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Biomedical subjects

K Fong

Publications and source records attributed to K Fong.

At least 19 recordsLinked to original sources
PubMed1992

Otoacoustic emissions, audiometric sensitivity loss, and speech understanding: a case study.

The clinical measurement of otoacoustic emissions can assist in differentiating between peripheral and central explanations for deficits in speech understanding. We present audiometric and distortion-product emission data in a case with sensorineural hearing loss and a deficit in speech understanding. The presence of evoked emissions argues against attributing the speech audiometric loss to cochlear defect.

Adult↗
PubMed1991

Cerebral-blood-flow-velocity measurements in neonates: technique and interobserver reliability.

The interobserver reliability for absolute cerebral-blood-flow-velocity measurements by colour and duplex Doppler sonography was tested in 32 neonates with a mean birth weight of 1489 (SD 644) g, and a gestational age of 29.9 (SD 3.5) weeks. Using standardized technique, two observers recorded on videotape, the Doppler spectrum of the anterior cerebral artery, the intracranial internal carotid artery and the middle cerebral artery. Peak systolic flow, end diastolic flow, mean flow velocity, resistive index and pulsatility index were computed from 3 consecutive waveforms by each observer. The estimates of interobserver reliability using the intraclass correlation coefficient of the examiners varied from 0.95 to 1.00. Therefore, cerebral blood flow velocity can be reliably measured in premature infants.

Blood Flow Velocity↗
PubMed1991

Prediction of lethal pulmonary hypoplasia and chorioamnionitis by assessment of fetal breathing.

Twenty-three pregnancies with fetuses at risk for pulmonary hypoplasia were studied weekly until delivery. The amount of time spent in fetal breathing activity was recorded under controlled conditions during 1 h using real-time ultrasound. An amniotic fluid index was determined. The clinicians and the pathologist were unaware of the ultrasound findings. Eight of 23 fetuses did not breathe at the last ultrasound examination. Three babies died of pulmonary hypoplasia and two of these showed fetal breathing before birth. The three deaths were associated with rupture of the membranes at less than or equal to 20 weeks gestation and of greater than or equal to 44 days duration. One infant developed bronchopulmonary dysplasia. The amniotic fluid index in these four pregnancies was low and the newborn infants had limb contractures. Chorioamnionitis/funisitis was noted in 13 placentas. Eight fetuses were assessed for fetal breathing within 2 days of birth. The lack of fetal breathing had sensitivity, specificity, positive and negative predictive values of 0.75 for chorioamnionitis/funisitis. In this pilot study the absence of fetal breathing was of no value in predicting lethal pulmonary hypoplasia, but was related to chorioamnionitis/funisitis. We recommend further studies of fetal breathing in relation to fetal/neonatal infections.

Chorioamnionitis↗
PubMed1991

The effect of aminophylline on the excursions of the diaphragm in preterm neonates. A randomized double-blind controlled study.

Aminophylline is used to treat apnoea and to facilitate weaning from assisted ventilation in preterm infants. Aminophylline is thought to increase respiratory drive centrally. We performed a randomized controlled double-blind study to determine if aminophylline increases the excursions of the diaphragm indicating a possible direct peripheral effect. Twenty-two neonates were randomized to treatment with intravenous aminophylline (n = 11) or to no treatment (n = 11). An ultrasonographer, who was blinded to the group assignment, studied the diaphragmatic excursions using a real time sector scanner. The posterior one-third of the right hemidiaphragm was localized and M-mode was used to record the diaphragmatic excursions on paper. The neonates were studied in an awake but quiet state. Aminophylline resulted in an increase (43%) in the excursions of the diaphragm (p = 0.012) with no change in respiratory rate or pCO2. These findings indicate that aminophylline had a measurable effect on the diaphragmatic motion. Further studies combining this technique with other techniques are needed to determine if the main effect of aminophylline in the prevention of apnoea is mainly central or peripheral.

Aminophylline↗
PubMed1989

Prenatal sonographic diagnosis of hepatic hemangioendothelioma with secondary nonimmune hydrops fetalis.

A case of fetal hepatic hemangioendothelioma with secondary nonimmune hydrops fetalis is presented. The prenatal diagnosis, made at 27 weeks' gestation by real-time ultrasonography and pulsed Doppler ultrasound, was confirmed by angiography and pulsed Doppler ultrasound, was confirmed by angiography and autopsy after the infant was born 2 weeks later. To the best of our knowledge, this is the first report of prenatal diagnosis of such an entity.

Adult↗
PubMed1988

Fetal thoracic circumference: a prospective cross-sectional study with real-time ultrasound.

We report a prospective cross-sectional study of ultrasound fetal chest growth during normal pregnancy. The fetal chest circumference was measured in 100 normal pregnancies from 13 to 41 weeks' gestation. Nomograms of chest circumference versus gestational age and femur length were constructed. Data from 18 cases at risk for pulmonary hypoplasia indicated that the fetal chest circumference measurement may be useful in the antenatal prediction of lethal or clinically severe pulmonary hypoplasia.

Anthropometry↗
PubMed1988

Serial measurements of cerebral blood flow velocity in preterm infants during the first 72 hours of life.

Serial measurements of cerebral blood flow velocity (CBFV) were made in 29 preterm infants, using continuous wave Doppler ultrasound. CBFV was measured in both anterior cerebral arteries and quantitative measurements of CBFV were determined using the area under the velocity curve. In all ventilated infants, CBFV increased significantly during the first 6 hours of life and continued to increase until 16 hours of age. Thereafter, CBFV remained relatively constant. This increase in CBFV was primarily the result of increased diastolic flow. Three infants who had evidence of intraventricular haemorrhage on cranial ultrasound, had similar CBFV compared with the infants with no evidence of haemorrhage. Two infants died and both demonstrated areas of periventricular leukomalacia at autopsy. These infants had a prolonged period of low CBFV. These measurements provide normal data for ventilated, preterm infants. As previously suggested in term infants, the initial rise in CBFV may be secondary to closure of the ductus although a generalized decrease in peripheral vascular resistance could also be a contributing factor. Fluctuations in CBFV rather than individual readings are probably more important in the genesis of IVH. An episode of significantly reduced CBFV is a poor prognostic sign.

Blood Flow Velocity↗
PubMed1988

Training in geriatric psychiatry: will the supply meet the demand?

The number of geriatric patients with major psychiatric disorders is expected to grow along with the rising proportion of people age 65 and older. Despite recognition of this growth and increases in the training of geropsychiatrists, the supply of specialists is unlikely to keep up with the demand. The authors argue for greater resource expenditure in fellowship programs and a focus on training academic leaders to serve as role models for general psychiatrists and other primary care givers.

Aged↗
PubMed1987

Practice of 3-dimensional treatment planning at the Fox Chase Cancer Center, University of Pennsylvania.

The use of 3-dimensional (3-D) dose distributions and dose-volume histograms in radiation therapy treatment planning is illustrated on a patient with a head and neck tumor. The patient was immobilized in a rectangular tissue compensation bolus box. The treatment was planned with a 14 MeV D-T derived fast neutron therapy beam. The isodose distributions and the dose-volume histograms at multiple adjacent levels are used to evaluate the adequacy of coverage of target volumes and the doses to the normal tissues. Such dose-volume histograms are useful and practical in summarizing the dose distribution throughout the irradiated volume, assessing the degree of uniformity of the dose distribution within the target volume, quantifying the amount of normal tissue irradiated, and evaluating rival treatment plans for both particle and nonparticle beams.

Fast Neutrons↗
PubMed1985

Isolation and characterization of a cDNA and a pseudogene for mouse lactate dehydrogenase-A isozyme.

A mouse lactate dehydrogenase-A cDNA was isolated and it was shown to contain the 393bp of the protein-coding sequence and 488bp of the 3' untranslated region. The amino acid sequence deduced from its open reading frame provided independent evidence for the sequence of residues 201-331 of mouse LDH-A subunit (muscle). This cDNA clone was used as a probe to isolate a mouse genomic clone containing a truncated, processed LDH-A pseudogene. This pseudogene showed 81.6% homology at 713 positions compared with the LDH-A cDNA sequence. The divergence of this pseudogene was estimated to have occurred 39 million years ago.

Animals↗
PubMed1985

Cloning and sequencing of cDNA encoding the complete mouse liver alcohol dehydrogenase.

The main ethanol-active alcohol dehydrogenase (ADH; alcohol:NAD+ oxidoreductase, EC 1.1.1.1) in mouse liver (ADH-AA) is similar in catalytic and molecular properties to horse liver ADH-EE and to the human class I ADHs. We have isolated cDNA clones encoding the entire mouse liver enzyme plus flanking regions. A mixture of 16 different oligonucleotides, each 14 bases long, was used to screen a liver cDNA library made from a DBA/2J mouse. A strongly hybridizing clone was found and identified as an ADH-encoding cDNA by partial DNA sequencing. This clone was used as a probe to identify others. Two overlapping cDNA clones together contained the entire protein-encoding region plus 100 nucleotides of the 5' noncoding region and 133 nucleotides of the 3' noncoding region culminating in a short poly(dA) tail. The amino acid sequence of the mouse liver enzyme deduced from this cDNA closely resembles that of horse liver ADH-E: 316 of 374 residues are identical, and 29 of the differences are conservative substitutions. The 5' region of this cDNA is interesting: the AUG that initiates the ADH polypeptide is preceded by an AUG that would encode the first amino acid of a tripeptide. Presumably termination of this tripeptide is followed by reinitiation at the AUG immediately preceding the sequence of the mature ADH polypeptide.

Alcohol Dehydrogenase↗
PubMed1979

Inhibition of deoxyribonucleic acid repair in Escherichia coli by caffeine and acriflavine after ultraviolet irradiation.

The effects of caffeine and acriflavine on cell survival, single-strand deoxyribonucleic acid break formation, and postreplication repair in Escherichia coli wild-type WP2 and WP2 uvrA strains after ultraviolet irradiation was studied. Caffeine (0.5 mg/ml) added before and immediately after ultraviolet irradiation inhibited single-strand deoxyribonucleic acid breakage in wild-type WP2 cells. Single-strand breaks, once formed, were no longer subject to repair inhibition by caffeine. At 0.5 to 2 mg/ml, caffeine did not affect postreplication repair in uvrA strains. These data are consistent with the survival data of both irradiated WP2 and uvrA strains in the presence and absence of caffeine. In unirradiated WP2 and uvrA strains, however, a high caffeine concentration (greater than 2 mg/ml) resulted in gradual reduction of colony-forming units. At a concentration insufficient to alter survival of unirradiated cells, acriflavine (2 microgram/ml) inhibited both single-strand deoxyribonucleic acid breakage and postreplication repair after ultraviolet irradiation. These data suggest that although the modes of action for both caffeine and acriflavine may be similar in the inhibition of single-strand deoxyribonucleic acid break formation, they differ in their mechanisms of action on postreplication repair.

Acridines↗