Bacteremia in patients with hematologic malignancies

The decision regarding the appropriate empirical antibiotic therapy for bacteremia in patients with hematologic malignancies must be individualized in each institution, by taking into account variations in the patterns of microbial isolates and their resistance profiles. Microbial isolates and antibiotic resistance patterns must be taken into account at each hospital. A shift from bacteremia due to infections caused by predominantly gram-negative organisms to predominantly gram-positive organisms in patients with hematologic malignancies has been noted in reports from other countries. We investigated bacterial isolates and their antibiotic sensitivities in patients with hematologic malignancies in the Veterans General Hospital-Taipei. A total of 185 episodes of bacteremia in 140 patients with hematologic malignancies were recorded during the period from 1995 to 1996. Unlike foreign reports, our investigation shows that gram-negative organisms still predominate, accounting for 72.7% of isolates, followed by gram-positive organisms, accounting for 26.3% of isolates, and anaerobes, accounting for 1% of isolates. Escherichia coli was the most commonly isolated organism, accounting for 23.9% of isolates, followed by Klebsiella pneumoniae (18.5%), Pseudomonas aeruginosa (12.2%), Enterobacter cloacae (7.3%), and methicillin-resistant Staphylococcus aureus (7.3%). A high mortality rate was observed in gram-negative bacteremia: 31% for E. coli, 26% for K. pneumoniae, 24% for P. aeruginosa, and 33% for E. cloacae. If methicillin-resistant S. aureus bacteremia occurred, mortality was high (47%). The antibiotic sensitivity profiles of the four most common gram-negative isolates (E. coli, K. pneumoniae, P. aeruginosa, and E. cloacae) indicated that, in our hospital, amikacin with either cefoperazone, ceftazidime, ciprofloxacin, or imipenem, would be an ideal combination for empirical therapy for bacteremia in patients with hematologic malignancies.

Uncoupling protein-1 mRNA expression in obese human subjects: the role of sequence variations at the uncoupling protein-1 gene locus

Uncoupling protein-1 (UCP-1) activity in brown adipose tissue increases thermogenesis, contributes to facultative energy expenditure in humans, and has been implicated in the pathogenesis of rodent obesity. To determine genetic factors controlling UCP-1 expression in humans, we measured intra- and extraperitoneal UCP-1 mRNA abundance levels by a competitive RT-PCR method and compared expression levels with common sequence variations in the beta3-adrenergic receptor gene and the distal UCP-1 gene promoter in obese human subjects. While median and average UCP-1 mRNA levels in both the intra- and extraperitoneal tissue were lower in subjects heterozygous for the Trp64Arg mutation in the beta3-adrenergic receptor gene, this difference was not statistically significant. However, a strong association of intraperitoneal UCP-1 mRNA abundance with the UCP-1 gene polymorphism at -3826 relative to the transcription start site was observed that explained 19.3% of the interindividual variability. The minor allele imparted a dose-dependent reduction on UCP gene expression. The importance of sequence variations at the UCP-1 gene locus as a common source of UCP-1 mRNA abundance variability was supported by allele-specific expression studies utilizing a newly identified polymorphism in exon 2 of the UCP-1 gene that predicts a substitution of alanine by threonine. In four subjects heterozygous for the -3826 polymorphism, the mRNA species transcribed from the wild-type allele accounted for 63+/-6% percent of total intraperitoneal mRNA abundance. In one subject homozygous for the minor promoter allele, wild-type mRNA was also more abundant than variant mRNA. Thus, the UCP-1 polymorphism at -3826 is probably only a marker for a frequent mutation causing reduced mRNA expression.

Separation of amino acid and peptide stereoisomers by nonionic micelle-mediated capillary electrophoresis after chiral derivatization

Enantiomers of amino acids and peptides were derivatized with a fluorescent chiral reagent, 4-(3-isothiocyanatopyrrolidinl-yl)-7-nitro-2,1,3-benzoxadiazole [R-(-)- or S-(+)-NBD-PyNCS] and the resulting diastereomeric derivatives separated by capillary electrophoresis (CE). The CE running buffer consisted of 25 mM acetate buffer (pH 4) and 10 mM of the nonionic surfactant Triton X-100. The excitation maximum of NBD-PyNCS at 480 nm matches the major Ar-ion emission line at 488 nm allowing sensitive laser-induced fluorescence detection with limits of detection around 50 nM. D-Proline and D-aspartate spiked (at 10(-4) M and 10(-5) M concentrations, respectively) into complex biological matrices (rabbit serum and homogenate of Aplysia californica buccal ganglion) are detected without matrix interferences. This method has also been applied to the determination of D- and L-amino acid residues in peptides after acid hydrolysis. Results from the chiral analysis of the naturally-occurring peptide, gramicidin D, are shown.

Local immune responses correlate with presentation and outcome in tuberculosis

Local cellular immune responses may affect presentation and outcome in tuberculosis (TB). To investigate this hypothesis, we performed bronchoalveolar lavage (BAL) on 30 patients with untreated pulmonary tuberculosis and assessed the type of cellular inflammatory response and cytokine production. We then correlated BAL findings and cytokine production with clinical findings. We also performed BAL on a subset of patients to examine changes in cytokine production by BAL cells over time. We found that at presentation patients with less clinically and radiographically advanced TB (smear-negative, noncavitary disease) had a local immune response characterized by a predominance of lymphocytes. Furthermore, BAL cells from these patients secreted interferon (IFNgamma), and not Interleukin-4, suggesting a Th 1-type lymphocytic response. In patients with smear-positive and/or cavitary disease, macrophages or polymorphonuclear leukocytes were the predominant BAL cell type, but with treatment and clinical improvement these patients went on to recruit IFNgamma producing cells to the lung. We conclude that the type of cellular immune response that occurs locally in the lung may affect presentation and outcome in pulmonary TB, and an understanding of the development of this response may lead to insights into pathogenesis and novel therapies for TB.

Urinary homovanillic acid (HVA) and vanillymandelic acid (VMA) in workers exposed to manganese dust

The neurotoxicity of manganese (Mn) is well known, however, the neurochemical effect caused by this metal is less well investigated. In this study, urinary homovanillic acid (HVA) and vanillymandelic acid (VMA), two end products of catecholamine metabolism, were measured in 39 workers chronically exposed to Mn in a manganese smelting plant. The average duration of Mn exposure was 17.4 yr. Nineteen nonexposed workers were also studied. Concentrations of Mn in serum (MnS) and in urine (MnU) were measured by Zeeman graphite furnace atomic absorption spectrophotometry (ZAAS), and HVA and VMA determined by high performance liquid chromatography (HPLC). For Mn-exposed workers, the concentration of MnS was nearly 2.8 times (1.61 +/- 0.16 mg/L vs 0.56 +/- 0.16 mg/L) and MnU about 4.5 times higher (7.62 +/- 0.17 mg/L vs 1.69 +/- 0.16 mg/L) than the nonexposed. Although the geometric mean concentration of HVA in exposed workers was similar to that of the nonexposed (3.09 +/- 1.39 mg/g cre. vs 2.99 +/- 1.40 mg/g cre.), the VMA concentration was significantly higher (3.02 +/- 1.43 mg/g cre. vs 2.49 +/- 1.58 mg/g cre., p = 0.033). Multiple regression analysis showed that although there were no correlations between any of these parameters with the duration of exposure to Mn, both HVA and VMA showed significant correlations with increase in MnS and MnU. These data provide evidence that exposure to Mn was associated with measurable increase in catecholamine metabolites. This finding is compatible with recent observations in laboratory animals that Mn interferes with neurochemical metabolism.

Positive chronotropic actions of parathyroid hormone and parathyroid hormone-related peptide are associated with increases in the current, I(f), and the slope of the pacemaker potential

BACKGROUND

The classic calciotropic hormone parathyroid hormone (PTH) and its paracrine factor parathyroid hormone-related protein (PTHrP) both increase heart rate.

METHODS AND RESULTS

We used standard electrophysiological techniques to study the effects of PTH and PTHrP on isolated rabbit sinus node, isolated canine Purkinje fibers, and disaggregated rabbit sinus node myocytes. Sinus node maximum diastolic potential, activation voltage, and amplitude were unchanged by PTH or PTHrP (P>.05). However, the slope of phase 4 and the automatic rate were increased at PTH and PTHrP > or = 10 nmol/L (P<.05). Comparable results were seen in canine Purkinje fibers. We then used the perforated-patch technique to study the I(f) pacemaker current in sinus node. PTH 12.5 nmol/L and PTHrP 12.5 to 18 nmol/L increased I(f) at -65 mV by 68+/-41% (n=5) and 69+/-50% (n=5), respectively. Actions of both agents were reversible. The increase in I(f) appeared to result from a change in maximal conductance and not a shift in the voltage dependence of activation.

CONCLUSIONS

These observations provide, for the first time, direct electrophysiological support for the chronotropic actions of PTH and PTHrP. They suggest that classic hormones and paracrine factors can have multiple functions and that in the case of PTH and PTHrP, a newly recognized action is to alter automaticity directly.

[Voltage dependence of late Na channel with burst mode in isolated cardiac myocytes]

Patch clamp technique was employed to record single Na channel currents in isolated guinea-pig ventricular myocytes. Burst mode could be elicited by step depolarization and terminates immediately after repolarization. The unitary current of burst mode was not only dependent on Na concentration in the pipettes but also on the test voltage. The open time constant increased as testing voltage becomes more positive. The results from stepwise-depolarization and ramp depolarization experiments showed that the more steps or the faster the upstroke velocity of depolarization used, the more the burst mode would occure.

Uncoupling protein gene: quantification of expression levels in adipose tissues of obese and non-obese humans

The mitochondrial uncoupling protein (UCP), which is exclusively expressed in brown adipose tissue, regulates energy expenditure in rodents but its importance in the energy homeostasis of adult humans is uncertain. To study associations of UCP gene expression with human obesity, we determined, by a competitive reverse transcription-polymerase chain reaction assay, UCP mRNA expression levels in intra- and extraperitoneal adipose tissues of 79 obese subjects and 17 lean controls. UCP mRNA and internal standard RNA were reverse transcribed and coamplified in one reaction in which the same primers were used. The signal intensities of UCP mRNA products were compared with the signal intensities of standard RNA products to quantify UCP mRNA abundance. UCP mRNA was detected in all intra- and extraperitoneal adipose tissues studied. In both obese and non-obese subjects, UCP mRNA abundance was higher in the intraperitoneal than in the extraperitoneal tissue (P < 0.001). Compared to lean controls, morbidly obese subjects showed a significantly lower age- and gender-adjusted UCP mRNA expression level in the intraperitoneal adipose tissue (3.467 +/- 2.483 vs. 6.917 +/- 4.292 amol/fmol beta-actin mRNA; mean +/- SD, P < 0.002), while UCP mRNA abundance in extraperitoneal adipose tissue did not differ between obese and nonobese subjects. These data are consistent with reduced energy expenditure in obesity, but it remains to be determined whether the association of decreased intraperitoneal UCP mRNA expression with obesity status reflects a causal contribution of brown adipose tissue function to the pathogenesis of obesity.

[Selection of location for transcutaneous bilirubinometry in light therapy]

64 jaundiced neonates were measured with transcutaneous bilirubinometer for the jaundice index on the forehead and superciliary narch where was covered during photo therapy respectively. The result showed that the jaundice index in the uncovered place decreased greatly after the therapy was over, but the index went up again 12 hours later. The index on the covered place did not show this change. It is suggested that the covered place is a better site for measuring jaundice index because it can avoid the effect of phototherapy on the measuring result and make the result more accurate.

Four types of late Na channel current in isolated ventricular myocytes with reference to their contribution to the lastingness of action potential plateau

Patch clamp technique was employed to record single Na channel current in isolated guinea-pig ventricular myocytes. Four types of late Na channel currents were observed with whole cell and inside-out recording, which are (1) isolated brief openings, (2) scattered openings, (3) long openings and (4) bursts. The occurrence frequencies of the four types were different. Bursts appeared about 1 in every 2,000 depolarizations, with an open time constant longer than others. However, all the four types of late current openings, as well as the early openings occurring immediately upon depolarization, could be blocked by tetrodotoxin. It was also found that at a certain stimulation frequency, normal action potential duration (APD) was not invariable as supposed before, but varied from stimulation to stimulation. Special Na channel blocker, TTX, shortened the APD and refractory period and abolished the dispersion. The above results suggest that the activities of the various types of late Na channel play an important role in the formation of action potential plateau.

Two-dimensional separations: capillary electrophoresis coupled to channel gel electrophoresis

Two-dimensional separations provide extremely high peak capacities. Coupling capillary zone electrophoresis with ultrathin channel gel electrophoresis offers a convenient and efficient way to perform such two-dimensional microseparations. By means of in situ polymerization, high-concentration (up to 50%T) polyacrylamide gels are prepared in 75 mm long, 25 mm wide, and 40 microns thick rectangular channels. By moving the outlet end of the capillary electrophoresis capillary across the entrance of the channel, both separations are completely preserved. Mixtures of peptides labeled by fluorescein isothiocyanate (FITC) are well resolved in less than 15 min, with theoretical plate numbers in the range of 20,000-50,000 for each independent separation. Significant enhancement in separation efficiency and peak capacity over one-dimensional separations are demonstrated by this combination. The two-dimensional separations of a model mixture of peptides, a tryptic digest of trypsinogen, and < 0.05% of an individual B2 neuron from the marine mollusk Aplysia californica are presented.

Channel electrophoresis for kinetic assays

A rectangular channel electrophoresis system and a cylindrical sampling capillary combination allows chemical changes in nanoliter-volume samples to be monitored as a function of time. The electrophoretic microseparation is carried out in a rectangular channel with a 7 -cm-long, 40-microm x 2.5-cm geometry and is coupled to a 50-microm-i.d. cylindrical sample introduction capillary. The channel width dimension is used as a time axis by moving the outlet of the sampling capillary across the entrance of the separation channel. Detection of the separated analyte bands is achieved with laser-induced fluorescence and spatially resolved detection based on a charge-coupled device. The system is characterized with a series of fluorescein thiocarbamyl amino acid derivatives; limits of detection are < 10(-8) M for amino acids and 10(-9)M (425 zmol) for fluorescein. The ability to achieve a time-based dynamic microseparation is demonstrated by monitoring fluorescent product formation during the enzyme-catalyzed hydrolysis of fluorescein di-beta-D-galactopyranoside (FDG), a commonly used fluorescent substrate for enzymological studies.

[Clinical research of the bushen tiaojing decotion in promoting ovulation]

A comparative study on effect of promoting ovulation between Bushen Tiaojing Decoction (BSTJD) and clomifene was conducted. Results showed that the ovulation rate of BSTJD group was 66.67%, as compared with that of clomifene group (61.54%), the difference was insignificant (P > 0.05), However, there was a significant difference (P < 0.05) between the two groups in effective rate of menoxenia treatment (82.14% versus 66.67%). No toxicity or side-effect appeared. These results suggested the BSTJD could definitely promote the ovulation, and has a good effect in treating menoxenia and improving the symptoms. The mechanism of BSTJD might be regulating the function of hypothalamus-pituitary-ovary system to promote ovulation.

Modification of AOAC multiresidue method for determination of synthetic pyrethroid residues in fruits, vegetables, and grains. Part II: Acetone extraction system

To optimize conditions and to evaluate further a multiresidue method for pyrethroids, various extraction solvents and partitioning conditions were examined. Acetone and acetonitrile (for fruits and vegetables) and acetone-water and acetonitrile-water (for grains) were used as solvents with or without acetonitrile partitioning. Twenty crops fortified with 8 pyrethroid insecticides at low, medium, and high levels were analyzed. For limit of detection (LOD) levels, repeatability tests were completed with acetone-water as extraction solvent. Recoveries of 8 pyrethroid insecticides at LOD levels were 76.2-99.6%, with coefficients of variation (CVs) of 2.08-10.90% for narrow-bore capillary gas chromatography (GC) (n = 6) and 80.1-107.3% with CVs of 3.76-15.38% for wide-bore capillary GC (n = 6). Both acetone or acetone-water extraction with acetonitrile partitioning and acetonitrile or acetonitrile-water extraction with acetonitrile partitioning are suitable for multiresidue analysis of pyrethroid insecticides. However, acetonitrile and acetonitrile-water as extraction solvents were better than acetone and acetone-water at LOD-fortified levels. This finding was confirmed chromatographically with pear, cucumber, and barley control samples.

Gene for cytochrome c oxidase subunit II in the mitochondrial DNA of Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae)

The cytochrome c oxidase subunit II (COII) gene between transfer RNA for Leu and Lys in the mitochondrial DNA of Culex quinquefasciatus Say and Aedes aegypti (L.) was amplified by the polymerase chain reaction (PCR) technique. Both the gene order and direction of transcription were identical to Anopheles and Drosophila. Nucleotide sequences of the PCR-amplified COII genes in these two mosquitoes exhibited 88% homology, and the frequency of transition was very close to that of transversion. The homology of deduced amino acid sequences of COII between these two mosquitoes was 95%. Two highly conserved segments of COII proteins were found in mosquitoes, fruit flies, locust, and honeybee. These segments contain the major amino acid residues of cytochrome c oxidase involved in electron transport and ligand binding. The amino acid residues are located at the positions similar to those of the mammalian enzymes. Two sets of the phylogenetic trees of a similar pattern were generated by comparing the divergences of nucleotide and amino acid sequences of COII. The branch lengths of the trees estimated by amino acid and nucleotide sequences showed different evolution rates of Aedes and Culex from their common ancestor.

Effect of enteral versus parenteral feeding on leucine kinetics and fuel utilization in premature newborns

To determine whether the route of nutrient delivery affects whole-body protein kinetics and fuel utilization, eight premature newborns were studied during both a 4-h period of enteral intake and a 4-h period of parenteral nutrition. The kinetics of the essential amino acid leucine were measured using a constant tracer infusion of 1-13C-leucine, and fuel utilization and energy expenditure were assessed by respiratory calorimetry. All leucine kinetic parameters were similar during enteral or parenteral nutrition (in mean +/- SD mumol/kg/h, flux = 233 +/- 51 enteral versus 258 +/- 42 parenteral, leucine from protein breakdown = 177 +/- 50 enteral versus 200 +/- 41 parenteral, leucine oxidation = 57 +/- 26 enteral versus 63 +/- 20 parenteral, and leucine used for protein synthesis = 176 +/- 63 enteral versus 196 +/- 50 parenteral). In addition, overall rates of energy expenditure (approximately 52 kcal/kg/d) and pattern of fuel utilization (approximately 70% carbohydrate, 13% fat, 17% protein) were unaltered by the route of feeding. Thus, as reflected by leucine kinetics, overall rates of protein turnover, synthesis, oxidation, and breakdown as well as energy expenditure and fuel utilization are similar when nutrition is provided to premature newborns by either the enteral or parenteral route. These results suggest that short-term provision of parenteral nutrition may be able to substitute appropriately for enteral intake, at least with regard to the utilization of one essential amino acid and the overall pattern of fuel utilization.

All-optical switching in an asymmetric silicon Fabry-Perot étalon based on the free-carrier plasma effect

We demonstrate all-optical switching at 1.3 and 1.5 µm in the reflection mode of an asymmetric silicon Fabry-Perot étalon by a control beam at 0.85 µm. Both switch-on and switch-off operations are demonstrated at different locations of the etalon. Based on the free-carrier plasma effect, a modulation depth as large as 10% is obtained and a frequency response as high as 0.5 GHz is achieved.

[Effects of alpha-adrenoreceptor excitation on the delayed after-depolarization of sheep cardiac Purkinje fibers]

By using acetyl strophanthidin (AS) 0.2 mumol/L, the delayed after-depolarization (DAD) was induced in sheep cardiac Purkinje fibers and recorded with intra-cellular microelectrode. When beta-adrenoceptor was blocked by propranolol 1.0 mumol/L, phenylephrine 1.0 mumol/L increased the amplitude of DAD from 8.1 +/- 2.2 mV to 9.5 +/- 2.8 mV, prolonged the duration of DAD from 240 +/- 47 ms to 273 +/- 47 ms (n = 13, P < 0.01) and increased the up rising velocity of DAD from 0.039 +/- 0.023 V/s to 0.051 +/- 0.026 V/s (n = 13, P < 0.05). The DAD occurred earlier for 30 +/- 47 ms to preceding action potential (n = 13, P < 0.05). When triggered action potentials were induced by norepinephrine 1.0 mumol/L on the basis of DAD, propranolol 1.0 mumol/L could suppress the triggered beats while phentolamine 1.8 mumol/L showed little effect. The above results indicate that excitation of alpha-receptor had only slight augmentation effect on DAD. However, for the triggered activity induced by DAD, the inhibitory effect of beta-blockers are stronger than that of alpha-blockers.