Quality control of mRNA 3'-end processing is linked to the nuclear exosome

An emerging theme in messenger RNA metabolism is the coupling of nuclear pre-mRNA processing events, which contributes to mRNA quality control. Most eukaryotic mRNAs acquire a poly(A) tail during 3'-end processing within the nucleus, and this is coupled to efficient export of mRNAs to the cytoplasm. In the yeast Saccharomyces cerevisiae, a common consequence of defective nuclear export of mRNA is the hyperadenylation of nascent transcripts, which are sequestered at or near their sites of transcription. This implies that polyadenylation and nuclear export are coupled in a step that involves the release of mRNA from transcription site foci. Here we demonstrate that transcripts which fail to acquire a poly(A) tail are also retained at or near transcription sites. Surprisingly, this retention mechanism requires the protein Rrp6p and the nuclear exosome, a large complex of exonucleolytic enzymes. In exosome mutants, hypo- as well as hyperadenylated mRNAs are released and translated. These observations suggest that the exosome contributes to a checkpoint that monitors proper 3'-end formation of mRNA.

Irish orthopaedic patients' attitudes to blood transfusion

This study was designed in response to perceived increased public anxiety about the risks of allogenic blood transfusion. A questionnaire was completed by 203 patients attending an elective orthopaedic hospital. The questionnaire examined patients' factual knowledge about various aspects of transfusion, their attitudes to blood transfusion and confidence in the safety of blood products. Despite recent publicity, only 124 patients (61%) regarded blood transfusion as a risk for hepatitis transmission while 172 patients (85%) knew of the risk of blood transmission of HIV. 22 patients (11%) reported that they would have no concerns about receiving a blood transfusion, while at the other extreme, 9 (5%) would not be willing to receive blood under any circumstances. 162 patients (80%) felt that allogenic blood transfusion was either entirely safe or that there was an acceptable small risk associated with it. A majority of responders (109 patients, 54%) reported they would favour autologous transfusion if available. Current practices and alternatives to traditional allogenic blood transfusion are discussed in the context of elective orthopaedic surgery.

A block to mRNA nuclear export in S. cerevisiae leads to hyperadenylation of transcripts that accumulate at the site of transcription

Several factors contribute to nuclear mRNA export in Saccharomyces cerevisiae, including Mex67p, Mtr2p, Gle1p, Nup159p, Dbp5p, and Rip1p. Strains carrying mutations in these factors show rapid and dramatic nuclear accumulation of poly(A)(+) RNA. We have characterized two heat shock mRNAs, SSA4 and HSP104, in these mutant backgrounds; each transcript concentrates in a single intranuclear focus. Evidence suggests that it coincides with the site of transcription. Interestingly, all detectable SSA4 transcripts have undergone 3'-end formation, indicating that RNAs in the foci are no longer nascent. Poly(A) tails of the transcripts are also dramatically longer in all of these export mutants. Based on all of the data, we suggest that very early mRNA maturation events determine transcript export competence.

Guidelines for molecular genetic detection of susceptibility to malignant hyperthermia

Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic disease triggered by several anaesthetic agents. The in vitro muscle contracture test (IVCT) is the standard test to establish an individual's risk of susceptibility to MH. Clinical practitioners and geneticists of the European MH Group have agreed on the present guidelines for the detection of MH susceptibility using molecular genetic techniques and/or IVCT to predict the risk of MH.

West Nile virus surveillance in Connecticut in 2000: an intense epizootic without high risk for severe human disease

In 1999, Connecticut was one of three states in which West Nile (WN) virus actively circulated prior to its recognition. In 2000, prospective surveillance was established, including monitoring bird deaths, testing dead crows, trapping and testing mosquitoes, testing horses and hospitalized humans with neurologic illness, and conducting a human seroprevalence survey. WN virus was first detected in a dead crow found on July 5 in Fairfield County. Ultimately, 1,095 dead crows, 14 mosquito pools, 7 horses, and one mildly symptomatic person were documented with WN virus infection. None of 86 hospitalized persons with neurologic illness (meningitis, encephalitis, Guillain-Barré-like syndrome) and no person in the seroprevalence survey were infected. Spraying in response to positive surveillance findings was minimal. An intense epizootic of WN virus can occur without having an outbreak of severe human disease in the absence of emergency adult mosquito management.

Identification of novel Saccharomyces cerevisiae proteins with nuclear export activity: cell cycle-regulated transcription factor ace2p shows cell cycle-independent nucleocytoplasmic shuttling

Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the NES receptor CRM1/Crm1p. We have carried out a yeast two-hybrid screen with Crm1p as a bait. The Crm1p-interacting clones were subscreened for nuclear export activity in a visual assay utilizing the Crm1p-inhibitor leptomycin B (LMB). This approach identified three Saccharomyces cerevisiae proteins not previously known to have nuclear export activity. These proteins are the 5' RNA triphosphatase Ctl1p, the cell cycle-regulated transcription factor Ace2p, and a protein encoded by the previously uncharacterized open reading frame YDR499W. Mutagenesis analysis show that YDR499Wp contains an NES that conforms to the consensus sequence for leucine-rich NESs. Mutagenesis of Ctl1p and Ace2p were unable to identify specific NES residues. However, a 29-amino-acid region of Ace2p, rich in hydrophobic residues, contains nuclear export activity. Ace2p accumulates in the nucleus at the end of mitosis and activates early-G(1)-specific genes. We now provide evidence that Ace2p is nuclear not only in late M-early G(1) but also during other stages of the cell cycle. This feature of Ace2p localization explains its ability to activate genes such as CUP1, which are not expressed in a cell cycle-dependent manner.

Mental health services. Called to the bench

All mental health providers must be part of a benchmarking group by December. A group of 26 inner city trusts have developed key indicators and found them useful in monitoring their progress. Research has been useful in highlighting service improvements and remaining areas of difficulty.

Mechanical performance of standard and cannulated 4.0-mm cancellous bone screws

The mechanical performance of bone screws is determined by their pull-out strength (holding power), compressive force, stripping torque, yield bending moment, ultimate bending moment, and fatigue strength. These parameters are related to the parameters of the screw design, including major thread diameter, minor thread diameter, thread length, pitch, shaft diameter, cannulation diameter, and material properties. The goal of the study was to theoretically predict the static performance of five 4.0-mm, 45-46-mm-long, cancellous, partially threaded standard and cannulated bone screws and compare the predictions with experimental measurements. A secondary goal was to determine if cannulation of the bone screw diminished its mechanical performance. The predicted values for pull-out force, compressive force, and stripping torque were determined by the thread length, major thread diameter, and thread shape factor. The screws with the largest major thread diameter and longest thread length had the greatest pull-out force, compressive strength, and stripping torque. However, when correcting for the thread length, a higher thread shape factor compensated for a smaller major diameter. The coefficient of determination (r2) for the correlation between the predicted and measured pull-out force improved from 0.75 to 0.90 when the theoretical model included the thread shape factor. The yield and ultimate bending moments are a function of the section modulus and material properties of the screw. The Ace solid screw had the greatest section modulus and yield and ultimate bending moments. The experimental data support the theoretical models for predicting the mechanical performance of bone screws. The design of the bone screws can be optimized on the basis of theoretical modeling. The strong correlation between the predicted and measured parameters allows comparison between bone screws without repeated experimental tests. Theoretical and experimental results show that cannulation of the bone screw did not inherently diminish its mechanical performance.

Genetic analysis of insulin-like growth factor II and HLA-G in pre-eclampsia

Pre-eclampsia (PE) is uniquely a disease of pregnancy and is the major cause of foetal and maternal morbidity and mortality. Epidemiological studies show that PE is highly heritable, with a high incidence in all populations. The underlying pathology indicates that absent or shallow invasion of foetal trophoblasts into maternal arteries is a feature of true PE. The objective of this study was to determine the genetic factors influencing PE. A large number of mother-father-baby trios were collected in which the first pregnancy was complicated by severe PE. After careful examination of the epidemiology and pathology of the disease, two plausible candidate genes, namely insulin-like growth factor II (IGF-II) and HLA-G, were analysed for association with PE. No association was found between a commonly occurring polymorphism in IGF-II and PE. Three polymorphisms in HLA-G were analysed in the sample cohorts. No association was found between three polymorphisms in HLA-G and PE. However, the frequency of the HLA-G insertion/deletion polymorphism in exon 8 deviated significantly from Hardy-Weinberg expectations in PE off-spring, reflecting an excess of heterozygotes for these polymorphisms in PE offspring. The significance of this deviation is not clear and further genetic analysis will be necessary to confirm this finding and to explore further the candidacy of HLA-G in PE.

Genetics and pathogenesis of malignant hyperthermia

Malignant hyperthermia (MH) is a potentially life-threatening event in response to anesthetic triggering agents, with symptoms of sustained uncontrolled skeletal muscle calcium homeostasis resulting in organ and systemic failure. Susceptibility to MH, an autosomal dominant trait, may be associated with congenital myopathies, but in the majority of the cases, no clinical signs of disease are visible outside of anesthesia. For diagnosis, a functional test on skeletal muscle biopsy, the in vitro contracture test (IVCT), is performed. Over 50% of the families show linkage of the IVCT phenotype to the gene encoding the skeletal muscle ryanodine receptor and over 20 mutations therein have been described. At least five other loci have been defined implicating greater genetic heterogeneity than previously assumed, but so far only one further gene encoding the main subunit of the voltage-gated dihydropyridine receptor has a confirmed role in MH. As a result of extensive research on the mechanisms of excitation-contraction coupling and recent functional characterization of several disease-causing mutations in heterologous expression systems, much is known today about the molecular etiology of MH.

An outbreak of multidrug-resistant Salmonella typhimurium food poisoning at a wedding reception

An outbreak of gastrointestinal illness among 127 persons attending a wedding reception in Dublin was investigated. One hundred and fifteen wedding guests were interviewed and information obtained about demographic and clinical characteristics, and food consumed at the reception. Faecal samples from ill guests were submitted for microbiological examination and environmental investigations conducted at the catering facilities. Fifty-eight cases (diarrhoea within three days after having eaten at the reception) were identified. Forty-six cases submitted stool samples, of which 39 were culture positive for Salmonella typhimurium. Two isolates were phage-typed and found to be DT 104. Turkey was identified as a potential vehicle for this outbreak. A sample of litter from young birds at the poultry farm which had supplied the turkeys also tested positive for Salmonella Typhimurium DT104. In the Republic of Ireland S.typhimurium accounts for almost 50% of all human salmonella isolates. Epidemiological and microbiological studies which relate the human and animal spectrum of this disease need to be undertaken as a priority.

Coexistent Hirschsprung's disease and esophageal achalasia in male siblings

Achalasia of the esophagus developed in two male siblings soon after birth, and they were successfully treated by surgery. Persistent signs resulted in the later diagnosis of Hirschsprung's disease. One required subtotal colectomy and ileoanal anastomosis, and the other is managing well on conservative treatment. Genetic analysis of the genes encoding the RET protooncogene, endothelin-3, and the endothelin-3 receptor did not show any defect. Familial achalasia of the esophagus in combination with Hirschsprung's disease has never been reported.

The yeast nucleoporin rip1p contributes to multiple export pathways with no essential role for its FG-repeat region

The FG-repeat domain of the yeast Rip1 protein (Rip1p) was identified initially as a possible target for the nuclear export signal (NES) of the HIV-1 Rev protein in a yeast two-hybrid assay. Rip1p is inessential, associated with nuclear pore complexes, and structurally related to the FG-nucleoporin family of pore proteins. It contributes to HIV-1 Rev-mediated RNA export and is also important for the export of heat shock RNAs at 42 degrees C. We show here that Rip1p is essential for the export of heat shock RNAs, and this function is fulfilled by the unique carboxyl terminus of Rip1p with no substantial contribution from the FG-repeat region. Genetic interactions between Rip1p and the RNA export mediator Gle1p are described, which support a role of the carboxyl terminus of Rip1p in poly(A)+ RNA export. Finally, this domain of Rip1p also contributes to Rev-mediated RNA export. The data suggest that Rip1p promotes the nuclear export of different classes of substrates by contributing to optimal pore function.

An outbreak of Salmonella enteritidis food poisoning in a psychiatric hospital in Dublin, Ireland

On 29 August 1996 Ireland's Eastern Health Board (EHB) was informed of an outbreak of gastrointestinal illness in a psychiatric hospital in Dublin. Fifty people among 240 members of staff and 183 patients had reportedly fallen ill since 27 August and new

Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD

From approximately one week before normal ovulation resumes, lactating women require protection against pregnancy by a contraceptive that is safe for both infant and mother in a multicenter one-year study, the natural hormone, progesterone, delivered vaginally by a sequence of four contraceptive rings designed for continuous use, was evaluated as a contraceptive for nursing mothers in comparison with the Copper T 380A IUD. Individual rings release in effective average dose of 10 mg day for a 3 month period. Evaluation included measures of lactational performance as well as of contraceptive efficacy and safety to mother and child. Nine participating clinics enrolled 802 ring users and 734 IUD acceptors between postpartum days 29 and 63. Life table analyses were performed with parallel decrements for ring and IUD subjects. Continuation in the study and analysis required that subjects not stop breastfeeding. The ring, with a one-year pregnancy rate of 1.5 per 100, did not differ significantly from the IUD with respect to contraceptive effectiveness (p > 0.05). More than half of the ring subjects were continuing at 6 months post admission and a quarter (23.5 per hundred) were still using the ring and breastfeeding one year after admission. Women with the IUD, however, had higher continuation rates (p < 0.001) at both time points. The largest single decrement for each method was that for weaning. Ring users had more complaints of vaginal problems but had fewer vaginal disorders on examination. At 12 months postpartum, 46 per 100 continuing ring users remained in amenorrhea. Lactation performance and the health and weight gain of the infants were similar among users of either regimen.

Identification of heterozygous and homozygous individuals with the novel RYR1 mutation Cys35Arg in a large kindred

BACKGROUND

Malignant hyperthermia (MH) is a potentially fatal, often autosomal dominant, disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anesthetics. In this article, the authors describe a malignant hyperthermia susceptible (MHS) kindred in which both parents of the proband are MHS and are first-degree cousins. Haplotype analysis in this kindred with chromosome 19 linked markers revealed that the proband and another sibling were homozygous for the affected RYR1 allele.

METHODS

Eighteen members of this large pedigree were investigated, with a clinical examination for signs of a myopathy, a caffeine halothane contracture test, a histo-enzymologic study on the muscle biopsies, and linkage analysis on genomic DNA isolated from family blood samples. RYR1 cDNA was amplified by polymerase chain reaction and was cloned and sequenced, facilitating mutation detection.

RESULTS

Linkage analysis demonstrated linkage between RYR1-linked markers and MH susceptibility in this family. DNA sequencing identified a T to C transition at nucleotide position 103, resulting in the substitution of an arginine for cysteine 35, representing the most N-terminal mutation reported to date in the RYR1 gene. This mutation segregates fully with the MHS trait, generating a lod score of 4.65 in favor of linkage to MHS at a recombination frequency of 0.0.

CONCLUSIONS

The proband in this kindred is the first reported homozygote to have presented with an MH episode. The homozygotes in this pedigree do not have an overt myopathy. The sensitivity of muscle samples to caffeine clearly distinguished the two homozygotes from other heterozygous-susceptible individuals. No clear differentiation was observed with the halothane contracture results.

Randomized cross-over study of a 21-day versus a 28-day hormone replacement therapy (HRT)

OBJECTIVE

To compare the occurrence of climacteric symptoms at two points in the cycle, identified as minE (phase of minimum estrogen effect) and MaxP (phase of maximum progesterone effect).

METHODS

Prospective randomized cross-over study in postmenopausal women currently on HRT comparing two opposed, sequential formulations: a regimen of 21 tablets containing estradiol valerate (EV) opposed with cyproterone acetate (CPA) in the last 10 tablets, versus a regimen of 28 tablets of conjugated equine estrogens (CEE), the last 12 tablets of which were taken together with norgestrel (NG).

OUTCOME MEASURES

Incidence of 24 climacteric complaints assessed at the specified days of the cycle corresponding to minE (day 6 or 7) and MaxP (day 27 or 28)

RESULTS

Contrary to the hypothesis that estrogen-dependent symptoms will recur at minE of the 21-day regimen, no significant differences were noted with the regimen containing 28 days of CEE, which served as the control. There were more complaints with the CEE+NG formulation at both minE and MaxP. Of the 38 patients, 63% preferred the EV+CPA regimen, 18.4% the CEE+NG regimen and 18.4% rated both preparations as equal.

CONCLUSIONS

The 7-day pause in the 21-day formulation containing EV+CPA did not affect efficacy; it was as effective in relieving climacteric symptoms as the regimen containing 28 days of estrogen. Based on the frequency of complaints both at minE and MaxP, the EV+CPA formulation induced a more acceptable symptom and mood profile.

RNA structural patterns and splicing: molecular basis for an RNA-based enhancer

Efficient splicing of the 325-nt yeast (Saccharomyces cerevisiae) rp51b intron requires the presence of two short interacting sequences located 200 nt apart. We used the powerful technique of randomization-selection to probe the overall structure of the intron and to investigate its role in pre-mRNA splicing. We identified a number of alternative RNA-RNA interactions in the intron that promote efficient splicing, and we showed that similar base pairings can also improve splicing efficiency in artificially designed introns. Only a very limited amount of structural information is necessary to create or maintain such a mechanism. Our results suggest that the base pairing contributes transiently to the spliceosome assembly process, most likely by complementing interactions between splicing factors. We propose that splicing enhancement by structure represents a general mechanism operating in large yeast introns that evolutionarily preceded the protein-based splicing enhancers of higher eukaryotes.

The prevalence of symptoms in menopausal women in the Far East: Singapore segment

Questionnaires (4000) on experience of menopausal symptoms in Singaporean women aged 40-55 were distributed by students. In total, 524 envelopes were returned (13.1%) and of these 420 were analyzed. Of these, 366 were classified as either pre-, peri- or postmenopausal on the basis of their menstrual patterns. Menopausal symptoms in this sample of Singaporean women were, in general, similar to those experienced in the West though the prevalence was low compared to European studies. No significant differences in individual symptoms were found between the 3 groups but, taken together, symptoms were significantly highest in the perimenopausal and lowest in the other menopausal groups. In the postmenopausal group 50% had been menopausal for at least 1 year at 50.5 years.

Acetaminophen ingestion in childhood--cost and relative risk of alternative referral strategies

Acetaminophen is the pharmaceutical most frequently ingested by small children. Although past research has allowed the safe management of 90% of these ingestions at home, several thousand are still referred to emergency departments annually. With the goal of further reducing the number of unnecessary referrals, the risk/benefit considerations of alternate referral strategies were analyzed. In a retrospective poison center chart review study from 11 centers, the records of children between the ages 1 and 6 years who acutely ingested acetaminophen and were referred to a hospital for determination of serum acetaminophen concentration in 1986 and 1987 were identified using the database of the American Association of Poison Control Centers. Risk of hepatic injury was assigned on the basis of the Rumack-Matthew acetaminophen toxicity nomogram. The cohort was stratified in terms of the amount ingested and whether a pediatric or adult preparation was ingested. The direct cost of an evaluation was estimated from four centers. Sensitivity, specificity and direct cost of each risk identification strategy were calculated. Eight hundred sixty six of 2091 patients had a timed serum acetaminophen concentration recorded. Of these, three patients had results in the "probable risk" area of the nomogram. A referral reduction strategy which would refer only children who ingest 200 mg/kg or more of an adult preparation could eliminate 82% of referrals without missing any of these "probable risk" patients. Six other children were determined to have serum acetaminophen concentrations in an area of the nomogram labeled "possible risk". No referral reduction strategy explored identified all of these patients. The average charge for an emergency department evaluation in 1992 was $272.00. These data suggest that children less than six years of age who ingest pediatric acetaminophen products other than those from packages containing greater than 30 tablets or who ingest less than 200 mg/kg of an adult preparation may be safely managed at home without referral to a hospital. This strategy would result in significant cost savings and prevent unnecessary inconvenience to many patients and families.

Influence of time until emesis on the efficacy of decontamination using acetaminophen as a marker in a pediatric population

STUDY OBJECTIVE

To determine the extent of drug removal by emesis at different times after the ingestion of a toxic substance.

DESIGN

Multicenter retrospective chart review.

METHODS

Using the American Association of Poison Control Centers' aggregate data base, children who had ingested acetaminophen and who were referred to a health care facility by one of 11 poison centers during a two-year period were identified. Charts of these patients were reviewed to determine the quantity ingested per kilogram of body weight, method of decontamination used, the timing of decontamination, and the serum acetaminophen concentration obtained four hours after ingestion.

RESULT

Charts of 455 patients met all requirements for inclusion. When emesis occurred within one-half hour after ingestion, mean serum acetaminophen concentration drawn four hours after ingestion was approximately half that in a control group that received no decontamination. Emesis had less impact when it was delayed further and had no demonstrable impact when it occurred more than 90 minutes after ingestion.

CONCLUSION

Many factors must be considered when deciding if and by what method a given patient should receive decontamination. When delayed gastric emptying is not expected, emesis can at best decrease a toxic burden by half if it occurs early. Medical care givers must continue to scrutinize management practice to ensure that syrup of ipecac is given only in situations in which it is likely to make a difference in outcome and in which it is the most effective agent to achieve this goal.

Use of two types of estradiol-releasing skin patches for menopausal patients in a tropical climate

As part of a program to evaluate nonoral routes for delivery of estrogen replacement therapy at the National University Hospital, Singapore, we assessed two different 50 micrograms estradiol patches. The first study (patch A) was terminated because of a high rate of skin reactions. Tests of the components of this patch identified the alcohol carrier as the cause of these reactions when combined with an occlusive membrane in the tropical Singapore climate. A subsequent clinical trial with 21 female subjects was undertaken with a different 50 micrograms estradiol patch (patch B). Twenty patients completed the 6-month study. Patch B was as effective as patch A, caused fewer skin reactions, and adhered better.

Rates and outcomes of planned pregnancy after use of Norplant capsules, Norplant II rods, or levonorgestrel-releasing or copper TCu 380Ag intrauterine contraceptive devices

OBJECTIVES

The objectives were to measure rates of planned pregnancy and factors affecting these rates after use of very-long-acting contraceptive methods (Norplant or Norplant II implants, a levonorgestrel-releasing intrauterine contraceptive device, or the copper T (model TCu 380Ag) intrauterine contraceptive device.

STUDY DESIGN

The design was a concurrent, multicenter prospective study of 372 women who stopped contraception for planned pregnancy. Analysis was by life-table, log-rank, and standard chi 2 methods.

RESULTS

Pregnancy rates 12 and 24 months after cessation of contraceptive use were 82 and 89 per 100, respectively. Age at removal and family planning intentions at initiation of contraception were both significantly correlated with pregnancy rates (p less than 0.05), but former contraceptive regimen and duration of contraceptive use were not. Pregnancy outcomes did not deviate from normal limits and did not differ by contraceptive formerly used.

CONCLUSION

Contraceptive implants releasing 30 micrograms/day of levonorgestrel or intrauterine contraceptive devices releasing 20 micrograms/day of levonorgestrel or having copper surface areas of 380 mm2 are associated with normal fertility after use for women seeking pregnancy at termination. Durations of use do not affect pregnancy rates.

Voluntary activation of human quadriceps during and after isokinetic exercise

The extent of voluntary activation in fresh and fatigued quadriceps muscles was investigated during isometric and isokinetic voluntary contractions at 20 and 150 degrees/s in 23 normal human subjects. The muscles were fatigued by a total of 4 min of maximal knee extension at an angular velocity of 85 degrees/s. Voluntary activation was determined by the superimposition of tetanic electrical stimulation at 100 Hz for 250 ms, initiated at a constant knee angle. The relationship between voluntary and stimulated force was similar to that found with the established twitch superimposition technique used on isometric contractions. In fresh muscle all the subjects showed full voluntary activation during isometric contractions. Some activation failure was seen in five subjects at 20 degrees/s [2.0 +/- 0.9 degrees (SE)] and in two subjects at 150 degrees/s (0.7 +/- 0.5). After fatigue all subjects showed some activation failure at 0 and 20 degrees/s (36.4 +/- 3.1 and 28.8 +/- 4.1 degrees, respectively), but only two showed any at 150 degrees/s (1.4 +/- 5.7). We conclude that brief high-intensity dynamic exercise can cause a considerable failure of voluntary activation. This failure was most marked during isometric and the lower-velocity isokinetic contractions. Thus a failure of voluntary activation may have greater functional significance than previous studies of isometric contractions have indicated.

Long-term contraception with the levonorgestrel 20 mcg/day (LNg 20) and the copper T 380Ag intrauterine devices: a five-year randomized study

An intrauterine device, releasing approximately 20 micrograms/day of levonorgestrel (LNg 20), used by 1124 women, was studied in a randomized trial of five years duration in comparison with the Copper T, model TCu 380Agm in 1121 women. At five years, the gross cumulative pregnancy rate of 1.1 +/- 0.5 per 100 among users of the LNg 20 devices was not significantly different from the rate of 1.4 +/- 0.4 per 100 experienced by users of the Copper T 380Ag. The steroid-releasing IUD had significantly higher termination rates for expulsion and amenorrhea, a significantly lower termination rate for other menstrual problems and pain, and a lower continuation rate. The five-year continuation rate among women using the TCu 380Ag was 40.6 per 100 as compared with that of 33.0 per 100 among women randomized to the LNg 20 device (P less than .001). Terminations attributed to amenorrhea with the LNg device primarily account for differences in continuation. These two intrauterine devices are the most effective long-term, reversible IUDs yet reported in the literature. No other contraceptive methods have exhibited such low long-term pregnancy rates in randomized comparative trials.

Current concepts on the use of IUDs

IUDs have been used in Singapore since the mid 1960's but acceptance of this contraceptive method has fluctuated widely as a result of misconceptions regarding possible complications. The current generation of copper bearing devices have pregnancy rates below 1 per 100 women per year and this rate falls further with continued use. New developments which hold promise include a device releasing 20 mcg levonorgestrel per day and a copper device without a plastic frame which may reduce menstrual blood loss and dysmenorrhoea. In addition to the well established contra-indications to use, a past history of pelvic inflammatory disease or ectopic pregnancy, promiscuity, nulliparity and age less than 25 are now considered relative contraindications.

Use of an intraaortic balloon pump as a pneumatic ventricular assist device controller

Using a circulatory analogue, we investigated sequentially the performance of a dedicated ventricular assist device driver and an intraaortic balloon pump when driving a pneumatic ventricular assist device. Each drive device was compared under identical pumping conditions at rates of 40 to 120 cycles/min against two resistances. Our preliminary study showed that a modified intraaortic balloon pump could drive a pneumatic ventricular assist device as effectively as its dedicated driver. The necessary modifications to and possible further development of the intraaortic balloon in this role are discussed.

Isolation of growth factors from adult bovine bone

Fetal rat calvariae synthesize transforming growth factor beta (TGF beta), beta 2 microglobulin (beta 2 m), and insulinlike growth factor I (IGF I), but, except for TGF beta, it is not known if these polypeptides are also present in adult bone tissue. Pulverized bovine bone, extracted with 0.5 N HCl and 4 M guanidine HCl and fractionated by gel filtration, was found to contain several biologically active components when tested for its effects on DNA synthesis in osteoblast-rich cell cultures. TGF beta, beta 2 m, and IGF I were identified and further purified using high performance liquid chromatography (HPLC). TGF beta, identified by a standard TGF beta bioassay or by immunoreactivity, was purified by muBondapak C18 and muBondapak CN reversed phase HPLC. beta 2 m, identified by immunoreactivity, required an additional fractionation step on a DEAE-HPLC column for complete purification. IGF I, identified by immunoreactivity, was purified by HPLC using a muBondapak C18 and a DEAE-HPLC column. Purified TGF beta, beta 2 m, and IGF I migrated as single bands on polyacrylamide gel electrophoresis with respective molecular masses of 24,000, 10,000, and 7,500. In conclusion, adult bone matrix, like fetal bone cultures, contains TGF beta, beta 2 m, and IGF I and these factors may play a role in adult skeletal remodeling.

Pentoxifylline inhibits granulocyte and platelet function, including granulocyte priming by platelet activating factor

Pentoxifylline has been claimed to work a beneficial effect in arterial insufficiency by improving erythrocyte deformability and thus improving blood flow. A number of observations, including the drug concentrations required to work the red cell effect, suggested that this was not likely to be a complete explanation. We therefore examined the effect of pentoxifylline on several granulocyte and platelet functions. Pentoxifylline inhibited platelet aggregation in response to 4 mumol/L adenosine diphosphate; although statistically significant inhibition was seen at 1 mumol/L pentoxifylline, over 200 mumol/L was required for 50% inhibition. The adherence of unstimulated platelets to cultured endothelial cells was not strongly inhibited by pentoxifylline; however, the additional increment in adherence seen in the presence of thrombin was strongly inhibited (50% attenuative dose [AD50] = 18 mumol/L). Granulocyte aggregation in response to C5a was modestly inhibited (AD30 approximately equal to 8 mumol/L; AD50 greater than 1 mmol/L), and the adherence of unstimulated polymorphonuclear neutrophils (PMNs) to endothelium was uninhibited. The C5a-mediated augmentation of PMN adherence to endothelium was mildly inhibited (AD50 = 240 mumol/L). Inhibition of PMN chemotaxis to N-Formyl-methionyl-leucyl-phenylalanine (FMLP) or C5a (AD50 = 12 mumol/L) and inhibition of superoxide production in response to FMLP-cytochalasin B (AD50 = 24 mumol/L) were seen at more clinically credible concentrations. Perhaps most important, pentoxifylline blocked the ability of platelet activation factor to prime neutrophils for enhanced response to subsequent stimuli (AD50 approximately equal to 8 mumol/L; AD60 = 10 mumol/L when production was the indicator system); in vivo, this could broaden the drug's effect to include functions that it does not inhibit potently in a primary fashion. Although pentoxifylline is known to be a phosphodiesterase inhibitor, and we found it to elevate intracellular cyclic adenosine monophosphate in stimulated PMNs, we found it to be only marginally more potent than theophylline in this regard; therefore, the failure of theophylline to inhibit PMN priming suggests that this enzyme inhibition is not a complete explanation of the pharmacologic action of pentoxifylline. We suggest that the effects of pentoxifylline on platelet and granulocyte function are likely to contribute to the drug's clinical efficacy.

Effects of basic fibroblast growth factor on bone formation in vitro

Basic fibroblast growth factor (bFGF) was studied for its effects on bone formation in cultured rat calvariae. bFGF at 0.1-100 ng/ml stimulated [3H]thymidine incorporation into DNA by up to 4.4-fold. bFGF also increased the number of colcemid-induced metaphase arrested cells and the DNA content. Transient (24 h) treatment with bFGF enhanced [3H]-proline incorporation into collagen 24-48 h after the factor was removed; this effect was DNA synthesis dependent and blocked by hydroxyurea. The collagen stimulated by bFGF was type I, and this effect was observed primarily in the periosteum-free bone. In contrast, continuous treatment with bFGF for 24-96 h inhibited [3H]proline incorporation into type I collagen. bFGF did not alter collagen degradation. In conclusion, bFGF stimulates calvarial DNA synthesis, which causes an increased number of collagen-synthesizing cells, but bFGF has a direct inhibitory effect on collagen synthesis.

Isolation and characterization of insulin-like growth factor I (somatomedin-C) from cultures of fetal rat calvariae

Cultured bones have been shown to secrete local regulators of bone remodeling, such as beta 2-microglobulin, transforming growth factor-beta, and insulin-like growth factor (IGF), but the IGF secreted has not been characterized. In the present study, IGF from medium conditioned by 21-day-old fetal rat calvariae was isolated and characterized. IGF was purified using dialysis, gel filtration, and reverse phase HPLC. Amino acid composition was compatible with that of IGF I (somatomedin-C), and amino-terminal sequence analysis revealed homology with IGF-I. The concentration of IGF-I in the calvarial culture medium was 1 nM and was suppressed by cycloheximide. Calvaria-derived rat IGF I at 20 nM stimulated DNA and collagen synthesis by 42% and 26%, respectively, in monolayer cultures of osteoblast-rich rat parietal bone cells. This study indicates that locally produced IGF-I regulates bone formation in cultures of 21-day-old fetal rat calvariae.

Interim 4-year results of a comparative study between the Nova T and the Multiload 250

Eight-hundred patients recruited between September 1981 and December 1984 were admitted to a randomized prospective trial of the Nova T (NTCu200Ag) and Multiload 250 (MLCu250) IUDs. At the cut off date, 31 December 1986, 206 patients had completed the 4-year trial period, 379 had terminated before completion and 215 were in the fourth year of use. For the third and fourth years, the MLCu250 had a significantly lower accidental pregnancy rate (p less than 0.05).

A bone-derived growth factor isolated from rat calvariae is beta 2 microglobulin

Rat calvariae are known to secrete a bone-derived growth factor (BDGF) that stimulates bone DNA and collagen synthesis. BDGF was purified from calvarial culture medium with dialysis, gel filtration and HPLC. Amino acid composition of BDGF was compatible with murine beta 2 microglobulin (beta 2 m), and amino terminal sequence analysis revealed identity with mature murine beta 2 m. This was confirmed by Western blot analysis using a polyclonal antibody to beta 2 m. Like BDGF, human beta 2 m stimulated bone DNA, collagen and noncollagen protein synthesis. Thus, BDGF, an autologous regulator of bone formation, is homologous to beta 2 m.

Evaluation of a low dose of hepatitis B vaccine given within a childhood immunisation programme in Singapore

The feasibility of introducing low dose (5 micrograms) hepatitis B (HB) virus vaccination at birth and again 1 and 2 months later as part of an existing primary immunisation programme of childhood, was assessed in 662 healthy newborn Singapore children. The vaccine (B-Hepavac, Menck, Sharp and Dohme) was given to three neonatal groups: those born to HB surface antigen (sAg)-negative mothers, HBsAg-positive/HBeAg-positive mothers and HBsAg-positive/HBeAg-negative mothers. A dose of 5 micrograms was compared in a randomised study with the more usual 10 micrograms dose given at the same intervals. Neonates born to HBsAg-positive/HBeAg-positive mothers were also given hepatitis B immunoglobulin (HBIg) at birth. The 5 microgram dose of vaccine was as immunogenic as the 10 microgram dose in all three groups of children studied. At 1 year, anti-HBsAg seroconversion among infants of antigen-negative mothers was 95.8% for the 5 microgram dose and 91.9% for the 10 microgram dose. Suppression of anti-HBsAg formation was not seen even when maternal anti-HBsAg was present or HBIg given. Among infants born to HBsAg-positive/HBeAg-positive mothers, passive plus active immunisation was 100% protective at doses of 5 micrograms and 10 micrograms vaccine in the newborns who were HBsAg-negative at 24 h. Seroconversion after both the 5 and 10 microgram doses of vaccine was reduced, however, to 88% in each group of infants who were already HBsAg-positive at 24 h of age. Overall, passive plus active immunisation as well as HB vaccine alone (5 micrograms dose), given within the existing but expanded primary immunisation programme of childhood, was effective in preventing infection and the chronic carrier state in newborns exposed to risk of HB virus infection during infancy.

Postabortion insertion of the Nova T and MLCu250: preliminary results of a comparative study

This 4-year prospective randomized study is designed to compare the effectiveness and complication rates of the Nova T and MLCu250 inserted immediately postabortion. At the cut-off date (30 November 1983), all patients in the first cohort of 400 women had completed at least 12 months of use. At this stage of the trial, no significant differences had emerged between the two devices in any of the standard termination categories.

Effect of benztropine on the diurnal prolactin responses to haloperidol

Prolactin (PRL) responses to haloperidol were investigated at 0900 and 1800 h in six young healthy men under basal conditions and after benztropine mesylate administration. Haloperidol administration induced significantly higher PRL release during the evening compared to the morning. The anticholinergic drug, benztropine, potentiated the PRL responses to haloperidol both in the morning and in the evening. The possible mechanisms of these findings are discussed.

Intrauterine devices and pelvic inflammatory disease

There is convincing clinical evidence that PID is more common in IUD users than in users of other contraceptive methods. There appears to be a smaller but significant increase when IUDs are compared with sexually active noncontraceptive users. However, the incidence of PID severe enough to warrant hospitalization is only of the order of 1 to 2 per 1,000 women per year. The question which remains is whether beyond this low figure of moderate and severe disease there is a much higher incidence of subclinical PID which may result in complications for IUD users. Development of a marker such as C-Reactive protein or the split complement component C3d to detect mild PID would prove invaluable in the elucidation of several crucial problems in the clinical management of women using IUDs.

Effect of atropine on the diurnal PRL responses to TRH in normal subjects

Prolactin (PRL) responses to TRH were investigated at 0900 and 1800 hr in six young healthy men under basal conditions and after atropine administration. TRH induced significantly higher PRL release during the evening administration compared to the morning. Atropine had no effect on basal PRL secretion. Unlike the reported influences of anticholinergic drugs on the diurnal PRL responses to other stimuli, atropine also had no effect on TRH-stimulated PRL release either in the morning or in the evening. These observations in part may be accounted for by the direct PRL-releasing effect of TRH (without neurotransmitter involvement).

A randomised comparative evaluation of the copper 7, multiload copper 250 and T copper-22OC IUDs

Two new Cu-IUDs, the TCu-22OC and Multiload Cu250, were evaluated against the Cu7 in 1,199 subjects in a randomised, multicentric trial using a common study protocol. During the 2 years following insertion, cumulative first-segment rates for total use-related terminations showed no significant differences between the 3 devices; however, the Cu7 had a significantly higher termination rate for accidental pregnancy compared to the TCu-22OC and its expulsion rate was significantly higher than the ML Cu250. The rate of accidental pregnancy was higher and the expulsion rate lower with the ML Cu250 compared to the TCu-22OC but these differences were not significant. The results are discussed in relation to IUD design and their application in family planning.