The first 2 case reports of frozen embryo donation twin pregnancies in Singapore: hormonal profiles and obstetrical outcome

A 35 year old women with premature ovarian failure and another 30 year old women with gonadal dysgenesis were the recipients of donated supernumerous frozen embryos after successfully prepared with cyclic steroid replacement therapy as described previously. One patient received 4 and the second 2 frozen embryos, transferred transcervically on the 3rd day of progesterone administration. Both patients had viable twin pregnancies. The plasma beta hCG levels for both patients at 2 weeks post replacement (4 weeks gestation) were lower than the median values in our normal, uncomplicated singleton pregnancy for the same gestation. The level after 4 weeks post-replacement (6 weeks gestation) became comparable. Plasma progesterone profiles suggested a level of above 70 ng/ml would be enough to support the twin pregnancies. The first patient developed antepartum haemorrhage of unknown origin at 34 weeks of gestation preceding preterm premature rupture of membranes and subsequently had preterm labour. The second patient developed proteinuric hypertension at 33 weeks of gestation. Both ended in a lower segment cesarean section. Both sets of twins and their mothers were discharged well.

The electron-dose distribution surrounding an 192Ir wire brachytherapy source investigated using EGS4 simulations and GafChromic film

The steep dose gradient around 192Ir brachytherapy wire implants is predicted by the EGS4 (PRESTA version) Monte Carlo simulation. When considering radiation absorbing regions close to the wire source, the accurate dose distribution cannot be calculated by the GE Target II Sun Sparc treatment-planning system. Experiments using GafChromic film have been performed to prove the validity of the EGS4 user code when calculating the dose close to the wire source in a low energy range.

Midline extraperitoneal approach for elective abdominal aortic aneurysm repair

The incidence of abdominal aortic aneurysms (AAA) is rising and elective repair is becoming more commonplace. We describe a new, simple midline extraperitoneal approach for AAA repair. It is particularly suitable for patients who have an inflammatory AAA, abdominal adhesions or a horseshoe kidney. This approach provides excellent exposure to the whole aortoiliac system without the need for separate incisions, whilst retaining the potential advantages of the extraperitoneal approach.

Identification and diurnal studies of pineal and serum 5-methoxytryptamine in the rat and quail

Picomole to femtomole per gland/ml levels of 5-methoxytryptamine (5MT) in the pineal gland and serum of the rat and quail were determined, in the absence of a monoamine oxidase inhibitor, by using the ultra-sensitive technique of capillary column gas chromatography/electron-capture negative ion chemical ionization mass spectrometry. Diurnal rhythms of pineal 5MT with high levels at mid-light and low levels at mid-dark were found in both species, while serum 5MT levels showed less or no diurnal variations. The definitive presence of 5MT in the pineal gland and blood circulation provides further evidence that it is potentially a neurohormone. Whether 5MT is implicated in the photoperiodic responses and/or other physiological functions of animals, however, remains to be investigated.

Multiple interactions stabilize a single paused transcription intermediate in which hairpin to 3' end spacing distinguishes pause and termination pathways

Transcription is delayed in the leader regions of the Escherichia coli trp and his operons by multipartite pause signals that consist of four components: a nascent RNA structure (the pause hairpin), the 10 or 11 nt 3'-proximal region between the pause hairpin and the RNA 3' end, the bases in the active site, and approximately 14 bp of duplex DNA downstream from the pause site. Results described in the accompanying paper suggest that the his pause hairpin slows nucleotide addition via interaction with an easily disordered surface on RNA polymerase. Here we report that the four pause signal components slow nucleotide addition in a single kinetic intermediate. Formation of the paused transcription complex, in contrast, involves synergistic effects of RNA and DNA sequences that select the wild-type pause site from among several adjacent possibilities. Extending the pause hairpin with one G x C base-pair reduces pausing, apparently by interfering with pause hairpin interaction; adding a second C x G base-pair that reduces the 3'-proximal RNA to 9 nt or less (within the 7 to 9 nt characteristic of rho-independent terminators) induces transcript release. We propose that escape from the pause is governed by a rate-limiting isomerization that may require substrate NTP binding to re-establish the active site geometry, whereas transcript release and termination ensue when the hairpin interaction is weakened and isomerization to an active conformation is blocked.

Effects of neutral salts on RNA chain elongation and pausing by Escherichia coli RNA polymerase

We examined the effects of neutral salts and the non-ionic solute 2-methyl,-2,4-pentanediol (MPD) on transcript elongation by Escherichia coli RNA polymerase and on pausing induced by the multipartite his leader pause signal. All solutes tested slowed the overall rate of elongation, with anions showing the dominant effects in the order: (most inhibitory) HPO4(2-) > OAc- > SO4(2-) > ClO4- > I- approximately NO3- > Br approximately Cl- approximately MPD (least inhibitory). Although the protein structure-stabilizing anions HPO4(2-), OAc-, and SO4(2-) also increased the pause half-life at the his leader pause site, the remaining solutes accelerated escape from pause site in the order: (greatest acceleration) NO3- > ClO4- > I- > Br- > Cl- > MPD (least acceleration). Cl(-)-induced acceleration of escape from the pause site also occurred on mutant templates altered for the 3'-proximal region, RNA 3' end, or downstream DNA. The effect was eliminated, however, by base substitutions that destabilize the pause RNA hairpin or that extend it toward the 3' end. This "perfect hairpin" itself reduced the pause half-life by a factor of 3. We suggest that the pause RNA hairpin stabilizes a paused conformation of the transcription complex through an interaction with an easily disordered region of RNA polymerase. Extending the stem of the pause hairpin may disrupt the interaction by altering the position of the hairpin in the transcription complex. Anions may either compete for the interaction directly or disorder the site of hairpin interaction by chaotropic effects. We suggest that the negative effect of structure-stabilizing anions like OAc- and SO4(2-) may reflect passage of RNA polymerase through significantly different conformations during rapid elongation, some of which may expose hydrophobic surface.

The dose distribution close to an 192Ir wire source: EGS4 Monte Carlo calculations

A Monte Carlo simulation using the PRESTA version of the EGS4 code has been employed as an investigative tool to calculate the absorbed dose in water close to 192Ir wire implants. It has been shown that a treatment planning system, such as GE Target II, using the Sievert integral and the Meisberger polynomial is only able to reproduce the Monte Carlo results at radial distance of 1 mm and farther away. The Sievert integral used with the Meisberger polynomial is proven to be in good agreement with the Monte Carlo generated data at distances between 1 mm and 1 cm.

Chronic low-dose follicle-stimulating hormone compared with clomiphene/human menopausal gonadotropin for induction of ovulation

Concurrent administration of clomiphene can reduce the amount of gonadotropins required for induction of ovulation. Recently, follicle-stimulating hormone (FSH) administered in a chronic, low-dose fashion has been reported to give satisfactory pregnancy rates. We compared the conventional clomiphene/human menopausal gonadotropin (hMG) with the chronic, low-dose FSH regimen for induction of ovulation in 87 patients over 110 cycles. The clomiphene/hMG regimen required half the amount of gonadotropin compared to the chronic FSH regimen to achieve follicular maturation. Despite the reduced amount of gonadotropin, the clomiphene/hMG regimen induced a mean fourfold higher level of estradiol production and was associated with significantly greater numbers of large and intermediate-sized follicles compared to the chronic FSH regimen. The proportion of clomiphene/hMG cases with multifollicular development and overstimulation was therefore high (30%). In contrast, the chronic FSH regimen, despite requiring larger amounts of gonadotropin and longer periods of treatment, resulted in unifollicular development, low rates of overstimulation and improved pregnancy rates. We conclude that although clomiphene can reduce the requirement for gonadotropins, the relative safety and effectiveness of the chronic low-dose FSH regimen makes it the method of choice for ovulation induction.

The first frozen embryo donation pregnancy for hypergonadotrophic hypogonadism in Singapore--hormonal profile and obstetric outcome

This is the first report in South East Asia of a singleton frozen embryo donation pregnancy for hypergonadotrophic hypogonadism. The hormonal profile was compared with that of a control group of normal uncomplicated singleton pregnancies in Singapore. The plasma beta hCG levels were lower compared to those of our normal uncomplicated singleton pregnancies at 2 to 3 weeks after the embryo transfer but became comparable at 4 to 5 weeks after embryo transfer. The successful vaginal delivery and the obstetric complications developed in this case are discussed.

Sigma domain structure: one down, one to go

The recent publication of the 2.6 A crystal structure of a portion of sigma70 provides insight into the role of sigma during transcription initiation. This high resolution picture unveils novel questions.

Analysis of 5-methoxytryptamine at the femtomole level in the rat and quail brain by gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry

A sensitive method for the measurement of endogenous 5-methoxytryptamine in brain tissue has been developed using capillary column gas chromatography-electron-capture negative-ion chemical ionization mass spectrometry. 5-Methoxytryptamine was first converted to N-[2H3]acetyl-5-methoxytryptamine by reaction with hexa-deuterated acetic anhydride, followed by reaction with pentafluoropropionic anhydride to yield the highly electron-capturing 3,3'-spirocyclic pentafluoro-propionyl indolenine derivative. Quantitative analysis was carried out by selected-ion monitoring of the [M-HF].- and [M-HF-DF].- ion intensity of the 3.3'-spirocyclic pentafluoropropionyl indolenine derivative, using 5-methoxy-[alpha, alpha, beta, beta-2H4]tryptamine as the internal standard. The presence of 5-methoxytryptamine in the brain tissue was demonstrated. In the absence of a monoamine oxidase inhibitor, the mean +/- S.D. levels of 5-methoxytryptamine in the rat and quail whole brain were found to be 30 +/- 6 and 347 +/- 52 pg/g, respectively. The possible physiological functions of 5-methoxytryptamine as a neuromodulator and/or neurotransmitter have to be considered.

A structure/function analysis of Escherichia coli RNA polymerase

Control of RNA polymerase is a common means of regulating gene expression. A detailed picture of both the structure and how the structural details of RNA polymerase encode function is a key to understanding the molecular strategies used to regulate RNA polymerase. We review here data which ascribes functions to some regions of the primary sequence of the subunits (alpha, beta beta' sigma) which make up E. coli RNA polymerase. We review both genetic and biochemical data which place regions of the primary sequence that are distant from one another in close proximity in the tertiary structure. Finally we discuss the implications of these findings on the quaternary structure of RNA polymerase.

Obesity and quality of life after primary hip arthroplasty

In a prospective trial we studied 176 consecutive patients having a primary total hip arthroplasty to compare the quality of life before and after operation in non-obese and obese groups. We used a modified Harris hip score and the Rosser Index Matrix to generate these scores, and found that the median preoperative quality of life score for both groups was similar. During review, both groups showed a corresponding marked improvement in quality of life scores at one and three years. There was no statistically significant difference in the improvement in scores between the non-obese and obese groups. It appears that relative body-weight on its own does not influence the benefit derived from primary total hip arthroplasty.

A comparison of two photon planning algorithms for 8 MV and 25 MV X-ray beams in lung

We report results of a comparison of two photon planning algorithms, the Clarkson Scatter Integration algorithm and the Equivalent Tissue-air Ratio algorithm, using a simple lung phantom for 8 MV and 25 MV X-ray beams of field sizes 5 cm x 5cm and 10 cm x 10 cm. Central axis depth-dose distributions were measured with a thimble chamber or a Markus parallel-plate chamber. Dose profile distributions were measured with TLD rods and films. Measured dose distributions were then compared to predicted dose distributions. Both agorithms overestimate the dose at mid-lung as they do not account for the effect of electronic disequilibrium. The Clarkson algorithm consistently shows less accurate results in comparison with the ETAR algorithm. There is additional error in the case of the Clarkson algorithm because of the assumption of a unit density medium in calculating scatter, which gives an overestimate in the effective scatter-air ratios in lung. For a 5 cm x 5 cm field, the error of dose prediction (Dpredicted-Dmeasured) for 25 MV x-ray beam at mid-lung is 15.8% and 12.8% for Clarkson and ETAR algorithm respectively. At 8 MV the error is 9.3% and 5.1% respectively. In addition, both algorithms underestimate the penumbral width at mid-lung as they do not account for the penumbral flaring effect in low density medium. It is very important for medical physicists, radiation therapists and clinicians to be aware of the limitation of their radiotherapy treatment planning systems.

Discontinuous movements of DNA and RNA in RNA polymerase accompany formation of a paused transcription complex

A central enigma of transcriptional regulation is how the normally efficient transcription elongation complex stops at pause and termination signals. One possibility, raised by the discovery that RNA polymerase sometimes contracts its DNA footprint, is that discontinuous movements contribute to recognizing these signals. We report that E. coli RNA polymerase responds to sequences immediately downstream and upstream from the his leader pause site by changing neither its downstream DNA contact nor its upstream RNA contact for 8 bp preceding the pause. This compressed complex isomerizes to a paused conformation by an approximately 10 bp jump of its downstream DNA contact and simultaneous extrusion of an RNA hairpin that stabilizes the paused conformation. We suggest pausing and termination could be alternative outcomes of a similar isomerization that depend on the strength of contacts to 3'-proximal RNA remaining after the jump.

The desire for multiple births in couples with infertility problems contradicts present practice patterns

Paradoxically, the attitude of infertility patients towards multiple births has never been investigated. We therefore generated a survey by questionnaire, which was sent to 3800 consecutive unselected couples with infertility problems: 582 responses were received (15% response rate) and analysed. The percentage distribution of the responses to 21 questions, addressing attitudes towards and knowledge about the risk of multiple gestations, was the main outcome. Worry about multiple births was expressed, independent of the number of multiples, although fear about multiple conceptions was rejected by a large majority (64%). The risk of a twin birth was not strongly perceived, but the perception of risk increased with increasing numbers of multiples: triplets (50-62%), quadruplets or more (71-72%). A desire for the conception of twins was expressed by 67-90% of couples, a desire for the conception of triplets was equally expressed and rejected, and for a multiple gestation beyond triplets was rejected by 73-82% of couples. Patients were educated about the risks of selective embryo reduction and responded in a bimodal fashion to the option of utilizing this procedure, with equal numbers being willing to consider or reject it. Age, parity and length of infertility did not affect the couples' worry or fear about multiples. The desire for twins and triples, however, was correlated significantly with age (twins, P = 0.032; triplets, P = 0.03); there was no such correlation for larger multiples. The length of infertility was correlated with a positive attitude towards multiples beyond triplets (P = 0.029) but was not correlated with a desire for twins or triplets. Prior parity did not affect the attitude towards multiples at all.(ABSTRACT TRUNCATED AT 250 WORDS)

Potential use of the intercostal artery as an in situ graft: a cadaveric study

The third to eighth intercostal arteries (ICAs) were bilaterally dissected in 10 cadavers to assess their length and possible routes to coronary arteries if used as in situ grafts. The mean lengths for the intercostal arteries harvested were 27.0 +/- 2.9 cm on the left and 27.4 +/- 3.2 cm on the right. The shortest anatomic route to the coronary arteries of the in situ ICAs harvested was medial to the lung and either superior to or inferior to the hilum. By using either the superior or inferior routes in situ ICAs were long enough to reach the major coronary artery territories in all cadavers. The most suitable ICAs for grafting the coronary arteries and the shortest routes were as follows: left anterior descending--left fifth ICA by inferior route; circumflex coronary artery-left fifth ICA by inferior route; and right coronary artery-right seventh ICA by inferior route. We conclude that it is anatomically feasible to use the intercostal artery as an in situ graft in coronary artery operation.

Iterative maximum likelihood displacement field estimation in quantum-limited image sequences

We develop an algorithm for obtaining the maximum likelihood (ML) estimate of the displacement vector field (DVP) from two consecutive image frames of an image sequence acquired under quantum-limited conditions. The estimation of the DVF has applications in temporal filtering, object tracking, stereo matching, and frame registration in low-light level image sequences as well as low-dose clinical X-ray image sequences. In the latter case, a controlled X-ray dosage reduction may be utilized to lower the radiation exposure to the patient and the medical staff. The quantum-limited effect is modeled as an undesirable, Poisson-distributed, signal-dependent noise artifact. A Fisher-Bayesian formulation is used to estimate the DVF and a block component search algorithm is employed in obtaining the solution. Several experiments involving a phantom sequence and a teleconferencing image sequence with realistic motion demonstrate the effectiveness of this estimator in obtaining the DVF under severe quantum noise conditions (20-25 events/pixel).

GreA-induced transcript cleavage in transcription complexes containing Escherichia coli RNA polymerase is controlled by multiple factors, including nascent transcript location and structure

The Escherichia coli GreA and GreB proteins induce cleavage of 3' fragments from nascent transcripts in halted transcription complexes. We have overproduced and purified the GreA protein and tested how it affects initiation, pausing, and termination by E. coli RNA polymerase. Recombinant GreA induced cleavage of two to three nucleotide fragments in two promoter-proximal complexes, whereas an apparently endogenous cleavage removed a single larger fragment. Both types of cleavage stopped once the transcript was shortened to approximately 10 nucleotides. However, during initiation, GreA induced cleavage of transcripts as short as four nucleotides, inhibiting their release as abortive products and stimulating both productive initiation and "primer-shifting" at a weak promoter. GreA induced repetitive cleavage over a long distance in complexes containing a long G-less nascent transcript. However, reverse translocation was inhibited in transcription complexes that contained a G-rich, C-less nascent transcript. Substituting IMP for GMP in the transcript relieved inhibition. Finally, GreA had little effect on transcription through the his and trp leader pause sites or on termination at nine different p-independent terminators. We propose that transcript cleavage and reverse translocation are controlled in part by backsliding of the nascent transcript through an RNA-binding site.

Analytical solutions of Pennes bio-heat transfer equation with a blood vessel

The heat transfer within a perfused tissue in the presence of a vessel is considered. The bio-heat transfer equation is used for the perfused tissue and a lumped capacitance analysis is used for the convection in the vessel with a constant Nusselt number. Analytical solutions are obtained for two cases: (i) the arterial temperature of the perfused blood in the bio-heat transfer equation is equal to the axially varying mixed mean temperature of the blood in the vessel and, (ii) that arterial temperature is assumed to be constant. Dimensionless equilibrium length and temperature expressions are obtained and presented.

The intracellular tyrosine kinase domain of the epidermal growth factor receptor undergoes a conformational change upon autophosphorylation

The intracellular portion of the epidermal growth factor receptor consists of a tyrosine kinase domain of approximately 290 amino acids and a COOH-terminal regulatory domain of approximately 230 amino acids that contains five sites of autophosphorylation. The effect of autophosphorylation on the conformation of the intracellular domain has been analyzed using gel filtration. Both phosphorylated and dephosphorylated forms of the intracellular domain exist as monomers and as dimers and appear to have an extended conformation. The Stokes' radii of phosphorylated monomers and dimers were larger than those of the dephosphorylated forms, indicating that the dephosphorylated form is more compact. These results indicate that a significant conformational change occurs in the intracellular portion of the epidermal growth factor receptor upon tyrosine autophosphorylation.

Low bit rate video coding using robust motion vector regeneration in the decoder

In this paper, we present a novel coding technique that makes use of the nonstationary characteristics of an image sequence displacement field to estimate and encode motion information. We utilize an MPEG style codec in which the anchor frames in a sequence are encoded with a hybrid approach using quadtree, DCT, and wavelet-based coding techniques. A quadtree structured approach is also utilized for the interframe information. The main objective of the overall design is to demonstrate the coding potential of a newly developed motion estimator called the coupled linearized MAP (CLMAP) estimator. This estimator can be used as a means for producing motion vectors that may be regenerated at the decoder with a coarsely quantized error term created in the encoder. The motion estimator generates highly accurate motion estimates from this coarsely quantized data. This permits the elimination of a separately coded displaced frame difference (DFD) and coded motion vectors. For low bit rate applications, this is especially important because the overhead associated with the transmission of motion vectors may become prohibitive. We exploit both the advantages of the nonstationary motion estimator and the effective compression of the anchor frame coder to improve the visual quality of reconstructed QCIF format color image sequences at low bit rates. Comparisons are made with other video coding methods, including the H.261 and MPEG standards and a pel-recursive-based codec.