Sudden death among patients with acute promyelocytic leukemia treated with arsenic trioxide

Arsenic trioxide has been shown to be effective in treating acute promyelocytic leukemia (APL), with minimal overall toxicity reported to date. A phase I/II study was initiated in June 1998 using arsenic trioxide for relapsed APL to determine the maximum tolerated or minimal effective dose and to determine the efficacy of treatment at that dose. Ten patients received 1 to 4 monthly cycles of treatment with 0.1 mg/kg per day intravenous arsenic trioxide. Six of 7 patients evaluable for response achieved cytogenetic or molecular complete remission. However, 3 patients died suddenly during the first cycle of treatment. Autopsies obtained on 2 of these failed to identify a cause of sudden death, despite evidence of pulmonary hemorrhage in one. A third patient, for whom an autopsy was not performed, became asystolic and died while on continuous cardiac telemetry. These observations suggest that arsenic trioxide may be significantly or even fatally toxic at doses currently used and that caution is warranted in its use.

A 24-base-pair sequence 3' to the human erythropoietin gene contains a hypoxia-responsive transcriptional enhancer

Erythropoietin (Epo) synthesis increases in response to hypoxia. The hepatoma cell line Hep 3B produces low basal levels of Epo mRNA which increase markedly with hypoxia. To define the sequences necessary for this response, we linked fragments of the human Epo gene to a luciferase vector, introduced these plasmids into Hep 3B cells and assayed for luciferase activity after growth in 1% or 21% oxygen. A 621-bp Epo promoter fragment resulted in a 2.4-fold increase in luciferase activity with hypoxia. We tested several Epo gene fragments upstream of this Epo promoter fragment and found that a 613-bp Bgl II-Pvu II 3' fragment had a 10-fold increase in activity with hypoxia regardless of orientation. This fragment had a similar level of activity when linked to a simian virus 40 promoter. Portions of this fragment retained activity, including a 38-bp Apa I-Taq I fragment that had a 17-fold increase in activity with hypoxia. Deletion of nt 4-13 or 19-28 from this 38-bp fragment resulted in a loss of activity. The 24-bp upstream portion of the 38-bp fragment showed an 8-fold increase in activity with hypoxia. However, deletion of nt 19-24 or mutagenesis of nt 21 or 22 in this 24-bp fragment resulted in loss of activity. Our studies indicate that the transcriptional response of the human Epo gene to hypoxia is mediated in part by promoter sequences and to a greater degree by an enhancer element located in a 24-bp portion of the 3' flanking sequence of the gene.

Human beta-globin gene expression in transgenic mice is enhanced by a distant DNase I hypersensitive site

Several lines of evidence suggest that erythroid-specific DNase I hypersensitive sites (HS) located far upstream of the human beta-globin gene are important in regulating beta-globin gene expression. We used the polymerase chain reaction technique to amplify and clone an 882-base-pair DNA fragment spanning one of these HS, designated HSII, which is located 54 kilobases upstream of the beta-globin gene. The cloned HSII fragment was linked to a human beta-globin gene in either the genomic (HSII-beta) or antigenomic (HSII-beta) orientation. These two constructs and a beta-globin gene alone (beta) were injected into fertilized mouse eggs, and expression was analyzed in liver and brain from day-16 transgenic fetuses. Five of 7 beta-transgenic fetuses expressed human beta-globin mRNA, but the level of expression per gene copy was low, ranging from 0.93 to 22.4% of mouse alpha-globin mRNA (average 9.9%). In contrast, 11 of 12 HSII-beta transgenic fetuses expressed beta-globin mRNA at levels per gene copy ranging from 31.3 to 336.6% of mouse alpha-globin mRNA (average 139.5%). Only three fetuses containing intact copies of the HSII-beta construct were produced. Two of three expressed human beta-globin mRNA at levels per gene copy of 179.2 and 387.1%. Expression of human beta-globin mRNA was tissue-specific in all three types of transgenic fetuses. These studies demonstrate that a small DNA fragment containing a single erythroid-specific HS can stimulate high-level human beta-globin gene expression in transgenic mice.

A distant gene deletion affects beta-globin gene function in an atypical gamma delta beta-thalassemia

We describe an English family with an atypical gamma delta beta-thalassemia syndrome. Heterozygosity results in a beta-thalassemia phenotype with normal hemoglobin A2. However, unlike previously described cases, no history of neonatal hemolytic anemia requiring blood transfusion was obtained. Gene mapping showed a deletion that extended from the third exon of the G gamma-globin gene upstream for approximately 100 kilobases (kb). The A gamma-globin, psi beta-, delta-, and beta-globin genes in cis remained intact. The malfunction of the beta-globin gene on a chromosome in which the deletion is located 25 kb away suggests that chromatin structure and conformation are important for globin gene expression.

Pooled analysis of 3 randomized, controlled trials of interleukin-2 therapy in adult human immunodeficiency virus type 1 disease

We collected human immunodeficiency virus (HIV) disease progression, survival, most recent CD4 cell count, and plasma HIV RNA levels from patients (n=157) who participated in randomized clinical trials of interleukin (IL)-2 that commenced before 1995. Data were available for 155 (99%) patients. Statistical analyses were based on the intention-to-treat principle. Median follow-up was 28 months and 30 months for control and IL-2 patients, respectively. Twenty-five (16%) patients developed AIDS or died during follow-up (16 control patients vs. 9 IL-2 patients; R2=0.57; P=.22). Mean change from baseline CD4 cell count was significantly higher in patients randomized to receive IL-2 (368 vs. 153 cells/microL; P=.003). Mean change from baseline plasma HIV RNA was significantly lower in patients randomized to receive IL-2 (-0.98 vs. -0.63 log copies/mL; P=.004). Significant improvements in CD4 cell count and plasma HIV RNA in recipients of IL-2 relative to control patients were associated with a nonsignificant trend toward improved clinical outcome.

Dissection of the enhancer activity of beta-globin 5' DNase I-hypersensitive site 2 in transgenic mice

The beta-globin locus control region (LCR) consists of four erythroid-specific DNase I-hypersensitive sites, which are necessary for high-level expression of the beta-like globin genes in erythroid tissues. One of these sites, designated 5'HS-2, functions as an erythroid-specific enhancer element in transfection and transgenic mouse experiments. Recent transfection experiments and studies of DNA-protein interactions have localized the 5'HS-2 enhancer to 18 nucleotides that contain a binding site for both the erythroid-specific factor nuclear factor erythroid 2 (NFE-2) and for activator protein 1 (AP-1). To define the sequences necessary for in vivo enhancer activity, several deletion mutants of 5'HS-2 were linked to the human beta-globin gene and their activity was tested in transgenic mice. Three upstream fragments of 5'HS-2 [341, 374, and 412 base pairs (bp)], each of which contained the NFE-2/AP-1 sequences, resulted in beta-globin expression at levels equivalent to or higher than those observed with the entire 732-bp 5'HS-2 fragment. In contrast, a 358-bp downstream portion of 5'HS-2, which lacked the NFE-2/AP-1 sequences, resulted in beta-globin expression at the low levels seen with the beta-globin gene alone. Removal of the NFE-2/AP-1 sequences by a 67-bp internal deletion resulted in similar low levels of beta-globin expression. A 100-bp 5' fragment that contained the NFE-2/AP-1 sequences resulted in beta-globin expression that was higher than the beta-globin gene alone but lower than the entire 5'HS-2 fragment or the three larger upstream fragments. These studies demonstrate that the NFE-2/AP-1 sequences are essential for enhancer activity of 5'HS-2 but that other sequences are required for full activity in vivo.

Hypoxia-induced in vivo sickling of transgenic mouse red cells

To develop an animal model for sickle cell anemia, we have created transgenic mice that express a severe naturally occurring human sickling hemoglobin, Hb S Antilles. Due to its low solubility and oxygen affinity, Hb S Antilles has a greater propensity to cause red cell sickling than Hb S. To make transgenic animals that express a high level of Hb S Antilles, the erythroid-specific DNAse I hypersensitive site II from the human beta-globin cluster was linked independently to the human alpha 2-globin gene and to the beta S Antilles gene. Embryos were injected with both constructs simultaneously and seven transgenic mice were obtained, three of which contained both the human alpha and the human beta S Antilles transgene. After crossing the human transgenes into the mouse beta-thalassemic background a transgenic mouse line was derived in which approximately half the beta-globin chains in the murine red cells were human beta S Antilles. Deoxygenation of the transgenic red cells in vitro resulted in extensive sickling. An increase of in vivo sickling was achieved by placing these transgenic mice in a low oxygen environment. This murine model for red cell sickling should help to advance our understanding of sickle cell disease and may provide a model to test therapeutic interventions.

Regulation of human erythropoietin gene induction by upstream flanking sequences in transgenic mice

Human erythropoietin (Epo) gene expression is inducible by hypoxia or anaemia in the kidney and liver. Previous transgenic mouse experiments have demonstrated that sequences required for Epo gene induction in the kidney reside in a 7 8 kb Barn HI fragment located 6 kb upstream of the gene. To sublocalize these sequences, we performed Desoxyribonuclease I (DNAse I) mapping studies using transgenic mice which carried this DNA fragment. These studies revealed a DNAse I hypersensitive site (DNAse I HS) located 4 6 kb from the upstream end of the 7.8 kb fragment in anaemic kidney and liver samples. Sequence analysis of the region encompassing the DNAse I HS revealed an element with remarkable homology to the 3' Epo gene hypoxia-inducible enhancer. This suggested the presence of an additional regulatory element that contributes to the control of hypoxia-inducible Epo gene expression in kidney and liver. We constructed transgenic mice containing the human Epo gene linked to either the 5 kb upstream or 2.5 kb downstream portion of the 7.8kb fragment. Inducible expression was limited to the liver. Thus, neither fragment was alone sufficient to confer kidney inducible expression. These findings indicate that sequences more than 8.5 kb upstream of the Epo gene are required for kidney-specific induction. They suggest that either those sequences reside in an 0.3 kb Hind III fragment located between the 5 kb and the 2.5 kb fragments or that sequences in the 5 kb or 0.3 kb fragments must interact with sequences in the 2.5 kb fragment to allow Epo gene induction in the kidney.

Normal saline wound dressing--is it really normal?

Gauze swabs soaked in normal saline are frequently used as dressing on open wounds. Their exact mechanism of action is not known. This study was designed to assess the hypothesis that normal saline dressings act in part as an osmotic dressing. Ten patients had skin ulcers (n = 10) dressed with normal saline soaked sponges. Acting as controls (n = 10) identical sponges were placed upon intact skin. The sponge fluid osmolarity and electrolyte concentrations were serially assayed to test our hypothesis. In the control group, the osmolarity, sodium and chloride concentrations increased with time as a result of evaporation, altering it from an isotonic to a hypertonic dressing. However, in the ulcer group, the osmolarity, sodium and chloride concentrations in the sponge fluid remained relatively isotonic with time. This result is statistically significant (P< 0.05). We postulate that, as a result of evaporation, the sponge dressing increases its tonicity. This draws fluid from the wound into the dressing so that a dynamic equilibrium occurs and the sponge dressing regains isotonicity. The dressing remains functional provided that the wound fluid is absorbed freely from the wound. This process is terminated when either the dressing completely absorbs the wound fluid or the dressing dries out. The latter often occurs prematurely in a contaminated wound or in a wound where exudate forms a non-permeable barrier which prevents osmosis and allows the remaining water in the dressing to evaporate completely. This correlates with the observation in clinical practice that for maximum efficacy the dressing should be changed regularly.

A randomized, double-blinded, pilot trial of aprepitant added to standard antiemetics during conditioning therapy for hematopoietic stem cell transplant (HSCT)

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Background: Antiemetic prophylaxis for standard dose chemotherapy has improved while that for high dose chemotherapy ± total body irradiation (TBI) has not. Aprepitant (A), a neurokinin-1 antagonist, was added to standard antiemetic therapy for planned conventional HSCT to test for improved emesis control. Methods: During cyclophosphamide (Cy)-based conditioning therapy patients were randomized to receive ondansetron (O) ± dexamethasone plus A or a placebo (P) on days of chemo/radiotherapy. The primary aim was to reduce N/V during and after HSCT conditioning. Nausea, emesis, and nutritional intake were evaluated from the onset of therapy through day +7. Busulfan doses were targeted to disease appropriate AUCs and pharmacokinetic (PK) analysis was performed on Cy, Cy- metabolites (HCY & CEPM), and A. Responses were defined as Complete (CR) - no emesis, mild-moderate nausea, and Major (MR) - 1–2 emesis on only 1 day with any level nausea or no emesis with severe nausea. Results: Fifteen patients have been randomized per arm. Eleven patients received TBI (1,200 cGy) CY (120 mg/kg) and 19 received Bu (16 mg/kg) CY (120 mg/kg). A/P was begun on Day -7 (125 mg) with the first O dose and given daily (80 mg) through day +4 (alone on days +1 through +4). Overall responses (CR + MR) were seen in 14/15 A patients and 7/15 P patients. (p=0.014) No emesis occurred in 10/15 A patients and 5/15 P patients (p=0.143). Preliminary PK show the observed AUCs of CY, HCY and CEPM, for both regimens and PK differences between the 2 regimens, were consistent with previously published data. Most busulfan patients, 87%, required dose adjustments (primarily reductions) to stay within target AUCs. Anti-seizure prophylaxis with phenytoin may significantly decrease A levels, but this didn't appear to be clinically relevant. Adverse effects were similar between arms. One case of sinusoidal obstruction syndrome occurred in the P arm. Conclusions: In this interim analysis, aprepitant added to standard antiemetics improved emesis prevention during Cy-containing conditioning therapy prior to HSCT, without significant changes in Cy pharmacokinetics or increased toxicity. Data on the target accrual of 40 patients will be presented.

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Temperature-sensitive mutants of bacteriophage mu

Temperature-sensitive mutants of bacteriophage Mu, which grow at 32 C but not at 42 C, have been isolated. These mutants fall into two groups. Group 1 mutants fail to lyse host cells at nonpermissive temperatures, whereas lysis occurs normally with the group 2 mutants. All of the group 1 mutants apparently belong to the cistrons mapping to the left of gene C, whereas the group 2 mutants have lesions in various genes between D and S.

Thrower's fracture of the humerus with radial nerve palsy: an unfamiliar softball injury

A fracture of the normal humerus in a healthy young adult most commonly results from significant direct trauma. Throwing sports have become increasingly popular outside of North America and bring with them a novel injury mechanism for clinicians. A 21 year old woman sustained a "thrower's fracture" of the distal humerus and radial nerve palsy while throwing a softball. She was treated by internal fixation. Her fracture united, and radial nerve neurapraxia resolved after 8 weeks. Clinicians should be aware of this entity so that prodromal symptoms can be recognised early and thrower's fractures are not investigated unnecessarily.

Toxic megacolon: a life-threatening complication of high-dose therapy and autologous stem cell transplantation among patients with AL amyloidosis

AL amyloidosis is a plasma cell disorder in which tissue deposition of immunoglobulin light chains leads to organ dysfunction. Recent reports of high-dose therapy with autologous stem cell transplantation for amyloidosis suggest higher response rates and extended survival compared to those seen with conventional chemotherapy. However, substantial treatment-related toxicity has been observed. This case series describes our institutional experience with autologous transplantation in four patients with amyloidosis with an emphasis on unique gastrointestinal toxicities, including toxic megacolon.

Autocrine stimulation by erythropoietin in transgenic mice results in erythroid proliferation without neoplastic transformation

Erythropoietin (Epo) autocrine stimulation has been implicated in erythroleukemia. To develop a model of Epo autocrine stimulation, we made transgenic mice using a construct that linked the human Epo gene to an erythroid-specific regulatory element, designated 5'HS-2, from the human beta-globin locus control region. We hypothesized that Epo gene expression would be targeted to erythroid cells in these mice, resulting in autocrine stimulation of erythroid progenitor cell growth in culture, and that chronic autocrine Epo stimulation would result in erythroleukemia. Transgenic mice containing intact copies of the 5'HS-2Epo construction had elevated hematocrits, reticulocyte counts and serum Epo levels and marked splenic enlargement. Analysis of RNA isolated from organs of transgenic mice revealed constitutive Epo mRNA expression primarily in spleen, blood and bone marrow. RNA samples from anemic transgenic mice revealed Epo gene induction only in the liver. Marrow derived from 5'HS-2Epo mice grew BFU-E in the absence of exogenous Epo. Despite observation of up to 2 years, no mouse developed erythroleukemia, demonstrating that Epo autocrine stimulation alone is insufficient for progression to malignancy. These studies show that 5'HS-2 can be used to target Epo gene expression to erythroid tissue. These mice could provide a model system for studying autocrine growth regulation.

Self-reported complication rates following primary total hip arthroplasty in Ireland: fact or fiction

BACKGROUND

There are little data available on complication rates following primary total hip arthroplasty (THA) surgery in Ireland.

AIMS

To determine self-reported complication rates and national data for primary THA.

METHODS

A postal questionnaire surveyed Irish orthopaedic association consultant members. Additional data were obtained from the economic and social research institute (ESRI).

RESULTS

We achieved an 83% response rate. 5,424 THAs were self-reported. Mean dislocation rates were 1%, but higher using a posterior surgical approach (p < 0.05). Mean deep infection rates were 0.4%. 29% were MRSA. No reduction was reported from additional barrier prophylaxes. Mean venous thrombo-embolism (VTE) rates were 3.5%. No reduction was reported from commencing prophylaxis preoperatively or extending treatment duration. National rates for dislocation, deep infection and VTE were 25.7, 0.87, and <0.1%, respectively.

CONCLUSIONS

The creation of a National Hip Register is strongly recommended. A register would improve surgical practices and patient outcomes, and provide significant healthcare savings.

Assessment of the "nearly normal" cervical spine radiograph: C2-C3 pseudosubluxation in an adult with whiplash injury

C2-C3 pseudosubluxation is a well recognized normal anatomical variant in children and this physiological spondylolisthesis often makes the interpretation of paediatric cervical spine radiographs difficult. In direct contrast, this finding is rare in adults and has not been reported as a diagnostic difficulty following neck injury. We report a case of C2-C3 pseudosubluxation occurring in a 27 year old woman presenting with neck pain 1 week after a road traffic accident. Although there are effective radiological guidelines for cervical spine radiograph evaluation in children, there is no evidence that these can be applied to the adult cervical spine. Flexion and extension cervical spine views have limitations. In such cases, magnetic resonance imaging is required to definitively exclude pathological injury.

Deep vein thrombosis in trauma: a prospective study of lower limb orthopedic trauma patients in Tianjin Hospital, China

AIM

Pulmonary embolism is a third leading cause of death in trauma patients. The prevalence of deep vein thrombosis (DVT) in Asian countries is considered to be less than in Western countries. Our aim was to establish the rate of DVT in orthopedic trauma patients in Tianjin Hospital, to identify DVT risk factors and to support the use of prophylaxis.

METHODS

Patients admitted between November 2003 and October 2004 with recent fracture had data collected prospectively to record type of fracture, mechanism of injury, history of DVT, blood transfusion requirements, operation details, extent of postoperative swelling, use of traction, immobilization, bandaging and patient positioning. Each patient had 3 duplex ultrasound examinations, the first within 24 h of admission. Patients requiring surgery had a second ultrasound within 2 days preoperatively, then 7 days postoperatively. Patients not requiring surgery had second and third ultrasound examinations 5 and 14 days after admission.

RESULTS

There were 547 patients, median age 39.6 years (interquartile range: 28-50 years). DVT developed in 12.4% (95% confidence interval: 9.7-15.2%), most occurring with femoral shaft fractures (30.6%), 15.8% occurred with hip fractures, 14.5% with fractures around the knee and 10.8% with fractured tibia and fibula. Over half of DVTs (56.7%) developed within 3 days following injury.

CONCLUSION

The incidence of DVT in Chinese orthopedic trauma patients approaches that in Western countries. Guidelines for DVT prophylaxis should be applied in China as in Western countries.

Closure of anterior palate fistulae

Attempts at closure of anterior palate fistulas using local tissue have resulted in a high rate of failure. In addition most of these patients have associated maxillary collapse which must be corrected prior to surgery. A technique using a buccal mucosal flap to gain unscarred tissue for the anterior closure and bone grafts to fill the bony defect has been performed in nineteen patients with anterior palate fistulas. The results have been satisfactory from a functional and esthetic standpoint. In addition associated deformities have been corrected simultaneously.

The inactive beta globin gene on a gamma delta beta thalassemia chromosome has a normal structure and functions normally in vitro

We have previously described an English family with gamma delta beta-thalassemia in which a large deletion stops 25 kilobases (kb) upstream from the beta-globin gene locus, and yet the beta-globin gene is inactive in vivo. Affected family members had a beta-thalassemia minor phenotype with a normal hemoglobin A2 level. Gene mapping showed that these subjects were heterozygous for a chromosome bearing a large deletion that began in the G gamma-globin gene, extended through the epsilon-globin gene, and continued upstream for at least 75 kb. The A gamma-, delta-, and beta-globin gene loci on this chromosome were intact. To examine the possibility that an additional defect was present in the beta-globin gene, we cloned, sequenced, and examined the expression of the beta-globin gene from the affected chromosome. No mutation was found in the beta-globin gene sequence from 990 base-pairs 5' to the cap site to 350 basepairs 3' to the polyadenylation signal. The gene was subcloned into an expression vector and introduced into HeLa cells. Analysis of RNA derived from these cells, using a ribonuclease protection assay, revealed qualitatively and quantitatively normal transcription. Thus a structurally and functionally normal beta-globin gene is inactive in the presence of a large deletion more than 25 kb upstream. The loss of beta-globin gene function may be due to disturbance of chromatin conformation caused by the deletion or may be the result of loss of upstream sequences that are necessary for beta-globin gene expression in vivo.

'Ready-access' CT imaging for an orthopaedic trauma clinic

'Ready-Access' to CT imaging facilities in Orthopaedic Trauma Clinics is not a standard facility. This facility has been available at the regional trauma unit, in Merlin Park Hospital, Galway for the past four years. We reviewed the use of this facility over a 2-year period when 100 patients had CT scans as part of their trauma clinic assessment. The rate of CT scan per clinic was 0.6. The mean waiting time for a CT scan was 30 minutes. 20 (20%) new fractures were confirmed, 33 (33%) fractures were out-ruled, 25 (25%) fractures demonstrated additional information and 8 (8%) had additional fractures. 20 (20%) patients were discharged and 12 (12%) patients were admitted as a result of the CT scan. It adds little time and cost to CT scanning lists.