Kirkpatrick-Baez microscope for hard X-ray imaging of fast ignition experiments.

A Kirkpatrick-Baez X-ray microscope has been developed for use on the Titan laser facility at the Lawrence Livermore National Laboratory in Fast Ignition experiments. It was developed as a broadband alternative to narrow band Bragg crystal imagers for imaging Kα emission from tracer layers. A re-entrant design is employed which allows for alignment from outside the chamber. The mirrors are coated with Pt and operate at a grazing incident angle of 0.5° providing higher resolution than an equal brightness pinhole and sufficient bandwidth to image thermally shifted characteristic Kα emission from heated Cu tracer layers in Fast Ignition experiments. The superpolished substrates (<1 Å rms roughness) had a final visible wavelength roughness of 1.7 Å after coating, and exhibited a reflectivity corresponding to an X-ray wavelength roughness of 7 ± 1 Å. A unique feature of this design is that during experiments, the unfiltered direct signal along with the one-dimensional reflections are retained on the detector in order to enable a live indication of alignment and incident angle. The broad spectral window from 4 to 9 keV enables simultaneous observation of emission from several spectral regions of interest, which has been demonstrated to be particularly useful for cone-wire targets. An experimentally measured resolution of 15 µm has been obtained at the center of the field of view.

Low birthweight at a Papua New Guinea highlands hospital.

A prospective case-control study involving 75 low birthweight (LBW) babies and 224 controls was carried out at the Mount Hagen General Hospital over a period of 7 months, from June to December 1997. Identified risk factors for LBW in this population included maternal age (age less than 22 years or over 35 years, p = 0.03), a birth interval of less than 2 years (p = 0.006), no antenatal booking (p = <0.005), low attendance at antenatal clinic (p = <0.005), fever during pregnancy (p = <0.005), PET (p = 0.05), APH (p = <0.015), and maternal smoking during pregnancy (p = 0.008). Other well-established risk factors for LBW, i.e. small stature, low body mass index (BMI), haemoglobin less than 8 g/dl, and low educational attainment, appeared to be more frequent in the mothers of the LBW babies than the controls but differences did not reach statistical significance. The results suggest the need for improved provision of, and efforts to increase the use of, antenatal and family planning services. The results also provide clear evidence of the deleterious effects of smoking during pregnancy in a developing country.

Antihirudin antibodies in patients with heparin-induced thrombocytopenia treated with lepirudin: incidence, effects on aPTT, and clinical relevance.

Hirudin, a potent and specific thrombin inhibitor, is a protein of nonhuman origin and therefore potentially immunogenic. The primary objectives of this investigation were to determine the incidence of antihirudin antibodies (ahir-ab) in patients with heparin-induced thrombocytopenia (HIT) who received lepirudin as parenteral anticoagulation and to determine the incidence of death, limb amputation, new thromboembolic complications (TECs), and major hemorrhage in patients who had ahir-ab, compared with patients who were ahir-ab negative. The investigation used data from 2 prospective multicenter studies with the same study protocol, in which HIT patients received 1 of 4 intravenous lepirudin dosage regimens. The treatment duration was 2 to 10 days. Ahir-ab were determined by a newly developed enzyme-linked immunosorbent assay (ELISA). Eighty-seven of 196 evaluable patients (44.4%) had ahir-ab of the IgG class. Development of ahir-ab was dependent on the duration of treatment (ahir-ab-positive patients 18.6 days vs ahir-ab-negative patients 11.8 days; P =.0001). Fewer ahir-ab-positive than ahir-ab-negative patients died (P =.001). Ahir-ab did not cause an increase in limb amputation (P =.765), new TECs (P >.99), or major bleedings (P =.549). In 23 of 51 (45.1%) evaluable patients in whom ahir-ab developed during treatment with lepirudin ( = 12% of all lepirudin treated patients), the ahir-ab enhanced the anticoagulatory effect of lepirudin. Ahir-ab are frequent in patients treated with lepirudin for more than 5 days. Ahir-ab are the first example for a drug-induced immune response causing enhanced activity of a drug. Therefore, during prolonged treatment with lepirudin, anticoagulatory activity should be monitored daily to avoid bleeding complications.

Perinatal asphyxia at Port Moresby General Hospital: a study of incidence, risk factors and outcome.

We investigated the incidence and outcome of perinatal asphyxia (PA) at Port Moresby General Hospital by a retrospective chart review and prospective collection of data, spanning a total of 2.5 years. 125 babies weighing more than 2000 g at birth with a gestation of 34 weeks or more and with no obvious congenital abnormalities were diagnosed to have PA. During the same time period 22,700 liveborn babies were delivered, a PA incidence of 5.5/1000 livebirths. There was a 31% mortality and considerable morbidity. Hospital records for 114 affected babies and 115 controls (the next baby born by normal delivery) were compared. Significant risk factors for PA were: previous stillbirth or neonatal death, fetal heart rate abnormalities, membranes ruptured for more than 12 hours prior to delivery, meconium staining, antepartum haemorrhage, maternal fever, prolonged first and second stages of labour, preterm or post-term delivery and operative delivery. In only 73 affected babies was the 5-minute Apgar score recorded as 6 or less. All 34 of the babies with grade 3 hypoxic ischaemic encephalopathy (HIE) either died (30) or had serious neurological impairment. The treatment of affected babies remains largely supportive and some causes of PA are currently unavoidable. It is, however, widely accepted that some cases of perinatal asphyxia may be prevented by the delivery of high-risk pregnancies in obstetric facilities with appropriate intervention and by good neonatal resuscitation. Sophisticated or expensive equipment is not a necessity.

Protection of breastfeeding in Papua New Guinea.

In Papua New Guinea the bottle-feeding of babies has been increasing, predominantly among unemployed women of low educational status. Many women are unaware of their legal right to have breaks at work for the purpose of breastfeeding, and a high proportion of workplaces have no facilities for mothers who wish to breastfeed their children. The laws on the feeding of infants should be updated and implemented, and an effort is needed to explain the benefits of breastfeeding and the rights of working mothers.

PIP: Among women leaving hospital after delivery in Port Moresby, Papua New Guinea, the proportion feeding their babies artificially increased from 6% in 1964 to 22% in 1974. However, bottle-feeding was known by health personnel to have devastating effects upon children's health. A 1976 survey conducted in 5 suburbs of the city found that a third of babies were artificially fed, of whom 69% were malnourished, compared to only 26% of breast-fed children similarly malnourished. Papua New Guinea's Baby Feed Supplies (Control) Act 1977 was issued to keep parents from obtaining feeding bottles except from registered pharmacists upon presentation of a prescription issued by a registered health worker. The Act also prohibits the advertising of breast milk substitutes. A 1979 survey in 4 of the 5 suburbs covered in 1976 found that only 11% of babies were being bottle-fed, indicating a positive short-term effect of the Act. Current policy favors exclusive breast-feeding for the first 4-6 months of a baby's life, no bottle-feeding in maternity or pediatric facilities, and active discouragement of such feeding. A 1995 multicenter infant feeding survey which collected feeding data on 1822 infants under age 2 years found that breast milk substitutes or other fluids were given to 1133 children, with bottles readily attained without prescription. Bottle-feeding was common in all of the provincial centers studied, with the highest prevalence being 35% in the Western Highlands Province. The prevalence of bottle-feeding was positively correlated with the level of mother's education and her work status as a paid employee. 72% of the bottle-feeding mothers knew that such feeding practice can cause diarrhea, almost two-thirds of the working women were unaware that they were legally entitled to 2 half-hour breast-feeding breaks daily, and the existence of child care facilities at the workplace was reported by less than 5% of interviewees.

NDT80 and the meiotic recombination checkpoint regulate expression of middle sporulation-specific genes in Saccharomyces cerevisiae.

Distinct classes of sporulation-specific genes are sequentially expressed during the process of spore formation in Saccharomyces cerevisiae. The transition from expression of early meiotic genes to expression of middle sporulation-specific genes occurs at about the time that cells exit from pachytene and form the meiosis I spindle. To identify genes encoding potential regulators of middle sporulation-specific gene expression, we screened for mutants that expressed early meiotic genes but failed to express middle sporulation-specific genes. We identified mutant alleles of RPD3, SIN3, and NDT80 in this screen. Rpd3p, a histone deacetylase, and Sin3p are global modulators of gene expression. Ndt80p promotes entry into the meiotic divisions. We found that entry into the meiotic divisions was not required for activation of middle sporulation genes; these genes were efficiently expressed in a clb1 clb3 clb4 strain, which fails to enter the meiotic divisions due to reduced Clb-dependent activation of Cdc28p kinase. In contrast, middle sporulation genes were not expressed in a dmc1 strain, which fails to enter the meiotic divisions because a defect in meiotic recombination leads to a RAD17-dependent checkpoint arrest. Expression of middle sporulation genes, as well as entry into the meiotic divisions, was restored to a dmc1 strain by mutation of RAD17. Our studies also revealed that NDT80 was a temporally distinct, pre-middle sporulation gene and that its expression was reduced, but not abolished, on mutation of DMC1, RPD3, SIN3, or NDT80 itself. In summary, our data indicate that Ndt80p is required for expression of middle sporulation genes and that the activity of Ndt80p is controlled by the meiotic recombination checkpoint. Thus, middle genes are expressed only on completion of meiotic recombination and subsequent generation of an active form of Ndt80p.

Spe3, which encodes spermidine synthase, is required for full repression through NRE(DIT) in Saccharomyces cerevisiae.

We previously identified a transcriptional regulatory element, which we call NRE(DIT), that is required for repression of the sporulation-specific genes, DIT1 and DIT2, during vegetative growth of Saccharomyces cerevisiae. Repression through this element is dependent on the Ssn6-Tup1 corepressor. In this study, we show that SIN4 contributes to NRE(DIT)-mediated repression, suggesting that changes in chromatin structure are, at least in part, responsible for regulation of DIT gene expression. In a screen for additional genes that function in repression of DIT (FRD genes), we recovered alleles of TUP1, SSN6, SIN4, and ROX3 and identified mutations comprising eight complementation groups of FRD genes. Four of these FRD genes appeared to act specifically in NRE(DIT)mediated repression, and four appeared to be general regulators of gene expression. We cloned the gene complementing the frd3-1 phenotype and found that it was identical to SPE3, which encodes spermidine synthase. Mutant spe3 cells not only failed to support complete repression through NRE(DIT) but also had modest defects in repression of some other genes. Addition of spermidine to the medium partially restored repression to spe3 cells, indicating that spermidine may play a role in vivo as a modulator of gene expression. We suggest various mechanisms by which spermidine could act to repress gene expression.

Development of an anti-bleeding agent for recombinant hirudin induced skin bleeding in the pig.

Recombinant hirudin (rH) is a highly specific thrombin inhibitor which is under clinical investigation for various thrombotic disorders. However, one of its potential risks during clinical use might be hemorrhage, especially when combined with other agents interfering with the coagulation system like antiplatelet or fibrinolytic agents. In this experimental study we investigated whether Haemate, a von Willebrand Factor (vWF) and factor VIII containing product, could correct rH/aspirin induced bleeding in an experimental pig study. Skin bleeding time was evaluated in three open, placebo-controlled, randomized studies following comparable designs. A total of 62 animals were given a short-term infusion of aspirin (20 mg/kg) followed by a three-hour infusion of a high or low dose (0.3 or 0.5 mg/kg/h) of rH. At cessation of rH infusion, animals were allocated to treatment with either Haemate (30 FVIII U/kg) or the recombinant factor VIII, Helixate, which is devoid of vWF. The skin bleeding time (SBT, given as times of baseline) as measured four hours after the start of the rH infusion was defined as the prospective endpoint. In study 1 (low dose rH + Haemate) 4 h SBT was 2.18 (placebo) and 1.61 (Haemate, p = 0.0111). In study No. 2 (high dose rH + Haemate) SBT was 2.58 in placebo and 1.73 in Haemate (p = 0.0001). No significant difference between placebo and treatment were detected in study No. 3 (low dose rH + Helixate). Haemate but not Helixate significantly decreased bleeding time as compared to placebo at termination of the study (7 hours) which was defined as the secondary endpoint. No effect on either aPTT nor rH plasma levels were observed with any of the study drugs. It was concluded that Haemate decreases excess bleeding induced by rH/aspirin treatment without altering rH's anticoagulant effect.

Infant feeding practices in Papua New Guinea.

Concern about a possibly increasing prevalence of bottle-feeding led in 1995 to an Infant Feeding Survey of 1822 mothers attending urban health facilities. Infant feeding practices including feeding of colostrum, exclusive breastfeeding, weaning practices and bottle-feeding were assessed. This revealed that 28.8% of mothers had not given colostrum to their babies, that 43.5% of 3-month-old babies were exclusively breastfed, and that solids were introduced before 4 months of age in over half of the study population. Bottle-feeding was used by 20% of the study population. Feeding practices differed in women of Highlands and of Coastal origin. The findings emphasize the need to strengthen health education programmes which take into account the mothers' different cultural backgrounds. The issue of breast-feeding by mothers in paid employment needs to be addressed.

PIP: Recognizing the many benefits of breast-feeding, the government of Papua New Guinea (PNG) legislated to protect the practice 4 years before the introduction of the World Health Organization Code of Marketing restricting access to bottle feeding supplies. While exclusive breast-feeding for 4-6 months is recommended policy, it was noticed that many mothers introduce solids and fluids other than breast milk much earlier. In 1995, the Pediatric Society of PNG conducted a feeding survey to assess the prevalence of bottle feeding and review the effects of the imposed legislation. Infant feeding practices, including the feeding of colostrum, exclusive breast-feeding, weaning practices, and bottle feeding were assessed among 1822 mothers of children under age 2 years attending urban health facilities. 28.8% of the mothers had not given colostrum to their babies, 43.5% of 3-month old babies were exclusively breast-fed, and solids were introduced before age 4 months in more than half of the study population. 20% of the study population bottle fed. The prevalence of exclusive breast-feeding among employed Highlands women was lower than among employed Coastal women, but the difference was not statistically significant. Study findings point to the need to strengthen health education programs which take into account mothers' different cultural backgrounds. The issue of breast-feeding by mothers in paid employment also needs to be addressed.

An Ssn6-Tup1-dependent negative regulatory element controls sporulation-specific expression of DIT1 and DIT2 in Saccharomyces cerevisiae.

Sporulation of the yeast Saccharomyces cerevisiae is a process of cellular differentiation that occurs in MATa/MAT alpha diploid cells in response to starvation. The sporulation-specific genes DIT1 and DIT2, which are required for spore wall formation, are activated midway through the sporulation program, with maximal transcript accumulation occurring at the time of prospore enclosure. In this study, we have identified a negative regulatory element, termed NREDIT, that is located between the start sites of transcription of these divergently transcribed genes. This element, which prevents expression of the DIT1 and DIT2 genes during vegetative growth, reduces expression of a CYC1-lacZ reporter gene more than 1,000-fold and acts in an orientation- and position-independent manner. We found that the ability of NREDIT to turn of expression of the reporter gene and the chromosomal DIT1 and DIT2 genes in vegetative cells requires the Ssn6-Tup1 repression complex. Interestingly, NREDIT-mediated repression of the reporter gene is maintained during sporulation. Derepression during sporulation requires complex interactions among several cis-acting elements. These are present on an approximately 350-bp DNA fragment extending from NREDIT to the TATA box and an approximately 125-bp fragment spanning the TATA box of DIT1. Additionally, a region of NREDIT which is very similar in sequence to UASSPS4, an element that activates gene expression midway through sporulation, contributes both to vegetative repression and to sporulation-specific induction of DIT1. We propose a model to explain the requirement for multiple elements in overcoming NREDIT-mediated repression during sporulation.

Paediatric HIV infection.

HIV infection in children is a family disease, with social, economic and medical aspects that make it one of the most challenging diseases of our time. Knowledge about the factors involved in mother-to-child transmission and the natural history of the disease is gradually increasing although there is still much to understand. As the majority of children become infected through mother-to-child transmission, perinatally acquired infection will parallel increases in heterosexual transmission and the numbers of infected women of childbearing age. Current estimates of the rate of vertical transmission range from 14% to 39% in different studies. The relative proportion of transmission occurring in utero, peripartum or postpartum may vary in different localities and remains unclear. A study recently carried out in the USA showed that zidovudine given late in pregnancy, peripartum and in the neonatal period decreases HIV transmission from 25% to 8%. The clinical presentation of HIV infection in children depends in part on exposure to different infections. In developing countries the children usually present with nonspecific signs and symptoms, such as failure to thrive, chronic diarrhoea, cough and recurrent bacterial infections. Other common presentations include generalized lymphadenopathy, oropharyngeal candidiasis, dermatitis, enlargement of parotid glands and neurological problems, including delayed development.

PIP: Since the majority of children with HIV are infected through vertical transmission, perinatally acquired infection parallels increases in heterosexual HIV transmission and the numbers of seropositive women of childbearing age. Various studies have estimated the rate of vertical transmission at 14-39%, but the relative proportion of transmission occurring in utero, peripartum, and postpartum remains unclear. Zidovudine administration in late pregnancy, peripartum, and the neonatal period has been shown, in the US, to reduce HIV transmission from 25% to 8%. In developing countries, HIV-infected children generally present with nonspecific signs and symptoms such as failure to thrive, chronic diarrhea, cough, and recurrent bacterial infections. Other common presentations include generalized lymphadenopathy, oropharyngeal candidiasis, dermatitis, enlargement of parotid glands, and neurological problems such as delayed development. The World Health Organization has delineated guidelines for recognizing pediatric HIV infection in developing countries where HIV testing is unavailable or unaffordable. These guidelines encompass cardinal, characteristic, and associated findings in combination with epidemiologic risk factors. The prognosis of pediatric AIDS depends on factors such as age of presentation, severity of AIDS diagnosis, and the availability of health care and drugs to treat opportunistic infections.

Assessment of HIV/AIDS knowledge, attitudes and behaviour of high school students in Papua New Guinea.

OBJECTIVE: To assess the knowledge, attitudes and behaviour of high school students (grade 10) with regard to HIV infection and AIDS. METHODS: A self-administered questionnaire survey was carried out in 21 high schools in 6 different provinces. The questionnaire was anonymous and contained questions about HIV transmission, preventive measures, attitudes towards HIV infection and a few questions about personal sexual behaviour. PRELIMINARY RESULTS: A total of 1811 students completed the questionnaire. 46% were female. The average age was 17 years. Over 98% knew what AIDS and HIV were. 97% knew that HIV was sexually transmitted, but many misconceptions existed: one-third thought that HIV was transmitted by mosquitoes, 7% that HIV-infected persons were a danger in the classroom. 72% knew that using a condom at every sexual encounter was a way of protection from HIV infection. Approximately 25% reported to have had sexual contacts, and of 15-year-old students 14% were sexually active. Although STD/AIDS education is part of the curriculum for grade 8 the principals of the majority of the schools reported that no formal teaching was done. DISCUSSION: Although the majority of students knew that HIV is sexually transmitted, basic knowledge about STDs is lacking and is not taught as part of the curriculum in most of the schools. Teaching about STDs and HIV needs to be enforced and safe sexual practices need to be discussed with the students.

Recombinant hirudin as a periprocedural antithrombotic in coronary angioplasty for unstable angina pectoris.

Percutaneous transluminal coronary angioplasty is often complicated by thrombotic abrupt vessel closure in patients with unstable angina pectoris. The present multicentre trial was performed to determine the feasibility of two-dose regimens of recombinant hirudin (r-hirudin) compared to standard heparin in patients undergoing coronary angioplasty for unstable angina, and to investigate the effects of the different treatment regimen on markers of coagulation activation. At five participating centres, 61 patients were randomly enrolled in one of two sequential groups of r-hirudin (group 1: 0.3 mg.kg-1 i.v. bolus, 0.12 mg.kg-1.h-1 i.v. infusion; 21 patients; group 2: 0.5 mg.kg-1 i.v. bolus, 0.24 mg.kg-1.h-1 i.v. infusion; 19 patients) or in a heparin control group (150 IU.kg-1 i.v. bolus, 20 IU.kg-1.h-1 i.v. infusion; 21 patients). Antithrombotic therapy was started immediately before coronary angioplasty and continued for 24 h. This was followed by a low-dose anticoagulant infusion for another 24 h (r-hirudin: 0.04 mg . kg-1 . h-1; heparin: 7 IU . kg-1 . h-1). Activated partial thromboplastin time, r-hirudin plasma concentrations by both immunological and functional assay, thrombin-hirudin complex, thrombin-antithrombin III complex, soluble fibrin, and prothrombin fragment 1 + 2 were closely monitored. The median partial thromboplastin time prolongations at 24 h vs baseline were found to be 1.9-fold and 2.3-fold in r-hirudin group 1 and dose group 2, respectively, and 3.0-fold in the heparin group. There was a dose-dependent correlation between partial thromboplastin time and the r-hirudin plasma levels (r = 0.61). In five of 21 patients of dose group 1, three of 19 patients of dose group 2, and 10/21 patients of the heparin group, partial thromboplastin time values exceeding the predefined target range prompted an interruption of the infusion. One major bleeding complication occurred in dose group 2. The functional assay for the estimation of r-hirudin plasma concentrations showed excellent correlations to the immunological technique (r = 0.99). Differences between the thrombin-hirudin complex levels could not be observed. Increased concentrations of thrombin-antithrombin III complex, soluble fibrin, and prothrombin fragment 1 + 2 were seen 4-8 h after coronary angioplasty and after reduction of the high-dose therapy in dose group 1 when compared with dose group 2 and the heparin group, respectively. Based on coagulation tests the present study showed the feasibility of a periprocedural antithrombotic regimen with r-hirudin for patients undergoing coronary angioplasty for unstable angina. In addition to the partial thromboplastin time the determination of r-hirudin plasma levels by a chromogenic substrate assay considerably improves the monitoring of therapy. The lower dose r-hirudin regimen seems to be suboptimal as periprocedural anticoagulation in coronary angioplasty patients as indicated by markers of thrombin generation and thrombin activity.