Utilization of iron sources and its possible roles in the pathogenesis of Vibrio parahaemolyticus

Vibrio parahaemolyticus is an important enteropathogen in Japan, Taiwan and other coastal regions. The influence of the regulation of iron on the pathogenesis of this pathogen has not been well characterized. The growth of pathogenic and non-pathogenic strains of V. parahaemolyticus on iron-limited agar plates was stimulated by ferritin, lactoferrin and transferrin at 30 microM, and also by hemin, hemoglobin and ferric ammonium citrate at 100 microM. Spontaneous iron-utilizing mutant strains (mutants) were derived from a clinical strain, ST550. Compared with the parent strain, lowered virulence was demonstrated for these mutants, as assayed by adult mouse and suckling mouse models. The in vivo growth and enterotoxigenicity of these mutants were also lower in the suckling mice. Adherence of the mutants to excised mouse intestine was lower as demonstrated by scanning electron microscopy. The iron-regulated outer membrane protein profile also changed in selected mutants. These results indicate that iron-regulated outer membrane proteins and other unknown factors associated with iron utilization may have profound influences, besides iron acquisition, on the pathogenesis of V. parahaemolyticus.

Anaesthetic managements for conjoined twins with complex cardiac anomalies

PURPOSE

To describe the perioperative assessment and anaesthetic management for surgical separation of three sets of conjoined twins with complex cardiac anomalies threatened with arterial desaturation and haemodynamic instability.

CLINICAL FEATURES

Three sets of conjoined twins, one omphaloischiopagus, one omphalopagus, and one thoraco-omphalopagus, were considered for separation during the perinatal or infantile period. Preoperative functional evaluation including continuous pulse oximetry, capnography, and cardiac electrophysiological studies were considered to be as important as anatomical evaluation of the cardiac anomalies and cross-circulation by angiography in assessing the feasibility of surgical separation. Ipsilateral infusion of prostaglandin E1 and phenylephrine were applied to the cyanotic and healthy twins respectively, to restore arterial oxygenation intraoperatively and to avoid profound hypoxaemia.

CONCLUSION

Surgical separation and anaesthesia should be well planned and rehearsed before clinical deterioration of the weaker twin. Aggressive pharmacological intervention and understanding of the cross-circulation pathophysiology is necessary to manage critical situations during surgical separation and in the postoperative period.

Conscious sedation by low dose propofol infusion during spinal anesthesia for cesarean section

BACKGROUND

A simple sedative technique without inducing oversedation or amnesia for birth experience would be necessary for patients undergoing Cesarean section receiving regional anesthesia. Clinical effects and dose requirement of intravenous propofol infusion were evaluated for this purpose.

METHODS

Forty-five parturients under adequate spinal anesthesia were randomly assigned to three groups and propofol was given after the clamping of the umbilical cord. The loading doses and initial infusion rates for group A, B, C were 0.3, 0.4, 0.5 mg/kg and 3, 4, 5 mg/kg/h, respectively.

RESULTS

Oversedation was not found and verbal contact was maintained in patients of group A and B. Two patients in group C were oversedated. Cardiovascular and respiratory function remained stable in all three groups. The incidences of complete amnesia for the experience of baby shown and intraoperative nausea/ vomiting were low. Most patients were satisfied with the sedation technique.

CONCLUSIONS

Intravenous infusion of propofol with a rate of 3-4 mg/kg/h after 0.3-0.4 mg/kg bolus injection is a sale, simple and satisfactory intraoperative postdelivery sedation technique in elective patients undergoing Cesarean section under spinal anesthesia.

Coamplification of the ZFX and ZFY genes for sex identification in preimplantation embryos

Knowledge of the sex of an embryo may be particularly useful for couples who have a high risk of producing offspring with inherited genetic disorders. We present a rapid and reliable nested polymerase chain reaction strategy to simultaneously amplify the ZFX and ZFY genes at the single cell level. Forty single blastomeres isolated from six triploid preembryos were subjected to coamplification of ZFX and ZFY genes. The results obtained from the preembryo were consistent with the assigned genotype. The amplification rate was 80% for ZFX and 84% for ZFY. Our strategy can be applied to preimplantation diagnosis of single gene disorders, and is especially useful for preimplantation diagnosis and prevention of X-linked diseases in in vitro fertilization programs.

Systemic fungal infection in very low-birth-weight infants

This retrospective study was designed to investigate the related factors and outcome of systemic fungal infection in very low-birth-weight (VLBW) infants. Medical records of infants admitted to the neonatal intensive care unit of National Cheng Kung University Hospital between January 1990 and June 1994 were reviewed. Of the 262 VLBW infants, 15 (5.7%) had fungemia (14 Candida 1 Cryptococcus) during the study period. Among the fungemic infants, 60% also had urinary tract infection; 18% had central nervous system infection. Their mean birth weight was 1079 +/- 78 g (504-1474 g), and the gestational age was 28.6 +/- 0.6 weeks (23-32 weeks). Thirteen of them (87%) had respiratory distress syndrome and patent ductus arteriosus, while 60% had chronic lung disease. The percentage of antibiotic usage, parenteral hyperalimentation, endotracheal intubation, placement of central venous line and steroid therapy were 100%, 100%, 73%, 67% and 36% respectively. The mean age at diagnosis of fungemia was 40.5 +/- 4.8 days (10-76 days). Common clinical manifestations were respiratory deterioration (93%), poor feeding (58%) and fever (53%). The frequency of side effects of amphotericin B in decreasing order were: hypokalemia (54%), hyponatremia (31%) and decreased urine amount (23%). The mortality rate was 40%. It was concluded that systemic fungal infection in VLBW infants might result in high mortality and the side effects were high in the treated infants.

Cell-free conversion of a ubiquitous nuclear protein into a killer-cell-specific form that binds to the NF-P enhancer element of the mouse perforin gene

Two nuclear factors, designated NF-PI and NF-P2, have been shown to bind to an enhancer 9-base motif (5'-ACAGGAAGT-3', NF-P motif) present within the 5'-flanking region of the mouse perforin gene. Our previous studies have shown that, although NF-P1 and NF-P2 differ in cell-type distribution and molecular mass, with NF-P2 being killer-cell-specific and smaller, the two factors appear to share common DNA-binding subunit(s). We have postulated that the biochemical event involved in the induction of NF-P2 could be the dissociation of a non-DNA-binding subunit from NF-P1, rendering the newly formed NF-P2 transcriptionally active. By using a cell-free system in the present study, we have demonstrated that a variety of chemical agents capable of denaturing or dissociating protein complexes, including guanidinium/HCl, detergents (SDS plus Nonidet P-40) and high-salt solutions, could convert NF-P1 into NF-P2. Unlike in intact cells, where induction of NF-P2 is restricted to killer lymphocytes, this conversion occurred in nuclear extracts derived from both cytotoxic lymphocytes and non-cytotoxic cells. Although the mechanism that restricts the induction of NF-P2 to killer- lymphocytes in vivo remains unresolved, these results support the hypothetical 'dissociation' model for the generation of NF-P2. The results also imply that the absence of perforin expression in non-cytotoxic cells may be due to the suppression of the induction of the killer-cell-specific trans-acting factor NF-P2.

Blood and central venous pressure responses after serial tourniquet deflation during bilateral total knee replacement

Thirty-five patients who underwent one-stage bilateral total knee replacement were included in this study to determine whether there was any difference in hemodynamic effects following the deflation of the first and second tourniquets. The values of hemodynamic variables were not significantly different immediately before either the first or the second tourniquet release as compared to preoperative values. The changes in heart rate after the release of the first and second tourniquets showed similar patterns. The systolic and diastolic blood pressure decreased significantly after deflation of the first and second tourniquets. However, the decrease was more marked after the second tourniquet deflation. The level of central venous pressure decreased significantly after the release of the first and second tourniquets but the patterns of change were not significantly different. The need for administration of ephedrine was also higher after the deflation of the second tourniquet than after the first. We conclude that the blood pressure changes after the second tourniquet deflation are more pronounced than those following the first tourniquet deflation. Anesthesiologists must be aware of this phenomenon and prevent marked hemodynamic changes that could be detrimental to high-risk patients.

Expression and characterization of functionally active recombinant perforin produced in insect cells

A key cytolytic mediator used by killer lymphocytes, perforin (also known as pore-forming protein or cytolysin), has been shown to be capable of undergoing polymerization to form pores in cell membranes and cause osmotic lysis of target cells. Although perforin has been purified from killer lymphocytes and the coding gene has been cloned and sequenced, information concerning the domain structure of the perforin molecule has remained scarce. To overcome the difficulty in obtaining sufficient amounts of perforin and to further assess the functional relevance of the N-terminal portion of the perforin molecule in its lytic activity, we have attempted in the present study to produce recombinant perforins. Three forms of recombinant mouse perforin, a full-length form and two N-terminal truncated forms, have been expressed in insect (Spodoptera frugiperda (Sf9)) cells using recombinant baculovirus. Biochemical and functional characterization showed the purified full-length recombinant perforin to be capable of lysing target cells, inducing Ca2+ influx into target cells, and forming structural pores in target membranes. Significant lytic activities were also detected for the two truncated recombinant perforins lacking, respectively, the N-terminal 21 amino acid residues and 121 amino acid residues. Time course study showed that the latter acted less efficiently than the former. These results suggest the N-terminal portion of the perforin molecule to be an important, but not the only, domain responsible for the lytic function of the perforin molecule.

Expression and characterization of functionally active recombinant perforin produced in insect cells

A key cytolytic mediator used by killer lymphocytes, perforin (also known as pore-forming protein or cytolysin), has been shown to be capable of undergoing polymerization to form pores in cell membranes and cause osmotic lysis of target cells. Although perforin has been purified from killer lymphocytes and the coding gene has been cloned and sequenced, information concerning the domain structure of the perforin molecule has remained scarce. To overcome the difficulty in obtaining sufficient amounts of perforin and to further assess the functional relevance of the N-terminal portion of the perforin molecule in its lytic activity, we have attempted in the present study to produce recombinant perforins. Three forms of recombinant mouse perforin, a full-length form and two N-terminal truncated forms, have been expressed in insect (Spodoptera frugiperda (Sf9)) cells using recombinant baculovirus. Biochemical and functional characterization showed the purified full-length recombinant perforin to be capable of lysing target cells, inducing Ca2+ influx into target cells, and forming structural pores in target membranes. Significant lytic activities were also detected for the two truncated recombinant perforins lacking, respectively, the N-terminal 21 amino acid residues and 121 amino acid residues. Time course study showed that the latter acted less efficiently than the former. These results suggest the N-terminal portion of the perforin molecule to be an important, but not the only, domain responsible for the lytic function of the perforin molecule.

Rapid airway access by modified retrograde intubation

Rapid access to the airway is important to ensure successful resuscitation. However, the establishment of a patent airway by orotracheal intubation is not always easy. This is especially true in patients with upper airway pathology or anatomic variations. A modified retrograde intubation technique was developed using the plastic sheath of the spring guidewire of a central venous pressure (CVP) kit as an introducer. This is considered to be a simple and safe method to provide a secure airway where intubation is difficult or in an emergency. This report presents our clinical experience using this method in 10 patients.

Frequency of linear hyperechogenicity over the basal ganglia in young infants with congenital rubella syndrome

Five young infants with congenital rubella syndrome (CRS) underwent cranial ultrasonographic examinations and/or computed tomographic examinations. Only two of these infants were small for their gestational age, and none of them were microcephalic at birth. Deafness and ocular lesions were found in four patients, and congenital heart disease was found in three. All had abnormal ultrasonographic findings: linear-shaped hyperechogenicity over the basal ganglia was noted for five patients, periventricular punctate hyperechogenicity was noted for three, and subependymal cysts were observed in two. Follow-up ultrasonograms for two of the patients showed progressively enlarging hyperechogenic lesions. Calcification was found in both patients examined by means of computed tomography. All patients became microcephalic, with profound global developmental delay. Intracranial calcifications are common findings in patients with CRS. Ultrasonography should be performed for high-risk neonates, regardless of their symptoms. The finding of linear hyperechogenicity over the basal ganglia should prompt a search for all congenital infections, including CRS.

The role of labetalol and propofol in the management of HELLP syndrome--a case report

The acronym HELLP describes a syndrome of (H) hemolysis, (EL) elevated liver enzymes, and (LP) low platelets, which symptomatically defines a unique group of preeclamptic/eclamptic women. Pregnancies complicated by this syndrome are associated with poor maternal and fetal outcome. This poses a considerable challenge to the anesthesiologists as many of these patients require emergent Cesarean section. We reported a 30-year-old woman with gestation of 32 wk who sustained Cesarean section under the impression of pregnancy with HELLP syndrome. General anesthesia was performed for this patient. The preoperative evaluation, general management, and intraoperative monitoring system were described. The individual role and use of labetalol and propofol were also discussed in this report.

Silicone cream occlusive dressing--a novel noninvasive regimen in the treatment of keloid

BACKGROUND

The use of silicone oil in the treatment of hypertrophic scars has recently been much discussed. Silicone gel and silicone cream containing 20% silicone oil have been demonstrated to effectively treat hypertrophic scars. However, the results in treating keloid are variable.

OBJECTIVE

The purpose of this study was to evaluate the clinical efficacy of silicone cream with occlusive dressing in the treatment of keloid.

METHODS

An open study was performed in 15 Chinese patients with single or multiple keloids. Nineteen keloids were randomly selected and treated with silicone cream occlusive dressing (SCOD). The effectiveness was assessed using a scoring system involving elevation, redness, hardness, itching and tenderness or pain of the lesions.

RESULTS

Fifteen out of 19 keloids (79%) showed significant improvement after using SCOD for 6 months. None of the keloids progressed.

CONCLUSIONS

We conclude that SCOD is easy to apply, noninvasive, painless, almost free of side effects. It is especially useful in children and those who cannot tolerate the pain or inconvenience of other treatment procedures. The action mechanism of SCOD is still unclear, though hydration and occlusion rather than silicone itself may play an important role.

Seroepidemiology of measles in southern Taiwan: two years after implementation of the measles elimination program

The seroprevalence of the measles antibody in southern Taiwan 2 years after the launch of the two-dose measles elimination program was studied using serological surveillance. Sera from 868 healthy inhabitants were collected from January to December 1993. Measles IgG antibody was detected by enzyme-linked immunosorbent assay. Measles antibody was found in 82% of infants under 3 months of age, 26% of those between 4 and 9 months and 54% of those between 10 and 15 months of age. The most common reason for postponement of vaccination was due to concomitant illness during the scheduled vaccination period. The presence of measles antibody rose sharply in children over 15 months of age, reached 90% among preschool-aged children and was 93% in school-aged children. These data suggest that a high immunization coverage rate was achieved in children over 15 months of age (92%) and that a third measles immunization at age 12 is not necessary. Future strategies for measles control should aim at increasing the immunization coverage for children between 9 and 15 months of age.

Long-term propofol infusion and airway management in a patient with Goldenhar's syndrome

A 2-year-old patient of Goldenhar's syndrome received an operation for corneal transplantation. Difficult endotracheal intubation from the congenital anomaly was treated with laryngeal mask airway and pediatric fiberoptic laryngoscope. Long-term propofol infusion (> 10 h) for anaesthetic maintenance in this small child was used with rapid and smooth recovery.

Characterization of the manganese-resistant mutants derived from Vibrio parahaemolyticus

The virulence and some related factors of Vibrio parahaemolyticus are regulated by the level of iron. In this study, five Mn-resistant mutants were selected after N-methyl-N'-nitrosoguanidine treatment and two transfers in medium containing high levels of manganese chloride. Production of siderophores and the 77-kDa iron-regulated outer-membrane protein and the bacterial growth in these Mn-resistants were deregulated, as compared with the wild-type strain. In addition, the regulation of these phenomena was partially or completely restored by the introduction of Escherichia coli fur gene. Also, the total cellular protein profiles of the wild-type and mutants showed that production of some proteins were positively or negatively regulated by iron, and expression of some of these proteins remained unaffected in these mutants. These results suggested the presence of a complicated iron regulation system, similar to the Fur system of E. coli, in this pathogen.

Difference between in vivo and in vitro effects of propofol on defluorination and metabolic activities of hamster hepatic cytochrome P450-dependent mono-oxygenases

We have compared the in vivo and in vitro effects of propofol on cytochrome P450-dependent monooxygenase activities in hamster liver microsomes. Propofol (Diprivan) 10 mg/100 g body weight was injected i.p. twice a day for 2 weeks to induce cytochrome P450 enzymes. Liver microsomes were prepared by differential centrifugation. Metabolism of the cytochrome P450-dependent mono-oxygenase system was evaluated by measuring aniline hydroxylation, benzphetamine demethylation and benzo(a)pyrene hydroxylation. Defluorination of enflurane was assayed by detecting free fluoride metabolites. At similar concentrations as in the in vivo group, propofol in vitro exhibited concentration-dependent inhibition of metabolism of benzphetamine and benzo(a)pyrene. Aniline hydroxylation and defluorination of enflurane were inhibited to 78% of control with propofol 0.25 mmol litre-1. In propofol-treated hamsters, there was only minimal inhibitory or inductive effects on either mono-oxygenase activities or capacity for defluorination. This difference between the in vitro and in vivo effects of propofol on cytochrome P450 mono-oxygenase activities emphasizes the need for care when comparing in vitro and clinical data.

[Cytochrome P450-dependent monooxygenase system and anesthetics]

The cytochrome P450-dependent monooxygenases constitute the primary enzyme system responsible for the oxidative metabolism of a variety of xenobiotics and endogenous compounds including drugs, carcinogens, fatty acids and hormones. The monooxygenase system consists of multiple forms of P450 enzymes, NADPH-cytochrome reductase and phospholipids. The level sof P450s and associated monooxygenase activities are subject to be regulated by many environmental, physiological, and pathological factors. Inhalation and intravenous anesthetics are all metabolized through these biotransformation enzymes. The pharmacokinetic properties as well as the toxicity of the anesthetics are closely related to the inducing or inhibitory status of the monooxygenase isozymes. To understand the role of cytochrome P450-monooxygenases in drug metabolism is essential for us to handle the drug-to-drug interactions and adverse effects.

Characterization of the antiabsence effects of SCH 50911, a GABA-B receptor antagonist, in the lethargic mouse, gamma-hydroxybutyrate, and pentylenetetrazole models

Recent studies have shown that gamma-aminobutyric acidB (GABAB) receptor antagonists suppress absence seizures in animal models. (+)-5,5-Dimethyl-2-morpholineacetic acid, hydrochloride (SCH 50911) is a new GABAB antagonist that is structurally dissimilar to previously studied GABAB antagonists such as 3-aminopropyl-diethoxymethyl-phosphinic acid (CGP 35348), 3-aminopropyl-n-butyl-phosphinic acid (CGP 36742) or 3-aminopropyl-cyclohexylmethyl-phosphinic acid (CGP 46381). In this study we measured the antiabsence effects of SCH 50911 in three animal models: the lethargic (lh/lh) mutant mouse, which has spontaneous absence seizures; and two rat models in which absence seizures were induced by administration of either gamma-hydroxybutyrate or pentylenetetrazole. SCH 50911 abolished seizures in all three models in a dose-dependent fashion (ID100 = 8-170 mumol/kg). In each model SCH 50911 was more potent (ID50 = 2-22 mumol/kg) than the following antiabsence compounds: the GABAB antagonist CGP 35348 (ID50 = 210-890 mumol/kg); ethosuximide (ID50 < or = 142-1240 mumol/kg); trimethadione (ID50 = 520-1100 mumol/kg); and valproic acid (ID50 = 900-2360 mumol/kg). SCH 50911 was equipotent with the GABAB antagonist CGP 46381 (ID50 = 20 mumol/kg) in the lh/lh mouse model. These findings suggest that antiabsence activity may be a defining feature of GABAB receptor antagonists and provide a rationale for pursuing clinical trials of GABAB receptor antagonists in human patients with absence seizures.