Adverse effects of interrupting precordial compression during cardiopulmonary resuscitation

OBJECTIVES

In the current operation of automated external defibrillators, substantial time may be consumed for a "hands off" interval during which precordial compression is discontinued to allow for automated rhythm analyses before delivery of the electric countershock. The effects of such a pause on the outcomes of cardiopulmonary resuscitation were investigated.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

Research laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

Ventricular fibrillation was electrically induced in 25 Sprague-Dawley rats. After 4 mins of untreated ventricular fibrillation, precordial compression was begun and continued for 6 mins. Animals were then randomized to receive an immediate defibrillation shock or the defibrillation attempt was delayed for intervals of 10, 20, 30, or 40 secs.

MEASUREMENTS AND MAIN RESULTS

Immediate defibrillation restored spontaneous circulation in each instance. When defibrillation was delayed for 10 or 20 secs, spontaneous circulation was restored in three of five animals in each group. After a 30-sec delay, spontaneous circulation was restored in only one of five animals (p < .05). No animal was successfully resuscitated after a 40-sec delay (p < .01). With increasing delays, 24- and 48-hr survival rates were correspondingly reduced.

CONCLUSIONS

During resuscitation from ventricular fibrillation, prolongation of the interval between discontinuation of precordial compression and delivery of the first electric countershock substantially compromises the success of cardiac resuscitation. Accordingly, automated defibrillators are likely to be maximally effective if they are programmed to secure minimal "hands off" delay before delivery of the electric countershock.

[Clinical features of hemangioblastomas of the central nervous system]

OBJECTIVE

To study the clinical features of hemangioblastomas of the central nervous system (CNS).

METHODS

174 patients with hemangioblastomas of CNS were reviewed from 1982 to 1995. All patients were verified pathologically.

RESULTS

The tumors occurred mainly in patients between 21 and 40 years of age, and more often in men than in women. Most tumors were in the posterior fossa. CT scan of 119 patients showed that 95 hemangioblastomas appeared as cysts. Magnetic resonance imaging (MRI) for 47 patients showed that 32 had cysts. 49 patients were examined with angiography or DSA. 164 tumor mural nodules and solid masses were completely resected. The subtotal removal of others was performed. These patients received radiotherapy.

CONCLUSION

Enhanced MRI is the examination of choice for preoperative evaluation of cystic hemangioblastomas. Angiography or DSA is necessary in the diagnosis of bigger solid masses. The findings suggest that patients' age and degrees of section could affect the recurrence of hemangioblastoma.

[Determination of 5-fluorouracil in human serum by high performance liquid chromatography]

A reversed-phase HPLC method is described for determination of 5-fluorouracil in human serum. After being extracted with ethyl acetate 5-fluorouracil was analyzed by reversed-phase HPLC column (Zorbax ODS) and UV-detector (273nm) with tegaful as internal standard. The mobile phase was a mixture of methyl alcohol and water (20:80, V:V) at a flow rate of 1mL/min. The linear range was 0.04-50mg/L (r=0.9990) and the detectable limit was 10ng/mL. The average recovery was 96.85% and the coefficients of variation were 4.38% and 5.37% for within-day and day-to-day tests respectively.

Esophageal PCO2 as a monitor of perfusion failure during hemorrhagic shock

Measurement of gastric wall PCO2 (PgCO2) by tonometric method has emerged as an attractive option for estimating visceral perfusion during circulatory shock. However, gastric acid secretion obfuscates the tonometric measurement. We, therefore, investigated the option of measuring PCO2 in the esophagus to minimize these restraints. Hemorrhagic shock was induced in five Sprague-Dawley rats, and five rats served as sham controls. PgCO2 was measured with an ion-sensitive field effect transistor that was surgically implanted into the gastric wall. Esophageal luminal PCO2 (PeCO2) was measured by a second ion-sensitive field effect transistor sensor. During hemorrhagic shock, mean aortic pressure declined from 150 to 50 mmHg. Gastric blood flow decreased from 58 to 12 ml.min-1.100 g-1 (21% of preshock) and esophageal blood flow from 44 to 7 ml.min-1.100 g-1 (16% of preshock). PgCO2 simultaneously increased from 47 to 116 Torr and PeCO2 from 47 to 127 Torr. The increases in PgCO2 were highly correlated with increases in PeCO2 (r = 0.90). Esophageal tonometry may, therefore, serve as a practical alternative to gastric tonometry.

[A study on the counteracting effect of hypoxia and Qigong on simulated weightlessness and orthostatic tolerance after bedrest]

-6 degrees head down bed rest (-6 degrees HDBR) 21d were used to simulate weightlessness. 15 healthy males, aged 19-22, were divided into 3 groups with 5 people in each group: control group (-6 degrees HDBR), hypoxia group (-6 degrees HDBR + Low Oxygen), Qigong group (-6 degrees HDBR + Qigong). The results showed that the reduction of weight, perimeter of shank, daily average cardic output, basal cardic output and the pulse pressure of the Qigong group were lower than those of the control group (P<0.05). The basal cardic output and the perimeter of shank of the Hypoxia group reduced significantly than those of the control group (P<0.05). However, the reduction of the other physiological functions of the Hypoxia group were not significantly lower than that of the control group (P>0.05). During HUT +75 degrees 20 min orthostatic tolerance test after HDBR, the parameters in the Hypoxia group were better than those in the other groups. The average standing time was also longer, and no presyncopal symptom occured.

Buspirone, a serotonergic 5-HT1A agonist, is active in cerebellar ataxia. A new fact in favor of the serotonergic theory of ataxia

We have previously proposed a serotonergic hypothesis for cerebellar ataxia and mentioned that the levorotatory form of 5-hydroxytryptophan, a serotonin precursor, is partially active in subtypes of cerebellar ataxia, including cerebellar cortical atrophy (CCA). It has been demonstrated that 5-HT1A serotonergic receptors play an important role in the control of Purkinje cells discharges and in the inhibition of the release of glutamate by cerebellar glutamatergic terminals. To test further the serotonergic hypothesis of cerebellar ataxia, we administered buspirone, a 5-HT1A agonist usable in human medicine, in a randomized double blind drug placebo trial for 4 months. Nineteen patients with CCA were included; nine patients were given placebo and 10 Buspirone, at the mean dose of 0.69 mg/kg. The evaluation of ataxia was based on a static and a kinetic ataxia scale, fully quantitative measures and the evaluation of the sway path and area at posturography. At 4 months, a significant effect of buspirone was observed for drug induced gains of the kinetic score, two items of the static score, and the maximum duration of standing upright with feet together. These results indicate that a novel chemical therapeutic approach is possible for cerebellar ataxia; moreover, they support the existence of a link between cerebellar ataxia and disturbances of the serotonergic cerebellar system, especially a serotonergic deficit.

[Properties and applications of restricted access stationary phases]

Several types of restricted access stationary phases used for the analysis of drugs in biological fluids by direct injection into high-performance liquid chromatographic column are introduced in this paper with 20 references These new packings included internal surface reversed phase, semipermeable surface, shielded hydrophobic phase and mixed functional phase. The structural characteristics and the chromatographic properties of these packings are reviewed, especially with regard to their use in the assaying of drugs.

Alzheimer's PS-1 mutation perturbs calcium homeostasis and sensitizes PC12 cells to death induced by amyloid beta-peptide

Mutations in the presenilin-1 (PS-1) gene on chromosome 14 are linked to autosomal dominant early-onset Alzheimer's disease. The amino acid sequence of PS-1 predicts an integral membrane protein and immunocytochemical studies indicate that PS-1 is localized to endoplasmic reticulum (ER). We report that expression of PS-1 mutation L286V in cultured PC12 cells exaggerates Ca2+ responses to agonists (carbachol and bradykinin) that induce Ca2+ release from ER. Cells expressing L286V exhibit enhanced elevations of [Ca2+]i following exposure to amyloid beta-peptide (A beta) and increased vulnerability to A beta toxicity. An antagonist of voltage-dependent calcium channels (nifedipine), and a blocker of Ca2+ release from ER (dantrolene), counteract the adverse consequences of the PS-1 mutation. By perturbing Ca2+ homeostasis, PS-1 mutations may sensitize neurons to A beta-induced apoptosis.

Differential regulation of the two neuronal nitric-oxide synthase gene promoters by the Oct-2 transcription factor

The Oct-2 transcription factor has been shown previously to repress both the cellular tyrosine hydroxylase and the herpes simplex virus immediate-early genes in neuronal cells. Here we identify the gene encoding the neuronal nitric-oxide synthase (nNOS) as the first example of a gene activated in neuronal cells by Oct-2. The levels of the nNOS mRNA and protein are greatly reduced in neuronal cell lines in which Oct-2 levels have been reduced by an antisense method, although these cells have enhanced levels of tyrosine hydroxylase. Moreover, the nNOS gene regulatory region is activated by Oct-2 expression vectors upon cotransfection into both neuronal and non-neuronal cells, and this response is dependent upon a 20-amino acid region within the COOH-terminal activation domain of Oct-2. Of the two closely linked promoters that drive nNOS gene expression, only the downstream 5.1 promoter is activated by Oct-2, whereas the 5.2 promoter is unaffected. These effects are discussed in terms of the potential role of Oct-2 in regulating nNOS expression in the nervous system.

Human epithelial cystic fibrosis transmembrane conductance regulator without exon 5 maintains partial chloride channel function in intracellular membranes

The cardiac isoform of the cystic fibrosis transmembrane conductance regulator (CFTR) is a splice variant of the epithelial CFTR, with lacks 30 amino acids encoded by exon 5 in the first intracellular loop. For examination of the role of exon 5 in CFTR channel function, a CFTR deletion mutant, in which exon 5 was removed from the human epithelial CFTR, was constructed. The wild type and delta exon5 CFTR were expressed in a human embryonic kidney cell line (293 HEK). Fully mature glycosylated CFTR (approximately 170 kDa) was immunoprecipitated from cells transfected with wild type CFTR cDNA, whereas cells transfected with delta exon5 CFTR express only a core-glycosylated from (approximately 140 kDa). The Western blot test performed on subcellular membrane fractions showed that delta exon5 CFTR was located in the intracellular membranes. Neither incubation at lower temperature (26 degrees C) nor stimulation of 293 HEK cells with forskolin or CPT-cAMP caused improvement in glycosylation and processing of delta exon5 CFTR proteins, indicating that the human epithelial CFTR lacking exon5 did not process properly in 293 HEK cells. On incorporation of intracellular membrane vesicles containing the delta exon5 CFTR proteins into the lipid bilayer membrane, functional phosphorylation- and ATP-dependent chloride channels were identified. CFTR channels with an 8-pS full-conductance state were observed in 14% of the experiments. The channel had an average open probability (Po) of 0.098 +/- 0.022, significantly less than that of the wild type CFTR (Po = 0.318 +/- 0.028). More frequently, the delta exon5 CFTR formed chloride channels with lower conductance states of approximately 2-3 and approximately 4-6 pS. These subconductance states were also observed with wild type CFTR but to a much lesser extent. Average Po for the 2-3-pS subconductance state, estimated from the area under the curve on an amplitude histogram, was 0.461 +/- 0.194 for delta exon5 CFTR and 0.332 +/- 0.142 for wild type (p = 0.073). The data obtained indicate that deleting 30 amino acids from the first intracellular loop of CFTR affects both processing and function of the CFTR chloride channel.

Rectification of cystic fibrosis transmembrane conductance regulator chloride channel mediated by extracellular divalent cations

We report here distinct rectification of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel reconstituted in lipid bilayer membranes. Under the symmetrical ionic condition of 200 mM KCl (with 1 mM MgCl2 in cis intracellular and 0 MgCl2 in trans extracellular solutions, pH in both solutions buffered at 7.4 with 10 mM HEPES), the inward currents (intracellular-->extracellular chloride movement) through a single CFTR channel were approximately 20% larger than the outward currents. This inward rectification of the CFTR channel was mediated by extracellular divalent cations, as the linear current-voltage relationship of the channel could be restored through the addition of millimolar concentrations of MgCl2 or CaCl2 to the trans solution. The dose responses for [Mg]zero and [Ca]zero had half-dissociation constants of 152 +/- 72 microM and 172 +/- 40 microM, respectively. Changing the pH buffer from HEPES to N-tris-(hydroxymethyl)methyl-2-aminoethanesulfonic acid did not alter rectification of the CFTR channel. The nonlinear conductance property of the CFTR channel seemed to be due to negative surface charges on the CFTR protein, because in pure neutral phospholipid bilayers, clear rectification of the channel was also observed when the extracellular solution did not contain divalent cations. The CFTR protein contains clusters of negatively charged amino acids on several extracellular loops joining the transmembrane segments, which could constitute the putative binding sites for Ca and Mg.

An in vivo cytokine and endotoxin-independent pathway for induction of nitric oxide synthase II mRNA, enzyme, and nitrate/nitrite in alveolar macrophages

Dibutyryl cyclic AMP (DB-cAMP, 0.1 and 1.0 mg/kg) and the purine-2-receptor agonist methyl-thio-ATP (MT-ATP mg/kg) given by intratracheal (i.t.) administration to rats two hr before bronchoalveolar lavage (BAL) increased iNOS mRNA to be equal to or greater than that produced by i.t. LPS, without eliciting neutrophil infiltration into the alveolar space or the upregulation of tumor necrosis factor alpha (TNF alpha). Translation of DB-cAMP and MT-ATP stimulated iNOS mRNA into protein and activation of iNOS to produce RNI was slower than that resulting from LPS-stimulated iNOS mRNA. Diethyldithiocarbamate (5 mg/kg, i.t.) a sequestrant of reactive oxygen intermediates and an inhibitor of NFkappaB attenuated LPS-induced upregulation of iNOS mRNA without affecting that produced by DB-cAMP or MT-ATP. We conclude that an LPS and cytokine-independent pathway of transcription of iNOS mRNA exists in vivo, which can be directly activated by DB-cAMP and purine-2 receptor stimulation. It is possible that the increase in iNOS found in asthmatic patients and those with other diseases that are treated with drugs which affect the cAMP and purine systems may be iatrogenic rather than pathogenetic in origin.

Ethanol suppresses endotoxin but not platelet activating factor-induced hypotension and nitric oxide

Ethanol (ETOH) inhibits the immune response to endotoxemia. The early stage of endotoxin (LPS)-induced shock is associated with an acute phase cardiovascular depression (APCD). Release of platelet activating factor (PAF) and tumor necrosis factor alpha (TNF alpha) with upregulation of nitric oxide (NO) production may initiate the APCD. Since ETOH inhibits induction of NO synthase (iNOS) mNRA by LPS, we postulate that ETOH may mask the APCD associated with endotoxemia. To test this, Sprague-Dawley rats (280-320 g, n = 5-6/group) were given LPS [0.75 mg/kg, intravenously (i.v.)] or PAF (10 to 150 micrograms/kg, i.v.) 30 min after administration of sterile saline (PBS), BN-5073 a mixed PAF antagonist (0.50 microgram/kg, i.v.), or ETOH [2.2-5.5 g/kg, intraperitoneally (i.p.)]. Cardiovascular parameters and plasma concentrations of nitrate and nitrite (RNI), ETOH, TNF alpha, and neutrophil (PMN) generation of RNI were measured. LPS and PAF both produced APCD. LPS-induced APCD was associated with tachycardia, elevated plasma TNF alpha and RNI, and ex vivo generation of RNI by PMNs. ETOH and BN-50730 prevented LPS-induced APCD and increases in RNI and TNF alpha. ETOH, however, increased the mortality associated with APCD. PAF produced only hypotension, bradycardia and elevated plasma levels of TNF alpha. ETOH and LNMMA did not affect PAF-induced APCD. BN-50730 inhibited PAF-induced APCD and plasma TNF alpha. We conclude that 1) ETOH inhibits the APCD and induction of NO characteristic of endotoxemia and 2) ETOH-induced suppression of LPS-mediated APCD may be mediated in part by suppression of release of intracellular PAF. Ethanol may increase the morbidity and mortality of endotoxemia by masking the hypotension and humoral changes characteristic of early endotoxemia thereby delaying appropriate therapy and by diminution of the protective effects of endogenous NO.

Comparative effects of chelating agents on pulmonary toxicity of systemic nickel in mice

N-Benzyl-D-glucaminedithiocarbamate (BGD), diethyldithiocarbamate (DDTC), dihydroxyethyldithiocarbamate (DHED), trans-1,2-cyclohexanediamine N,N,N',N'-tetraacetic acid (CDTA) and meso-2,3-dimercaptosuccinic acid (DMSA) were studied for their protective effects against the pulmonary toxicity in mice induced by acute exposure to nickel. Nickel injection increased lipid peroxidation, lactate dehydrogenase (LDH) activity and the concentrations of protein, phospholipids (PL) and essential metals such as Ca, Fe and Zn and decreased the reduced glutathione (GSH) concentration and alkaline phosphatase (ALP) activity in the lungs. At 30 min after Ni treatment, DMSA, BGD and DDTC effectively depressed Ni concentration in the lungs. At 24 h after Ni treatment, DMSA and BGD were effective in mobilizing Ni from the lungs. Both DMSA and BGD significantly prevented increases in lipid peroxidation and in the concentrations of PL, Ca, Fe and Zn, and decreases in GSH concentration and ALP activity in the lungs of mice caused by Ni injection. Treatment with DMSA or BGD was more effective than that with other chelating agents in decreasing the pulmonary Ni concentration and preventing other changes caused by acute exposure to Ni, resulting in effective protection against Ni-induced pulmonary damage.

Human homolog of patched, a candidate gene for the basal cell nevus syndrome

The basal cell nevus syndrome (BCNS) is characterized by developmental abnormalities and by the postnatal occurrence of cancers, especially basal cell carcinomas (BCCs), the most common human cancer. Heritable mutations in BCNS patients and a somatic mutation in a sporadic BCC were identified in a human homolog of the Drosophila patched (ptc) gene. The ptc gene encodes a transmembrane protein that in Drosophila acts in opposition to the Hedgehog signaling protein, controlling cell fates, patterning, and growth in numerous tissues. The human PTC gene appears to be crucial for proper embryonic development and for tumor suppression.

Participation of the yeast activator Abf1 in meiosis-specific expression of the HOP1 gene

The meiosis-specific gene HOP1, which encodes a component of the synaptonemal complex, is controlled through two regulatory elements, UASH and URS1H. Sites similar to URS1H have been identified in the promoter region of virtually every early meiosis-specific gene, as well as in many promoters of nonmeiotic genes, and it has been shown that the proteins that bind to this site function to regulate meiotic and nonmeiotic transcription. Sites similar to the UASH site have been found in a number of meiotic and nonmeiotic genes as well. Since it has been shown that UASH functions as an activator site in vegetative haploid cells, it seemed likely that the factors binding to this site regulate both meiotic and nonmeiotic transcription. We purified the factor binding to the UASH element of the HOP1 promoter. Sequence analysis identified the protein as Abf1 (autonomously replicating sequence-binding factor 1), a multifunctional protein involved in DNA replication, silencing, and transcriptional regulation. We show by mutational analysis of the UASH site, that positions outside of the proposed UASH consensus sequence (TNTGN[A/T]GT) are required for DNA binding in vitro and transcriptional activation in vivo. A new UASH consensus sequence derived from this mutational analysis closely matches a consensus Abf1 binding site. We also show that an Abf1 site from a nonmeiotic gene can replace the function of the UASH site in the HOP1 promoter. Taken together, these results show that Abf1 functions to regulate meiotic gene expression.

Open trial of intravenous tissue plasminogen activator in acute carotid territory stroke. Correlations of outcome with clinical and radiological data

BACKGROUND AND PURPOSE

Pilot studies using early thrombolytic therapy in stroke have suggested that recombinant tissue plasminogen activator (rTPA) might be effective. While large, double-blind, randomized studies are needed, open trials could generate hypotheses concerning (1) the clinical correlations of outcome, (2) the significance of CT scan data during the first week, and (3) the use of adjunctive therapies.

METHODS

We performed an open trial of intravenous rTPA on patients referred to our emergency service with all types of ischemic stroke in the carotid territory. All patients between 20 and 81 years hospitalized during 1994 with completed stroke in the internal carotid artery territory and a baseline Scandinavian Stroke Scale score lower than 48, even with severe disturbances of consciousness, were included. The inclusion time was within 7 hours after stroke onset. A 0.8-mg/kg dose of rTPA was infused for 90 minutes. Intravenous heparin was given either immediately at efficient dosage or after 24 hours. Mannitol was used in patients with severe presentation. The Scandinavian Stroke Scale evaluation was done at baseline, 3 hours, and 1, 7, 30, and 90 days. The CT scan was performed before the treatment and at days 1 (24 +/- 6 hours) and 7.

RESULTS

Forty-three consecutive patients met the criteria of the protocol. The mean age at inclusion was 65 +/- 10.4 years, and the mean interval to treatment was 232 +/- 79 minutes. At day 90, 25 patients (58.1%) exhibited a complete regression of symptoms, and 3 had moderate neurological sequelae. Thirteen patients had severe neurological sequelae, 11 with infarcts and 2 with secondary parenchymal hematomas. Two patients died (4.6%), 1 with hematoma. The overall hematoma rate was 6.9%. Excellent outcome at day 90 was significantly correlated with major neurological improvement at day 1. Intravenous immediate heparin versus delayed heparin after 24 hours improved the ischemic outcome but not the overall outcome. Reinfarction syndromes after major neurological improvement, likely to be rethrombosis syndromes, were observed in 3 patients (6.9%). For the day 1 CT scan, poor outcome was associated with the presence of structured and homogeneous hypodensities likely to represent classic infarcts, as confirmed by day 7 CT scan. Conversely, total recovery was significantly associated with the absence of any image or with unstructured hypodensities, a particular type of image characterized by its heterogeneous darkness and often polylobar shape. This type of image disappeared at day 7 in 17.6% of the cases and is likely to represent reperfusion images and/or incomplete ischemic damage.

CONCLUSIONS

The results obtained in this open, small study suggest safety and effectiveness of rTPA thrombolysis at the dose of 0.8 mg/kg within 7 hours in acute strokes of the carotid territory, including highly serious baseline neurological presentations, until age 81 years and under special therapeutic conditions. Complete recovery is significantly associated with major neurological improvement during the first 24 hours and the presence of a particular type of image at day 1 CT scan characterized by an unstructured hypodensity, often polylobar and heterogeneous, which is likely to correspond to reperfusion images.

Phosphorylation-dependent block of cystic fibrosis transmembrane conductance regulator chloride channel by exogenous R domain protein

The cystic fibrosis transmembrane conductance regulator (CFTR) constitutes a linear conductance chloride channel, which is regulated by cAMP-dependent protein kinase phosphorylation at multiple sites located in the intracellular regulatory (R) domain. Studies in a lipid bilayer system, reported here, provide evidence for the control of CFTR chloride channel by its R domain. The exogenous R domain protein (encoded by exon 13 plus 85 base pairs of exon 14) interacted specifically with the CFTR molecule and inhibited the chloride conductance in a phosphorylation-dependent manner. Only the unphosphorylated R domain protein blocked the CFTR channel. Such functional interaction suggests that the putative gating particle of the CFTR chloride channel resides in the R domain.

[Interaction of human serum albumin with berberine hydrochloride by fluorescence method]

Fluorescence method has been used to observe the fluorescence quenching of human serum albumin (HSA) by its interaction with berberine hydrochloride (BH). The interaction dissociation constants of HSA and BH have been determined from a double reciprocal Lineweaver-Burk plot (Kd = 1.73 x 10(5) mol/L).

Bond strength of composite to sound and artificial carious dentin

PURPOSE

To determine the in vitro bond strength of a composite (Herculite XRV) to sound dentin and artificial carious lesions in dentin.

MATERIALS AND METHODS

Buccal and lingual surfaces from extracted human molar teeth were ground to expose sound dentin surfaces. The buccal surface was maintained as sound dentin, while an artificial carious lesion was created in the lingual surface using an acidified gelatin gel. A bonding agent (Optibond) was applied to both buccal and lingual surfaces with and without prior etching with 37.5% phosphoric acid. The composite was applied and debonded under tension after 24 hours in water at 37 degrees C.

RESULTS

Both sound dentin (23.1 MPa) and etched sound dentin (22.2 MPa) had similar bond strengths, whereas artificial carious lesions in dentin that had been etched (11.8 MPa) and non-etched dentin lesions (8.8 MPa) had significantly lower bond strengths. Adhesive failures were greatest for dentin lesions (60-95%) and least for sound dentin(40-50%). Etching with phosphoric acid did not improve the bond strength of composite to sound dentin or artificial carious lesions in dentin.