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Biomedical subjects

K Smith

Publications and source records attributed to K Smith.

At least 19 recordsLinked to original sources
PubMed1996

Compartment switching of WNT-2 expression in human breast tumors.

WNT-2 is a secreted polypeptide with mitogenic effects in murine mammary epithelial cells, but its role in human cancer is unknown. Using RNase protection analysis of primary cell preparations and in situ hybridization analysis, we report that WNT-2 is expressed at low levels in normal human breast fibroblasts but not in epithelial cells. WNT-2 was found to be expressed at high levels in both the epithelium and stroma of 5 of 11 infiltrating carcinomas and 2 of 6 fibroadenomas. The high level of WNT-2 expression in tumor epithelium suggests that tumorigenesis may involve the ectopic expression of WNT-2 and the creation of an autocrine Wnt signaling loop.

Breast↗
PubMed1996

Ancient single origin for Malagasy primates.

We report new evidence that bears decisively on a long-standing controversy in primate systematics. DNA sequence data for the complete cytochrome b gene, combined with an expanded morphological data set, confirm the results of a previous study and again indicate that all extant Malagasy lemurs originated from a single common ancestor. These results, as well as those from other genetic studies, call for a revision of primate classifications in which the dwarf and mouse lemurs are placed within the Afro-Asian lorisiforms. The phylogenetic results, in agreement with paleocontinental data, indicate an African origin for the common ancestor of lemurs and lorises (the Strepsirrhini). The molecular data further suggest the surprising conclusion that lemurs began evolving independently by the early Eocene at the latest. This indicates that the Malagasy primate lineage is more ancient than generally thought and places the split between the two strepsirrhine lineages well before the appearance of known Eocene fossil primates. We conclude that primate origins were marked by rapid speciation and diversification sometime before the late Paleocene.

Animals↗
PubMed1996

The benefits of a shared-care prostate clinic.

OBJECTIVE: To establish a hospital based shared-care clinic to investigate and manage benign prostatic hyperplasia (BPH) with general practitioners (GPs). PATIENTS AND METHODS: During one year, 330 patients referred with suspected prostatic obstruction were investigated in an outreach clinic in a rural cottage hospital by urology department nurses according to a protocol. After this, they were referred directly back to their GPs with recommendations for their management or seen in the urologist's clinic. A questionnaire was completed by the GPs to assess their satisfaction with and attitudes to the clinic. RESULTS: One-third of the patients were referred directly back to their GP, a third were seen routinely and a third seen urgently in the urologist's clinic, usually because a prostate-specific antigen assay indicated the possibility of latent prostatic cancer. A survey confirmed that GP support for the clinic was unanimous whilst patients were reassured by the thoroughness and sensitivity of the clinic's nursing staff. CONCLUSION: The clinic reduced the workload of the GPs and urologists whilst providing a speedy and comprehensive assessment of patients presenting with suspected prostatic obstruction.

Clinical Protocols↗
PubMed1996

Titanium aneurysm clips: Part II--Seizure and electroencephalographic studies in implanted rabbits.

Because titanium is widely used in neurosurgical procedures, we compared spontaneous and induced epileptiform activity in 12 rabbits with titanium clips implanted in the subarachnoid space with 12 rabbits with cobalt alloy clips and 6 rabbits that were not operated on that served as controls. Beginning 1 week after surgery, 30-minute electroencephalographic recordings were made at monthly intervals for 6 months. Recordings were scored by an electroencephalographer unaware of which treatment group was being recorded. In 48 recordings made during 6 months, no epileptiform activity was observed in any animal. Seizure threshold was evaluated by continuous intravenous injection of the convulsant drug, pentylenetetrazole (2 mg/kg/min), with continuous electroencephalographic recording. Time to spiking for the nonsurgical control group was 327 mean seconds +/- 181 standard deviation (SD), 216 mean seconds +/- 135 SD for the titanium group, and 389 mean seconds +/- 290 SD for the cobalt group. There were no significant differences among the groups (P = 0.17). Latency to behavioral tonicoclonic seizure was 1031 seconds +/- 537 SD for the group not operated on, 875 seconds +/- 334 SD for the titanium group, and 1267 seconds +/- 764 SD for the cobalt group. This study suggests that titanium clips are well tolerated within the brain and will not induce seizures.

Animals↗
PubMed1996

A randomised trial comparing mesalazine and prednisolone foam enemas in patients with acute distal ulcerative colitis.

Distal ulcerative colitis can be treated with oral or rectal mesalazine, or both. A foam enema preparation has been developed and its efficacy investigated. The aim of this study was to evaluate the efficacy and safety of mesalazine foam enemas compared with prednisolone foam enemas in the treatment of patients with acute distal ulcerative colitis. Patients aged over 18 years presenting with a relapse of distal ulcerative colitis were randomly allocated treatment with mesalazine foam enema (n = 149 evaluable patients) and prednisolone foam enema (n = 146 evaluable patients) for four weeks. A randomised multicentre investigator blind parallel group trial was conducted. It was found that after four weeks of treatment, clinical remission was achieved by 52% of mesalazine treated patients and 31% of patients treated with prednisolone (p < 0.001). There was a trend in favour of more patients in the mesalazine group achieving sigmoidoscopic remission (40% v 31%, p = 0.10). Histological remission was achieved by 27% and 21% of patients receiving mesalazine and prednisolone respectively. Symptoms improved in both treatment groups. Significantly more mesalazine patients had no blood in their stools after four weeks of treatment (67% v 40%, p < 0.001). Prednisolone treated patients had significantly fewer days with liquid stools than mesalazine patients, with a median of 0 and 1 days respectively by week 4 (p = 0.001). In this study mesalazine foam enema was superior to prednisolone foam enema with regards to clinical remission, this was supported by favourable trends in sigmoidoscopic and histological remission rates. Both treatments were well tolerated.

Acute Disease↗
PubMed1996

Total hip and knee replacement treatment programs: a report using consensus.

Physical therapists may use varied treatment protocols for the acute care of patients with to hip or knee replacements. The purpose of this study was to develop, via consensus, a standardized treatment program for patients receiving total hip or knee replacement for primary osteoarthritis. Eighteen clinicians nationwide participated in a three-round consensus process. In Round 1, over 80% of the panel identified exercise, transfers, ambulation, and discharge criteria as the important treatment categories. In Round 2, they reviewed the preliminary physical therapy treatment program and recommended additional exercise regimes. In Round 3, 76% of the panel accepted the final total hip replacement program while 70% of the panel accepted the total knee replacement program. Using the consensus development process, physical therapists may begin to define their treatment programs which is fundamental to establishing a baseline standard of care.

Hip Prosthesis↗
PubMed1996

Coronary artery bypass graft surgery and its impact on erectile function: a preliminary retrospective study.

Erectile function is markedly affected by acute alterations in circulatory homeostasis of which coronary artery bypass graft surgery is an excellent model. A group of consecutive patients who had undergone coronary artery bypass surgery 6-12 months previously were selected for detailed review by questionnaires that scored their pre-operative and post-operative sexual function and erectile ability and aspects of the quality of life. Thirty patients were evaluable. 10 men (33.3%) had poor erectile function before surgery. Eleven out of 30 men reported an improvement in erectile function while 10 men experienced a decrease or cessation of erectile function. Four of the five patients reporting new post-operative erectile function had had good pre-operative function suggesting that the surgery was directly associated with the impotence in these men. This pilot study suggests that coronary artery bypass surgery can have a significant impact in erectile function.

Coronary Artery Bypass↗
PubMed1995

Glutathionylspermidine metabolism in Escherichia coli.

Intracellular levels of glutathione and glutathionylspermidine conjugates have been measured throughout the growth phases of Escherichia coli. Glutathionylspermidine was present in mid-log-phase cells, and under stationary and anaerobic growth conditions accounted for 80% of the total glutathione content. N1,N8-bis(glutathionyl)spermidine (trypanothione) was undetectable under all growth conditions. The catalytic constant kcat/Km of recombinant E. coli glutathione reductase for glutathionylspermidine disulphide was approx. 11,000-fold lower than that for glutathione disulphide. The much higher catalytic constant for the mixed disulphide of glutathione and glutathionylspermidine (11% that of GSSG), suggests a possible explanation for the low turnover of trypanothione disulphide by E. coli glutathione reductase, given the apparent lack of a specific glutathionylspermidine disulphide reductase in E. coli.

Amino Acid Sequence↗
PubMed1995

HLA-A2 subtypes are functionally distinct in peptide binding and presentation.

Nearly half of HLA-A2-positive individuals in African populations have a subtype of HLA-A2 other than the A*0201 allele. We have isolated the common African HLA-A2 subtype genes from Epstein-Barr virus-transformed B cell lines and have established stable class I reduced transfectants expressing these alleles. We have studied the peptide binding and presentation properties of A*0201, A*0202, A*0205, A*0214, and A*6901 by a combination of approaches: assaying direct binding of labeled synthetic peptides, studying the ability of antigen-specific cytotoxic T lymphocytes to recognize peptide-pulsed cells, and sequencing peptide pools and individual ligands eluted from cells. We find that A*0201-restricted peptides can also bind to A*0202 but do not bind strongly to the other alleles in this study. We show that some cytotoxic T lymphocytes can recognize all subtypes capable of binding an antigenic peptide, whereas others are subtype specific. Sequencing of eluted peptides reveals that A*0202 has a similar peptide motif to A*0201, but that A*0205, A*0214, and A*6901 have different motifs. These data strongly support a model in which residue 9 (Phe or Tyr) of the A2/A68/A69 molecules is a critical factor in determining the specificity of the B pocket of the major histocompatibility complex and the position 2 anchor residue of associated peptides. We conclude that a single-amino acid difference in the major histocompatibility complex can be sufficient to cause a dramatic change in the nature of bound peptides, implying that individuals with closely related HLA subtypes may present very different repertoires of antigenic peptides to T cells in an immune response. It is likely to be a general phenomenon that very similar class I subtypes will behave as functionally distinct HLA allotypes.

Alleles↗
PubMed1995

Genomic structure of an attenuated quasi species of HIV-1 from a blood transfusion donor and recipients.

A blood donor infected with human immunodeficiency virus-type 1 (HIV-1) and a cohort of six blood or blood product recipients infected from this donor remain free of HIV-1-related disease with stable and normal CD4 lymphocyte counts 10 to 14 years after infection. HIV-1 sequences from either virus isolates or patient peripheral blood mononuclear cells had similar deletions in the nef gene and in the region of overlap of nef and the U3 region of the long terminal repeat (LTR). Full-length sequencing of one isolate genome and amplification of selected HIV-1 genome regions from other cohort members revealed no other abnormalities of obvious functional significance. These data show that survival after HIV infection can be determined by the HIV genome and support the importance of nef or the U3 region of the LTR in determining the pathogenicity of HIV-1.

Adult↗
PubMed1995

Regulation of Wnt5a mRNA expression in human mammary epithelial cells by cell shape, confluence, and hepatocyte growth factor.

The Wnts are a family of genes with a role in cell fate and morphological development in numerous embryonic and adult tissues. In mouse mammary tissue a subset of the Wnts have a function in the normal development of the gland, and aberrant expression of Wnts normally silent in this tissue causes mammary carcinomas. We have previously shown that Wnt5a expression is elevated in the epithelial component of proliferative lesions of human breast and have therefore examined the regulation of Wnt5a mRNA expression in the human mammary epithelial cell line HB2, which has a luminal phenotype and thus represents the most commonly transformed cell type in human breast cancer. Wnt5a was up-regulated 30-fold at confluence. This up-regulation was induced specifically by confluence and not by the growth arrest that accompanied it. In addition, Wnt5a was down-regulated 3-fold by changes in cell shape associated with the transition from growth on a two-dimensional surface (flat cell morphology) to growth in three-dimensional gels (spherical cell morphology). Cytoskeletal disruption with non-toxic doses of colchicine also induced a spherical morphology and brought about a dose-dependent down-regulation of Wnt5a. Wnt5a was also down-regulated 10-fold during the hepatocyte growth factor-induced branching of HB2 cell aggregates in collagen gels. The down-regulation of Wnt5a preceded the branching process. A similar result was obtained with primary human breast epithelial populations and the breast cancer cell line MDA468. We conclude that regulation of Wnt5a expression is a down-stream effect of signaling by hepatocyte growth factor. These results are consistent with a role for Wnt5a in mammary epithelial cell motility and are in accord with Xwnt5a's function in embryonal cell migration. If Wnt5a's function in human mammary epithelial cells is similar to that of Xwnt5a, its up-regulation at confluence may be a mechanism for inhibition of cell migration beyond confluence.

Breast↗
PubMed1995

An investigation of methods for enriching trophoblast from maternal blood.

Trophoblast deportation is known to occur in normal human pregnancy, but it is not yet clear whether these cells routinely enter the maternal peripheral circulation and are available as a source of fetal DNA for non-invasive prenatal diagnosis of genetic disorders. To resolve this issue requires an efficient method of enriching trophoblast from maternal blood combined with a means to confirm its identity. Five different techniques were tested on ten retroplacental blood samples to determine the most sensitive and operator-efficient method. Lysis of red cells alone gave the best recovery of trophoblast but had to be discounted, together with Ficoll density gradient centrifugation, due to the very low purity and the excessive time required. Fluorescence-activated cell sorting (FACS) of pre-enriched trophoblast resulted in the lowest recovery rate (8 per cent) despite a 3250-fold enrichment and a very high purity. Immunomagnetic beads (Dynabeads) coated with anti-CD16 antibody proved to be the best method for the subsequent immunocytochemical characterization of deported trophoblast. However, IO beads coated with anti-CD45 antibody may be more useful for isolating trophoblast for prenatal diagnosis due to the high purity, enrichment (32-fold), and recovery rate (78 per cent) obtained with this method.

Cell Count↗
PubMed1995

Expression of messenger RNA for amphiregulin, heregulin, and cripto-1, three new members of the epidermal growth factor family, in human breast carcinomas.

The expression of amphiregulin (AR), heregulin (HRG), and cripto-1 (CR-1) mRNA transcripts was assessed in 60 human primary breast carcinoma. AR and HRG transcripts were expressed respectively in 58% and 25% of the carcinomas as measured by Northern blot analysis. CR-1 mRNA was found in 77% of the carcinomas using Reverse Transcriptase-PCR analysis. Coexpression of two or three of these peptides was observed in several specimens. There was no significant association between AR, HRG, and CR-1 expression and nodal status, EGF receptor, or c-erbB-2 protooncogene expression in these tumors. However, a significant association between AR expression and estrogen receptor positivity was observed.

Amphiregulin↗
PubMed1995

Plasmodium yoelii in mice: differential induction of cytokine gene expression during hyporesponsiveness induction and restimulation.

Acute Plasmodium yoelii murine malaria is associated with a marked depression of splenic T cell responses. The present study was undertaken to address the question if a defect in T cell proliferation results from a relative increase of a non-T cell population in the spleen or real biological changes occurring in T cells of the spleen after infection. When animals were acutely infected, the splenic cells responded poorly to cross-linked anti-CD3 mAb, Con A, and PWM stimulation. At this stage, a very limited array of cytokine was expressed. We failed to detect the transcripts for IL-2R p55, IL-2, IL-6, IL-10, and IFN-gamma in mice with acute P. yoelii malaria irrespective of the number of splenocytes subjected to RT-PCR. In contrast, late in the infection when mice cleared the parasites and became resistant to reinfection, mRNAs for the above cytokines as well as for IL-4, IL-5, GM-CSF, and TNF-alpha were detectable. During this late phase of infection, lymphocytes proliferated vigorously in response to TCR- and T cell mitogen-mediated stimulation. Surprisingly, during an early phase (as early as 3 days postinfection) with low parasitemia, before the establishment of T cell unresponsiveness, a broad array of cytokine expression including IL-2 and IFN-gamma expression as well as marked lymphoproliferative response upon T cell mitogen- and TCR-mediated stimulation was observed. When the expression of cytokine gene in freshly isolated (ex vivo) splenocytes from P. yoelii-infected animals was investigated, a similar pattern of cytokine profile was detected. We devised a methodology in which RNA from an increasing number of splenocytes (ranging from 1 to 16 million) was used to compensate for any difference in the frequency of splenic T cells between immune and acutely infected mice and to augment target molecules which could be measured simultaneously by PCR. The data presented in this study led us to speculate that "anergy" or relative increase of a non-T cell population cannot account solely for the T cell unresponsiveness in the acute phase of infection. We suggest that inactivation or/and ablation of reactive T cells may explain T cell hyporesponsiveness during acute malaria.

Animals↗