. The magnitude and duration of postsynaptic responses to serotonin (5-HT) is directed by the transport into and release from the presynaptic neuron. Recently, a common polymorphism of a repetitive element in the region of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) was identified that results in a system of two common alleles. The activity of the 5-HTT, as measured in in vitro assays and in human lymphoblastoid cell lines, is dependent on the respective genotype. We thus hypothesized that this polymorphism is relevant for weight regulation in general and is possibly involved in the etiology of anorexia nervosa (AN). Allele frequencies and genotypes were determined in a total of 385 unrelated obese children, adolescents and adults, 112 underweight subjects and 96 patients with AN. Furthermore, both parents of 98 obese children and adolescents and of 55 patients with AN, respectively, were genotyped, thus allowing to test for both association and linkage. The comparison of allele frequencies between obese and underweight probands provided no evidence for a major role of the 5-HTTLPR in weight regulation. Patients with AN had allele frequencies not significantly different to those observed for obese and underweight individuals.     

Improved clinical echo-planar MRI using spatial-spectral excitation

The feline immunodeficiency virus (FIV) model of vertical human immunodeficiency virus type 1 transmission was used to explore the timing and tissue tropisms associated with intrauterine lentivirus infection. Cats chronically infected with FIV-B-2542 and their cesarean-derived fetuses and placentas were assayed by polymerase chain reaction and coculture at defined gestational intervals. Prevalence of fetal FIV infection was 0 at 3 weeks, 5% at 5 weeks, 38% at 7 weeks, and 60% at 9 weeks (term). Fetal tissues exhibiting the highest viral tropism were blood mononuclear cells and brain (each containing virus in 60% of FIV-positive fetuses) and thymus (47%). Maternal hematologic and virus load markers did not vary substantially with gestational stage. Therefore, fetal and/or placental maturation may determine the timing of lentivirus transmission. FIV infection prevalence in term fetuses was equivalent to that seen previously in vaginally delivered offspring, suggesting that most vertical FIV transmission occurs late in utero rather than intrapartum.     

Axillary vein puncture over the second rib

BACKGROUND: Video-assisted thoracic operations usually require single-lung ventilation under general anesthesia. However, for high-risk patients with other underlying pulmonary diseases, one has to consider risks of general anesthesia itself. METHODS: Four high-risk patients (4 men; mean age, 73 years) with intractable secondary pneumothorax and other underlying pulmonary diseases were treated by video-assisted thoracic operations under local and epidural anesthesia. Absorbable polyglycolic acid sheets and fibrin glue were used to control the air leakage. RESULTS: The mean duration of the procedure was 108 minutes. Pain and cough reflex were well controlled, and spontaneous breathing and hemodynamics were well maintained during the operation. The mean duration of the postoperative chest drainage was 5 days. No significant postoperative complication was encountered. No pneumothorax had recurred at a mean follow-up of 16 months. CONCLUSIONS: Video-assisted thoracic operations can be performed safely under local and epidural anesthesia for the treatment of intractable secondary pneumothorax in high-risk patients. The air leakage can be controlled with the use of polyglycolic acid sheets and fibrin glue without bullectomy.     

Predictive signs of discogenic lumbar pain on magnetic resonance imaging with discography correlation

STUDY DESIGN: The correlation between discogenic lumbar pain and disc morphology was investigated by using magnetic resonance imaging and discography. OBJECTIVES: To assess the various pathologic parameters seen on magnetic resonance imaging in patients with discogenic lumbar pain and to correlate them with observations on discography. SUMMARY OF BACKGROUND DATA: Although numerous previous studies on the subject have been performed, the correlations between various pathologic findings on magnetic resonance imaging and pain reproduction by provoked discography have not been explained fully. METHODS: One hundred and one lumbar discs in 39 patients were studied with magnetic resonance imaging and pain provocation discography. When pain reproduction under discography was concordant, various pathologic parameters on magnetic resonance imaging were analyzed by three statistical parameters to determine the associated magnetic resonance imaging findings. RESULTS: Radial tears commonly are demonstrated on magnetic resonance imaging in discs with concordant pain on discography. The presence of these tears is not a reliable predictor of a painful disc on discography. Although a high-intensity zone on T2-weighted images is a relatively reliable predictor of pain, the statistical values were lower than those in previous studies. Massive degeneration and severe disc height loss were rare in this population. These findings were good predictors of pain on disc injection. CONCLUSIONS: Although the lumbar intervertebral discs with posterior combined anular tears are likely to produce pain, the validity of these signs for predicting discogenic lumbar pain is limited.