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1.
Rev. esp. cir. ortop. traumatol. (Ed. impr.) ; 67(2): 144-152, Mar-Abr. 2023. ilus, tab, graf
Article in English | IBECS | ID: ibc-217116

ABSTRACT

Background: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. Methods: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). Results: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations...(AU)


Introducción: Las fracturas de calcáneo suelen ser lesiones intraarticulares de alta energía asociadas con hundimiento articular. Además, se añade con frecuencia el estallido de la pared lateral, la superposición de la pared medial, la conminución y la pérdida de hueso bajo la carilla articular. La deformidad secundaria, como el varo del retropié, altera la biomecánica del pie. Nuestra comunidad utiliza cada vez más abordajes mínimamente invasivos con reducción indirecta de la tuberosidad del calcáneo para mantener la reducción mediante tornillos posteriores. Hay estudios que proponen diferentes configuraciones de tornillos, tras experimentación biomecánica, pero aún no es bien conocido qué configuración controla mejor la deformidad en varo. Este estudio tiene como objetivo determinar la configuración óptima del tornillo para controlar la deformidad en varo en las fracturas de calcáneo Sanders 2B. Método: Se prepararon modelos en Sawbone para replicar la fractura de Sanders tipo 2B, con pérdida de hueso central y con conminución. Se eliminó una cuña medial de 0,5cm de la tuberosidad calcánea para crear inestabilidad en varo. Tras estabilizar el ángulo de Gissane con un tornillo aislado parcialmente roscado de 4mm y una placa moldeada, se utilizaron tornillos de compresión multiuso Charlotte (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) sin cabeza, canulados y parcialmente roscados de 7mm insertados sobre una AK bajo escopia. El desplazamiento del plano sagital del fragmento de tuberosidad fracturado en comparación con el cuerpo al aplicar una fuerza de 5N, 10N y 20N se midió en milímetros (mm). Resultados: Dos tornillos insertados (un tornillo medial en el sustenaculum tali de inferior a superior y un tornillo lateral en el eje largo del astrágalo) proporciona el menor desplazamiento (0,88±0,390 a 5N y 1,7±1,251 a 20N) y resulta la construcción más estable (p<0,05) en comparación con otras configuraciones...(AU)


Subject(s)
Humans , Bone Screws , Calcaneus/injuries , Heel/surgery , Biomechanical Phenomena , Orthopedics
2.
Rev. esp. cir. ortop. traumatol. (Ed. impr.) ; 67(2): T144-T15, Mar-Abr. 2023. ilus, tab, graf
Article in Spanish | IBECS | ID: ibc-217117

ABSTRACT

Background: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. Methods: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). Results: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations...(AU)


Introducción: Las fracturas de calcáneo suelen ser lesiones intraarticulares de alta energía asociadas con hundimiento articular. Además, se añade con frecuencia el estallido de la pared lateral, la superposición de la pared medial, la conminución y la pérdida de hueso bajo la carilla articular. La deformidad secundaria, como el varo del retropié, altera la biomecánica del pie. Nuestra comunidad utiliza cada vez más abordajes mínimamente invasivos con reducción indirecta de la tuberosidad del calcáneo para mantener la reducción mediante tornillos posteriores. Hay estudios que proponen diferentes configuraciones de tornillos, tras experimentación biomecánica, pero aún no es bien conocido qué configuración controla mejor la deformidad en varo. Este estudio tiene como objetivo determinar la configuración óptima del tornillo para controlar la deformidad en varo en las fracturas de calcáneo Sanders 2B. Método: Se prepararon modelos en Sawbone para replicar la fractura de Sanders tipo 2B, con pérdida de hueso central y con conminución. Se eliminó una cuña medial de 0,5cm de la tuberosidad calcánea para crear inestabilidad en varo. Tras estabilizar el ángulo de Gissane con un tornillo aislado parcialmente roscado de 4mm y una placa moldeada, se utilizaron tornillos de compresión multiuso Charlotte (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) sin cabeza, canulados y parcialmente roscados de 7mm insertados sobre una AK bajo escopia. El desplazamiento del plano sagital del fragmento de tuberosidad fracturado en comparación con el cuerpo al aplicar una fuerza de 5N, 10N y 20N se midió en milímetros (mm). Resultados: Dos tornillos insertados (un tornillo medial en el sustenaculum tali de inferior a superior y un tornillo lateral en el eje largo del astrágalo) proporciona el menor desplazamiento (0,88±0,390 a 5N y 1,7±1,251 a 20N) y resulta la construcción más estable (p<0,05) en comparación con otras configuraciones...(AU)


Subject(s)
Humans , Bone Screws , Calcaneus/injuries , Heel/surgery , Biomechanical Phenomena , Orthopedics
3.
Rev Esp Cir Ortop Traumatol ; 67(2): 144-152, 2023.
Article in English, Spanish | MEDLINE | ID: mdl-35809779

ABSTRACT

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04±0.971 at 5N and 11.24±7.590 at 20N) (p<0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.


Subject(s)
Ankle Injuries , Foot Injuries , Fractures, Bone , Fractures, Comminuted , Hallux Varus , Knee Injuries , Humans , Fracture Fixation, Internal/methods , Reproducibility of Results , Foot , Bone Screws
4.
Rev Esp Cir Ortop Traumatol ; 67(2): T144-T152, 2023.
Article in English, Spanish | MEDLINE | ID: mdl-36528297

ABSTRACT

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5 cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4 mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7 mm cannulated partially threaded CharlotteTM (Wright Medical Technology, Memphis, USA) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5 N, 10 N and 20 N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88 ± 0.390 at 5 N and 1.7 ± 1.251 at 20 N) and the most stable construct (p < 0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04 ± 0.971 at 5 N and 11.24 ± 7.590 at 20 N) (p < 0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.


Subject(s)
Ankle Injuries , Foot Injuries , Fractures, Bone , Fractures, Comminuted , Knee Injuries , Humans , Fracture Fixation, Internal/methods , Reproducibility of Results , Foot , Bone Screws
5.
J Orthop ; 17: 203-207, 2020.
Article in English | MEDLINE | ID: mdl-31889742

ABSTRACT

Lateral epicondylitis, or tennis elbow is a common condition that presents with pain and tenderness around the common extensor origin of the elbow. Tennis elbow is estimated to affect 1-3% of the adult population each year and is more common in the dominant arm. It is generally regarded as an overuse injury involving repeated wrist extension against resistance, although it can occur as an acute injury (trauma to the lateral elbow). Up to 50% of all tennis players develop symptoms due to various factors including poor swing technique the use of heavy racquet. It's also seen in labourers who utilise heavy tools or engage in repetitive gripping or lifting task. In this article, we discuss the existing literature in the field and the current thinking on optimum treatment modalities. We have reviewed the literature available on med line and have discussed the condition with our specialist colleagues in the field.

6.
Ann R Coll Surg Engl ; 99(1): 12-16, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27513791

ABSTRACT

Adult respiratory distress syndrome (ARDS) has now been described as a sequela to such diverse conditions as burns, amniotic fluid embolism, acute pancreatitis, trauma, sepsis and damage as a result of elective surgery in general. Patients with ARDS require immediate intubation, with the average patient now being ventilated for between 8 and 11 days. While the acute management of ARDS is conducted by the critical care team, almost any surgical patient can be affected by the condition and we believe that it is important that a broader spectrum of hospital doctors gain an understanding of the nature of the pathology and its current treatment.


Subject(s)
Respiratory Distress Syndrome/therapy , Adrenal Cortex Hormones/therapeutic use , Extracorporeal Membrane Oxygenation/methods , Fluid Therapy/methods , Humans , Intubation, Intratracheal/methods , Nitric Oxide/therapeutic use , Patient Positioning/methods , Positive-Pressure Respiration/methods , Pulmonary Surfactants/therapeutic use , Respiratory Distress Syndrome/diagnosis , Respiratory Distress Syndrome/etiology
7.
Ann R Coll Surg Engl ; 94(8): 539-42, 2012 Nov.
Article in English | MEDLINE | ID: mdl-23131221

ABSTRACT

INTRODUCTION: In this article we look at the aetiology of plantar fasciitis, the other common differentials for heel pain and the evidence available to support each of the major management options. We also review the literature and discuss the condition. METHODS: A literature search was performed using PubMed and MEDLINE(®). The following keywords were used, singly or in combination: 'plantar fasciitis', 'plantar heel pain', 'heel spur'. To maximise the search, backward chaining of reference lists from retrieved papers was also undertaken. FINDINGS: Plantar fasciitis is a common and often disabling condition. Because the natural history of plantar fasciitis is not understood, it is difficult to distinguish between those patients who recover spontaneously and those who respond to formal treatment. Surgical release of the plantar fascia is effective in the small proportion of patients who do not respond to conservative measures. New techniques such as endoscopic plantar release and extracorporeal shockwave therapy may have a role but the limited availability of equipment and skills means that most patients will continue to be treated by more traditional techniques.


Subject(s)
Fasciitis, Plantar/therapy , Analgesics/administration & dosage , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Blood Proteins/administration & dosage , Botulinum Toxins/therapeutic use , Diagnosis, Differential , Fasciitis, Plantar/diagnosis , Fasciitis, Plantar/etiology , Foot Orthoses , Humans , Injections, Intralesional , Life Style , Lithotripsy/methods , Muscle Stretching Exercises/methods , Patient Education as Topic , Steroids/administration & dosage
8.
Biochem Pharmacol ; 83(9): 1241-50, 2012 May 01.
Article in English | MEDLINE | ID: mdl-22326903

ABSTRACT

Anthracycline chemotherapeutics are well characterised as poisons of topoisomerase II, however many anthracyclines, including doxorubicin, are also capable of forming drug-DNA adducts. Anthracycline-DNA adducts present an unusual obstacle for cells as they are covalently attached to one DNA strand and stabilised by hydrogen bonding to the other strand. We now show that in cycling cells processing of anthracycline adducts through DNA replication appears dominant compared to processing via transcription-coupled pathways, and that the processing of these adducts into DNA breaks is independent of topoisomerase II. It has previously been shown that cells deficient in homologous recombination (HR) are hypersensitive to adduct forming treatments. Given that anthracycline-DNA adducts, whilst not true crosslinks, are associated with both DNA strands, the role of ICL repair pathways was investigated. Mus81 is a structure specific nuclease implicated in Holliday junction resolution and the resolution of branched DNA formed by stalled replication forks. We now show that ICL repair deficient cells (Mus81(-/-)) are hypersensitive to anthracycline-DNA adducts and ET-743, a compound which causes a chemically similar type of DNA damage. Further analysis of this mechanism showed that Mus81 does not appear to cause DNA breaks resulting from either anthracycline- or ET743-DNA adducts. This suggests Mus81 processes these novel forms of DNA damage in a fundamentally different way compared to the processing of classical covalent crosslinks. Improved understanding of the role of DNA repair in response to such adducts may lead to more effective chemotherapy for patients with BRCA1/2 mutations and other HR deficiencies.


Subject(s)
Anthracyclines/metabolism , Anthracyclines/pharmacology , DNA Adducts/metabolism , DNA Repair , DNA Replication , DNA-Binding Proteins/metabolism , Endonucleases/metabolism , Animals , Anthracyclines/chemistry , Cricetinae , Cricetulus , DNA Adducts/chemistry , DNA Breaks, Double-Stranded/drug effects , DNA Topoisomerases, Type II/metabolism , DNA-Binding Proteins/genetics , Dioxoles/pharmacology , Endonucleases/genetics , Fanconi Anemia Complementation Group D2 Protein/genetics , Fanconi Anemia Complementation Group D2 Protein/metabolism , G1 Phase/genetics , HL-60 Cells , Homologous Recombination , Humans , Tetrahydroisoquinolines/pharmacology , Trabectedin
9.
Eur J Trauma Emerg Surg ; 38(6): 673-7, 2012 Dec.
Article in English | MEDLINE | ID: mdl-26814555

ABSTRACT

INTRODUCTION: Fascia iliaca compartment block, performed in the emergency department (A&E) in patients presenting with femoral neck fracture, has gained increasing recognition as an adjunctive analgesic. The purpose of this study was to investigate whether fascia iliaca block (FIB) significantly reduced the requirement for systemic opiates in the pre-operative setting. MATERIALS AND METHODS: Analgesia requirements for all patients admitted with fractured neck of femur to one unit over a 9-month period were gathered prospectively. Fifty percent of patients had received FIB at diagnosis in the A&E, dependant on the expertise of the attending physician. Morphine administration between groups was analysed. RESULTS: Over a 9-month period, 286 patients with complete documentation were admitted with fractured neck of femur. At the start of the study, an informal education programme in A&E was introduced, increasing the incidence of FIB provision at diagnosis (p = <0.0001, Fisher's exact test) and reducing the average amount of morphine administered (p = 0.027, linear regression analysis). The administration of FIB reduced the average morphine requirement for a patient in A&E by 41 % when compared with those who received systemic analgesia alone (p = 0.018, Mann-Whitney test). No adverse effects were reported with FIB. CONCLUSION: Fascia iliaca compartment block is a safe and effective method of providing analgesia to patients with fractured neck of femur and reduces morphine requirement.

10.
Eur J Trauma Emerg Surg ; 37(6): 661-4, 2011 Dec.
Article in English | MEDLINE | ID: mdl-26815479

ABSTRACT

We describe a novel, simple and cost-effective method of passing sutures through the patella, without the need for expensive or specialised equipment.

11.
Anticancer Agents Med Chem ; 10(1): 70-7, 2010 Jan.
Article in English | MEDLINE | ID: mdl-19807684

ABSTRACT

Barminomycin is a member of the anthracycline class of anticancer agents and was originally discovered as a pink/red complex with DNA and RNA and named SN-07. The chromophore was subsequently separated from the nucleic acids by nuclease digestion and contained the four-membered anthraquinone ring system characteristic of anthracyclines, but with an unusual eight membered ring that contained a carbinolamine which readily interconverted to an imine. The imine form is analogous to the formaldehyde-activated form of other anthracyclines such as doxorubicin. The imine form confers exceptional activity to barminomycin which is 1,000-fold more cytotoxic than doxorubicin. Barminomycin rapidly forms adducts with DNA, reacting with the exocyclic amino group of guanine residues and with high selectivity for 5'-GC-3' sequences. The coupling to DNA appears to be identical to the N-C-N aminal linkage formed between doxorubicin and DNA where the carbon derives from formaldehyde for doxorubicin-DNA adducts, whereas this "activated carbon" is an inherent component of the imine group in the eight membered ring of barminomycin. Although the linkage of both drugs to DNA appears to be identical, barminomycin-DNA complexes are essentially irreversible compared to the labile doxorubicin-DNA adducts which have an in vitro (purified DNA) half-life of 25 h at 37 degrees C. A 3D model of the barminomycin-DNA complex has been defined from 307 NOE distance constraints. The enhanced stability of barminomycin-DNA adducts appears to be due primarily to protection of the aminal linkage from hydrolysis and this has provided insight into the design of new anthracycline derivatives with enhanced stability and activity. Strategies for harnessing the extreme reactivity and activity of barminomycin are also presented.


Subject(s)
Anthracyclines/chemistry , Anthracyclines/pharmacology , DNA Adducts/chemistry , Drug Discovery , Magnetic Resonance Spectroscopy , Models, Molecular
12.
Br J Cancer ; 96(11): 1667-74, 2007 Jun 04.
Article in English | MEDLINE | ID: mdl-17473824

ABSTRACT

Formaldehyde has been previously shown to play a dominant role in promoting synergy between doxorubicin (Dox) and formaldehyde-releasing butyric acid (BA) prodrugs in killing cancer cells. In this work, we report that these prodrugs also protect neonatal rat cardiomyocytes and adult mice against toxicity elicited by Dox. In cardiomyocytes treated with Dox, the formaldehyde releasing prodrugs butyroyloxymethyl diethylphosphate (AN-7) and butyroyloxymethyl butyrate (AN-1), but not the corresponding acetaldehyde-releasing butyroyloxydiethyl phosphate (AN-88) or butyroyloxyethyl butyrate (AN-11), reduced lactate dehydrogenase leakage, prevented loss of mitochondrial membrane potential (DeltaPsim) and attenuated upregulation of the proapoptotic gene Bax. In Dox-treated mice, AN-7 but not AN-88 attenuated weight-loss and mortality, and increase in serum lactate dehydrogenase. These findings show that BA prodrugs that release formaldehyde and augment Dox anticancer activity also protect against Dox cardiotoxicity. Based on these observations, clinical applications of these prodrugs for patients treated with Dox warrant further investigation.


Subject(s)
Antineoplastic Agents/toxicity , Butyric Acid/pharmacology , Cytoprotection/drug effects , Doxorubicin/toxicity , Formaldehyde/pharmacology , Myocytes, Cardiac/drug effects , Organophosphates/pharmacology , Prodrugs/pharmacology , Animals , Animals, Newborn , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Butyrates , Butyric Acid/metabolism , Cells, Cultured , Drug Evaluation, Preclinical , Female , Formaldehyde/metabolism , Gene Expression Regulation/drug effects , Histone Deacetylases/metabolism , Membrane Potential, Mitochondrial/drug effects , Mice , Mice, Inbred C57BL , Models, Biological , Myocytes, Cardiac/metabolism , Organophosphorus Compounds , Rats
13.
Curr Med Chem Anticancer Agents ; 5(5): 431-47, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16178771

ABSTRACT

The anthracycline group of compounds are amongst the most effective chemotherapy agents currently in use for cancer treatment. They are generally classified as topoisomerase II inhibitors but also have a variety of other targets in cells. It has been known for some years that the anthracyclines are capable of forming DNA adducts, but the relevance and extent of these DNA adducts in cells and their role in causing cell death has remained obscure. When the adduct structure was solved, it became clear that formaldehyde was an absolute requirement for adduct formation. This led to a renewed interest in the capacity of anthracyclines to form DNA adducts, and there are now several ways in which adduct formation can be facilitated in cells. These involve strategies to provide the requisite formaldehyde in the form of anthracycline-formaldehyde conjugates, and the use of formaldehyde-releasing drugs in combination with anthracyclines. Of particular interest is the new therapeutic compound AN-9 that releases both butyric acid and formaldehyde, leading to efficient anthracycline-DNA adduct formation, and synergy between the two compounds. Targeted formation of adducts using anthracycline-formaldehyde conjugates tethered to cell surface targeted molecules is now also possible. Some of the cellular consequences of these adducts have now been studied, and it appears that their formation can overcome anthracycline-resistance mechanisms, and that they are more efficient at inducing apoptosis than when functioning primarily through impairment of topoisomerase II. The clinical application of the use of anthracyclines as DNA adduct forming agents is now being explored.


Subject(s)
Anthracyclines/pharmacology , Formaldehyde/chemistry , Animals , Anthracyclines/chemistry , Anthracyclines/metabolism , Apoptosis/drug effects , DNA Adducts/drug effects , DNA Adducts/metabolism , Formaldehyde/metabolism , Formaldehyde/pharmacology , Humans , Molecular Structure , Structure-Activity Relationship
14.
Hip Int ; 15(3): 155-158, 2005.
Article in English | MEDLINE | ID: mdl-28224600

ABSTRACT

Between 1996 and 2002, we treated 60 patients (65 hips) by hip resurfacing. The notes and radiographs of these cases were studied retrospectively and the modalities of failure identified. At a mean follow-up of 51 months, 14 of these cases (22%) required revision surgery. One patient had died from unrelated causes and one was lost to follow-up. At the time of primary surgery, the mean age of the patients in our series was 55 years. The commonest mechanism of failure in our series was fractured neck of femur (six cases). Four of these occurred in females over the age of 60. None of the fractured necks of femur were associated with trauma. There were four cases of loose acetabular components and one case of progressive AVN (avascular necrosis). Two patients required revision surgery for ongoing hip pain and one required a twostage revision for early deep infection. (Hip International 2005; 15: 155-8).

15.
Cancer Res ; 61(22): 8194-202, 2001 Nov 15.
Article in English | MEDLINE | ID: mdl-11719450

ABSTRACT

The interaction of Adriamycin and pivaloyloxymethyl butyrate (AN-9) was investigated in IMR-32 neuroblastoma and MCF-7 breast adenocarcinoma cells. Adriamycin is a widely used anticancer drug, whereas AN-9 is an anticancer agent presently undergoing Phase II clinical trials. The anticancer activity of AN-9 has been attributed to its ability to act as a butyric acid prodrug, although it also releases formaldehyde and pivalic acid. Adriamycin and AN-9 in combination display synergy when exposed simultaneously to cells or when AN-9 treatment is up to 18 h after Adriamycin administration. However, the reverse order of addition results in antagonism. These interactions have been established using cell viability assays and classical isobologram analysis. To understand the molecular basis of this synergy, the relative levels of Adriamycin-DNA adducts were determined using various treatment combinations. Levels of Adriamycin-DNA adducts were enhanced when treatment combinations known to be synergistic were used and were diminished using those treatments known to be antagonistic. The relative timing of the addition of Adriamycin and AN-9 was critical, with a 20-fold enhancement of Adriamycin-DNA adducts occurring when AN-9 was administered 2 h after the exposure of cells to Adriamycin. The enhanced levels of these adducts and the accompanying decreased cell viability were directly related to the esterase-dependent release of formaldehyde from AN-9, providing evidence for the formaldehyde-mediated activation of Adriamycin.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Butyrates/pharmacokinetics , Doxorubicin/pharmacology , Formaldehyde/pharmacology , Prodrugs/pharmacokinetics , Adenocarcinoma/drug therapy , Adenocarcinoma/metabolism , Biotransformation , Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Butyrates/administration & dosage , Butyrates/pharmacology , DNA Adducts/biosynthesis , Doxorubicin/administration & dosage , Doxorubicin/pharmacokinetics , Drug Administration Schedule , Drug Synergism , Formaldehyde/pharmacokinetics , Humans , Neuroblastoma/drug therapy , Neuroblastoma/metabolism , Prodrugs/administration & dosage , Prodrugs/pharmacology , Tumor Cells, Cultured
16.
Chem Biol Interact ; 138(2): 137-53, 2001 Nov 28.
Article in English | MEDLINE | ID: mdl-11672697

ABSTRACT

The anthracycline Adriamycin is known to form adducts with DNA, but requires prior activation by formaldehyde. In contrast, the anthracycline barminomycin is also able to form adducts with DNA, but does not require activation by formaldehyde. Barminomycin, therefore, appears to function as a pre-activated form of Adriamycin. The DNA adducts formed by both anthracyclines are bound covalently to only one strand of DNA, but both also stabilise duplex DNA sufficiently that they can be detected as virtual interstrand crosslinks in heat denaturation electrophoretic crosslinking assays. The barminomycin-DNA adducts form extremely rapidly with DNA, and at exceedingly low concentrations (approximately 50-fold lower than with Adriamycin in the presence of excess formaldehyde), both characteristics consistent with barminomycin being in a pre-activated state, hence, undergoing a bimolecular reaction with DNA compared with the trimolecular reaction (drug, formaldehyde and DNA) required with Adriamycin. Surprisingly, barminomycin-DNA adducts are substantially more stable (essentially irreversible) than Adriamycin-DNA adducts (half life of approximately 25 h at 37 degrees C). Due to this understanding of the reactivity of barminomycin and its exceptional cytotoxicity (1000-fold more cytotoxic than Adriamycin), detailed structural studies of barminomycin-DNA adducts are now warranted, both in vitro and in tumour cells.


Subject(s)
Anthracyclines/chemistry , Antibiotics, Antineoplastic/chemistry , Antineoplastic Agents , Doxorubicin , Animals , Anthracyclines/pharmacology , Antibiotics, Antineoplastic/pharmacology , Cattle , Cross-Linking Reagents/chemistry , Cross-Linking Reagents/metabolism , DNA/chemistry , DNA/drug effects , DNA/metabolism , DNA Adducts/chemistry , DNA Adducts/metabolism , Dose-Response Relationship, Drug , Formaldehyde/chemistry , Formaldehyde/metabolism , Hot Temperature , In Vitro Techniques , Kinetics , Spectrometry, Mass, Electrospray Ionization
18.
J Inorg Biochem ; 84(1-2): 119-27, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11330470

ABSTRACT

The non-covalent binding of [(en)Pt(mu-dpzm)2Pt(en)]4+ to segments of DNA containing only G and C bases has been studied to gain an understanding of the pre-covalent binding association of cationic polynuclear platinum(II) anti-cancer drugs at G/C sites. 1H-NMR and CD spectroscopy were used to study the binding of the metal complex to the oligonucleotide d(GC)5 and the polynucleotide poly(dG-dC).poly(dG-dC), respectively. NOE contacts between the metal complex protons and the oligonucleotide sugar H1' protons observed in NOESY spectra indicated that the metal complex bound in the minor groove at the central C4 to G7 region of the oligonucleotide. This result indicates that even though cationic polynuclear platinum(II) complexes bind covalently in the major groove at G/C sites, the pre-covalent binding association is favoured in the minor groove. CD spectra indicated that the addition of the metal complex to poly(dG-dC)-poly(dG-dC) induced some conformational changes, but it was not possible to conclude that [(en)Pt(mu-dpzm)2Pt(en)]4+ induced a B- to Z-type DNA transition. In addition, in vitro transcription assays using the lac UV5 promoter showed that the non-covalent binding of [(en)Pt(mu-dpzm)2Pt(en)]4+ was sufficiently stable to inhibit transcription, and at particular sites.


Subject(s)
DNA/metabolism , Organoplatinum Compounds/metabolism , Pyrazoles/metabolism , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Base Composition , Base Sequence , Binding Sites , Circular Dichroism , DNA/chemistry , DNA/drug effects , In Vitro Techniques , Magnetic Resonance Spectroscopy , Molecular Sequence Data , Nucleic Acid Conformation/drug effects , Oligodeoxyribonucleotides/chemistry , Oligodeoxyribonucleotides/metabolism , Organoplatinum Compounds/chemistry , Organoplatinum Compounds/pharmacology , Polydeoxyribonucleotides/chemistry , Polydeoxyribonucleotides/metabolism , Pyrazoles/chemistry , Pyrazoles/pharmacology
19.
Proc Natl Acad Sci U S A ; 98(10): 5705-10, 2001 May 08.
Article in English | MEDLINE | ID: mdl-11331754

ABSTRACT

Neocentromeres (NCs) are fully functional centromeres that arise ectopically in noncentromeric regions lacking alpha-satellite DNA. Using telomere-associated chromosome truncation, we have produced a series of minichromosomes (MiCs) from a mardel(10) marker chromosome containing a previously characterized human NC. These MiCs range in size from approximately 0.7 to 1.8 Mb and contain single-copy intact genomic DNA from the 10q25 region. Two of these NC-based Mi-Cs (NC-MiCs) appear circular whereas one is linear. All demonstrate stability in both structure and mitotic transmission in the absence of drug selection. Presence of a functional NC is shown by binding a host of key centromere-associated proteins. These NC-MiCs provide direct evidence for mitotic segregation function of the NC DNA and represent examples of stable mammalian MiCs lacking centromeric repeats.


Subject(s)
Centromere , Chromosomes, Human , Telomere , Cell Line , Gene Transfer Techniques , Humans , In Situ Hybridization, Fluorescence
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