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H Y Chang

Publications and source records attributed to H Y Chang.

At least 73 records · Page 4Linked to original sources
PubMed1998

Esophageal PP intervals for analysis of short-term heart rate variability in patients with atrioventricular block before and after insertion of a temporary ventricular inhibited pacemaker.

Heart rate variability (HRV) analysis is a useful method for assessment of the activities of autonomic nervous system. The RR intervals in ECG is measured for this purpose. However, RR intervals are not suitable for HRV analysis in atrioventricular block (AV) block patients with ventricular inhibited (VVI) pacemaker, as the intervals will be fixed by the ventricular pacemaker. Thus we used an esophageal lead to detect PP intervals for analysis of HRV. The aim of this study was to evaluate the short-term HRV by using an esophageal electrode to detect the atrial signal and PP intervals in AV block patients. Fifteen AV block patients before and after temporary VVI pacemaker and 15 subjects with normal AV conduction (control group) were enrolled in this study. The atrial signals from esophageal lead, ECG and intraatrial lead were recorded. The duration was 10 min. We compared correlation coefficient of PP intervals from different leads in AV block patients and the control group. We also compared the PP interval's variability parameters between the control group and AV block patients, before and after insertion of a temporary ventricular inhibited pacemaker. The esophageal PP intervals were excellently correlated with intraatrial AA intervals (r=0.98+/-0.01). The HRV using esophageal PP intervals with time domain demonstrated a significant decrease in patients with AV block (standard deviation of all PP intervals (SDNN) (s)=0.022+/-0.014; percentage difference between adjacent PP intervals that are greater than 50 ms (pNN-50) (%)=0.052+/-0.038; square root of the mean of squares of differences between duration of neighboring PP intervals (r-MSDD) (s)=0.322+/-0.082) but this returned to normal after insertion of a temporary ventricular inhibited pacemaker (SDNN (s)=0.035+/-0.009; pNN-50 (%)=2.540+/-1.682; r-MSDD (s)=0.542+/-0.190). However, the ratio of low frequency/high frequency (LF/HF) still increased (LF/HF=4.120+/-1.802). The result of this short-term HRV analysis suggested that withdrawal of vagal tone or increased sympathetic activity in AV block patients compared with the control group. This appearance was normalized after insertion of a temporary VVI pacemaker. however, abnormal sympathovagal balance still remained.

Aged↗
PubMed1998

Autoproteolytic activation of pro-caspases by oligomerization.

Initiation of apopotosis requires the conversion of procaspases to mature caspases. Here we show that oligomerization of pro-caspases is sufficient to induce proteolytic generation of mature caspase subunits and activation of their cell death activity. Deletion of the protein interaction motif DED from pro-caspase-8 greatly suppresses its apoptotic activity. Cell death activity can be restored by oligomerization of pro-caspase-8 protease domains by two heterologous inducible oligomerization systems. Induced oligomerization also activates the apoptotic activity of pro-caspase-1 but not pro-caspase-3. In vitro, oligomerization leads to pro-caspase processing to from the mature caspase subunits; this processing requires the intrinsic caspase activity of zymogens and proceeds via a novel order of cleavage events.

Apoptosis↗
PubMed1998

Outbreak of Candida albicans fungaemia in a neonatal intensive care unit.

During a 4-month period, 9 premature infants hospitalized in a neonatal intensive care unit (NICU) developed Candida albicans fungaemia. All 9 infants received antifungal agents. Fluconazole was administered in 7 patients and successfully eradicated this organism in 6 with no adverse effects. For epidemiological investigation, 64 environmental specimens and hand-washings of all 54 staff members involved in the NICU were examined for the presence of this organism. No C. albicans could be identified from environmental sources, while the hand-washing of 1 nurse was C. albicans-positive. Two genotyping methods, including electrophoretic karyotyping using contour-clamped homogeneous electric field gel electrophoresis and polymerase chain reaction-based direct sequencing of rRNA gene, were used in the analysis of the isolates recovered from blood cultures of the infants, the hand-washing of the nurse and 7 control isolates. Both methods yielded comparable results and revealed that all 13 isolates from infected infants as well as the isolate from hand washing of the nurse were of the same genotype while the control isolates were distinct. These results suggest that the outbreak of C. albicans fungaemia was caused by a particular strain and possibly via cross-infection. In addition, we showed that fluconazole seemed to be safe and effective in treating C. albicans fungaemia in neonates, although the data were limited.

Antifungal Agents↗
PubMed1998

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.

DNA, Plant↗
PubMed1998

Vagotomy attenuates but does not prevent the somnogenic and febrile effects of lipopolysaccharide in rats.

The role of the vagus nerve in the somnogenic and pyrogenic effects of lipopolysaccharide (LPS) was studied in rats. Control rats (n = 8) and rats subjected to bilateral subdiaphragmal vagotomy (VX; n = 9) were injected with 100 micrograms/kg i.p. LPS at the beginning of the dark period. Sleep and brain temperature (Tbr) were recorded for 23 h after the injections. LPS caused increases in non-rapid eye movement sleep (NREMS) for 12 h after the injection in control rats. Sleep intensity, as indicated by the slow-wave activity (SWA) of the electroencephalogram during NREMS, was suppressed. LPS elicited biphasic Tbr responses: an initial hypothermia was followed by increases in Tbr that lasted for approximately 20 h. In vagotomized rats, the NREMS responses to LPS were blunted. The magnitude of the LPS-induced NREMS increases was about one-half of that seen in control rats, and these sleep responses lasted only for 6 h. LPS did not affect SWA in VX animals. VX completely abolished the hypothermic responses to LPS and shortened the duration of the hyperthermia. The results suggest that the subdiaphragmal vagi play an important, but not exclusive, role in the somnogenic and pyrogenic actions of intraperitoneally injected LPS.

Animals↗
PubMed1998

Dose-response relationship and irreversible obstructive ventilatory defect in patients with consumption of Sauropus androgynus.

STUDY OBJECTIVES: To determine the dose-response aspect of pulmonary function impairment in patients with consumption of Sauropus androgynus for weight reduction. METHODS: A questionnaire and pulmonary function tests were performed in 194 patients with a history of consumption of S androgynus with or without chest symptoms. Patients with obstructive ventilatory defect received follow-up spirometry 22 to 24 months after beginning consumption of the vegetable. RESULTS: Data from 178 patients were analyzed. Patients generally consumed 150 g of S androgynus daily as raw juice (60.7%), sauteed (16.9%), mixed preparation (20.8%), or boiled (1.7%) for various periods of time. We divided patients into five groups according to the total dose consumed (group A, 0 to 1,799 g; group B, 1,800 to 3,599 g; group C, 3,600 to 5,399 g; group D, 5,400 to 7,199 g; and group E, > or =7,200 g). The frequency of obstructive ventilatory defect was higher in the high-dose group than in the low-dose group (A, 4/43=9.3%; B, 13/64=20.3%; C, 14/32=43.8%; D, 5/12=41.7%; and E, 13/27=48.1%; p < 0.01). In total, 49 patients (27.5%) had moderate to severe obstructive ventilatory defects without bronchodilator response. The FEV1 and FEV1 percent predicted in these 49 patients were 0.96+/-0.38 L (mean+/-SD) and 41.8+/-16.9%, respectively. Sixty-five percent of these 49 patients began to suffer from dyspnea in the third, fourth, or fifth month after taking the vegetable and no patient began to develop dyspnea later than 7 months after beginning consumption of the vegetable. Using stepwise multiple regression, we found that the FEV1 percent predicted was negatively associated with the total dose ingested (r=0.24, p < 0.01). Follow-up spirometry showed that the obstructive ventilatory defect was irreversible in all patients. CONCLUSIONS: Consumption of S androgynus can result in moderate to severe obstructive ventilatory defect within 7 months, and the disorder was irreversible in the observation period for 22 months.

Adolescent↗
PubMed1998

Respiratory mechanics before and after hemodialysis in mechanically ventilated patients.

Hemodialysis, which leads to negative fluid balance, is often required in mechanically ventilated patients with renal failure. We conducted a prospective study on the influence of hemodialysis on the respiratory mechanics in 14 mechanically ventilated patients (10 men, 4 women, mean age 70.1 +/- 8.1 yr) with various causes of renal failure requiring hemodialysis in an intensive care unit. Respiratory mechanics were measured before and after hemodialysis using the interrupter technique under constant flow and constant volume. The values of several parameters of respiratory mechanics were significantly lower after hemodialysis: peak airway pressure (26.97 +/- 4.62 vs 23.45 +/- 4.13 cmH2O), airway pressure at zero flow (23.81 +/- 4.18 vs 21.50 +/- 3.79 cmH2O), airway plateau pressure (18.56 +/- 3.70 vs 16.48 +/- 3.07 cmH2O), and intrinsic positive end-expiratory pressure (4.03 +/- 2.90 vs 2.65 +/- 1.84 cmH2O). Minimal respiratory resistance and maximal respiratory resistance were significantly decreased after hemodialysis (4.38 +/- 1.26 vs 2.99 +/- 1.00 cmH2O/L/s and 9.93 +/- 2.50 vs 8.39 +/- 2.43 cmH2O/L/s, respectively), but effective additional respiratory resistance and static respiratory compliance were not. Significant correlations were found between body weight reduction by hemodialysis and changes in minimal respiratory resistance (r = 0.758, p < 0.01), maximal respiratory resistance (r = 0.544, p < 0.05), and static respiratory compliance (r = 0.703, p < 0.01). We conclude that hemodialysis significantly alters the respiratory mechanics in mechanically ventilated renal failure patients and that the alteration may be related to the negative fluid balance caused by hemodialysis.

Aged↗
PubMed1998

cDNA cloning and expression analysis of the human UDPglucose dehydrogenase.

A cDNA clone encoding the human UDPglucose dehydrogenase was isolated from a liver cDNA library. The cDNA is 2,355 bp in length with an open reading frame which is capable of encoding a protein of 494 residues. The predicted primary sequence of the gene product is in good agreement with that of the bovine enzyme determined previously found by means of protein sequencing. Two major transcripts of the UDPglucose dehydrogenase gene with sizes of 2.8 and 2.35 kb, respectively, were observed by Northern analysis. The gene was found to be expressed in a variety of tissues with the highest level in liver, consistent with the physiological function of the enzyme in excretion of endo- and xenobiotics compounds.

Amino Acid Sequence↗
PubMed1997

Daxx, a novel Fas-binding protein that activates JNK and apoptosis.

The Fas cell surface receptor induces apoptosis upon receptor oligomerization. We have identified a novel signaling protein, termed Daxx, that binds specifically to the Fas death domain. Overexpression of Daxx enhances Fas-mediated apoptosis and activates the Jun N-terminal kinase (JNK) pathway. A C-terminal portion of Daxx interacts with the Fas death domain, while a different region activates both JNK and apoptosis. The Fas-binding domain of Daxx is a dominant-negative inhibitor of both Fas-induced apoptosis and JNK activation, while the FADD death domain partially inhibits death but not JNK activation. The Daxx apoptotic pathway is sensitive to both Bcl-2 and dominant-negative JNK pathway components and acts cooperatively with the FADD pathway. Thus, Daxx and FADD define two distinct apoptotic pathways downstream of Fas.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Neuronal nuclear acetyltransferases involved in the synthesis of platelet-activating factor are located in the nuclear envelope and show differential losses in activity.

Neuronal nuclear fraction N1 was isolated from cerebral cortices of 15-day-old rabbits, and nuclear subfractions prepared, in order to study the location of nuclear lyso platelet-activating factor (lyso-PAF) acetyltransferase and alkylglycerophosphate (AGP) acetyltransferase, and factors that affect the loss of these two nuclear activities. Subfractionation of prelabelled N1 indicated that the nuclear envelope had the highest percentage of the radioactive acetylated products alkylacetylglycerophosphate (AAGP) and PAF, and the distribution of these phospholipids reflected phospholipid distributions in the nuclear subfractions. The majority (95%) of radioactive AAGP and PAF was also recovered in Triton X-100 extracts of prelabelled nuclei, suggesting that these acetylated lipids are located in nuclear membranes rather than in the nuclear matrix/chromatin. Of the nuclear subfractions, the envelope had the highest AGP and lyso-PAF acetyltransferase specific activities which were close to corresponding values seen in the parent N1 fraction. Thus the nuclear AGP and lyso-PAF acetyltransferases were principally localized to the nuclear membranes. Differentials in activity loss were seen for the two acetyltransferase activities. In the nuclear envelope fractions, the lyso-PAF acetyltransferase was the more susceptible to oxidation reactions which could be reversed or blocked by the use of reducing agents. In preincubations, N1 showed greater losses in lyso-PAF acetyltransferase activity than in AGP acetyltransferase activity, losses which were not attributable to oxidation. Addition of cytosolic fraction S3 to preincubations promoted losses for each acetyltransferase in N1, and gave evidence for cytosolic and endogenous nuclear contributions to the activity loss. Addition of okadaic acid to the preincubations did not prevent the decline of either acetyltransferase in intact nuclei, but did diminish the loss of nuclear lyso-PAF acetyltransferase activity promoted by S3 addition, and also blocked the loss of this acetyltransferase seen in preincubations of isolated nuclear envelopes. This suggests that nuclear lyso-PAF acetyltransferase is susceptible to okadaic acid-sensitive nuclear and cytosolic protein phosphatase activities, while AGP acetyltransferase may lose activity by the action of other phosphatases or by other mechanisms within the nucleus.

1-Propanol↗
PubMed1997

Factors associated with early maternal postpartum discharge from the hospital.

OBJECTIVE: To examine if mothers discharged from the hospital after 1 night's stay or less (early discharge) differ from those discharged from the hospital after 2 or 3 nights' stay (regular discharge) in demographic, economic, behavioral, health status, and health services risk factors associated with maternal and infant well-being. DESIGN: Bivariate and logistic comparisons of women discharged from the hospital early or after a regular hospitalization as reported in the 1988 National Maternal and Infant Health Survey. PARTICIPANTS: Postpartum women. MAIN OUTCOME MEASURE: Postpartum discharge from the hospital after 1 night's stay or less in the hospital. RESULTS: Early discharge from the hospital occurred for 12.3% of 3,865 366 women. Logistic regression revealed 8 factors that were associated with early discharge from the hospital: less than a high school education, aged older than 35 years, inadequate prenatal care, lack of private insurance or receipt of Medicaid for delivery, giving birth in the western United States, plans to breast-feed, and care by midwives. Two factors were associated with an increased likelihood of a regular discharge from the hospital: report of a hospitalization during pregnancy and giving birth in the Midwest or Northeast. CONCLUSIONS: Significant numbers of mothers discharged from the hospital early manifested health and social risk factors associated with poor health outcomes. Economic factors seemed an important motivation for early discharge from the hospital, as did inadequate use of health services. Since brief hospitalization is prevalent, clinicians and administrators must assure that the objectives of medical contact during childbirth are met, if not through hospitalization, then through other mechanisms.

Delivery, Obstetric↗
PubMed1997

Selective activation of CCK-B receptors does not induce sleep and does not affect EEG slow-wave activity and brain temperature in rats.

Systemic injections of cholecystokinin octapeptide sulfate ester (CCK-8-SE) elicit various behavioral and autonomic responses, such as increases in nonrapid-eye-movement sleep (NREMS) and hypothermia. There are two CCK receptors; both CCK-A and CCK-B receptors are stimulated by CCK-8-SE. The relative importance of the CCK-A and CCK-B receptors in the somnogenic and hypothermic effects of CCK-8-SE is not well understood. In the present experiments, we studied the effects of the selective activation of CCK-B receptors by CCK tetrapeptide (CCK-4) or nonsulfated CCK-8 (CCK-8-NS) on sleep and brain temperature (Tbr). Rats were injected intraperitoneally with saline on the control day and with CCK-8-NS (10, 50, or 250 microg/kg) or CCK-4 (10, 50, or 250 microg/kg) on the test day 5-10 min before dark onset. Electroencephalogram, electromyogram, and Tbr were recorded for 12 h. None of the treatments affected sleep or Tbr significantly, with the exception of 10 microg/kg CCK-4, which transiently decreased the amount of NREMS, and 10 microg/kg CCK-8-NS, which slightly increased REMS. These results suggest that the activation of CCK-B receptors by systemic injection of CCK-4 or CCK-8-NS is not sufficient to elicit increased NREMS and hypothermia in rats.

Animals↗
PubMed1997

Comparative effects of L-NOARG and L-NAME on basal blood flow and ACh-induced vasodilatation in rat diaphragmatic microcirculation.

1. The effects of N omega-nitro-L-arginine (L-NOARG) and N omega-nitro-L-arginine methyl ester (L-NAME) on diaphragmatic microcirculation in male Sprague-Dawley rats were assessed under basal conditions and after acetylcholine (ACh) stimulation. In addition, L-arginine (L-arg) was used with the aim of preventing L-NOARG and L-NAME from inhibiting ACh-induced vasodilatation, in order to explore the possibility that L-NOARG is not only a nitric oxide (NO) synthase inhibitor but also a muscarinic receptor antagonist. 2. Male Sprague-Dawley rats were anaesthetized with urethane and mechanically ventilated. The left hemi-diaphragm of each rat was prepared and microvascular blood flow was recorded during continuous superfusion with bicarbonate-buffered prewarmed Ringer solution by using laser-Doppler flowmetry. The drugs were topically applied to the surface of the hemi-diaphragm. 3. Baseline microvascular blood flow was unaffected after 15 min superfusion with any one of the following agents: L-NOARG (0.1 mM). L-NAME (0.1 mM), L-arg (10 mM). 4. ACh (0.03 mM, 0.1 mM and 0.3 mM) elicited a significant increase of microvascular blood flow (171 +/- 16%, 214 +/- 55%, and 323 +/- 68% of baseline values, respectively), via interaction with the muscarinic receptor, for the vasodilator response was severely inhibited by 15 min superfusion with atropine (0.3 mM). 5. Following 15 min superfusion with either of the L-arg analogues (0.1 mM), the ACh-induced vasodilator response was significantly inhibited. Pretreatment with L-arg (10 mM) for 5 min, followed by co-administration of L-arg (10 mM) and L-NOARG (0.1 mM) for another 15 min significantly prevented the inhibitory effect of L-NOARG or ACh-induced vasodilatation. However, a similar pretreatment schedule with L-arg failed to prevent L-NAME from exerting its inhibitory effect. 6. Neither of the L-arg analogues potentiated sodium nitroprusside (10 microM and 30 microM)-induced vasodilatation. However, adenosine (0.1 mM)-induced vasodilatation was slightly but significantly attenuated by either L-NOARG (0.1 mM) or L-NAME (0.1 mM), an effect which was prevented by L-arg (10 mM). 7. In conclusion, an increase in endothelium-dependent blood flow stimulated by ACh may occur in diaphragmatic microcirculation of anaesthetized rats independently of low baseline NO activity. The results also suggest that L-NAME has muscarinic receptor antagonist action in addition to its ability to inhibit NO synthase. Thus, we suggest that L-NAME should not be used as a specific NO synthase inhibitor in the rat diaphragm in situations in which there is potential for muscarinic receptors to be stimulated.

Acetylcholine↗
PubMed1997

The involvement of ATP-sensitive potassium channels in beta 2-adrenoceptor agonist-induced vasodilatation on rat diaphragmatic microcirculation.

1. The effects of glibenclamide (GLB), a blocker of ATP-sensitive potassium (KATP) channels, on diaphragmatic microcirculation in male Sprague-Dawley rats were assessed under basal conditions and after beta 2-adrenoceptor-agonist stimulation. In addition, forskolin was used to bypass beta-adrenoceptors and GTP-binding proteins (G-protein) to explore the possible mechanism of GLB effects. For comparison, the relationships between KATP channel activity and cyclic GMP-mediated vasodilator responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were also assessed. 2. Male Sprague-Dawley rats were anaesthetized with urethane and mechanically ventilated. The left hemi-diaphragm of each rat was prepared and microvascular blood flow (QLDF) was recorded with laser-Doppler flowmetry during continuous superfusion with bicarbonate-buffered, prewarmed Ringer solution. The drugs were topically applied to the surface of the hemi-diaphragm. 3. Salbutamol (0.32-32 microM), terbutaline (0.32 microM-0.32 microM) and forskolin (0.32-10 microM) each elicited a concentration-dependent increase in QLDF. 4. Baseline microvascular blood flow was unaffected by a 30 min suffusion of 1 microM GLB (295 +/- 51 mV vs 325 +/- 62 mV. P = 0.738). 5. The vasodilator response elicited by salbutamol (0.32 microM, 1 microM and 3.2 microM and 10 microM), was significantly attenuated by a 30 min superfusion with 1 microM GLB; this salbutamol-induced vasodilatation was mediated via an interaction with beta-adrenoceptor receptors, as in other experiments it was greatly inhibited by 30-min superfusion with propranolol (10 microM). 6. Similarly, following 30-min superfusion with GLB (1 microM), the terbutaline (1 microM, 3.2 microM and 10 microM)-induced vasodilator response was almost abolished and the vasodilator responses induced by incremental concentrations of forskolin (0.32 microM, 1 microM and 3.2 microM) were also significantly attenuated. 7. Cromakalim (1.5 microM, 3 microM and 3.2 microM) produced an increase of QLDF in a dose-dependent manner, which was virtually abolished by GLB (1 microM). In contrast, the vasodilator responses induced by acetylcholine (32 microM, 0.1 mM, and 0.32 mM) or sodium nitroprusside (3.2 microM, 10 microM and 20 microM) were independent of GLB (1 microM). 8. In conclusion, KATP channels may be functional, but tonically inactive in the resting diaphragmatic microcirculation and the vasodilator effect of beta 2-adrenoceptor agonists may be partly mediated by KATP channels; the activation of KATP channels may involve the accumulation of cyclic AMP in vascular smooth muscle cells.

Adenosine Triphosphate↗
PubMed1997

Vasomotion in rat diaphragm microcirculation at rest and during stepwise arterial pressure reduction.

The effect of haemorrhagic hypotension on the incidence, frequency and relative amplitude of vasomotion in rat diaphragm microcirculation was assessed by laser Doppler flowmetry (LDF). Graded bleeding to four hypotension levels (80, 60, 40 and 30% of the control state) were performed in 24 Sprague-Dawley rats. The incidence of vasomotion was 83% in the control state, 96% at the 80% level, 100% at the 60% level, 96% at the 40% level, and 46% at the 30% level. The median fundamental frequency of vasomotion determined manually during the control state and at the hypotension levels (in descending order) was 4.11 (range, 3.29-5.58) cycles min-1 (cpm), 4.48 (3.21-5.92) cpm, 4.20 (3.5-5.56) cpm, 4.01 (3.33-5.36) cpm, 3.71 (3.25-4.49) cpm (P < 0.01 from the fundamental frequency at 80 and 60% hypotension levels). The median relative amplitudes determined manually during the control state and descending hypotension levels were 44.5% (range, 24.9-135.9%), 69.4% (26.6-147.2%), 84.0% (40.3-177.1%) (P < 0.01 from resting and last stage of bleeding), 90.40% (26.2-189.6%) (P < 0.01 from resting and last stage of bleeding), 69.2% (35.6-93.2%). We concluded first that during the resting condition, vasomotion was frequently present in diaphragm microcirculation, which is distinct from other vascular beds of skeletal muscles. Second, the relative amplitude of vasomotion during haemorrhagic hypotension plotted against decreasing blood pressure exhibited a reverse U-shaped curve with a maximum at 40-60% of the control blood pressure, while the frequency of vasomotion remained relatively constant until the last stage of haemorrhage and centred around 3-5 cpm.

Animals↗
PubMed1997

Identification and characterization of acoK, a regulatory gene of the Klebsiella pneumoniae acoABCD operon.

By using transposon insertional mutagenesis and deletion analyses, a recombinant clone containing the region upstream of the acoABCD operon of Klebsiella pneumoniae was found to be required for acetoin-inducible expression of the operon in Escherichia coli. The nucleotide sequence of the region was determined, and it displayed an open reading frame of 2,763 bp that is transcribed divergently to the acoABCD operon. This gene, designated acoK, is capable of encoding a protein with an overall 58.4% amino acid identity with MalT, the transcriptional activator of the E. coli maltose regulon. A conserved sequence for nucleotide binding at the N-terminal region, as well as a helix-turn-helix motif belonging to the LuxR family of transcriptional regulators at the C terminus, was also identified. Primer extension analysis identified two transcription initiation sites, S1 and S2, located 319 and 267 bp, respectively, upstream of the putative start codon of acoK. Several copies of NtrC recognition sequence [CAC-(N11 to N18)-GTG] were found in the promoter regions of both the acoK gene and the acoABCD operon. Acetoin-dependent expression of the acoABCD operon could be restored in the E. coli acoK mutants by supplying a plasmid carrying an intact acoK, suggesting a transactivating function of the gene product. The AcoK protein overproduced in E. coli was approximately 100 kDa, which is in good agreement with the molecular mass deduced from the nucleotide sequence. A specific DNA binding property and an ATPase activity of the purified AcoK were also demonstrated.

Acetoin↗
PubMed1997

Correlation of fine needle aspiration cytology and frozen section biopsies in the diagnosis of thyroid nodules.

AIMS: To evaluate the correlation of fine needle aspiration (FNA) cytology and frozen section biopsy in the diagnosis of thyroid nodules. METHODS: The medical records of 662 patients who underwent FNA cytology of the thyroid and thyroid surgery were analysed. Frozen section biopsies were taken from 586 of the 662 patients. The diagnostic correlations of FNA cytology, frozen section, and both FNA cytology and frozen section with definitive histological assessment were evaluated. RESULTS: Among the 662 patients who received FNA cytology, there were 356 cases (53.8%) diagnosed as benign, 114 cases (17.2%) as malignant, 148 cases (22.4%) as indeterminate, and 44 cases (6.6%) as unsatisfactory. The positive predictive value for the detection of malignancy by FNA cytology was 92.1% and the negative predictive value was 95.2%. The incidence of malignancy in the indeterminate cytological diagnosis was 23%. The diagnosis from frozen sections was benign in 445 cases (75.9%), malignant in 134 cases (22.9%), and deferred in 7 cases (1.2%). By frozen section, the positive and negative predictive values were 97% and 95.5%, respectively. Diagnostic accuracy up to 98% was achieved when FNA cytology and frozen section diagnoses were in agreement. No false positives were observed when FNA cytology and frozen sections were both positive for malignancy. When FNA cytology and frozen section diagnoses were discordant, frozen section showed a higher accuracy (78.9%) than FNA cytology (21.1%). In the face of an indeterminate or unsatisfactory cytological diagnosis, the diagnostic accuracy of frozen sections reached 92.6%. CONCLUSIONS: The results confirm that FNA cytology is a useful tool in the initial evaluation of thyroid nodules. Intraoperative frozen section is a valuable procedure to confirm the cytological diagnosis and identify malignancy in patients with indeterminate or unsatisfactory cytological diagnosis. With reliance on frozen sections as an intraoperative guide of thyroid surgery, the possibility of unnecessary extensive surgery and the need for the second operation are considerably lower.

Biopsy, Needle↗