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Biomedical subjects

A J Kelly

Publications and source records attributed to A J Kelly.

At least 37 records · Page 2Linked to original sources
PubMed2000

Endogenous and exogenous factors contributing to the surface expression of HLA B27 on mutant APC.

We have examined the expression of HLA B*2705 in the mutant cell line 721.220, which lacks endogenous HLA A and B alleles and expresses a defective tapasin molecule. Several peptide sensitive mAbs distinguish between HLA B*2705 expressed on the surface of 721.220 cells (B27.220) and 721.220 cells co-transfected with human tapasin (B27.220.hTsn). This differential staining defines subtle differences in the conformation of HLA B27, which most likely reflect changes in the repertoire of antigenic peptides bound to B27 in the presence and absence of wild type tapasin. HLA B27 molecules expressed on the surface of 721.220 display increased levels of "free" B27 heavy chain (HC-10 staining), an epitope that is dependent on TAP-translocated peptides. The conformation and stability of B27 molecules was examined by investigating the integrity of mAb epitopes and the half-lives of these complexes on cells cultured with and without serum. The decay of surface B27 epitopes occurred more rapidly in B27.220 and this effect was exaggerated in serum free media. Importantly, the decay of surface B27 molecules in B27.220.hTsn cells was characterized by an early increase in HC-10 staining when the cells were grown in serum free media. This decay of B27 molecules via HC-10 reactive intermediates was not observed in B27.220 cells, implying molecules on these cells may already have passed through this stage prior to surface expression. Taken together these observations indicate that tapasin has a significant contribution to the composition and stability of the B27-bound peptide repertoire.

Antigen-Presenting Cells↗
PubMed1998

Cell cycle-dependent transcriptional and proteolytic regulation of FtsZ in Caulobacter.

In the differentiating bacterium Caulobacter crescentus, the cell division initiation protein FtsZ is present in only one of the two cell types. Stalked cells initiate a new round of DNA replication immediately after cell division and contain FtsZ, whereas the progeny swarmer cells are unable to initiate DNA replication and do not contain FtsZ. We show that FtsZ expression is controlled by cell cycle-dependent transcription and proteolysis. Transcription of ftsZ is repressed in swarmer cells and is activated concurrently with the initiation of DNA replication. At the end of the DNA replication period, transcription of ftsZ decreases substantially. We show that the global cell cycle regulator CtrA is involved in the cell cycle control of ftsZ transcription. CtrA binds to a site that overlaps the ftsZ transcription start site. Removal of the CtrA-binding site results in transcription of the ftsZ promoter in swarmer cells. Decreasing the cellular concentration of CtrA increases ftsZ transcription and conversely, increasing the concentration of CtrA decreases ftsZ transcription. Because CtrA is present in swarmer cells, is degraded at the same time as ftsZ transcription begins, and reappears when ftsZ transcription decreases at the end of the cell cycle, we propose that CtrA is a repressor of ftsZ transcription. We show that proteolysis is an important determinant of cell type-specific distribution and cell cycle variation of FtsZ. FtsZ is stable when it is synthesized and assembles into the cytokinetic ring at the beginning of the cell cycle. After the initiation of cell division, the rate of FtsZ degradation increases as both the constriction site and the FtsZ ring decrease in diameter. When ftsZ is expressed constitutively from inducible promoters, the abundance of FtsZ still varies during the cell cycle. The coupling of transcription and proteolysis to cell division ensures that FtsZ is inherited only by the progeny cell that will begin DNA replication immediately after cell division.

Bacterial Proteins↗
PubMed1998

Ordered expression of ftsQA and ftsZ during the Caulobacter crescentus cell cycle.

The mechanisms by which bacterial cell division and DNA replication are co-ordinated are still unknown. We have used the easily synchronizable bacterium Caulobacter crescentus to determine when the cell division genes ftsQ and ftsA are transcribed during the DNA replication cycle and to compare their transcription with that of ftsZ. Unlike the situation in Escherichia coli, transcription of ftsQ and ftsA does not extend into ftsZ in Caulobacter. ftsQ and ftsA are co-transcribed by a strong promoter, P(QA), present within the end of the ddl gene upstream of ftsQ. Transcription of P(QA) is turned on at the end of the DNA replication period, coincident with the end of the ftsZ transcription period. ftsA is also transcribed by another promoter, P(A), present between ftsQ and ftsA. P(A) transcription is approximately 10 times weaker than P(QA) and occurs during the DNA replication period. Transcription of ftsA by P(A) is sufficient for cell viability, but is not sufficient for normal cell division. When the transcription of ftsA is increased constitutively, cell division is inhibited and stalks are synthesized at aberrant positions. Thus, transcription of ftsA and ftsZ mimics their order of action in Caulobacter and proper transcription of ftsA has to be maintained for normal cell division and differentiation.

Amino Acid Sequence↗
PubMed1998

Does early wound infection after elective orthopaedic surgery lead on to chronic sepsis?

Infection is an uncommon, but occasionally devastating, complication of orthopaedic surgery. The definition of post-operative infection remains problematic. A high rate of early post-operative sepsis has previously been reported using a clinical definition of wound infection as recommended by the Surgical Infection Study Group. The purposes of this study is to determine the rate of ongoing wound problems and deep sepsis 1 year after these early wound infections. Of 1131 consecutive orthopaedic procedures, there were 70 wound infections occurring within 30 days of surgery. Adequate follow-up data were obtained in 67 (97%) of the 69 patients alive at 1 year. Of these 67, three had definite evidence and two possible evidence of ongoing wound problems and/or deep sepsis. It is concluded that early post-operative wound infection as defined by the Surgical Infection Study Group is a poor predictor (4-10%) of ongoing wound problems and deep sepsis at 1 year. All of the confirmed cases of late sepsis were found to be associated with revision arthroplasty and/or pin tract sepsis.

Aged↗
PubMed1997

Is manipulation of moderately displaced Colles' fracture worthwhile? A prospective randomized trial.

Thirty elderly patients with moderately displaced Colles' fractures were randomly assigned to manipulation under Bier's block or plaster immobilization alone. Moderately displaced was defined as 10 degrees to 30 degrees of dorsal angulation and less than 5 mm of radial shortening compared with the uninjured side. The groups were well matched for age, sex, fracture type and displacement; immobilization time and rehabilitation were standardized. The outcome measures were: radiological position at union, the functional score of Gartland and Werley, grip strength, cosmesis and algodystrophy assessment. There was no detectable difference between the groups in any of the outcome measures. Two-thirds of the correction of dorsal angulation achieved by manipulation was lost by 5 weeks. We conclude that up to 30 degrees of dorsal angulation and 5 mm of radial shortening may be accepted in selected elderly patients.

Aged↗
PubMed1997

A novel high-dose chemotherapy protocol with autologous hematopoietic rescue in patients with metastatic breast cancer or recurrent non-Hodgkin's lymphoma.

In this phase II trial, we used a double dose-intensive chemotherapy and stem cell rescue protocol to treat breast cancer (BCA) patients or non-Hodgkin's lymphoma patients (NHL). The first cycle consisted of high-dose melphalan followed by ABMT. The second cycle used a novel chemotherapy combination; thiotepa, etoposide, carboplatin and cyclophosphamide (TECC) followed by ABMT. We treated 12 patients in total, nine with BCA, three with NHL. All nine BCA patients were treated with the two cycle protocol. The three NHL patients were treated with the second cycle only. Bone marrow (BM, 1 patient), peripheral blood stem cells (PBSC, 10 patients) or both (1 patient) were reinfused 60-72 h after completion of each cycle of chemotherapy. Recovery was rapid; the ANC rose to greater than 500/microl on day +11 (+8 to + 20) and the platelet count to greater than 20000/microl on day +12 (+6 to +20). The toxicities included the expected neutropenic fevers, severe mucositis, diarrhea, and a low incidence of mild renal insufficiency. No patients developed veno-occlusive disease, hemorrhagic cystitis or overt bleeding. With a mean follow-up of 37 months, 83.3% of the patients are alive. Six patients are in complete remission; one patient with BCA relapsed and expired; one patient with NHL is in CR now over 18 months after relapse and subsequent treatment with interferon; one patient is too early to evaluate. Progression-free survival overall is 75%, which is at least equivalent to many other recent studies using similar regimens. In addition, we have also found that delayed addition of G-CSF during the mobilization of PBSC was feasible and resulted in excellent CD34+ cell counts and engraftments, and reduced treatment costs. These results indicate that this chemotherapy is effective with good remission rates and high progression-free survival rates. It is also well tolerated with acceptable toxicities that are manageable. Long-term follow-up of a larger cohort of patients will be needed to ascertain the overall efficacy of this type of therapy.

Adult↗
PubMed1997

Absence of innervation of the uteroplacental arteries in normal and abnormal human pregnancies.

The spiral arteries of the human uterus are considerably remodeled structurally during pregnancy to facilitate an increase in blood flow. An immunohistochemical study was undertaken to determine whether the spiral arteries were innervated and, if so, whether they were denervated in the process of the physiologic vascular changes of normal pregnancy or, conversely, remained innervated in the absence of physiologic changes in abnormal pregnancy. Uterine tissues from nonpregnant nulliparous women, from normal early pregnancy, from normal late pregnancy, from abnormal early pregnancy (i.e. spontaneous abortions), and from abnormal late pregnancy (i.e. preeclampsia and intrauterine growth retardation) were subjected to immunohistochemistry using a panel of neuron-associated antibodies (neurofilament, neuron-specific enolase, S100 protein, protein gene product 9.5). All sections of the nonpregnant uterus showed an abundance of nerves deep in the myometrium, some of which were associated with radial and arcuate arteries. Very few nerves were demonstrated at the endomyometrial junction and no nerves were seen accompanying the intramyometrial spiral arteries. In both normal and abnormal pregnancy, nerves were not detected in the decidua or accompanying intradecidual spiral arteries, whether they were physiologically altered or not. Nerves were seen in the myometrium in 7 of 10 normal and in 1 of the 8 third-trimester abnormal placental beds, but none were seen accompanying intramyometrial spiral arteries, whether showing physiological changes or not. The lack of innervation of the spiral arteries in the nonpregnant state as well as in normal and abnormal pregnancy suggests that nonneurogenic mechanisms control blood flow at the spiral-arterial level.

Abortion, Spontaneous↗
PubMed1997

An anatomical study of a new portal for ankle arthroscopy.

We describe a medial midline portal between the tendons of extensor hallucis longus and tibialis anterior for arthroscopy of the ankle. We dissected 20 cadaver specimens to compare the risk of neurovascular injury using this approach with that of using standard arthroscopic portals. Compared with the anterocentral portal, the medial midline was a mean of 11.2 mm further from the nearest branch of the superficial peroneal nerve and 10.3 mm further from the dorsalis pedis artery. This portal allows good access to the joint surface and intra-articular structures and has a lower risk of injury to the dorsalis pedis artery, deep peroneal nerve or the medial branch of the superficial peroneal nerve.

Ankle Joint↗
PubMed1996

Poor reproducibility in radiographic grading of femoral cementing technique in total hip arthroplasty.

The first study of the reproducibility of a widely accepted grading system for femoral cementation in total hip arthroplasty is reported. Sixty postoperative radiographs were graded on two occasions at least 2 weeks apart by two experienced observers. The test-retest reproducibility rate was 60% for observer 1 and 70% for observer 2. The interobserver reproducibility varied between 60 and 63% for the different assessments. Between 5 and 6% of cases differed by more than one grade between tests. Kappa statistical analysis confirmed that reproducibility was poor in all cases. This cement grading system, even in the hands of experienced observers, has too high a rate of intraobserver and interobserver error to recommend its use.

Bone Cements↗
PubMed1996

An audit of early wound infection after elective orthopaedic surgery.

The incidence of early post-operative wound infection was studied prospectively in 1053 patients undergoing elective orthopaedic procedures over a 3-month period. The study was repeated in 1131 patients a year later, 6 months after the hospital had moved to new premises. A clinical definition of wound infection identified disturbingly high sepsis rates. A total of 44% of all infections occurred after discharge from hospital. Despite the large sample, there was no significant difference in the rate of early wound infection between the two periods (7.85 and 6.82%). There was no significant difference in infection rates between theatres with and without laminar air flow. In the majority (35 out of 53) of minor infections, bacteriological confirmation was not available because no microbiological specimens were received. Conversely, there were five negative swabs out of 16 wounds defined clinically as major infections. We conclude that, where the rate of bacteriological confirmation of wound infection is low, the use of a clinical definition gives higher audited sepsis rates. Large audit samples are required to demonstrate differences as a result of a changed practice.

Elective Surgical Procedures↗
PubMed1995

Characterization of a gene transcribed in the L2 and L3 layers of the tobacco shoot apical meristem.

Recent genetic and molecular studies have been initiated to uncover the fundamental cellular processes unique to the shoot apical meristem. Our previous work resulted in the isolation of a cDNA clone derived from tobacco apex RNA, A3, that appeared to be transcriptionally restricted to the shoot apex regardless of developmental stage. Here the DNA sequence and in situ RNA analysis of A3 is presented. The A3 gene potentially encodes a small hydrophilic polypeptide, the sequence of which is unique to current data bases. It has been found that transcripts of the A3 gene are confined to the subepidermal and internal cell layers of the tobacco shoot apical meristem throughout development, become localized to undifferentiated floral organ primordia, and diminish as the developmental potential of the meristematic tissue becomes restricted.

Amino Acid Sequence↗
PubMed1995

NFL, the tobacco homolog of FLORICAULA and LEAFY, is transcriptionally expressed in both vegetative and floral meristems.

The homologous genes FLORICAULA (FLO) of Antirrhinum and LEAFY (LFY) of Arabidopsis regulate the formation of determinate floral meristems. Transcripts of these single-copy genes are confined to floral meristems and some floral organs as well as to the leaflike bracts that subtend Antirrhinum flowers. Based on these observations, we hypothesized that the transcription of genes homologous to FLO and LFY in tobacco, a determinate plant in which the primary shoot apex is consumed in the production of a terminal flower, would serve as a molecular marker for floral commitment. Surprisingly, transcripts of the tobacco homologs NFL1 and NFL2 (Nicotiana FLO/LFY) were found not only in floral meristems, but also in indeterminate vegetative meristems. This implies that the transcriptional expression of the FLO/LFY homologous genes in the apical meristem is not sufficient for the initiation of floral meristem development. In addition, the transcript patterns of the NFL genes identified a previously undescribed subset of cells within the shoot apical meristem that may indicate unique functional compartmentalization. This suggests that, unlike FLO and LFY, which specify determinacy only during floral development, the NFL genes act to specify determinacy in the progenitor cells for both flowers and leaves.

Amino Acid Sequence↗
PubMed1994

Cloning and expression of a novel human brain inward rectifier potassium channel.

A complementary DNA encoding an inward rectifier K+ channel (HRK1) was isolated from human hippocampus using a 392-base pair cDNA (HHCMD37) as a probe. HRK1 shows sequence similarity to three recently cloned inwardly rectifying potassium channels (IRK1, GIRK1, and ROMK1, 60, 42, and 37%, respectively) and has a similar proposed topology of two membrane spanning domains that correspond to the inner core structure of voltage gated K+ channels. When HRK1 was expressed in Xenopus oocytes, large inward K+ currents were observed below the K+ reversal potential but very little outward K+ current was observed. In on-cell membrane patches, single channel conductance (g) was estimated to be 10 picosiemens by both direct measurement and noise analysis, in 102 mM external [K+]. HRK1 currents were blocked by external Ba2+ and Cs+ (K(0) = 183 microM, and K(-130) = 30 microM, respectively), and internal tetraethylammonium ion (K(0) = 62 microM), but were insensitive to external tetraethylammonium ion. The functional properties of HRK1 are very similar to those of glial cell inward rectifier K+ channels and HRK1 may represent a glial cell inward rectifier.

Amino Acid Sequence↗
PubMed1994

Low levels of amniotic fluid pregnancy specific beta-1-glycoprotein in Down's syndrome.

Amniotic fluid levels of beta-1-glycoprotein (SP1) were measured in 46 cases of Down's syndrome and compared with levels in 106 pregnancies of normal karyotype from 10 to 23 weeks of gestation. In normal pregnancies, levels rose from 87.5 iu/l at 10 weeks to a peak of 610.0 iu/l at 19 weeks of gestation. In cases of Down's syndrome, levels were reduced prior to 19 weeks of gestation (median multiple of the median, MoM = 0.75, P = 0.02). This effect was most marked prior to 16 weeks of gestation when the median multiple of the median (MoM) was 0.51 (P = 0.006). These data demonstrate that amniotic fluid levels of SP1 are low in Down's syndrome before 19 weeks of gestation.

Amniotic Fluid↗