Biomedical subjects

P C Ho

Publications and source records attributed to P C Ho.

At least 19 recordsLinked to original sources

PubMed2003

Quantitation of paclitaxel in micro-sample rat plasma by a sensitive reversed-phase HPLC assay.

A sensitive high-performance liquid chromatographic (HPLC) method was developed for the determination of paclitaxel in micro-samples of rat plasma in order to study the mechanism of enhanced systemic exposure of paclitaxel co-administered with P-glycoprotein inhibitors. The assay involved solid-phase extraction procedures using 2'-methylpaclitaxel as the internal standard. Chromatographic separations were achieved using a ZORBAX ODS C18 column and mobile phase consisting of acetonitrile, methanol and ammonium acetate buffer (10 mM, pH 5.0) (48.5:16.5:35) pumped at 0.8 ml/min. The effluents were measured for UV absorption at 227 nm, with retention times of 8.5 and 11.0 min for paclitaxel and 2'-methylpaclitaxel, respectively. The chromatographic separation was excellent, with no endogenous interference. The standard curves showed a good linearity (r=0.9994) over the concentration ranges of 10-1,000 ng/ml. At 1,000 ng/ml, the absolute recoveries of paclitaxel and 2'-methylpaclitaxel are 89 and 90%, respectively. The intra- and inter-day variabilities of paclitaxel were both less than 15%. This validated method for the assay of paclitaxel in micro-sample rat plasma made it feasible to study the pharmacokinetics of the drug in a single rat.

Animals↗

PubMed2003

Amniotic fluid human chorionic gonadotrophin and alpha-fetoprotein levels in pregnancies conceived after assisted reproduction.

OBJECTIVES: To study the alteration in the second-trimester maternal serum levels of human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) in pregnancies conceived after assisted reproduction. METHODS: We compared the amniotic fluid hCG and AFP concentrations of 45 pregnancies with fresh embryo transfer and 25 pregnancies with frozen-thawed embryo transfer with 269 spontaneous pregnancies. Wilcoxon rank-sum test was used for analysis. RESULTS: The median amniotic fluid hCG MoM in pregnancies conceived after frozen-thawed embryo transfer was significantly increased to 1.41 compared to 1.00 (p = 0.01) in naturally occurring pregnancies and 0.96 (p = 0.049) in pregnancies after fresh embryo transfer. Further analysis showed that this was only observed in frozen embryos fertilized by conventional insemination with MoM of 1.59. The AFP MoMs were similar among the groups. CONCLUSIONS: The observed raised amniotic fluid hCG level in IVF-FET pregnancies may reflect the elevated maternal serum level in these pregnancies. Further studies should be directed towards exploring the underlying pathophysiology.

Adult↗

PubMed2003

Amenorrhea associated with contraception-an international study on acceptability.

Surveys undertaken in the 1970s and 1980s suggested that amenorrhea was unacceptable to most women, especially in developing countries. More recent research suggests that increasing numbers of women in the developed world prefer to menstruate less often. In a questionnaire survey of 1001 women attending family-planning clinics and 290 contraceptive providers in China, South Africa, Nigeria and Scotland, only among black women in Africa did the majority like having periods. In all other groups, most women disliked periods, which were "inconvenient" and associated with menstrual problems. Given the choice, the majority of Nigerian women would prefer to bleed monthly. Elsewhere, women would opt to bleed only once every 3 months, or not at all. In all except the Chinese centers, the majority of women would be willing to try a contraceptive which induced amenorrhea. Providers tended to overestimate the importance of regular menstruation to their clients. This is an important observation for scientists and funding agencies involved in developing new methods of contraception.

Adult↗

PubMed2003

A comparison of isosorbide mononitrate and misoprostol cervical ripening before suction evacuation.

OBJECTIVE: To compare the efficacy of a nitric oxide donor (isosorbide mononitrate) and a prostaglandin E1 analogue (misoprostol) for cervical priming before suction termination of pregnancy. METHODS: This was a randomized, double blind, placebo-controlled trial. One hundred twenty-six healthy women requesting termination of pregnancy between 9 and 12 weeks' gestation were recruited. Women were randomized into three groups: control, isosorbide mononitrate, and misoprostol. All women were given moistened intravaginal study drugs (placebo, 40 mg of isosorbide mononitrate, or 400 microg of misoprostol) 4-6 hours before suction evacuation. Side effects were assessed 3 hours after drug administration. The cervical dilatation and the cumulative force required to dilate the cervix to 8 mm were measured by a cervical tonometer before suction evacuation. Operative blood loss was measured after sieving off the products of gestation. RESULTS: There were no differences in the baseline cervical dilatation, cumulative force, and operative blood loss between the isosorbide mononitrate and placebo groups. However, women in the misoprostol group had a significantly greater cervical dilatation, required less cumulative force, and had less blood loss than women in the isosorbide mononitrate or control group. The majority (more than 80%) of women in all three groups found their cervical priming agents acceptable. CONCLUSION: Intravaginal isosorbide mononitrate was less effective than misoprostol in cervical ripening before suction termination of pregnancy.

Abortion, Induced↗

PubMed2003

Enhanced localization of osteoid osteoma with radiolabeling and intraoperative gamma counter guidance: a case report.

Osteoid osteoma is a benign bone tumor that can be removed by marginal excision. Excessive removal of reactive bone may result in significant morbidity. We made use of the highly specific radioactive technetium uptake characteristic of osteoid osteoma for its localization. Radioactive technetium (25 mCi) was injected intravenously 2 hours before surgery to a 21-year-old male patient with an osteoid osteoma over the left distal radius. Tumor tissue was localized intraoperatively by a portable hand-held radioactive gamma counter to detect a focal high intensity of radioactivity. Complete tumor removal was shown by reduction of radioactivity to background level. This was confirmed by bone scintigraphy of the specimen and the forearm immediately after surgery. The defect was packed with cancellous bone graft taken from the ipsilateral distal radius through the same wound. Postoperative recovery was very satisfactory. We found this approach useful in limiting resection margin and surgical site morbidity in resection of osteoid osteoma.

Adult↗

PubMed2003

Molecular analysis of the androgen receptor gene in Hong Kong Chinese infertile men.

PURPOSE: To investigate the relationship between CAG repeat length in the androgen receptor gene and impaired spermatogenesis in Hong Kong Chinese population. METHODS: The CAG repeat region was amplified by polymerase chain reaction (PCR) in 85 nonobstructive azoospermic or severe oligozoospermic men, and 45 fertile males. The number of CAG repeat was analyzed by DNA sequencing. Serum FSH, LH, and testosterone levels were also determined in these men. RESULTS: Among nonobstructive azoospermic males, three men (5.7%) possessed short CAG repeats (< 16), and three (5.7%) other men possessed long CAG repeats (> 30). Short CAG repeats (< 16) were also found in two severe oligozoospermic males (6.3%). The incidence of infertile men with short or long CAG repeats is significantly higher in the azoospermic group (p = 0.03) but not in the severe oligozoospermic group (p = 0.17) when compared with the fertile controls CONCLUSION: Our data suggest an association between CAG repeat lengths and impaired spermatogenesis in azoospermic males in our population.

Adolescent↗

PubMed2003

Maternal serum hCG and alpha-fetoprotein levels in pregnancies conceived after IVF or ICSI with fresh and frozen-thawed embryos.

BACKGROUND: Studies have shown that levels of serum markers of Down's syndrome were altered in pregnancies conceived after IVF, though the reason for this remains unknown. METHODS: Second-trimester maternal serum levels of hCG and alpha-fetoprotein (AFP) in pregnancies conceived with fresh and frozen-thawed embryos after assisted reproduction were compared with those conceived spontaneously. RESULTS: There were 203 pregnancies with fresh embryo transfers (130 IVF cases, 73 ICSI cases) and 98 pregnancies with frozen-thawed embryo transfers (61 IVF cases, 37 ICSI cases). The controls consisted of 17 145 spontaneous pregnancies. The median hCG multiples of the median (MoM) was significantly increased to 1.24 in 98 pregnancies conceived after frozen embryo transfer. This elevation was observed only in the IVF-frozen embryo transfer subgroup (P < 0.001), but not in the ICSI-frozen embryo transfer subgroup. The median AFP MoM for 203 pregnancies after fresh embryo transfer was 0.90. Among the subgroups, the median AFP MoM was significantly reduced to 0.90 and 0.86 in IVF-embryo transfer (P = 0.04) and ICSI-embryo transfer (P = 0.001) pregnancies respectively, and significantly raised to 1.20 in the IVF-frozen embryo transfer subgroup. CONCLUSIONS: The degree of alterations in maternal serum hCG and AFP levels varied between fresh and frozen-thawed embryos, and also between the mode of fertilization. Pregnancies resulting from ICSI or frozen embryo transfer should be regarded as distinct entities from those of IVF-embryo transfer.

Case-Control Studies↗

PubMed2003

Pre-implantation genetic diagnosis in Hong Kong.

This paper presents the first two successful cases of pre-implantation genetic diagnosis in Hong Kong and discusses the indications and the advantages over prenatal diagnosis. Patients should be informed about the procedure and extensively counselled about the possibility of misdiagnosis and the need for conventional prenatal diagnosis during pregnancy.

Adult↗

PubMed2003

Carpal tunnel release. A prospective, randomised study of endoscopic versus limited-open methods.

Endoscopic carpal tunnel release has the advantage over open release of reduced tissue trauma and postoperative morbidity. Limited open carpal tunnel release has also been shown to have comparable results, but is easier to perform and is safer. We have compared the results of both techniques in a prospective, randomised trial. Thirty patients with bilateral carpal tunnel syndrome had simultaneous bilateral release. The technique of release was randomly allocated to either two-portal endoscopic release (ECTR) or limited open release using the Strickland instrumentation (LOCTR). The results showed that the outcome was similar at follow-up of one year using both techniques. However, the LOCTR group had significantly less tenderness of the scar at the second and fourth postoperative week (p < 0.01). There was also less thenar and hypothenar (pillar) pain after LOCTR. Subjective evaluation showed a preference for LOCTR.

Adult↗

PubMed2002

Preparation and characterization of immunogens for antibody production against metanephrine and normetanephrine.

A two-step zero-length cross-linking procedure using active esters was successfully adopted for conjugating metanephrine (MN) and normetanephrine (NM) to bovine serum albumin (BSA). The protein was activated with water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in the presence of N-hydroxysulfosuccimide (sulfo-NHS), leading to the formation of active N-succinimidyl esters of some glutamic and aspartic acid carboxyls. The pertinence of this reaction for the coupling of these haptens to carboxylate groups was confirmed via reaction with a model compound, 2-hydroxybenzoic acid, and subsequent characterization using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used for the quantitative assessment of the hapten/protein ratios of these conjugates. This technique of conjugate characterization demonstrated greater resolution in molecular weight determination compared to nondenaturing polyacrylamide gel electrophoresis (native PAGE). Preliminary results from enzyme-linked immunosorbent assay (ELISA) and inhibition ELISA procedures using test antisera confirmed that the synthesized immunogens were highly antigenic and elicited specific antibody responses in BALB/c mice against the haptens.

Animal Population Groups↗

PubMed2002

Terpenes in ethanol: haloperidol permeation and partition through human skin and stratum corneum changes.

Carvacrol, linalool and alpha-terpineol (5% w/v) in 50% ethanol were used to enhance the permeation of haloperidol (HP) through human skin in vitro and their enhancement mechanism was investigated with HP-stratum corneum (SC) binding studies, fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Carvacrol followed by terpineol and linalool enhanced flux and permeability coefficient but only carvacrol provided the required plasma concentration and the permeated daily doses. All terpenes increased the activity coefficient of HP in the skin. Carvacrol increased the lag time, which could be due to slow redistribution within SC. The thermogram of hydrated SC showed two lipid endotherms T1 and T2 at 65 and 78 degrees C and protein endotherm T3 at 97 degrees C. All endotherms were absent after SC treated for 48 h with 12 ml of terpene solutions and a decrease in melting points (m.p.) of lipids with a shift of protein endotherm were observed after 12 h treatment with 7 ml of terpene solutions. Linalool and terpineol decreased the m.p. of T1 to 33 degrees C. Carvacrol increased the T1 peak area, which was attributed to lateral lipid bilayer swelling. The IR spectra showed decreases in peak areas and heights of CH2 stretchings but did not show shift of these peaks, increase in their peak widths and shift in amide bands. All the three terpenes disrupted the lipid bilayer and extracted the lipids. Moreover, carvacrol increased the partition of HP whilst linalool and terpineol fluidized the lipids at skin temperature. There could be other possible protein-terpene interactions.

Antipsychotic Agents↗

PubMed2002

Terpenes in propylene glycol as skin-penetration enhancers: permeation and partition of haloperidol, Fourier transform infrared spectroscopy, and differential scanning calorimetry.

The respective alcoholic terpenes carvacrol, linalool, and alpha-terpineol were used at 5% w/v in propylene glycol (PG) to increase the in vitro permeation of haloperidol (HP) through human skin. The possible enhancement mechanism was then elucidated with HP-stratum corneum (SC) binding studies, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The greatest increase in the permeation of HP was achieved with linalool followed by carvacrol and terpineol. HP permeation with linalool was predicted to reach a therapeutic plasma concentration and therapeutic daily-permeated amounts. Carvacrol increased lag time, which was attributed to slow redistribution of the enhancer within SC. Carvacrol increased the partition of the drug to the pulverized SC. Pure PG extracted lipids from SC but less than that achieved by the terpenes in PG. Terpenes extracted lipids to a similar extent. An increase in bilayer cohesion in the remaining lipids present in the SC could be attributed to the alignment of terpenes within the lipid bilayer. The higher permeation with linalool was attributed to its molecular orientation within the lipid bilayer. Terpenes showed different rates of SC dehydration but did not change the percentages of secondary structures of keratin.

Calorimetry, Differential Scanning↗

PubMed2002

Comparative study of the biological activity of spermatozoa-zona pellucida binding inhibitory factors from human follicular fluid on various sperm function parameters.

Previous studies showed that human follicular fluid (hFF) from gonadotrophin stimulated cycles contained two glycoproteins, named as ZIF-1 and ZIF-2, that reduced the zona binding capacity of spermatozoa. The present study showed that the spermatozoa-zona pellucida binding inhibitory activity was also present in hFF from natural cycle. Using the hemizona binding assay, the inhibitory effect of ZIF-1 on the zona binding capacity of spermatozoa was dose-dependent. The effect of ZIF-2 was also dose-dependent, in the range of 10-100 ng/ml. The inhibitory effects of both ZIF-1 and -2 increased with the duration of the spermatozoa-ZIF interaction. The effect of the former was present up to 120 min incubation, whilst that of latter occurred for the first 90 min. The zona binding inhibitory effect of ZIF-1 and -2 was additive when they were used together to treat the spermatozoa. The biological activity of ZIFs on other sperm parameters that might affect spermatozoa-zona pellucida binding was also investigated. ZIF-1 did not affect the acrosomal status of human spermatozoa while ZIF-2 significantly increased the number of acrosome reacted spermatozoa in the range of 0.1-10 microg. However, the increase in the incidence of acrosome-reacted spermatozoa after ZIF-2 treatment could not totally account the inhibitory effect of ZIF-2 on zona binding. Both glycoproteins did not affect the motility of human spermatozoa. Radioactively-labelled ZIFs bound to human spermatozoa. Unlabelled ZIF displaced the bound radioactivity of spermatozoa treated with the corresponding labelled ZIF. These suggested the presence of specific binding sites of ZIFs on human spermatozoa.

Acrosome Reaction↗

PubMed2002

A comparison of the prevalence of domestic violence between patients seeking termination of pregnancy and other general gynecology patients.

OBJECTIVES: (1) To determine and compare the prevalence of domestic violence among abortion-seeking patients with other general gynecology patients; (2) to see if a follow-up interview 6 weeks after abortion can improve the abuse disclosure rate; (3) to see if the abused victims accept direct referral to their gynecologists/social workers for help. METHODS: This is a prospective questionnaire survey in a university teaching hospital on patients seeking abortion and an approximately equal number of other general gynecology patients. Participants were interviewed by a designated project nurse in a private setting, using a structured questionnaire (Modified Abuse Assessment Screen Questionnaire) to assess the past and recent history of abuse. The interview was repeated 6 weeks after the abortion for the abortion-seeking group. RESULTS: Five hundred and one participants were interviewed, including 245 seeking abortion (TOP group) and 256 other general gynecology patients (non-TOP group). The lifetime prevalence of abuse in the TOP group (27.3%) was significantly higher than the non-TOP group (8.2%) (P<0.001). Repeating the interview 6 weeks after the abortion did not increase the disclosure rate. Most abused victims were unwilling to disclose their information of abuse to their gynecologists or social workers at the time of interview. CONCLUSIONS: Domestic violence is a significant problem among the gynecology patients, particularly those seeking abortion. A single interview prior to abortion is adequately effective for screening. However, the most effective and acceptable way of helping these victims needs to be explored further.

Abortion, Induced↗

PubMed2002

Domestic violence and postnatal depression in a Chinese community.

OBJECTIVES: To study the relationship between domestic violence and postnatal blues/depression in a Chinese community. METHODS: This was a prospective cohort study on 838 women after delivery in a local university teaching hospital. Between October, 2000 and February, 2001, all Chinese speaking women after delivery were invited to be interviewed by a designated research nurse using the Abuse Assessment Screen (AAS) to detect the incidence of domestic violence, the nature of violence and the perpetrator of abuse. Demographic data, pregnancy outcome, Stein's Daily Scoring System (SDSS) scores on day 2 or 3 postdelivery, Edinburgh Postnatal Depression Scale (EPDS) scores on day 2 or 3 postdelivery, 1-2 days after discharge from hospital and at 6 weeks postdelivery were compared between the abused and non-abused groups using Student's t-test, chi(2)-test and Fisher's exact test as appropriate. RESULTS: A total of 139 women (16.6%) had been abused in the last year (the abused group). Of these, 87 (10.4%) had been abused during the current pregnancy. The nature of abuse was mainly verbal. Fourteen women (1.7%) had been sexually abused in the last year. The husband/boyfriend, mother-in-law and employer/colleague were the most common perpetrators of abuse. Socio-demographic factors did not differ between the two groups except that pregnancy was more likely to be unplanned in the abused group (P=0.002). The pregnancy outcome did not differ. However, the abused group had significantly higher SDSS and EPDS scores at all stages of screening (P=0.003, P=0.000, P=0.010 and P=0.001, respectively). CONCLUSION: The findings supported our hypothesis that the effect of domestic violence on Chinese pregnant women is mainly on their psychological well-being.

Adult↗

PubMed2002

A comparative study of Y chromosome microdeletions in infertile males from two Chinese populations.

PURPOSE: To compare the prevalence and type of Y-microdeletions in Hong Kong and Shanghai men with severe male-factor infertility. METHODS: Seven Y-linked sequence tagged site (STS) primers and seven gene-specific primers were screened in 293 infertile males (139 from Hong Kong and 154 from Shanghai) and 161 fertile men (61 from Hong Kong and 100 from Shanghai). Serum FSH, LH, and testosterone levels were also measured in these men. RESULTS: The incidence of Yq microdeletions in nonobstructive azoospermic men from Hong Kong (8.5%) and Shanghai (6%) was similar. Yq microdeletions were observed in severe oligospermic patients (8.5%) from Hong Kong but not from Shanghai. Among the 9 Hong Kong men with Y-microdeletions, 8 had AZFc deletion and one had AZFb deletion. In contrast, 6 of 9 men from Shanghai with Y-microdeletions had AZFb deletion. The incidence of AZFb deletion among Y-microdeleted men was statistically different between the two populations. Two of the men with AZFb deletion also had AZFa and AZFc deletions. CONCLUSIONS: Regional variations in the type of Y-microdeletion existed between Hong Kong and Shanghai infertile males.

Adult↗

PubMed2002

Gender selection in China: its meanings and implications.

With the advancement of assisted reproduction technologies, people are offered wider choices to choose the gender of their offspring and to construct 'ideal-typed' families with specific gender structure. Gender selection is welcomed by many societies with gender-specific preference, especially those patriarchal societies such as Chinese communities. It is not only a medical procedure but also a social orientation, which reveals much of the underlying preference towards gender. This paper explores the cultural dimensions to gender selection and its psychosocial meanings and implications in Chinese societies, especially after the establishment of One Child Policy in China. Problems associated with son preference in the culture with strong gender stereotyping are addressed. We believe that gender selection for social reasons should not be allowed since undesirable outcomes will be resulted under such strict population control program.

China↗

PubMed2002

Evaluation of cycle-to-cycle variation of endometrial responsiveness using transvaginal sonography in women undergoing assisted reproduction.

OBJECTIVES: To investigate the variation of endometrial responsiveness between cycles within the same women undergoing assisted reproduction. METHODS: The sonographic endometrial thickness in ovarian stimulation cycles was compared with that of subsequent natural cycles. One hundred and thirty-six ovarian stimulation cycles of in-vitro fertilization and embryo transfer were evaluated. Women who did not conceive in in-vitro fertilization cycles were subsequently seen in natural cycles (n = 97) or the next in-vitro fertilization cycle (n = 39). Based on a receiver-operating characteristics (ROC) curve using endometrial thickness to predict pregnancy, the first in-vitro fertilization cycles were classified according to the endometrial thickness as optimal (> 8 mm) in 98 cycles, or suboptimal (< or = 8 mm) in 29 cycles. Similarly, spontaneous cycles were classified as suboptimal (< or = 7 mm) in 28 cycles and optimal (> 7 mm) in 69 cycles. RESULTS: The pregnancy rates were significantly lower (P < 0.05; Fisher's Exact test) in the suboptimal group in both the in-vitro fertilization and frozen embryo transfer cycles. There was a strong correlation (r2 = 0.745) and a significant difference (P < 0.001; Wilcoxon signed rank sum test) between the endometrial thickness of stimulation and natural cycles. CONCLUSION: It is possible to predict the occurrence of optimal or suboptimal endometrial response in natural cycles of women, after evaluation in stimulated cycles, with a high degree of reliability. Risk of implantation failure can be identified before subsequent treatment cycles and adjuvant therapeutic strategies may be planned to improve the endometrial response before embryo transfer.

Adult↗