3D simulations of hydrodynamic drag forces on two porous spheres moving along their centerline

This paper numerically evaluates the hydrodynamic drag force exerted on two highly porous spheres moving steadily along their centerline through a quiescent Newtonian fluid over a Reynolds number ranging from 0.1 to 40. At creeping-flow limit, the drag forces exerted on both spheres were approximately identical. At higher Reynolds numbers the drag force on the leading sphere (sphere #1) was higher than the following sphere (sphere #2), revealing the shading effects produced by sphere #1 on sphere #2. At dimensionless diameter beta<2 (beta=d(f)/2k(0.5), d(f) and k are sphere diameter and interior permeability, respectively), the spheres can be regarded as "no-spheres" limit. At increasing beta for both spheres, the drag force on sphere #2 was increased because of the more difficult advective flow through its interior, and at the same time the drag was reduced owing to the stronger wake flow produced by the denser sphere #1. The competition between these two effects leads to complicated dependence of drag force on sphere #2 on beta value. These effects were minimal when beta became low.

Ultra-short metformin pretreatment for clomiphene citrate-resistant polycystic ovary syndrome

OBJECTIVE

To evaluate the effect of ultra-short (12 days) metformin pretreatment in clomiphene-citrate (CC) resistant polycystic ovary syndrome (PCOS).

METHOD

Eighty women with CC-resistant PCOS were randomly allocated to metformin pretreatment or usual treatment. Forty women received 1500 mg metformin daily for 12 days, followed by clomiphene 150 mg daily for 5 days along with metformin. Forty women (control group) received the same dose of clomiphene but no metformin pretreatment.

RESULTS

In the metformin group, 17 (42.5%) women ovulated, and 6 (15%) conceived. In the control group, 5 (12.5%) women ovulated but none conceived. Compared with the control group, the metformin group had significantly higher ovulation (P = 0.03) and pregnancy rates (P = 0.026).

CONCLUSION

Twelve days of metformin pretreatment improves ovulation and pregnancy rates in women with CC-resistant PCOS.

Influence of UNOS status on chance of heart transplantation and posttransplant survival

This study was designed to compare the chance of heart transplantation (HTx) and survival among patients in different UNOS statuses in Taiwan.

METHODS AND RESULTS

From 1996 to 2002, among 203 patients on the heart transplant waiting list, 127 patients had undergone HTx up to December 2002 with 71 dead while waiting, and 5 still alive without transplantation. This study included those 198 patients who had either undergone HTx or who died. At the time of registry, 40 patients were at status IA, 57 at IB, and 101 at II. Nineteen (47.5%) of 40 status IA patients underwent HTx with a mean waiting time of 92 +/- 116 days and median waiting time of 35 days. The 1-month survival was 84%, and 1-year survival was 58%. Seven (64.9%) of 57 status IB patients underwent HTx with a mean waiting time of 85 +/- 100 days and a median waiting time of 40 days. Both 1-month and 1-year survivals were 92%. Seventy-one (70.3%) patients among 101 status II patients underwent HTx. Their mean waiting time was 134 +/- 135 days and median waiting time was 86 days. Their 1-month survival was 95%, and 1-year survival was 85%.

CONCLUSION

Although UNOS status IA patients had a shorter waiting time, their chance to undergo HTx was lower than those in either status IB or status II. The UNOS status IA heart-waiting patients showed lower posttransplant 1-month and 1-year survival rates.

Do patients with acute liver failure have a better chance to receive liver grafting?

OBJECTIVE

Patients with acute hepatic failure (AHF) were always given first priority on the transplant waiting list. We investigated whether AHF patients will deprive other patients on the waiting list of the chance of liver transplantation (LTx).

METHODS AND RESULTS

From January 1999 to March 2003, a total of 423 patients were on the transplant waiting list at the National Taiwan University Hospital. Sixty-five of the patients had AHF caused by hepatitis-B-related disease (HBV, n = 52, 80%), Wilson disease (n = 3, 4.6%), drug-induced AHF (n = 3, 4.6%), and other causes (n = 7, 10.8%).Thirty-three patients died and 16 survived by medical treatment. Two received LTx abroad and 14 underwent LTx at our hospital (7 living-related; 7 cadaver). A total of 140 patients died while waiting for a transplant during the period studied. Of them, 107 were among 358 non-AHF patients (30%), and time-to-death interval was 133 +/- 175 days (median: 62); 33 were among 65 AHF patients (51%); time to death was 19 +/- 28 days (median: 8). There were 35 cadaver donor livers available during the period; 28 of 358 non-AHF patients (7.8%), and 7 of 65 AHF patients (10.7%) received cadaveric LTx. Their waiting time totaled 342 +/- 316 and 12 +/- 9 days, respectively (P < .0001).

CONCLUSION

Most AHF patients died unless they received liver grafts. Even with a higher priority assigned to them, AHF patients still have little chance to get a cadaver donor liver in Taiwan, and non-AHF patients have an even slimmer chance. Therefore, we need to encourage liver donation from living-related donors.

Surfaces with occlusions from layered stereo

We propose a new binocular stereo algorithm that estimates scene structure as a collection of smooth surface patches. The disparities within each patch are modeled by a continuous-valued spline, while the extent of each patch is represented via a pixelwise partitioning of the images. Disparities and extents are alternately estimated in an iterative, energy minimization framework. Experimental results demonstrate that, for scenes consisting of smooth surfaces, the proposed algorithm significantly improves upon the state of the art.

Real-time PCR for rapid genotyping of angiotensin-converting enzyme insertion/deletion polymorphism

OBJECTIVE

To develop a real-time PCR technique for detection of the insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene.

DESIGN AND METHODS

Three primers were designed for performing real-time PCR in the presence of SYBR Green I as flurochrome followed by melting curve analysis. Forty human genomic DNA that have been genotyped by two-rounds of conventional PCR were used for evaluation of this technique.

RESULTS

Melting curve analysis indicated the melting peak at 73.9 degrees C and 76.2 degrees C corresponding to the presence of I and D alleles, respectively. Comparable genotyping results were obtained by both conventional and real-time PCR. Besides, the mistyping of ID allele individuals by the first run of conventional PCR were accurately genotyped by single-tube real time PCR.

CONCLUSIONS

The real-time PCR method presented in this study provides a rapid and sensitive way for genotyping of ACE gene that may be suitable for large-scale clinical and epidemiologic study.

Cardiotoxicity in imipramine intoxication: report of one case

Imipramine is the most commonly prescribed tricyclic antidepressant of acute life threatening self-poisoning. We report a 15-month-old boy of accidental poisoning with imipramine, who developed generalized tonic-clonic convulsions and drug-related cardiac conduction abnormalities with PR prolongation, QRS widening, and QTc lengthening. The patient's imipramine level was 1389 ng/ml. The rapid resolution of intraventricular conduction delay and normalization of the QRS-T complexes after gastric lavage, installation of activated charcoal and alkalinization of the blood strongly implicates imipramine intoxication in the etiology of the cardiotoxicity. The patient made a full recovery without neurological sequelae.

Real-time quantitative PCR analysis for alpha-thalassemia-1 of Southeast Asian type deletion in Taiwan

Since homozygosity of the alpha-thalassemia-1 of Southeast Asian (SEA) type deletion results in hydrops fetalis, a novel protocol based on the real-time quantitating polymerase chain reaction (PCR) technique has been developed to quantify the intact and aberrant alpha-globin genes in adults. The ratio of the normal/SEA-bearing alpha-globin genes was expressed in cycle threshold (C(T)) values. Theoretically, a relative ratio of one to one was anticipated in individuals carrying the SEA type deletion. Twenty-five heterozygous and 20 normal cases were analyzed retrospectively with this protocol. Data showed that the CT values for the intact alpha-globin gene allele and the allele bearing the SEA type deletion in carriers were 28.74+/-1.49 and 26.46+/-2.05, respectively. Therefore, the ratio of normal/SEA type deletion-bearing alpha-globin genes in the carriers was 1.09+/-0.043. No ambiguous results were observed from other less common genotypes associated with alpha-thalassemia, such as the Philippine type deletion. Based on the results, we concluded that this protocol could provide a rapid method to mass screen carriers with alpha-thalassemia-1 of SEA type deletion in this region.

The dilemma of "to-be or not-to-be": needs and expectations of the Taiwanese cadaveric organ donor families during the pre-donation transition

There has been little study of the Chinese cadaveric donor family's decisions to donate organs within the Chinese cultural framework. A convenience sample of 25 cadaveric donor family members (12 men, 13 women) who gave their consent to donation at National Taiwan University Hospital agreed to participate in this study and completed in-depth interviews. Data were analyzed by a three-steps within-method qualitative triangulation method. The factors influencing the donor family's decisions to donate organs, the needs of donor families, and their expectations of health care providers during the pre-donation transition--the critical period of time between signing a donation and consent to organ harvesting--were examined. The background context and a conceptual framework were further developed to discuss and depict this phenomenon. This project aims to broaden the horizon on organ donation and contribute to the understanding of some of the psychodynamic issues in the Chinese family in Taiwan.

Specificity of the histopathological triad for the diagnosis of toxoplasmic lymphadenitis: polymerase chain reaction study

Toxoplasmosis is a common cause of lymphadenopathy, but toxoplasmic cysts are not usually found in histological sections used for establishing diagnosis, except on extremely rare occasions. The histopathological triad of florid reactive follicular hyperplasia, clusters of epithelioid histiocytes, and focal sinusoidal distention by monocytoid B cells has been considered to be diagnostic of toxoplasmic lymphadenitis, but the validity of the histopathological triad is based indirectly on serological correlation only. The demonstration of Toxoplasma gondii DNA in lymph nodes displaying the histopathological triad will indicate the validity of the histopathological triad as the criterion for the histopathological diagnosis of toxoplasmic lymphadenitis. We used frozen tissues of 12 lymph nodes with the histopathological triad and tissues of 27 lymph nodes from patients with various other conditions (including 13 cases of follicular lymphoid hyperplasia, FLH; three cases of dermatopathic lymphadenopathy, DPL; two cases of plasmacytosis; two cases of Castleman's disease; two cases of metastatic adenocarcinoma; and five cases of lymphoma) to detect T. gondii DNA by polymerase chain reaction. Ten out of 12 lymph nodes with the triad and six out of 27 lymph nodes without the triad were positive for T. gondii DNA. Thus, the sensitivity of the triad was 62.5% (10/16) and the specificity was 91.3% (21/23). The predictive value of positive tests was 83.3% (10/12) and the predictive value of negative tests was 77.7% (21/27). The six cases positive for T. gondii DNA without the triad were four cases of FLH, one case of DPL, and one case of plasmacytosis. None of the neoplastic diseases was positive. The false positive and negative cases could be due to sampling problems or past T. gondii infection. The results confirm that the histopathological triad is highly specific for the diagnosis of toxoplasmic lymphadenitis and can be used confidently.

Spontaneous closure of ventricular septal defects in the first year of life

BACKGROUND AND PURPOSE

The recent increase in the prevalence of ventricular septal defect (VSD) has been ascribed to the improved detection of small defects with echocardiography and the wider use of screening. The aim of this study was to determine the prevalence and timing of spontaneous closure of specific types of VSD in neonates using echocardiographic screening and follow-up.

METHODS

Two-dimensional color Doppler echocardiography was performed in 3,472 clinically normal full-term neonates born at Cathay General Hospital to detect isolated VSD. The relative prevalence of muscular versus perimembranous defects and their outcome in the first year of life were evaluated.

RESULTS

VSD was found in 74 neonates (34 male, 40 female), resulting in a prevalence of 21.3/1,000 live births. There were 48 muscular, 25 perimembranous, and one subpulmonic defects. Of the 74 patients, 11 were lost to follow-up. Within the observation period of 12 months, spontaneous closure occurred in 40 patients in the muscular group and in six patients in the perimembranous group. The overall rate of spontaneous closure was 73% by the end of the first year. Only five patients with perimembranous defects received digoxin therapy.

CONCLUSIONS

The prevalence of VSD in this series of neonates was 21.3/1,000 live births. The most common location of VSD in the neonatal period was in the region of the muscular septum. Muscular defects were more likely to close spontaneously than perimembranous defects. Most muscular defects underwent spontaneous closure during the 12-month follow-up period.

Induction of disabled-2 gene during megakaryocyte differentiation of k562 cells

Megakaryocyte differentiation is often accompanied by the changes of gene expression pattern. Here we reported that the expression of DAB2, a putative adaptor protein in cell signaling, was induced at the protein and mRNA levels upon 12-O-tetradecanoylphorbol-13-acetate-mediated megakaryocyte differentiation of human chronic myeloid leukemic K562 cells. On the other hand, the differentiation agents DMSO and retinoic acid had no effect on DAB2 expression. Analysis of promoter activity with the human DAB2 luciferase reporter constructs suggested that the regulation is partially at the transcriptional level. The responsive sequences located within an 80-bp DAB2 promoter region. To determine the involvement of MEK1-p42/p44 MAPK pathway in mediating DAB2 gene expression, we have performed the following experiments and found that (i) there was sustained activation of p42/p44 MAPK, but not p38 MAPK, upon K562 cells differentiation; (ii) application of MEK1 inhibitor U0126 reduced the expression of DAB2 protein, mRNA and promoter activity, as well as cell differentiation; (iii) constitutively active MEK1 increased DAB2 promoter activity; and (iv) dominant negative ERK2 abolished constitutively active MEK1-induced DAB2 promoter activity. Taken together, our results indicate that DAB2 gene is induced upon megakaryocyte differentiation by the MEK1-p42/p44 MAPK pathway and may define a new role of DAB2 in hematopoietic cell differentiation.

[The development of a competency-based clinical performance examination model in maternity nursing for BSN graduates]

The purpose of the study was to establish a competency-based clinical performance examination model in maternity nursing for baccalaureate students. Action research was the main research methodology used in the study. A committee, consisting of nursing faculty, students and experienced obstetric nurses, was established to develop the model. Based on intensive literature reviews and standards of nursing practice in Taiwan, the first draft of the model, including the content and process, was created by the committee. The draft then was revised twice after expert review and pilot testing. The revised version of the model was formally implemented into the curriculum to examine the competencies of forty-one BSN students at the end of the perinatal nursing course. Responses from students, clinical examiners, clinical staff and clients were all gathered and integrated to refine the model. The model has content, expert and discriminative validity. The reliability of the model was proven by the high consistency in administration and scoring of the model among clinical examiners.

A common precursor for the three subunits of L-glutamate oxidase encoded by gox gene from Streptomyces platensis NTU3304

A segment of DNA containing the L-glutamate oxidase (gox) gene from Streptomyces platensis NTU3304 was cloned. The entire nucleotide sequence of the protein-coding portion consisting of 2130 bp (710 codons, including AUG and UGA) of the cloned DNA fragment was determined. The gox gene contained only one open reading frame (ORF) which coded for a 78-kDa polypeptide, the precursor of active extracellular Gox. Mature Gox is composed of three subunits, designated as alpha, beta, and gamma, with molecular masses of 39, 19, and 16 kDa, respectively. Analyses of the N-terminal amino acid sequences of the subunits revealed that the order of subunits in the precursor polypeptide encoded by the ORF, from N-terminus to C-terminus, is alpha-gamma-beta. The presence of the flavin adenine dinucleotide (FAD)-binding motif place Gox as a member of the flavoenzyme family. Furthermore, a negative effect of glucose on the biosynthesis of Gox was observed when it was used as carbon source.

Impact of cadaveric organ donation on Taiwanese donor families during the first 6 months after donation

OBJECTIVE

Organ donation is a complex decision for family members of Asian donors. The impact of cadaveric organ donation on both Chinese and Western donor families has not been well investigated within a cultural framework. The purposes of this study were to follow Chinese family members' appraisal of their decision to donate organs, to explore the possible negative and positive impacts of organ donation on their family life, and to determine what help they expected from healthcare providers during the first 6 months after donation.

METHODS

Twenty-two family members (10 men and 12 women) of cadaveric organ donors who signed consent forms at an organ transplant medical center in Taiwan participated in this project and completed in-depth interviews during the sixth month after donation.

RESULTS

Participants were 25 to 56 years old (mean = 48.15 +/- 8.31 years). The type of kinship of the participants included the donor's parents, older sister, and spouse. Subjects reported several negative impacts: worry about the donor's afterlife (86%), stress due to controversy among family members over the decision to donate (77%), and stress due to others' devaluation of the donation (45%). Positive impacts reported by the subjects included having a sense of reward for helping others (36%), having an increased appreciation of life (32%), having closer family relationships (23%), and planning to shift life goals to the study of medicine (9%). Subjects expected the transplant team to provide information about organ recipients (73%), to submit the necessary documents so that family members could receive healthcare payments from the insurance company (68%), to help resolve legal proceedings and settlements associated with accidents (64%), and to not overly publicize their decision to donate (64%).

CONCLUSIONS

Although all of the subjects reported that organ donation was the right decision, the decision to donate did not protect Taiwanese donor families from negative psychocognitive bereavement. The impacts of organ donation were affected by the subject's social cultural, spiritual, and legal context and the nature of their bereavement.

Central venous catheter-induced atrial ectopic tachycardia with reverse alternating Wenckebach periods

A centrally inserted venous catheter may cause atrial ectopic tachycardia. The association of atrial ectopic tachycardia with spontaneous reverse alternating Wenckebach periodicity has rarely been reported. We describe a 4-year-old boy with tetralogy of Fallot who developed atrial ectopic tachycardia with reverse alternating Wenckebach periods postoperatively after central venous catheter placement. All such episodes emerged from a 3:2 atrioventricular block, followed by runs of 2:1 atrioventricular block with progressive shortening of the conducted PR intervals. Normal sinus rhythm returned after the catheter was withdrawn to the superior vena cava. Reverse alternating Wenckebach periodicity may be a tachycardia-dependent physiologic phenomenon.

Real-time PCR for quantitative detection of Toxoplasma gondii

The protozoan Toxoplasma gondii is one of the most common infectious pathogenic parasites and can cause severe medical complications in infants and immunocompromised individuals. We report here the development of a real-time PCR-based assay for the detection of T. gondii. Oligonucleotide primers and a fluorescence-labeled TaqMan probe were designed to amplify the T. gondii B1 gene. After 40 PCR cycles, the cycle threshold values (C(T)) indicative of the quantity of the target gene were determined. Typically, a C(T) of 25.09 was obtained with DNA from 500 tachyzoites of the T. gondii RH strain. The intra-assay coefficients of variation (CV) were 0.4, 0.16, 0.24, and 0.79% for the four sets of quadruplicate assays, with a mean interassay CV of 0.4%. These values indicate the reproducibility of this assay. Upon optimization of assay conditions, we were able to obtain a standard curve with a linear range (correlation coefficient = 0.9988) across at least 6 logs of DNA concentration. Hence, we were able to quantitatively detect as little as 0.05 T. gondii tachyzoite in an assay. When tested with 30 paraffin-embedded fetal tissue sections, 10 sections (33%) showed a C(T) of <40 and were scored as positive for this test. These results were consistent with those obtained through our nested-PCR control experiments. We have developed a rapid, sensitive, and quantitative real-time PCR for detection of T. gondii. The advantages of this technique for the diagnosis of toxoplasmosis in a clinical laboratory are discussed.

Embryonic dormancy phenomenon in obstructed healthy mouse fallopian tubes

PURPOSE

A mouse model of unilateral oviductal obstruction was designed to study whether healthy oviducts can support embryo development in an advanced stage toward blastocyst hatching and implantation when the embryos in the contralateral side normally move into the uterine cavity.

METHODS

The oviducts of 80 female ICR mice (aged 5-8 weeks) were ligated unilaterally 12-40 hr postcoitus. The ligated oviducts were isolated from day 4 to 19.5 postcoitus. Embryos within the ligated oviducts were then flushed out to record the developmental stage and compared with the conceptuses in the contralateral uterine horns with unligated oviducts. Embryos recovered from ligated oviducts were then cultured in vitro to observe their potential for further development.

RESULTS

In 33 mice, 53.4% (163/305) and 86.1% (241/280) of the morphologically normal blastocysts had hatched from the zona pellucida within the obstructed tube and contralateral uterine horns, respectively, on the 5th day postcoitus. The data demonstrated that the hatching process could take place within the obstructed fallopian tube, but the timing was delayed. From 5.5 to 19.5 days postcoitus, a total of 362 implanted embryos were obtained in unligated control uterine horns, but none of the 404 embryos in the artificially obstructed oviducts were implanted. The embryos within the ligated tubes were dormant in the hatched blastocyst stage as demonstrated by their ability to continue growing (98.2%) when removed from the oviduct to an in vitro environment.

CONCLUSIONS

In this study, we demonstrate that mouse embryos can hatch, although delayed, in obstructed healthy oviducts. Tubal pregnancy is not likely to happen in artificially obstructed healthy mouse fallopian tubes, since all the viable embryos were dormant at the hatched blastocyst stage.

The Drosophila PAR domain protein 1 (Pdp1) gene encodes multiple differentially expressed mRNAs and proteins through the use of multiple enhancers and promoters

Transcription factors are often expressed at several times and in multiple tissues during development and regulate diverse sets of downstream target genes by varying their combinatorial interactions with other transcription factors. The Drosophila Tropomyosin I (TmI) gene is regulated by a complex of proteins within the enhancer that synergistically interacts with MEF2 to activate TmI transcription as muscle cells fuse and differentiate. One of the components of this complex is PDP1 (PAR domain protein 1), a basic leucine zipper transcription factor that is highly homologous to three vertebrate genes that are members of the PAR domain subfamily. We have isolated and describe here the structure of the Pdp1 gene. The Pdp1 gene is complex, containing at least four transcriptional start sites and producing at least six different mRNAs and PDP1 isoforms. Five of the PDP1 isoforms differ by the substitution or insertion of amino acids at or near the N-terminal of the protein. At least three of these alternately spliced transcripts are differentially expressed in different tissues of the developing embryo in which PDP1 expression is correlated with the differentiation of different cell types. A sixth isoform is produced by splicing out part of the PAR and basic DNA binding domains, and DNA binding and transient transfection experiments suggest that it functions as a dominant negative inhibitor of transcription. Furthermore, two enhancers have been identified within the gene that express in the somatic mesodermal precursors to body wall muscles and fat body and together direct expression in other tissues that closely mimics that of the endogenous gene. These results show that Pdp1 is widely expressed, including in muscle, fat, and gut precursors, and is likely involved in the transcriptional control of different developmental pathways through the use of differentially expressed PDP1 isoforms. Furthermore, the similarities between Pdp1 and the other PAR domain genes suggest that Pdp1 is the homologue of the vertebrate genes.

The effects of brief gamete co-incubation in human in vitro fertilization

PURPOSE

To investigate whether very short exposure of mature oocytes to sperm in vitro may affect the fertilization rates, embryo cleavage rates, and embryo quality between sibling oocytes in the same patient.

METHODS

Sibling oocytes of the same patient from 23 oocyte collection cycles were randomly allocated to the study group, with a 1-hr or 3-hr sperm-oocyte incubation, or the control group with the standard overnight gamete co-incubation. The fertilization rates, cleavage rates, and subsequent embryo quality were evaluated.

RESULTS

Our results showed no statistically significant differences in fertilization rates, embryo cleavage rates, and quality of the embryos between the study group and the control group.

CONCLUSIONS

Since the present study showed that long exposure of the oocyte to sperm has no advantage over short exposure, we prefer shortening the oocyte-sperm incubation period for reducing the negative effect induced by nonphysiologically high concentrations of spermatozoa.