Double-helix coil for occlusion of large patent ductus arteriosus: evaluation in a chronic lamb model

Glyceraldehyde-3-phosphate dehydrogenase (G3PDH) is often used as a control gene for mRNA expression, however it has been proposed to be overexpressed in all hepatocellular carcinomas (HCC). Equal amounts of tumor and paired normal (T/N) RNA, based on OD260/280 nm, were compared using ethidium bromide staining, poly-T probing, gene-specific dot blot and Northern blots using control probes G3PDH, actin and histone H4. Using mRNA blots 13/20 surgical HCC pairs did not overexpress G3PDH. Those 7/20 intact samples which did appear to overexpress G3PDH on Northern blot could not be detected by poly-T probing of dot blots. The apparent overexpression was not specific for the control gene G3PDH nor for the malignancy HCC. It may represent partial mRNA degradation, or the presence of as yet unknown substances which interfere with absorption at 260/280 nm. We advise caution in selecting human T/N pairs for differential gene expression studies. For HCC, no clinicopathological variables, including cirrhosis, predicted whether a T/N sample pair was likely to be balanced or not.     

A re-examination of seasonal variation in suicides in Australia and New Zealand

BACKGROUND: To examine the seasonality of suicides in Australia and New Zealand during the period 1981 to 1993. METHODS: A chi-square test and a harmonic analysis were used to detect the seasonality of the suicide data. RESULTS: The reduced amplitude and a smaller proportion of variance accounted for by seasonality suggested the seasonal effect on suicide is greatly diminished. The absence of biseasonal distribution of female suicides was also consistently found in the two countries. The finding was contrary to the reported results in seventies in many Western countries. CONCLUSIONS: The change in living condition, roles of males and females and communication pattern resulted in the reduction of climatic and environment effect in the seasonality of suicides were suggested. LIMITATIONS: The results would be better if a longer series of suicide date were available.     

Cleavage motifs of the yeast 20S proteasome beta subunits deduced from digests of enolase 1

The 436-amino acid protein enolase 1 from yeast was degraded in vitro by purified wild-type and mutant yeast 20S proteasome particles. Analysis of the cleavage products at different times revealed a processive degradation mechanism and a length distribution of fragments ranging from 3 to 25 amino acids with an average length of 7 to 8 amino acids. Surprisingly, the average fragment length was very similar between wild-type and mutant 20S proteasomes with reduced numbers of active sites. This implies that the fragment length is not influenced by the distance between the active sites, as previously postulated. A detailed analysis of the cleavages also allowed the identification of certain amino acid characteristics in positions flanking the cleavage site that guide the selection of the P1 residues by the three active beta subunits. Because yeast and mammalian proteasomes are highly homologous, similar cleavage motifs might be used by mammalian proteasomes. Therefore, our data provide a basis for predicting proteasomal degradation products from which peptides are sampled by major histocompatibility complex class I molecules for presentation to cytotoxic T cells.     

Endothelin A-receptor blockade worsens endotoxin-induced hepatic microcirculatory changes and necrosis

BACKGROUND & AIMS: Endothelin 1 is considered to be an important regulator of sinusoidal blood flow and increases during endotoxemia. The purpose of this study was to investigate the role of endothelin 1 in hepatic microcirculation, oxygen transport, and liver injury during endotoxemia. METHODS: Male Sprague-Dawley rats were continuously infused with 2.5 mL/h of saline, 0.8 mg . kg-1 . h-1 of lipopolysaccharide (LPS), 3 mg . kg-1 . h-1 of BQ-485, an endothelin A-receptor antagonist, or LPS plus BQ-485 for 7 hours. RESULTS: BQ-485 infusion had no significant effect on hepatic microcirculation and liver injury. LPS increased the plasma levels of aspartate aminotransferase (AST) and total bilirubin and decreased the hepatic adenosine triphosphate (ATP) level and bile flow rate. LPS + BQ-485 infusion further increased the plasma levels of AST and total bilirubin and decreased the bile flow rate and the hepatic ATP level. Dual-spot microspectroscopy revealed mild decreases in sinusoidal erythrocyte velocity and oxygen transport in the LPS group and profound decreases in these parameters in the LPS + BQ-485 group. Histological examinations revealed massive necrotic changes in the pericentral regions of the LPS + BQ-485 group. CONCLUSIONS: These results suggest that blockade of endothelin A receptors disturbs hepatic microcirculation and oxygen transport and aggravates the necrotic injury induced by endotoxin.     

Conformation of xanthene dyes in the sulfhydryl 1 binding site of myosin. 2

The fluorescent dyes 5'-(iodoacetamido)tetramethylrhodamine (5'IATR) and 5'-(iodoacetamido)-fluorescein (5'IAF) bind covalently to the reactive sulfhydryl (SH1) of myosin subfragment 1 (S1), the 5'IATR as a dimer and the 5'IAF as a monomer. The conformation of the dimer and the dye-protein complex was investigated by comparison of several spectroscopic signals of the molecules before and after their association into a complex and interpretation of any changes using a coupled dipole oscillator model adapted for this problem [Burghardt & Ajtai (1995) Biophys. Chem. (submitted for publication)]. Absorption and fluorescence spectroscopies were performed on 5'IAF, 5'IATR, and rhodamine 6G (R6G) and rhodamine B (RB) as models of dimer conformation. Absorption, fluorescence, and circular dichroism (CD) spectroscopies were performed on 5'IATR-modified S1 (5'R-S1) and 5'IAF-modified S1 (5'F-S1). Combined spectroscopic and 2-D NMR data from rhodamines in solution determined the conformations of the dimers. Xanthene rings from dimers of identical dyes (homodimers) stacked in two structures having very different spectroscopic signatures. Xanthene rings from the heterodimer of R6G and RB stacked in one conformation. The two homodimer conformations of 5'IATR are equally likely to form in solution. The other rhodamine homodimers have one dominant, but not exclusive, structure. Both conformations of the 5'IATR dimer were coupled to a tryptophan as a model of the dye-protein interaction at SH1. The calculated CD from one dimer conformer (dimer A) coupled to tryptophan is negative for the lowest energy CD absorption band. The other dimer (dimer B) gives positive CD on the two lowest energy CD absorption bands. Both dimer structures of 5'IATR contributed to the early time-dependent CD signal from 5'IATR binding to SH1, but at equilibrium the CD signal indicated only dimer B, suggesting that the SH1 binding pocket converts dimer A into dimer B. The time-dependent CD signal from 5'IAF changes amplitude but not shape during the reaction with SH1. The model calculation accounting for the spectroscopic signals of 5'R-S1 and 5'F-S1 indicates several likely conformations of the 5'IATR dimer-tryptophan and 5'IAF-tryptophan complexes embedded in S1. These structures fit to the alpha-carbon structure of the SH1 binding pocket when the 5'IATR dimer and 5'IAF interact closely with Trp510 [Rayment et al. (1993) Science 261, 50-58].(ABSTRACT TRUNCATED AT 400 WORDS)     

Substrate specificity of human prolyl-4-hydroxylase

BACKGROUND: The mechanism responsible for the forward blood flow associated with external chest compression is still controversial. Evidence for both blood flow caused by direct cardiac compression and blood flow generated by a general increase in intrathoracic pressure has been found in experimental as well as clinical studies. No data are available concerning the mechanism causing forward blood flow in hypothermic patients undergoing cardiopulmonary resuscitation. Therefore, echocardiographic findings during external chest compression in seven hypothermic arrest victims are reported. METHODS: All transesophageal echocardiographic studies performed at the Anaesthesia department between 1994 and 1997 were reviewed and seven hypothermic patients with transesophageal echocardiography performed during cardiopulmonary resuscitation were identified. RESULTS: An open mitral valve or a circumferential reduction in aortic diameter during the compression phase was found in four of seven patients, indicating that primarily an increase in intrathoracic pressure (thoracic pump mechanism) generated forward blood flow. In three patients, mitral valve closure during external chest compression indicated that direct cardiac compression (cardiac pump mechanism) contributed to forward blood flow. Two patients studied during active compression-decompression cardiopulmonary resuscitation demonstrated enhanced right ventricular filling and aortic valve opening during active decompression of the thorax. CONCLUSIONS: In contrast to normothermic arrest victims, an open mitral valve during external chest compression is a common finding during hypothermia, indicating that thoracic pump mechanism is important for forward blood flow during cardiopulmonary resuscitation in hypothermic arrest victims. Aortic valve opening in two hypothermic arrest victims suggests forward blood flow also during active decompression of the thorax with the Cardiopump.     

Transit-time flow measurement for detection of early graft failure during myocardial revascularization

BACKGROUND: A low-flow situation in arterial and venous grafts has been associated with high rates of perioperative infarction and mortality. This study was designed to look at intraoperative graft flow and resistance in patients with coronary artery disease. METHODS: Coronary artery bypass graft flow was measured in 46 patients. Transit-time flow was used for coronary flow measurements at rest as well as after maximal vasodilation with adenosine infusion. RESULTS: Forty-three of the 46 patients showed normal internal mammary artery graft flow (>20 mL/min); 3 patients had no or minimal graft flow. Redoing the graft anastomosis in these 3 patients resulted in normalization of graft flow. The mean flow increased significantly after correction from 0.5 +/- 0.7 mL/min to 15.7 +/- 9.6 mL/min (p < 0.02). Conversely, vascular resistance decreased significantly from 138 +/- 10 to 4.8 +/- 1.8 Ohmv (p < 0.0001), as did the pulsatility index (from 146.9 +/- 95.7 to 3.4 +/- 1.8; p < 0.001). After correction, coronary flow reserve was 2.5 +/- 1.1. CONCLUSIONS: Measurements of intraoperative flow and resistance as well as derived variables allow assessment of early graft function and thus help prevent graft failure and reduce perioperative infarction. Transit-time volume flow might be a simple tool for quality control in coronary bypass procedures.     

Silicon analysis of breast and capsular tissue from patients with saline or silicone gel breast implants: II. Correlation with connective-tissue disease

The silicone breast implant controversy rages on. Recent work has demonstrated that normal or baseline breast tissue silicon levels in women who had had no prior exposure to any type of breast implant may be as high as 446 microg/gm of tissue. These data ranged from 4 to 446 microg/gm of tissue, with a median of 27.0 microg/gm of tissue. In addition, numerous other epidemiologic and rheumatologic studies have demonstrated no association between silicone breast implants and any connective-tissue diseases. Despite these reports, the use of silicone implants remains restricted. The present study measured breast and capsular tissue silicon levels from 23 breasts in 14 patients with saline implants, and from 42 breasts in 29 patients with silicone implants. No patient in the saline implant group presented with signs or symptoms of connective-tissue disease. Patients with silicone implants, however, were divided into three groups based on the presence or absence of signs or symptoms of connective-tissue disease: group I, no symptoms or signs; group II, + symptoms, no signs; and group III, + symptoms, + signs. Six patients in group III were diagnosed with a specific connective-tissue disease, including systemic lupus erythematosus, rheumatoid arthritis, or scleroderma. The most common indications for implant removal or exchange were capsular contracture and implant rupture, although 41 percent of patients with silicone implants expressed media-related concern over the implant issue. The most common symptoms described by patients in groups II and III were joint pain and stiffness, arm pain and numbness, and fatigue. In all groups, capsular tissue silicon levels were significantly greater than breast tissue levels. This finding may indicate that the capsule serves as a barrier to the distribution of silicone from the implant into adjacent breast tissue. Although breast tissue silicon levels in patients with silicone implants were not significantly greater than those in patients with saline implants (p = 0.48), capsular tissue levels in patients with silicone implants were, indeed, significantly greater than those in patients with saline implants (p < 0.001). However, no statistically significant differences in tissue silicon levels were observed with relation to the presence or absence of connective-tissue disease signs or symptoms in patients with silicone implants (groups I to III). Therefore, these data strengthen the conclusion that there is no association between tissue silicon levels and connective-tissue disease.