High extracellular potassium modulates nitric oxide synthase expression in human astrocytes

Inducible nitric oxide synthase (iNOS) is a molecule of great interest, given the numerous biological activities of nitric oxide and the documented expression of iNOS in several CNS pathologies. There also appears to be species-dependent regulation of iNOS expression as well as CNS-specific regulation. In this study, we have examined cultures of cytokine-activated primary human astrocytes as a model system with which to study the mechanisms of iNOS regulation in human CNS. As one of the major functions of astrocytes is spatial buffering of K+ ion, we examined the effect of high extracellular KCI on astrocyte iNOS expression. The results demonstrate that KCI at 25-75 mM potently inhibits astrocyte nitrite production stimulated by interleukin-1 (IL-1)/interferon-gamma (IFNgamma). In addition, several potassium channel inhibitors such as CsCl, tetraethylammonium, and 4-aminopyridine as well as nigericin inhibited astrocyte iNOS expression induced by IL-1/IFNgamma. These results demonstrate a novel role for astrocyte potassium channel activity in modulation of astrocyte function. They further suggest neural-specific mechanisms for glial iNOS regulation.

Identification of a major cluster of Klebsiella pneumoniae isolates from patients with liver abscess in Taiwan

Klebsiella pneumoniae has emerged as the leading liver abscess pathogen in Taiwan, with the percentage rising from 30% in the 1980s to over 80% in the 1990s. Most of the patients with K. pneumoniae liver abscess are diabetic and without biliary tract disease. Some patients develop serious extrahepatic complications such as endophthalmitis, meningitis, lung abscess, and necrotizing fasciitis. Pulsed-field gel electrophoresis (PFGE) was used for cluster analysis of 96 isolates from patients with liver abscess and 60 isolates from patients with other diseases. A total of 136 PFGE types were identified. Among the 96 liver abscess-associated isolates, 60 (62.5%) were classified in major cluster A. Cluster A included 41 PFGE types (types 1 to 41) which had a genetic similarity of at least 72.4% +/- 9.4%. The PFGE patterns of cluster A strains are so similar that they could have originated from the same ancestor. This study demonstrates that cluster A plays an important role in the high incidence of K. pneumoniae liver abscess in Taiwan.

Recognition of handwritten similar Chinese characters by self-growing probabilistic decision-based neural network

Recognition of similar (confusion) characters is a difficult problem in optical character recognition (OCR). In this paper, we introduce a neural network solution that is capable of modeling minor differences among similar characters, and is robust to various personal handwriting styles. The Self-growing Probabilistic Decision-based Neural Network (SPDNN) is a probabilistic type neural network, which adopts a hierarchical network structure with nonlinear basis functions and a competitive credit-assignment scheme. Based on the SPDNN model, we have constructed a three-stage recognition system. First, a coarse classifier determines a character to be input to one of the pre-defined subclasses partitioned from a large character set, such as Chinese mixed with alphanumerics. Then a character recognizer determines the input image which best matches the reference character in the subclass. Lastly, the third module is a similar character recognizer, which can further enhance the recognition accuracy among similar or confusing characters. The prototype system has demonstrated a successful application of SPDNN to similar handwritten Chinese recognition for the public database CCL/HCCR1 (5401 characters x200 samples). Regarding performance, experiments on the CCL/HCCR1 database produced 90.12% recognition accuracy with no rejection, and 94.11% accuracy with 6.7% rejection, respectively. This recognition accuracy represents about 4% improvement on the previously announced performance. As to processing speed, processing before recognition (including image preprocessing, segmentation, and feature extraction) requires about one second for an A4 size character image, and recognition consumes approximately 0.27 second per character on a Pentium-100 based personal computer, without use of any hardware accelerator or co-processor.

Varicella pneumonia complicated by acute respiratory distress syndrome in an adult

Primary varicella infection is uncommon in adults, but carries a higher rate of morbidity and mortality than in children. Pneumonia is the most common complication of primary varicella infection in adults. However, varicella pneumonia complicated with acute respiratory distress syndrome (ARDS) is very rare. We report a case of ARDS secondary to varicella pneumonia in a 26-year-old man with primary varicella. The patient was otherwise healthy and had no evidence of human immunodeficiency virus infection. The initial chest radiograph showed bilateral reticulonodular infiltrates, which quickly evolved to diffuse alveolar consolidations. Arterial blood gas analysis revealed a ratio of arterial partial pressure to fraction of inspired oxygen of 87. Abnormal liver function and thrombocytopenia were also noted. Treatment consisted of mechanical ventilatory support and intravenous administration of acyclovir. His pulmonary condition gradually improved and he was successfully weaned from the ventilator 1 week later. He was discharged on the 15th hospital day with a favorable outcome. His pulmonary function improved progressively, with normal spirometry and lung volumes, but persistent mild impairment of diffusing capacity, 6 months after discharge.

Lysophosphatidic acid, alkylglycerophosphate and alkylacetylglycerophosphate increase the neuronal nuclear acetylation of 1-acyl lysophosphatidyl choline by inhibition of lysophospholipase

Neuronal nuclei were isolated from rabbit cerebral cortex, and lipid acetylation reactions were studied because of the high nuclear concentration of acetyltransferases that generate platelet activating factor (PAF) and its acyl analogue AcylPAF. The neuronal nuclear acetylation of 1-palmitoyl lysophosphatidylcholine (lyso PC) was found to be increased more than twofold when low concentrations of lyso PC were incubated in acetylation assays in the presence of 1-palmitoyl lysophosphatidic acid (lyso PA) or 1-hexadecyl glycerophosphate (AGP). This effect was not found for a variety of other acidic and neutral 1-acyl lysoglycerophospholipids. At 4 microM concentrations, AGP was the more effective in increasing rates of lyso PC acetylation, while lyso PA was more effective at 25-35 microM. 1-Stearoyl, 1-alkenyl and 1-decanoyl analogues of lyso PA were all less effective than 1-palmitoyl lyso PA. Phosphatidic acid was considerably less effective than lyso PA, while the acetylated analogue of AGP, AAcGP (alkylacetylglycerophosphate), increased rates of lyso PC acetylation to maxima similar to those seen with lyso PA or AGP. In addition, AAcGP promoted these maxima at considerably lower concentrations (2-4 microM). A mechanism for these effects was suggested when nuclear envelopes (NE), isolated in the presence of PMSF, showed these maximal acetylation rates at low lyso PC concentrations, and these rates were not elevated by the presence of lyso PA. PMSF is a protease inhibitor but can also inhibit lysophospholipase activity. We found a nuclear lysophospholipase that degraded lyso PC at rates more than 13 times those of nuclear lyso PC acetylation. PMSF did inhibit this nuclear lysophospholipase, as did lyso PA, AGP and AAcGP. Kinetic analyses of the effects of lyso PA, AGP and AAcGP on lyso PC lysophospholipase indicated that these three lipids acted as competitive inhibitors for the lyso PC substrate. It is possible that low rates of lyso PC acetylation seen in neuronal nuclei at low lyso PC concentrations, are caused by lyso PC loss mediated by a very strong nuclear lysophospholipase. The effects of lyso PA, AGP and AAcGP in boosting rates of lyso PC acetylation likely come from the inhibition of nuclear lysophospholipase and a preservation of lyso PC concentrations. Competing neuronal nuclear reactions for low endogenous levels of lyso PC may regulate the formation of AcylPAF, and rising lyso PA, AGP or AAcGP concentrations can increase rates of nuclear AcylPAF synthesis.

Time course of pharmacological modulation of peak eosinophilic airway inflammation after mite challenge in guinea pigs: a therapeutic approach

BACKGROUND

It is well known that eosinophilic airway inflammation develops after allergen challenge in sensitized humans and animals. However, the detailed time course of suppression of early eosinophilic airway inflammation by pharmacological agents given just after challenge has not been discussed. Therefore, we aimed to evaluate the time course relationship of the suppression of peak eosinophilia by anti-cytokines and pharmacological agents given several hours after the aerosol challenge by a therapeutic approach.

METHODS

We used crude mite extract as an allergen to create a sensitization and inhalation challenge, and performed bronchoalveolar lavages (BAL) after the inhalation challenge to observe the degree of eosinophilic airway inflammation in guinea pigs. Various anti-cytokines (anti-IL-3 and anti-IL-5) and pharmacological agents (dexamethasone, theophylline, and roxithromycin) were given within several hours after the acute aeorosol challenge to evaluate the suppressive effect on peak eosinophilia in BAL fluid, which occurred 24 h after the challenge.

RESULTS

Our results show that anti-IL-5 and dexamethasone, given within 4 and 8 h after the inhalation challenge, respectively, inhibit the acute allergen-induced peak eosinophilia in BAL fluid. However, anti-IL-3, theophylline, and roxithromycin had no effect on peak eosinophilic airway inflammation after challenge.

CONCLUSION

These observations suggest that several hours are needed to complete the process of cytokine-induced recruitment of eosinophils from the blood to the airways after acute allergen challenge. This may be the optimal time to administer anti-cytokines and dexamethasone to attenuate the subsequent eosinophilic airway inflammation after acute allergen-induced asthmatic attacks.

Effects of N(omega)-nitro-L-arginine (L-NOARG) on blood flow and vasomotion in rat diaphragm microcirculation during hemorrhagic hypotension

The role of N(omega)-nitro-L-arginine (L-NOARG), a nitric oxide (NO) synthase inhibitor, in the control of blood flow and vasomotion in rat diaphragm microcirculation during hemorrhagic hypotension was investigated by means of laser Doppler flowmetry (LDF). Fifty-six Sprague-Dawley rats were divided into seven groups. Ten minutes after one-stage hemorrhage to 40-60% of initial blood pressure, the rats received 15 min topical superfusion of saline (group 1, time control), 0.1 mM L-NOARG (group 2), 10 mM L-arginine (group 3), or vehicle (0.1% DMSO and 0.9 mN NaOH, group 4). For groups 5 and 6, L-NOARG or its vehicle was superfused for 15 min without hemorrhage. In group 7, the vasodilator responses to the endothelium-dependent vasorelaxant acetylcholine (ACH) and the endothelium-independent vasorelaxant sodium nitroprusside (SNP) were assessed at rest and after 25 min of hemorrhagic hypotension. The results showed no significant differences in blood flow, fundamental frequency, or relative amplitude of the rat diaphragm microcirculation before or after administration of the test agents among the first four groups during hemorrhagic hypotension or in groups 5 and 6 during sham operation without hypoperfusion. Hemorrhagic hypotension significantly decreased the vasodilator response to ACH (p = 0.003), but not to SNP. We conclude that NO did not play an important role in the regulation of blood flow or vasomotion in rat diaphragm microcirculation during acute hemorrhagic hypotension.

Stepwise chromosome evolution in Drosophila albomicans

A 'stepwise chromosome evolution model' is proposed to elaborate the two stages of the sex chromosome evolution of Drosophila albomicans. To explain the occurrence of both a 3-X and a 3-Y in this species it is proposed that these chromosomes evolved sequentially. The selection forces acting in the two stages are different. The genic composition in the first fused sex chromosome of D. albomicans was supposed to be selectively superior to the primitive unfused chromosomes, thus the fused chromosome could overcome the meiotic structural incompatibility and be maintained in the population during the first stage. When the second fusion occurred, the newly fused sex chromosome was preferentially selected, as it could provide a meiotic pairing partner for the first fusion. The fused sex chromosomes were eventually fixed in the population. Based on this model, we tried to determine which fused chromosome, 3-X or 3-Y, established first. The karyotyping result of four experimental hybrid populations showed that the fused 3-X, as opposed to 3-Y, chromosome has higher fitness values. However, without the coexistence of 3-X, 3-Y is excluded rapidly. Therefore, 3-X is likely to be the first fused chromosome in the stepwise chromosome evolution model. The formation and fixation of the fused 3-Y chromosome occurred subsequently.

Optimal design for a study of butadiene toxicokinetics in humans

The derivation of the optimal design for an upcoming toxicokinetic study of butadiene in humans is presented. The specific goal of the planned study is to obtain a precise estimate of butadiene metabolic clearance for each study subject, together with a good characterization of its population variance. We used a two-compartment toxicokinetic model, imbedded in a hierarchical population model of variability, in conjunction with a preliminary set of butadiene kinetic data in humans, as a basis for design optimization. Optimization was performed using Monte Carlo simulations. Candidate designs differed in the number and timing of exhaled air samples to be collected. Simulations indicated that only 10 air samples should be necessary to obtain a coefficient of variation of 15% for the estimated clearance rate, if the timing of those samples is properly chosen. Optimal sampling times were found to closely bracket the end of exposure. This efficient design will allow the recruitment of more subjects in the study, in particular to match prescribed levels of accuracy in the estimate of the population variance of the butadiene metabolic rate constant. The techniques presented here have general applicability to the design of human and animal toxicology studies.

Evidence for two distinct lysophospholipase activities that degrade lysophosphatidylcholine and lysophosphatidic acid in neuronal nuclei of cerebral cortex

Neuronal nuclei were isolated from immature rabbit cerebral cortex and nuclear lysophospholipase activities studied using two different 1-acyl lysophospholipids: lysophosphatidylcholine (lysoPC) and lysophosphatidic acid (lysoPA). Our interest in these two lysolipids arose from the observation that lysoPA could promote the acetylation of lysoPC by substantially inhibiting a very active nuclear lysoPC lysophospholipase activity, in a competitive manner (R.R. Baker, H. -y. Chang, Mol. Cell. Biochem. (1999) in press). As there was also evidence for nuclear lysoPA deacylation, it was of interest to see whether one activity could possibly utilize both lysolipid substrates. We now have evidence for two separate lysophospholipase activities in neuronal nuclei. The lysoPC lysophospholipase activity was the more active, more highly enriched in the neuronal nuclei, and showed optimal activity at pH 8.4-9, while the lysoPA lysophospholipase activity was maintained over a much broader pH range. The lysoPC activity was substantially inhibited by free fatty acid, and showed considerable stimulation by serum albumin, while the activity utilizing lysoPA was much less affected by these agents. When lysoPC was added to incubations containing radioactive lysoPA, there was no significant inhibition found in rates of release of radioactive fatty acid, indicating that the lysoPA lysophospholipase activity did not utilize the lysoPC substrate. In incubations with lysoPC, MgATP and CoA brought about a sizable formation of phosphatidylcholine whose radioactivity was equally distributed between the sn-1 and sn-2 positions suggesting labelling both directly from the lysoPC substrate and from fatty acid produced by the lysophospholipase activity. By comparison, with the radioactive lysoPA substrate, MgATP and CoA promoted relatively lower levels of phosphatidic acid formation whose principal labelling came directly from the radioactive lysoPA. Largely because of the high activity of the nuclear lysoPC lysophospholipase, there is considerable potential in the neuronal nucleus to limit the use of lysoPC in other reactions, such as the formation of acylPAF (1-acyl analogue of platelet activating factor). It is of interest that conditions associated with brain ischaemia such as increased free fatty acid levels, falling pH and declines in MgATP may allow a preservation of neuronal nuclear lysoPC levels for acetylation. The existence of a separate lysophospholipase activity for lysoPA allows an independent control of lysoPA which can serve as an important regulator of the nuclear lysoPC lysophospholipase.

Risk assessment of lung cancer and mesothelioma in people living near asbestos-related factories in Taiwan

Estimates from environmental risk assessments are criticized by professionals who indicate that inaccuracies occur in exposure assessment, model selection, and determination of the population at risk. In the current study, we tackled the aforementioned issues and estimated the risks of lung cancer and mesothelioma caused by airborne asbestos among individuals who lived near asbestos factories in Taiwan. We conducted 8-h full-period samplings upwind and downwind from each factory, and we used transmission-electronic microscopy (10,000x) and phase-contrast microscopy to determine asbestos concentrations in and around each factory. We estimated the numbers of residents who lived in concentric circles of 200-m, 400-m, and 600-m diameters around each factory. A dose-response model for asbestos-induced lung cancer was adopted from a summary of seven epidemiological studies. The asbestos-mesothelioma models were patterned after the first-exposure-effect models developed by Peto and Finkelstein. The data obtained from phase-contrast microscopy significantly overestimated the risk, compared with transmission-electronic microscopy. The estimates we calculated from adopting the arithmetic mean were approximately 2-fold higher than those we calculated with the geometric mean. There were relatively low concentrations of asbestos in the study areas, thus causing an absence of a significant difference in risk estimates between different models for mesothelioma. Among the more than 20,000 residents who lived near 41 asbestos factories in Taiwan, we found that the numbers of expected excess deaths from lung cancer and mesothelioma were 5 and less than 1, respectively. We concluded that in future risk assessments for ambient asbestos exposure, investigators should adopt transmission-electronic microscopy and the geometric mean estimate. Moreover, Taiwan should enhance asbestos-control programs to assure the safety of residents who live near asbestos factories.

Acute and chronic phase platelet aggregability studies in Chinese patients after implantation of a permanent transvenous pacemaker

It has been suggested that the incidence of thromboembolic events always increases in patients after insertion of a transvenous pacemaker. Blood samples from twenty consecutive patients (fifteen males and five females) before and after pacemaker implantation was retained for platelet aggregability studies which were analyzed separately with ADP, collagen, epinephrine and arachidonic acid. The maximal amplitude of platelet aggregatory curve was detected by an aggregometer. The samples collected the day before pacemaker implantation (day 0) were used as self-control. Day 1 and day 3 after pacemaker implantation were defined as the acute phase, while day 30 was defined as the chronic phase. The maximal amplitude of platelet aggregatory curve was observed to be lowest on day 1 and then return to normal on day 3 and day 30. The results of platelet aggregability, however, showed no significant difference (P>0.05) between self-control and post-implantation samples. In conclusion, there was no significant change in platelet aggregability for either acute or chronic phases after pacemaker implantation. Antiplatelet medications may not be necessary for the prevention of thromboembolic events after the implantation of a pacemaker.

Characterization of a putative Pseudomonas UDPglucose pyrophosphorylase

A UDP-glucose pyrophosphorylase encoding gene was identified through functional complementation screening by using an Escherichia coli galU mutant. Sequence analysis of the gene indicated that it is most likely derived from a Pseud monas sp. The gene is located immediately upstream and transcribed in the same direction of the gor (glutathione reductase) gene and is capable of encoding a protein 30,943 daltons in size. The gene product synthesized in Escherichia coli was purified and its biochemical properties characterized. The recombinant UDP-glucose pyrophosphorylase exhibited a molecular weight of 130 kDa, suggesting a tetrameric organization of the gene product. Two mutant forms of the enzyme were identified. The activity of the mutant enzyme with a tyrosine to histidine (Y26 1H) substitution was found to be greatly reduced. On the other hand, the tyrosine to cysteine (Y84C) substitution resulted in an enzyme that functions normally at 37 degrees C but rather poorly at temperatures lower than 30 degrees C.

Characterization of mdcR, a regulatory gene of the malonate catabolic system in Klebsiella pneumoniae

The Klebsiella pneumoniae mdcR gene, which encodes a LysR-type regulator, was overexpressed in Escherichia coli. Purified MdcR was found to bind specifically to the control region of either the malonate decarboxylase (mdc) genes or mdcR. We have also demonstrated that MdcR is an activator of the expression of the mdc genes, whereas it represses the transcription of the putative control region of mdcR, PmdcR, indicating a negative autoregulatory control.

Predicting factors for outcome of tube thoracostomy in complicated parapneumonic effusion for empyema

STUDY OBJECTIVES

To determine the predicting factors for outcome of tube thoracostomy in patients with complicated parapneumonic effusion (CPE) or empyema.

DESIGN AND SETTINGS

Retrospective chart review over a 55-month period at a tertiary referred medical center.

PATIENTS AND MEASUREMENTS

The medical charts of patients with empyema or CPE were reviewed. Data including age, gender, clinical symptoms, important underlying diseases, leukocyte count, duration of preadmission symptoms, interval from first procedure to second procedure, the time from first procedure to discharge (recovery time), the amount of effusion drained, administration of intrapleural streptokinase, chest tube size and position, loculation of pleural effusion, and characteristics and culture results of pleural effusion were recorded and compared between groups of patients with successful and failed outcome of tube thoracostomy drainage.

RESULTS

One hundred twenty-one patients were selected for study. One hundred of these patients had received tube thoracostomy drainage with 53 successful outcomes and 47 failed outcomes of chest tube drainage. Nineteen patients received decortication directly, and the other two received antibiotics alone. Univariate analysis showed that pleural effusion leukocyte count, effusion amount, and loculation of pleural effusion were significantly related to the outcome of chest tube drainage. Multiple logistic regression analysis demonstrated that loculation and pleural effusion leukocyte count < or = 6,400/uL were the only independent predicting factors related to failure of tube thoracostomy drainage.

CONCLUSIONS

Loculation and pleural effusion leukocyte count < or = 6,400/microL were independent predicting factors of poor outcome of tube thoracostomy drainage. These results suggest that if the initial attempt at chest tube drainage fails, early surgical intervention should be considered in good surgical candidates with loculated empyema or pleural effusion with leukocyte count < or = 6,400/microL.

Outbreak of Candida parapsilosis fungemia in neonatal intensive care units: clinical implications and genotyping analysis

During a 5-month period, 17 infants hospitalized in neonatal intensive care units of a medical center and a branch hospital developed 18 episodes of Candida parapsilosis fungemia. The mean age at onset was 35 days. Prior to fungemia, all the infants had received hyperalimentation and antibiotics, and 15 infants had had central venous catheters. The presenting symptoms were variable but only vague in 40% of the episodes. Despite administration of antifungal agents, subsequent eradication of fungemia was achieved in only two-thirds of the episodes. None of the environmental samples was positive for C. parapsilosis, while 20% of hand-washing samples of staff working in both units yielded this microorganism. Four genotypes with two main types were identified from 14 outbreak strains and eight genotypes from 14 hand-washing strains, with one type predominant. The results suggest that C. parapsilosis fungemia increases the morbidity and mortality of neonates but does not cause acute lethal events. The outbreak was caused by two main genotypes, possibly via cross-infection by the hands of health care workers.

Dissecting Fas signaling with an altered-specificity death-domain mutant: requirement of FADD binding for apoptosis but not Jun N-terminal kinase activation

Fas is a cell surface death receptor that regulates peripheral tolerance and lymphoid homeostasis. In many pathologic conditions, ectopic Fas activation mediates tissue destruction. Several proteins that can bind to the cytoplasmic death domain of Fas have been implicated in Fas signal transduction. Here we show that FADD, which couples Fas to pro-caspase-8, and, Daxx, which couples Fas to the Jun N-terminal kinase pathway, bind independently to the Fas death domain. We have isolated a death domain mutant, termed FasDelta, that selectively binds Daxx but not FADD. In tranfected tissue culture cells, FasDelta activated Jun N-terminal kinase normally but was impaired in cell death induction. These results suggest that FADD and Daxx activate two independent pathways downstream of Fas and confirm the essential role of FADD binding in apoptosis induction.

Applications of an acute assessment methodology used for combustion facilities

Two approaches for evaluating potential health impact from short-term (1 hour) inhalation exposure to air emissions from combustion facilities are presented. This information was included as part of the health risk assessment (HRA) conducted for each proposed facility in conjunction with regulatory requirements for obtaining an operating permit. Since the facilities being evaluated have either not yet been constructed or are not yet operational, air concentrations (particulate and vapor) must first be estimated using data from similar and operational facilities. A chemical's modeled air concentration was then compared to its acute toxicity value (ATV) selected from established Occupational Exposure Limits (OEL) or acute toxicity databases, if available. Analogous to the current USEPA approach for estimating noncancer health effects, acute hazard quotients (AHQs) were summed and compared to a level of one. When the summation of the AHQs exceeded unity, the chemicals were separated by target organ and health effects based on acute exposures. The author recognizes that the use of OELs has its limitations. However, due to the lack of acute toxicity data and the advantage of the completeness of the databases for OELs, this approach may be the best way to evaluate for acute health concerns for the more than 70 compounds that may be emitted from these facilities.

Natural mass infection by heterophyid metacercariae in aquacultured Japanese eel in Taiwan

A natural mass infection of heterophyid metacercariae in aquacultured Japanese eel Anguilla japonica in Taiwan was observed. Of the 28,000 adult eels in 2 ponds, about 25,000 (90%) showed swollen, cloudy and white eyes. Although morbidity was about 90%, there was no mortality among the affected eels. Histopathological sections showed edema and hemorrhage of the eye. Numerous metacercariae were observed in the muscle tissues around the eyeball, the subcutaneous tissue and even in the cartilage. Of the 6 eels digested with artificial gastric juice, all were found to contain metacercariae in their muscle tissues. The average number of metacercariae recovered from the 6 eels was 1219, with a range of 50 to 3762. These metacercariae, when fed orally to immunodeficient (scid) mice, developed into adult worms which were identified as Procerovum cheni Hsu 1950. The naturally infected eels were transferred to a new pond without snails and their eye lesions were not apparent anymore after 2 wk. In a follow-up investigation, 19 of 20 apparently healthy eels in a nearby aquaculture farm were found to harbour metacercariae in their muscles. However, the number of the metacercariae ranged from 1 to 14, with an average of 4.21. This is the first report of heterophyid metacercariae causing mass morbidity in aquacultured eels.

Identification of a novel family of human Rab-like small GTP-binding proteins

The presence of a novel family of Rab-like proteins (Rlp) in the human genome is reported. The gene encoding the Rlp-2 was isolated from a human lymphocyte genomic library. The Rlp-2 gene is intronless and was mapped to chromosome Xq21.3 using fluorescence in situ hybridization. Several cDNA clones encoding the Rlp-1 were identified in a human hippocampus lambda library. Northern analysis revealed a 2.1-kb transcript of Rlp-1 expressed predominantly in brain, heart and skeletal muscle. The transcript was also observed in all examined regions of the human brain at a similar level. An additional gene, termed Rlp-3, which is highly related to Rlp-1 and Rlp-2, was found in the GenBank Data Base. The predicted molecular mass for Rlp is approximately 31 kDa and is consistent with that of Rlp-1 synthesized in Escherichia coli.

Gene transfer via pollen-tube pathway for anti-fusarium wilt in watermelon

In order to obtain transgenic fusarium wilt resistant watermelon plants, squash DNA was introduced into the ovaries of watermelon plants via the pollen-tube pathway. The introduction of foreign genes into ovaries was accomplished using co-transformation with the CaMV35S-GUS as a marker. Transformed watermelon plants contained integrated copies of the GUS activity and the seeds of transformed progeny produced a blue color when stained with 5-bromo-4-chloro-3-indolyl glucuronide, whereas seeds from untransformed control plants did not. Of 200 transformed seedlings, ten were wilt resistant. The presence of the GUS activity in the genome of stable transgenic seedlings was confirmed by Southern blot analysis. Furthermore, the generation of random amplified polymorphic DNA (RAPD) fingerprints using primers with embedded restriction sites showed amplification products unique to these transgenic plants. Primers OPA-1 and OPA-9 gave distinct band patterns of genomic DNA using the polymerase chain reaction.

Blood supply of esophageal stumps

BACKGROUND/AIMS

The purpose of the study was to determine the blood supply of stumps of mobilized esophagus.

METHODOLOGY

Esophageal stumps of five groups of rabbits were studied. The esophageal stumps were dyed via intravenous injection of trypan blue, and were analyzed by color image processing.

RESULTS

The dyed length of the esophageal stump was 7.15+/-0.5 cm in the stomach-connecting group; 4.6+/-0.69 cm in the stomach-connecting with myotomy group; 6.1+/-0.88 cm in the distal stomach-connecting group; 3.0+/-0.47 cm in the neck-connecting group; and, 2.1+/-0.2 cm in the neck-connecting with myotomy group. There was a significant difference in the dyed length between the stomach-connecting and neck-connecting groups (p=0.000), and between the stomach-connecting and stomach-connecting with myotomy groups (p=0.026), but there was no significant difference between the neck-connecting and neck-connecting with myotomy (p=0.094), or the stomach-connecting and distal stomach-connecting groups (p=0.053).

CONCLUSIONS

Stumps of the mobilized esophagus in rabbits, with or without myotomy, exhibit differences in dyed length, depending on the diameter, wall thickness and location of the blood supply in the esophagus.

Effects of mutations in the starch-binding domain of Bacillus macerans cyclodextrin glycosyltransferase

Cyclodextrin glycosyltransferase (CGTase) is an industrially important enzyme that produces cyclodextrins (CD) from starch by intramolecular transglycosylation. CGTase consists of five globular domains labeled A through E. To better understand the role of domain E in CGTase catalysis, we have constructed several mutants of Bacillus macerans CGTase. Removing the entire E domain resulted in an inactive enzyme. Adding six amino acids between domains D and E caused a decrease in activity and thermostability. Replacing domain E with the similar starch-binding domain from Aspergillus awamori glucoamylase I caused a drastic decrease in activity, indicating the necessity of correct alignment of bound substrate. Substituting tyrosine residue 634 (Tyr634) with phenylalanine had very little effect on activity or thermostability. Substituting Tyr634 with glycine resulted in a 25% increase of specific cyclization and starch-hydrolyzing activities compared with that of the wild-type enzyme. The latter mutant was less thermostable. The results of this study indicate that domain E is important for the stability and integrity of B. macerans CGTase.