Biomedical subjects

Y H Lam

Publications and source records attributed to Y H Lam.

At least 19 recordsLinked to original sources

PubMed2002

The clinical efficacy of neoadjuvant chemotherapy in squamous esophageal cancer: a prospective nonrandomized study of pulse and continuous-infusion regimens with Cisplatin and 5-Fluorouracil.

BACKGROUND: We evaluated cisplatin and 5-fluorouracil as preoperative adjuvant chemotherapy for patients with locally advanced squamous esophageal cancer and compared two different infusion regimens. The outcomes were also compared with those of our historical control patients treated by surgery alone. METHODS: From 1991 to 1997, 83 consecutive esophageal cancer patients underwent surgical exploration after completion of two cycles of cisplatin and 5-fluorouracil chemotherapy regimens, either in pulse or in continuous infusion cycles. Outcomes were compared with those of 76 historical control patients. Both groups were comparable in demographic characteristics and tumor stages. The resection rates, operative morbidity, mortality, and survival rates were compared. RESULTS: Partial response was achieved in 50% of patients who received chemotherapy. There was no chemotherapy-related mortality. The resection, morbidity, and mortality rates and median survival between the surgery-alone group and the chemotherapy group were 71.1% vs. 82%, 51% vs. 55%, and 4% vs. 10.8%, 12.0 vs. 13.5 months, respectively (P >.05). There was also no statistically significant difference between the two regimens. CONCLUSIONS: Preoperative adjuvant chemotherapy with cisplatin and 5-fluorouracil infusion, in pulse or continuous regimens, followed by surgery for squamous esophageal cancer patients had no added benefit in the overall survival.

Adult↗

PubMed2002

Sonographic features of anal atresia at 12 weeks.

Anorectal atresia results from abnormal development of the anorectal septum. Prenatal diagnosis is difficult but the condition may be suspected by the sonographic demonstration of a dilated colon. We present the sonographic features of a fetus with anal atresia and a ventricular septal defect at 12 weeks of gestation. This case illustrates that a dilated colon may be present in association with fetal anal atresia as early as 12 weeks.

Abnormalities, Multiple↗

PubMed2001

Early clinical outcomes after subfascial endoscopic perforator surgery (SEPS) and saphenous vein surgery in chronic venous insufficiency.

BACKGROUND: Subfascial endoscopic perforator surgery (SEPS) has recently become popular as a minimally invasive way to treat chronic venous insufficiency (CVI) of the lower extremities. We report the early clinical outcomes of SEPS and saphenous vein surgery in a prospective series of Chinese patients who presented with severe CVI. METHODS: All patients referred to our hospital for the management of severe CVI (class IV disease or above) after January 1998 underwent SEPS using an ultrasonic scalpel in conjunction with saphenous vein surgery. All patients were followed up prospectively to assess ulcer healing, ulcer recurrence, and symptoms after SEPS. Clinical outcome was evaluated by the scoring system suggested by the Consensus Committee of the American Venous Forum on Chronic Venous Disease. RESULTS: Over a 24-month period, we performed 36 SEPS on 31 patients. Nineteen lower extremities (53%) had active or healing ulcers. Sapheno-femoral ligation was also performed in 33 limbs (92%). Four limbs (11%) developed superficial wound infection, and two (6%) had saphenous nerve dysesthesia. The mean clinical score and disability score decreased from 8.42 to 3.42 and 1.45 to 0.31 respectively, after a median follow-up of 14 months (range, 6-22) (p < 0.005). Eleven ulcers (58%) healed within 6 weeks after surgery. At 1-year follow-up, ulcer recurrence was found in two legs (11%). CONCLUSION: SEPS is safe and feasible. Early clinical results have shown a promising outcome in patients with severe chronic venous insufficiency.

Adult↗

PubMed2001

The effect of fetal gender on nuchal translucency at 10-14 weeks of gestation.

Recent data have suggested that fetal nuchal translucency (NT) is affected by fetal gender. We investigated the size of this effect in 12 189 unselected pregnancies with known normal outcomes that had undergone NT measurements between 10 and 14 weeks of gestation. NT increased with gestation and was converted to multiples of the median (MoM) for the gestational day. The median NT MoM (95% CI) for female fetuses was 0.98 (0.97-0.99). This was significantly lower than that of the male fetuses (1.03; range 1.02-1.04) (p<0.0005; Wilcoxon rank-sum test). The gender difference was not observed at 10 weeks but was observed from 11 weeks onwards. There is no obvious explanation for the above findings.

Adult↗

PubMed2001

Subfascial endoscopic perforator vein surgery (SEPS) using the ultrasonic scalpel.

Subfascial endoscopic perforator vein surgery (SEPS) was recently introduced as a minimally invasive method to ligate incompetent perforating veins in patients with severe chronic venous insufficiency of the lower extremities. Herein we describe a technique in which we used a 5-mm ultrasonic scalpel for the transection of perforating veins in 16 SEPS performed in 14 patients. The use of the ultrasonic scalpel allowed for the precise coagulation and transection of the perforator vein with hemostasis, while avoiding the use of metal clips. Our initial results showed that the technique was feasible with minimal morbidity. We recommend the use of the ultrasonic scalpel as an alternative tool to transect perforating veins in SEPS.

Adult↗

PubMed2001

Solid-state NMR structure determination of melittin in a lipid environment.

Solid-state (13)C NMR spectroscopy was used to investigate the three-dimensional structure of melittin as lyophilized powder and in ditetradecylphosphatidylcholine (DTPC) membranes. The distance between specifically labeled carbons in analogs [1-(13)C]Gly3-[2-(13)C]Ala4, [1-(13)C]Gly3-[2-(13)C]Leu6, [1-(13)C]Leu13-[2-(13)C]Ala15, [2-(13)C]Leu13-[1-(13)C]Ala15, and [1-(13)C]Leu13-[2-(13)C]Leu16 was measured by rotational resonance. As expected, the internuclear distances measured in [1-(13)C]Gly3-[2-(13)C]Ala4 and [1-(13)C]Gly3-[2-(13)C]Leu6 were consistent with alpha-helical structure in the N-terminus irrespective of environment. The internuclear distances measured in [1-(13)C]Leu13-[2-(13)C]Ala15, [2-(13)C]Leu13-[1-(13)C]Ala15, and [1-(13)C]Leu13-[2-(13)C]Leu16 revealed, via molecular modeling, some dependence upon environment for conformation in the region of the bend in helical structure induced by Pro14. A slightly larger interhelical angle between the N- and C-terminal helices was indicated for peptide in dry or hydrated gel state DTPC (139 degrees -145 degrees ) than in lyophilized powder (121 degrees -139 degrees ) or crystals (129 degrees ). The angle, however, is not as great as deduced for melittin in aligned bilayers of DTPC in the liquid-crystalline state (approximately 160 degrees ). The study illustrates the utility of rotational resonance in determining local structure within peptide-lipid complexes.

Carbon Isotopes↗

PubMed2001

Successful mismatched sibling cord blood transplant in Hb Bart's disease.

A 20-month-old girl with Hb Bart's disease, who had survived neonatal complications, underwent HLA-DR antigen mismatched sibling cord blood transplantation successfully. Immune thrombocytopenia, which occurred around 2.5 months after transplant, responded to intravenous gamma-globulin. The fetal hemoglobin level rose to a peak of 52.3% on day +69 post transplant and declined gradually during the following year. Ten percent of hemoglobin Bart's was detected 2 months after transplant and this reflects the alpha-thalassemia trait of the donor.

Female↗

PubMed2001

Quantitative polymerase chain reaction for the rapid prenatal diagnosis of homozygous alpha-thalassaemia (Hb Barts hydrops fetalis).

A quantitative polymerase chain reaction (Q-PCR) method based on the TaqMan technology has been devised for the prenatal diagnosis of homozygous alpha*-thalassaemia (south-east Asian type deletion). Primers and TaqMan probes were designed to specifically amplify an alpha*-thal chromosomal fragment or a normal alpha-chromosomal fragment. Variations in input target DNA in individual sample wells were normalized by the simultaneous amplification of a beta-actin gene fragment and results expressed as a ratio to that of beta-actin. There was no overlap of the data between the homozygous alpha*-thal, alpha*-thal and normal subjects. Up to 5% maternal DNA (alpha*-thal) contamination did not affect the specificity of the result. In 31 prenatal diagnoses, the result using Q-PCR compared favourably with the gold standard of Southern hybridization of alpha-genes.

Actins↗

PubMed2001

Ductus venosus Doppler study in fetuses with homozygous alpha-thalassemia-1 at 12 to 13 weeks of gestation.

OBJECTIVE: Fetuses affected by homozygous alpha-thalassemia-1 are anemic from the first trimester of pregnancy. We investigated ductus venosus Doppler velocimetry in these affected fetuses at 12-13 weeks of gestation. DESIGN: Prospective observational study. SUBJECTS: Women referred for the prenatal diagnosis of homozygous alpha-thalassemia-1 before 14 weeks of gestation. METHODS: All fetuses underwent pulsed Doppler investigations following color flow mapping at 12 or 13 weeks of gestation. Homozygous alpha-thalassemia-1 was diagnosed by DNA or hemoglobin study. The ductus venosus Doppler indices--Vmax (peak velocity during ventricular systole), Vmin (minimum forward velocity during atrial systole), TAMX (time-averaged maximum velocity), PIV (pulsatility index for veins, Vmax-Vmin/TAMX), PLI (preload index, Vmax-Vmin/Vmax) and Vmax/Vmin ratio--were compared between the affected fetuses and fetuses unaffected by homozygous alpha-thalassemia-1. RESULTS: Between June 1998 and October 1999, 102 eligible women were recruited. Fetal ductus venosus Doppler study was successful in 96 pregnancies (94%). Of these, 20 fetuses were affected by homozygous alpha-thalassemia-1. None of them showed hydropic changes at the time of Doppler study. The affected fetuses had significantly higher ducts venosus Vmax (30% increase), Vmin (50% increase) and TAMX (20% increase) and significantly lower Vmax/Vmin ratio, PIV and PLI values. CONCLUSION: Fetuses affected by homozygous alpha-thalassemia-1 at 12-13 weeks had increased forward flow velocities in the ductus venosus throughout the cardiac cycle. The increase of venous return is consistent with our previous report of cardiac dilatation and an increase of cardiac output in the affected fetuses at this stage as a compensatory mechanism for anemia and hypoxia. However, extensive overlap of the ductus venosus Doppler indices between affected and unaffected fetuses precludes its use in predicting anemia at 12-13 weeks.

Blood Flow Velocity↗

PubMed2001

The effect of fetal gender on second-trimester maternal serum inhibin-A concentration.

Second-trimester serum inhibin-A is increasingly used as a fourth marker in addition to the triple test to screen for Down syndrome. We investigated whether fetal gender had an effect on serum inhibin-A concentration. A retrospective analysis was done on 316 normal pregnancies and 48 Down syndrome pregnancies in which maternal serum inhibin-A assays were performed between 15 and 20 weeks of gestation and in which the fetal sex was known. The median inhibin-A MoM (95% CI) for normal pregnancies in the presence of a male fetus was 0.93 (range 0.88-1.03). This was significantly lower than that in the presence of a female fetus (median MoM=1.04). The gender difference was not observed in the Down syndrome pregnancies. The increased inhibin-A concentration would lead to a 2.3-fold higher false-positive rate in the presence of a female fetus (10.6% vs. 4.6%; p<0.05, Chi-square test). Because of the small number of cases studied, the results need to be substantiated by a larger series. If the gender effect is confirmed, adjustment for fetal sex may be necessary when inhibin-A is used as a screening marker.

Adult↗

PubMed2001

Isolated foetal ascites.

The prenatal diagnosis and perinatal outcome of two patients with isolated foetal ascites compatible with chyloperitoneum is described. The foetal ascites resolved spontaneously after delivery with good perinatal outcome in both cases. A good prognosis can be anticipated in such cases. Antepartum and intrapartum interventions are seldom necessary.

Adult↗

PubMed2000

Acceptability of serum screening as an alternative to cytogenetic diagnosis of down syndrome among women 35 years or older in Hong Kong.

The addition of second trimester serum markers to maternal age increases the efficacy of screening for Down syndrome by maternal age alone. Among women aged 35 years or older, serum screening makes a large proportion of amniocentesis unnecessary. However, there are ethical and medicolegal concerns about serum screening in 'old' women, largely because some of the pregnancies affected by Down syndrome and other chromosomal abnormalities may not be detected. We investigated the acceptability of serum screening in women aged 35 years or older when it was offered as an alternative to prenatal cytogenetic diagnosis after detailed counselling. Women referred for prenatal diagnosis of Down syndrome because of advanced maternal age were given the options of cytogenetic diagnosis by chorionic villus sampling (CVS) or amniocentesis. As an alternative, they could choose to undergo second trimester serum human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) screening first before deciding on whether to undergo amniocentesis. Between January 1997 and October 1999, 3419 subjects were recruited. 1807 women (52. 9%) chose to undergo serum screening, 1516 women (44.3%) chose to have amniocentesis and 96 women chose to have CVS (2.8%). The proportion of women who chose serum screening rose steadily from 38. 8% in the year of 1997 to 63.4% in 1999. Significantly fewer Chinese women chose serum screening than non-Chinese. The decision as to whether to undergo an invasive diagnostic procedure or to be content with the relatively safer but less accurate screening test varies, being affected by the women's background and culture.

Adult↗

PubMed2000

Prenatal diagnosis of haemoglobin Bart's disease by cordocentesis at 12-14 weeks--experience with the first 59 cases.

We have shown that fetuses affected by haemoglobin (Hb) Bart's disease can be reliably identified by their sonographic manifestation of cardiac enlargement at 12-14 weeks. Between 1995 and 1999, 282 couples were seen before 15 weeks. They were offered the options of chorionic villus sampling, or amniocentesis and DNA study, or ultrasound examination at 12-14 weeks, followed by cordocentesis and Hb study only when the ultrasound findings were abnormal. Two hundred and thirty-four at-risk pregnancies had ultrasound assessment at 12-14 weeks, 62 fetuses showed enlarged cardiothoracic ratio [mean (SD) 0.54 (0.02)] and four of them also had hydropic changes. Fifty-nine women agreed to undergo cordocentesis at 12-14 weeks and the procedure was successful in 57 cases (97%). Cordocentesis were performed by a freehand technique using a 26- or 24-gauge spinal needle with a 20-gauge introducer. Fifteen fetuses (25%) had bleeding from the cord and 12 fetuses (20%) had bradycardia following cordocentesis. The fetal loss rate was 8% (5/59). Hb Bart's disease was confirmed in all the 62 fetuses with cardiac enlargement. Their Hb concentration ranged between 3.1 to 8.4 g/dl. One hundred and seventy-two fetuses had normal ultrasound assessment and 148 of them were confirmed to be unaffected by Hb Bart's disease. Twenty-three pregnancies were ongoing and one miscarried at 15 weeks. We believe that sonographic assessment followed by selective cordocentesis at 12-14 weeks is a feasible prenatal diagnostic option for Hb Bart's disease.

Adult↗

PubMed2000

Conformational studies of a melittin-inhibitor complex.

The conformation of a melittin-inhibitor complex was studied by solution NMR, solid-state NMR, and circular dichroism. In solution, binding was studied by titrating inhibitor against melittin in dimethyl sulfoxide, methanol, aqueous buffer, and dodecylphosphocholine micelles. The change in chemical shift of Trp19 resonances and the formation of a precipitate at 1:1 molar ratio indicated that the inhibitor was bound to melittin. Solid-state NMR also showed a change in chemical shift of two labeled carbons of melittin near Pro14 and a change in 1HT1 relaxation times when complexed with inhibitor. Rotational resonance experiments of melittin labeled in the proline region indicated a change in conformation for melittin complexed with inhibitor. This observation was also supported by circular dichroism measurements, indicating a reduction in alpha-helical structure for increasing ratios of inhibitor bound to melittin.

Amino Acid Sequence↗

PubMed2000

Serial sonographic features of a fetus with hydranencephaly from 11 weeks to term.

Fetal hydranencephaly is a rare congenital cerebral abnormality characterized by complete or near complete absence of the cerebral cortex. We present the sonographic evolution of a case of fetal hydranencephaly from 11 weeks of gestation to term. At 11 weeks, the fetal head appeared small and the forehead was sloping. The normal cerebral hemispheres could not be identified. Follow-up sonography showed that the cerebral hemispheres were almost entirely replaced by fluid, except in the occipital region. The baby died 2 weeks after birth. Post-mortem examination confirmed the diagnosis of hydranencephaly.

Adult↗

PubMed2000

Sonographic diagnosis of congenital megalourethra at 13 weeks of gestation.

Congenital megalourethra is a rare disorder characterized by the congenital absence of the corpus spongiosum and/or corpus cavernosum, leading to dilatation of the urethra. We present a case of congenital megalourethra diagnosed by ultrasound examination at 13 weeks of gestation. Transabdominal and transvaginal sonography showed gross megacystis, bilateral hydronephrosis and a cystic dilatation of the penis. Transabdominal needle embryoscopy confirmed a balloon dilatation of the fetal penis. The pregnancy was terminated by suction curettage.

Adult↗

PubMed2000

Thermocoagulation for selective reduction of conjoined twins at 12 weeks of gestation.

Conjoined twins occur rarely. Most of the prenatally diagnosed cases are terminated either because of extensive organ sharing or because of the presence of major structural abnormalities. We present a case of omphalopagus conjoined twins diagnosed at 10 weeks of gestation with selective reduction performed at 12 weeks. The twins were conjoined at the umbilicus with vascular communication demonstrated at the conjunction. Twin A was normal but twin B was growth restricted and hydropic. Thermocoagulation of twin B was performed at 12 weeks by passing an insulated electric wire through a 18-gauge needle placed close to the fetal heart. Reassessment at 15 weeks showed that twin A was growing normally with a small dead twin B attached at its umbilicus. Twin B was subsequently sloughed off from this attachment and could be seen lying free in the amniotic cavity at 17 weeks. Twin A was delivered at term and was healthy. A small scar could be seen just above the umbilical cord insertion. This case represents the first antenatal example of selective reduction of conjoined twins by thermocoagulation.

Adult↗

PubMed2000

Limb reduction defects as the sonographic manifestation of hemoglobin Bart's disease at 10 weeks of gestation.

Fetuses affected by hemoglobin Bart's disease are anemic and hypoxic from the first trimester. They develop cardiac and placental enlargement and have a high incidence of limb reduction defects and hypospadias. We present a fetus at risk for hemoglobin Bart's disease with multiple limb reduction defects detected at 10 weeks of gestation, which allowed a strong presumptive diagnosis of hemoglobin Bart's disease to be made at the time of ultrasound examination. The limb defects were verified by direct visualization via needle embryoscopy. The present case suggests that sonographic identification of limb reduction defects may be a specific marker of hemoglobin Bart's disease at 10 weeks.

Adult↗