Biomedical subjects

B Chen

Publications and source records attributed to B Chen.

At least 91 records · Page 5Linked to original sources

PubMed2001

Tarlov cyst as a rare cause of S1 radiculopathy: A case report.

A 37-year-old female physician presented with a chief complaint of left posterior thigh pain, which began insidiously approximately 4 months before her initial examination. Initially, she had been evaluated by her physician, and magnetic resonance imaging (MRI) was ordered. The MRI scan was reported to be within normal limits, with the exception of minimal disc bulging at L4-5. She had received physical therapy with little benefit and was referred for physiatric assessment. Review of the patient's original MRI scan showed the presence of perineurial (Tarlov) cysts within the sacral canal at the level of S2, with compression of the adjacent nerve root. Subsequent electrodiagnostic testing showed axonal degeneration consistent with an S1 radiculopathy. Tarlov cysts can be a rare cause of lumbosacral radiculopathy and should be considered in the differential diagnosis of radicular leg pain.

Adult↗

PubMed2001

Retinal and intraventricular cerebral hemorrhages in the preterm infant born at or before 30 weeks' gestation.

PURPOSE: To determine the prevalence of retinal hemorrhages and their association with cerebral intraventricular hemorrhages (IVH) in low-birth-weight preterm neonates born at or before 32 weeks' gestation. METHODS: We prospectively studied a consecutive series of 22 neonates (24-30 weeks' gestation; mean gestational age, 27 weeks; mean weight, 1065 g) admitted to the neonatal intensive care unit. Anterior segment and indirect ophthalmoscopic examination, as well as cranial ultrasonographic examination, were performed on day 1 and day 10 of life. The prevalence of retinal and intraventricular hemorrhage was tested statistically for association with obstetric and neonatal clinical variables. RESULTS: The prevalence of retinal hemorrhage was 9% (2/22; 95% CI, 3%-21%) on day 1 and 2% (1/22) on day 10. The prevalence of IVH was 27% (6/22; 95% CI, 9%-46%): 14% (3/22) on day 1 and 23% (5/22) on day 10. Retinal hemorrhages occurred with greater frequency in neonates born to women who had intrauterine infection (chorioamnionitis, P =.043) and low umbilical cord pH levels (P =.027). No association was found between the presence of retinal hemorrhage and IVH (P = 1.000), mode of delivery (ie, vaginal vs cesarean section, P = 1.000), birth weight (P =.476), or gestational age (P = 1.000). The presence of subconjunctival hemorrhage was associated with IVH (P =.046). CONCLUSIONS: Retinal hemorrhages occur in less than 10% of low-birth-weight neonates, ie, a prevalence one half that observed in term neonates (22%). The hemorrhages tend to resolve without sequelae in the first 10 days of life and occur more commonly in infants born to women with uterine infection. Retinal hemorrhages in very premature neonates are not predictive of IVH-related brain damage.

Cerebral Hemorrhage↗

PubMed2001

Combined calcitriol-pamidronate therapy for bone hyperresorption in spinal cord injury.

OBJECTIVE: To determine the biochemical effects of combined calcitriol-pamidronate therapy on bone hyperresorption in patients with spinal cord injury (SCI). METHODS: This was a retrospective study of 21 SCI inpatients (4 women and 17 men, mean age 34 years) treated for bone hyperresorption. Initial treatment was 0.5 microg oral calcitriol once daily and 1,250 mg CaCO3 twice a day (1000 mg elemental calcium/day). On days 4 through 6 following the initial treatment, patients received 30 mg pamidronate intravenously once daily (total of 3 doses). Urinary N-telopeptide (NTx) and calcium excretion rates, and serum parathyroid hormone (PTH), 25-hydroxyvitamin D (25-D), 1,25-dihydroxyvitamin D (1,25-D), calcium, and phosphorus levels were measured within 2 weeks prior to and 2 weeks following pamidronate therapy. RESULTS: Patients demonstrated increased urinary NTx and calcium excretion, indicative of bone hyperresorption, and suppressed PTH and 1,25-D levels as early as 9 days post-SCI. Combined calcitriol-pamidronate therapy decreased urinary NTx and calcium excretion by 71% (P < .001) and 73% (P < .001), respectively. This therapy also increased serum levels of PTH (P <.05) and 1,25-D (P < .005). Post-pamidronate hypocalcemia or hypophosphatemia was observed in 44% (P < .01) or 53% (P < .01), respectively. CONCLUSION: Combined calcitriol-pamidronate therapy significantly inhibited bone hyperresorption in SCI patients.

Administration, Oral↗

PubMed2001

Rearrangement in the coding region of the MYCN gene in a subset of amplicons in a case of neuroblastoma with MYCN amplification.

The MYCN gene is often amplified but rarely rearranged in neuroblastoma. We report, for the first time, a rearrangement within the MYCN coding region in a metastatic neuroblastoma in a 3-year-old boy with MYCN amplification in his primary tumor. The rearrangement occurred 46 nucleotides downstream from the ATG codon in exon 2 of MYCN. The amplification level of the rearranged copies of the MYCN gene was lower than that of the unrearranged copies of MYCN. These results indicate that the rearrangement occurred after initial MYCN gene amplification. Monochromosomal somatic cell hybrid mapping of the novel region fused to exon 2 of MYCN localized it to chromosome 2, suggesting that this rearrangement resulted from an interstitial deletion, presumably within the MYCN amplicon itself.

Abdominal Neoplasms↗

PubMed2001

Her-2/neu and breast cancer.

Breast cancer is the most common malignancy in women in the United States in the year 2000. The proto-oncogene Her-2/neu (c-erb-B2) has become an increasingly important prognostic and predictive factor in breast cancer. Overexpression/amplification of the Her-2/neu has been associated with a worse outcome in patients with breast cancer. Herceptin, a "humanized" murine monoclonal antibody directed against the extracellular domain of the Her-2/neu protein, is being used to treat breast cancer that overexpresses Her-2/neu. The status of Her-2/neu in the tumor has become a critical factor in the management strategy of a breast cancer patient. The objective of this article is to provide a comprehensive review of all aspects of Her-2/neu in breast cancer, including biology, prognostic and predictive value, targeted Herceptin therapy, and the laboratory testing of Her-2/neu.

Adenocarcinoma↗

PubMed2001

Control of spermatogenesis in mice by the cyclin D-dependent kinase inhibitors p18(Ink4c) and p19(Ink4d).

Male mice lacking both the Ink4c and Ink4d genes, which encode two inhibitors of D-type cyclin-dependent kinases (Cdks), are infertile, whereas female fecundity is unaffected. Both p18(Ink4c) and p19(Ink4d) are expressed in the seminiferous tubules of postnatal wild-type mice, being largely confined to postmitotic spermatocytes undergoing meiosis. Their combined loss is associated with the delayed exit of spermatogonia from the mitotic cell cycle, leading to the retarded appearance of meiotic cells that do not properly differentiate and instead undergo apoptosis at an increased frequency. As a result, mice lacking both Ink4c and Ink4d produce few mature sperm, and the residual spermatozoa have reduced motility and decreased viability. Whether or not Ink4d is present, animals lacking Ink4c develop hyperplasia of interstitial testicular Leydig cells, which produce reduced levels of testosterone. The anterior pituitary of fertile mice lacking Ink4c or infertile mice doubly deficient for Ink4c and Ink4d produces normal levels of luteinizing hormone (LH). Therefore, the failure of Leydig cells to produce testosterone is not secondary to defects in LH production, and reduced testosterone levels do not account for infertility in the doubly deficient strain. By contrast, Ink4d-null or double-null mice produce elevated levels of follicle-stimulating hormone (FSH). Because Ink4d-null mice are fertile, increased FSH production by the anterior pituitary is also unlikely to contribute to the sterility observed in Ink4c/Ink4d double-null males. Our data indicate that p18(Ink4c) and p19(Ink4d) are essential for male fertility. These two Cdk inhibitors collaborate in regulating spermatogenesis, helping to ensure mitotic exit and the normal meiotic maturation of spermatocytes.

Animals↗

PubMed2001

SOX10 is abnormally expressed in aganglionic bowel of Hirschsprung's disease infants.

BACKGROUND: The primary pathology of Hirschsprung's disease (HD) is a congenital absence of ganglion cells in the caudal most gut. The spastic aganglionic bowel is often innervated by a network of hypertrophied nerve fibres. Recently, mutations of SOX10 have been identified in patients with HD but only in those with Waardenburg-Shah syndrome. AIMS: To understand the molecular basis for the pathogenesis of HD we intended to determine the specific cell lineages in the enteric nervous system which normally express SOX10 but are affected in disease conditions. METHODS: We studied colon biopsies from 10 non-syndromic HD patients, aged three months to four years, and 10 age matched patients without HD as normal controls. The absence of mutation in the SOX10 gene of HD patients was confirmed by DNA sequencing. Expression and cellular distribution of SOX10 in bowel segments of normal and HD infants were examined by reverse transcription-polymerase chain reaction and in situ hybridisation. RESULTS: We found that in normal infants and normoganglionic bowel segments of HD patients, SOX10 was expressed in both neurones and glia of the enteric plexuses and in the nerves among the musculature in normal colon. In the aganglionic bowel segments of patients, SOX10 expression was consistently lower and was found to be associated with the hypertrophic nerve trunks in the muscle and extrinsic nerves in the serosa. CONCLUSION: We conclude that SOX10 is normally required postnatally in the functional maintenance of the entire enteric nervous system, including neurones and glia. In non-syndromic HD patients who do not have the SOX10 mutation, the SOX10 gene expressed in the sacral region may be involved in the pathogenesis of the abnormal nerve trunks through interaction with other factors.

Case-Control Studies↗

PubMed2001

Caspase inhibitors attenuate oxyhemoglobin-induced apoptosis in endothelial cells.

BACKGROUND AND PURPOSE: Our recent study showed that oxyhemoglobin (OxyHb) induces apoptosis in cultured endothelial cells. Apoptosis requires the action of various classes of proteases, including a family of cysteine proteases known collectively as the caspases. This study was undertaken to investigate the effect of 2 caspase inhibitors, Z-VDVAD-FMK and Z-DEVD-FMK, in the protection of endothelial cells from OxyHb-induced apoptosis. METHODS: Cultured bovine brain microvascular endothelial cells (passages 5 to 9) were exposed to OxyHb (10 micromol/L) for 24 to 72 hours with and without caspase inhibitors. Cell attachment, DNA ladder, Western blotting of poly(ADP-ribose) polymerase (PARP), and caspase activities were measured to confirm the cytotoxic effect of OxyHb and the protective effect of the caspase inhibitors. RESULTS: (1) OxyHb produced cell detachment in a time-dependent manner. (2) OxyHb increased caspase-2 and -3 activities, produced DNA ladders, and cleaved PARP in endothelial cells. (3) Z-VDVAD-FMK and Z-DEVD-FMK (100 micromol/L) attenuated OxyHb-induced cell detachment, reduced caspase-2 and -3 activities, abolished OxyHb-induced DNA ladders, and prevented OxyHb-induced cleavage of PARP. CONCLUSIONS: OxyHb activates caspase-2 and -3 in cultured brain microvessel endothelial cells. Caspase inhibitors attenuated the cytotoxic effect of OxyHb.

Animals↗

PubMed2001

Farnesyl hydroxybenzoic acid derivatives from Ferula kuhistanica.

Four new farnesyl hydroxybenzoic acid derivatives, kuhistanols E-H (1-4), were isolated from the roots of the Uzbekistan medicinal plant Ferula kuhistanica. The structures of the new compounds were elucidated based on spectroscopic and chemical evidence.

Apiaceae↗

PubMed2001

Construction of recombinant vaccinia viruses using PUV-inactivated virus as a helper.

Recombinant vaccinia viruses (VVs) are widely used as expression vectors in molecular biology and immunology and are now under evaluation for gene therapy. The current techniques for inserting foreign DNA into the large VV genome are based on either homologous recombination between transfer plasmids and VVgenomes or direct DNA ligation and packaging using replication-deficient poxviruses. Here, we describe efficient new versions of both methods that produce 90%-100% of the recombinant viruses. In the new homologous recombination method, VV DNA "arms" obtained by NotI digestion and intact transfer plasmids were used for co-transfection. In the direct DNA ligation method, foreign DNA was inserted into a unique NotI restriction site of the VVgenome. In both methods, the generation of recombinant viruses was carried out in cells infected with a non-replicating, psoralen-UV (PUV)-inactivated helper VV. The convenience of these new techniques is demonstrated by the construction of recombinant VVs that produce E. coli beta-galactosidase. An important feature of these strategies is that any VV strain can be used as a helper virus after PUV inactivation.

Blotting, Southern↗

PubMed2001

Synergistic effect of photodynamic therapy with hypericin in combination with hyperthermia on loss of clonogenicity of RIF-1 cells.

Hypericin is a natural photosensitizer produced in plants of the genus Hypericum. The compound exhibits a potent phototoxicity both in vitro and in vivo. In the present study we investigated the effect of hypericin-mediated PDT on hyperthermia (43 degrees C) in RIF-1 cell line. Our results demonstrated a synergistic effect on loss of cell clonogenicity when PDT exposure was followed immediately by hyperthermia. This synergistic effect was diminished by introducing an interval (at 37 degrees C) between the two treatments. Furthermore, it was found that combining PDT treatment with hyperthermia could significantly enhance the cell death by necrosis as indicated by morphological examination and significant loss of membrane integrity. Our data suggest that the common cell membrane damage by both PDT and hyperthermia is likely to be responsible for this synergistic effect.

Animals↗

PubMed2001

[The construction of rapid amplification of cDNA ends cDNA libraries from human fetal bone and joint].

OBJECTIVE: To construct rapid amplification cDNA ends(RACE) cDNA libraries from human fetal bone and joint and provide resources for isolation of bone- and joint-specific development-related genes. METHODS: Total RNA of bone and joint were extracted with the modified single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. The double-stranded end-blunted cDNA were synthesized using TaKaRa's cDNA synthesis kit and ligated to cassette adaptors. All of the cDNA molecules were amplified by a pair of common primers. RESULTS: A protocol for RACE cDNA library construction from bone and joint was established and two RACE cDNA libraries from human fetal bone and joint were successfully constructed. CONCLUSION: The protocol of RACE cDNA library construction from limited materials proved to be simple and efficient and the library was suitable for RACE to isolate tissue-specific genes.

Bone and Bones↗

PubMed2001

[Computer-assisted video-endoscopic endonasal surgery].

UNLABELLED: To make the surgical procedure safer and more precise in FESS, a non-invasive markerless computer-assisted system (CAS) is described for intra-operative navigation whenever the critical regions may be affected by surgical manipulation. PATIENTS AND METHODS: Twenty patients with benign diseases of the paranasal sinuses were treated by Computer Assisted Video-endoscopic surgery, between December 1997 and March 1998. For the determination of accuracy and reproducibility of the system, ten anatomical landmarks on each side of the paranasal sinuses were chosen and measured. All of these points were identified on the direct live video-endoscopy image and compared to those obtained with the Optical Digitizing System (Flashpoint 5000(R)), on axial, coronal and sagittal view. The Optical Localizer we used detects the position of the relative coordinates of two rigid bodies made of IR-LED's each, one rigid body is secured to the head' of the patient with a headset, so that patient motion can be tracked, and the second rigid body attached to the operating instrument, leading to direct localization of the tip of the instrument. We use a markerless, skin surface-based registration method, which has the advantage to avoid doing a second CT scan examination usually performed to process the position of the fiducial markers. We register the data from the patient's usual paranasal CT scan. RESULTS: Computer-assisted surgery does not increase significantly the duration of the operation. Our markerless skin surface points registration method is reliable enabling of the movements patient's head during the procedure. Computer assistance can be used in almost any type of endoscopic sinonasal procedure. We obtained a registration and calibration accuracy of less than 1.5 mm in 89.2% of cases. CONCLUSION: CAS enables the surgeon to have a more thorough understanding of the complicated anatomy of paranasal sinuses, and may be especially helpful in revision surgery when normal anatomic landmarks are lacking. Due to the passive optical technology (Passive Polaris(R)), we are continuing clinical studies in ENT surgery in order do improve the system and to simplify its current management.

Adult↗

PubMed2001

Photodynamic therapy with hypericin in a mouse P388 tumor model: vascular effects determine the efficacy.

Hypericin, a polycyclic quinone obtained from plants of the Hypericum genus, exhibits strong photodynamic antitumor effects. In the present study, PDT efficacy of hypericin under different conditions was compared in a P388 mouse tumor model. Plasma and tumor drug measurements and assessment of vascular damage by fluorescein dye exclusion were performed to determine the relative contributions of vascular effects and direct tumor cytotoxicity. Furthermore, the influence of modifying tumor oxygenation on PDT effect was also evaluated. Study of PDT efficacy and tissue distribution revealed that PDT efficacy was more dependent on plasma concentration than tumor drug level. Fluorescein dye exclusion indicated the complete microvascular occlusion in the tumor and surrounding skin immediately after effective PDT treatments, while only a limited vascular occulation was observed after non-effective PDT treatment. It was found that neither tumor hypoxia induced by hydralazine nor increasing tumor oxygenation achieved by nicotinamide could significantly affect the effectiveness of various PDT protocols. These results suggest that tumor vasculature damage might be the primary mechanism of hypericin-mediated PDT effect. The existence of this potent secondary vascular effect is likely to account for the inability of tumor oxygenation modifiers to affect tumor response after PDT with hypericin.

Animals↗

PubMed2001

[Effects of conjugated linoleic acid on the metastasis of mouse melanoma B16-MB].

In order to explore the effects of conjugated linoleic acid on tumor metastasis, the proliferation, gap junction intercellular communication (GJIC), adhesion to extracellular matrix, and metastasis cascades of tumor cells were imitated in cell culture. The results showed that 100 and 200 mumol/L conjugated linoleic acid could inhibit the proliferation and the adhesion of tumor cells to extracellular matrix, and could recover its gap junction intercellulor communication.

Animals↗

PubMed2001

[Polymorphism of MAO-B gene and NAD(P)H: quinone oxidoreductase gene in Parkinson's disease].

OBJECTIVE: To investigate whether Parkinson's disease(PD) is associated with genetic polymorphism of intron 13 of monoamine oxidase B(MAO-B) and NAD(P)H: quinone oxidoreductase(NQO1) gene cDNA 609C to T. METHODS: Association study was performed in 126 PD patients and 136 healthy control subjects matched for age, sex and origin. The NQO1 gene polymorphism was analyzed with the polymerase chain reaction-restriction fragment length polymorphism, the polymorphism of intron 13 of MAO-B was analyzed by allele- specific PCR. RESULTS: The allelic frequency of the mutant T allele of NQO1 gene was significantly higher in the PD patients as compared to the controls(P<0.05). The relative risk of suffering from PD increased (OR=3.8) in the individuals with T allelic genotype of NQO1 gene, and the odds ratio was as high as 5.7 when the individuals with A or AA genotype of MAO-B gene coexisted with the T allele genotype of NQO1 gene. CONCLUSION: The cDNA 609T allele of NQO1 gene might be a risk factor of PD, which could be associated with the genetic susceptibility of PD. The high activity A or AA genotype of MAO-B and the low activity genotype of NQO1 gene might have synergistic effect. When both genotypes coexist, the risk of suffering PD will be increased greatly.

Aged↗

PubMed2001

Familial aggregation of ankylosing spondylitis in Southern China.

OBJECTIVE: To study the familial aggregation of ankylosing spondylitis (AS) in southern China and to compare the clinical and laboratory characteristics between the probands and their first-degree relatives with AS. METHODS: On the basis of questionnaires to 473 patients with AS, 402 responded and 36 self-reported having first-degree relatives with symptoms related to spondyloarthropathies. All together, 144 of 150 first-degree relatives of these 36 probands were examined for clinical and radiographic characteristics. HLA typing for HLA-B27 was performed by standard microlymphocytotoxicity method. RESULTS: The disease duration of the 36 probands was 5.03 +/- 3.76 years (0.5-14 yrs). Forty seven first-degree relatives of the 36 probands were diagnosed as having AS. The prevalence of AS among the first-degree relatives of these 36 aggregated families was 31.3%. The overall prevalence of AS among the first-degree relatives in these 402 families was estimated to be 2.8%. The recurrence risk of the first-degree relatives within these aggregated families was 31.3%, suggesting an excess risk to them of 120.4, while it was 10.8 to the general families. The probands more often had peripheral arthritis and enthesopathies (p < 0.001 and p = 0.01, respectively) than the AS patients among the first-degree relatives. HLA-B27 was associated with development of AS in the probands and the patients among the first-degree relatives. CONCLUSION: Although familial aggregation of AS in southern China is uncommon in general, the recurrence risk of the first-degree relatives of AS probands within the aggregated families is extremely high, according to our study among hospital based patients. As the disease of the first-degree relatives is often mild and atypical, familial background analysis should be encouraged to assist early diagnosis.

Adolescent↗

PubMed2001

[Analysis on genetic polymorphism of 13 STR loci on chromosomes 11 and 19 in Chinese Hans].

OBJECTIVE: To analyze the genetic polymorphism of 8 STR loci on chromosome 11 and 5 STR loci on chromosome 19 in Chinese Hans. METHODS: Polymerase chain reaction-single strand length polymorphism(PCR-SSLP) was used to genotype 100 randomly selected individuals of the Han nationality at 8 STR loci(D11S1984, D11S1999, D11S1392, D11S1985, D11S2002, D11S1986, D11S4464 and D11S2359) on chromosome 11 and 5 STR loci(D19S247, D19S714, D19S433, D19S246, D19S254) on chromosome 19. RESULTS: Eight alleles and 26 genotypes, 9 alleles and 15 genotypes, 6 alleles and 16 genotypes, 12 alleles and 40 genotypes, 6 alleles and 19 genotypes, 12 alleles and 48 genotypes, 8 alleles and 20 genotypes, 7 alleles and 13 genotypes were observed at D11S1984, D11S1999, D11S1392, D11S1985, D11S2002, D11S1986, D11S4464 and D11S2359. The heterozygosities for the 8 STR loci were 87%, 68%, 73%, 92%, 71%, 86%, 75% and 71%, respectively. Ten alleles and 19 genotypes, 10 alleles and 26 genotypes, 10 alleles and 24 genotypes, 11 alleles and 29 genotypes, 8 alleles and 18 genotypes were observed at D19S247, D19S714, D19S433, D19S246, D19S254. The heterozygosities for the 5 STR loci were 63%, 82% 72%, 81% 74%, respectively. CONCLUSION: The distribution of allele frequencies of 8 STR loci on chromosome 11 and 5 STR loci on chromosome 19 was consistent with the Hardy-Weinberg equilibrium and the highly genetic polymorphism was observed in Chinese Han population.

China↗