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Biomedical subjects

A King

Publications and source records attributed to A King.

At least 19 recordsLinked to original sources
PubMed1996

Evidence for the expression of HLAA-C class I mRNA and protein by human first trimester trophoblast.

In this study, evidence is provided that normal human first trimester extravillous trophoblast expresses class I HLA-C molecules in addition to HLA-G. cDNA from highly purified trophoblast cells obtained by flow cytometric sorting was amplified by reverse-transcriptase PCR using HLA locus-specific primers. The identity of the product was confirmed by Southern blotting and hybridization by a second HLA-C-specific oligonucleotide. HLA-C mRNA was clearly demonstrated in all trophoblast samples as well as in JEG-3 and BeWo choriocarcinoma cells. JAR choriocarcinoma cells did not express HLA-C. The presence of HLA-C protein in extravillous trophoblast was investigated using a panel of Abs: L31 is specific for heavy chains of all HLA-C alleles; Q1/28 reacts with all HLA class I products except HLA-G; HC-10 has preferential reactivity with HLA-B and HLA-C heavy chains. We performed 35S metabolic and 125I surface labeling of normal first trimester trophoblast and found abundant HLA-C intracellularly together with low levels of expression of both the beta 2m-associated forms and free heavy chains on the surface. Flow cytometric analysis of normal trophoblast confirmed the expression of a class I HLA molecule distinct from HLA-G by positive reactivity with Q1/28. Immunohistologic studies of first trimester placenta and the implantation site clearly showed expression of HLA-C in all extravillous trophoblast populations. Our results demonstrate the presence of two HLA class I molecules, HLA-G and HLA-C, on the surface of extravillous trophoblast. These results have implications in understanding how maternal uterine lymphocytes, notably the abundant NK-like cells, might recognize the implanting placenta.

Base Sequence↗
PubMed1996

Perturbations in the surface structure of A22 Iraq foot-and-mouth disease virus accompanying coupled changes in host cell specificity and antigenicity.

BACKGROUND: Foot-and-mouth disease virus (FMDV) is an extremely infectious and antigenically diverse picornavirus of cloven-hoofed animals. Strains of the A22 subtype have been reported to change antigenically when adapted to different growth conditions. To investigate the structural basis of this phenomenon we have determined the structures of two variants of an A22 virus. RESULTS: The structures of monolayer- and suspension-cell-adapted A22 FMDV have been determined by X-ray crystallography. Picornaviruses comprise four capsid proteins, VP1-4. The major antigenic loop of the capsid protein VP1 is flexible in both variants of the A22 subtype but its overall disposition is distinct from that observed in other FMDV serotypes (O and C). A detailed structural comparison between A22 FMDV and a type O virus suggests that different conformations in a portion of the major antigenic loop of VP1 (the GH loop, which is also central to receptor attachment) result in distinct folds of the adjacent VP3 GH loop. Also, a single mutation (Glu82-->Gly) on the surface of VP2 in the suspension-cell-adapted virus appears to perturb the structure of the VP1 GH loop. CONCLUSION: The GH loop of VP1 is flexible in three serotypes of FMDV, suggesting that flexibility is important in both antigenic variability and structural communication with other regions of the virus capsid. Our results illustrate two instances of the propagation of structural perturbations across the virion surface: the change in the VP3 GH loop caused by the VP1 GH loop and the Glu82-->Gly change in VP2 which we believe perturbs the GH loop of VP1. In the latter case, the amplification of the sequence changes leads to differences, between the monolayer- and suspension-cell-adapted viruses, in host-cell interactions and antigenicity.

Antigens, Viral↗
PubMed1996

Radiofrequency ablation therapy of the posteroseptal accessory pathway.

Among 652 patients with Wolff-Parkinson-White syndrome who underwent radiofrequency ablation in this laboratory, 139 (21%) were found to have a total of 146 posteroseptal accessory pathways. Ablation was conducted by the regular transvenous or transaortic approach; ablation from cardiac venous structures was used only if regular approaches were unsuccessful. Of the 146 posteroseptal accessory pathways, 94 were successfully ablated from the left posteroseptal region and 45 from the right posteroseptal region. In 3, successful ablation of the accessory pathway required delivery of the current to the proximal coronary sinus, and in 1 it required delivery of the current to both the atrial and ventricular aspects of the tricuspid valve at the right posteroseptum. Thus, the accessory pathway was successfully ablated in 143 (98%) of 146 instances or in 136 (98%) patients. In 3 patients, ablation was unsuccessful despite delivery of current to the left posteroseptum, the right posteroseptum, the proximal coronary sinus, and the middle cardiac vein. Seventy-seven (57%) patients with an initial success, including 9 patients with resumed preexcitation or recurrence of paipitations, underwent a follow-up electro-physiologic study 90 +/- 72 days after ablation. Of these 9 patients, the initial successful ablation site was the right posteroseptum in 7 and the left posteroseptum in 2. The accessory pathways were ablated successfully by subsequent trials in 8 patients, whereas in 1 the accessory pathway was severely damaged. Thus radiofrequency ablation of posteroseptal accessory pathways can be achieved by the regular transvenous or transaortic approach; delivery of current to the coronary sinus or middle cardiac vein is unnecessary in most patients.

Adult↗
PubMed1996

Immunology of human implantation: an evolutionary perspective.

The concept of the fetus as an allograft, which has been much cherished by reproductive immunologists, is in need of re-appraisal. We speculate that the relationship between the allogeneic conceptus and mother is not governed by the laws of classical transplantation immunity. Instead, this relationship is more akin to the allorecognition system seen in invertebrates.

Animals↗
PubMed1996

Evaluation of oestrogen and progesterone receptor expression in uterine mucosal lymphocytes.

Expression of the oestrogen and progesterone receptors on uterine mucosal leukocytes has been examined by dual immunohistology. Neither the oestrogen receptor nor the progesterone receptor was expressed by lymphocytes, macrophages or the distinctive population of uterine natural killer (NK) cells. Although the accumulation and survival of these NK cells appears to be hormonally dependent, the effects must therefore be indirect.

Decidua↗
PubMed1996

Incidence of gastroesophageal reflux with whey- and casein-based formulas in infants and in children with severe neurological impairment.

Ten exclusively gastrostomy-fed, neurologically impaired children (4.5-14.5 years old) with gastroesophageal reflux were randomly assigned to receive feedings with either a casein- or a whey-based formula for 48 h each and then crossed over to the other formula. One 24-h pH probe study each was performed while being fed casein- and whey-based formula, respectively. There was a significant reduction in episodes and duration of gastroesophageal reflux while consuming the whey-based formula (p < 0.05). Whey-based feedings should be considered an additional tool in conjunction with other antireflux measures to treat gastroesophageal reflux more effectively in children with severe neurological impairment. A similar study was also conducted involving 14 infants (3-12 months old) with documented gastroesophageal reflux using 24-h pH probe monitoring while consuming a casein-based formula. The formula was changed to a whey-based formula and the pH probe study repeated within 3-5 days. Four infants showed improvement and the rest showed either deterioration (1/14) or comparable results (9/14). The reduction in the mean number of episodes or duration of gastroesophageal reflux with the whey-formula was not significantly different from that with the casein-based formula (p > 0.05). Based on these findings, generalized recommendations for the use of whey-based formula in infants with gastroesophageal reflux cannot be made.

Adolescent↗
PubMed1996

Thrombin activates the sarcolemmal Na(+)-H+ exchanger. Evidence for a receptor-mediated mechanism involving protein kinase C.

Thrombin can activate the plasma membrane Na(+)-H+ exchanger in a variety of noncardiac cells. We have studied (1) the effect of thrombin on the activity of the sarcolemmal Na(+)-H+ exchanger in freshly isolated quiescent ventricular myocytes from the adult rat heart and (2) the signaling mechanism(s) underlying any effect. Reverse-transcription polymerase chain reaction analysis revealed thrombin receptor mRNA expression in a myocyte-enriched cell preparation. As an index of Na(+)-H+ exchanger activity, acid efflux rates (JHS) were determined in single myocytes (n = 4 to 11 per group) loaded with the pH-sensitive fluoroprobe carboxy-seminaphthorhodafluor-1 after two consecutive intracellular acid pulses (induced by transient exposure to 20 mmol/L NH4Cl) in bicarbonate-free medium. At a pHi of 6.9, JH did not change significantly during the second pulse relative to the first in control cells. However, when the second pulse occurred in the presence of 0.2, 1, or 5 U/mL thrombin, JH increased by 30%, 62% (P < .05), and 87% (P < .05), respectively. A hexameric thrombin receptor-activating peptide (SFLLRN) mimicked the effect of thrombin and increased JH by 73% (P < .05) at 25 mumol/L. In contrast, an inactive control peptide (FLLRN) was without effect at 25 mumol/L. In cells pretreated with 100 nmol/L GF109203X or 5 mumol/L chelerythrine (protein kinase C inhibitors), neither 5 U/mL thrombin nor 25 mumol/L SFLLRN produced a significant increase in JH. In the presence of 10 mumol/L HOE-694 (a Na(+)-H+ exchanger inhibitor), pHi did not recover after an acid load, even during exposure to 5 U/mL thrombin or 25 mumol/L SFLLRN, confirming that the Na(+)-H+ exchanger was the primary acid efflux mechanism under the conditions used. Neither 5 U/mL thrombin nor 25 mumol/L SFLLRN affected resting pHi and Ca2+ or background acid loading. We conclude that (1) adult rat ventricular myocytes express a functional thrombin receptor, whose stimulation results in increased activity of the sarcolemmal Na(+)-H+ exchanger, and (2) this effect appears to occur through a protein kinase C-mediated mechanism.

Animals↗
PubMed1995

Structural comparison of two strains of foot-and-mouth disease virus subtype O1 and a laboratory antigenic variant, G67.

BACKGROUND: Foot-and-mouth disease viruses (FMDVs) are members of the picornavirus family and cause an economically important disease of cloven-hoofed animals. To understand the structural basis of antigenic variation in FMDV, we have determined the structures of two viruses closely related to strain O1BFS whose structure is known. RESULTS: The two new structure are, like O1BFS, both serotype O viruses. The first, O1 Kaüfbeuren (O1K), is a field isolate dating from an outbreak of FMD in Europe in the 1960s. The second, called G67, is a quadruple mutant of O1K, generated in the laboratory, that bears point mutations conferring resistance to neutralizing by monoclonal antibodies, specific for each of the four major antigenic sites defined previously. The availability of the three related virus structures permits a detailed analysis of the way amino acid substitutions influence antigenicity. Structural changes are seen to be limited, in general, to the substituted side chain. For example, the GH loop of VP1, a highly antigenic and mobile protuberance which becomes ordered only under reducing conditions, was essentially indistinguishable in the three viruses despite the accumulation of up to four changes within its 15-residue sequence. At one of the other antigenic sites, however, changes between the two field strains did perturb both side-chain and main-chain structures in the vicinity. CONCLUSIONS: The conservation of conformation of the GH loop of VP1 adds to the evidence implicating an integrin as the cellular receptor for FMDV, since this loop contains a conserved RGD (Arg-Gly-Asp) sequence structurally similar to the same tripeptide in some other integrin-binding proteins. Structural changes required for the virus to escape neutralization by monoclonal antibodies are generally small. The more extensive type of structural change exhibited by the field isolates probably reflects differing selective pressures operating in vivo and in vitro.

Amino Acid Sequence↗
PubMed1995

Accuracy of a saliva test for HIV antibody.

The accuracy of a saliva collection and testing protocol for determination of HIV-1 antibody status was assessed under realistic field conditions. The 1,256 study participants came from two lower-prevalence settings--a self-referral testing clinic (478) and a street-based outreach program (431)--and two high-prevalence clinics--an HIV/AIDS treatment clinic (337) and a hemophilia clinic (10). Saliva was collected using the Omni-Sal collection device and was tested by technicians blind to serum status using a modified protocol that employed the Recombigen HIV-1 EIA. Serum was tested using standard methods. A single saliva enzyme immunoassay (EIA) correctly identified 358 of 368 seropositive individuals, for a sensitivity of 97.3% (95% CI: 95.1%-98.7), and 888 of 888 seronegative individuals, for a specificity of 100% (95% CI: 99.6-100). Confirmation of saliva EIA positives with a repeat saliva EIA and an in-house saliva radioimmunoprecipitation assay resulted in a substantial drop in sensitivity to 85.3% (95% CI: 81.0-89.0). We conclude that a single saliva EIA using the modified test protocol described is sufficiently accurate for surveillance purposes, but we do not recommend it for diagnostic purposes or screening.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Concurrent radiation therapy and chemotherapy in the treatment of primary squamous cell carcinoma of the vulva.

BACKGROUND: Interest in combined modality treatment and in quality of life issues may affect the choice of radical vulvectomy as the treatment of choice in many vulvar carcinomas. To evaluate the potential role of combined radiation and chemotherapy with or without local excision as primary treatment for squamous cell carcinoma of the vulva, the outccomes of 19 patients with this disease treated with combination therapy were reviewed. METHODS: Nineteen patients were treated between September 1987 and October 1992. Fifteen patients had American Joint Committee on Cancer Stage III disease; 4 had Stage II. All had clinically negative inguinal lymph nodes with the exception of two patients who had positive ipsilateral inguinal nodes that were removed before treatment. The patients received 45-50 Gy to the pelvis and inguinal nodes with concurrent chemotherapy that consisted of 5-fluorouracil given as a 96-hour continuous infusion (1000 mg/m2/d) during weeks 1 and 5 of radiation. A single dose of mitomycin-C (10 mg/m2) during the first day of chemotherapy has been used since November 1991. Ten patients were boosted with implants or electrons and 6 others underwent local excision. RESULTS: The median follow-up was 34 months. Responses were determined clinically 1 month after completion of the radiation and chemotherapy. Clinically, complete responses were obtained in 10 patients (53%), partial responses in 7 (37%), and no response in 1; 1 patient progressed during treatment. The combined modality therapy (radiation/chemotherapy/with or without wide local excision) resulted in a local control rate of 74% (14/19). All five treatment failures occurred within 6 months of treatment. Four of these patients were rendered disease free by radical vulvectomy and/or exenteration, for an overall local control rate of 95% (18/19). CONCLUSION: Concurrent radiation therapy and chemotherapy with local excision performed as needed, appears to be a reasonable alternative to radical vulvectomy in patients with primary squamous cell carcinoma of the vulva. Radical surgery remains a viable option for patients in whom primary therapy has failed.

Adult↗
PubMed1995

The role of integrins in adhesion of decidual NK cells to extracellular matrix and decidual stromal cells.

At the time of implantation, the decidua is infiltrated by a unique population of NK cells with large granular lymphocyte morphology, which are thought to influence placental trophoblast invasion and differentiation. The mechanisms used by these cells to migrate within decidua are not known, but in other biological processes such as wound healing and tumor invasion cell-matrix interactions are important. These interactions are mediated by specific receptors, mostly belonging to the family of integrins. Decidual NK cells are observed to bind to type IV collagen and fibronectin, but not to laminin. Adhesion to collagen was inhibited with an anti-alpha 1 integrin subunit mAb, whereas adhesion to fibronectin was blocked with anti-alpha 4, -alpha 5, and -beta 1 integrin subunit mAbs. Binding of decidual NK cells to decidual stromal cells was partially blocked with mAbs to the alpha 4 and alpha 5 integrin subunits. These results provide insight into the possible mechanisms utilized by decidual NK cells for migration and retention within the pregnant uterine mucosa.

3T3 Cells↗
PubMed1995

Screening for cytokine mRNA in human villous and extravillous trophoblasts using the reverse-transcriptase polymerase chain reaction (RT-PCR).

During the process of placental implantation, sessile villous trophoblast cells migrate from the villi into the decidua as isolated motile extravillous trophoblast cells. There is differential expression of the epidermal growth factor-receptor (EGF-R) and c-erbB2 proteins on villous and extravillous trophoblast populations. Using monoclonal antibodies to EGF-R and c-erbB2, we have obtained highly purified populations of villous and extravillous trophoblast by fluorescence activated cell sorting. These cells were examined by the reverse transcriptase-polymerase chain reaction (RT-PCR) using nested internal primer pairs for the following cytokines: CSF-1, GM-CSF, TNF-alpha, TGF-beta1, IFN-gamma, IL-2, LIF and also for LIF-receptor. TNF-alpha and TGF-beta 1 were present in all trophoblast populations. GM-CSF and CSF-1 were only found in some samples, with preferential expression of CSF-1 in villous populations. IFN-gamma, IL-2 and LIF mRNA were not found, although all samples contained LIF-receptor mRNA. These cytokines (CSF-1, TGF-beta, TNF-alpha and GM-CSF) are likely to influence trophoblast growth and differentiation in an autocrine manner, since their receptors are also present on trophoblast. These results illustrate a quick and simple method to analyse for the presence of cytokine and other transcripts in trophoblast subpopulations during early pregnancy.

Base Sequence↗
PubMed1995

Blastocysts exhibit preferential uptake of DNA fragments from the E6-E7 conserved region of the human papillomavirus.

The objective of the study was to determine if embryos at the blastocyst stage differentially took up exogenous human papillomavirus (HPV) DNA derived from the different HPV types and to determine whether the capture process was active or passive. In vivo fertilized mouse embryos were cultured to the blastocyst stage in vitro. The mouse blastocysts were incubated for 2 hr in the presence of a mixture of exogenous DNA fragments derived from HPV types 6b, 11, 16, and 18. The blastocysts were rigorously washed and analyzed for differential uptake of HPV gene sequences using the polymerase chain reaction (PCR) and polyacrylamide gel electrophoresis. PCR analysis detected HPV type 18 in only 40% of the blastocyst groups while detecting the other HPV types in 100% of the blastocysts. The negative control group did not show HPV DNA after PCR ruling out possible PCR artifacts. Formalin-fixed blastocysts also showed uptake of HPV DNA. In conclusion, the data suggest a role for embryos as passive vectors for foreign DNA and that the degree of DNA uptake varies with different types of HPV DNA.

Absorption↗
PubMed1995

Cyclophosphamide induced remission in relapsed, progressive idiopathic orbital inflammation ('Pseudotumour').

A patient with orbital pseudotumour with intracranial extension is reported. At presentation, the disease was confined to the orbit. Steroid therapy and orbital irradiation failed to control the condition, which then extended intracranially. Progression continued in spite of further treatment with cranial irradiation and azathioprine. Cyclophosphamide was introduced, which produced a dramatic clinical response with marked radiological improvement within a few months. This was maintained over 2 years.

Administration, Oral↗