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Biomedical subjects

R Hu

Publications and source records attributed to R Hu.

At least 109 records · Page 6Linked to original sources
PubMed1994

HIV-1 gp160 as a modifier of Th1 and Th2 cytokine response: gp160 suppresses interferon-gamma and interleukin-2 production concomitantly with enhanced interleukin-4 production in vitro.

Disease progression in HIV-1 infection is reported to be associated with a gradual shift in CD4+ T cell function from a Th type 1 to a Th type 2 of response, but the underlying mechanism remains unclear. In this study, the effect of HIV-1 envelope glycoprotein gp160 on secretion of cytokines IFN-gamma/IL-2 (Th1 type) and IL-4 (Th2 type) was analyzed using freshly isolated unfractioned peripheral blood mononuclear cells (PBMC), CD4+ T cell lines, and PBMC depleted of CD8+ cells (CD8- PBMC) as target cells. Pretreatment of these cells with HIV gp160 significantly reduced PHA-induced secretion of IFN-gamma and IL-2 but augmented IL-4 production. This effect of gp160 was not observed when the target cells consisted of PBMC depleted of either CD4+ cells (CD4- PBMC) or of CD2+ cells (CD2- PBMC). Pretreatment of gp160 with soluble CD4-immunoglobulin chimeric molecules abrogated the observed effects of gp160, suggesting that CD4-gp120 interaction is required for modification of the cytokine secretion profile. Our results suggest that exposure of CD4+ T cells to HIV-1 envelope proteins may modify the responses evoked by additional stimuli in favor of a Th2-type dominant response.

CD4-Positive T-Lymphocytes↗
PubMed1994

A comparative analysis of distraction rods versus Luque rods in thoracic spine fractures.

The findings of this study emphasize the importance of distraction in obtaining and maintaining reduction in upper thoracic fractures that are unstable and collapsing into kyphosis. It also shows that a Luque rectangle construct cannot fulfill this function adequately in this type of fracture. Thirty-four consecutive cases of surgically treated upper thoracic spine fractures were reviewed. Two patients died, and 4 were lost to follow-up, so after a minimum 6-month clinical and radiographic follow-up there were 11 patients in the Luque group and 17 in the distraction rod group. Preoperatively, there was no significant difference in age, sex, level of injury or severity of kyphosis between the two groups. The Luque stabilization took an average of 1 h longer. There was no difference in local, general or neurological complications between the groups. Pain at the final follow-up was the same according to analgesic use. The kyphosis in the Luque group increased progressively from preoperative to postoperative values continued and to increase. In the distraction rod group the postoperative kyphosis was improved compared with the preoperative values. At final follow-up the kyphosis had returned nearly to the preoperative values. The difference in the adequacy of the reduction as measured by percentage of anterior collapse between the two groups is highly statistically significant: distraction rod better postoperatively, P = 0.0114 (Student's t-test); distraction rod better at final follow-up, P = 0.0054 (Student's t-test).

Adult↗
PubMed1994

L-phenylalanine and UVA irradiation in the treatment of vitiligo.

In order to evaluate the efficacy of L-phenylalanine (L-Phe) in combination with UVA therapy for vitiligo an open trial (149 patients, 18 months) and a small double-blind trial (32 patients, 6 months) were conducted. Oral L-Phe loading resulted in peak plasma levels of L-Phe after 30-60 min and a slight increase in the plasma tyrosine level. Response to L-Phe plus UVA irradiation was positive, and various grades of repigmentation not exceeding 77% in the open and 60% in the blind trial were observed. An increased L-Phe dose resulted in increased L-Phe plasma levels but not in improved clinical results. The optimal L-Phe dose appears to be lower than 50 mg/kg/day. Although it is difficult to draw firm conclusions from the present investigation, we think that L-Phe may have a place in the treatment of vitiligo and its role merits further investigation.

Administration, Oral↗
PubMed1993

Pedicle morphology of the lower thoracic and lumbar spine in a Chinese population.

Knowledge of pedicle diameter and surface landmarks is crucial for safe placement of screws. Little attention has been paid to variations of entrance points for pedicle screws, differentiation of male and female pedicle sizes and pedicle size differences in nonwhite populations. Forty thoracolumbar spinal columns from T9 to L5 were measured using vernier calipers. Cephalad-caudad and medial-lateral diameter of the pedicle, length of the pedicle from posterior cortex to anterior cortex at the midline and parallel to midline was measured. Relation of the centre of the pedicle to the transverse process (TP) and to the superior facet joint was noted. Twenty-five male and 15 female specimens were measured. Average pedicle width in the female was 5.2 mm at T9 (SD 0.9) to 13 mm at L5 (SD 2.7) and in the male 6.0 mm at T9 (SD 1.1) to 12.8 mm at L5 (SD 2.7). Cephalad caudad diameter was 12.5 mm (SD 1.2) at T9 to 20.5 mm (SD 3.6) at L5 in the male and in the female 12.2 mm (SD 1.3) at T9 to 18.7 mm (SD 3.9) at L5. All specimens had starting points cephalad to the midpoint of the TP at T9. At L5, 37 of 40 specimens had starting points at the midpoint of the TP. Starting points were parallel to the middle or lateral third of the superior facet joint at T9. At L5 starting points were at least one third of the facet joint lateral to the lateral border of the facet. Female pedicle width was smaller than male at T9 (P = 0.03) and T12 (P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Asian People↗
PubMed1993

Evidence for multiple binding sites for several components of human lymphoblastoid interferon-alpha.

The antiproliferative and competitive binding activities of 20 purified components of human lymphoblastoid interferon (IFN)-alpha were compared with that of recombinant human IFN-alpha 2b on Daudi and AU937 cells. We observed broad ranges of antiproliferative activities of the IFN-alpha components on these cell lines. Daudi cells were more sensitive to the IFN-alpha components than AU937 cells; the concentrations of the components that resulted in 50% inhibition of cell growth ranged from 0.003 ng/ml to > 10 ng/ml on Daudi cells and 0.05 ng/ml to > 200 ng/ml on AU937 cells. Component o was the most active human IFN-alpha on both cell lines. Scatchard analysis demonstrated that the number of IFN-alpha 2b binding sites is greater on Daudi cells (12,700 binding sites/cell) than AU937 cells (3,300 binding sites/cell); however, their receptor affinities were similar. Component o, which exhibited high antiproliferative activity on both cell lines, had low affinity for the IFN-alpha 2b binding site on AU937 and Daudi cells. Several human IFN-alpha s (components b', b", and e) appeared to have high affinity binding sites but low antiproliferative activity on both Daudi and AU937 cells. These data suggest that there may be more than one binding site or receptor for human IFN-alpha, and/or there may be a multicomponent receptor involved in the biological actions of these molecules.

Binding Sites↗
PubMed1993

Occurrence and distribution in Rhode Island of Hunterellus hookeri (Hymenoptera: Encyrtidae), a wasp parasitoid of Ixodes dammini.

The wasp Hunterellus hookeri Howard parasitizes several species of ixodid ticks including Ixodes dammini Spielman, Clifford, Piesman & Corwin, the vector of Lyme disease spirochetes, Borrelia burgdorferi, in the northeastern United States. We detected the occurrence and evaluated the distribution of this wasp parasitoid in populations of I. dammini in Rhode Island. There has been no intentional introduction of a tick parasitoid recorded anywhere in Rhode Island; yet, we found this wasp at one of the six study sites (Prudence Island), where it parasitized 21 (n = 243) and 17% (n = 284) of nymphal I. dammini collected during 1988 and 1989, respectively. The proportion of nymphs parasitized was greatest during May (46%) and was less in June (18%), July (18%), and August (11%). In Rhode Island, the wasp was only found parasitizing ticks at the site with the highest (by a factor of 2) tick population, confirming similar observations in Massachusetts and New York. It is suggested that establishment as well as the distribution of H. hookeri depends upon a super abundant deer tick population. The usefulness of this parasitoid as a biological control agent is yet unknown.

Animals↗
PubMed1993

Anterior cervical corpectomy for the treatment of complex cervical lesions.

Instability and stenosis of the cervical spine have been treated by posterior decompression and anterior decompression with fusion. In this study the authors evaluate the results obtained in 31 patients who underwent anterior cervical corpectomy for compressive or unstable lesions of the cervical spine. Operative level, preoperative and postoperative symptoms and physical findings were assessed. Twenty-seven patients had preoperative neurologic symptoms and signs, including alterations in sensation, motor findings and reflexes. The average follow-up was 12 months, average number of disc spaces excised was 2.5 and average number of vertebral bodies excised was 1.6. With respect to relief of pain, results were good or excellent in 27 patients. All patients but one had union of the bone graft. No neurologic deterioration occurred. The authors believe that patients with compressive lesions of the cervical spine can benefit from anterior cervical corpectomy with fusion and that complications are minimal.

Adult↗
PubMed1992

Distribution of Ixodes dammini (Acari: Ixodidae) in residential lawns on Prudence Island, Rhode Island.

The distribution of nymphal Ixodes dammini Spielman, Clifford, Piesman & Corwin in residential lawns was assessed by flagging on Prudence Island, RI. The number of ticks per sample was five times greater in lawns adjacent to woods than in lawns adjacent to other lawns. Relative tick abundance was negatively correlated with distance from the woods, but the decline was gradual. Spirochete prevalence in ticks did not differ among lawn types or at different distances from the woods. Therefore, barriers that keep people away from the wood edge probably lower the risk of acquiring Lyme disease, but there is still a risk. Even with physical barriers at lawn-wood edges, personal precautions to prevent tick bites should be followed.

Animals↗
PubMed1992

HLA class II genes in Graves' disease.

Inheritance of Graves' disease has been linked to the HA-DR3 gene product which may function in some specific way in antigen presentation. To determine whether the first extracellular domain of this protein, which is specifically involved in antigen presentation, has the same sequence in patients with Graves' disease and in normal individuals, we have amplified the second exon using the polymerase chain reaction, and then cloned and sequenced the DNA segment. In eight subjects with Graves' disease, sequences identical to prototypic reported sequence for DRB1*0301 were recovered, and in two individuals sequences varied by a few nucleotides, leading to 1-3 amino acid substitutions which did not occur in a pattern. Sequences identical to the prototypic sequence known as DRB3*0101, also previously known as DRw52, were also recovered. Thus the HLA-DRB1 and B3 genes present in patients with autoimmune disease appear to be the same as those present in the general population. These observations indicate that a unique allele is not present in patients with autoimmune disease, but rather that the normal DR3 allele itself, in a manner yet to be described, increases the probability of developing autoimmune thyroid disease.

Amino Acid Sequence↗
PubMed1992

Drill sleeve for pedicle screw fixation.

Pedicle screw fixation is a popular method of fixation of the spine. Placement of screw and prevention of injury are surgeon dependent. We describe an easily made drill sleeve and depth gauge to assist in the preparation of the vertebral pedicle for pedicle screw application. Use of this device will help prevent soft tissue injury and overpenetration of the drill in the vertebral body.

Bone Screws↗
PubMed1991

Detection apparatus for multiple heterogeneous chemiluminescence immunoassay configurations.

We describe an apparatus for measuring signals emanated from two heterogeneous chemiluminescence immunoassay (CLIA) configurations: antibody-coated polystyrene beads, in reaction tray wells, and microparticles captured by a porous matrix. An optics and fluidics design which allows the use of a common detection head for these two different assay configurations is described. The detection head moves along three Cartesian coordinates to create a localized light-tight compartment around each individual disposable reaction vessel. Reproducibility of the light seal, trigger solution delivery, and mixing is achieved for acridinium-labeled CLIA. The coated polystyrene beads configuration is tested using beta HCG, CEA, and TSH assays. The microparticle-capture configuration is tested using beta HCG and HBsAg assays. The microparticle capture CLIA has shorter incubation times and the potential for ease of automation.

Data Interpretation, Statistical↗
PubMed1991

Improvement in the specificity of assays for detection of antibody to hepatitis B core antigen.

Reducing agents dramatically alter the specificity of competitive assays for antibody to hepatitis B core antigen (anti-HBc). A specificity improvement was demonstrated with a new assay which utilizes microparticle membrane capture and chemiluminescence detection as well as a current radioimmunoassay procedure (Corab: Abbott Laboratories, Abbott Park, Ill.). The effect was most noticeable with elevated negative and weakly reactive samples. In both systems, reductants increased separation of a negative population (n = 160) from assay cutoffs. With a selected population (n = 307), inclusion of reductant eliminated apparent anti-HBc activity in 54 of 81 samples in the 30 to 70% inhibition range. Reductant-stable anti-HBc samples were strongly associated with the presence of antibody to hepatitis B surface antigen (21 of 27). The association persisted below the detection limits of current assays to 0.3 to 0.4 Paul Ehrlich Institute units per ml. Only 1 of 54 reduction-sensitive borderline samples was confirmed to be positive for antibody to hepatitis B surface antigen. The modified procedures had unchanged or slightly improved sensitivity for immunoglobulin G (IgG)-associated anti-HBc activity. Although IgM anti-HBc detection was reduced from four- to eightfold in the presence of reductants, sensitivities remained at least twofold greater than tha of an enzyme immunoassay (Corzyme M; Abbott) designed to detect acute-phase levels of IgM anti-HBc. The use of reducing agents should significantly improve the reliability of anti-HBc testing, especially near assay cutoffs.

Binding, Competitive↗