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At least 487 records · Page 27Linked to original sources
PubMed2003

Triplet pregnancy after oocyte donation in women 46 years of age and older: three case reports.

PURPOSE: Presentation of three triplet pregnancies achieved in women 46 years of age and older with the use of donated oocytes. MATERIAL & METHODS: Two healthy perimenopausal women 46 and 48 years old and one healthy menopausal woman 48 years old, requesting fertility options. All of them followed oocyte donation programs resulting in triplet pregnancy. Maternal as well as perinatal complications, mode of delivery and birth weight are reported. RESULTS: Three triplet pregnancies were achieved using donated oocytes. Prenatal diagnosis was reassuring. Preterm rupture of membranes, preterm labor and gestational diabetes complicated the pregnancies. Cesarean section was the mode of delivery for all the cases giving birth to nine healthy neonates weighing between 1,130 and 2,450 g. No postpartum complications were encountered. CONCLUSIONS: Triplet pregnancies achieved with the use of donated oocytes at a very advanced maternal age represent high-risk obstetrical cases. Cautious prenatal evaluation of maternal health and intensive antenatal surveillance are imperative principles allowing the most favorable outcome of these pregnancies.

Cesarean Section↗
PubMed2004

Risks in triplet pregnancy: advanced maternal age, premature rupture of membranes and risk estimates of mortality.

OBJECTIVE: To investigate the impact of older maternal age on the risk of mortality associated with premature rupture of membranes (PROM) among triplets. STUDY DESIGN: A retrospective, cohort study was performed on triplet deliveries in the United States that occurred in the period perinatal and 1995-1998. The study group comprised mothers aged > or =40 years (older mothers), who were compared to mothers aged 30-39 (mature mothers), 20-29 (younger mothers) and mothers <20 (teenagers). We computed risks of mortality associated with PROM within each maternal age category using generalized estimating equations to take into account both intracluster and intercluster sources of variation. RESULTS: The risk of stillbirth and of neonatal and perinatal mortality related to PROM was highest among teenagers. In all circumstances, the risk of both intrauterine and extrauterine death resulting from PROM diminished progressively with increasing maternal age until age 40 and beyond, at which point the risk rose once more and produced a U shape. PROM triplets of older mothers had apparently higher mortality indices than did those of younger and mature mothers, although the risk difference did not show statistical significance for any of the mortality indices. Similarly, the proportion of preventable deaths if PROM could be averted demonstrated a U-shape, consistent with that of risk estimates. CONCLUSION: Premature rupture of membranes was associated with an increase risk of perinatal and infant mortality among triplets. Although older mothers demonstrated higher risk levels for all mortality indices in comparison to younger and mature mothers, our findings did not reach statistical significance.

Adolescent↗
PubMed2005

[The adaptation experience in a case of family stress generated by the birth of premature triplets].

The purpose of this study was to examine the adaptation of a family whose parturient mother had given birth of premature triplets following artificial insemination. The researcher came into contacted with the family at the pediatric outpatient service and provided care immediately. Data were collected by participant observations and interviews. There were nine home visits and three telephone interviews performed in the period from March 6th to June 10th, 2002. Records of proceedings were written up after every interview; the records were analyzed and classified systematically. From the data, four themes of family stress adaptation emerged: Ensuring and facilitating the healthy development of the children, reconstructing the effective resources of the family, wishing for affirmation of the premature triplets by relatives, reconsidering the future of the family. The results of this study may enhance nurses' understanding of the adaptation of families to stress generated by premature triplets. Nurses may apply family centered maternity care to deal with such cases. The families concerned will then be able to raise their confidence about welcoming and caring for premature triplets.

Adaptation, Psychological↗
PubMed2006

[Comparison between computerized cardiotocography analysis in triplet and singleton pregnancies].

OBJECTIVES: Triplet pregnancies have higher perinatal morbidity and mortality rates than singleton pregnancies. In modern perinatology computer cardiotocography is one of the best methods of fetus state assessment. DESIGN: The research was based on computer analysis of cardiotocograph printouts. MATERIALS AND METHODS: The studies were made on 39 pregnant women in 27-36 week of gestation. The women were hospitalized in the Clinic of Perinatology I Department of Gynecology and Obstetrics, Medical University of Lodz and divided into two groups. First consisted of 30 singleton, second of 9 triplet pregnancies. RESULTS: Computer analysis of cardiotocograph printouts was performed and compared between the triplet and singleton pregnancy groups and presented in forms of tables. CONCLUSIONS: In the studded group of triplet pregnancy statistically significant higher number of high episodes, accelerations, fetal movements and signal loss were observed. The Apgar score and arterial cord pH was not different between the both groups.

Cardiotocography↗
PubMed1990

Sonographic growth measurements in triplet pregnancies.

Sonographic growth curves of biparietal diameter (BPD), head circumference, abdominal circumference, head circumference/abdominal circumference ratio, and femur length were generated from 24 uncomplicated, concordant triplet pregnancies. These were compared with the standard curves derived for singletons used in our medical center. Slowing of BPD, head circumference, and abdominal circumference growth was noted in triplets from the 28th week of gestation, whereas the head circumference/abdominal circumference ratio was similar to that of singletons. Femur growth was parallel to that of singletons, although on the low margin of the two standard deviations. We conclude that the growth patterns of triplets are different from those of singletons. We suggest that femur length derived for singletons may be suitable for the follow-up of triplets. However, when growth retardation is suspected, the growth curves presented herein may be used to identify the growth-retarded fetus.

Abdomen↗
PubMed1987

Prolonged delivery-abortion interval in twin and triplet pregnancies. A report of two cases.

Two cases occurred of a delayed interval between the second-trimester delivery and abortion of a nonviable fetus from a multifetal gestation with a surviving fetus or fetuses. In twin pregnancy, there was a 23-day interval between the delivery of twin A (at 21 weeks) and of twin B (at 24 weeks). In a clomiphene-induced triplet pregnancy there was a 74-day interval between the spontaneous abortion of triplet A at 17 weeks and of triplets B and C at 27 weeks. This is the second reported case of two surviving infants after a delayed abortion-delivery interval in a triplet pregnancy in a single uterus.

Adult↗
PubMed1986

Biochemical differences related to birth order in triplets.

This is the first report to date on biochemical parameters in triplets. Umbilical artery and venous pH, PO2, PCO2, lactate and base deficit were measured in seven sets of triplets. Other parameters compared were route of delivery, one- and five-minute Apgar score, birth weight, relative birth order and sex. Twenty-one viable infants were born from three induced and four spontaneous pregnancies. Female: male sex ratio was 1.6:1.0. All triplets within a set were delivered by the same route--six sets by cesarean section and one set vaginally. There were no significant differences, according to Student's t-test, in birth weight, Apgar scores and biochemical parameters related to birth order. Comparison of umbilical artery and umbilical venous pH, PO2, PCO2, lactate and base deficit differences did not demonstrate evidence of acidosis or significant base deficit in the third triplet when compared with the first two, suggesting that the duration in utero after deliver of the firstborn is not associated with metabolic acidosis or hypoxia in the absence of any obstetric complication or anesthetic problem.

Apgar Score↗
PubMed1995

Quantitative variation in sets of triplets and quadruplets: a simulation.

A computer simulation was devised to generate realistic but large samples of twins, triplets, and quadruplets in each of the possible zygosity types. To validate the simulation, I used formulas proposed by Richter and Geisser (1960) to predict the mean value of the sum of squared deviations in each of three types of triplets and five types of quadruplets and to predict the distributions of the sums of squares in pure types (e.g., monozygotic and trizygotic triplets). Use of the formulas to predict distributions in sets of mixed type or to diagnose zygosity requires more advanced mathematical methods, but the simulation readily generates standard populations of all types of sets. If large enough numbers of real triplets or quadruplets ever become available to permit useful comparison with these standards or with the formulas, developmental peculiarities of the higher-order births might be revealed.

Computer Simulation↗
PubMed1993

A review of triplet pregnancy.

Nineteen sets of triplets were delivered in the National Maternity Hospital between January 1st 1980 and December 31st 1990 inclusive. Thirteen triplet pregnancies resulted from spontaneous ovulation and six from ovulation induction therapy for infertility. Management was conservative. Bed rest and home monitoring were not advised routinely and cervical cerclage and tocolytic agents were not used. Ten of the patients were delivered by caesarean section. The prematurity rate was 79% and five sets of triplets were delivered before 32 weeks gestation. The perinatal mortality rate was 35/1000. This reflects a general improvement in the obstetric and neonatal care of triplet pregnancy over the past decade.

Adult↗
PubMed1998

Perinatal outcome associated with outpatient management of triplet pregnancy.

OBJECTIVE: Our goal was to compare the lengths of hospitalization and the perinatal outcomes of triplet pregnancies managed with either outpatient or inpatient third-trimester bed rest. STUDY DESIGN: Thirty-two triplet pregnancies in which outpatient bed rest was prescribed (April 1993 to April 1996) were compared with a historic cohort of 34 triplets (January 1985 to March 1993) in which routine hospitalization was undertaken in the third trimester. Length of hospitalization and maternal and neonatal outcome parameters were compared between groups. RESULTS: Maternal inpatient hospital days were significantly reduced for the group managed as outpatients, but combined maternal and neonatal hospitalization was similar between groups. The mean gestational age at delivery was 1 week greater in the hospitalized cohort (33.5+/-2.8 vs 32.5+/-2.8, respectively; p=0.16), and average birth weight was correspondingly greater in hospitalized cases (1942 gm vs 1718 gm, p < 0.005). Neonatal lengths of stay were similar between groups, reflecting earlier postnatal discharge in the outpatient era of this study. Preeclampsia occurred with greater frequency in the outpatient group (31.3% vs 8.8%, p=0.02), and the neonatal complication of intraventricular hemorrhage occurred more commonly in this cohort as well (10/96 vs 1/102, p=0.004). All other maternal and neonatal complications were similar between groups. CONCLUSION: Reduction in the length of hospitalization attributable to outpatient management was limited to the maternal length of stay. It is possible that the observed maternal and neonatal complications in the outpatient group may have been related to less rigorous bed rest. We would suggest that the differences noted in preeclampsia, birth weight, and intraventricular hemorrhage support prospective evaluation of bed rest in triplet pregnancy.

Adult↗
PubMed2000

Very late-onset Friedreich ataxia despite large GAA triplet repeat expansions.

BACKGROUND: Most patients with Friedreich ataxia (FRDA) have abnormal GAA triplet repeat expansions in both X25 genes. The size of the GAA expansion in the shorter of the 2 expanded alleles correlates significantly with parameters of clinical severity and is inversely related to the age at onset. OBJECTIVES: To describe the clinical and molecular genetic findings in a patient with very late-onset FRDA and to review the literature. PATIENT AND METHODS: A 58-year-old white woman with mild progressive gait disturbance of 15 years' duration whose examination revealed mild incoordination was analyzed for mutations in the X25 gene. A combination of long-range polymerase chain reaction and genomic Southern blot analyses were used to identify GAA expansions in intron 1 of the X25 gene. To uncover evidence of somatic variability in triplet repeat length, DNA isolated from several tissue samples was similarly analyzed. Single-strand conformational polymorphism analysis was used to screen for mutations spanning the entire coding sequence of frataxin and all intron-exon junctions of the X25 gene. RESULTS: DNA isolated from blood leukocytes revealed GAA triplet repeat expansions in both X25 genes, which were estimated to contain 835 and 1200 repeats. Similar expansions were detected in DNA isolated from lymphoblasts, fibroblasts, buccal cells, and sural nerve, with estimated mean (+/- SD) lengths of the shorter and longer expansions being 854 (+/-69) and 1283 (+/-72) triplets, respectively. A review of reported cases of late-onset Friedreich ataxia (25-39 years) and very late-onset Friedreich ataxia (> or =40 years) demonstrated that this is the first instance of a patient presenting with very late-onset FRDA despite carrying more than 800 GAA repeats in both expanded X25 alleles. CONCLUSIONS: This unique case of very late-onset FRDA highlights a limitation in our ability to accurately predict the phenotype in FRDA based solely on the size of the GAA expansion. Other genetic or environmental factors may significantly modify disease severity in FRDA.

Age of Onset↗
PubMed2001

Theoretical characterization of photoisomerization channels of dimethylpyridines on the singlet and triplet potential energy surfaces.

Photoexcitations and photoisomerizations due to low-lying n pi* and pi pi* excited states of dimethylpyridines are investigated by density functional theory, CASSCF, CASPT2 and MRCI methodologies. Mechanistic details for the formation of Dewar dimethylpyridines and the interconversions of dimethylpyridines are rationalized through the characterization of minima and transition states on the singlet and triplet potential energy surfaces of relevant intermediates. Our present theoretical schemes suggest that Mobius dimethylpyridine intermediate 14 and azabenzvalene intermediate 10 can serve as possible precursors to Dewar dimethylpyridines and singlet phototransposition products, respectively. The calculations suggest that an S1(pi pi*)/S0 conical intersection in dimethylpyridines 2 is involved in the formation of 14. An azabenzvalene 10 might be formed through S2(pi pi*)/S1(n pi*) interaction followed by an S1/S0 decay in dimethylpyridine 6. Calculated barriers of isomerizations from 14 to Dewar dimethylpyridine 7 and from 10 to 4 are 8.4 and 28.5 kcal mol(-1) at the B3LYP/6-311 G** level, respectively. In the suggested triplet multistage transposition mechanism, an out-of-plane distorted geometry 19 due to vibrational relaxation of the T1(3B1) excited state of 3,5-dimethylpyridine 6 is a precursor of the interconversion of 6 to 2.4-dimethylpyridine 4. The formation of a triplet azaprefulvene 21 with a barrier of 20.7 kcal mol(-1) is a key step during the triplet migration process leading to another out-of-plane distorted structure 27. Subsequent rearomatization of 27 completes the interconversion of 6 with 4. Present calculations provide some insight into the photochemistry of dimethylpyridines at 254 nm.

Journal Article↗
PubMed2004

Friedreich ataxia in carriers of unstable borderline GAA triplet-repeat alleles.

Friedreich ataxia patients are homozygous for expanded GAA triplet-repeats containing 66 to 1,700 triplets. We report two patients with delayed-onset, hyperreflexia and gradually progressive disease. Both were heterozygous for large expansions and also carried alleles with 44 and 66 triplet-repeats, respectively. Due to somatic instability, 15% (GAA-44) and 75% (GAA-66) of cells contained alleles with >/=66 triplet-repeats, constituting a plausible mechanism for their mild phenotype. A sibling with a stable GAA-37 allele and a large expansion was clinically normal. Instability of borderline alleles confers a risk for Friedreich ataxia, and the range of pathogenic alleles is broader than previously recognized.

Alleles↗
PubMed2006

Pi topology and spin alignment in unique photoexcited triplet and quintet states arising from four unpaired electrons of an organic spin system.

Syntheses, electronic structures in the ground state, unique photoexcited states, and spin alignment are reported for novel biradical 1, which was designed as an ideal model compound to investigate photoinduced spin alignment in the excited state. Electron spin resonance (ESR), time-resolved ESR (TRESR), and laser-excitation pulsed ESR experiments were carried out. The magnetic properties were examined with a SQUID magnetometer. In the electronic ground state, two radical moieties interact very weakly (almost no interaction) with each other through the closed-shell diphenylanthracene spin coupler. On photoirradiation, a novel lowest photoexcited state with the intermediate spin (S = 1) arising from four unpaired electrons with low-lying quintet (S = 2) photoexcited state was detected. The unique triplet state has an interesting electronic structure, the D value of which is reduced by antiferromagnetic spin alignment between two radical spins through the excited triplet spin coupler. The general theoretical predictions of the spin alignment and the reduction of the fine-structure splitting of the triplet bis(radical) systems are presented. The fine-structure splitting of the unique photoexcited triplet state of 1, as well as the existence of the low-lying quintet state, is interpreted well on the basis of theoretical predictions. Details of the spin alignment in the photoexcited states are discussed.

Journal Article↗
PubMed2006

Spatial extent of the singlet and triplet excitons in luminescent angular-shaped transition-metal diynes and polyynes comprising non-pi-conjugated group 16 main group elements.

A novel approach based on conjugation interruption has been developed and is presented for a series of luminescent and thermally stable chalcogen-bridged platinum(II) polyyne polymers trans-[{-Pt(PBu3)2C[triple bond]C(C6H4)E(C6H4)C[triple bond]C-}n] (E = O, S, SO, SO2). Particular attention was focused on the photophysical properties of these Group 10 polymetallaynes and comparison was made to their binuclear model complexes trans-[Pt(Ph)(PEt3)2C[triple bond]C(C6H4)E(C6H4)C[triple bond]CPt(Ph)(PEt3)2] and their closest Group 11 gold(I) and Group 12 mercury(II) neighbours, [MC[triple bond]C(C6H4)E(C6H4)C[triple bond]CM] (M = Au(PPh3), HgMe; E = O, S, SO, SO2). The regiochemical structures of these angular-shaped molecules were studied by NMR spectroscopy and single-crystal X-ray structural analyses. Upon photoexcitation, each one has an intense purple-blue fluorescence emission near 400 nm in dilute fluid solutions at room temperature. Harvesting of the organic triplet emissions harnessed through the strong heavy-atom effects of Group 10-12 transition metals was studied in detail. These metal-containing aryleneethynylenes spaced by chalcogen units were found to have large optical gaps and high-energy triplet states. The influence of metal- and chalcogen-based conjugation interrupters on the intersystem crossing rate and on the spatial extent of the lowest singlet and triplet excitons was fully elucidated. We discuss and compare the phosphorescence spectra of these transition-metal diynes and polyynes in terms of the nature of the metal centre, conjugated chain length and Group 16 spacer unit. Our work here indicates that high-energy triplet states in these materials intrinsically give rise to very efficient phosphorescence with fast radiative decays and one could readily observe room-temperature phosphorescence for the platinum polyynes.

Journal Article↗
PubMed2005

Artificial photosynthetic reaction centers: mimicking sequential electron and triplet-energy transfer.

An artificial photosynthetic reaction center consisting of a carotenoid (C), a dimesitylporphyrin (P), and a bis(heptafluoropropyl)porphyrin (P(F)), C-P-P(F) , and the related triad in which the central porphyrin has been metalated to give C-P(Zn)-P(F) have been synthesized and characterized by transient spectroscopy. These triads are models for amphipathic triads having a carboxylate group attached to the P(F) moiety; they are designed to carry out redox processes across lipid bilayers. Triad C-P-P(F) undergoes rapid singlet-singlet energy transfer between the porphyrin moieties, so that their excited states are in equilibrium. In benzonitrile, photoinduced electron transfer from the first excited singlet state of P and hole transfer from the first excited singlet state of P(F) yield the initial charge-separated state C-P(.) (+)-P(F) (.) (-). Subsequent hole transfer to the carotenoid moiety generates the final charge-separated state C(.) (+)-P-P(F) (.) (-), which has a lifetime of 1.1 mus and is formed with a quantum yield of 0.24. In triad C-P(Zn)-P(F) energy transfer from the P(Zn) excited singlet to the P(F) moiety yields C-P(Zn)-(1)P(F) . A series of electron-transfer reactions analogous to those observed in C-P-P(F) generates C(.) (+)-P(Zn)-P(F) (.) (-), which has a lifetime of 750 ns and is formed with a quantum yield of 0.25. Flash photolysis experiments in liposomes containing an amphipathic version of C-P(Zn)-P(F) demonstrate that the added driving force for photoinduced electron transfer in the metalated triad is useful for promoting electron transfer in the low-dielectric environment of artificial biological membranes. In argon-saturated toluene solutions of C-P-P(F) and C-P(Zn)-P(F) , charge separation is not observed and a considerable yield of triplet species is generated upon excitation of the porphyrin moieties. In both triads triplet energy localized in the P(F) moiety is channeled to the carotenoid chromophore by a triplet energy-transfer relay mechanism. Certain photophysical characteristics of these triads, including the sequential electron transfer and the triplet energy-transfer relay mechanism, are reminiscent of those observed in natural reaction centers of photosynthetic bacteria.

Carotenoids↗
PubMed2005

The photochemistry of lipoic acid: photoionization and observation of a triplet excited state of a disulfide.

Under short-wavelength UV irradiation, lipoic acid (LipSS) and its reduced form, dihydrolipoic acid (DHLA), undergo photoionization processes through a bi- or monophotonic pathway. After ionization, the LipSS radical cation (LipSS*+) and radical anion (LipSS*-) are generated. LipSS*- can be converted to equimolar amounts of LipSS and DHLA through second-order decay. Triplet acetone can be quenched by LipSS and DHLA with a rate close to the diffusion-controlled limit. The mechanism was further confirmed by continuous irradiation experiments. When LipSS is directly irradiated with UVA light, the first excited triplet state of LipSS is observed, with a lifetime tau=75 ns. Characteristic reactions include triplet energy transfer to oxygen and beta-carotene and addition to isoprene. The lifetime of triplet LipSS is also shortened by addition of water and methanol.

Acetone↗
PubMed1983

Neurofilament architecture combines structural principles of intermediate filaments with carboxy-terminal extensions increasing in size between triplet proteins.

Mammalian neurofilament triplet proteins (68 K, 160 K and 200 K) have been correlated by a biochemical, immunological and protein chemical study. The 160 K and 200 K triplet proteins are intermediate filament proteins in their own right, since they reveal the alpha-helical coiled-coil rod domain analyzed in detail for the 68 K protein. Triplet proteins display two distinct arrays. Their amino-terminal region built analogously to non-neuronal intermediate filament proteins should allow a co-polymerization process via the interaction of coiled-coil domains. The extra mass of all triplet proteins is allocated to carboxy-terminally located extensions of increasing size and unique amino acid sequences. These may provide highly charged scaffolds suitable for interactions with other neuronal components. Such a domain of 68 K reveals, in sequence analysis, 47 glutamic acids within 106 residues. The epitope recognized by a monoclonal antibody reacting probably with all intermediate filament proteins has been mapped. It is located within the last 20 residues of the rods, where six distinct intermediate filament proteins point to a consensus sequence.

Amino Acid Sequence↗