De novo gene synthesis by an antiviral reverse transcriptase

Bacteria defend themselves from viral infection using diverse immune systems, many of which sense and target foreign nucleic acids. Defense-associated reverse transcriptase (DRT) systems provide an intriguing counterpoint to this immune strategy by instead leveraging DNA synthesis, but the identities and functions of their DNA products remain largely unknown. Here we show that DRT2 systems execute an unprecedented immunity mechanism that involves de novo gene synthesis via rolling-circle reverse transcription of a non-coding RNA (ncRNA). Unbiased profiling of RT-associated RNA and DNA ligands in DRT2-expressing cells revealed that reverse transcription generates concatenated cDNA repeats through programmed template jumping on the ncRNA. The presence of phage then triggers second-strand cDNA synthesis, leading to the production of long double-stranded DNA. Remarkably, this DNA product is efficiently transcribed, generating messenger RNAs that encode a stop codon-less, never-ending ORF (neo) whose translation causes potent growth arrest. Phylogenetic analyses and screening of diverse DRT2 homologs further revealed broad conservation of rolling-circle reverse transcription and Neo protein function. Our work highlights an elegant expansion of genome coding potential through RNA-templated gene creation, and challenges conventional paradigms of genetic information encoded along the one-dimensional axis of genomic DNA.

Uncovering Distinct Peptide Charging Behaviors in Electrospray Ionization Mass Spectrometry Using a Large-Scale Dataset

Electrospray ionization is a powerful and prevalent technique used to ionize analytes in mass spectrometry. The distribution of charges that an analyte receives (charge state distribution, CSD) is an important consideration for interpreting mass spectra. However, due to an incomplete understanding of the ionization mechanism, the analyte properties that influence CSDs are not fully understood. Here, we employ a machine learning-based approach and analyze CSDs of hundreds of thousands of peptides. Interestingly, half of the peptides exhibit charges that differ from what one would naively expect (the number of basic sites). We find that these peptides can be classified into two regimes (undercharging and overcharging) and that these two regimes display markedly different charging characteristics. Notably, peptides in the overcharging regime show minimal dependence on basic site count, and more generally, the two regimes exhibit distinct sequence determinants. These findings highlight the rich ionization behavior of peptides and the potential of CSDs for enhancing peptide identification.

Assembly and function of the amyloid-like translational repressor Rim4 is coupled with nutrient conditions

Amyloid-like protein assemblies have been associated with toxic phenotypes because of their repetitive and stable structure. However, evidence that cells exploit these structures to control function and activity of some proteins in response to stimuli has questioned this paradigm. How amyloid-like assembly can confer emergent functions and how cells couple assembly with environmental conditions remains unclear. Here, we study Rim4, an RNA-binding protein that forms translation-repressing assemblies during yeast meiosis. We demonstrate that in its assembled and repressive state, Rim4 binds RNA more efficiently than in its monomeric and idle state, revealing a causal connection between assembly and function. The Rim4-binding site location within the transcript dictates whether the assemblies can repress translation, underscoring the importance of the architecture of this RNA-protein structure for function. Rim4 assembly depends exclusively on its intrinsically disordered region and is prevented by the Ras/protein kinase A signaling pathway, which promotes growth and suppresses meiotic entry in yeast. Our results suggest a mechanism whereby cells couple a functional protein assembly with a stimulus to enforce a cell fate decision.

A high-throughput approach reveals distinct peptide charging behaviors in electrospray ionization mass spectrometry

Electrospray ionization is a powerful and prevalent technique used to ionize analytes in mass spectrometry. The distribution of charges that an analyte receives (charge state distribution, CSD) is an important consideration for interpreting mass spectra. However, due to an incomplete understanding of the ionization mechanism, the analyte properties that influence CSDs are not fully understood. Here, we employ a machine learning-based high-throughput approach and analyze CSDs of hundreds of thousands of peptides. Interestingly, half of the peptides exhibit charges that differ from what one would naively expect (number of basic sites). We find that these peptides can be classified into two regimes-undercharging and overcharging-and that these two regimes display markedly different charging characteristics. Strikingly, peptides in the overcharging regime show minimal dependence on basic site count, and more generally, the two regimes exhibit distinct sequence determinants. These findings highlight the rich ionization behavior of peptides and the potential of CSDs for enhancing peptide identification.

Mapping the chemical space of active-site targeted covalent ligands for protein tyrosine phosphatases

Protein tyrosine phosphatases (PTPs) are an important class of enzymes that modulate essential cellular processes through protein dephosphorylation and are dysregulated in various disease states. There is demand for new compounds that target the active sites of these enzymes, for use as chemical tools to dissect their biological roles or as leads for the development of new therapeutics. In this study, we explore an array of electrophiles and fragment scaffolds to investigate the required chemical parameters for covalent inhibition of tyrosine phosphatases. Our analysis juxtaposes the intrinsic electrophilicity of these compounds with their potency against several classical PTPs, revealing chemotypes that inhibit tyrosine phosphatases while minimizing excessive, potentially non-specific reactivity. We also assess sequence divergence at key residues in PTPs to explain their differential susceptibility to covalent inhibition. We anticipate that our study will inspire new strategies to develop covalent probes and inhibitors for tyrosine phosphatases.

Alternative polyadenylation alters protein dosage by switching between intronic and 3'UTR sites

Alternative polyadenylation (APA) creates distinct transcripts from the same gene by cleaving the pre-mRNA at poly(A) sites that can lie within the 3' untranslated region (3'UTR), introns, or exons. Most studies focus on APA within the 3'UTR; however, here, we show that CPSF6 insufficiency alters protein levels and causes a developmental syndrome by deregulating APA throughout the transcript. In neonatal humans and zebrafish larvae, CPSF6 insufficiency shifts poly(A) site usage between the 3'UTR and internal sites in a pathway-specific manner. Genes associated with neuronal function undergo mostly intronic APA, reducing their expression, while genes associated with heart and skeletal function mostly undergo 3'UTR APA and are up-regulated. This suggests that, under healthy conditions, cells toggle between internal and 3'UTR APA to modulate protein expression.

SEC-TMT facilitates quantitative differential analysis of protein interaction networks

The majority of cellular proteins interact with at least one partner or assemble into molecular-complexes to exert their function. This network of protein-protein interactions (PPIs) and the composition of macromolecular machines differ between cell types and physiological conditions. Therefore, characterizing PPI networks and their dynamic changes is vital for discovering novel biological functions and underlying mechanisms of cellular processes. However, producing an in-depth, global snapshot of PPIs from a given specimen requires measuring tens to thousands of LC-MS/MS runs. Consequently, while recent works made seminal contributions by mapping PPIs at great depth, almost all focused on just 1-2 conditions, generating comprehensive but mostly static PPI networks. In this study we report the development of SEC-TMT, a method that enables identifying and measuring PPIs in a quantitative manner from only 4-8 LC-MS/MS runs per biological sample. This was accomplished by incorporating tandem mass tag (TMT) multiplexing with a size exclusion chromatography mass spectrometry (SEC-MS) work-flow. SEC-TMT reduces measurement time by an order of magnitude while maintaining resolution and coverage of thousands of cellular interactions, equivalent to the gold standard in the field. We show that SEC-TMT provides benefits for conducting differential analyses to measure changes in the PPI network between conditions. This development makes it feasible to study dynamic systems at scale and holds the potential to drive more rapid discoveries of PPI impact on cellular processes.

Proteogenomic Landscape of Breast Cancer Tumorigenesis and Targeted Therapy

The integration of mass spectrometry-based proteomics with next-generation DNA and RNA sequencing profiles tumors more comprehensively. Here this "proteogenomics" approach was applied to 122 treatment-naive primary breast cancers accrued to preserve post-translational modifications, including protein phosphorylation and acetylation. Proteogenomics challenged standard breast cancer diagnoses, provided detailed analysis of the ERBB2 amplicon, defined tumor subsets that could benefit from immune checkpoint therapy, and allowed more accurate assessment of Rb status for prediction of CDK4/6 inhibitor responsiveness. Phosphoproteomics profiles uncovered novel associations between tumor suppressor loss and targetable kinases. Acetylproteome analysis highlighted acetylation on key nuclear proteins involved in the DNA damage response and revealed cross-talk between cytoplasmic and mitochondrial acetylation and metabolism. Our results underscore the potential of proteogenomics for clinical investigation of breast cancer through more accurate annotation of targetable pathways and biological features of this remarkably heterogeneous malignancy.

Proteogenomic Characterization Reveals Therapeutic Vulnerabilities in Lung Adenocarcinoma

To explore the biology of lung adenocarcinoma (LUAD) and identify new therapeutic opportunities, we performed comprehensive proteogenomic characterization of 110 tumors and 101 matched normal adjacent tissues (NATs) incorporating genomics, epigenomics, deep-scale proteomics, phosphoproteomics, and acetylproteomics. Multi-omics clustering revealed four subgroups defined by key driver mutations, country, and gender. Proteomic and phosphoproteomic data illuminated biology downstream of copy number aberrations, somatic mutations, and fusions and identified therapeutic vulnerabilities associated with driver events involving KRAS, EGFR, and ALK. Immune subtyping revealed a complex landscape, reinforced the association of STK11 with immune-cold behavior, and underscored a potential immunosuppressive role of neutrophil degranulation. Smoking-associated LUADs showed correlation with other environmental exposure signatures and a field effect in NATs. Matched NATs allowed identification of differentially expressed proteins with potential diagnostic and therapeutic utility. This proteogenomics dataset represents a unique public resource for researchers and clinicians seeking to better understand and treat lung adenocarcinomas.

Proteomics, Post-translational Modifications, and Integrative Analyses Reveal Molecular Heterogeneity within Medulloblastoma Subgroups

There is a pressing need to identify therapeutic targets in tumors with low mutation rates such as the malignant pediatric brain tumor medulloblastoma. To address this challenge, we quantitatively profiled global proteomes and phospho-proteomes of 45 medulloblastoma samples. Integrated analyses revealed that tumors with similar RNA expression vary extensively at the post-transcriptional and post-translational levels. We identified distinct pathways associated with two subsets of SHH tumors, and found post-translational modifications of MYC that are associated with poor outcomes in group 3 tumors. We found kinases associated with subtypes and showed that inhibiting PRKDC sensitizes MYC-driven cells to radiation. Our study shows that proteomics enables a more comprehensive, functional readout, providing a foundation for future therapeutic strategies.

Molecular differentiation and diversity of Forcipomyia taiwana (Diptera: Ceratopogonidae) based on the mitochondrial cytochrome oxidase II sequence

Forcipomyia taiwana (Shiraki), a biting midge, is one of the most annoying blood-sucking pests in Taiwan. In this study, partial DNA sequences of cytochrome c oxidase II from 113 individuals collected from 11 locations around the island were analyzed to delineate the differentiation pattern and possible dispersal processes of F. taiwana in Taiwan. The uncorrected nucleotide divergences, composed of mostly transition substitutions, were high (up to 2.7%) among the samples. Average comparable variations (approximately equal to 0.7%) were found within and between populations. Phylogenetic analysis suggested that several distinct lineages exist and some can be found simultaneously in some populations. A relationship between sequence divergences among populations and their relative geographical distances was observed. Moreover, haplotype diversity was high in all populations, and low to middle levels (Fst = 0.004-0.288) of genetic differentiation were found among populations. Linearized calibration from sequence divergences and phylogenetic analysis showed that different ancestral lineages of F. taiwana possibly emerged as early as 0.6 million years ago. Taken together, genetic exchanges among these divergently ancestral lineages, likely caused by recent artificial events, have possibly led to the similarly diversified compositions of F. taiwana populations all around Taiwan nowadays.

Universal screening of human immunodeficiency virus infection in pregnant women in Hong Kong: prospective study

OBJECTIVE

To evaluate universal screening with an opt-out approach of pregnant women for human immunodeficiency virus infection.

DESIGN

Prospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

All women booked or delivered in Kwong Wah Hospital from 1 January 1999 to 30 November 1999 were recruited.

MAIN OUTCOME MEASURES

Numbers of women who received the human immunodeficiency virus antibody screening test, refused the test (and the reasons why), tested positive, and tested positive with confirmation by immunoblot study.

RESULTS

A total of 5597 women were recruited and 5459 screening tests performed in this study. Of the 16 screened positive cases, three were confirmed by immunoblot study. The overall acceptance rate for the test was 97.5%. The acceptance rate among the 5191 women recruited through the hospital's booking clinic was not significantly different from that among the 406 women who did not go through the hospital's booking clinic (97.6% versus 96.6%).

CONCLUSION

Universal screening of pregnant women for human immunodeficiency virus infection with an opt-out approach is practical, feasible, and clinically acceptable in Hong Kong.

Findings in women with postmenopausal bleeding investigated with hysteroscopy

Most reports on histopathological findings of postmenopausal bleeding were published before hysteroscopy was widely used. Recent studies have shown that hysteroscopic examination is better than dilatation and curettage alone in detecting intrauterine pathology. The aim of this study is to assess histopathological findings of patients presented with postmenopausal bleeding after incorporation of hysteroscopic examination. Between 1 January 1996 and 31 December 1996, a total of 199 consecutive patients presenting with postmenopausal bleeding to a regional hospital were reviewed. Patients were investigated with cervical biopsy, endometrial aspiration or hysteroscopy and curettage. Excluding patients who had hysterectomy and cervical cancer, 97% of the patients had hysteroscopic examination. The majority of patients with postmenopausal bleeding had atrophic vaginitis and/or atrophic endometrium (58.8%). Other common diagnoses were endometrial polyp (9.4%), endometrial carcinoma (9.4%) and carcinoma of the cervix (6%). Other diagnoses included submucous fibroid, endometrial hyperplasia, pyometra, ovarian cancer and urethral caruncle. Pathologies found were similar to early reports, except that incidences of submucous fibroids and endometrial polyps were higher (13.4%). We concluded that all patients with postmenopausal bleeding should be investigated thoroughly as 22% have significant pathology. Hysteroscopy is the preferred investigation because of high incidences of endometrial polyps and submucous fibroids.

A multicentre randomized controlled trial of oral misoprostol and i.m. syntometrine in the management of the third stage of labour

Postpartum haemorrhage accounts for nearly 28% of maternal mortality in developing countries. Syntometrine is an effective and commonly used oxytocic in preventing postpartum haemorrhage, but it requires a controlled storage environment and i.m. administration. Misoprostol is an orally active uterotonic agent. A total of 2058 patients having a singleton pregnancy, low risk for postpartum haemorrhage and vaginal delivery were randomized to receive either 1 ml syntometrine or 600 microgram misoprostol for the management of the third stage of labour. There were no significant differences between the two groups in the mean blood loss, the incidence of postpartum haemorrhage and the fall in haemoglobin concentration. The need for additional oxytocic injection was significantly higher in the misoprostol group [relative risk (RR) 1.62, 95% confidence interval (CI) 1.34-1.96], but that of manual removal of placenta was reduced (RR 0.29, 95% CI 0.09-0.87). Shivering and transient pyrexia were more common in the misoprostol group. Oral misoprostol might be used in the management of the third stage, especially in situations where the use of syntometrine is contraindicated and facilities for storage and parenteral administration of oxytocics are limited.

Pilot study on the use of repeated doses of misoprostol in termination of pregnancy at less than 9 weeks of gestation

Pregnancy was terminated by repeated doses of vaginal misoprostol in 20 women at a gestational age of less than 9 weeks. The women were given 800 microg of vaginal misoprostol as an initial dose followed by 400 microg of vaginal misoprostol every 3 h for 4 doses. Fourteen women (70%, 95% confidence interval: 48 85%) had a complete abortion. Two women (10%) had a missed abortion, and two (10%) had an ongoing pregnancy. Two women ( 10%) had an incomplete abortion. The interval between the first dose of misoprostol and the passage of tissue mass was 25.3 +/- 34.4 h (median: 15 h). The duration of vaginal bleeding was 23.6 +/- 20.4 days (median: 14 days). Side-effects were mild and there was no significant drop in hemoglobin level. Repeated doses of vaginal misoprostol may be an alternative for women who do not want surgical abortion and who live in an area where mifepristone is not available.

Single foetal death in twin pregnancies: review of the maternal and neonatal outcomes and management

OBJECTIVE

To review the maternal and neonatal outcomes, and management of single foetal death in twin pregnancies.

DATA SOURCES

Medline literature search (1950 to 1999) and hospital audit of single antepartum foetal deaths in twin pregnancy from 1993 through 1997.

DATA SELECTION

Key words for literature search: twin pregnancy/pregnancies; single fetal death/demise.

DATA EXTRACTION

Data were extracted and reviewed independently by the authors.

DATA SYNTHESIS

During the study period, 182 (0.76%) of 23,804 deliveries involved twin pregnancies. Seven (3.8%) of the twin pregnancies were complicated by the death of one foetus. Single foetal death in a twin pregnancy in the late second and third trimesters is associated with significant morbidity and mortality in the surviving co-twin, especially in a pregnancy involving monochorionic twins. Management should be individualised; conservative management is preferred by most obstetricians.

CONCLUSION

Single foetal death in twin pregnancies should be managed in a tertiary referral centre, where intensive foetal surveillance and adequate neonatal support are available. A multidisciplinary approach should be adopted.

Ten years' experience of antenatal mean corpuscular volume screening and prenatal diagnosis for thalassaemias in Hong Kong

OBJECTIVE

To determine the prevalence of thalassaemia carriers in Hong Kong.

SUBJECTS AND METHODS

From 1988 to 1997, 25,834 (53.7%) of 48,089 mothers were screened for thalassaemias by mean corpuscular volume (MCV) at the first antenatal visit.

RESULTS

In the screened population of 25,834, 2229 (8.6%) had MCV < or = 75 fl. Of these, 1121 (4.3%) were alpha-thal, 715 (2.8%) were beta-thal, 23 (0.1%) were alpha beta-thal, 57 (0.2%) were other haemoglobin variants, and 281 (1.1%) had either iron deficiency or uncertain causes. Out of 200 pregnancies at risk for homozygous alpha-thal-1 and 32 at risk for beta-thal major, 27 homozygous alpha-thal-1 and 7 beta-thal major were identified, compared favourably with the expected figures of 23 and 9.

CONCLUSION

Antenatal screening for thalassaemias by MCV is simple, effective and reliable. Universal screening has a different impact as bone marrow or cord blood stem cell transplant provides cure for beta-thal major. At risk couples have, as an alternative to termination of pregnancy, the option of early detection and treatment for their affected newborns or fetuses.

Stepwise pain score analysis of the effect of local lignocaine on outpatient hysteroscopy: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To assess the efficacy of lignocaine gel in reducing the overall pain and pain of individual steps during outpatient hysteroscopy in comparison with placebo (no anesthesia).

DESIGN

A prospective, randomized, double-blind, placebo-controlled trial.

SETTING

Outpatient hysteroscopy clinic in a regional hospital in Hong Kong.

PATIENT(S)

A total of 500 Chinese patients undergoing outpatient hysteroscopy.

INTERVENTION(S)

Application of lignocaine gel to the cervix during outpatient hysteroscopy.

MAIN OUTCOME MEASURE(S)

Mean pain score using present pain intensity, overall pain score measured by total area under the curve, and the pain score of individual steps in the procedure in patients receiving lignocaine gel were compared with those of patients having no anesthesia. The failure rate and poor-view rate in both groups were also compared.

RESULT(S)

There were no statistically significant differences in mean pain score, overall pain score, and pain score of individual steps between the lignocaine group and controls. The failure rate and poor-view rate also showed no statistically significant differences.

CONCLUSION(S)

Outpatient hysteroscopy without anesthesia is acceptable to most Chinese women, and the local application of lignocaine gel is not effective in reducing pain.

A comparison of two regimens of intravaginal misoprostol for termination of second trimester pregnancy: a randomized comparative trial

A prospective randomized trial was conducted in 148 women to compare the efficacy of two regimens of vaginal misoprostol for termination of second trimester pregnancy. Women aged 16-40 years requesting termination of second trimester pregnancy were randomized into two groups. Women in group 1 were given vaginal misoprostol 400 microg every 3 h for a maximum of five doses in 24 h. Women in group 2 were given vaginal misoprostol 400 microg every 6 h for a maximum of three doses in 24 h. If women did not abort in 24 h, the same regimen was repeated. The median induction-abortion interval in group 1 (15.2 h) was significantly shorter (P < 0.01) than that in the group 2 (19.0 h). The percentage of women who achieved successful abortion within 48 h in group 1 (90.5%) was also significantly higher (P < 0.02) than that in group 2 (75.7%). The incidence of fever was more common in group 1 (P = 0.01). It is concluded that the regimen of vaginal misoprostol 400 microg every 3 h with maximum of five doses in 24 h was more effective than the regimen of misoprostol every 6 h in termination of second trimester pregnancy.

Vaginal misoprostol compared with vaginal gemeprost in termination of second trimester pregnancy. A randomized trial

A prospective randomized trial was conducted in 140 women to compare the efficacy of vaginal gemeprost with vaginal misoprostol for termination of second trimester pregnancy. Women requesting termination of second trimester pregnancy were randomized into two groups. Group A women were given 1 mg vaginal gemeprost every 3 h for a maximum of five doses in the first 24 h, whereas group B women were given 400 micrograms vaginal misoprostol every 3 h for a maximum of five doses in 24 h. The median induction-abortion interval in the vaginal misoprostol group (14.1 h) was significantly shorter than that in the gemeprost group (19.5 h). The percentage of women who achieved successful abortion within 24 h in the misoprostol group (80.0%) was significantly higher than that in the gemeprost group (58.6%). There was no significant difference in the incidence of side effects between the two groups except for diarrhea, which was more common in the gemeprost group. The incidence of fever was more common in the misoprostol group. It is concluded that vaginal misoprostol is more effective than gemeprost in termination of second trimester pregnancy.

Outpatient diagnostic hysteroscopy: analysis of 429 cases

OBJECTIVE

To evaluate the diagnostic accuracy of outpatient hysteroscopy.

METHODS

Outpatient CO2 hysteroscopy using video-camera for monitoring was performed on 429 patients from November 1995 to December 1996. The indications included post-menopausal bleeding (32.2%), menorrhagia (25.4%), irregular bleeding (24.7%), intermenstrual spotting (10.2%) and others (7.5%).

RESULTS

Hysteroscopy was successfully performed on 420 (97.9%) patients. Although no anaesthetics were used, only two (0.47%) patients complained of severe pain during the procedure. Twenty-one (4.9%) patients had poor view due to submucosal fibroid or bloody view. There were no operative complications. Normal uterine cavity was found in 36.8% and atrophic endometrium in 34.7% of patients. The pathologies included submucosal fibroid (10.7%), endometrial polyp (5.8%) and fibroid polyp (2.8%). Five (1.2%) out of 429 patients were confirmed histologically to have endometrial carcinoma. No malignant lesions were missed. A total of 372 (86.7%) patients had histological confirmation of hysteroscopic findings. In 57 (13.2%) patients, the histological results did not correlate with the hysteroscopic findings.

CONCLUSIONS

Outpatient hysteroscopy and suction curettage is a safe, cost-effective and acceptable procedure.

The accuracy of intraoperative frozen section in the diagnosis of ovarian tumors

A retrospective study of 316 ovarian neoplasms which had frozen section evaluation between January 1, 1990 to December 31, 1995 was conducted to determine the accuracy of frozen section diagnosis of ovarian neoplasms. The frozen section results were compared with final diagnoses from paraffin sections. The frozen section diagnosis was accurate in 95.2% of all cases and inaccurate in 4.8%. The positive predictive value of a positive (or malignant) frozen section was 100%, the negative predictive value of a negative (or benign) frozen section was 98.2%. The sensitivity for malignant tumors as 87%. For tumors of borderline malignancy, the sensitivity and specificity were 60% and 98.6% respectively. Of the false negative frozen section diagnoses, 73% (8 cases) occurred in tumors of borderline malignancy. We concluded that with the exception of the sensitivity for the diagnosis of tumors of borderline malignancy, the sensitivity and specificity of frozen section diagnosis for benign and overtly malignant ovarian neoplasms are high.

Second-trimester maternal serum alpha-fetoprotein and human chorionic gonadotrophin screening for Down's syndrome in Hong Kong

Second-trimester maternal serum screening for fetal Down's syndrome is well established in many Western countries. Its usefulness and acceptability is unknown in the Asian countries. Between June 1994 and December 1996, we offered second-trimester serum AFP and hCG screening to pregnant women in Hong Kong who were less than 35 years old and without other risk factors for chromosome abnormalities. Each woman was assigned a risk of having a Down's syndrome term pregnancy by using a computer software program that took into account her age. weight, AFP and hCG MOMs. All those with a risk of one in 250 or greater were designated screen-positive, subject to the revision of gestation by ultrasound examination. 9,177 women with singleton pregnancies (93 per cent were Chinese) were screened. The uptake of screening was 75 per cent. 281 women (three per cent) were initially classified to be screen-positive. After revision of the gestation by ultrasound examination, 183 women (two per cent) were 'true' screen-positive and 164 (90 per cent) accepted the offer of amniocentesis. Eight of these pregnancies were affected by Down's syndrome and all the women elected pregnancy termination. The odds of being affected, given a positive screening result, were one in 23. Six Down's syndrome pregnancies were missed by screening programme. The detection rate was 57 per cent. The study showed that second-trimester serum screening for fetal Down's syndrome was feasible and accepted in the Hong Kong population.

Critical care in obstetrical patients: an eight-year review

OBJECTIVE

To review the clinical characteristics and outcomes of critically ill obstetrical patients and to determine the outcome predictability using the Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system.

METHODS

A retrospective data collection of all obstetrical patients (n = 49) admitted for more than 24 hours to the Intensive Care Unit at Kwong Wah Hospital from 1988 to 1995 was conducted. Demographics, obstetric data, preexistent medical problems, diagnosis, days staying in the ICU and ICU related data were recorded for each patient.

RESULTS

Obstetric admissions to ICU during the study period represented 0.12% of all deliveries during this period. There was a predominance of postpartum admissions and obstetric diagnosis responsible for the patients' critical illness. Massive postpartum haemorrhage was the single most common cause of ICU admission, representing 53.0% of all patients. Preeclampsia and eclampsia (14.3%), anaesthesia related complications (14.3%), and medical diseases complicating pregnancy (14.3%) were the other common disease categories for ICU admission. Two cases (4.1%) of surgical disease complicating pregnancy were admitted. The maternal mortality rate was 5.1 deaths per 100,000 total births, or 2 maternal deaths in 39,354 total deliveries in this study period. All deaths were due to nonobstetric causes. The perinatal mortality rate was 10.0% (5 cases) in this study group.

CONCLUSIONS

When applying the Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system in predicting the final outcome in this group of obstetric patients, we found that our obstetric patients requiring intensive care had a better outcome than predicted, as expressed by a low mortality ratio (0.25).

Second-trimester maternal urinary gonadotrophin peptide screening for fetal Down syndrome in Asian women

Maternal urinary gonadotrophin peptide (UGP) was recently found to be elevated in second-trimester Down syndrome pregnancies. There is controversy about its screening efficacy. Data in the Asian population are scanty. We measured the UGP levels in 29 Down syndrome pregnancies and 297 controls and expressed them as a ratio of the urine creatinine concentration. Median UGP MOM was elevated to 3.44 (95 per cent confidence interval 1.99-5.13) in cases, compared with controls. UGP values were widely scattered in cases and controls with extensive overlap such that only 35 per cent of Down syndrome cases were expected to be detected at a 5 per cent false-positive rate. The data of the present study and previous reports show that there is a wide variability of gestation-specific UGP median values. UGP alone does not appear to be an effective screening marker for fetal Down syndrome.

Conservative management of patients with histological incomplete excision of cervical intraepithelial neoplasia after large loop excision of transformation zone

OBJECTIVE

To evaluate conservative management of patients with histological incomplete excision of CIN after large loop excision of transformation zone (LLETZ).

METHODS

Two hundred and seventeen patients with high grade CIN were treated with LLETZ from October 1, 1992 to December 31, 1994. Fifty-three patients (24.4%) had incomplete excision on histology. All patients were followed up cytologically every 3 to 6 months during the first 18 months and then yearly till December 1996. Those patients with positive endocervical margins were followed up with both cervical smear and endocervical smear.

RESULTS

The mean follow-up duration was 30.4 months. Ten patients were found to have persistent or recurrent disease. Five patients had second LLETZ and complete excision was achieved in 4 of them, one patient had cone biopsy and two had hysterectomy. One patient was found to have stage I a cervical cancer.

CONCLUSION

A report of incomplete excision of CIN after LLETZ calls for follow-up with cytology and colposcopy and not aggressive retreatment.

Termination of second trimester pregnancy with gemeprost and misoprostol: a randomized double-blind placebo-controlled trial

A prospective randomized double-blind placebo-controlled trial was conducted in 70 subjects to determine whether pre-treatment with misoprostol could facilitate termination of second trimester pregnancy by gemeprost. The women received either 400 micrograms oral misoprostol or placebo tablets 12 hours before the administration of vaginal pessary of gemeprost 1 mg every 3 hours. There were no significant differences in induction-abortion interval and the amount of gemeprost required between the misoprostol and the placebo group. There was no significant difference in the incidence of side effects or analgesic requirement between the two groups. We conclude that oral misoprostol is not useful in facilitating termination of second trimester pregnancy by gemeprost.

Linking phospholipase A2 to phospholipid turnover and prostaglandin synthesis in mast cell granules

Rapid incorporation of exogenous arachidonic acid into phospholipid has been detected in conjunction with eicosanoid synthesis by purified mast cell granules [Chock, S. P. & Schmauder-Chock, E. A. (1988) Biochem. Biophys. Res. Commun. 156, 1308-1315]. The species of phospholipid formed has now been identified primarily as phosphatidylinositol. A calcium-dependent phospholipase A2 has also been detected in the secretory granule. This enzyme, like the cyclooxygenase [Schmauder-Chock, E. A. & Chock, S. P. (1989) J. Histochem. Cytochem. 37, 1319-1328], appears to bind tightly to the granule matrix components. It is heat resistant and requires millimolar concentrations of calcium for optimal activity. It prefers phosphatidylinositol over phosphatidylcholine as substrate. Since the granule contains a large amount of phospholipid, the action of this phospholipase A2 can provide the required substrate for the arachidonic acid cascade. These findings provide the basis for linking phospholipase A2 to the production of eicosanoids during granule exocytosis. Since the granule also contains both an active acylating system that can rapidly reacylate lysophosphatidylinositol to form phosphatidylinositol, and an active phospholipase A2 which hydrolyzes phosphatidylinositol, a rapid turnover involving the fatty acid at the sn-2 position of phosphatidylinositol may occur. These findings are consistent with our postulation that the secretory granule is the source and/or the cause of many of the early biochemical events associated with the process of stimulus-secretion coupling.

Human erythrocyte as a model for investigating muscarinic agonists and antagonists

1. Human erythrocyte muscarinic receptor is further classified as M1 subtype by its binding of [3H]pirenzepine (a specific M1 antagonist). Conversely, binding of [3H]piperidinyl AF-DX116 (a specific M2 antagonist) is not detected. 2. There are high correlations between the binding efficacies of 25 known or putative cholinergic agents using either human erythrocyte membrane or mouse caudate homogenate. Also the in vitro data corresponds satisfactorily with in vivo data measuring the protective effect of these compounds against organophosphate poisoning. 3. The human erythrocyte membrane is an efficient model for investigating cholinergic agonists and antagonists.

The modulation of dopamine-sensitive adenylate cyclase activity in the mouse caudate nucleus by estradiol

When levodopa (L-DOPA) is administered to mice, the central nervous system responses to the dopamine stimulation were less sensitive in female than in the male mice. The sensitivity is reflected both behaviorally and biochemically. The behavioral response were measured by scores recorded after intraperitoneal injection of a standard dose of L-DOPA. The biochemical studies included the determination of the cyclic AMP produced by in vitro experiments after incubating dopamine with mouse caudate nucleus homogenates. This insensitivity to dopamine stimulation in female animals can be reversed by ovariectomy. Estradiol treatment in vivo suppressed the dopamine stimulation, while estradiol directly added to the caudate nucleus homogenate does not affect the dopamine-sensitive adenylate cyclase activity. These findings indicate that the estradiol-induced effects on the brain enzyme are indirect. The female sex hormone does have an effect on the central dopaminergic system. However, the underlying mechanism(s) cannot be delineated by the present studies.

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.

Rudimentary uterine horn with adenomyosis and pelvic endometriosis in a 23-year-old girl

A case of rudimentary uterine horn with adenomyosis and pelvic endometriosis in a 23-year-old girl is presented. The association of endometriosis and uterine anomalies is discussed. The difficulty in the management of adenomyosis in adolescence is stressed.

Thymectomy in myasthenia gravis during pregnancy

A 24 year old woman with myasthenia gravis suffered an antepartum exacerbation which failed to respond to increasing dosages of pyridostigmine. Thymectomy performed in the second trimester was followed by clinical improvement and full term vaginal delivery with no puerperal deterioration.

Seminal plasma transferrin and seminiferous tubular dysfunction

Seminal plasma transferrin levels were assayed in 158 random semen samples collected from normospermic, oligospermic, and azoospermic men, and their relationships with seminal characteristics, sperm fertilizing capacity as assessed by the zona-free hamster ova penetration assay, and serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were evaluated. The concentrations of seminal plasma transferrin in azoospermic, oligospermic and postvasectomy samples were significantly lower than those in normospermic samples. Seminal plasma transferrin concentrations were similar in azoospermia due to obstruction of the reproductive tract or damage to the germinal epithelium. No significant difference in seminal plasma transferrin concentrations was observed in the groups of subjects with normal and elevated FSH or normal and elevated LH. A positive correlation was observed between seminal plasma transferrin concentration and sperm density and between total semen transferrin content and the total number of sperm in the ejaculate. There were no significant correlations between seminal plasma transferrin concentration and sperm motility, percent normal sperm, sperm fertilizing capacity, and serum FSH or LH concentration. The results indicate that seminal plasma transferrin is not a useful marker for Sertoli cell or seminiferous tubular dysfunction. In addition, it is doubtful that measurement of seminal plasma transferrin will yield additional information regarding the fertility potential of semen samples.

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.

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.

Identification and characterization of human erythrocyte muscarinic receptors

Cholinergic muscarinic but not nicotinic receptors could be detected on the outer surface of the human red blood cell membrane by direct labelled ligand binding. This 3H-QNB binding could be inhibited by atropine. The erythrocyte cholinergic receptor was similar to brain muscarinic receptor in regard to stimulation of cGMP production.

Postmenopausal tuberculous cervicitis

A patient with tuberculosis of the cervix who presented with postmenopausal bleeding is reported and the literature is reviewed.

Aetiological factors in the genesis of pregnancy hydronephrosis

In order to identify possible aetiological factors in the genesis of physiological hydronephrosis in pregnancy, the degree of pelvic-calyceal dilatation in 90 asymptomatic pregnant women was correlated with levels of plasma oestradiol, progesterone, 24-hour urinary oestriol, the site of the placenta, birthweight of the fetus, and pelvic inlet measurements. A grading system based on maximum calyceal diameter was used; 90% of the patients were found to have at least mild dilatation on the right side. No correlation was demonstrated between the degree of hydronephrosis and the levels of oestradiol, progesterone and 24-hour urinary oestriol excretion. The birth-weight of the fetus and its relationship with the pelvic inlet measurements also did not correlate with the occurrence of hydronephrotic changes in the kidneys. The only significant positive finding was a higher incidence of moderate and severe hydronephrosis occurring in patients with a right-sided placenta than compared with the left (x2 = 4.77; p less than 0.05), although the sensitivity and specificity in predicting hydronephrosis from a right-sided placenta is low (53% and 66% respectively). Our results support the hypothesis of a mechanical aetiology in the genesis of pregnancy hydronephrosis, where vascular compression on the ureters may be an important contributory factor. Our study has also shown that urinary tract infection and reduction of creatinine clearance were not more common in patients with moderate or severe pelvic-calyceal dilatation.

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.

Dextropreponderance of corpus luteum rupture. A clinical study

A retrospective study of 55 consecutive patients with cystic corpora lutea, corpus luteum cysts or hematomas was undertaken to verify the observation of a right-side predominance in the incidence of rupture. Thirty-nine patients had a ruptured corpus luteum diagnosed surgically and confirmed histologically. No difference was observed in the overall distribution, the volume of hemorrhage or the size of the cysts between the two sides. A statistically significantly higher incidence of rupture was found on the right side (81.25%) as compared to the left (56.52%). We propose a working hypothesis of a difference in the ovarian venous architecture that causes a higher intraluminal pressure in the right corpus luteum and the dextropreponderance of ruptures.

Cross-sectional study of semen parameters in a large group of normal Chinese men

Testicular size, semen characteristics and serum reproductive hormone levels were studied in 1239 normal Chinese men. The mean testicular size of 17 ml in this group of subjects was similar to other reports in Orientals but was smaller than that reported in Caucasians. Semen volume, and the sperm count, motility and morphology were comparable to those described for Caucasian subjects. The cervical mucus penetration test (Kremer's test) and the zona-free hamster egg penetration test were also studied in some of the subjects. Age showed a positive correlation with the serum levels of FSH and LH, which were highly correlated with each other. Sperm concentration and the total sperm count were positively correlated with testicular volume, the length of abstinence, the % of sperm with an oval head, and the zona-free hamster egg penetration test, but were negatively correlated with serum FSH. Sperm motility was negatively correlated with the duration of abstinence but was positively correlated with the % normal sperm. The results constitute a normal data base from Chinese men for comparison with studies in male infertility and fertility regulation.