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Biomedical subjects

A J Malcolm

Publications and source records attributed to A J Malcolm.

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

Mohs' surgery of periocular basal cell carcinoma using formalin-fixed sections and delayed closure.

Mohs' surgery of periocular basal cell carcinoma (BCC) ensures a high cure rate with maximal preservation of normal tissue. The formalin-fixed paraffin-embedded tissue technique allows Mohs' surgery to be performed using routine pathology facilities and permits the efficient use of operating room personnel and theatre time. The inevitable delay between excision and closure may potentially result in a poor functional and cosmetic outcome, particularly around the eye. We prospectively studied all patients with periocular BCC treated with this technique at our unit between 1985 and 1996. One hundred and twenty-three periocular BCCs in 120 patients were treated. Microscopic clearance was achieved in all cases. Closure was performed on average 5 days after the initial excisional stage. Closing procedures included direct closure, flaps and grafts. Significant complications affecting outcome were noted in only two patients. Eighty-eight per cent of patients assessed had a functional and cosmetic result regarded as excellent, good or adequate. Mohs' surgery of periocular BCC using formalin-fixed paraffin-embedded tissue and delayed closure results in a satisfactory functional and cosmetic outcome and offers a viable alternative to the frozen section fresh tissue technique.

Adult↗
PubMed1997

Randomised trial of two regimens of chemotherapy in operable osteosarcoma: a study of the European Osteosarcoma Intergroup.

BACKGROUND: A previous trial by the European Osteosarcoma Intergroup (EOI) suggested that a short intensive chemotherapy regimen with doxorubicin and cisplatin might produce survival of operable, non-metastatic osteosarcoma similar to that obtained with complex and longer-duration drug regimens based on the widely used T10 multi-drug protocol. We undertook a randomised multicentre trial to compare these two approaches. METHODS: 407 patients with operable, non-metastatic osteosarcoma were randomly assigned the two-drug regimen (six cycles [18 weeks] of doxorubicin 25 mg/m2 on days 1-3 and cisplatin 100 mg/m2 on day 1) or a multi-drug regimen (preoperatively vincristine, high-dose methotrexate, and doxorubicin; postoperatively bleomycin, cyclophosphamide, dactinomycin, vincristine, methotrexate, doxorubicin, and cisplatin; this protocol took 44 weeks). Surgery was scheduled for week 9 for the two-drug group and week 7 for the multi-drug group. Analyses of survival and progression-free survival were by intention to treat. FINDINGS: Of 407 randomised patients, 391 were eligible and have been followed up for at least 4 years (median 5-6 years). Toxic effects were qualitatively similar with the two regimens. However, 188 (94%) of 199 patients completed the six cycles of two-drug treatment, whereas only 97 (51%) of 192 completed 18 or more of the 20 cycles of the multi-drug regimen. The proportion showing a good histopathological response (> 90% tumour necrosis) to preoperative chemotherapy was about 29% with both regimens and was strongly predictive of survival. Overall survival was 65% at 3 years and 55% at 5 years in both groups (hazard ratio 0.94 [95% CI 0.69-1.27]). Progression-free survival at 5 years was 44% in both groups (hazard ratio 1.01 [0.77-1.33]). INTERPRETATION: We found no difference in survival between the two-drug and multi-drug regimens in operable, non-metastatic osteosarcoma. The two-drug regimen is shorter in duration and better tolerated, and is therefore the preferred treatment. However, 5-year survival is still unsatisfactory and new approaches to treatment, such as dose intensification, are needed to improve results.

Adolescent↗
PubMed1997

Apoptosis of N-type neuroblastoma cells after differentiation with 9-cis-retinoic acid and subsequent washout.

BACKGROUND: The overall survival rate for patients with neuroblastoma has improved over the past two decades, but long-term survival for the subgroup of patients with high-risk disease remains low. In recent years, there has been interest in the potential clinical use of drugs able to induce differentiation of neuroblastoma cells. Since 9-cis-retinoic acid induces better and more sustained differentiation of neuroblastoma in vitro than other retinoic acid isomers, this may be a more appropriate retinoid for use in neuroblastoma therapy. PURPOSE: The purpose of this work was to compare the long-term effects of all-trans- and 9-cis-retinoic acid on neuroblastoma differentiation using an N-type (neuroblastic) cell line, SH SY 5Y, as an in vitro model. In addition, we wanted to find out whether 9-cis-retinoic acid would induce programmed cell death (apoptosis) in these N-type neuroblastoma cells and to determine whether the effects of either 9-cis- or all-trans-retinoic acid are dependent on their continued presence in the culture medium. METHODS: SH SY 5Y cells were incubated in either the continued presence of all-trans- or 9-cis-retinoic acid or for 5 days with retinoic acid followed by culture in the absence of retinoid for up to 13 days. Morphologic changes were observed using phase-contrast and scanning electron microscopy. Apoptosis was determined by flow cytometry of propidium iodide-stained cells and by using terminal deoxynucleotidyl transferase to end-label DNA fragments in situ in apoptotic cells. RESULTS: Culture of SH SY 5Y cells with all-trans- or 9-cis retinoic acid for 5 days induced morphologic differentiation and inhibited cell growth. These effects were maintained in the continuous presence of each retinoic acid isomer but were more profound in cells treated with 9-cis-retinoic acid. The differentiation of cells treated with all-trans-retinoic acid was reversible once retinoic acid was removed from the medium. Conversely, apoptosis was induced in cells treated with 9-cis-retinoic acid for 5 days and cultured for 9 days (4 days after washout) but not in cells cultured in the continuous presence of 9-cis-retinoic acid. This effect was specific to 9-cis-retinoic acid. CONCLUSIONS: Previous studies have demonstrated differential responses to all-trans-retinoic acid in N- and S-type (substrate-adherent or Schwann-like) neuroblastoma cells: Apoptosis is induced in S-type cells, whereas differentiation occurs in N-type cells. The present results show that, unlike all-trans-retinoic acid, 9-cis-retinoic acid induces both differentiation and apoptosis in N-type SH SY 5Y neuroblastoma cells. However, apoptosis was dependent on removal of 9-cis-retinoic acid from the culture medium. IMPLICATIONS: Since both differentiation and apoptosis are involved in tumor regression, 9-cis-retinoic acid may be a more appropriate retinoid for clinical trials in neuroblastoma. The dependence of apoptosis on treatment and subsequent removal of 9-cis-retinoic acid implies that drug scheduling may be an important parameter affecting therapeutic efficacy.

Alitretinoin↗
PubMed1997

Fibrous dysplasia of bone: case report with autopsy study 80 years after the original clinical recognition of the bone lesions.

We present a report of the histological features of the bone lesions in a case of polyostotic fibrous dysplasia studied at autopsy in a patient aged 88 years. While much of the fibrous tissue of the lesions contained the trabeculae of non-lamellar bone that are a feature of fibrous dysplasia in young patients, other parts of the lesions showed evidence of osteoclastic remodelling of bone trabeculae, and even of the replacement of some of these structures by mature lamellar bone.

Aged↗
PubMed1997

Retinoids in neuroblastoma therapy: distinct biological properties of 9-cis- and all-trans-retinoic acid.

We investigated the potential for 9-cis-retinoic acid in the differentiation therapy of neuroblastoma using an N-type neuroblastoma cell line, SH SY 5Y, as an experimental model. In these cells, 9-cis-retinoic acid is more effective than other isomers at inducing the expression of RAR-beta. An RAR-alpha-specific antagonist inhibited the induction of RAR-beta in response to all-trans-but not to 9-cis-retinoic acid. This indicates that the mechanism of gene induction by 9-cis-retinoic acid differs markedly from all-trans-retinoic acid. 9-cis-retinoic acid is also better than all-trans at producing sustained morphological differentiation and inhibition of proliferation of SH SY 5Y cells. Although N-type neuroblastoma cells are not thought to undergo apoptosis in response to all-trans-retinoic acid, we observed a significant degree of apoptosis in SH SY 5Y cells treated with 9-cis-retinoic acid for 5 days and then cultured in the absence of retinoid, an effect not observed in cells treated with the all-trans isomer. These results suggest that 9-cis- and all-trans-retinoic acid have distinct biological properties and that 9-cis retinoic acid may be clinically effective in neuroblastoma by inducing both differentiation and apoptosis under an appropriate treatment regimen.

Alitretinoin↗
PubMed1997

9-cis retinoic acid--a better retinoid for the modulation of differentiation, proliferation and gene expression in human neuroblastoma.

To date, the clinical success of 13-cis or all-trans retinoic acid in the treatment of neuroblastoma has been disappointing. In vivo, 13-cis will isomerise to both all-trans and 9-cis retinoic acid, believed to be the main biologically-active isomers. In vitro studies with an N-type neuroblastoma cell line, SH SY 5Y, show that 9-cis is better than other isomers at both inducing morphological differentiation and inhibiting proliferation. RAR-beta, a gene which may mediate retinoic acid responsiveness and be of prognostic significance, is also more-effectively induced by 9-cis retinoic acid. 9-cis and all-trans retinoic acid do not have synergistic effects on SH SY 5Y cell proliferation and gene expression. A retinoid X receptor (RXR)-specific analogue of 9-cis retinoic acid had similar effects on gene expression to 9-cis retinoic acid alone. In view of these results, 9-cis retinoic acid or stable analogues of this retinoid may have potential for the treatment of neuroblastoma.

Alitretinoin↗
PubMed1996

Investigation of co-amplification of the candidate genes ornithine decarboxylase, ribonucleotide reductase, syndecan-1 and a DEAD box gene, DDX1, with N-myc in neuroblastoma. United Kingdom Children's Cancer Study Group.

Although N-myc amplification is strongly associated with a poor prognosis, not all patients with neuroblastomas having N-myc amplification fare badly. To investigate whether genes other than N-myc are responsible for contributing to the prognosis, we examined seven cell lines and 87 primary tumours for co-amplification of candidate genes known to be present near the normal N-myc locus: ornithine decarboxylase (ODC), ribonucleotide reductase (RRM2), syndecan-1 and a DEAD box protein gene, DDX1. Sequence analysis of the pG21 cDNA clone previously reported to represent an expressed gene frequently co-amplified with N-myc, showed this to be from the DDX1 gene. No co-amplification with the first three genes was found in any of the cell lines or tumour samples. DDX1, however was found to be amplified along with N-myc in 4/6 (67%) cell lines and 6/16 (38%) of the N-myc amplified tumours. Co-amplification of DDX1 and N-myc was found more frequently in stage 4 or 4S tumours than lower stage (1-3) tumours. With the exclusion of a single 4S case, there was a highly significant reduction in the mean disease-free interval from 24.4 +/- 4.7 (SE, n = 10) months for cases with co-amplification of N-myc and DDX1 compared with 9.2 +/- 1.8 (SE, n = 5) months for those cases showing amplification of N-myc alone (P = 0.0056, Welch's unpaired t-test). No amplification of DDX1, ODC, RRM2, or syndecan-1 was found in the absence of N-myc amplification. These observation indicate that the N-myc amplicon is of varied size and/or position relative to the N-myc gene, with DDX1 representing at least one other gene frequently co-amplified with N-myc. Further studies are required to confirm the biological and prognostic significance of DDX1 co-amplification and to elucidate the role that DDX1 plays in tumour genesis and progression.

Base Sequence↗
PubMed1996

Osteogenic sarcoma in the Rothmund-Thomson syndrome.

Two children who had the Rothmund-Thomson syndrome and developed osteosarcoma are reported. The 10 previously reported cases are reviewed. The osteosarcomas developed at a younger age than normally expected and 66% occurred in the tibia/fibula. Four of the five patients for whom information was available showed undue sensitivity to cancer chemotherapy agents with prolonged myelosuppression and severe mucositis. It is recommended that doxorubicin in particular should be given with extreme caution in such patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Micrographic surgery for subungual squamous cell carcinoma.

Eight patients were treated for subungual squamous cell carcinoma (4 female, 4 male; mean age 61 years). History of disease ranged from 9 months to 14 years (mean 4.7 years). Outpatient surgery under local anaesthetic was performed using Mohs micrographic surgery and formalin-fixed histological specimens. Tumour clearance was achieved after 2-6 procedures (median 3) over a mean period of 6.9 days. In all cases the wounds were allowed to heal by secondary intention and the distal phalanx was preserved. During a mean follow-up period of 3.1 years (range 0.5-6), no recurrence was seen and involved digits remained functional. Mohs micrographic surgery can provide a valuable alternative to amputation for subungual squamous cell carcinoma.

Aged↗
PubMed1995

Solid alveolar rhabdomyosarcoma with a t(2;13).

We report a child with a progressive "solid alveolar rhabdomyosarcoma" in whom analysis of tumor cells revealed a t(2;13) translocation characteristic of the classical alveolar subtype. Both subtypes of alveolar rhabdomyosarcoma are associated with a poor response to treatment and the occurrence of this translocation in both is suggestive of a common biologic origin.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Gene expression and neuroblastoma cell differentiation in response to retinoic acid: differential effects of 9-cis and all-trans retinoic acid.

Retinoic acid has considerable potential for the chemoprevention and chemotherapy of cancer. Neuroblastoma cells differentiate in response to retinoic acid in vitro, an observation that has led to clinical trials using either the 13-cis or all-trans isomers of retinoic acid. We review the effects of retinoic acid on neuroblastoma, and the potential involvement of nuclear retinoic acid receptors (RARs) and retinoid X receptors (RXRs). 9-cis retinoic acid is a ligand for RXRs, and we review recent data on the differential effects of 9-cis and all-trans retinoic acid on neuroblastoma differentiation and proliferation in vitro, and possible mechanisms of action via hetero- and homodimers of RARs and RXRs. Although there is uncertainty whether or not 9-cis retinoic acid produces its biological effects primarily via RXR homodimers, in vitro data suggest that this isomer of retinoic acid or stable analogues may have considerable potential for the treatment of resistant, disseminated neuroblastoma.

Antineoplastic Agents↗
PubMed1995

Synovial chondromatosis presenting as painless soft tissue mass--a report of 19 cases.

Primary synovial chondromatosis is a disorder of joints, tendon sheaths and bursae characterized by the formation and growth of cartilaginous nodules. It usually presents clinically with joint symptoms and is frequently associated with intra-articular loose bodies. A large soft tissue mass is an unusual presentation which, both clinically and radiologically, raises the suspicion of malignancy. Nineteen cases of synovial chondromatosis presenting as soft tissue tumours were reviewed. They were all adjacent to joints but with no joint symptoms. Histology showed the typical features of benign synovial chondromatosis, including foci of cartilage cells showing cytological atypia. This is well recognized and does not indicate malignancy. Clinical follow up confirmed this with local recurrence only in three patients. It is important to be aware of this unusual presentation as the alternative diagnosis of a chondrosarcoma, as initially diagnosed in some of these cases, has major implications regarding the treatment of these patients.

Adult↗
PubMed1995

Human herpes virus-6 infection in marrow graft recipients: role in pathogenesis of graft-versus-host disease. Newcastle upon Tyne Bone Marrow Transport Group.

To investigate the hypothesis that target organ infection with human herpes virus-6 (HHV-6) exacerbates the clinical severity of GVHD, skin and rectal biopsies from 34 allogeneic bone marrow transplant (BMT) recipients and 23 comparative autologous recipients were studied. Biopsies and heparinised blood samples were obtained from all patients prior to and at regular intervals after BMT, and whenever GVHD was suspected. HHV-6 antigen was detected in cryostat sections by immunohistochemistry, and HHV-6 DNA in peripheral blood leucocytes (PBL) and biopsies by nested PCR. Twenty-eight (90%) of the 31 patients who engrafted developed clinical GVHD, which was mild in five, moderately severe in nine and severe in 14. Overall, HHV-6 DNA was detected in PBl in 74% of autologous recipients and 76% of allogeneic recipients, and in biopsy tissue in 48% of autos and 71% of allos. However, HHV-6 DNA was detected in skin and/or rectal biopsies more frequently in allogeneic recipients with severe GVHD (92%) than in those with either moderate (55%) or mild GVHD (22%), suggesting an association (P = 0.004) between HHV-6 DNA in biopsy tissue and GVHD severity. A significant linear trend (P = 0.03) was identified between detection of HHV-6 DNA in biopsy tissue obtained prior to or concomitant with the onset of GVHD and increased GVHD severity, suggesting that HHV-6 was causally linked to GVHD rather than reactivated as a consequence of GVHD therapy. Thus this study supports a role for HHV-6 in the initiation and/or exacerbation of GVHD, and suggests that the presence of HHV-6 DNA in the skin or rectum may be a factor in determining GVHD severity. If confirmed, these findings may have implications for the management of allogeneic BMT recipients.

Adolescent↗
PubMed1994

Concentration-dependent effects of 9-cis retinoic acid on neuroblastoma differentiation and proliferation in vitro.

The observation that neuroblastoma cells differentiate in response to retinoic acid (RA) in vitro has led to clinical trials using either 13-cis or all-trans RA. Since 9-cis RA may also have important biological functions, we have compared the potential of RA isomers to induce differentiation and inhibit cell proliferation of SH SY 5Y neuroblastoma cells. 9-cis RA at high concentrations is better at inducing morphological differentiation than either all-trans or 13-cis RA and as effective at inhibiting proliferation. Hence, 9-cis RA or stable analogues may have important therapeutic potential in the treatment of neuroblastoma.

Cell Differentiation↗
PubMed1994

Differential effects of 9-cis and all-trans retinoic acid on the induction of retinoic acid receptor-beta and cellular retinoic acid-binding protein II in human neuroblastoma cells.

The objective of this study was to compare the properties of 9-cis and all-trans retinoic acid with respect to the induction of expression of retinoic acid receptor beta (RAR-beta) and cellular retinoic acid-binding protein (CRABP) II in human neuroblastoma SH SY 5Y cells. RAR-beta and CRABP II mRNA was induced by both all-trans and 9-cis retinoic acid in SH SY 5Y cells. Induction was rapid, detectable within 2-4 h, and inhibited by actinomycin D. Time-courses of induction for RAR-beta and CRABP II differed: RAR-beta mRNA levels reached a maximum 4-6 h after adding all-trans or 9-cis retinoic acid, whereas CRABP II mRNA levels increased over at least 18 h. These differences were attributed to the longer half-life of CRABP II mRNA (20 h) compared with RAR-beta mRNA (3.9 h). The dose-response characteristics of all-trans and 9-cis retinoic acid were different: all-trans was effective at nanomolar concentrations, whereas 10-fold higher levels of 9-cis retinoic acid were required to achieve comparable induction of RAR-beta and CRABP II. Conversely, at high concentrations, 9-cis retinoic acid gave a greater induction of RAR-beta and CRABP II than all-trans. The induction of RAR-beta and CRABP II by all-trans retinoic acid was maintained in the subsequent absence of all-trans retinoic acid, whereas induction by 9-cis retinoic acid was dependent on its continued presence in the culture medium. These results suggest that, at high concentrations, 9-cis retinoic acid may produce its transcriptional effects via retinoid X receptor (RXR) homodimers. This has implications for the cellular functions of 9-cis retinoic acid and its use as a biological response modifier.

Dactinomycin↗