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Biomedical subjects

M Xia

Publications and source records attributed to M Xia.

At least 37 records · Page 2Linked to original sources
PubMed1998

Intercity spread of gonococci with decreased susceptibility to fluoroquinolones: a unique focus in the United States.

Patients and gonococcal isolates (n = 783) from five sexually transmitted disease clinics in Ohio and western Pennsylvania were studied to investigate the spread of gonococci with decreased fluoroquinolone susceptibility. Among patients with gonorrhea, rates of infection with strains with decreased fluoroquinolone susceptibility (MIC of 0.125-0.25 microg ciprofloxacin/mL) were 20% for Cleveland, 9% for Akron, 7% for Columbus, 1% for Toledo, and 0.5% for Pittsburgh. Persons infected with strains with decreased susceptibility were more likely than those with susceptible strains to be male and older; no significant differences in sex behaviors, residence of sex partners, or recent antibiotic use were detected. Prevalence of decreased susceptibility was not correlated with reported levels of community fluoroquinolone use. The Pro/IB-3 auxotype/serovar class accounted for 80% (44/55) of isolates with decreased susceptibility. Pro/IB-3 isolates from three cities had indistinguishable pulsed-field gel electrophoresis patterns, suggesting intercity spread of a clone.

Adult↗
PubMed1998

Rapid and inexpensive approaches to managing abnormal vaginal discharge or lower abdominal pain: an evaluation in women attending gynaecology and family planning clinics in Peru.

OBJECTIVES: To assess low abdominal pain, yellow vaginal discharge, other symptoms and signs, and demographic and behavioural variables as predictors for cervical or vaginal infection. METHODS: A cross sectional study of women attending gynaecology and family planning clinics in Lima, Peru was undertaken. 630 consecutive eligible female patients with chief or elicited complaints of yellow vaginal discharge, low abdominal pain, or both were interviewed and examined, together with a comparable reference group without these complaints. Vaginal specimens were tested for trichomoniasis and bacterial vaginosis. Endocervical specimens were tested for Neisseria gonorrhoeae and Chlamydia trachomatis using the ligase chain reaction. RESULTS: Infections found included chlamydial infection in 69 women (10.9%), gonorrhoea in 10 (1.6%), and either infection in 77 (12.2%); trichomoniasis in 46 (7.3%), bacterial vaginosis in 189 (30%), and either infection in 209 (33.2%). Cervical infection with C trachomatis and/or N gonorrhoeae was independently associated with history of a new sex partner within the last 3 months, more than one sex partner within the last year, use of condoms never or in less than 50% of sex acts, history of sex partner with STD within the last year; with symptoms of persistent low abdominal pain and of yellow vaginal discharge; and with signs of profuse and yellow vaginal discharge, cervical ectopy, easily induced endocervical bleeding, or brown cervical secretion. Using these findings, an algorithm was created that had a positive predictive value (PPV) of 36% for cervical infection among women reporting chief or elicited complaint of this abnormal vaginal discharge and a PPV of 25% among those without a complaint. A chief complaint of yellow vaginal discharge had a PPV of 50% for trichomoniasis or bacterial vaginosis. Among women without a chief complaint of yellow vaginal discharge, clinical findings of yellow vaginal discharge had a PPV of 55%. CONCLUSIONS: Where economic and technical constraints preclude testing, clinical findings and risk assessment are helpful in detecting vaginal and cervical infections. Several demographic, behavioural, clinical, and laboratory variables were predictive of infection in this population.

Abdominal Pain↗
PubMed1998

Reproductive tract infections in primary healthcare, family planning, and dermatovenereology clinics: evaluation of syndromic management in Morocco.

OBJECTIVE: To determine where and with what symptoms women seek care for reproductive tract infections (RTI) in Morocco and to guide allocation of resources for training and treatment for RTIs. METHODS: A primary healthcare centre (PHC), a family planning centre (FPC), and a specialty dermatovenereology clinic (SC) were selected in each of three urban areas. Women with symptoms of vaginal discharge, lower abdominal or pelvic pain, or genital lesions (genital ulcer or warts) underwent interviews, physical examinations, serological testing for human immunodeficiency virus (HIV) and syphilis, and collection of vaginal fluid for microscopic examination, and urine for detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) by ligase chain reaction (LCR). RESULTS: Over 8 months, 1238 women enrolled, including 61.8% at PHCs, 34.8% at FPCs, and 3.4% at SCs. Overall, 54% complained of vaginal discharge, of whom 8.8% had GC or CT infection and 30.1% had trichomoniasis (TV) or bacterial vaginosis (BV); 24.9% complained of lower abdominal pain with or without vaginal discharge, of whom 7.3% had GC or CT and 22.6% had TV or BV. GC or CT infections were found in 10.1% of PHC and 5.4% of FPC patients; while TV and/or BV infections were found in 28.7% and 22.8%, respectively. GC or CT infection was associated with perceived risk behaviours of the male partner (for example, belief partner is unfaithful) more often than with reported risk behaviours of the women themselves. For vaginal infections, a modified World Health Organisation (WHO) test algorithm for vaginal discharge involving risk assessment plus speculum and bimanual examination was 98.0% sensitive at PHCs and 90.8% at FPCs, with positive predictive value (PPV) of 33.4% at PHCs and 26.8% at FPCs. For GC or CT infections this algorithm was 60.6% sensitive at PHCs and 85.7% sensitive at FPCs; but PPV was only 9.9% and 9.0% respectively, little higher than the background prevalence of these infections. An RTI algorithm (Morocco specific) had comparable sensitivity and PPV for vaginal infection, and for cervical infection was less sensitive but had much higher PPV (26.9% for PHCs and 26.7% for FPCs). CONCLUSION: Women with complaints of vaginal discharge and/or lower abdominal pain presented to PHC and FP clinics, not to SCs. PHCs and FPCs should therefore receive resources for management of vaginal discharge. Both the test algorithm and the new RTI algorithm were useful in allocating treatment for vaginal infection, but only the RTI algorithm discriminated in selecting women with cervical infection. Even with the RTI algorithm, which limited treatment for cervical infection to risk assessment positive patients with signs of cervical infection or PID, the PPV for cervical infection was low, potentially resulting in frequent overtreatment and problems of partner notification.

Adolescent↗
PubMed1997

Neuronal expression of class II major histocompatibility complex (HLA-DR) in 2 cases of Pick disease.

BACKGROUND: Pick disease is a progressive form of dementia characterized by personality changes, speech disturbances, inattentiveness, and occasionally extrapyramidal phenomena. Although several variants have been recognized, the pathological profile of Pick disease includes focal frontotemporal atrophy, neuronal loss, astrocytosis, Pick bodies, and Pick cells. To date, little is known about the etiology of Pick disease. OBJECTIVE: To evaluate the possibility of inflammatory processes occurring in Pick disease pathophysiology. DESIGN: Immunohistochemistry for HLA-DR and related molecules was performed in brain tissue from individuals with Pick disease, Alzheimer disease, and diffuse Lewy body disease, as well as from neurologically normal controls. RESULTS: We report the unusual expression of the class II major histocompatibility complex protein Ia (HLA-DR) on neurons in 2 cases of Pick disease. In addition, both cases exhibited a dramatic microglial response. Neuronal HLA-DR immunostaining was not observed in 12 other cases of Pick disease or cases of Alzheimer disease, cases of diffuse Lewy body disease, or in control cases run con-currently. In addition, the pattern of HLA-DR staining observed in Pick disease was confirmed with another monoclonal antibody to HLA-DR. Frequent in vitro inducers of HLA-DR expression and enhanced class I major histocompatibility expression, interferon gamma, and tumor necrosis factor alpha were not detected. CD4-positive T lymphocytes were also not present and class I major histocompatibility complex expression was not detected on neurons or glia from brain tissue with Pick disease. CONCLUSIONS: These results are the first to demonstrate class II major histocompatibility complex expression on neurons. Based on these preliminary results, we suggest that some cases of Pick disease may be complicated by or involve in inflammatory process.

Aged↗
PubMed1997

Genomic homogeneity of the AHU/IA-1,2 phenotype of Neisseria gonorrhoeae during its disappearance from an urban population.

BACKGROUND: Isolates of Neisseria gonorrhoeae requiring arginine, hypoxanthine, and uracil (AHU) appeared in Denmark in 1946, were preponderant in Seattle during the 1970s, were associated with disseminated gonococcal infections (DGI), and were primarily of the IA-1,2 serovar. GOALS: To investigate the disappearance of the AHU/IA-1,2 phenotype and to examine by pulsed-field gel electrophoresis (PFGE) the genomic homogeneity of this unique phenotype isolated from Seattle-King County during the past decade. STUDY DESIGN: This retrospective study used data extracted from previous publications for the period 1971 through 1984, and from existing records at the Neisseria Reference Laboratory, University of Washington for the period 1985 through 1996. Samples (n = 68) of AHU/IA-1,2 isolates from 1984 to 1985 and 1988 to 1993 were analyzed using endonucleases NheI and XbaI. For comparison, 10 AHU/IB isolates were included in the study. RESULTS: AHU isolates, predominantly IA-1,2 strains accounted for 52% of the gonococcal isolates for the period 1971 through 1974, 40% for 1974 through 1976, 16% for 1984, and then declined from 7% in 1986 to 0% for each of the last 3 years, 1994 through 1996. Isolates with < or = 1 band difference after digestion with either NheI or XbaI were considered to belong to a single closely related pattern. Pulsed-field gel electrophoresis (PFGE) type designation was made from the combination of NheI and XbaI patterns. These criteria yielded 5 NheI and 8 XbaI PFGE patterns, and 11 PFGE types based on the combination of NheI and XbaI pattern. The most frequently occurring NheI and XbaI patterns accounted for 74% and 57% of isolates, respectively. One type persisted throughout the decade and accounted for 54% of the 68 isolates. Analysis of the 10 AHU/IB isolates yielded 7 NheI and 8 XbaI patterns that gave 9 types that were distinct from the types found in the AHU/IA-1,2 strains. CONCLUSION: The AHU/IA-1,2 phenotype first documented 50 years ago in Denmark still shows a high degree of genomic homogeneity during the past decade in Seattle. The implementation of screening, decreased rates of sexual exposure in the acquired immune deficiency syndrome era, or other factors may explain its apparent elimination in Seattle-King County.

Electrophoresis, Gel, Pulsed-Field↗
PubMed1997

[Volume loading experiment in dogs with large area infarction of right and left ventricles].

In order to study volume loading effect on large area myocardial infarction (MI) in right and left ventricles, large area MI in both ventricles and cardiogenic shock in 12 dogs were induced by occluding coronary arteries. Left ventricular systolic pressure (LVSP) and +/- dp/dt max. dropped markedly by 54%, 51% and 47% respectively, whereas right ventricular systolic pressure (RVSP) and +/- dp/dt max. fell by 9%, 25% and 27% respectively. The condition was obviously worse by rapid volume loading (dextran, 30 ml/kg, i.v. in 20 min.) in group I (n = 6), leading to increased retrograde beat of right ventricle, further decrease of +/- dp/dt max. in both ventricles, significant increase of right atrial pressure (RAP) and left ventricular and diastolic pressure (LEVDP) (2.9 +/- 0.2 kPa, P < 0.01 and 5.0 +/- 0.3 kPa, P < 0.001, respectively), and even ventricular fibrillation. Shock was reversed by combined treatment of dopamine (10 micrograms/kg.min) and glyceryl trinitrate (1 microgram/kg.min) in group II (n = 6) in 30 min, showing evident increase of arterial pressure, cardiac output, LVSP and +/- dp/dt max. without rise in RAP and LVEDP.

Animals↗
PubMed1997

[The development of an computerized analysis system for the women pelvic cavity impedance rheogram].

This article introduces the components and functions of an computered analysis system for the women pelvic cavity impedance rheogram. It can sample the pelvic cavity impedance rheogram signal of the body double-side and the reference ECG signal. With help of manual intervence, it also can automatically recognize characteristic points of the pelvic cavity impedance rheogram and measure the parameters. It can correct the recognized characteristic points simultaneously and print the pelvic cavity impedance rheogram of the body double-side and 15 characteristic data parameters. After clinical applying, the analysis results of mors 100 patients make clear that: this system has remarkably clinical significance for diagnosis of the women pelvic cavity extravasated blood and evaluation of treating effect, so it has much better clinical applied expectation.

Equipment Design↗
PubMed1997

Interleukin-8 receptor B immunoreactivity in brain and neuritic plaques of Alzheimer's disease.

Cytokines mediate inflammatory responses through their receptors in the hematopoietic system. In a search for potential mediators of inflammatory responses in Alzheimer's disease, we examined brain for cytokine receptors. Herein we describe interleukin-8 receptor B (IL-8RB, also termed CXCR2) immunoreactivity in the central nervous system. Strong IL-8RB immunoreactivity is present in both Alzheimer's disease and control brains. Neurons, dendrites, and axons are clearly immunoreactive. In Alzheimer's disease, IL-8RB immunoreactivity is also present in some swollen dystrophic neurites of neuritic plaques. Double staining and confocal microscopic analysis reveals that these IL-8RB-positive neurites in plaques are neurofilament positive and are distinct from astrocytic or microglial processes. In general, these IL-8RB-positive neurities do not co-localize with PHF-1 or AT8 (hyperphosphorylated tau) immunoreactive neurites but instead co-localize with beta PP-positive neurites. These results demonstrate for the first time IL-8RB immunoreactivity in the central nervous system and imply a new role for this receptor outside the hematopoietic system. The strong presence of IL-8RB on neurons and the potential of glial cells to produce IL-8 suggest that this system might mediate neuronal-glial interactions.

Adult↗
PubMed1997

Novel cyclic peptide agonist of high potency and selectivity for the type II vasoactive intestinal peptide receptor.

Ro 25-1392 [Ac-Glu8,OCH3-Tyr10,Lys12,Nle17,Ala19,A sp25,Leu26,-Lys27,28-vasoactive intestinal peptide(cyclo 21-25)] is a cyclic peptide analog of vasoactive intestinal peptide (VIP) that potently exerts cellular effects typical of VIP. The selectivity of Ro 25-1392 for type I (VIPR1) and type II (VIPR2) VIP receptors was investigated first in competitive binding studies using Chinese hamster ovary cell transfectants stably expressing recombinant human VIPR1 and VIPR2. Nonradioactive Ro 25-1392 was as potent a competitive inhibitor as VIP for the binding of 125I-VIP to VIPR2 transfectants (Ki = 9.6 +/- 1.0 and 16 +/- 1.7 nM, respectively; mean +/- S.E.M., n = 4). In contrast, Ro 25-1392 had a very low affinity for VIPR1, compared with VIP, and attained a maximum of only 40% mean inhibition of binding of 125I-VIP at 1 microM. The affinity of VIP (Ki = 3.4 +/- 1.5 nM, mean +/- S.E.M., n = 4) for binding to VIPR1 was 1000-fold greater than that of Ro 25-1392. Ro 25-1392 evoked concurrent and concentration-dependent increases in intracellular levels of calcium and cyclic AMP (EC50 = 3.0 +/- 0.4 nM, mean +/- S.E.M., n = 4) in VIPR2 transfectants, but not in VIPR1 transfectants. The VIP receptor specificity of Ro 25-1392 was confirmed by preincubation of Chinese hamster ovary transfectants with 0.1 microM Ro 25-1392 for 18 hr at 37 degrees C, to down-regulate each type of VIP receptor. Pretreatment of VIPR2 transfectants with Ro 25-1392 decreased Bmax by a mean of 58% and VIP-induced increases in the intracellular concentration of cyclic AMP by a mean of 65%. In contrast, there was no significant change in VIPR1 transfectants after pretreatment with Ro 25-1392. Ro 25-1392 thus is selectively recognized by VIPR2, with consequent initiation of cyclic AMP and Ca+2 signals and down-regulation of VIPR2. This potent analog of VIP may prove useful for investigations of VIPR2-mediated physiological effects of VIP and exploration of the roles of VIPR2 in diseases.

Animals↗
PubMed1996

Transduction of specific inhibition of HuT 78 human T cell chemotaxis by type I vasoactive intestinal peptide receptors.

The major immunoregulatory effects of vasoactive intestinal peptide (VIP) are mediated by structurally distinct types I (VIPR1) and II (VIPR2) G protein-associated receptors on some T cells, B cells, and macrophages. Identification of the separate immunologic activities of each type of VIPR has been complicated by the usual expression of only VIPR2 or of VIPR1 and VIPR2 together by most human T cells obtainable in sufficient number for functional analyses. The results of reverse-transcription PCR, Western blot, and [125I]VIP-binding studies have established that HuT 78 cultured human lymphoma T cells bear a mean of 75,000 VIPR1s per cell with a mean Kd of 3.3 nM, which transduce mean maximal increases in intracellular concentration of cAMP of 2.1-fold (ED50 = 72 nM), but no VIPR2s. HuT 78 T cells, in contrast to T cells that express VIPR2, did not respond to VIP by chemotaxis through micropore filters without or with a top layer of basement membrane-like Matrigel. Matrix metalloproteinase (MMP)-dependent in situ cleavage of [3H]type IV human collagen in the layer of Matrigel by HuT 78 T cells also was not stimulated by VIP. In contrast, IL-4 and TNF-alpha both stimulated HuT 78 T cell chemotaxis and in situ MMP activity at respective optimal concentrations ranging from 3 x 10(-10) M to 3 x 10(-9) M and 10(-10) M to 3 x 10(-10) M. VIP inhibited significantly HuT 78 T cell chemotaxis through Matrigel in response to both IL-4 and TNF-alpha, as a result of suppression of both chemotactic mobility, assessed by migration through micropore filters without Matrigel, and in situ MMP activity. The transduction of opposite effects of VIP on T cell migration through a model basement membrane by VIPR1 and VIPR2 suggests that the net chemotactic response of most T cells to VIP is determined by the VIPR2/VIPR1 ratio and that the predominant expression of VIPR1 would stabilize T cell populations in lymphoid follicles and tissue infiltrates.

Base Sequence↗
PubMed1996

Integrin-dependent role of human T cell matrix metalloproteinase activity in chemotaxis through a model basement membrane.

Human T lymphoblastoma cells of the CD4+ 8+ Tsup-1 line, that express alpha 4 and alpha 5 but not alpha 6 integrins of the beta 1 family, and CD4+ human blood T cells bind vasoactive intestinal peptide (VIP) with high affinity, leading to increased adherence, secretion of matrix metalloproteinases (MMPs), and chemotaxis. VIP-enhanced adherence of T cells to fibronectin was inhibited significantly by neutralizing monoclonal antibodies to beta 1 > alpha 4 > > alpha 5, but not to alpha 6. Antibodies to beta 1 and alpha 4 suppressed to a similarly significant extent VIP stimulation of both MMP-dependent T cell chemotaxis through fibronectin-enriched Matrigel and T cell degradation of 3H-type IV collagen in the Matrigel, without affecting VIP-evoked secretion of MMP by suspensions of T cells. The lesser inhibition of VIP-enhanced adherence of T cells to fibronectin by anti-alpha 5 antibody, than antibodies to beta 1 or alpha 4 chains, was associated with lesser or no suppression of MMP-dependent T cell chemotaxis through Matrigel and T cell degradation of type IV collagen in the Matrigel in response to VIP. Specific beta 1 integrins thus mediate interactions of stimulated T cells with basement membranes, including adherence, localized digestion by MMPs, and chemotactic passage, that promote entry of T cells into extravascular tissues.

Antibodies, Blocking↗
PubMed1996

Stimulus specificity of matrix metalloproteinase dependence of human T cell migration through a model basement membrane.

Chemotaxis of human T lymphoblastoma cells of the Tsup-1 line, which migrate similarly to blood T cells, through a layer of basement membrane-like Matrigel on a polycarbonate micropore filter was evoked by vasoactive intestinal peptide (VIP; concentration for a maximal response, 10(-7)M), IL-2 (10(-9)M), and the chemokines RANTES (10(-10)M) and macrophage inflammatory protein-1 alpha (10(-10)M). Chemotactic concentrations of each factor increased Tsup-1 cell secretion of matrix metalloproteinase-9 (MMP-9), with significant responses by 4 h for VIP, IL-2, and IL-4, but only after 24 h for macrophage inflammatory protein-1 alpha and RANTES, as quantified by Western blots and zymography. 3H-Labeled type IV human collagen incorporated in the Matrigel layer was degraded by migrating Tsup-1 cells, as assessed by release of radioactive fragments of the collagen. The in situ degradation of type IV collagen in Matrigel by migrating Tsup-1 cells was enhanced most significantly by VIP, IL-2, and IL-4 after 4 h at concentrations that increased the secretion of MMP-9 optimally, but only after 24 h by macrophage inflammatory protein-1 alpha and RANTES. The specific MMP inhibitor GM6001 suppressed Tsup-1 cell MMP activity evoked by all stimuli, as determined by zymography and in situ degradation of 3H-Labeled type IV human collagen. The chemotactic migration of Tsup-1 cells through Matrigel, but not through a filter alone, in response to optimal concentrations of VIP, IL-2, and IL-4, but not the chemokines, was inhibited by GM6001, with a concentration dependence similar to that for suppression of MMP activity. Thus elicitation of T cell chemotactic migration through a model basement membrane by stimuli that increase MMP activity early in the response depends on degradation of matrix proteins by MMP, whereas stimuli that recruit MMP late may rely on early activation of other proteases.

Basement Membrane↗
PubMed1996

Predominant expression of type II vasoactive intestinal peptide receptors by human T lymphoblastoma cells: transduction of both Ca2+ and cyclic AMP signals.

An immunoregulatory role for vasoactive intestinal peptide (VIP) is suggested by the high concentrations in subsets of neurons supplying lymphoid organs and by the capacity of VIP to affect T lymphocyte functions. The Tsup-1 line of human T lymphoblastoma cells expresses both type I and type II G protein-coupled VIP receptors (Rs), as shown by detection of the encoding mRNAs with reverse transcription-polymerase chain reaction analyses. Northern blot quantification of the relative amounts of mRNA encoding the two VIPRs in Tsup-1 cells indicated that type II predominates over type I, as it does in human blood CD4+ T cells. Tsup-1 cells bound 125I-VIP to 8.95 x 10(4) high-affinity sites/cell (Kd = 6.0 nM) and 7.45 x 10(5) low-affinity sites/cell (Kd = 210 nM). VIP increased [cAMP]i in Tsup-1 cells (EC50 = 14.4 nM) and stimulated a rapid and transient increase in [Ca2+]i (EC50 = 30 nM). Functional coupling of G proteins to type II VIPRs was suggested by the change in binding of 125I-VIP to Tsup-1 cell membranes from two sites with Kd values of 3.8 and 109 nM to one site of Kd 30 nM by GTP-gamma-S and the suppression by pertussis toxin of increases in [Ca2+]i evoked by VIP. The VIP antagonists, VIP4-28 and (4-Cl-D-Phe6-Leu17) VIP, inhibited 125I-VIP binding by type II VIPRs, as well as VIP-elicited increases in [Ca2+]i and [cAMP]i. Type II VIPRs thus are the major transducers of VIP signals to a subset of human T cells.

Amino Acid Sequence↗