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Biomedical subjects

P Yu

Publications and source records attributed to P Yu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Delayed stochastic differential model for quiet standing.

A physiological quiet standing model, described by a delayed differential equation, subject to a white noise perturbation, is proposed to study the postural control system of human beings. It has been found that the white noise destabilizes the equilibrium state, and inertia accelerates the destabilizing process, and that the position of a person is detected and processed by the person's nervous system with a delay. This paper focuses on the analysis of Hopf bifurcation and its stability in this context. Based on the analytical predictions confirmed by numerical simulations, it has been shown that the posture of a person is controlled in such a way that possible amplitude oscillations are minimized.

Computer Simulation↗
PubMed2001

Gait analysis in rats with peripheral nerve injury.

Rats are commonly used to study peripheral nerve repair and grafting. The traditional footprint method to assess functional recovery is messy, indirect, and not useful when contractures develop in the animal model. The aim of the present study was to establish an accurate, reproducible, but simple, method to assess dynamic limb function. The basic quantitative aspects of a normal gait were characterized from 59 recorded walks in 23 rats. The video was digitized and analyzed frame by frame on a personal computer. Seven parameters of the gait were assessed: (1) walking speed; (2) stance phase, swing phase and right to left stance/swing ratio; (3) step length and step length ratio; (4) ankle angles at terminal stance and midswing; (5) tail height; (6) midline deviation; and (7) tail deviation. These gait parameters were then applied to groups of animals with sciatic (group S), tibial (group T), and peroneal (group P) nerve injuries. A discriminant analysis was performed to analyze each parameter and to compute a functional score. We found that the video gait analysis was superior to the footprint method and believe it will be very useful in future studies on peripheral nerve injury.

Animals↗
PubMed2001

Numerical modelling of the perturbation of HIV-1 during combination anti-retroviral therapy.

A competitive, chaos-free, implicit, finite-difference method is developed and used for a novel deterministic model for the perturbation of HIV by combination antiretroviral therapy. The compartmental model monitors the interaction between HIV and CD4(+) T cells, its principal target and site of replication in vivo, in the presence of reverse transcription inhibitors and protease inhibitors. The model exhibits two steady states, an uninfected (trivial) steady state (with no virus present) and an endemically infected state (with virus and infected T cells present). Stability and bifurcation analyses together with numerical simulations of the resulting dynamical system are reported.

Anti-HIV Agents↗
PubMed2001

Objective voice analysis for dysphonic patients: a multiparametric protocol including acoustic and aerodynamic measurements.

The purpose was to determine the clinical value of a multiparametric objective voice evaluation protocol including acoustic and aerodynamic parameters measured mainly on a sustained /a/. This was done by comparison with perceptual analysis of continuous speech by a jury composed of 6 experienced listeners. Voice samples (continuous speech) from 63 male patients with dysphonia and 21 control subjects with normal voices were recorded and assesed by a jury of listeners. The jury was instructed to classify voice samples according to the G (overall dysphonia) component of the GRBAS score on a 4-point scale ranging from 0 for normal to 3 for severe dysphonia. Objective parameters were recorded on an EVA workstation. As usual with this type of system, parameters were measured mainly on a sustained /a/. Measured parameters included fundamental frequency (F0), intensity, jitter, shimmer, signal-to-noise ratio, Lyapunov coefficient (LC), oral airflow (OAF), maximum phonatory time (MPT), and vocal range (range). Estimated subglottic pressure (ESGP) was determined on a series of /pa/. Discriminant analysis was performed to detect correlation between jury classification and combinations of parameters. Results showed that a nonlinear combination of only six parameters (range, LC, ESGP, MPT, signal-to-noise ratio, and F0) allowed 86% concordance with jury classification. Discussion deals with the relative importance of the different objective parameters for discriminant analysis. Special emphasis is placed on two measurements rarely made in routine clinical workup, i.e., estimated subglottic pressure and Lyapunov coefficient.

Adult↗
PubMed2001

Synthesis and characterization of a tetranucleotide analogue containing alternating phosphonate-amide backbone linkages.

Described herein is the synthesis and characterization of a tetranucleotide, 5'-dC-phosphonate-T-amide-T-ophosphonate-dC (III), in which the C-T and T-C steps contain a phosphonate backbone bond and T-T is a peptide nucleic acid dimer unit (neutral backbone). The 5'- and 3'-OH groups of the tetramer can be further derivatized and, thus, the compound is a potential building block for longer oligonucleotides which will contain alternating backbone modifications at designated positions. The synthesis involved first the preparation of two hybrid peptide-deoxyribose dinucleotides, CT-CO (I) and N-CT (II) (C and T are nucleobases; CO and N are carboxylic and amino terminal, respectively); each is linked through a phosphonate linkage. A condensation reaction between the two dimers, followed by deprotection, resulted in the formation of a peptide linkage to give the desired tetramer III. The reaction conditions used are mild to afford products in moderate to excellent yields. The DNA-PNA-DNA tetramer, d(CTTC), is a substrate for T4 kinase but fails to give a ligation product, even though NMR shows weak interactions between the tetramer III with its complementary sequence, d(GAAG).

Amides↗
PubMed2001

Gallbladder muscle dysfunction in patients with chronic acalculous disease.

BACKGROUND & AIMS: The mechanisms responsible for the abnormalities of gallbladder emptying in patients with chronic acalculous gallbladder disease (AGD) have not been elucidated. This study was designed to determine whether a muscle defect could explain this gallbladder dysfunction. METHODS: Gallbladder contraction induced by a continuous intravenous cholecystokinin octapeptide (CCK-8) infusion was determined by ultrasonography in control subjects, patients with AGD, pigment stones, and cholesterol stones. Muscle cells were obtained by enzymatic digestion. (125)I-CCK-8 binding and [(35)S]guanosine triphosphate gamma S (GTP gamma S) binding studies were performed. RESULTS: In vivo gallbladder contraction induced by CCK-8 was significantly lower in AGD (29.4%) and cholesterol stones (28.8%) than in pigment stones (59.8%) and normal controls (57.8%; P < 0.01). In vitro muscle cell contraction induced by CCK-8 was also lower in AGD than in pigment stones. It remained impaired in AGD after stimulation with the G-protein activators GTP gamma S and AlF(4) and with the second messenger 1,2-dioctanoyl-sn-glycerol. However, GTP gamma S binding induced by CCK-8 and vasoactive intestinal polypeptide and the binding capacity of CCK receptors were not different between AGD and pigment stones. CONCLUSIONS: These findings suggest that there is a good correlation between in vivo and in vitro gallbladder response to CCK-8 in patients with AGD. Unlike those found in cholesterol stones, the muscle defects in AGD appear to reside in the contractile apparatus.

Cell Membrane↗
PubMed2001

A de novo complex chromosomal rearrangement with a translocation 7;9 and 8q insertion in a male carrier with no infertility.

A de novo complex chromosomal rearrangement (CCR) involving chromosomes 7, 8 and 9 in a male carrier was ascertained through his healthy wife's recurrent spontaneous abortions. Six pregnancies over eight years resulted in four spontaneous abortions and two livebirths who died perinatally due to abnormal vital signs. Cytogenetic analyses utilizing high resolution chromosome banding technique showed a deletion of band in a der(7) chromosome and an extra band inserting at 8q21.2. Another extra band was also observed at the band 9p24, but it could not be karyotypically determined. Fluorescent in-situ hybridization using chromosome 7 and 8 specific microdissected library as probes confirmed the insertion of a segment from the translocated chromosome 7 into a chromosome 8, and additionally revealed a translocation between chromosomes 7 and 9. The karyotype of the CCR carrier was determined as 46,XY,t(7;9)(q22;p24),ins(8;7)(q21.2;q22q32).ish der(9)(wcp7+);ins(8;7)(wcp8+,wcp7+). Comparing with previously reported male CCR carriers with our case, we conclude that male CCR carriers may not always present with infertility or subfertility phenotypes. This may suggest that rare transmission of male carriers could result from abnormal chromosomal rearrangements during meiosis and gametogenesis in addition to frequent infertility.

Abortion, Habitual↗
PubMed2001

Quantitative assessment of cranial defect healing and correlation with the expression of TGF-beta.

Circular parietal defects from 3 to 12 mm in diameter were made in 45 6-month old skeletally mature guinea pigs, and animals were sacrificed after survival periods of 3 days to 12 weeks. The original defect was harvested in continuity with a rim of surrounding bone and the adjacent dura and pericranium. After 12 weeks, all 3 and 5 mm defects were completely covered by a bridge of bone, while residual defects were noted within the 8 and 12 mm wounds. Percentage of new bone formation was significantly higher within 3 mm defects, than in all larger defects at each time interval from 1 week on (P < .05), reaching a mean of 93% in 3 mm defects and remaining below a mean of 31% in the remaining defect sizes. Immunolocalization demonstrated an osteogenic front in which the osteoblasts stained strongly for all isoforms of TGF-beta, with the intensity decreasing after the majority of the defects had reossified; this front was located at the advancing bone edge of the defect as well as the endocranial side adjacent to the dura. In conclusion, isoforms of TGF-beta are upregulated during a limited "window" of time corresponding to the period of calvarial reossification, and are localized to osteoblasts within an osteogenic front at the periphery and dural surfaces of the defects.

Animals↗
PubMed2001

The effect of trauma program registry on reported mortality rates.

BACKGROUND: This study assesses the relationship that the brand of trauma program registry (TPR) has on mortality rate (MR) in the reports prepared by the American College of Surgeons Committee on Trauma (ACSCOT) trauma center (TC) site surveyors. METHODS: Data from 242 ACSCOT adult TC survey reports (88 Level I, 115 Level II, and 39 Level III) were analyzed for annual trauma volume, injury severity score (ISS), MR, and TPR. Six TPR (A through F) were identified; group F was a composite of several infrequently used TPRs. This report focuses on the ISS range 16-24 because of the likelihood that the mean for each TC would be near 20 and MR is high enough so that a difference, if present, could be statistically documented. RESULTS: For the total group, MR showed no correlation with TC volume or TC level for ISS 16-24. MR was significantly different according to which TPR was used by the TCs. The MR is less (4.8%) for 14 high volume TCs (over 1200 admits) using TPR A compared with 33 low volume TCs (below 800 admits) using TPR A (6.34%). CONCLUSION: The MR for ISS 16-24 in ACSCOT-surveyed TCs differs within subgroups based on type of TPR utilized. This may reflect improper use of the software programs. Enhanced skill in the application of software programs designed to generate ISS scores is essential if meaningful studies on the effects of improved trauma care on MR are to be conducted. Hand scored ISS by trained personnel may circumvent this problem.

Confounding Factors, Epidemiologic↗
PubMed2001

Partial frontolateral laryngectomy with epiglottic reconstruction for management of early-stage glottic carcinoma.

OBJECTIVES: The aim of this study was to demonstrate that partial frontolateral laryngectomy with epiglottic reconstruction (PFLER) is an effective therapeutic option for treatment of T1 and T2 glottic carcinoma. STUDY DESIGN: Retrospective study. METHODS: Between 1982 and 1997, we treated 127 cases of early glottic carcinoma with PFLER. Early glottic carcinoma was staged using the Union Internationale Contre le Cancer TNM classification as either T1N0M0 (62 cases) or T2N0M0 (65 cases). Selection criteria, depending on the limits of exeresis, must remain glottic carcinoma with less than 0.5 cm of anterior subglottic involvement, with no involvement of the supraglottic space or laryngeal side of the epiglottis, with involvement of only one arytenoid, and with good mobility of both arytenoids even if vocal cord mobility is decreased. RESULTS: Postoperative recovery was uneventful in all cases, and all patients but one were able to breath and eat normally. The failure involved a patient with a permanent gastrostomy. As with other partial laryngectomy techniques, the main drawback of PFLER was deterioration of voice quality. All patients presented hoarseness and weakness of the voice. Five-year survival rates calculated according to the Kaplan-Meier method were 91% (standard error, 5%) in the T1N0M0 group and 86% (standard error, 5%) in the T2N0M0 group. No recurrence was observed in the T1N0M0 group. Local control was successful in 92% in the T2N0M0 group after a median follow-up of 5 years. CONCLUSION: These findings show that PFLER is an effective therapeutic option in selected cases of early T1N0M0 or T2N0M0 glottic carcinoma.

Carcinoma, Squamous Cell↗
PubMed2001

The regulation of T cell homeostasis and autoimmunity by T cell-derived LIGHT.

Costimulatory molecules on antigen-presenting cells (APCs) play an important role in T cell activation and expansion. However, little is known about the surface molecules involved in direct T-T cell interaction required for their activation and expansion. LIGHT, a newly discovered TNF superfamily member (TNFSF14), is expressed on activated T cells and immature dendritic cells. Here we demonstrate that blockade of LIGHT activity can reduce anti-CD3-mediated proliferation of purified T cells, suggesting that T cell-T cell interaction is essential for this proliferation. To test the in vivo activity of T cell-derived LIGHT in immune homeostasis and function, transgenic (Tg) mice expressing LIGHT in the T cell lineage were generated. LIGHT Tg mice have a significantly enlarged T cell compartment and a hyperactivated peripheral T cell population. LIGHT Tg mice spontaneously develop severe autoimmune disease manifested by splenomegaly, lymphadenopathy, glomerulonephritis, elevated autoantibodies, and severe infiltration of various peripheral tissues. Furthermore, the blockade of LIGHT activity ameliorates the severity of T cell-mediated diseases. Collectively, these findings establish a crucial role for this T cell-derived costimulatory ligand in T cell activation and expansion; moreover, the dysregulation of T cell-derived LIGHT leads to altered T cell homeostasis and autoimmune disease.

Animals↗
PubMed2001

A novel isoform of beta-spectrin II localizes to cerebellar Purkinje-cell bodies and interacts with neurofibromatosis type 2 gene product schwannomin.

We report the identification of a full-length novel beta-spectrin II gene (betaSpIIsigma2) in human brain. The betaSpIIsigma2 gene has 32 exons encoding an actin-binding domain, followed by 17-spectrin repeats, and a short COOH-terminal regulatory region that lacks the Pleckstrin homology (PH) domain. Pair-wise sequence analysis showed an additional 36 and 28 amino acids located at the NH2 and COOH-terminal regions of betaSpIIsigma2, respectively. Northern-blot analysis showed an abundant expression of betaSpIIsigma2 transcripts in brain, lung, and kidney. Western-blot analysis confirmed the predicted approximately 225 kD molecular size of betaSpIIsigma2 protein in these same tissues. In brain, immunofluorescent staining revealed that betaSpIIsigma2 was enriched in cerebellar neurons, with specific enrichment in Purkinje cell bodies, but not in dendrites. Of considerable interest, neurofibromatosis type 2 (NF2) gene product schwannomin was found to co-immunoprecipitate with betaSpIIsigma2 in cultured Purkinje cells. These results suggest that betaSpIIsigma2 may play an important role in the assembly of the specialized plasma membrane domain of Purkinje neurons and that schwannomin may be involved in actin-cytoskeleton organization by interacting with betaSpIIsigma2.

Amino Acid Sequence↗
PubMed2001

Effect of a composite membrane of chitosan and poloxamer gel on postoperative adhesive interactions.

Excessive postoperative adhesion formation is a major result of surgery. The adhesion reduction effects of a chitosan membrane and poloxamer gel barrier were measured in a rat peritoneal model. Forty-four male Sprague-Dawley rats were divided into four groups (control, poloxamer, chitosan, and poloxamer+chitosan sandwich). Two cm2 of cecal serosa and the adjacent abdominal wall were abraded. The denuded cecum was covered with either a chitosan membrane, a poloxamer gel, chitosan in a sandwich configuration with poloxamer on both sides, or neither (control group) and apposed to the abdominal wall. Fourteen days after surgery adhesions were graded using a whole-number scoring system of zero to five. Adhesion strength was determined using a whole-number system of one to four. Adhesion area was measured on a continuous scale of adhesion severity. Adhesion grades were highest in the control group (5.00 +/- 0.00) and were significantly (P < 0.05) lower in the poloxamer group (3.50 +/- 1.35), the chitosan group (1.64 +/- 1.63), and the poloxamer+chitosan group (1.18 +/- 1.25). The two chitosan-containing groups also had significantly (P < 0.05) reduced adhesion grades in comparison with the poloxamer group. Adhesion area in both chitosan-containing groups was reduced in comparison with control and adhesion strength was reduced significantly (P < 0.05) in all groups compared with control. The poloxamer+chitosan group had significantly (P < 0.05) reduced adhesion strength versus poloxamer only. There was a significant (P < 0.05) linear correlation (r = 0.931, P < 0.001) between adhesion grade and adhesion strength. We conclude that chitosan and the combination of poloxamer+chitosan were shown to effectively reduce adhesion area, grade, and strength.

Adhesiveness↗
PubMed2001

[Identification of mutation of the X-linked juvenile retinoschisis gene].

OBJECTIVE: To elucidate the pathogeny of X-linked retinoschisis(XLRS) and evaluate its value in direct gene diagnosis. METHODS: Polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP) assay was performed to examine exons of XLRS1 gene in six unrelated retinoschisis cases (3 families and 3 sporadic cases), and fragments with a mobility shift were sequenced to identify the mutation. The deletion mutations were further identified by Southern blotting analysis. RESULTS: Three deletions that eliminate exon 1, exon 2, and exon 3 were found in 4 patients of one family. There was severe effect of the mutation in the coding region. Three kinds of mutations were found in exon 4: Glu72Lys, Glu72Gln, Gly70Ser. CONCLUSION: XLRS is caused by mutation of the XLRS1 gene. The finding helps establish a fast and effective direct diagnosis.

Adolescent↗
PubMed2001

[The quantitative analysis of voice disease based on fractal method].

The fractal method is employed to check the voice diseases. The severity of pathological changes of human voice can be analyzed objectively and quantitatively with different fractal dimensions. With this method we can end up the history of judging the voice with subjective hearing and it is of great importance to the development of laryngology.

Fractals↗
PubMed2001

[The language healing system of deaf children based on wavelet transform].

In the language healing system of deaf children, the wavelet transform method is employed to describe the time-varying characteristics of speech signals, improve the resolution of speech spectrum and make the speech characteristics more obvious. The speech spectrum information shown in this system is easier for deaf children to observe and understand and it is of great importance to the language healing of deaf children.

Child↗
PubMed2001

Effects of microinjection of melatonin and its receptor antagonists into anterior hypothalamic area on blood pressure and heart rate in rats.

AIM: To examine the effects of microinjection of melatonin and its receptor antagonists into the anterior hypothalamic area (AHA) on blood pressure (BP) and heart rate (HR) in normotensive and stress-induced hypertensive rats. METHODS: Melatonin and its receptor antagonists were microinjected into the AHA, then BP, mean arterial pressure (MAP), and HR were synchronously recorded. RESULTS: Microinjection of melatonin produced a fall in MAP. Prazosin, an antagonist of melatonin ML2 receptor, could not antagonize the depressive response induced by melatonin. While luzindole, a competitive antagonist of melatonin ML1 receptor, was able to almost completely prevented the depressive response induced by injection of melatonin. CONCLUSION: Melatonin acts as a hypotensive factor and the effects are mainly due to activation of ML1 receptors in rat brain, and the AHA may be one of the important central areas where melatonin can exert modulatory effects on BP and HR.

Animals↗