High Resolution Prediction of Calcium-Binding Sites in 3D Protein Structures Using FEATURE

Metal-binding proteins are ubiquitous in biological systems ranging from enzymes to cell surface receptors. Among the various biologically active metal ions, calcium plays a large role in regulating cellular and physiological changes. With the increasing number of high-quality crystal structures of proteins associated with their metal ion ligands, many groups have built models to identify Ca(2+) sites in proteins, utilizing information such as structure, geometry, or homology to do the inference. We present a FEATURE-based approach in building such a model and show that our model is able to discriminate between nonsites and calcium-binding sites with a very high precision of more than 98%. We demonstrate the high specificity of our model by applying it to test sets constructed from other ions. We also introduce an algorithm to convert high scoring regions into specific site predictions and demonstrate the usage by scanning a test set of 91 calcium-binding protein structures (190 calcium sites). The algorithm has a recall of more than 93% on the test set with predictions found within 3 Å of the actual sites.

Knowledge-based fragment binding prediction

Target-based drug discovery must assess many drug-like compounds for potential activity. Focusing on low-molecular-weight compounds (fragments) can dramatically reduce the chemical search space. However, approaches for determining protein-fragment interactions have limitations. Experimental assays are time-consuming, expensive, and not always applicable. At the same time, computational approaches using physics-based methods have limited accuracy. With increasing high-resolution structural data for protein-ligand complexes, there is now an opportunity for data-driven approaches to fragment binding prediction. We present FragFEATURE, a machine learning approach to predict small molecule fragments preferred by a target protein structure. We first create a knowledge base of protein structural environments annotated with the small molecule substructures they bind. These substructures have low-molecular weight and serve as a proxy for fragments. FragFEATURE then compares the structural environments within a target protein to those in the knowledge base to retrieve statistically preferred fragments. It merges information across diverse ligands with shared substructures to generate predictions. Our results demonstrate FragFEATURE's ability to rediscover fragments corresponding to the ligand bound with 74% precision and 82% recall on average. For many protein targets, it identifies high scoring fragments that are substructures of known inhibitors. FragFEATURE thus predicts fragments that can serve as inputs to fragment-based drug design or serve as refinement criteria for creating target-specific compound libraries for experimental or computational screening.

High precision prediction of functional sites in protein structures

We address the problem of assigning biological function to solved protein structures. Computational tools play a critical role in identifying potential active sites and informing screening decisions for further lab analysis. A critical parameter in the practical application of computational methods is the precision, or positive predictive value. Precision measures the level of confidence the user should have in a particular computed functional assignment. Low precision annotations lead to futile laboratory investigations and waste scarce research resources. In this paper we describe an advanced version of the protein function annotation system FEATURE, which achieved 99% precision and average recall of 95% across 20 representative functional sites. The system uses a Support Vector Machine classifier operating on the microenvironment of physicochemical features around an amino acid. We also compared performance of our method with state-of-the-art sequence-level annotator Pfam in terms of precision, recall and localization. To our knowledge, no other functional site annotator has been rigorously evaluated against these key criteria. The software and predictive models are incorporated into the WebFEATURE service at http://feature.stanford.edu/wf4.0-beta.

Bioinformatics and variability in drug response: a protein structural perspective

Marketed drugs frequently perform worse in clinical practice than in the clinical trials on which their approval is based. Many therapeutic compounds are ineffective for a large subpopulation of patients to whom they are prescribed; worse, a significant fraction of patients experience adverse effects more severe than anticipated. The unacceptable risk-benefit profile for many drugs mandates a paradigm shift towards personalized medicine. However, prior to adoption of patient-specific approaches, it is useful to understand the molecular details underlying variable drug response among diverse patient populations. Over the past decade, progress in structural genomics led to an explosion of available three-dimensional structures of drug target proteins while efforts in pharmacogenetics offered insights into polymorphisms correlated with differential therapeutic outcomes. Together these advances provide the opportunity to examine how altered protein structures arising from genetic differences affect protein-drug interactions and, ultimately, drug response. In this review, we first summarize structural characteristics of protein targets and common mechanisms of drug interactions. Next, we describe the impact of coding mutations on protein structures and drug response. Finally, we highlight tools for analysing protein structures and protein-drug interactions and discuss their application for understanding altered drug responses associated with protein structural variants.

Comparative modeling: the state of the art and protein drug target structure prediction

The goal of computational protein structure prediction is to provide three-dimensional (3D) structures with resolution comparable to experimental results. Comparative modeling, which predicts the 3D structure of a protein based on its sequence similarity to homologous structures, is the most accurate computational method for structure prediction. In the last two decades, significant progress has been made on comparative modeling methods. Using the large number of protein structures deposited in the Protein Data Bank (~65,000), automatic prediction pipelines are generating a tremendous number of models (~1.9 million) for sequences whose structures have not been experimentally determined. Accurate models are suitable for a wide range of applications, such as prediction of protein binding sites, prediction of the effect of protein mutations, and structure-guided virtual screening. In particular, comparative modeling has enabled structure-based drug design against protein targets with unknown structures. In this review, we describe the theoretical basis of comparative modeling, the available automatic methods and databases, and the algorithms to evaluate the accuracy of predicted structures. Finally, we discuss relevant applications in the prediction of important drug target proteins, focusing on the G protein-coupled receptor (GPCR) and protein kinase families.

Remote thioredoxin recognition using evolutionary conservation and structural dynamics

The thioredoxin family of oxidoreductases plays an important role in redox signaling and control of protein function. Not only are thioredoxins linked to a variety of disorders, but their stable structure has also seen application in protein engineering. Both sequence-based and structure-based tools exist for thioredoxin identification, but remote homolog detection remains a challenge. We developed a thioredoxin predictor using the approach of integrating sequence with structural information. We combined a sequence-based Hidden Markov Model (HMM) with a molecular dynamics enhanced structure-based recognition method (dynamic FEATURE, DF). This hybrid method (HMMDF) has high precision and recall (0.90 and 0.95, respectively) compared with HMM (0.92 and 0.87, respectively) and DF (0.82 and 0.97, respectively). Dynamic FEATURE is sensitive but struggles to resolve closely related protein families, while HMM identifies these evolutionary differences by compromising sensitivity. Our method applied to structural genomics targets makes a strong prediction of a novel thioredoxin.

Continuing professional development--a surrogate for recertification?

Medical practitioners are certified as competent when they graduate from medical schools. They are certified as competent specialists after they have completed the various specialist training programmes. To maintain specialist status, the commonest requirement is mandatory continuing professional development (CPD), and in some places, continuing medical education (CME), which has been perceived by some as inadequate because it is passive, and skills and professionalism are excluded. In order to sustain the standard of medical practice and to assure quality of care, some registration organisations require that recertification be conducted not only through CPD, but written and oral examinations as well. In this manner, the criteria for quality medical care, which are evidence of professional standing, lifelong learning and self-assessment, cognitive functioning and evaluation of performance in practice, are fulfilled. CPD should involve educational activities of the medical practitioner's choice and be capable of enhancing his or her practice at any particular period of time. Well-structured, well-designed and validated CPD can be considered as a surrogate for recertification.

The use of the Minimum Data Set. Home Care in a case management project in Hong Kong

130 hospital-discharged elderly patients received our comprehensive assessment by using a Chinese Minimum Data Set-Home Care (MDS-HC). Our case manager developed and implemented care plans with reference to the computer-generated Clients Assessment Protocols. Results showed that the MDS-HC was sensitive to identify elderly persons' holistic needs, and helpful in formulating all-inclusive care plans.

Psychosocial adjustment in gynecologic cancer survivors: a longitudinal study on risk factors for maladjustment

OBJECTIVE

The objective was to describe the change in psychosocial state over time and to identify risk factors for maladjustment in gynecologic cancer survivors. Awareness of these issues is important for planning supportive care services for cancer patients.

METHODS

A longitudinal prospective study of patients with newly diagnosed gynecologic cancer using individual patients as their own control was performed. Patients were interviewed after confirmation of the diagnosis and were reassessed at 6 and 18 months after completion of treatment and with no evidence of recurrent disease. Psychological adjustment was measured by self-rating on self-esteem, outlook on life, self-role, and femininity. Neuroticism and anxiety were assessed using a neuroticism score and the Hamilton Anxiety Scale. Depressive symptoms were questioned directly. Social adjustment was assessed by changes in working capacity or work status, leisure activity, marital relationship, and sexual activity.

RESULTS

Seventy-four women participated. Adjustment problems did not occur in the majority of patients. Psychosocial adjustment was different for patients receiving different types of treatments. Improvement in feminism (P = 0.050) and neuroticism (P = 0.010) was observed for patients receiving chemotherapy and deterioration was observed in patients treated with surgery. Deterioration in neuroticism was associated with lower education level (P = 0.032). With religious belief, there was better family support and more significant improvement in social activity (P = 0.038).

CONCLUSION

Most patients adapted well. Patients at risk for psychosocial maladjustment include those who are treated surgically, less educated, and without religious belief.

The profile of bone mineral density in chinese women: its changes and significance in a longitudinal study

Bone mineral density (BMD) has been shown to be different in different ethnic groups. When lifestyle and diet evolve, there is a possibility of a change in the normal reference BMD values within an ethnic group over a period of time. As the osteoporotic risk uses the T-score as the bench mark, it is pertinent to evaluate whether such changes do occur. Two measurements, 5 years apart, of the BMD of the spine and the hip were made in a cohort of Chinese women in Hong Kong. A kernel function smoothing method, a nonparametric statistical method, was employed to present the BMD data. The greatest rate of bone loss was found to occur between 50 and 59 years of age, but this rate of loss was reduced from age 60 onwards. The BMD values obtained in these two measurements were different from the previous studies in the same population and were found to be higher at the lumbar spine and neck of femur in women over 65 years of age. Even within the cohort, there seemed to be a reduction in the BMD values of the hip in a span of 5 years, although the differences were statistically insignificant. These studies suggest that BMD values could change in a population for a variety of possible reasons. Hence, the reference BMD values might need to be evaluated at regular intervals for the T-score to be meaningful.

Plasma melatonin profile and hormonal interactions in the menstrual cycles of anovulatory infertile women treated with gonadotropins

The patterns of plasma melatonin, gonadotropins, sex steroids and prolactin were studied in anovulatory infertile females undergoing ovulation induction with hMG/hCG. Melatonin levels were found to fluctuate during the menstrual cycle of these subjects with a nadir at mid-cycle and peak occurring at the early follicular/late luteal phases of the cycle (p < 0.05). Melatonin correlated negatively with estradiol during the follicular phase (r=-0.5180, p < 0.05) and positively with LH (5 + 0.6321, p < 0.05) in the luteal phase, respectively. Correlational analyses by partial and multiple correlations suggest that the effects of estradiol and LH on melatonin in the follicular phase are interdependent whereas the effect of LH on melatonin in the luteal phase is independent of the effects of other hormones. The results suggest that hormonal interactions and phases of the cycle are important variables contributing to the fluctuations in melatonin levels during the menstrual cycle.

Prevention of postoperative nausea and vomiting in gynaecological laparotomies: a comparison of tropisetron and ondansetron

In a randomized, double-blind study, the antiemetic efficacy of a single bolus of tropisetron 5 mg (group T, 37 patients), ondansetron 4 mg (group O, 39 patients) or saline (group C, 45 patients) given at induction was compared in a homogeneous group of 121 patients undergoing gynaecological laparotomy and receiving postoperative patient-controlled intravenous morphine for 24 to 48 hours. Fewer group T and group O patients developed severe nausea compared to group C (P < 0.01, log rank test in Kaplan-Meier analysis). Group T patients also had lower nausea scores than group O at 8 to 16h (P < 0.05). The overall incidences of severe nausea in groups T, O, and C were 5.4%, 17.9%, and 44.4% respectively (P < 0.001, group T vs group C; P < 0.05 group O vs group C). In conclusion, the 5-hydroxytryptamine 3 receptor antagonists tropisetron and ondansetron were superior to placebo in preventing PONV.

Evaluation of a new calcaneal quantitative ultrasound system and determination of normative ultrasound values in southern Chinese women

Quantitative ultrasound (QUS) assessment at the calcaneus has been found to be a safe and reliable method for evaluating skeletal status. The present study aimed at evaluating the precision of the Sahara bone ultrasound densitometer and to determine the normative QUS data in healthy southern Chinese women. Broadband ultrasound attenuation (BUA), speed of sound (SOS) and qualitative ultrasound index (QUI) were determined. The long-term in vitro precision of the Sahara machine over 6 months was 4.6% for BUA and 0.39% for SOS. The short-term in vivo precision was 3.2 +/- 1.3% for BUA, 0.3 +/- 0.2% for SOS and 1.8 +/- 1.0% for QUI. The standardized precision for BUA, SOS and QUI was 4.4, 3.8 and 2.2 respectively. The normative data were determined in 1086 healthy subjects. Postmenopausal women had significantly lower BUA, SOS and QUI levels than the premenopausal women. Significant negative correlations were observed between QUS indices and age. Bone mineral density (BMD) assessments was performed on 349 of these subjects. BUA correlated significantly with lumbar spine BMD (r = 0.326) and femoral neck BMD (r = 0.395). Similar correlations were observed between SOS, QUI and BMD, with r values ranging between 0.446 to 0.522. Despite the fact that Chinese women have significantly lower BMD values than Caucasian women, the mean BUA values for pre- and postmenopausal Chinese women (73 +/- 18 and 59 +/- 18 dB/MHz respectively) were almost the same as those reported for Caucasian women. These normative data will be useful in the assessment of southern Chinese women with fracture risk.

Quantitative ultrasound and symptomatic vertebral fracture risk in Chinese women

Quantitative ultrasound (QUS) is emerging as a simple, inexpensive and noninvasive method for assessing bone quality and assessing fracture risk. We assessed the usefulness of a contact calcaneal ultrasonometer by studying normal premenopausal women (group I, n = 53), normal postmenopausal women (group II, n = 198), and osteoporotic women without (group III, n = 141) and with vertebral fractures (group IV, n = 53). The osteoporotic subjects had a T-score of the spine or hip neck bone mineral density (BMD) <-2.5 based on the local Chinese peak young mean values. When compared with postmenopausal controls, mean broadband ultrasound attenuation (BUA), speed of sound (SOS), and quantitative ultrasound index (QUI) were 26%, 2.1% and 25% lower in women with vertebral fractures (p all <0.005). The correlation coefficients between QUS parameters and BMD of the spine and hip ranged between 0.4 and 0.5. The ability of the QUS to discriminate between patients groups was determined based on the mean value of normal premenopausal women in group I. The mean T-score for women with fractures was -2.87 +/- 1.02 for BUA, -2.54 +/- 0.79 for SOS, -3.17 +/- 0.70 for QUI, -2.65 +/- 0.86 for L2-4 BMD and -2.53 +/- 0.66 for hip neck BMD. After adjustment for age and body mass index, the odds ratio of vertebral fracture was 1.71 (95% CI 1.2-2.6) for each 1 SD reduction in BUA, 2.72 (1.3-5.3) for SOS, 2.58 (1.4-4.6) for QUI, 2.33 (1.6-3.3) for L2-4 BMD, 2.09 (1. 37-3.20) for femoral neck BMD and 1.88 (1.34-2.92) for total hip BMD. The association between the QUS parameters and vertebral fracture risk persisted even adjustment for BMD. The area under the receiver operating characteristic curve for BUA for vertebral fracture was 0. 92, for SOS, QUI, L2-4 BMD and femoral neck BMD was 0.95, and for total hip was 0.91.

Levonorgestrel intrauterine device in the treatment of menorrhagia in Chinese women: efficacy versus acceptability

Ten Chinese women who had menorrhagia without organic cause and suffered from anaemia were treated with levonorgestrel intrauterine device for a total of 129 woman-months. There was a 54%, 87% and 95% reduction in menstrual blood loss at the first, third and sixth month of treatment when compared with the pretreatment cycle. These percentages of reduction were statistically significant, with p values of 0.004, 0.03 and 0.008, respectively. There was a median increase in menstrual cycle length of 12 days in nine months. Fifteen percent of the menstrual cycles were longer than 60 days. The total bleeding days increased by 4 days at the third menstrual cycles, but reduced to a median of 6 days at 6 months. Seventy-six percent of the menstrual bleeding was in the form of spotting. These Chinese women accepted such menstrual alterations. There was no hormonal side effects. All women preferred the device to hysterectomy. Levonorgestrel intrauterine device appeared to be an effective and acceptable treatment for menorrhagia in perimenopausal Chinese women.

The climacteric of Chinese factory workers

Chinese factory workers (427) mainly of Fujian origin were found to have few climacteric symptoms. Of these, 65% and 50% reported having no circulatory and nervosity symptoms, respectively. Only 18% of women experienced hot flushes. The climacteric symptoms were more pronounced at the perimenopausal period (P < 0.001) when these women experienced more irregular menstruation. Low socio-economic status and educational level did not have adverse effects on the symptom reporting. High parity and employment may be positive factors in this period of change of life. A majority of women (74%) felt that the climacteric and menopause is a natural process which caused them no concern. Of those who were still menstruating 80% did not anticipate that they would have problems with the climacteric and menopause. These women's different climacteric pattern could be related to their introspective abilities to cope adequately or in an impersonal manner.

Psychosocial study on Hong Kong Chinese with gynecological cancer

Psychosocial support and adjustment to cancer in 115 Chinese patients with gynecological malignancies were studied by interviews using semi-structured and structured questionnaires before commencement of treatment. Ninety per cent of patients had emotional support with 72% coming from family members, while 77% of the patients said that they were clearly informed of their diagnosis. The majority of our patients (63%) did not wish to see a counsellor. Psychological outcome of the patients was good, with less than 21% having expression of anxiety or depression. Social adjustment was less favorable; 42% of women had a reduction in leisure activity. The majority of married couples maintained a good marital relationship even though 78% had reduction or cessation of their sexual activity. Good emotional support was associated with fewer neurotic symptoms. Though there was no statistical significance demonstrated, the good psychosocial support and the favorable psychological outcome in this group of patients indicated the likelihood of a positive relationship between the two.

Further acceptability evaluation of RU486 and ONO 802 as abortifacient agents in a Chinese population

Of 144 consecutive women who requested early induced abortion, 99 (68.7%) and 45 (31.3%) women chose RU486 combined with ONO 802 (medical method) and suction evacuation (surgical method), respectively. Logistic regression analysis of covariates showed that age and marital status were significantly correlated with the acceptability and hence the choice of the medical method. There were also more working women in this medical group. Previous experience of induced abortion had no influence on the current choice of the abortion method. This group of women appeared to have a tendency of treating their disease with medication rather than with surgery if the condition would allow. They expressed fear about surgery. The long induction-abortion interval of three days will have to be tolerated, but the duration of bleeding should be minimised in order to improve the acceptability of the drug. RU486 is an alternative abortion method which should be made widely available.

The value of transabdominal pelvic ultrasonography in monitoring of ovulation induction with gonadotropins

Seventy-five patients with a total of 306 human menopausal gonadotropin treatment cycles over the period 1984-1989 were analysed retrospectively to evaluate the value of transabdominal pelvic ultrasonography in prevention of complications arising from ovulation induction with human menopausal gonadotropins. There were 60 pregnancies giving a pregnancy rate of 19.6% per cycle. There was positive correlation between the number of follicles > or = 14 mm in mean diameter and the incidence and degree of hyperstimulation (p < 0.005) as well as the incidence of multiple pregnancies (p < 0.01). Ultrasonography is a useful adjunct for monitoring in such a program.

Lymphocyte subsets and serum immunoglobulins in patients with premature ovarian failure before and after oestrogen replacement

We have previously demonstrated that in patients with oestrogen deficiency, there was a significant reduction in the ratio of CD4+ to CD8+ lymphocytes. To test our hypothesis that oestrogen deficiency was the cause of the changes in lymphocyte subsets, we have studied the lymphocyte subsets and serum immunoglobulin levels in 35 patients with idiopathic premature ovarian failure before and after oestrogen replacement therapy. Before oestrogen replacement the lymphocyte subsets in peripheral blood were enumerated with indirect immunofluorescence techniques using monoclonal antibodies. The serum immunoglobulins (Ig) G, A and M were measured with nephelometry. After oestrogen replacement therapy, the tests were repeated around day 7-11 of the 2nd, 4th and 24th month. There was no significant change in any of these parameters by the 2nd or 4th months. After 2 years of oestrogen replacement, there was a significant decrease in the percentage of CD8+ cells, a significant increase in the CD4:CD8 ratio and a significant increase in the mean serum IgG concentration. There was no significant change in the other parameters. Our results support the hypothesis that oestrogen deficiency is the cause for the changes in the lymphocyte subsets.

Retinoic acid can be produced from excentric cleavage of beta-carotene in human intestinal mucosa

The hypothesis that retinoic acid (RA) is produced from the excentric cleavage of beta-carotene was tested in human intestinal homogenates in vitro. Significant amounts of RA were identified by HPLC and derivatization after incubation of intestinal mucosal homogenates with retinal, beta-carotene, or beta-apocarotenals at 37 degrees C for 60 min. RA formation was inhibited, in a dose-dependent fashion, when retinal was incubated in the presence of 0.1-3.0 mM citral (3,7-dimethyl-2,6-octadienal) under identical experimental conditions. The formation of RA from both beta-carotene and beta-apocarotenals was dose and time dependent and RA was the major metabolite of both beta-apo-8'-carotenal and beta-apo-12'-carotenal after the incubation. However, citral (0.1 to 4 mM) did not inhibit the formation of beta-apocarotenals and RA from 2 microM beta-carotene (P greater than 0.05), which proves the existence of an excentric cleavage mechanism for beta-carotene conversion into retinoids. Furthermore, RA formation from both beta-apo-8'-carotenal and beta-apo-12'-carotenal in human intestinal homogenate occurred in the presence of citral, which demonstrates that RA can be produced from excentric cleavage of beta-carotene via a series of beta-apocarotenals as intermediates.

A pilot study of acceptability of RU486 and ONO 802 in a Chinese population

RU486 and ONO 802 in combination have been shown to be effective in early termination of pregnancy. Anecdotal information suggests that Chinese women have been using herbs to induce abortion, believing that such medication and means of abortion is less harmful to the body than surgery. Hence, a medical means of abortion using RU486 and ONO 802 may be the method of choice for some Chinese women. A pilot study involving 42 Chinese women in Hong Kong was conducted to explore the reasons for acceptance or refusal of RU486 and ONO 802 as abortifacient agents. It was found that more single women chose the medical method for abortion, the main reasons being fear of trauma to the body due to surgery and the feeling of having undergone menstrual regulation rather than having had an abortion with the medical method. Those who refused the treatment were worried about the efficacy and side effects of the new drugs and the long induction-abortion interval. There were 3 failures in the medical group of 23 women. All these 23 women were gland they had chosen the medical abortion method. Twenty-one out of the 23 women said they would choose the same abortion method again. The practice of the use of Chinese herbs was not more common in this group of women as compared to women who did not choose this method of abortion.

Characterization of beta-apo-13-carotenone and beta-apo-14'-carotenal as enzymatic products of the excentric cleavage of beta-carotene

Two new products from the incubation of beta-carotene with intestinal mucosa homogenates of human, monkey, ferret, and rat were isolated using high-performance liquid chromatography (HPLC). Identification by comparing retention times in HPLC, by monitoring ultraviolet/visible spectra, by reduction to corresponding alcohol, by oxime formation, and by mass spectrometry demonstrated that they are beta-apo-13-carotenone and beta-apo-14'-carotenal. These compounds were not found in incubations done without intestinal homogenates or with disulfiram as an inhibitor. Under standard incubation conditions, these products increased linearly for 60 min and up to a protein concentration of 1.5 mg/mL and increased along with increasing concentrations of beta-carotene. Therefore, they are enzymatic cleavage products from beta-carotene. The formation of the beta-apo-13-carotenone and beta-apo-14'-carotenal provides direct evidence for an enzymatic excentric cleavage mechanism.

Lymphocyte subsets in patients with oestrogen deficiency

We have previously shown that in patients with idiopathic premature ovarian failure there were significant changes in lymphocyte subsets. To test our hypothesis that these changes were due to oestrogen deficiency we studied lymphocyte subsets in patients with oestrogen deficiency due to other causes. Blood was taken for serum oestradiol, lymphocyte counts and lymphocyte subset counts (CD2+, CD4+, CD8+ and B cells) before oestrogen replacement in 19 patients with gonadal dysgenesis, 22 patients with hypothalamic-pituitary failure and 24 healthy female control subjects. The CD4:CD8 ratio in both groups of patients was significantly lower than that in the normal control subjects while the percentages and counts of lymphocytes and CD8+ cells were significantly higher. There was a significant positive correlation between the serum oestradiol level and the CD4:CD8 ratio. These findings support the hypothesis that the changes in lymphocyte subsets are due to oestrogen deficiency.

Enzymatic conversion of beta-carotene into beta-apo-carotenals and retinoids by human, monkey, ferret, and rat tissues

Whether the conversion of beta-carotene into retinoids involves an enzymatic excentric cleavage mechanism was examined in vitro with homogenates prepared from human, monkey, ferret, and rat tissue. Using high-performance liquid chromatography, significant amounts of beta-apo-12'-, -10'-, and -8'-carotenals, retinal, and retinoic acid were found after incubation of intestinal homogenates of the four different species with beta-carotene in the presence of NAD+ and dithiothreitol. No beta-apo-carotenals or retinoids were detected in control incubations done without tissue homogenates. The production of beta-apo-carotenals was linear for 30 min and up to tissue protein concentrations of 1.5 mg/ml. The rate of formation of beta-apo-carotenals from 2 microM beta-carotene was about 7- to 14-fold higher than the rate of retinoid formation in intestinal homogenates, and the rate of beta-apo-carotenal production was fivefold greater in primate intestine vs rat or ferret intestine (P less than 0.05). The amounts of beta-apo-carotenals and retinoids formed were markedly reduced when NAD+ was replaced by NADH, or when dithiothreitol and cofactors were deleted from the incubation mixture. Both beta-apo-carotenal and retinoid production from beta-carotene were inhibited completely by adding disulfiram, an inhibitor of sulfhydryl-containing enzymes. Incubation of beta-carotene with liver, kidney, lung, and fat homogenates from each species also resulted in the appearance of beta-apo-carotenals and retinoids. The identification of three unknown compounds which might be excentric cleavage products is ongoing. These data support the existence of an excentric cleavage mechanism for beta-carotene conversion.

13-cis-retinoic acid is an endogenous compound in human serum

The occurrence of 13-cis-retinoic acid as an endogenous component in human serum has been confirmed by cochromatography with standards in both normal-phase and reverse-phase high-performance liquid chromatographic (HPLC) system, by the lambda max of its UV spectrum recorded simultaneously with the HPLC run, and by chromatography of its methyl derivative. The method using solid-phase extraction followed by a gradient reverse-phase HPLC procedure with an internal standard and sensitive UV detector, provides an efficient and sensitive technique for the separation and quantification of serum 13-cis- and all-trans-retinoic acid. Serum levels of 13-cis- and all-trans-retinoic acid in 26 fasting volunteers ranged from 1.0 to 2.2 ng/ml (mean +/- SEM = 1.4 +/- 0.3 ng/ml) and from 1.1 to 1.9 ng/ml (mean +/- SEM = 1.4 +/- 0.2 ng/ml), respectively. The levels determined by a liquid-liquid double-phase extraction method were 90% higher in both 13-cis- and all- trans-retinoic acid than those from a solid-phase extraction. Human small intestine can isomerize all-trans-retinoic acid. 13-cis-Retinoic acid is the predominant cis isomer after incubation of intestinal mucosa homogenates with all-trans-retinoic acid. Moreover, the concentration of retinoic acid in serum is related to diet in that the level of total retinoic acid was 36% higher (n = 10) 2 h after a nonstandard breakfast than in fasting subjects.

Rabbits fed on beta-carotene have higher serum levels of all-trans retinoic acid than those receiving no beta-carotene

The aim of the present work was to determine the effect of giving increasing doses of supplements of beta-carotene on serum retinoic acid levels in rabbits. Four groups of 7-week-old female rabbits were fed for 9 weeks on a pelleted diet containing 1.72 mg vitamin A as retinyl acetate/kg and including control gelatin beadlets devoid of beta-carotene or 1, 2 or 4 mg beta-carotene/kg body-weight per d. Serum was collected at 3, 6 and 9 weeks after the beginning of the experiment and the concentration of all-trans retinoic acid was determined by a gradient reverse-phase high-performance liquid chromatography system following a double-phase extraction. The average concentration of retinoic acid in serum of the combined control and 1 mg beta-carotene/kg groups was 3.80, 3.06 and 2.40 nM at 3, 6 and 9 weeks respectively. The concentrations of retinoic acid in serum of the combined 2 and 4 mg beta-carotene/kg groups were 4.80 nM (P less than 0.05), 3.76 nM (not significant) and 4.90 nM (P less than 0.005) at 3, 6 and 9 weeks respectively. A SAS (SAS Institute Inc., 1985) general linear model repeated-measures analysis of variance revealed that the effects of treatment (P less than 0.01), time (P less than 0.05) and treatment x time interaction (P less than 0.05) were statistically significant. It is concluded that giving beta-carotene is associated with higher concentrations of all-trans retinoic acid in the serum of rabbits than in those receiving no beta-carotene.

Gonadal dysgenesis: a review of 15 years' management

Fifteen years' experience in a Menstrual Disorder Clinic revealed that gonadal dysgenesis was the commonest cause of primary amenorrhoea. Investigations using Barr Body study and laparoscopic examination were unsatisfactory and inaccurate. The invasive nature of laparoscopy was the likely principal cause for the high default rate in the early years of the Clinic. The availability of hormone radioimmunoassay and cytogenetic study has improved the diagnostic acuity. Gonadal malignancy associated with the "Y" chromosome could also be identified at its early stage. Oestrogen replacement therapy has been found to be beneficial and is associated with little side effects and no endometrial pathology has been identified.

Non-surgical sterilization using phenol-mucilage: acceptability versus efficacy

Sterilization has become a popular means of birth control and many methods have been developed to meet the needs of different groups of women. In a pilot study, non-surgical sterilization using phenol-mucilage was found to be extremely acceptable to a group of Chinese women despite its failure rate. The method is simple, safe and inexpensive. It is suggested that this method would be suitable for women who are afraid of surgical sterilization.

Further evaluation of first morning urinary oestrogen in monitoring gonadotrophin therapy

Efficient gonadotrophin therapy requires both biochemical and ultrasonic measurements of ovarian response. Biochemical monitoring can take the form of measurement of plasma oestradiol levels or urinary oestrogen excretion. Levels of first morning urinary oestrogen to creatinine ratio have been shown to correlate well with 24-hour total urinary oestrogen excretion. Such urine collection is not cumbersome and is less invasive than daily venepuncture. Eighty gonadotrophin treatment cycles were evaluated by first morning urinary oestrogen to creatinine ratio and ultrasound scanning of follicles. Analysis confirmed that the ratio correlated significantly both with plasma oestradiol and 24-hour urinary oestrogen levels. The administration of the ovulating dose of human chorionic gonadotrophin depended primarily on ultrasonic demonstration of the presence of mature follicles in the ovaries. There was no increased incidence of multiple gestation or hyperstimulation syndrome in 135 treatment cycles. It is concluded that first morning urinary oestrogen to creatinine ratio is a convenient and cheap method of efficient biochemical monitoring of ovarian response to gonadotrophin therapy.

Immunologic studies in patients with premature ovarian failure

Tests for a range of autoantibodies, and counts of lymphocytes, B cells, T cells, and T cell subsets were performed in 45 Chinese patients with premature ovarian failure and 45 age-matched normal control subjects. Eight patients (18%) were positive for at least one autoantibody. Only one patient was positive for antiovarian antibody. Patients with autoantibodies had a significantly higher percentage of circulating B cells. The lymphocyte, T cell, CD4+, and CD8+ counts in patients with premature ovarian failure were significantly higher than those in the control group, but the CD4:CD8 ratio was significantly lower in women with premature ovarian failure. There was a significant negative correlation between plasma estradiol levels and CD8+ counts, and a significant positive correlation between plasma estradiol levels and CD4:CD8 ratios. The changes in lymphocytes and lymphocyte subpopulations in premature ovarian failure may be due to estrogen deficiency.

Diagnosis of early pregnancy by enzyme immunoassay of Schwangerschafts-protein 1

Serum Schwangerschafts-protein 1 (SP1) and beta subunit of human chorionic gonadotropin (beta-hCG) were measured by enzyme immunoassay and radioimmunoassay, respectively, in the follicular phase and luteal phase of 50 human menopausal gonadotropin treatment cycles. SP1 could be detected in 63% of blood samples taken in the follicular phase up to the level of 1.56 micrograms/l. Using a cutoff level of 2 micrograms/l, SP1 could be used to diagnose pregnancy 16 to 25 days after the ovulating dose of hCG. The serum SP1 level is not affected by hCG injections and it can be used for diagnosis of pregnancy even when hCG has been given recently. SP1 also may be used as a prognostic indicator of the outcome of the pregnancy.

Serum immunoreactive beta-endorphin in the human ovulatory cycle

Daily serum immunoreactive beta-endorphin (IR-beta-EP) levels, in conjunction with luteinizing hormone, follicle-stimulating hormone, 17 beta-oestradiol, progesterone, and prolactin, were measured during the ovulatory cycle in five healthy Chinese women. Standardization of raw data by conversion to the statistical "Z scores" and composite plot of the five cycles showed that serum IR-beta-EP levels fluctuated during the follicular, late luteal, and menstrual phases. A preovulatory rise occurred two to three days prior to the luteinizing hormone surge, followed by a postovulatory dip for two to three days. The concentrations of IR-beta-EP were (mean +/- S.E.M.): 85.5 +/- 10.5 pg/mL (n = 36) in the follicular phase; 92.4 +/- 36.5 pg/mL (n = 5) in the ovulatory phase; 72.3 +/- 16.6 pg/mL (n = 7) in the early luteal phase; 100.0 +/- 10.7 pg/mL (n = 38) in the late luteal phase. The values in the luteal phase were the highest of any in the ovulatory cycle. The findings suggest that the fluctuation of endogenous beta-EP is under the influence of, among other factors, ovarian sex steroids. The significance of beta-EP in the regulation of gonadotropin release during normal menstrual cycles is discussed.

Plasma levels of immunoreactive melatonin, estradiol, progesterone, follicle stimulating hormone, and beta-human chorionic gonadotropin during pregnancy and shortly after parturition in humans

Plasma concentrations of immunoreactive melatonin, estradiol, progesterone, follicle stimulating hormone (FSH), and beta-human chorionic gonadotropin (beta hCG) were studied between 1000 and 1230 h in 105 Chinese females during six periods of normal pregnancy and 1-5 min after normal delivery. We have also examined the midday levels of immunoreactive melatonin in the cord blood of fetuses and plasma collected 1-5 min after and 24 h after delivery from their mothers. Concentrations of hormone immunoreactivities were determined by radioimmunoassay, and distinct fluctuations of all hormones were recorded during pregnancy. In the pregnant females, there were significant negative correlations between melatonin and estradiol, melatonin and progesterone, beta hCG and progesterone, and beta hCG and estradiol, and positive correlations between melatonin and FSH and progesterone and estradiol. Furthermore, plasma melatonin levels in the cord blood demonstrated no sex difference and were significantly lower than and correlated positively with the levels in their mothers. Our results suggest that sex steroids may inhibit and FSH may potentiate circulating melatonin levels in gravid women; changes in the levels of melatonin during pregnancy may affect the in utero development of the human embryo; and circulating melatonin in the mother may be the major source of blood melatonin in the fetus before parturition.

Vacuum extractor: a safe instrument?

One thousand five hundred and twenty-six records of deliveries with vacuum extractor in 1982 and 1983 in the Hong Kong University Department of Obstetrics and Gynaecology were reviewed. Vacuum extractor was found to be easy and safe to use even by inexperienced house-staff. Vacuum extractor was especially useful in the delivery of malpositioned fetal heads because of its mechanism of allowing autorotation. Its advantage of not occupying extra space in the pelvis was most beneficial to the relatively smaller Chinese pelvis. Maternal injury was uncommon. Fetal scalp injury like cephalhaematoma was not uncommon but serious scalp injury was infrequent. Perinatal mortality rate attributed to the instrument was low (0.6/1,000). However, in order to achieve safety to the mother and fetus, strict rules in application of the vacuum extractor must be observed.

Prolactin in human cervical mucus

The pattern of change in the levels of prolactin (PRL) in cervical mucus was studied in 19 normal ovulatory women. The concentration of PRL in cervical mucus was generally higher than that in plasma except at midcycle, when a reverse relationship was observed. The concentration of PRL in mucus obtained at midcycle was lower than mucus obtained during follicular phase or luteal phase. There were no significant differences in the total PRL content among preovulatory, midcycle and postovulatory cervical mucus samples. The amount of cervical mucus markedly increased during the periovulatory period (two days from the peak of plasma luteinizing hormone). The cervical mucus PRL level undergoes cyclic changes during the normal menstrual cycle, and the decrease in PRL concentration in mucus at midcycle is most likely a result of the dilutional effect of increased mucus volume. The physiological implication of the presence of PRL in human cervical mucus is also discussed.

Spermatozoal fertilizing capacity in polyzoospermia: a preliminary study

Men with the spermatological symptom of polyzoospermia (greater than 250 X 10(6) sperm/ml) have been reported to seldom impregnate their wives. It was the aim of this study to investigate the spermatozoal fertilizing capacity in polyzoospermia by the human sperm and zona-free hamster ova penetration bioassay. General semen characteristics and in vitro spermatozoal fertilizing capacity were studied in 12 polyzoospermic male partners of couples of infertile marriages. The results were compared with those from a control group of normospermic fertile men (n = 22). No significant differences in sperm motility, normal morphology and in vitro spermatozoal fertilizing capacity were found between the two groups. The polyzoospermic men we studied did not appear to have any defect with the spermatozoal fertilizing capacity, as assessed by the heterologous sperm--ova penetration bioassay. The apparent impairment of fertility and higher abortion rate in couples with polyzoospermic male partners, as described in the literature, may be related to chromosomal aberrations and/or other unknown functional defect of the spermatozoa.

Psychosocial aspects of gestational trophoblastic disease in Chinese residents of Hong Kong

Gestational trophoblastic disease has several special aspects as compared with others tumors of the female genital tract. It occurs in young women who want to start a family and expect to have a normal pregnancy. It can be very effectively treated with chemotherapeutic agents, and the subsequent reproductive potential of these young women is not affected. In a survey of 105 Chinese residents of Hong Kong who had had the disease, it was found that their emotional reactions to the disease and treatment, the effects of such on their self-esteem, martial and sexual life, and their attitudes towards their physicians and future pregnancy were different from those of their Western counterparts.

Seminal plasma beta-human chorionic gonadotropin (beta-HCG): relationships with seminal characteristics and spermatozoal fertilizing capacity

Seminal plasma beta-human chorionic gonadotropin (beta-HCG) levels were determined in 254 semen samples collected from fertile and suspected subfertile men, and their relationships with seminal characteristics and spermatozoal fertilizing capacity were evaluated. Radioimmunoassayable beta-HCG, as defined by greater than 5 mIU/ml concentration, was demonstrated in only 44.5% of all the samples studied. beta-HCG concentrations were similar in normospermic, oligospermic and azoospermic samples. There were no significant differences in beta-HCG concentration between high-motility and low-motility samples, between normal-morphology and abnormal-morphology samples, and between high-fertilizing capacity and low-fertilizing capacity samples. No significant correlations between the concentrations of beta-HCG and individual parameters of semen analysis and spermatozoal fertilizing capacity among the various groups of samples were observed. The physiological role of seminal plasma beta-HCG is presently uncertain and the relationship of its determination to male fertility requires further investigation.

The relationship between the human sperm hypoosmotic swelling test, routine semen analysis, and the human sperm zona-free hamster ovum penetration assay

The functional integrity of sperm membranes of 270 semen samples collected from fertile men and the male partners in couples with infertile marriages was assessed by the hypoosmotic swelling test and the results correlated with routine semen analysis and the human sperm zona-free hamster ovum penetration assay. Semen samples with abnormal semen parameters had lower values of percentage of swollen sperm after hypoosmotic treatment in comparison with those with normal semen parameters. A weak positive correlation was observed between sperm swelling and sperm morphologic features (r = 0.32, P less than 0.05) and between sperm swelling and sperm motility (r = 0.22, P less than 0.05). Insignificant correlation was observed between sperm swelling and in vitro sperm fertilizing capacity, as assessed by the zona-free hamster ovum penetration assay. The results indicate that the sperm swelling test and the zona-free hamster ovum penetration assay are evaluating different functional qualities of sperm that are apparently not associated with each other.

Reactions to emergency hysterectomy

The recovery from emergency hysterectomy of 18 Chinese patients is described. During the recovery period, patients experienced fear, depression, anger, doubt, selfreproach, and multiple somatic complaints without physical origins. Sexual activity was reduced. The recovery course was particularly difficult for those patients who were nonsymptomatic before operation, those who still wanted to bear more children, and those who lacked family support. These women needed continuous reassurance and ample opportunities to ventilate their feelings. None of the patients had psychiatric sequelae requiring expert consultation after the operation. It is emphasized that the reactions and needs of these patients deserve recognition, attention, and follow-up.

Comparative study of total urinary oestrogen and first morning urinary oestrogen in monitoring gonadotrophin therapy

Total 24-hour urinary oestrogen has been used extensively and proven to be reliable in monitoring gonadotrophin therapy for induction of ovulation. However, the method is time consuming for the patient and incomplete collection, as expected, is not uncommon, hence interfering with the treatment result. Oestrone-3-glucuronide in first morning urine samples has been shown to correlate well with plasma oestradiol-17 beta levels during normal menstrual cycles. A comparative study was made to examine the correlation between the levels of 24-hour urinary oestrogen and first morning urinary oestrogen in patients on gonadotrophin therapy. Creatinine levels were also determined to exclude the factor of variable excretion of oestrogen. The correlation thus found is highly significant (p less than 0.001). Hence first morning urinary oestrogen to creatinine ratios may be used to replace 24-hour urinary oestrogen in biochemical monitoring of gonadotrophin therapy.

Lack of effect of exogenous prolactin on the fertilizing capacity of human spermatozoa in vitro

The effect of exogenous prolactin (PRL) on the fertilizing capacity of human spermatozoa in vitro was evaluated by the zona-free hamster ova penetration assay. Bovine and ovine PRL, in both physiological and pharmacological concentrations, failed to increase the penetration after 5 hr of incubation in vitro. The percent motility of spermatozoa was not influenced by PRL during the incubation period. Exogenous PRL does not affect the fertilizing capacity of human spermatozoa in vitro. The role of prolactin, normally present in seminal plasma and female reproductive tract fluid, in the human spermatozoal capacitation process merits further investigation.