Coevolution with hosts underpins speciation in brood-parasitic cuckoos.

Coevolution between interacting species is thought to increase biodiversity, but evidence linking microevolutionary processes to macroevolutionary patterns is scarce. We leveraged two decades of behavioral research coupled with historical DNA analysis to reveal that coevolution with hosts underpins speciation in brood-parasitic bronze-cuckoos. At a macroevolutionary scale, we show that highly virulent brood-parasitic taxa have higher speciation rates and are more likely to speciate in sympatry than less-virulent and nonparasitic relatives. We reveal the microevolutionary process underlying speciation: Hosts reject cuckoo nestlings, which selects for mimetic cuckoo nestling morphology. Where cuckoos exploit multiple hosts, selection for mimicry drives genetic and phenotypic divergence corresponding to host preference, even in sympatry. Our work elucidates perhaps the most common, but poorly characterized, evolutionary process driving biological diversification.

Chalkbrood disease in honey bees.

Chalkbrood is a fungal disease of honey bee brood caused by Ascosphaera apis. This disease is now found throughout the world, and there are indications that chalkbrood incidence may be on the rise. In this review we consolidate both historic knowledge and recent scientific findings. We document the worldwide spread of the fungus, which is aided by increased global travel and the migratory nature of many beekeeping operations. We discuss the current taxonomic classification in light of the recent complete reworking of fungal systematics brought on by application of molecular methods. In addition, we discuss epidemiology and pathogenesis of the disease, as well as pathogen biology, morphology and reproduction. New attempts at disease control methods and management tactics are reviewed. We report on research tools developed for identification and monitoring, and also include recent findings on genomic and molecular studies not covered by previous reviews, including sequencing of the A. apis genome and identification of the mating type locus.

BDNF mRNA expression is increased in adult rat forebrain after limbic seizures: temporal patterns of induction distinct from NGF.

We have localized brain-derived neurotrophic factor (BDNF) mRNA in rat brain and examined its regulation by seizure activity. In situ hybridization of BDNF 35S-cRNA most prominently labeled neurons in hippocampal stratum pyramidale and stratum granulosum, superficial olfactory cortex, pyramidal cell layers of neocortex, amygdala, claustrum, endopiriform nucleus, anterior olfactory nucleus, and ventromedial hypothalamus. Hybridization to BDNF mRNA was markedly increased in all of these regions after lesion-induced recurrent limbic seizures and within dentate gyrus granule cells following one electrically stimulated epileptiform afterdischarge. In contrast to seizure-elicited changes in nerve growth factor (NGF) mRNA expression, increases in BDNF mRNA occur in a greater number of different neuronal populations and develop several hours more rapidly in extrahippocampal loci. These results indicate that regulation by physiological activity may be an intrinsic property of this class of neurotrophic factor but that, in the recurrent seizure paradigm, different mechanisms mediate increased expression of mRNAs for BDNF and NGF outside hippocampus.

High mobility group (HMG-box) genes in the honeybee fungal pathogen Ascosphaera apis.

The genome of the honeybee fungal pathogen Ascosphaera apis (Maassen) encodes three putative high mobility group (HMG-box) transcription factors. The predicted proteins (MAT1-2, STE11 and HTF), each of which contain a single strongly conserved HMG-box, exhibit high similarity to mating type proteins and STE11-like transcription factors previously identified in other ascomycete fungi, some of them important plant and human pathogens. In this study we characterized the A. apis HMG-box containing genes and analyzed the structure of the mating type locus (MAT1-2) and its flanking regions. The MAT1-2 locus contains a single gene encoding a protein with an HMG-box. We also have determined the transcriptional patterns of all three HMG-box containing genes in both mating type idiomorphs and discuss a potential role of these transcription factors in A. apis development and reproduction. A multiplex PCR method with primers amplifying mat1-2-1 and Ste11 gene fragments is described. This new method allows for identification of a single mating type idiomorph and might become an essential tool for applied and basic research of chalkbrood disease in honeybees.

Control of spoT-dependent ppGpp synthesis and degradation in Escherichia coli.

Escherichia coli has two ppGpp synthetases, PSI and PSII, encoded by the relA and spoT genes. The spoT gene also encodes a ppGpp hydrolase. During exponential growth and under various starvation conditions, the level of ppGpp depends on the balance of ppGpp synthetic and degradative activities of spoT gene products. To find out how these two activities respond to different physiological conditions and to learn about the signals involved in these responses, rates of ppGpp synthesis and degradation were determined in an E. coli B/r delta relA strain during: (1) multiple amino acid deprivation after a nutritional shift-down from glucose amino acids to glucose minimal medium; (2) carbon source starvation after a "glucose runout"; (3) energy starvation by treatment with sodium azide. To each of these conditions, bacteria responded with a similar gradual accumulation of ppGpp, occurring over a period of 20 to 40 minutes, from the basal level of 4 and 24 pmol/OD460 in glucose amino acids and glucose minimal medium, respectively, to about 100 pmol ppGpp/OD460 unit of culture mass. After multiple amino acid deprivation and during azide treatment, the rate of ppGpp synthesis increased and the rate of ppGpp degradation decreased, but in different proportions by the two kinds of treatment. After glucose runout, both ppGpp synthesis and degradation immediately decreased, but the rate of degradation was reduced more, which caused the accumulation of ppGpp despite its reduced synthesis. ppGpp synthesis required continuous protein synthesis, but ppGpp hydrolysis and its control did not: the rate of ppGpp degradation could be instantly up or down-regulated in response to changes in exogenous amino acid or glucose levels in the absence of protein synthesis. The results suggest that PSII is unstable with an average functional lifetime of 40 seconds or less, and that its activity is generated during or shortly after spoT mRNA translation in response to the availability of amino acids. This regulation is responsible for the growth medium-dependent changes in basal levels of ppGpp. ppGpp hydrolysis is controlled, i.e. inhibited, mainly during conditions of physiological stress, such as multiple amino acid deprivation or energy deprivation. This inhibition can be correlated with an inferred accumulation of uncharged tRNA. Since previous reports have indicated that uncharged tRNA inhibits purified SpoT hydrolase in vitro, it is proposed that ppGpp hydrolase activity is, indeed, controlled by the concentration of uncharged tRNA in the cell. Finally, it was found that neither relC, transcriptional regulation of spoT, nor different translation starts of spoT mRNA are directly involved in the environmental control of SpoT hydrolase and PSII activities.

Cell-specific expression of type II calcium/calmodulin-dependent protein kinase isoforms and glutamate receptors in normal and visually deprived lateral geniculate nucleus of monkeys.

In situ hybridization histochemistry and immunocytochemistry were used to map distributions of cells expressing mRNAs encoding alpha, beta, gamma, and delta isoforms of type II calcium/calmodulin-dependent protein kinase (CaMKII), alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionate (AMPA)/ kainate receptor subunits, (GluR1-7), and N-methyl-D-aspartate (NMDA) receptor subunits, NR1 and NR2A-D, or stained by subunit-specific immunocytochemistry in the dorsal lateral geniculate nuclei of macaque monkeys. Relationships of specific isoforms with particular glutamate receptor types may be important elements in neural plasticity. CaMKII-alpha is expressed only by neurons in the S laminae and interlaminar plexuses of the dorsal lateral geniculate nucleus, but may form part of a more widely distributed matrix of similar cells extending from the geniculate into adjacent nuclei. CaMKII-beta, -gamma, and -delta isoforms are expressed by all neurons in principal and S laminae and interlaminar plexuses. In principal laminae, they are down-regulated by monocular deprivation lasting 8-21 days. All glutamate receptor subunits are expressed by neurons in principal and S laminae and interlaminar plexuses. The AMPA/kainate subunits, GluR1, 2, 5, and 7, are expressed at low levels, although GluR1 immunostaining appears selectively to stain interneurons. GluR3 is expressed at weak, GluR 6 at moderate and GluR 4 at high levels. NMDA subunits, NR1 and NR2A, B, and D, are expressed at moderate to low levels. GluR4, GluR6 and NMDA subunits are down-regulated by visual deprivation. CaMKII-alpha expression is unique in comparison with other CaMKII isoforms which may, therefore, have more generalized roles in cell function. The results demonstrate that all of the isoforms are associated with NMDA receptors and with AMPA receptors enriched with GluR4 subunits, which implies high calcium permeability and rapid gating.

Altered mRNA expression for brain-derived neurotrophic factor and type II calcium/calmodulin-dependent protein kinase in the hippocampus of patients with intractable temporal lobe epilepsy.

The expression of brain-derived neurotrophic factor and the alpha subunit of calcium/calmodulin-dependent protein kinase II mRNA in hippocampi obtained during surgical resections for intractable temporal lobe epilepsy were examined. Both calcium/calmodulin-dependent protein kinase II and brain-derived neurotrophic factor are localized heavily within the hippocampus and have been implicated in regulating hippocampal activity (Kang and Schuman [1995] Science 267:1658-1662; Suzuki [1994] Intl J Biochem 26:735-744). Also, the autocrine and paracrine actions of brain-derived neurotrophic factor within the central nervous system make it a likely candidate for mediating morphologic changes typically seen in the epileptic hippocampus. Quantitative assessments of mRNA levels in epileptic hippocampi relative to autopsy controls were made by using normalized densitometric analysis of in situ hybridization. In addition, correlations between clinical data and mRNA levels were studied. Relative to autopsy control tissue, decreased hybridization to mRNA of the alpha subunit of calcium/calmodulin-dependent protein kinase II and increased hybridization to brain-derived neurotrophic factor mRNA were found throughout the granule cells of the epileptic hippocampus. There also was a significant negative correlation between the duration of epilepsy and the expression of mRNA for brain-derived neurotrophic factor. These results are similar qualitatively to those found in animal models of epilepsy and suggest that chronic seizure activity in humans leads to persistent alterations in gene expression. Furthermore, these alterations in gene expression may play a role in the etiology of the epileptic condition.

A metabotropic glutamate receptor agonist regulates neurotrophin messenger RNA in rat forebrain.

We have examined the role of metabotropic glutamate receptor activation in regulating neurotrophin messenger RNA levels in the brain with the use of the selective agonist (1S,3R)-1-aminocy-clopentane-1,3-dicarboxylic acid. Intracerebroventricular injection of (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid into adult adult rats resulted in increased expression of nerve growth factor and brain-derived neurotrophic factor messenger RNA in the hippocampal and pyriform cortex and decreased levels of neurotrophin-3 messenger RNA in the hippocampal dentate gyrus granule cell layer. C-fos messenger RNA levels were also increased throughout hippocampal and cortical subfields following (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid administration. (1S,3R)-1-Aminocyclopentane-1,3-dicarboxylic acid-induced changes in messenger RNA levels occurred without behavioral seizures, yet these changes were similar in magnitude and time course to early changes in neurotrophin and c-fos messenger RNA levels observed following recurrent limbic seizures. In contrast quisqualate, a potent agonist of metabotropic as well as ionotropic kainate/alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors, was only capable of inducing increased expression of brain-derived neurotrophic factor messenger RNA at doses which produced recurrent motor seizures, and both effects were completely inhibited by the non-N-methyl-D-aspartate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Neurotrophin messenger RNA changes induced by (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid were also partially susceptible to 6-cyano-7-nitroquinoxaline-2,3-dione antagonism, as well as the specific N-methyl-D-aspartate receptor antagonist (+)-5-methyl-10,11-dihydroxy-5H-dibenzo(a,d)-cyclohepten-5,10- iminedizoleipine. These results suggest that (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid-sensitive metabotropic glutamate receptors can dramatically increase the expression of neurotrophin and c-fos messenger RNAs in rat forebrain without producing significant behavioral trauma and that these influences may involve ionotropic glutamate receptors in certain brain regions.

N-methyl-D-aspartate receptor dependent transcriptional regulation of two calcium/calmodulin-dependent protein kinase type II isoforms in rodent cerebral cortex.

Alpha Calcium/calmodulin-dependent protein kinase type II (CaMKII-alpha) expression is regulated in an activity-dependent manner, but it is not known whether other CaMKII isoforms (beta, delta, and gamma) are similarly regulated. We examined the activity-dependent regulation of these CaMKII isoforms in vivo, using a model of generalized seizures caused by i.p. injection of kainic acid. Following seizure induction, CaMKII-alpha expression was downregulated and CaMKII-delta expression upregulated while CaMKII-beta and CaMKII-gamma expression was unaffected. A transient downregulation in CaMKII-alpha and a transient increase in CaMKII-delta occurred throughout neocortex in the same temporal order. Although CaMKII-alpha mRNA was decreased by seizure activity, the less abundant, alternatively spliced, CaMKII-alpha33 mRNA was unaffected. Organotypic cortical slice cultures treated with bicuculline and 4-aminopyridine to induce seizure activity also showed a downregulation of CaMKII-alpha mRNA and an upregulation of CaMKII-delta mRNA. Prior exposure to tetrodotoxin prevented the changes in CaMKII-alpha and CaMKII-delta mRNA regulation and this was mimicked by D-L-2-amino-5-phosphonovaleric acid, but not by 6-cyano-2,3-dihydroxy-7-nitro-quinoxaline, suggesting that CaMKII-alpha and CaMKII-delta mRNA expression is regulated in an N-methyl-D-aspartate receptor-dependent manner. Regulation was also transcription dependent. Blocking transcription with actinomycin-D prevented activity-dependent changes in CaMKII-alpha and CaMKII-delta mRNA, but produced opposite effects on basal transcription, resulting in more stabilized CaMKII-alpha mRNA and less stabilized CaMKII-delta mRNA. These results reveal unique patterns of seizure-induced alterations in CaMKII mRNAs. Activity-dependent changes in subunit composition could, therefore, differentially influence the functional attributes of the CaMKII holoenzyme.

Differential regulation of brain-derived neurotrophic factor and type II calcium/calmodulin-dependent protein kinase messenger RNA expression in Alzheimer's disease.

The relative levels of messenger RNA for brain-derived neurotrophic factor and the alpha subunit of calcium/calmodulin-dependent protein kinase type II were examined in hippocampal sections from Alzheimer's diseased and age matched non-diseased brains by in situ hybridization histochemistry. Consistent with previous reports in monkey and rodent, calcium/calmodulin-dependent protein kinase II messenger RNA was prevalent throughout the dentate gyrus, all the principal hippocampal subfields, and adjacent cortical regions. A distribution consistent with the dendritic localization of calcium/calmodulin-dependent protein kinase II was also observed. In contrast, brain-derived neurotrophic factor messenger RNA levels were much lower than calcium/calmodulin-dependent protein kinase II messenger RNA levels and were less widely distributed. Within the hippocampus of Alzheimer's diseased brains, levels of calcium/calmodulin-dependent protein kinase II messenger RNA were increased and levels of brain-derived neurotrophic factor messenger RNA were decreased in comparison with matched controls. These changes were consistently seen in four out of six cases processed for both messenger RNA species and ranged from 150-300% relative to non-diseased brain tissue for calcium/calmodulin-dependent protein kinase II and 20-70% for brain-derived neurotrophic factor. These results suggest that within the Alzheimer's hippocampus an altered program of gene expression is occurring leading to aberrant levels of both calcium/calmodulin-dependent protein kinase II and brain-derived neurotrophic factor messenger RNA. Previous studies of the activity-dependent regulation of these messenger RNA species suggest these results are consistent with a decrease in afferent activity within the Alzheimer's hippocampus.

The messenger RNA encoding VGF, a neuronal peptide precursor, is rapidly regulated in the rat central nervous system by neuronal activity, seizure and lesion.

The VGF gene encodes a neuronal secretory-peptide precursor that is rapidly induced by neurotrophic growth factors and by depolarization in vitro. VGF expression in the animal peaks during critical periods in the developing peripheral and central nervous systems. To gain insight into the possible functions and regulation of VGF in vivo, we have used in situ hybridization to examine the regulation of VGF messenger RNA by experimental manipulations, and have found it to be regulated in the CNS by paradigms that affect electrical activity and by lesion. Inhibition of retinal electrical activity during the critical period of visual development rapidly repressed VGF messenger RNA in the dorsal lateral geniculate nucleus of the thalamus. In the adult, kainate-induced seizures transiently induced VGF messenger RNA in neurons of the dentate gyrus, hippocampus, and cerebral cortex within hours. Cortical lesion strongly induced VGF messenger RNA in ipsilateral cortex within hours, and strongly repressed expression in ipsilateral striatum. Ten days postlesion there was a delayed induction of VGF messenger RNA in a portion of deafferented striatum where compensatory cortical sprouting has been detected. Expression of the neuronal secretory-peptide precursor VGF is therefore modulated in vivo by monocular deprivation, seizure, and cortical lesion, paradigms which lead to neurotrophin induction, synaptic remodeling and axonal sprouting.

Preserved atrial natriuretic peptide secretory function after cardiac transplantation.

The purpose of this investigation was to determine whether atrial natriuretic peptide (ANP) secretory function is preserved after cardiac transplantation. Thirteen hemodynamically stable outpatients performed supine exercise on a bicycle an average of 7 months after orthotopic cardiac transplantation. Right atrial pressure increased 2.2-fold (6 +/- 1 to 13 +/- 2 mm Hg) and pulmonary artery wedge pressure 2.1-fold (11 +/- 1 to 23 +/- 7 mm Hg) with exercise in the transplant recipients. Resting venous ANP level (114 +/- 19 pg/ml) and peak exercise venous level (373 +/- 61 pg/ml) was elevated in transplant recipients (p less than 0.001) compared with control subjects (21 +/- 1 and 92 +/- 14 pg/ml, respectively. This represents a 3.3-fold (114 +/- 19 to 373 +/- 61 pg/ml) increase in the ANP level from resting to exercise in transplant recipients and a 4.4-fold (21 +/- 1 to 92 +/- 14 pg/ml) increase in control subjects. A correlation between venous ANP levels and hemodynamics (right atrial pressure) was observed r = 0.49 p = 0.01. It is concluded that ANP levels at rest are elevated after cardiac transplant, the levels correlate with the intracardiac hemodynamics, and exercise-induced augmentation of plasma levels occurs.

A limited axillary thoracotomy as primary treatment for recurrent spontaneous pneumothorax.

Recurrent spontaneous pneumothorax often requires surgical treatment following variable periods of chest tube therapy. A limited axillary thoracotomy provides sufficient exposure to isolate or excise pulmonary blebs and perform a pleurodesis. Prompt use of this surgical approach in lieu of the initial placement of a thoracostomy tube avoids prolonged hospitalization and a significant failure rate of thoracostomy tubes to resolve this problem. This operation can also prevent recurrence, a significant problem for this pathologic process. Fourteen patients with recurrent spontaneous pneumothorax underwent an axillary thoracotomy as either primary treatment or within 72 h of thoracostomy tube placement. The average follow-up was 38 months for the initial 10 patients and 23 months for the entire group. The procedure averaged 66 min in duration. The average incision was 3.3 cm in length. There was an equal male/female ratio and right-left distribution. The patients were discharged an average of 4.2 days after surgery. There were no complications. The most recent six patients with a recurrent pneumothorax were surgically treated on the day of admission without a preoperative chest tube. The other eight patients had a thoracostomy tube for control of the pneumothorax, with surgery performed within 72 h of tube placement. A limited axillary thoracotomy corrected the underlying pathology, hastened hospital discharge, limited pain, prevented short-term recurrence, and was cosmetically acceptable. A limited axillary thoracotomy is the operation of choice when a spontaneous pneumothorax requires surgery. This surgical approach has become our primary treatment for recurrent pneumothorax, avoiding the use of a preoperative thoracostomy tube and unnecessary delay, with excellent results for the patient.

Decreased expression of the alpha subunit of Ca2+/ calmodulin-dependent protein kinase type II mRNA in the adult rat CNS following recurrent limbic seizures.

Calcium/calmodulin-dependent protein kinase type II (CamKII) is a ubiquitous brain enzyme implicated in a wide variety of neuronal processes. Understanding CamKII has become increasingly complicated with the recent identification of multiple gene transcripts coding for separate subunits. Previous studies have shown that mRNA for the alpha subunit of CamKII can be increased by reduction of afferent input. In this study we have examined the regulation of alpha CamKII mRNA following increased activity due to seizures. Using in situ hybridization with a cRNA probe against the rat alpha CamKII sequence we found reduced levels of hybridization following limbic seizures induced by lesions of the hilus of the dentate gyrus. Hybridization was most dramatically reduced in the granule cells of the dentate gyrus and the pyramidal cells of hippocampal region CA1. There were also significant reductions in hybridization in the superficial layers of neocortex and piriform cortex. In each of these region hybridization was decreased in the molecular layers which is consistent with the reported dendritic localization of alpha CamKII mRNA. All changes in mRNA content were transient, with maximal reductions at 24 h following lesion placement and a return to control levels by 96 h. These findings demonstrate the negative regulation of alpha CamKII mRNA by seizure activity and raise the possibility that synthesis of this kinase may be regulated by normal physiological activity.

Intraoperative lymphatic mapping for non-small cell lung cancer: the sentinel node technique.

BACKGROUND: The purpose of the study was to determine the accuracy and role of the sentinel node technique in patients with non-small cell lung cancer. METHODS: This study was carried out on 36 consecutive patients undergoing lung resection. Peritumoral tissue was infiltrated with isosulfan blue dye and the first lymph node to stain was identified as a sentinel node. Sensitivity and specificity of the sentinel node in predicting the status of other lymph node stations were determined. RESULTS: Seventeen patients had sentinel lymph nodes. In 9 of these 17 cases neither the sentinel node nor any other lymph node contained metastatic carcinoma. In 5 cases the sentinel node was in the mediastinum and documented unexpected N2 disease. In 19 patients no sentinel node was found. Final lymph node statuses were N0 in 13 patients, N1 in 5, and N2 in 1. CONCLUSIONS: The use of isosulfan blue for intraoperative lymphatic mapping is feasible. The specificity in our experience was good; 9 of 9 patients with negative sentinel nodes were found to be N0 on the final pathology report. Unexpected N2 disease was found in 5 patients. The accumulation of further experience will determine the role of the sentinel node technique in patients with non-small cell lung cancer.

Seizure-induced alterations of plasma membrane calcium ATPase isoforms 1, 2 and 3 mRNA and protein in rat hippocampus.

Improper intracellular regulation of the ubiquitous second messenger, calcium, has been linked to several pathological conditions. The plasma membrane calcium ATPase (PMCA) is one of the primary systems for translocating calcium from the cytosol to the extracellular milieu. As an initial assessment of the possible involvement of PMCAs in kainate (KA)-induced neurodegeneration, we have determined the effect of KA-induced seizures upon PMCA mRNA and protein. In situ hybridization was performed on tissue from adult male Sprague-Dawley rats sacrificed at various time points following i.p. injection of KA. KA altered the expression within the hippocampal subfields for mRNAs of PMCA isoforms 1 and 2. PMCA 1 and 2 mRNAs exhibited hybridization below control levels 12-48 h post-injection within CA1 and CA3. Within the dentate gyrus, PMCA 2 mRNA hybridized below control levels 4 h post-injection, but recovered to control levels by 24 h post-injection. Alterations in combined PMCA protein levels occurred at all time points examined post-injection. These observations provide evidence that KA-induced seizures alter the PMCAs at the mRNA and protein levels, suggesting a possible role for this calcium efflux system in the neuronal degeneration inherent to this paradigm.

Adenine nucleotide content in cold preserved human donor hearts and subsequent cardiac performance after orthotopic heart transplantation.

Myocardial high-energy phosphate content has been used as a parameter to evaluate the adequacy of donor organ preservation. The purpose of this study was to assess current techniques of preservation by measuring high-energy phosphates in cold preserved (4 degrees C) human donor hearts. Endomyocardial biopsy samples of the donor heart right ventricular septum (n = 24) were compared with samples from patients with normal cardiac function evaluated before chemotherapy (n = 12). Left ventricular and right ventricular ejection fractions were measured by means of radionuclide angiography early (24 to 72 hours) and late (mean 42 days) postoperatively. Mean total cold ischemic time was 146 +/- 54 minutes (range, 89 to 340 minutes). ATP nmol/mg noncollagenous protein in donor hearts was 38.2 +/- 10.7 and 31.9 +/- 13.6 (p = NS) in normal hearts. Early postoperative left ventricular and right ventricular ejection fraction was 55% +/- 14% and 40% +/- 9%, respectively. Late postoperative left ventricular and right ventricular ejection fraction was 64% +/- 14% and 50% +/- 10%, respectively; both represent significant increases in right and left ventricular ejection fraction (p less than 0.05). No correlation was found between ischemic time and donor ATP, ischemic time and ejection fraction, or ejection fraction and ATP. Three patients with normal donor heart ATP content had severe, but reversible, early graft dysfunction. In summary, currently used human donor heart preservation techniques are associated with normal values of high-energy phosphates and usually excellent early and late postoperative graft function.(ABSTRACT TRUNCATED AT 250 WORDS)

Permanent pacing in heart transplant recipients: underlying causes and long-term results.

Although the majority of heart transplant recipients have a satisfactory heart rate, a substantial number require a permanent pacemaker. In 7 of 46 heart transplant patients at our institution symptomatic bradycardia developed, necessitating implantation of a transvenous pacemaker. The average time from heart transplantation to pacer insertion was 25 days. The average donor age, ischemic period, and crossclamp time was 28 years, 182 minutes, and 113 minutes, respectively. A long aortic crossclamp time (greater than 83 minutes) increased the risk for conduction abnormalities in the sinoatrial node. No patient had rejection before the pacer implantation. Five of the seven patients continue to be paced a significant amount of a 24-hour period. Only one patient has had considerable improvement in 3 years, requiring pacing only 3% of a monitored 24-hour period. This patient had the longest ischemic time and the most rejection episodes after implantation of the pacemaker. One patient was paced 100% until a second heart transplantation was done, without a subsequent need for pacing. The other five patients' hearts continue to be paced between 80% and 100% of a 24-hour monitored period. The donor intrinsic heart rates of these five patients produce symptomatic bradycardia. The success of AAI pacing in all patients indicates normal conduction below the sinoatrial node. The injury or dysfunction resulting in bradycardia was isolated to the sinoatrial node. Long-term follow-up in three patients (greater than 3 years) shows the need for pacing to be intermittent but long term. Most patients never fully recover from symptomatic bradycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Remnant atrial function in human and animal recipients of a total artificial heart.

The native atria remains intact after total artificial heart (TAH) implantation. The electrical activity of the recipient's atria can be recorded from wires placed during TAH implantation. Regulating TAH heart rate by coupling it with native atrial activity has the potential for a more physiologically responsive TAH. The reactivity of the atrial impulse rate is a critical component of this link, but little is known about atrial responsiveness after TAH placement. Two human and three animal TAH recipients had recordable atrial electrical activity. Human atrial impulse rate after TAH was relatively constant at rest but unresponsive to physiologic stimuli. Analysis of human atrial contraction provided no discernable effect on ventricular filling. Animal atrial impulse rate at rest was more rapid than calves without a TAH. The bovine TAH recipients had an atrial impulse rate that responded to catecholamine stimulation and blockade. Isoproterenol caused a significant rise in atrial impulse rate (152 +/- 16 impulses per minute to 216 +/- 24 impulses per minute; p < 0.05) and propranolol caused a decrease in atrial impulse rate (142 +/- 20 impulses per minute to 122 +/- 19 impulses per minute; p > 0.05). Despite beta blockade, the atrial impulse rate remained abnormally elevated secondary to unknown factors. Animal atrial contraction did appear to intermittently augment TAH ventricular filling. These data indicate that the atria remains electrically intact after TAH implantation. The human atrial impulse rate was unresponsive to physiologic stimuli although the animal atrial impulse rate was affected by exogenous catecholamine administration, but the rate remained abnormally rapid.(ABSTRACT TRUNCATED AT 250 WORDS)

Optimization of liposome mediated transfection of a neuronal cell line.

A cell line derived from sensory neurons was transfected with high efficiency using cationic liposomes, formulated from 3 beta [N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol) and dioleoyl L-alpha-phosphatidylethanolamine (DOPE). This is the first time that cationic liposomes of this type have been reported to transfect a neuronal cell line. We used a reporter gene construct expressing beta-galactosidase under the control of the cytomegalovirus immediate early promoter and routinely observed transfection efficiencies > 40%. Parameters affecting transfection efficiency were examined and the ratio of DNA to liposome proved to be crucial. Liposome formulation procedures and cell transfection protocols devised here will be used as a basis for further in vivo and in vitro work.