Diaphragmatic hypoplasia in association with hypoplastic lungs.
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Abnormalities, Multiple↗
Biomedical subjects
V Chan
Publications and source records attributed to V Chan.
Neonatal complications of extreme prematurity in mechanically ventilated infants.
Previous data have suggested that neonatal complications amongst preterm ventilated infants increase with decreasing gestational age and thus are likely to be greatest among ventilated infants of less than 28 weeks gestational age. The aim of this study was to test that hypothesis, thus we report the neonatal complications of 175 extremely preterm mechanically ventilated infants (gestational age less than or equal to 28 weeks). Of the infants 152 were ventilated because of respiratory distress syndrome (RDS) or respiratory distress of severe prematurity, 41% of these infants died. Amongst infants with RDS or respiratory distress of extreme prematurity, mortality was significantly increased in infants of gestational age less than or equal to 24 weeks and birth weight less than or equal to 1000 g. In this group 20% developed a pneumothorax, and mortality was inversely related to gestational age. In infants with RDS, 43% developed a periventricular haemorrhage and 37% were still oxygen-dependent at 28 days of age; neither of these complications was significantly related to birth weight or gestational age. Of infants with RDS 38% developed a patent ductus arteriosus and 16% developed retinopathy of prematurity. These data suggest that even amongst very immature infants there has been an impressive reduction in the neonatal complications of mechanical ventilation.
Gestational Age↗
Evaluation of triggering systems for patient triggered ventilation for neonates ventilator-dependent beyond 10 days of age.
The performance of two triggering systems was compared during patient triggered ventilation (PTV) of infants ventilator-dependent beyond 10 days of age. Ten infants were studied who had a median gestational age of 26.5 weeks and a postnatal age of 15.5 days. PTV was administered via the SLE ventilator and the two triggering systems, an airway pressure monitor and the MR10 respiration monitor, were used in random order each for 30 min. The airway pressure trigger had a superior performance in that, although it did not differ significantly in delivered inflation volume or sensitivity to the MR10 respiration monitor, it had a shorter trigger delay (P < 0.01). Oxygenation improved in eight of the ten infants on the airway pressure trigger, but only in three on the MR10 respiration monitor. The reduction in PaCO2 was greater during PTV with the airway pressure trigger compared with the MR10 respiration monitor (P < 0.01). We conclude that the airway pressure trigger has a superior performance compared to the MR10 respiration monitor trigger in infants who are ventilator-dependent beyond 10 days of age.
Chronic Disease↗
Lung function and the Hering Breuer reflex in the neonatal period.
Lung function and the occurrence of the Hering Breuer reflex during the neonatal period has been investigated. To assess the effect of extrauterine and intrauterine maturation on the strength of the reflex both preterm and term infants were recruited. Ten preterm infants, born at a median gestational age of 29.5 weeks (range 27-34) were studied serially over the first four weeks of life and 10 term infants were studied at a median postnatal age of 1.5 days (1-4). All of the infants were recruited from the neonatal unit and initially had had some form of respiratory distress. Respiratory rate, tidal volume and compliance were measured and end inspiratory occlusion performed in an attempt to provoke the Hering Breuer reflex. The Hering Breuer reflex was provoked in all infants on all occasions. There was no difference in the strength of the reflex between the preterm and term infants or preterm infants studied at different postnatal ages. All infants studied regardless of maturity or postnatal age had non-compliant lungs and a rapid respiratory rate. These data suggest a lack of intrauterine and extrauterine maturation of the Hering Breuer reflex in the neonatal period amongst infants with non-compliant lungs.
Aging↗
Positive end expiratory pressure in acute and chronic respiratory distress.
The optimum level of positive end expiratory pressure (PEEP) was determined in 16 infants with respiratory distress syndrome (median gestational age 29 weeks, median postnatal age 1 day) and in 16 infants with chronic respiratory distress (median gestational age 25 weeks, median postnatal age 15 days). All infants were studied at a PEEP sequence of 3, 0, 3, 6, and 3 cm H2O, all other ventilator parameters being kept constant. Each PEEP level was maintained for 20 minutes and at the end of each period arterial blood gas was checked. During acute respiratory distress syndrome there were no significant changes in oxygenation but arterial carbon dioxide tension (PaCO2) significantly decreased from a mean of 4.93 kPa at 3 cm H2O to 4.40 kPa at 0 cm H2O and increased to a mean of 5.87 kPa at 6 cm H2O. In the infants with chronic respiratory distress, oxygenation fell from a mean of 8.66 kPa at 3 cm H2O to 6.40 kPa at 0 cm H2O and improved at 6 cm H2O to a mean of 10.50 kPa. There were no significant changes in PaCO2. We conclude that addition of PEEP, up to 6 cm H2O, may be useful even after the first week of life. High levels of PEEP, however, have previously been reported, in certain infants, to result in circulatory disturbance. It is therefore important to assess the use of 6 cm H2O PEEP in a controlled study of longer term clinical outcome.
Acute Disease↗
Long-term survival of a baby with homozygous alpha-thalassemia-1.
Triplets born to a Chinese woman consisted of 2 healthy boys and a girl with hemoglobin Bart's hydrops syndrome. The girl with hemoglobin Bart's hydrops syndrome, confirmed by gene analysis to be homozygous for alpha-thalassemia-1, survives for 27 months at the time of reporting. The dilemma in sustaining her life and the availability of other therapeutic options are briefly discussed. This is the third case report of homozygous alpha-thalassemia-1 with long-term survival.
Child, Preschool↗
Severe localised pulmonary interstitial emphysema--decompression by selective bronchial intubation.
We report three infants (26-28 weeks gestational age) in whom selective bronchial intubation was associated with successful decompression of severe localised pulmonary interstitial emphysema, uniquely in two cases this involved intubation of the left main bronchus. Pulmonary interstitial emphysema did not recur despite maintenance of selective intubation for only 48 hours or less in all three cases.
Bronchi↗
Comparison of different rates of artificial ventilation for preterm infants ventilated beyond the first week of life.
The effect on blood gases of different ventilator rates in preterm infants ventilated beyond the first week of life was assessed. Seventeen infants, median gestational age 25 weeks, were studied at median postnatal age of 11 days. The infants were ventilated through a set sequence of rates: 30, 60, 30, 100 and 30 breaths per min (bpm), each rate being maintained for 20 min. Peak and positive end expiratory pressure and I:E ratio (1:1) were unchanged at each rate and mean airway pressure was kept constant by altering flow as necessary. No significant change in oxygenation was demonstrated at either rates of 60 or 100 bpm compared to 30 bpm. PaCO2 levels were, however, significantly reduced at 60 bpm (P less than 0.001) compared to 30 bpm; but this improvement in PaCO2 was not seen at 100 bpm. These results suggest that increasing ventilator rate higher than 60 bpm in the majority of infants ventilated after the first week of life is not advantageous.
Bronchopulmonary Dysplasia↗
Airway pressure triggered ventilation for preterm neonates.
The usefulness of airway pressure triggered ventilation for the preterm newborn has been assessed using a new patient triggered valveless ventilator, the SLE 2000 infant ventilator (SLE 2000). This ventilator performs well at fast rates with no inadvertent positive end expiratory pressure (PEEP) even at rates of 150 breaths per minute (bpm). The ventilator is triggered by a change in airway pressure equal to or exceeding 0.5 cmH2O. If the infant fails to achieve the change in airway pressure which will trigger the ventilator the infant is ventilated at the back-up rate which is predetermined in conventional mode prior to commencing PTV. Infants were ventilated for one hour on a conventional neonatal ventilator, then for one hour on the SLE 2000 in conventional mode without changing the ventilator settings and finally for one hour on the SLE 2000 in patient triggered mode. Arterial blood gases were checked at the end of each hour. During patient triggered ventilation (PTV) the peak pressure, inspiratory time and inspired oxygen concentration were the same as those used during conventional mode. Simultaneous recordings were made of flow, volume, ventilator and oesophageal pressure change, from this recording the trigger delay during PTV was calculated. The trigger delay, being the time lag from the start of spontaneous inspiration, indicated by the negative deflection in the oesophageal pressure trace, and the onset of the ventilator breath. Thirteen infants were included in the study, median gestational age 32 weeks (range 25-35) and birthweight 1640 g (range 838-3038). All were being ventilated for respiratory distress syndrome (RDS) and were 4 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)
Evaluation Studies as Topic↗
Rearrangement of immunoglobulin, T-cell receptor, and bcl-2 genes in malignant lymphomas in Hong Kong.
The pattern of malignant lymphomas in the Hong Kong Chinese population is characterized by a low incidence of Hodgkin's disease and follicular lymphomas. The authors studied the immunoglobulin (Ig), T-cell receptor (TCR), and bcl-2 gene rearrangement in 62 cases of malignant lymphoma in this population by Southern blot hybridization. Two cases of Hodgkin's disease showed no rearrangement of the Ig and TCR genes. All 42 cases of B-cell lymphoma had Ig heavy chain (JH) rearrangement with or without additional rearrangement of the light chains (C kappa and C lambda). One case of diffuse B-cell lymphoma had additional T-cell receptor beta-chain (C beta) rearrangement. Sixteen of 18 cases of T-cell lymphoma had C beta rearrangement, and one case of T-lymphoblastic lymphoma had additional JH rearrangement. Two of eight (25%) cases of follicular lymphoma but only one of the 34 (2.9%) cases of diffuse B-cell lymphoma had bcl-2 rearrangement that was detected by pFL-1 probe. None of the 62 cases showed bcl-2 rearrangement using the pFL-2 probe. In conclusion, the Ig and TCR gene rearrangement pattern of the lymphomas found in Hong Kong correlates well with the T-cell and B-cell lineage, which is similar to reports in the white population. However, the incidence of bcl-2 gene rearrangement in follicular B-cell lymphoma is lower than that reported in the US but comparable with that in Japan.
Chromosomes, Human, Pair 18↗
Prenatal diagnosis of alpha and beta thalassemias and hemophilia A: experience in Hong Kong.
Methods and strategies are described for the prenatal diagnosis of three common congenital disorders--alpha and beta thalassemias and hemophilia A. It is important to study the frequency of restriction fragment length polymorphisms and types of molecular defects in specific ethnic groups, since they are known to differ significantly. The studies reported here were carried out in southern Chinese who form the majority of the Hong Kong population. The information obtained is also useful for prenatal diagnosis in southern Chinese migrant populations in Canada, USA, Australia, UK and southeast Asia.
Female↗
Content areas for cardiac teaching: patients' perceptions of the importance of teaching content after myocardial infarction.
This descriptive study was undertaken to investigate patients' perceptions of the seven content areas commonly included in cardiac teaching in terms of how important and how realistic they were for being learned following the experience of an acute myocardial infarction (MI). Lazarus's stress-coping theory was used as a framework for the study. A sample of 30 MI subjects were interviewed before discharge and during early convalescence. Before discharge, subjects rated six out of the seven content areas as "important" for learning. Although the information was considered important, it was not rated as equally realistic to learn. During early convalescence, mean scores under 'important to learn' were slightly lower, but all seven content areas were rated as significantly more realistic to be learned (P less than 0.05). Little variation in patients' perceptions of the importance of teaching content was noted over time. However, there was major variation between their perceptions of how important and how realistic it was to learn the material before discharge. Both dimensions, how important and how realistic, are therefore crucial to consider in cardiac teaching.
Adult↗
The unit clerk lends a helping hand.
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Centralized Hospital Services↗
Gene activation by induced DNA rearrangements.
A murine cell line (EN/NIH) containing the retroviral vector ZIPNeoSV(x)1 that was modified by deletion of the enhancer elements in the viral long terminal repeats has been used as an assay system to detect induced DNA rearrangements that result in activation of a transcriptionally silent reporter gene (neomycin phosphotransferase, neo) encoded by the viral genome. The spontaneous frequency of G418 resistance is less than 10(-7), whereas exposure to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) or the combination of UV irradiation plus TPA resulted in the emergence of drug resistant cell lines at a frequency of 5 per 10(6) and 67 per 10(6) cells, respectively. In several of the cell lines that were analyzed a low level of amplification of one of the two parental retroviral integrants was observed, whereas in others no alteration in the region of the viral genome was detected. To determine the effect of the SV40 large T antigen on induced DNA rearrangements, EN/NIH cells were transfected with a temperature sensitive (ts) mutant of SV40 T. Transfectants were maintained at the permissive temperature (33 degrees C) for varying periods of time (1-5 days) in order to vary SV40 T antigen exposure, after which they were shifted to 39.5 degrees C for selection in G418. The frequency of emergence of drug resistant cell clones increased with duration of exposure to large T antigen (9-52 per 10(6) cells over 1-5 days, respectively), and all cell lines analyzed demonstrated DNA rearrangements in the region of the neo gene. A novel 18-kilobase pair XbaI fragment was cloned from one cell line which revealed the presence of a 2.0-kilobase pair EcoRI segment containing an inverted duplication which hybridized to neo sequences. It is likely that the observed rearrangement was initiated by the specific binding of large T antigen to the SV40 origin of replication encoded within the viral genome. The investigations with phorbol esters, UV light, and the SV40 large T antigen demonstrate the utility of the EN NIH cell lines for the study of induced DNA rearrangements and support the future use of this system to investigate the mechanism by which varied stimuli or specific gene functions promote DNA rearrangements.
Animals↗
A new codon 71 (+T) mutant resulting in beta zero thalassemia.
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Base Sequence↗
Effect of heat on the cytotoxicity and interaction with DNA of a series of platinum complexes.
The effect of elevated temperature on the cytotoxicity and interaction with DNA of a series of platinum(II) complexes was examined. CDDP showed greater enhancement in cell killing with heat than the other platinum(II) complexes. There were approximately 2 decades enhancement in cell killing by 10 microM CDDP at 42 degrees C compared to 37 degrees C. The other potential cross-linking agents also showed increasing cytotoxicity with increasing temperature. K2PtCl4 (500 microM) killed about 15 times more cells at 43 degrees C than at 37 degrees C and KPt(NH3)Cl3 (500 microM) killed about 18 times more cells at 43 degrees C than at 37 degrees C. The cytotoxicity of the triammine and tetraammine complexes was less influenced by temperature. There was no significant difference in the cytotoxicity of [Pt(NH3)3Cl]Cl at any of the temperatures examined. The cytotoxicity of [Pt(NH3)4]Cl2 (500 microM) was increased about 7-fold at 43 degrees C compared to 37 degrees C, but the total cell killing by this complex at 43 degrees C was less than 1 log. Carboplatin (250 microM) was about 5 times more toxic at 42 degrees C and killed about 2.5 decades more cells at 43 degrees C than at 37 degrees C. Although there was little enhancement in the cytotoxicity of trans-Pt(NH3)2Cl2 at 42 degrees C compared to 37 degrees C trans-Pt(NH3)2Cl2 (500 microM) was about 7 times more cytotoxic than at 37 degrees C. The interaction of the various drug/temperature treatments with supercoiled pBR322 plasmid DNA was examined to assess the effect of heat on the reaction of these agents with DNA. At 42 degrees C, CDDP was able to gradually alter the gel electrophoretic mobility of the plasmid DNA to near that of the linear form. This change also occurred at 37 degrees C but at a much slower rate. Carboplatin effected similar changes in the superhelical pBR322 DNA, and the effect of temperature appeared to increase the rate of the reaction. Trans-Pt(NH3)2Cl2 also interacted with the supercoiled DNA, but at a slower rate than CDDP even under hyperthermic conditions. These results indicate that neutral platinum complexes capable of cross-linking DNA interact positively with temperature elevation to increase cytotoxicity, and, that of the platinum complexes that meet these criteria, the effect of hyperthermia is greatest with CDDP.
Animals↗
An algorithm for the treatment of pain in advanced cancer.
An algorithm is presented that has been developed over the past three years to provide pain relief in advanced cancer. The hospital records of 92 patients were reviewed to evaluate the validity of the algorithm. The algorithm is as follows: the 24 hour oral consumption of opioids was converted to sustained release morphine. If ineffective usually over 360 mg daily the total 24 hour oral dose was divided by 6 to convert to I.V. If this was ineffective, usually over 10 mg/hr of morphine, the intravenous dose was divided by 10 and infused epidurally. Local anesthetic was added for plexus involvement. After four days, the patient was weaned from local anesthetic solution. If sharp pain or pain to movement persisted, 6% phenol in 1 to 2 ml aliquots was injected every 8-12 hours to a total of 5-8 ml. While the conversion from intravenous to epidural morphine was 10:1 that from epidural to intravenous was only 1:3. Intravenous dose converts directly to the subcutaneous. The conversion from intravenous to oral is 1:3. There view showed that the dosages at which the conversions were made varied considerably. The reasons for the wide variation are presented. In summary the algorithm is a good practical guide for treatment of cancer pain.
Adult↗
Multiple XbaI polymorphisms for carrier detection and prenatal diagnosis of haemophilia A.
Three XbaI restriction fragment length polymorphisms (RFLPs) can be detected using the factor VIII-intron 22 probe (p482.6) in a XbaI-KpnI double digest of genomic DNA. The XbaI (A) site had been reported by Wion et al (1986) to be in intron 22, while the two additional sites. XbaI (B) and XbaI (C), are shown here to be X-linked and close to the XbaI (A) site. The frequencies of heterozygosity for these three sites are 0.49, 0.18 and 0.30 respectively. In 75 females the observed heterozygosity rate for the XbaI (A) site is 0.41 and this increased to 0.57 with the two additional sites. Care should be exercised when interpreting the XbaI RFLPs, since the 1.4 kb XbaI/KpnI fragment and the 4.8 kb XbaI fragment are associated with both positive XbaI (A) and XbaI (B) sites. By the combined use of the multiple XbaI polymorphisms with the BclI site in intron 18, the carrier detection rate would increase to 67%. Four prenatal diagnoses had been performed using the multiple XbaI polymorphisms.
Factor VIII↗