Intersections between blood cell development and leukemia genes

Hematopoietic development is regulated in large part by transcription factors that control cell fate decisions and cellular differentiation. Several genes first discovered in the context of chromosomal translocations in leukemia also serve important functions in blood cell development. Gene-targeting experiments related to two of these factors, SCL/tal-1 and translocation-ets-leukemia (TEL), are reviewed here. SCL/tal-1, a T-cell basic helix-loop-helix oncoprotein, is required for the formation of all hematopoietic lineages. In addition, it is essential for angiogenesis in the yolk sac, indicating a dual function in blood and vessel development. TEL, an ets-related factor which is translocated to a variety of other genes in leukemias, is also required for proper angiogenesis in the yolk sac. Additional studies, however, demonstrate that TEL function is necessary for hematopoiesis to be established in the bone marrow microenvironment. These studies emphasize the intrinsic roles of leukemia-associated transcription factors in normal blood cell and vessel development.

Determination of heparin-induced IgG antibody in heparin-induced thrombocytopenia type II

BACKGROUND

Heparin-induced thrombocytopenia is a relatively uncommon but severe side-effect of heparin therapy. Heparin-induced IgG antibody has been elucidated to be the main isotype and the most pathogenic antibody in the pathophysiology. As affected patients are at high risk of developing thrombotic events, confirmation of the clinical diagnosis and avoidance of heparin re-exposure are important and desirable.

MATERIALS AND METHODS

In the present study, heparin-induced IgG was measured by the binding of neoantigens, which were prepared by incubating FITC-heparin with platelet factor 4 present in normal serum. The cross-reactivities of heparin-induced IgG with low-molecular-weight heparin and danaparoid were analysed by competitive binding.

RESULTS

A total of 81 clinically suspected heparin-induced thrombocytopenia type II patients were analysed. Thirty-seven of 38 heparin-induced thrombocytopenia type II patients, in whom thromboembolism was confirmed by objective methods, had elevated relative fluorescence intensity ratios (patient normal control) and 36 had positive heparin-induced platelet activation results. The prevalence of heparin-induced IgG in heparin-induced thrombocytopenia type II patients was 97.4%. Positive heparin-induced IgG results were: 0/319 healthy volunteers, 0/38 other thrombo-cytopenia and 2/56 heparin/low-molecular-weight heparin-receiving patients without thrombocytopenia, 2/41 hyperbilirubinaemic patients and 2/50 hyperlipidaemic patients. A small amount of cross-reaction assays showed similar results as obtained in heparin-induced platelet activation.

CONCLUSION

Our results suggest that a very high frequency of heparin-induced IgG in heparin-induced thrombocytopenia type II patients can be detected using a novel antigen assay. The rapid determination of pathogenic heparin-induced IgG may be a useful tool for the rapid diagnosis of heparin-induced thrombocytopenia type II that could facilitate further management of the patients.

Which form of dopamine is the substrate for the human dopamine transporter: the cationic or the uncharged species?

The question of which is the active form of dopamine for the neuronal dopamine transporter is addressed in HEK-293 cells expressing the human dopamine transporter. The Km value for [3H]dopamine uptake fell sharply when the pH was increased from 6.0 to 7.4 and then changed less between pH 7.4 and 8.2. The KI for dopamine in inhibiting the cocaine analog [3H]2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane binding displayed an identical pH dependence, suggesting that changes in uptake result from changes in dopamine recognition. Dopamine can exist in the anionic, neutral, cationic, or zwitterionic form, and the contribution of each form was calculated. The contribution of the anion is extremely low (</=0.1%), and its pH dependence differs radically from that of dopamine binding. The increase in the neutral form upon raising the pH can model the results only when the pKa1 (equilibrium neutral-charged) is set to a much lower value (6.8) than reported for dopamine in solution (8.86). The sum of cationic and zwitterionic dopamine concentrations remained constant over the entire pH range studied. These forms are the likely transporter substrates with pH-dependent changes occurring in their interaction with the transporter. The binding of dopamine, a hydroxylated phenylethylamine derivative, displays the same pH dependence as guanethidine, a heptamethyleniminoethyl- guanidine derivative fully protonated under our conditions. An ionizable residue in the transporter could be involved that does not interact with or impact the binding of bretylium, a quaternary ammonium phenylmethylamine derivative that is always positively charged and shows only a minor reduction in KI upon increasing pH.

Improvements in the infectivity of cryopreserved third-stage larvae of Angiostrongylus cantonensis using a programmable freezer

Although there have been some advances in the cryopreservation of Angiostrongylus cantonensis, the degrees of viability and infectivity of the cryopreserved developmental stages have not been high. A two-step freezing protocol using a programmable freezer was determined to be effective in improving the infectivity of the cryopreserved third-stage larvae of this parasite. After washing steps and suspension in 10% (v/v) dimethylsulfoxide and equilibrium at room temperature the larvae were placed into the freezer. The temperature was lowered first at 0.8 degrees C/min from room temperature to -40 degrees C and then at 10 degrees C/min to -70 degrees C. The samples were plunged into liquid nitrogen. After storage in liquid nitrogen for 7-15 days the larvae were thawed rapidly in 37 degrees C water and 27.6% were found to show vigorous "S-shape" movement without significant changes in appearance. These larvae (50/rodent) could develop to the fifth stage in mice (42.6%) and establish patent infection in rats (40.4%). Moreover, there was no significant difference in the recovery rates of cryopreserved worms and their unfrozen counterparts. These findings indicate that steady precooling conditions may decrease damage with regard to the infectivity of cryptopreserved third-stage larvae of A. cantonensis.

Singlet oxygen is the major species participating in the induction of DNA strand breakage and 8-hydroxydeoxyguanosine adduct by lead acetate

To investigate DNA damage induced by Pb2+ and its prevention by scavengers, we determined DNA strand breakage and the formation of 8-hydroxydeoxyguanosine (8-OHdG) in DNA using plasmid relaxation assay and HPLC with electrochemical detection, respectively. Lead acetate induced DNA strand breakage in 10 mM of Hepes buffer, pH 6.8, in a time- and dose-dependent manner. Compared with lead, zinc acetate did not significantly induce DNA breakage. The singlet oxygen scavengers NaN3 and 2,2,6,6-tetramethyl-4-piperidone (TEMP) inhibited lead-induced DNA breakage more efficiently than the hydroxyl radical scavengers mannitol and DMPO. Deuterium oxide (D2O), a singlet oxygen enhancer, potentiated lead-induced DNA breakage. At low ratios to Pb2+, NADPH, glutathione, and 2-mercaptoethanol enhanced lead-induced DNA breakage, whereas high ratios of these agents protected it. Catalase and superoxide dismutase (SOD) did not protect DNA breaks induced by Pb2+. Lead-induced DNA breakage was markedly enhanced by H2O2, and this induction was inhibited by NaN3, TEMP, EDTA, catalase, BSA, and glutathione. In contrast, mannitol and SOD potentiated Pb2+/H2O2-induced DNA breaks. The results indicate that singlet oxygen, lead, and H2O2 are all involved in the reaction system, whereas hydroxyl radical and superoxide did not. Lead could cause a small amount of 8-OHdG formation in calf thymus DNA and dose-dependently induced the formation of this adduct in the presence of H2O2. Singlet oxygen scavengers were more effective than hydroxyl radical scavengers in protection from lead/H2O2-induced 8-OHdG adducts. Taken together, these results suggest that lead may induce DNA damage through a Fenton-like reaction and that singlet oxygen is the principal species involved.

Factors influencing the functional outcome of patients with acute epidural hematomas: analysis of 200 patients undergoing surgery

OBJECTIVE

To determine the prognostic factors of the functional outcome of patients surgically treated for acute epidural hematomas.

METHODS

Two hundred patients who consecutively underwent neurosurgery for acute epidural hematomas over the past 9-year period were studied. Clinical characteristics, radiologic findings, and the time intervals with regard to treatment course were investigated to determine the interactions between all these factors and functional outcome.

RESULTS

Functional outcome showed a significant correlation with preoperative consciousness state, Glasgow Coma Scale score, pupillary sizes, and motor posturing (chi2 test, p < 0.05). Functional outcome correlated with the period of brain herniation, the length of time of the operation, as well as the period of hospitalization (chi2 test, p < 0.05), but not with the length of time of craniotomy decompression relative to the length of time from the injury until admission. The radiologic findings of the associated brain injury, the size and the density of the clot, the degree of the brain shift, and the obliteration of the basal cisterns significantly correlated with functional outcome (chi2 test, p < 0.05), whereas no significance was attributable to skull fracture. Multivariate analysis indicated that the following four factors independently correlated with functional outcome: (1) associated brain injury, (2) best motor response, (3) hematoma volume, and (4) period of hospitalization (chi2 test, p < 0.05). A combination of the four factors led to the prediction of the functional outcome with 91% accuracy (1.5 % falsely pessimistic predictions and 7.5 % falsely optimistic prediction) and 82.1% at over 90% confidence level. These four parameters correlated significantly with preoperative neurologic deterioration (chi2 test, p < 0.05).

CONCLUSION

This study identifies the risk factors involved in the functional outcome of patients who underwent surgical treatment for acute epidural hematomas. Our results indicate that associated brain injury plus best motor response are the optimal set of two prognostic indicants, with 87% correct predictions and 70.1% at over a 90% confidence level. Prevention of in-hospital neurologic deterioration would improve the patients' functional outcome with a resultant unfavorable recovery rate ranging from 11.5% to 17%.

Orbital rhinocerebral mucormycosis associated with diabetic ketoacidosis: report of survival of a 10-year-old boy

Cerebral mucormycosis is a rare fungal infection that occurs mostly in association with diabetic ketoacidosis. This central nervous system infection is characterized by a rapid decline in clinical status, and has been recognized as a uniformly fatal event if aggressive therapy is not instituted. We report a diabetic child who presented with blurred vision, chemosis, and pain in the left periorbital region noted for about 1 week during an episode of ketocidosis. Neurologic examinations revealed that there was a decreased range of motion in the upward and lateral gaze, along with incomplete pupillary dilatation and papilledema of the left eye. Imaging studies demonstrated left-side orbital cellulitis, paranasal sinusitis, and a large lobulated abscess in the left frontal lobe. Two surgical procedures, including functional endoscopic sinus surgery for sinus debridement and a subsequent open craniotomy for abscess resection were performed. Pathologic specimens obtained from the abscess wall revealed necrotic inflammation and wide, nonseptate hyphae with right angle branching, which are typical characteristics of the family Mucoraceae. Postoperatively, the patient was treated with 1.5 g of amphotericin B over a 7-week period, and aggressive diabetic control for 2 months. Through the combination of medical and surgical treatment the child made an uneventful recovery.

The TEL/ETV6 gene is required specifically for hematopoiesis in the bone marrow

The TEL (translocation-Ets-leukemia or ETV6) locus, which encodes an Ets family transcription factor, is frequently rearranged in human leukemias of myeloid or lymphoid origins. By gene targeting in mice, we previously showed that TEL-/- mice are embryonic lethal because of a yolk sac angiogenic defect. TEL also appears essential for the survival of selected neural and mesenchymal populations within the embryo proper. Here, we have generated mouse chimeras with TEL-/- ES cells to examine a possible requirement in adult hematopoiesis. Although not required for the intrinsic proliferation and/or differentiation of adult-type hematopoietic lineages in the yolk sac and fetal liver, TEL function is essential for the establishment of hematopoiesis of all lineages in the bone marrow. This defect is manifest within the first week of postnatal life. Our data pinpoint a critical role for TEL in the normal transition of hematopoietic activity from fetal liver to bone marrow. This might reflect an inability of TEL-/- hematopoietic stem cells or progenitors to migrate or home to the bone marrow or, more likely, the failure of these cells to respond appropriately and/or survive within the bone marrow microenvironment. These data establish TEL as the first transcription factor required specifically for hematopoiesis within the bone marrow, as opposed to other sites of hematopoietic activity during development.

Neurturin exerts potent actions on survival and function of midbrain dopaminergic neurons

Glial cell line-derived neurotrophic factor (GDNF) exhibits potent effects on survival and function of midbrain dopaminergic (DA) neurons in a variety of models. Although other growth factors expressed in the vicinity of developing DA neurons have been reported to support survival of DA neurons in vitro, to date none of these factors duplicate the potent and selective actions of GDNF in vivo. We report here that neurturin (NTN), a homolog of GDNF, is expressed in the nigrostriatal system, and that NTN exerts potent effects on survival and function of midbrain DA neurons. Our findings indicate that NTN mRNA is sequentially expressed in the ventral midbrain and striatum during development and that NTN exhibits survival-promoting actions on both developing and mature DA neurons. In vitro, NTN supports survival of embryonic DA neurons, and in vivo, direct injection of NTN into the substantia nigra protects mature DA neurons from cell death induced by 6-OHDA. Furthermore, administration of NTN into the striatum of intact adult animals induces behavioral and biochemical changes associated with functional upregulation of nigral DA neurons. The similarity in potency and efficacy of NTN and GDNF on DA neurons in several paradigms stands in contrast to the differential distribution of the receptor components GDNF Family Receptor alpha1 (GFRalpha1) and GFRalpha2 within the ventral mesencephalon. These results suggest that NTN is an endogenous trophic factor for midbrain DA neurons and point to the possibility that GDNF and NTN may exert redundant trophic influences on nigral DA neurons acting via a receptor complex that includes GFRalpha1.

GFRalpha1 is an essential receptor component for GDNF in the developing nervous system and kidney

Glial cell line-derived neurotrophic factor (GDNF) is a distant member of the TGFbeta protein family that is essential for neuronal survival and renal morphogenesis. We show that mice who are deficient in the glycosyl-phosphatidyl inositol (GPI) -linked protein GFRalpha1 (GDNFRalpha) display deficits in the kidneys, the enteric nervous system, and spinal motor and sensory neurons that are strikingly similar to those of the GDNF- and Ret-deficient mice. GFRalpha1-deficient dopaminergic and nodose sensory ganglia neurons no longer respond to GDNF or to the structurally related protein neurturin (NTN) but can be rescued when exposed to GDNF or neurturin in the presence of soluble GFRalpha1. In contrast, GFRalpha1-deficient submandibular parasympathetic neurons retain normal response to these two factors. Taken together with the available genetic and biochemical data, these findings support the idea that GFRalpha1 and the transmembrane tyrosine kinase Ret are both necessary receptor components for GDNF in the developing kidney and nervous system, and that GDNF and neurturin can mediate some of their activities through a second receptor.

Improvement in the identification of intestinal parasites by a concentrated merthiolate-iodine-formaldehyde technique

To increase the sensitivity of the merthiolate-iodine formaldehyde (MIF) technique in detecting various stages of intestinal parasites in stool specimens, a concentration step was added before preserving the stool specimen with MIF solution. This step involved mixing the stool specimen in 10% formalin, filtering the mixture through a double-layered cotton filter, and removing most of the liquid content. This modification was evaluated in a large screening program. Its positive identification of 10 helminths and 2 protozoa was comparable to formalin-ethyl acetate (FEA) sedimentation and hookworm eggs were readily recognizable. Although the modified MIF technique requires an overnight drying procedure, only a few simple procedures are involved in the concentrating step. This technique is relatively simple and suitable for large-scale screening programs or epidemiologic studies.

Evaluation of quantitative buffy coat analysis in the detection of canine Dirofilaria immitis infection: a model to determine its effectiveness in the diagnosis of human filariasis

Quantitative buffy coat (QBC) analysis has been reported to have a high degree of methodical sensitivity in the detection of human filariasis. This study was conducted to evaluate its usefulness in the diagnosis of filariasis using a Dirofilaria immitis/dog model. By necropsy of 244 stray dogs, 40.6% of the animals were found to harbor 1-58 worms of D. immitis (mean 6.5 +/- 8.4 worms/infected dog). The QBC analysis and thick blood smear (TBS) method detected microfilaremia in 31.6% and 21.3% of these dogs, respectively. The results of these two methods were highly correlated with the presence of bisexual worms in the dogs. The QBC analysis was more sensitive (55% versus 39%) and efficient (79% versus 72%) than the conventional TBS method. However, accurate speciation of the microfilariae was impossible using the QBC analysis. Although this technique is more sensitive, simpler, and less time-consuming and does not require as much skill or experience in comparison with the conventional TBS method, the failure in speciation of the parasites may limit its usefulness.

Acetyl-CoA carboxylase control of fatty acid oxidation in hearts from hibernating Richardson's ground squirrels

Although mammalian hibernators rely on stored body fat as a source of energy, direct measurement of energy substrate preference in heart tissue during hibernation, as well as potential mechanisms controlling fatty acid oxidation has not been examined. In order to determine whether an increase in fatty acid utilization occurs during hibernation, glucose and palmitate oxidation were measured in isolated working hearts from hibernating and non-hibernating Richardson's ground Squirrels. Hearts were perfused at either 37 degrees or 5 degrees C with perfusate containing 11 mM [U-14C]glucose and 1.2 mM [9,10-3H]palmitate, which allowed for direct measurement of both glucose oxidation (14CO2 production) and fatty acid oxidation (3H2O production). The contribution of fatty acid oxidation as a source of citric acid cycle acetyl-CoA was significantly greater in hearts from hibernating animals, compared to hearts from non-hibernating animals. Since acetyl-CoA carboxylase (ACC) regulates cardiac fatty acid oxidation (producing malonyl-CoA, a potent inhibitor of mitochondrial fatty acid uptake), we measured the activity and expression of ACC in these hearts. ACC activity was significantly decreased in hibernating ground squirrels, regardless of whether ACC was assayed at 37 degrees or 5 degrees C. This decrease in activity could not be explained by a change in the activity of 5'AMP-activated protein kinase, which can phosphorylate and inhibit ACC. Rather, the expression of the 280 kDa isoform of ACC (which predominates in cardiac muscle) was decreased in hearts from hibernating squirrel hearts. This suggests that a down regulation of ACC expression occurs as an adaptation for the increased utilization of fatty acid in hearts of hibernating ground squirrels.

Effect of ginseng saponins on exercise performance in non-trained rats

Short-term (4 days), but not acute, treatment with ginseng saponin (GS, 10 and 20 mg/kg/day) significantly prolonged the aerobic endurance of non-trained rats exercising at approximately 70% VO2max. Compared to the saline controls, GS treatment significantly increased the plasma free fatty acid (FFA) level and maintained plasma glucose level during exercise. Both the liver and skeletal muscle glycogen levels of the GS-treated rats were slightly higher than those of saline-treated controls after exhaustive exercise. These results indicate that GS enhances exercise endurance by altering fuel homeostasis during prolonged exercise, presumably by increasing FFA utilization in preference over glucose for cellular energy demands. To further search for the active components responsible for the ergogenic effect of GS, it was found that a GS preparation devoid of Rg1 and Rb1 failed, whereas injection of either Rg1 or Rb1 enhanced aerobic exercise performance. These results indicate that both Rg1 and Rb1 are key ingredients in GS-mediated enhancement in aerobic endurance.

Effect of taurine on toxicity of copper in rats

An attempt was made to study the effect of taurine on the toxicity of copper in male Wistar rats. The rats were divided into eight groups and fed different diets with or without supplement of 5% taurine and 150-600 ppm copper for 2 months. It was found that the levels of copper and malondialdehyde (MDA) in the liver, and the activities of aspartate transaminase (AST) and alanine transaminase (ALT) in the plasma of rats were increased with the increasing dose of copper. However, the levels of copper and MDA, and the enzyme activities of AST and ALT in the rats fed with supplement of taurine were significantly lower than in the rats fed without supplement of taurine. The level of copper in the faeces of rats treated with taurine and copper was higher than that of rats treated with copper alone. It indicated that taurine might play a role in reducing the toxic effect of copper in rats.

Persephin, a novel neurotrophic factor related to GDNF and neurturin

A novel neurotrophic factor named Persephin that is approximately 40% identical to glial cell line-derived neurotrophic factor (GDNF) and neurturin (NTN) has been identified using degenerate PCR. Persephin, like GDNF and NTN, promotes the survival of ventral midbrain dopaminergic neurons in culture and prevents their degeneration after 6-hydroxydopamine treatment in vivo. Persephin also supports the survival of motor neurons in culture and in vivo after sciatic nerve axotomy and, like GDNF, promotes ureteric bud branching. However, in contrast to GDNF and NTN, persephin does not support any of the peripheral neurons that were examined. Fibroblasts transfected with Ret and one of the coreceptors GFRalpha-1 or GFRalpha-2 do not respond to persephin, suggesting that persephin utilizes additional, or different, receptor components than GDNF and NTN.

Parasitic infections among Southeast Asian labourers in Taiwan: a long-term study

Parasitic infections have been reported to be relatively common among the Southeast Asian labourers in Taiwan. This study, conducted in 1992-6, was designed to determine the temporal changes of the prevalence. Faecal specimens were examined by the formalin-ethyl acetate sedimentation technique and blood samples screened using the quantitative buffy coat technique and confirmed by Giemsa stained blood smear. The overall prevalence of intestinal parasitic infections was 10.3%. The annual prevalence decreased from 33.3% in 1992-3 to 4.6% in 1995-6. The Thai (12.0%) and Indonesian (11.1%) had a higher prevalence than the Malaysian (6.7%) and Filipinos (5.9%). Opisthorchis viverrini was the most important parasite in the Thai and Trichuris trichiura in the remaining groups. Moreover, no blood parasites were found in the labourers. The dramatic temporal decline in the intestinal parasitic infections suggests that limiting the entry of infected persons, periodic follow-ups, and immediate treatment of sporadic cases are necessary in preventing transmission of non-indigenous parasites through large population change.

A modular neural network vector predictor for predictive image coding

In this paper, we present a modular neural network vector predictor that improves the predictive component of a predictive vector quantization (PVQ) scheme. The proposed vector prediction technique consists of five dedicated predictors (experts), where each expert predictor is optimized for a particular class of input vectors. An input vector is classified into one of five classes, based on its directional variances. One expert predictor is optimized for stationary blocks, and each of the other four expert predictors are optimized to predict horizontal, vertical, 45 degrees , and 135 degrees diagonally oriented edge-blocks, respectively. An integrating unit is then used to select or combine the outputs of the experts in order to form the final output of the modular network. Therefore, no side information is transmitted to the receiver about the selected predictor or the integration of the predictors. Experimental results show that the proposed scheme gives an improvement of 1.7 dB over a single multilayer perceptron (MLP) predictor. Furthermore, if the information about the predictor selection is sent to the receiver, the improvement could be up to 3 dB over a single MLP predictor. The perceptual quality of the predicted images is also significantly improved.

Automatic target recognition using a feature-decomposition and data-decomposition modular neural network

A modular neural network classifier has been applied to the problem of automatic target recognition using forward-looking infrared (FLIR) imagery. The classifier consists of several independently trained neural networks. Each neural network makes a decision based on local features extracted from a specific portion of a target image. The classification decisions of the individual networks are combined to determine the final classification. Experiments show that decomposition of the input features results in performance superior to a fully connected network in terms of both network complexity and probability of classification. Performance of the classifier is further improved by the use of multiresolution features and by the introduction of a higher level neural network on the top of the individual networks, a method known as stacked generalization. In addition to feature decomposition, we implemented a data-decomposition classifier network and demonstrated improved performance. Experimental results are reported on a large set of real FLIR images.

Comparison of a whole-blood agglutination test and an ELISA for the detection of the antigens of Dirofilaria immitis in dogs

To compare the usefulness of two commercial tests for detecting the antigens of Dirofilaria immitis in dogs, one based on whole-blood agglutination (WBA) and the other on ELISA, 100 stray dogs from North Taiwan were tested before necropsy. Of the 53 dogs found to contain D. immitis at necropsy, which had a mean (S.D.) burden of 8.2 (10.6) worms/dog, 45 were found to be positive by WBA and 47 by ELISA. All the false negatives were dogs with very low worm burdens. Although the ELISA was more sensitive (83.9% v. 71.7%) and specific (100% v. 85.1%) than the WBA, the latter is simpler to use and less time-consuming. In terms of their general use for diagnosis of canine heartworm, there seems little to choose between the two tests. The false negatives observed with both tests are not likely to be a problem as they represent dogs with worm burdens which are probably too low to cause significant clinical manifestations or pathology. As the positive predictive value of the WBA test declines dramatically with prevalence of infection, this test may not be suitable for detecting D. immitis in canine populations in which heartworm infection is rare.

Canine filarial infections in north Taiwan

To assess the current status of Dirofilaria immitis infection and to determine whether there were other canine filarial infections in north Taiwan, postmortem examination was conducted in 180 stray dogs more than 12 months old. Blood and serum samples were examined using a modified Knott's test and an antigen-detecting enzyme-linked immunosorbent assay (ELISA) kit, respectively. Filarial infection was found in 60.6% of the dogs: 55% with D. immitis and 12.2% Dipetalonema reconditum. Moreover, the ELISA was determined to be more sensitive than the Knott's test. Although canine heartworm infection in Taiwan has been attributed to the unrestricted import of dogs from endemic areas, the results of this study indicate that transmission of D. immitis and Dip. reconditum may occur indigenously in the local canine population. This study is also the first record of Dip. reconditum in Taiwan.

[Receptors of monoamine in sympathetic preganglionic neurons of neonatal rat spinal cord in vitro]

By means of intracellular recordings from spinal cord slices of neonatal rats in vitro, the effects of 5-hydroxytryptamine (5-HT), nor-adrenaline (NA) and adrenaline (AD) on membrane potential in sympathetic preganglionic neurons (SPN) were observed, in order to clarify whether these neuron contain a single type of the monoamine receptor or in combination with more than one type of receptors. The results showed that: (1) 5-HT, NA and AD induced membrane depolarization respectively in 57.1% (16/28), 60% (15/25) and 52.4% (11/21) of SPN. (2) According to the reactions of SPN to the three monoamines, several subtypes of SPN could be divided: those sensitive to all the three monoamines (3/19), those sensitive to two of them (9/19), those only sensitive to one type of monoamines (4/19) and those insensitive at all (3/19). The significance of coexistence of more than one type of the three monoamines in a single neuron remains to be elucidated.

Yolk sac angiogenic defect and intra-embryonic apoptosis in mice lacking the Ets-related factor TEL

The TEL gene, which is frequently rearranged in human leukemias of both myeloid and lymphoid origin, encodes a member of the Ets family of transcription factors. The TEL gene is widely expressed throughout embryonic development and in the adult. To determine the requirement for the TEL gene product in development we generated TEL knockout mice (TEL-/-) by gene targeting in embryonic stem cells. TEL-/- mice are embryonic lethal and die between E10.5-11.5 with defective yolk sac angiogenesis and intra-embryonic apoptosis of mesenchymal and neural cells. Two-thirds of TEL-deficient yolk sacs at E9.5 lack vitelline vessels, yet possess capillaries, indicative of normal vasculogenesis. Vitelline vessels regress by E10.5 in the remaining TEL-/- yolk sacs. Hematopoiesis at the yolk sac stage, however, appears unaffected in TEL-/- embryos. Our findings demonstrate that TEL is required for maintenance of the developing vascular network in the yolk sac and for survival of selected cell types within the embryo proper.

Polyunsaturated fat in the diet may improve intestinal function in patients with Crohn's disease

To investigate the effect of increasing dietary polyunsaturated fat intake on fat absorption in Crohn's patients, normal subjects and subjects with inactive Crohn's disease consumed a high polyunsaturated to saturated fat ratio diet. Subjects participated in breath tests before and after six months of a high polyunsaturated to saturated (P/S) fat ratio diet to measure their response to [1-13C] 10:0 and [1-13C] 16:0 ingested with a test meal. Whole body absorption-oxidation of C10:0 was not affected by the diet treatment. Before diet treatment, whole body absorption-oxidation of C16:0 in Crohn's patients was 80% of that observed for control subjects. After consuming a high polyunsaturated to saturated fatty acid ratio diet, subjects increased oxidation of C16:0 by 85% compared to before the diet treatment period. It is concluded that (1) absorption of labelled C16:0 from a test meal is reduced in Crohn's patients, and (2) consumption of a high polyunsaturated to saturated fatty acid ratio diet improves the utilization of dietary C16:0 by Crohn's patients.

Effects of hypothermia on energy metabolism in rat and Richardson's ground squirrel hearts

Glycolysis, glucose oxidation, palmitate oxidation, and cardiac function were measured in isolated working hearts from ground squirrels and rats subjected to a hypothermia-rewarming protocol. Hearts were perfused initially for 30 min at 37 degrees C, followed by 2 h of hypothermic perfusion at 15 degrees C, after which hearts were rewarmed to 37 degrees C and further perfused for 30 min. Functional recovery in ground squirrel hearts was greater than in rat hearts after rewarming. Hypothermia-rewarming had a similar general effect on the various metabolic pathways in both species. Despite these similarities, total energy substrate metabolic rates were greater in rat than ground squirrel hearts during hypothermia despite a lower level of work being performed by the rat hearts, indicating that rat hearts are less efficient than ground squirrel hearts during hypothermia. After rewarming, energy substrate metabolism recovered completely in both species, although cardiac work remained depressed in rat hearts. The difference in functional recovery between rat and ground squirrel hearts after rewarming cannot be explained by general differences in energy substrate metabolism during hypothermia or after rewarming.