Inhibitory effects of nitric oxide and interleukin-10 on production of tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 in mouse alveolar macrophages

AIM

To observe the effects of nitric oxide and interleukin-10 (IL-10) on inflammatory reaction in mouse alveolar macrophages (AM).

METHODS

AM from mice were stimulated by lipopolysaccharides (LPS) 10 mg.L-1 and nitric-oxide synthase inhibitor, S-methylisothiorea sulfate (SMT) or nitric-oxide donor, S-nitroso-N-acetyl-D, L-penicillamine (SNAP). The production of tumor necrosis factor alpha (TNF alpha), IL-1 beta, IL-6, and IL-10 by AM were measured by ELISA.

RESULTS

After LPS-stimulation, TNF alpha, IL-1 beta, and IL-6 peaked at 6, 12, and 24 h, respectively by AM. SMT inhibited LPS-induced nitric oxide release and increased IL-1 beta and IL-6 secretions in AM, but the TNF alpha levels remained unchanged. SNAP had inhibitory effects on IL-1 beta and IL-6 secretions in a concentration-dependent manner, but exerted no effect on TNF alpha release. TNF alpha, IL-1 beta, and IL-6 secretions were inhibited by recombinant IL-10, but the cytokines release was upregulated by anti-IL-10 monoclonal antibody.

CONCLUSION

Both endogenous and exogenous nitric oxide and IL-10 had inhibitory effects on the LPS-induced TNF alpha, IL-1 beta, and IL-6 secretions in mouse AM.

Pathfinding by identified zebrafish motoneurons in the absence of muscle pioneers

To identify the cellular cues that guide zebrafish neuronal growth cones to their targets, we examined interactions between identified motor growth cones and identified muscle fibers and tested whether these fibers were required for growth cone navigation. Caudal primary motoneurons (CaPs) and middle primary motoneurons (MiPs) are identified motoneurons that innervate cell-specific regions of the myotome. Growth cones of both cells initially extend along a common pathway and then pause at a set of identified muscle fibers, called muscle pioneers, before diverging along cell-specific pathways. Muscle pioneers are intermediate targets of both CaP and MiP (Westerfield et al., 1986; Liu and Westerfield, 1990); both motoneurons extend their growth cones directly to the muscle pioneers on which the first functional neuromuscular contacts form, suggesting that muscle pioneers may provide guidance information to these growth cones. We tested this idea by ablating muscle pioneers and observing the resulting motor axonal trajectories. Both CaP and MiP ultimately formed normal axonal arbors after muscle pioneer ablation, showing that muscle pioneers are unnecessary for formation of correct axonal trajectories; however, although final cellular morphology was correct in the absence of muscle pioneers, MiP growth cones branched abnormally or extended ventrally beyond the common pathway. Ablation of CaP and the muscle pioneers together increased the aberrant behavior of the MiP growth cone. Our results provide evidence that an intermediate target, the muscle pioneers, affects motor axonal extension without altering target choice, suggesting that other cues also contribute to proper pathway navigation.

Home-made endoloops for bullous lung disease: a case report

Various surgical techniques for bulla ablation have been used since the introduction of video-assisted thoracoscopic surgery. Endoscopic stapler resecting (Endo-GIA) is now the most common procedure for bulla ablation. Other endoscopic techniques include bulla suturing, clipping, laser ablation and electrocauterization. We present here a select report on using a "home-made" endoloop on a patient with bullous lung disease. No intraoperative morbidity was attributable to the procedure. The operating room time was 110 minutes, and ventilator support was given for 18 hours. The chest tube was removed on day 7 and the patient discharged on the ninth postoperative day uneventfully. The patient exhibited subjective improvement in his symptom preceptions during an one-month follow-up examination. A comparison of pre- and post operative functional evaluation showed increase in FEV1 (from 0.45 L to 1.02 L) during 3-month follow-up. From our experience, thoracoscopic home-made endoloop ligation is a safe and cost effective means of volume reduction surgery for bullous emphysema that interferes with optimum function of the adjacent lung parenchyma.

Video-assisted thoracic surgery in treatment of chest trauma

Although the indications for video-assisted thoracic surgery (VATS) have expanded rapidly, especially in the areas of therapeutic and operative procedures, its role in the definite surgical treatment of chest trauma is not clear. From July 1994 to December 1995, 56 patients with hemothorax or posthemothorax complications resulting from chest trauma received thoracic surgery. Their ages ranged from 17 to 71 years. Mechanisms of injury included penetrating (n = 23) and blunt injury (n = 33). VATS was successfully applied in 50 patients; six patients with cardiovascular injuries (n = 4) or minor chest wall lacerations (n = 2) did not receive VATS. All patients who received VATS survived, with no morbidity. Twelve of the 50 patients treated with VATS would have otherwise had to undergo thoracotomy. Our results indicate that VATS can be safely used in hemodynamically stable patients with no cardiovascular or great vessel injury, sparing many patients the pain and morbidity associated with thoracotomy. Additionally, use of VATS may reduce the likelihood of posthemothorax complications by allowing early direct inspection of the chest wall, because VATS has a lower associated risk and can be performed with a lower index of suspicion than can standard thoracotomy.

The nucleotide sequence and predicted secondary structure of small subunit (18S) ribosomal RNA from Spirometra erinaceieuropaei

The nucleotide (nt) sequence of a small subunit (18S) ribosomal RNA gene from the plerocercoid of Spirometra erinaceieuropaei (SEP) was determined. The gene with 2182 bp in length is larger than that of most eukaryotes. Extra nt sequences occur in regions known to be variable (V4 and V7). The predicted secondary structure of the nt positions 679-933 (V4) revealed different helices from that of other eukaryotes. The region between nt positions 1540 and 1749 (V7) was different from that of other eukaryotes, but the secondary structure prediction by computer analysis demonstrated that this part of 18S rRNA sequence from S. erinaceieuropaei may form a single extended helix. Nt that were aligned with those of nine other parasites were used to estimate phylogenetic relationships. The data presented here clearly indicate that S. erinaceieuropaei is closely related to Echinococcus granulosus.

Prolonged circulatory arrest in moderate hypothermia with retrograde cerebral perfusion. Is brain ischemic?

BACKGROUND

Circulatory arrest (CA), which provides a bloodless field and good visualization without the need of aortic cross-clamp, is commonly used to facilitate repair of aortic lesions. However, extended periods of CA may impair cerebral metabolism and cause ischemic injury. Studies were performed to evaluate the efficacy of retrograde cerebral perfusion (RCP) in protecting the brain from ischemic injury during a prolonged period of CA in moderate hypothermia.

METHODS AND RESULTS

Twenty-three patients (18 men and 5 women) were operated on for aortic lesions (17 acute type A aortic dissection and 6 chronic type A aortic dissection with Marfan's syndrome). The aortic operations were performed with CA (58 to 104 minutes; mean +/- SD, 75 +/- 12 minutes) at a rectal temperature of 23.3 +/- 0.5 degrees C (21 degrees C to 25 degrees C). For RCP, cold (14 degrees C to 18 degrees C) oxygenated blood (300 mL/min) was pumped to the superior vena cava with internal jugular venous pressure of 15 +/- 5 mm Hg. The cardiopulmonary bypass time was 157 +/- 18 minutes. Cortical blood flow during RCP detected by subdural laser Doppler probe was 10 +/- 5% of baseline. Percent oxygen extraction and pyruvate and lactate levels (26 +/- 2% and 0.43 +/- 0.17 and 45 +/- 16 mg/dI) were insignificantly different from those before CA (28 +/- 3% and 0.71 +/- 0.08 and 62 +/- 20 mg/dL, P > .05). Creatine kinase-BB isoenzyme was undetectable. All but 1 patient survived the operation (95.5%) and woke up without neurological deficit. Follow-up (mean, 13 months) was complete in all survivors. There were no late deaths. Cerebral functional studies performed 3 months after discharge showed results insignificantly different from those of the normal control subjects.

CONCLUSIONS

There is no evidence of ischemia of the brain during prolonged moderate hypothermic CA with the aid of RCP. Retrograde cerebral perfusion effectively extends the safe time of CA. Deep hypothermia during CA seems unnecessary.

Molecular cloning and expression of the gene encoding a cysteine proteinase of Spirometra erinacei

A cDNA library constructed from plerocercoid of Spirometra erinacei (SEP) was immunoscreened using rabbit anti-plerocercoid proteinase polyclonal antibody. A 1.0-kb cDNA clone encoding a cysteine proteinase composed of 336 amino acids was isolated. The amino acid sequence predicted from the cDNA showed significant homology with human and mouse cathepsin L. N-terminal amino acid sequence of the native cysteine proteinase extracted from SEP was the same as that of mature proteinase predicted from the cloned gene. The gene encoding the proteinase was characterized by Southern and Northern blot analysis using the cDNA as a probe. The proteinase with a molecular mass of 34 kDa was demonstrated in in vitro translation products using anti-proteinase polyclonal antibody. A fusion protein derived from the cDNA synthesized by Escherichia coli (TB1) using the expression vector, pMAL-c2 was identified as an immunodominant antigen by epitope-selection method and had no cross-reactivity with other parasite-infected sera. A genomic DNA library derived from SEP was screened by the colony hybridization technique using the cDNA probe. A gene with 4.5 kb encoding the proteinase was obtained, which comprised three exons and two introns.

Genes that control a temperature-compensated ultradian clock in Caenorhabditis elegans

Substantial progress has been made in understanding the genetic basis of temperature-compensated circadian clocks. Ultradian rhythms, with a period shorter than 24 h, are at least as widespread as circadian rhythms. We have initiated genetic analysis of defecation behavior, which is controlled by an ultradian clock in Caenorhabditis elegans. The defecation motor program is activated every 45 sec, and this rhythm is temperature compensated. We describe mutations in 12 genes that either shorten or lengthen the cycle period. We find that most of these mutations also disrupt temperature compensation, suggesting that this process is an integral part of the clock. These genes open the way for molecular genetic dissection of this ultradian clock.

Gigahertz planar photoconducting antenna activated by picosecond optical pulses

We have generated 1-20-GHz microwave pulses by illuminating an Fe-compensated InP wafer with 50-ps optical pulses at normal incidence. The process of the generation of microwave radiation was monitored and analyzed directly through a 40-GHz sampling oscilloscope with precision. The saturation properties, the waveform evolution, and the optical coupling efficiency of the gigahertz photoconducting antenna are discussed. The flexibility, compactness, and high-resolution features offered by this technique merit new applications for radar communication as well as for other microwave detecting devices.

Preparation and characterization of cyclopolymerizable resin formulations

An amine-catalyzed reaction between acrylates and formaldehyde has been used to convert mono-acrylates to difunctional monomers and di-acrylates to multifunctional oligomers by linking the acrylic double bonds together in 1,6-diene pairs. The resulting monomers and oligomers undergo efficient cyclopolymerization to high conversion with significantly less shrinkage than normally found for acrylates. In this study, a convenient single-step process was used with mixtures of mono- and di-acrylate starting materials to produce a series of resins with potential for effective cyclopolymerization. Incremental changes in the ethyl acrylate (EA) to ethoxylated bisphenol A diacrylate (EBPAD) ratio directly supplied cyclopolymerizable resins with a broad range of viscosities and product distributions. Those resins produced from reaction mixtures rich in EA have low viscosities because of high diluent monomer contents and limited oligomerization of EBPAD due to end-cap formation. Resin viscosity and average molecular weight of the oligomeric component of the resin were inversely related to the amount of EA used in the reaction. Through the choice of reactants and their ratio, this simple technique has the potential to provide cyclopolymerizable resins for use in a variety of dental polymer applications.

Characteristics of the delayed rectifier current (IKr and IKs) in canine ventricular epicardial, midmyocardial, and endocardial myocytes. A weaker IKs contributes to the longer action potential of the M cell

Recent studies have described regional differences in the electrophysiology and pharmacology of ventricular myocardium in canine, feline, rat, guinea pig, and human hearts. In this study, we use standard microelectrode and whole-cell patch-clamp techniques to examine the characteristics of the action potential and the delayed rectifier K+ current (IK) in epicardial, M region (deep subepicardial to midmyocardial), and endocardial cells isolated from the canine left ventricle. Cells from the M region displayed much longer action potential durations (APDs) at slow rates. At a basic cycle length of 4 s, APD measured at 90% repolarization was 358 +/- 16 (mean +/- SEM), 262 +/- 12, and 287 +/- 11 ms in cells from the M region, epicardium, and endocardium, respectively. Steady state APD-rate relations were steeper in cells from the M region. In complete Tyrode's solution, IK was smaller in myocytes from the M region when compared with those isolated from the epicardium or endocardium. Further characterization of IK was conducted in a Na(+)-, K(+)-, and Ca(2+)-free bath solution to isolate the slowly activating component of the delayed rectifier (IKs) from the rapidly activating component (IKr). IKs was significantly smaller in M cells than in epicardial and endocardial cells. With repolarization to -20 mV, IKs tail current density was 1.99 +/- 0.30 pA/pF (mean +/- SEM) in epicardial cells, 1.83 +/- 0.18 pA/pF in endocardial cells, and 0.92 +/- 0.14 pA/pF in M cells. Voltage dependence and time course of activation and deactivation of IKs were similar in the three cell types. The relative contribution of IKr and IKs among the three cell types was examined by using 6 mmol/L [K+]o Tyrode's solution with and without E-4031, a highly selective blocker of IKr. An E-4031-sensitive current was observed in the presence but not in the absence of extracellular K+. This rapidly activating component showed characteristics similar to those of IKr as described in rabbit and cat ventricular cells. Deactivation of IKr was significantly slower than that of IKs. IKr (E-4031-sensitive component) tail current density was similar in the three cell types, whereas IKs (E-4031-insensitive component) tail current density was significantly smaller in the M cells. Our results suggest that the distinctive phase-3 repolarization features of M cells are due in part to a lesser contribution of IKs and that this distinction may also explain why M cells are the main targets for agents that prolong APD in ventricular myocardium.(ABSTRACT TRUNCATED AT 400 WORDS)

Protection of the brain by retrograde cerebral perfusion during circulatory arrest

Hypothermic circulatory arrest is commonly used to facilitate repair of complex congenital heart defects and aortic lesions and for complex neurosurgical procedures. However, extended periods of circulatory arrest may impair cerebral metabolism and cause ischemic injury. Retrograde cerebral perfusion has been applied recently in aortic surgery to protect the brain. From January 1991 to December 1993, 29 patients underwent emergency operations to repair acute type A aortic dissection with the aid of hypothermic circulatory arrest. Six patients received hypothermic circulatory arrest without retrograde cerebral perfusion with a rectal temperature of 16.4 degrees +/- 0.9 degrees C (mean +/- standard error of the mean, group 1). Retrograde cerebral perfusion during hypothermic circulatory arrest was performed in 15 patients with a rectal temperature of 15.9 degrees +/- 0.5 degrees C (group 2) and in eight patients with a rectal temperature of 21.7 degrees +/- 0.8 degrees C (group 3). The hypothermic circulatory arrest times were 25 +/- 4, 42 +/- 4, and 63 +/- 6 minutes, respectively (p < 0.05). The cardiopulmonary bypass times were 173 +/- 5, 184 +/- 7, and 143 +/- 6 minutes, respectively (p < 0.05). All patients survived the operation and regained consciousness with no neurologic defects. Follow-up (mean 23.2, 14.5, and 5.1 months, respectively) was complete in all patients except one. This patient, from group 2, was killed in a road traffic accident 12 months after the operation. Our experience suggests that retrograde cerebral perfusion can effectively protect the brain from ischemic injury and extend the safe period of hypothermic circulatory arrest. With the aid of retrograde cerebral perfusion, prolonged circulatory arrest can probably be performed safely with moderate hypothermia.

Surgical treatment of acute type A aortic dissection with an intraluminal sutureless graft

The surgical treatment of acute type A aortic dissection remains a great challenge to all cardiac surgeons. From January 1991 to June 1993, 21 consecutive patients (13 men and eight women, aged 34 to 74 years) underwent emergency operations to repair acute type A aortic dissection, with the aid of hypothermic circulatory arrest. The intima tear was located in the ascending aorta in 13 patients, in the aortic arch in five patients, and in the descending aorta in three patients. The dissected ascending aorta was replaced with sutureless, intraluminal vascular grafts in all 21 patients. The intima tears in the aortic arch of five patients were primarily repaired. Modified Cabrol's shunts were created in seven patients for hemostasis, and Dacron grafts were used to wrap the ascending aorta in 18 patients. Retrograde cerebral perfusion during circulatory arrest was performed on 15 patients. The circulatory arrest time was 37 +/- 10 minutes (mean +/- SD). All patients survived the operation and regained consciousness in the early postoperative period without neurologic deficit. Post-treatment follow-ups (mean, 18.2 months) were completed in all patients except one, who died 12 months after the operation as a result of a traffic accident. All of the surviving patients are doing well without any further aortic operations. Our experience suggests that surgical repair of the acute type A aortic dissection can be a simple and safe procedure if sutureless intraluminal grafts are used and hypothermic circulatory arrest and retrograde cerebral perfusion are utilized.

Regulation of a periodic motor program in C. elegans

A three-part motor program mediates a defecation every 45 sec in well-fed wild-type Caenorhabditis elegans. Individual worms maintain this 45 sec rhythm with an SD of about 3 sec. We present evidence that the defecation cycle is controlled by an endogenous clock, most likely a neuronal pattern generator. The phase of the behavioral rhythm can be reset like pattern generators in other animals. The rhythm was reset by stimulating a well-characterized neuronal circuit mediating response to light touch. Also, animals that spontaneously stopped feeding interrupted their defecation rhythms. When they resumed feeding these animals reactivated the motor program in phase with the previously established rhythm, indicating that an endogenous clock continues to run even when the behavior is not expressed. Control of the defecation rhythm is independent of expression of the motor program. Most previously isolated mutations that affect the motor program (Thomas, 1990) do not alter the rhythm of the behavior; the motor steps themselves are defective but not the timing of their activation. Laser kills of identified motor neurons that affect particular parts of the motor program also did not change the defecation rhythm. Another sensory stimulus, food, strongly modulates defecation behavior: animals away from food rarely activated the motor program, and food dilution resulted in a graded lengthening of the cycle period. To elucidate further the relationship between feeding and defecation rhythms we studied a mutation, dec-8(sa200), that caused worms to continue to activate the motor program in the absence of food. The mutant did not require the presence of food to activate the motor program, although food made the rhythm more precise. In the presence of food, dec-8(sa200) animals exhibited tandem activations of the defecation motor program; the principal activation was followed by a more variable second activation. Further experiments suggested that the tandem activations of the motor program are not due to the activity of multiple oscillators.

Treatment of acute type A aortic dissection with intraluminal sutureless prosthesis

Sutureless intraluminal aortic graft has been used for substitution of aorta, with the advantages of decreasing the aortic cross-clamp time and decreased blood loss. From January 1991 to December 1992, 10 consecutive patients underwent emergency operations to repair acute type A aortic dissection in which sutureless intraluminal grafts were used for replacement of ascending aorta. There were 5 men and 5 women, with ages that ranged from 40 to 74 years (mean, 51 years). The inclusion method was used in all patients. Modified Cabrol shunts were created in 7 patients. Dacron graft (Meadox Medicals, Inc, Oakland, NJ) was used to wrap the ascending aorta in 7 patients. The circulatory arrest time was 33 +/- 13 (mean +/- standard deviation) minutes, and the cardiac ischemic time was 64 +/- 17 minutes. Retrograde superior vena cava cerebral perfusion during circulatory arrest was performed on 4 patients. All patients survived. One patient had a minor stroke and pneumonia with complete recovery. There was no evidence of pseudoaneurysm formation, graft erosion, graft migration, or aortic bleeding in the postoperative period. No patients had permanent renal deficit. Follow-up (1 to 22 months; mean, 9.6 months) of all patients revealed satisfactory graft function, with no device-related deaths and no known complications attributable to the prosthesis, such as thrombosis, erosion, pseudoaneurysm formation, or hemorrhage. Our experience suggests that grafting of the ascending aorta is less hazardous with the sutureless grafts than with the conventional sutured anastomosis technique. We are now using this method whenever possible in all substitutions of the aorta.

[Changes on hemodynamics and oxygen delivery in patients with septic shock]

Since there are still some confusions in hemodynamics and changes of oxygen delivery (DO2) in septic shock which has a high mortality, the 40 septic shock patients were observed in hemodynamics and DO2 in general ICU of Peking Union Medical College Hospital. Both surviving group and nonsurviving group had their hyperdynaminc state in hemodynamics at the beginning of septic shock. In survivors, hemodynamics were back to normal range at the 4th day of septic shock. But nonsurvivors were still in the hyperdynamic state all way to the end stage. A critical level of DO2, which was found only in survivors, was 670 ml/min.m2. The oxygen supply dependency of oxygen consumption (VO2) was found in nonsurvivors even DO2 was highly increased. The oxygen extraction (O2 ext) in nonsurvivors was lower than in survivors when DO2 was lower than critical level. We think that maintaining hyperdynamic state in septic shock does not certainly improve survival rate. In the septic shock patients with pathologic oxygen supply dependency, DO2 is not able to be increased to meet tissue oxygen demand. The changes of O2 ext have a significance in prediction of outcome of septic shock. The current therapies for septic shock have remarkable limitation. So the new treatment methods of septic shock, not only to increases DO2, should be found out for improving the survival rate further.

Ionic bases for electrophysiological distinctions among epicardial, midmyocardial, and endocardial myocytes from the free wall of the canine left ventricle

Recent studies from our laboratory involving syncytial preparations have delineated electrophysiological distinctions between epicardium, endocardium, and a unique population of cells in the deep subepicardial to midmyocardial layers (M region) of the canine ventricle. In the present study, we used standard microelectrode, single microelectrode switch voltage-clamp, and whole-cell patch-clamp techniques to examine transmembrane action potentials, steady-state current-voltage relations, and the 4-aminopyridine-sensitive transient outward current (Ito1) in myocytes enzymatically dissociated from discrete layers of the free wall of the canine left ventricle. Action potential characteristics of myocytes isolated from the epicardium, M region, and endocardium were very similar to those previously observed in syncytial preparations isolated from the respective regions of the ventricular wall. A prominent spike and dome was apparent in myocytes from epicardium and the M region but not in myocytes from endocardium. Action potential duration-rate relations were considerably more pronounced in cells isolated from the M region. Current-voltage relations recorded from cells of epicardial, M region, and endocardial origin all displayed an N-shaped configuration with a prominent negative slope-conductance region. The magnitude of the inward rectifier K+ current (IK1) was 392 +/- 86, 289 +/- 65, and 348 +/- 115 pA in epicardial, M region, and endocardial myocytes, respectively, when defined as steady-state current blocked by 10 mM Cs+. Similar levels were obtained when IK1 was defined as the steady-state difference current measured in the presence (6 mM) and absence of extracellular K+. Ito1 was significantly greater in epicardial and M region myocytes than in endocardial myocytes. At a test potential of +70 mV (holding potential, -80 mV), Ito1 amplitude was 4,203 +/- 2,370, 3,638 +/- 1,135, and 714 +/- 286 pA in epicardial, M region, and endocardial cells, respectively. No significant differences were observed in the voltage dependence of inactivation of Ito1 in the three cell types. The time course of reactivation of Ito1 was slower in cells from the M region compared with either epicardial or endocardial cells. Our data suggest that prominent heterogeneity exists in the electrophysiology of cells spanning the canine ventricular wall and that differences in the intensity of the transient outward current contribute importantly, but not exclusively, to this heterogeneity. These findings should advance our understanding of basic heart function and the ionic bases for the electrocardiographic J wave, T wave, U wave, and long QT intervals as well as improve our understanding of some of the complex factors contributing to the development of cardiac arrhythmias.

Clustering of muscle acetylcholine receptors requires motoneurons in live embryos, but not in cell culture

Previous culture studies have demonstrated that muscle cells autonomously express and cluster ACh receptors (AChRs) and that contact by neurites induces a reorganization of these clusters. We studied these phenomena in zebrafish embryos where the same cells could be examined in vivo and in vitro, and where contacts between cells could be viewed repeatedly. Receptor clusters first appeared when the pioneer growth cones emerged from the spinal cord, were always associated with labeled branches, and developed normally in the presence of neuromuscular transmission blockers. When motoneurons were removed, the muscles failed to cluster receptors. In contrast, muscle cells grown in cell culture uncontacted by nerves clustered AChRs. Our results suggest that clustering of AChRs in living embryos is induced by the presence of neurites and does not occur in the absence of neuronal contact. We suggest that conditions in cell culture, which differ from those in the intact embryo, induce clusters on isolated muscle cells. Moreover, our results demonstrate that receptors cluster without binding transmitter and in the absence of neuronal activity.

Beta-adrenergic modulation of fast inward sodium current in canine myocardium. Syncytial preparations versus isolated myocytes

Reports have suggested that the fast inward sodium current (INa) in cardiac tissues may be modulated by beta-adrenergic stimulation and that such modulation may affect conduction in the setting of myocardial ischemia and infarction. However, many of these studies have used dissociated myocytes or broken cell preparations, whose responses need not necessarily reflect those of syncytial preparations. To investigate further the possibility that beta-adrenergic stimulation of INa may differ in various preparations, we compared the effects of the beta-agonist isoproterenol (ISO) on syncytial canine Purkinje fibers and ventricular muscle preparations, as well as isolated ventricular myocytes. Alterations of the maximum rate of rise of the action potential upstroke (Vmax) were used as an index of changes of INa. ISO (1 microM) had no effect on Vmax of upstrokes of normally polarized (fast responses) or partially depolarized (elevated [K+]o, depressed fast responses) syncytial ventricular muscle preparations or Purkinje fibers. In contrast, lower concentrations of ISO (0.5-1.0 microM) modulated Vmax of isolated ventricular myocytes, depending on the technique used to monitor transmembrane potential. When 2.7 M KCl-filled microelectrodes were used, ISO reduced Vmax of partially depolarized myocytes without affecting Vmax of normally polarized myocytes. However, when myocytes were dialyzed using patch pipettes, ISO reduced Vmax of partially depolarized myocytes and increased Vmax of normally polarized myocytes, effecting a hyperpolarized shift of the normalized inactivation curve relating Vmax to resting membrane potential. The different beta-adrenergic responses of syncytial preparations and nondialyzed and dialyzed myocytes suggest that differences in the ionic or metabolic condition of the preparations likely alter cAMP-dependent responses and channel phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on pathological morphology, clinical features and nuclear DNA contents by flow cytometry in adrenal neoplasms

Pathological morphology, clinical features and nuclear DNA contents determined by flow cytometry (FCM) were studied in 11 cases of normal adrenals and 41 cases of adrenal neoplasms. It was found that despite differences in clinical manifestations and in degrees of cellular atypia of the adenomas their DNA contents were the same as in normal adrenals. On the other hand, the pheochromocytomas were benign in nature, but most of them (16/19) showed DNA aneuploidy and the DNA indices were correlated with their clinical and morphological features.

The formation of terminal fields in the absence of competitive interactions among primary motoneurons in the zebrafish

To make specific synaptic connections, projection neurons extend neurites to regions containing appropriate targets, then form synapses with the correct type and number of target cells. To investigate the mechanisms controlling this process, we have studied the formation of motoneuronal terminal fields in live zebrafish embryos. The primary motoneurons of the zebrafish are identifiable as individuals and innervate neighboring but mutually exclusive territories. To study the first week of their development, which includes embryonic and early larval stages, we labeled identified motoneurons with fluorescent dyes and made sequential observations of the axonal branches of individual neurons. We assessed the roles of competitive interactions and synapse elimination in the formation of specific synapses by identified neurons that innervate neighboring territories. Our results demonstrate that primary motoneurons establish their cell-specific terminal fields primarily by directed outgrowth of branches and formation of neuromuscular junctions almost exclusively on appropriate muscle fibers, rather than by overproduction and selective elimination of inappropriate branches. Retraction of the few branches that are inappropriately placed, though correlated in time with the ingrowth of branches from appropriate motoneurons, occurs independently of the influences of these other cells and when neuromuscular transmission is blocked. We suggest that, similar to the way in which they pioneer peripheral nerve pathways, primary motoneurons establish their cell-specific terminal fields using mechanisms that operate independently of activity and competition. The target or substrate interactions that are likely to instruct directed growth-cone navigation may be similar to the interactions that determine the locations of territorial borders and that instruct the retraction of misplaced branches.

Pathfinding and synapse formation in a zebrafish mutant lacking functional acetylcholine receptors

We induced and characterized a recessive lethal mutation, nic-1, in zebrafish that blocks the function of muscle acetylcholine (ACh) receptors. Homozygous nic-1 embryos are nonmotile and fail to respond to exogenous application of cholinergic agonists, although their muscles contract in response to direct electrical stimulation. Moreover, we do not detect cell surface labeling by alpha-bungarotoxin or monoclonal antibodies that recognize the other three subunits of ACh receptors. Motoneurons, however, establish morphologically normal patterns of innervation and normal neuromuscular junctions. We suggest that neither transmitter-mediated nerve signaling nor any other aspect of ACh receptor function is required for the formation of appropriate nerve connections in this system.

A family with Fabry's disease. Ocular manifestations and transmission electron microscopic examination of a skin lesion biopsy

A family with Fabry's disease including 2 hemizygotes and 3 heterozygotes is reported. The ocular manifestations include tortuosity of conjunctival vessels, Fabry's deposits underlying the anterior capsule of the lens and the whorl-like corneal dystrophy. Foam cells or mulberry cells in the urinary sediment and varying numbers of high electron-dense inclusions in the cytoplasm of endothelial cells in skin lesions are also important in diagnosing this disease. The concentrations of lipid peroxide in the sera of 2 hemizygotes in this report were higher than normal, possibly due to the patients weak ability of anti-oxygenation and malfunction of cells whose plasma membranes are easily attacked by free oxygen radicals. The biochemical and pathological changes, diagnosis, treatment, genetics and prevention of the disease are discussed.

Function of identified motoneurones and co-ordination of primary and secondary motor systems during zebra fish swimming

1. The activity of the two classes of motoneurones, primary and secondary, which innervate myotomal muscle fibres in the zebra fish, was monitored with electromyographic and intracellular techniques. 2. Simultaneous EMG and intracellular recordings from muscle fibres showed that the activity of the two motor systems and of individual primary motoneurones can be distinguished by recording EMG spikes during swimming. 3. Measurements of EMG spikes demonstrated that primary and secondary motoneurones are co-ordinately activated over a wide range of conditions during normal swimming. 4. During swimming the primary motoneurones within a given segment are usually co-activated although they sometimes fire independently. 5. When different primary motoneurones within a given segment are co-activated, they fire nearly synchronously. 6. We conclude that the primary motoneurones are used principally, although not exclusively, during fast swimming, struggling and the startle response, whereas secondary motoneurones function primarily during slower swimming.

Separation of reduced disaccharides derived from glycosaminoglycans by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for the analysis of reduced unsaturated disaccharides derived from enzymatic digestion followed by reduction with sodium borohydride of chondroitin sulfates, dermatan sulfate, heparan sulfate and heparin is described. This method is well suited for the HPLC analysis of glycosaminoglycans (GAGs) because the possibility of obtaining anomeric forms of unsaturated disaccharides is eliminated with provides a major advantage for quantitation. This procedure is more sensitive than existing HPLC methods for the determination of enzymatic degradation products from GAGs. In particular, the resolution of disaccharide products from heparan sulfate is improved after reduction. The applicability of this method for the determination of GAGs in biological samples is demonstrated.