Expression of human coagulation factor VIII in adipocytes transduced with the simian immunodeficiency virus agmTYO1-based vector for hemophilia A gene therapy

We demonstrate that transduction of adipocytes with a simian immunodeficiency virus agm TYO1 (SIVagm)-based lentiviral vector carrying the human coagulation factor VIII gene (SIVhFVIII) resulted in expression of the human FVIII transgene in vitro and in db/db mice in vivo. Cultured human adipocytes were transduced with the SIVagm vector carrying the GFP gene in a dose-dependent manner and transduction of adipocytes with SIVhFVIII resulted in efficient expression of human coagulation factor VIII (hFVIII; 320 +/- 39.8 ng/10(6) adipocytes/24 h) in vitro. Based upon successful transduction of adipocytes by SIV vectors carrying the lacZ gene in vivo in mice, the adipose tissue of db/db mice was transduced with SIVhFVIII. There was a transient appearance of human FVIII in mouse plasma (maximum 1.8 ng/ml) on day 11 after the injection. Transcripts of human FVIII transgene and human FVIII antigen also were detected in the adipose tissue by RT-PCR and immunofluorescence, respectively, on day 14. Emergence of anti-human FVIII antibodies 14 days after the injection of SIVhFVIII may explain the disappearance of human FVIII from the circulation. These results suggest that transduction of the adipocytes with vectors carrying the human FVIII gene may be potentially applicable for gene therapy of hemophilia A.

Effects of antiplatelet agents on pulmonary haemodynamic response to fMLP in endotoxin primed rats

BACKGROUND

The interaction between neutrophils and platelets may be important in the modulation of pulmonary haemodynamics under systemic inflammatory conditions. A study was undertaken to examine whether antiplatelet agents inhibit platelet-neutrophil adherence and ameliorate the pulmonary haemodynamic response to fMLP by inhibiting thromboxane release in endotoxin primed lungs. fMLP stimulates neutrophils but not platelets; however, thromboxane synthesis in neutrophils is very low.

METHODS

Rats were pretreated with either cilostazol (300 mg/kg) or aspirin (50 mg/kg) before endotoxin priming (5 mg/kg). Platelets in the lung were identified by fluorescent immunohistochemistry. Platelet-neutrophil adherence was analysed by flow cytometry of the lung vascular flush. The effect of fMLP (10(-6) M) on thromboxane release, lung weight (an indicator of pulmonary vasoconstriction), and lung filtration coefficient was determined in an isolated lung system perfused at a constant pressure difference.

RESULTS

Endotoxin induced platelet accumulation and platelet-neutrophil adherence in the lung capillary were completely inhibited by cilostazol and aspirin while neutrophil recruitment was not affected. The fMLP challenge caused a significant increase in thromboxane B2 levels in endotoxin primed lungs. The fMLP induced decrease in lung weight was enhanced by endotoxin priming (from -4.9 to -63.9 mg, 95% CI of mean difference -99.5 to -10.5 mg, p<0.05). The fMLP induced increase in the lung filtration coefficient was also enhanced by endotoxin priming (from 0.63 to 2.40 mg/min/cm H2O/g, 95% CI of mean difference 1.17 to 2.37 mg/min/cm H2O/g, p<0.05). Treatment with cilostazol and aspirin completely inhibited the enhanced pulmonary haemodynamic response to fMLP.

CONCLUSION

The neutrophil-platelet interaction is of critical importance in the modulation of pulmonary haemodynamics via thromboxane.

Simian lentiviral vector-mediated retinal gene transfer of pigment epithelium-derived factor protects retinal degeneration and electrical defect in Royal College of Surgeons rats

Retinitis pigmentosa (RP) is a heterogenous group of inherited retinal diseases resulting in adult blindness caused by mutations of various genes. Although it is difficult to cure the blindness that results from these diseases, delaying the disease progression may be of great benefit, since the majority of RP diseases are seen in middle age or later. To test a gene therapy strategy for RP using a neurotrophic factor gene, we assessed the effect of simian lentivirus (SIV)-mediated subretinal gene transfer of pigment epithelium-derived factor (PEDF), a potent neurotrophic factor, during the disease progression in Royal College of Surgeons (RCS) rats, a well-accepted animal model of RP. Regional gene transfer via SIV into the peripheral subretinal space at the nasal hemisphere was performed in all animals to monitor site-specific transgene expression as well as the therapeutic effect in each retina. Gene transfer of lacZ and PEDF was observed in the regional pigment epithelium corresponding to the regional gene transfer. Histologically, PEDF gene transfer significantly protected the loss of photoreceptor cells (PCs) corresponding to the regions of the gene transfer, compared to those of control groups during the course of the experiment. The antiapoptotic effect of PEDF on PCs is likely to be a related mechanism, because a significant reduction of terminal dUTP-nicked end labeling-positive PC numbers was found in PEDF-treated eyes compared to those of the control group (P<0.05). PEDF-treated eyes also retained a significant sensitivity to light flash during the experimental course. These findings clearly show that neuroprotective gene therapy using PEDF can protect retinal degeneration and functional defects in individuals with RP.

Simian immunodeficiency virus-based lentivirus vector for retinal gene transfer: a preclinical safety study in adult rats

Although lentivirus vectors hold promise for ocular gene therapy, they also have potential safety issues, particularly in the case of the current human immunodeficiency virus-based vectors. We recently developed a novel lentivirus vector derived from the nonpathogenic simian immunodeficiency virus from African green monkeys (SIVagm) to minimize these potentials. In this preclinical study, we evaluated whether SIV vector could be efficiently and safely applicable to retinal gene transfer by assessing the transgene expression, retinal function and histology over a 1-year period following subretinal injection in adult rats. The functional assessment via electroretinogram after both titers of SIV-lacZ (2.5 x 10(7) or 2.5 x 10(8) transducing units/ml) injection revealed both the dark and light adaptations to soon be impaired, in a dose-dependent manner, after a buffer injection as well, and all of them recovered to the control range by day 30. In both titers tested, the retinas demonstrated a frequent transgene expression mainly in the retinal pigment epithelium; however, the other retinal cells rarely expressed the transgene. Retinas exposed to a low titer virus showed no significant inflammatory reaction throughout the observation period, and also maintained the transgene expression over a 1-year period. In the retinas exposed to a high titer virus, however, mononuclear cell infiltration persisted in the subretinal area, and the retina that corresponded to the injected area finally underwent degeneration by around day 90. No retinal neoplastic lesions could be found in any animals over the 1-year period. We thus propose that SIV-mediated stable gene transfer might be useful for ocular gene transfer; however, more attention should be paid to avoiding complications when administering high titer lentivirus to the retina.

[Pleomorphic adenoma of the lung; report of a case]

A 67-year-old woman was admitted because of an abnormal shadow on the chest X-ray film. Chest computed tomography (CT) film revealed a peripheral mass in the middle lower lobe of the lung. We performed open lung biopsy and diagnosed as a benign epithelial adenoma but not ruled out adenocarcinoma completely by intraoperative examination of frozen sections. We operated right middle lobectomy and mediastinal lymph nodes dissections. Histological examination confirmed pleomorphic adenoma. We examined salivary glands, but didn't find the focus of that. The patient had been well for three years postoperatively.

Physiological properties of periodontal mechanosensitive neurones in the posteromedial ventral nucleus of rat thalamus

Unitary discharges of periodontal mechanosensitive (PM) neurones responding to mechanical tooth stimulation were recorded from the posteromedial ventral nucleus (VPM) of rat thalamus. PM neurones are distributed in the ventromedial area in the rostral two-thirds of the VPM nucleus. Maxillary and mandibular tooth-sensitive neurones are arranged in dorsoventral sequence. Of the PM neurones, 36% were slowly adapting to pressure applied to the tooth and 67% were rapidly adapting. The majority of PM units were sensitive to the contralateral incisor tooth. Response magnitudes of the slowly adapting neurones varied with stimulus direction and were directionally selective to mechanical tooth stimulation. The optimal stimulus direction was labiolingual or linguolabial. Rapidly adapting neurones were directionally non-selective to tooth stimulation. The threshold for mechanical stimulation was <0.05 N. Mean response latencies evoked by electrical stimulation of the peripheral receptive fields were 4.6 ms in the slowly adapting neurones and 5.8 ms in the rapidly adapting neurones.

Correlations between response properties of periodontal mechanosensitive neurones in the primary somatosensory cortex of the rabbit and cortically induced rhythmical jaw movements

The response properties of incisor- and molar-sensitive periodontal mechanosensitive (PM) neurones in the primary somatosensory (SI) cortex of rabbits were examined and rhythmical jaw movements induced by repetitive electrical stimulation of the recording sites of cortical PM neurones were observed. PM units were recorded from the rostromedial (RM) and rostrolateral (RL) areas of the SI cortex. In the RM area, most PMs (85%) were lower incisor-sensitive. Electrical stimulation of the RM area produced chopping-type rhythmical jaw movements. In the RL area, both incisor- and molar-sensitive PM units were recorded, and molar-sensitive units were located more rostromedially than incisor-sensitive units. More than half (66%) of the incisor-sensitive PM units were upper incisor-sensitive. The incidences of sustained-response type units were 8 and 10% for upper incisor- and lower incisor-sensitive units and 28 and 34% for upper molar- and lower molar-sensitive units, respectively. The optimal stimulus directions for the upper molar-sensitive units were predominantly labial or lingual, whereas those for most of the lower molar-sensitive units were lingual. Electrical stimulation of the PM unit-recording sites in the RL area induced grinding-type rhythmical jaw movements. Based on these findings, the lower incisor-sensitive neurones in the RM area of the SI cortex might mainly contribute to a neural network that controls jaw movements during ingestion. Furthermore, the response properties of molar-sensitive cortical neurones might be useful for discriminating the magnitude and direction of the biting force during grinding. Further studies are needed to clarify the role of upper incisor-sensitive neurones in the RL area in triggering grinding-type rhythmical jaw movements.

Hepatic angiomyolipoma: radiologic and histopathologic correlation

We present two cases of hepatic angiomyolipoma. Histologic analysis showed that mature adipose tissue occupied 79.0% of the area on the largest cut surface in the first case and 40.2% in the second case. We suggest that the difference in the ratio of adipose tissue volume to its distribution is reflected on diagnostic images.

Off-line leukapheresis using leukofiltration for active ulcerative colitis: a case report

The method of leukocytapheresis for ulcerative colitis (UC) by using extracorporeal circulation (on-line system) has been reported. To perform leukocytapheresis, we have applied leukocyte elimination filters for blood transfusion to leukocytapheresis without using extracorporeal circulation (off-line leukocytapheresis system). Four hundred milliliters of peripheral blood was collected and reinfused through a leukocyte elimination filter. This procedure was repeated 5 times, and up to 2,000 ml of peripheral blood was treated. This method has been applied once a week for 5 weeks. We applied the off-line leukapheresis system to a 31-year-old male ulcerative colitis patient. As a result, the frequency of defecation and the dose of medicine were effectively decreased, and endoscopic finding was also improved. Because of the absence of complications observed with the on-line system, the off-line leukocytapheresis system that we have applied to the clinical patient is simple, safe, and useful.

Peripheral primitive neuroectodermal tumor of the vulva: report of a case with imprint cytology

BACKGROUND

Peripheral primitive neuroectodermal tumor (PNET) of the vulva is an extremely rare disease, and, to our knowledge, only two cases have been previously reported.

CASE

A 45-year-old woman presented with a mass in the right labium major. Three years after removal of the tumor, she noticed a new lesion in the same place and underwent a partial vulvectomy. The imprint cytology of the recurrent tumor showed a monomorphic appearance, composed of small round cells with scant cytoplasm against a hemorrhagic background. These tumor cells were loosely connective, but rosettelike structures were observed focally. On pathologic examination, the neoplasm was composed of small round tumor cells showing sinusoidal, diffuse or micropapillary growth. Immunohistochemically, the neoplastic cells stained positively for neuron-specific enolase, vimentin and HBA 71 and negatively for cytokeratin, HBA 45 and muscle-specific actin. The morphologic characteristics of the disease were well expressed in the imprint cytology, and this influenced the selection of immunohistochemical studies.

CONCLUSION

Cytologic examination for vulvar tumors, even imprint cytology, can be a useful tool in obtaining an accurate pathologic diagnosis of a rare disease, such as peripheral PNET.

Response properties of periodontal mechanosensitive neurones in the rat trigeminal sensory complex projecting to the posteromedial ventral nucleus of the thalamus

Unitary discharges from periodontal mechanosensitive (PM) neurones responding to mechanical stimulation of the tooth were recorded from the trigeminal sensory complex in the rat brainstem. Of the PM units recorded, 22% were activated by antidromic stimulation of the contralateral (20%) or ipsilateral (2%) posteromedial ventral nucleus of the thalamus. Although thalamic-projecting neurones were recorded extensively throughout the trigeminal sensory complex, they originated most often in the region from the caudal main sensory nucleus to the rostral subnucleus oralis of the trigeminal spinal tract nucleus. The response latencies of the rostral nucleus units to orthodromic stimulation of peripheral receptive fields and antidromic stimulation of the thalamus were significantly shorter than those of the caudal nucleus units. More than half were single-tooth units originating from incisor teeth. They responded continuously when pressure was applied to the tooth. The magnitude of the response varied with the direction of the stimulus. Maximal responses were obtained when the stimulus was applied labiolingually or vice versa. The threshold for mechanical stimulation of the tooth was less than 0.05 N. The rostrocaudal distribution and response properties of thalamic-projecting PM neurones were very similar to those of non-thalamic-projecting PM units that were not activated by antidromic stimulation of the thalamus.

Atherogenic lipoproteins in end-stage renal disease

Cardiovascular mortality is substantially higher in patients with end-stage renal disease (ESRD). Lipoprotein abnormality in ESRD is one of the possible risk factors for advanced atherosclerosis. Uremic dyslipidemia is characterized by increased plasma triglycerides due to elevated very low density lipoprotein (VLDL) and decreased high-density lipoprotein (HDL). Plasma total or low-density lipoprotein (LDL) cholesterol is rarely elevated in hemodialysis patients. The "LDL" by standard assay methods consists of intermediate-density lipoprotein (IDL) and LDL devoid of IDL. Although "LDL" is not increased, IDL is markedly elevated in uremic plasma. We previously showed that aortic stiffness of hemodialysis patients was associated positively with VLDL, IDL, and LDL devoid of IDL and that IDL is the best lipoprotein predictor of aortic stiffness. The IDL level is correlated positively with plasma total cholesterol, triglyceride, and "LDL" levels. Importantly, increased IDL is found in ESRD patients with "normal" "LDL"cholesterol levels, indicating that the target "LDL" level should be lower than that for the general population. More than 40% of hemodialysis patients exceeded the upper limit (15 mg/dL, 95th percentile level) of IDL cholesterol in healthy subjects. Based on a linear relationship between IDL and "LDL," the normal range of IDL cholesterol (<15 mg/dL) corresponds to "LDL" cholesterol by the Friedewald equation below 100 mg/dL in hemodialysis patients. Statins effectively and safely reduce "LDL," including IDL in patients treated with hemodialysis or peritoneal dialysis. The effect of lipid-lowering therapy on cardiovascular mortality in ESRD, however, awaits the results of ongoing prospective trials.

Selective AV nodal vagal stimulation improves hemodynamics during acute atrial fibrillation in dogs

Although the atrioventricular node (AVN) plays a vital role in blocking many of the atrial impulses from reaching the ventricles during atrial fibrillation (AF), a rapid irregular ventricular rate nevertheless persists. The goals of the present study were to explore the feasibility of novel epicardial selective vagal nerve stimulation for slowing of the ventricular rate during AF and to characterize the hemodynamic benefits in vivo. Electrophysiological-echocardiographic experiments were performed on 11 anesthetized open-chest dogs. Hemodynamic measurements were performed during three distinct periods: 1) sinus rate, 2) AF, and 3) AF with vagal nerve stimulation. AF was associated with significant deterioration of all measured parameters (P < 0.025). The vagal nerve stimulation produced slowing of the ventricular rate, significant reversal of the pressure and contractile indexes (P < 0.025), and a sharp reduction in one-half of the abortive ventricular contractions. The present study provides comprehensive evidence that slowing of the ventricular rate during AF by selective ganglionic stimulation of the vagal nerves that innervate the AVN successfully improved the hemodynamic responses.

[Relationship between Noguchi's classification for small adenocarcinomas of the lung and tumor markers in serum]

We evaluated the relationship between Noguchi's classification for small adenocarcinomas of the lung and tumor markers in serum (CEA, Cyfra, SLX, CA 19-9, CA 125). Fifty surgically resected small peripheral adenocarcinomas measuring 2 cm or less in greatest diameter were examined. The tumors were divided into three groups on the basis of Noguchi's classification: group AB of tumors belonging to Noguchi's classification A or B, group C of tumors belonging to Noguchi's classification C, and group DEF of tumors belonging to Noguchi's classification D, E, or F. The level of serum CEA was higher in group DEF (5.9 +/- 7.6 ng/ml) than in group AB (2.3 +/- 2.4 ng/ml) and group C (2.0 +/- 1.3 ng/ml). There were no differences in the levels of the other serum tumor markers among the three groups. The incidences of anormality in serum CEA and Cyfra were higher in group DEF (6/18 and 6/18, respectively) than in group AB (1/7 and 0/7) and group C (1/25 and 1/25). Although a high level of serum CEA or Cyfra is a strong indication that the tumor is Noguchi's classification D, E, or F of pulmonary adenocarcinoma, it is difficult to classify small adenocarcinomas by Noguchi's classification using a serum tumor marker level.

Positive peritoneal cytology in endometrial cancer: enhancement of other prognostic indicators

OBJECTIVE

The goal of this study was to investigate the prognostic significance of positive peritoneal cytology in endometrial cancer.

METHODS

A clinicocytopathological study was performed in 534 patients with endometrial cancer to assess the prognostic value of positive peritoneal cytology. The study population was divided into three groups: a low-risk group (disease limited to the uterus, grade 1, and depth of invasion < or =1/2), a moderate-risk group (disease limited to the uterus, grade 2 or 3, and/or depth of invasion >1/2), and a high-risk group (extrauterine disease). In each group, disease-free survival was compared in the patients who were positive or negative for malignant cells.

RESULTS

The overall incidence of positive peritoneal cytology was 22.3% (119/534). The 5-year disease-free survival of patients positive or negative for malignant cells was 98.1% versus 100% in the low-risk group (n = 250), 77.5% versus 91.3% in the moderate-risk group (n = 211), and 42.9% versus 72.1% in the high-risk group (n = 73). A significant difference was noted in the moderate-risk (P = 0.044) and high-risk (P = 0.015) groups, but not in the low-risk group (P = 0.56).

CONCLUSIONS

Positive peritoneal cytology is not a negative prognostic indicator itself, but it potentiates other prognostic indicators for endometrial cancer. Our findings also suggest that patients with positive peritoneal cytology in the absence of other adverse prognostic factors do not need upstaging.

Device-based change in left ventricular shape: a new concept for the treatment of dilated cardiomyopathy

OBJECTIVE

We tested a unique new device, the Myosplint device (Myocor, Inc, Maple Grove, Minn), which is designed to change left ventricular shape, reduce left ventricular wall stress, and improve left ventricular systolic function.

METHODS

Heart failure was induced in 15 dogs over 27 days by rapid pacing (230 beats/min). Seven animals underwent sham surgery, and 8 animals received 3 transventricular Myosplint devices each. Myosplint devices were tightened to create a symmetric bilobular left ventricular shape and were adjusted to produce a calculated 20% reduction in wall stress. Hemodynamic, 2-dimensional, and 3-dimensional echocardiographic studies were recorded at baseline, immediately after Myosplint placement (acute change), and at 1 month after both groups had a reduced rate (190 beats/min) of pacing designed to maintain heart failure.

RESULTS

The Myosplint group had significant sustained improvements in left ventricular ejection fraction from baseline, to the acute change, to 1 month (19% +/- 5%; 36% +/- 8%; 39% +/- 13%) and reductions of left ventricular end-systolic volumes (73 +/- 9 mL; 34 +/- 5 mL; 42 +/- 12 mL) and end-systolic wall stress by 39% (341 +/- 68 10(3) dynes x cm(- 2) to 206 +/- 28 10(3) dynes x cm(-2)) acutely and 31% (372 +/- 83 10(3) dynes x cm(-2) to 250 +/- 40 10(3) dynes x cm(-2)) at 1 month. There were no significant changes in mitral regurgitation.

CONCLUSION

Application of a Myosplint device to a dilated impaired left ventricle resulted in reduced wall stress and improved left ventricular systolic function that was sustained at 1 month. Device-based shape change is a promising new opportunity to treat patients with dilated cardiomyopathy.

Assessment of LV systolic function in atrial fibrillation using an index of preceding cardiac cycles

The clinical assessment of left ventricular (LV) systolic function during atrial fibrillation (AF) is unreliable and difficult because of beat-to-beat variability. We evaluated an index for the estimation of LV systolic function in AF that is based on the relationship between the preceding (R-R1) and prepreceding (R-R2) R-R intervals. LV Doppler stroke volume (SV), ejection fraction (EF), peak aortic flow rate (AoF) and the maximum value of the first derivative of the LV pressure curve (dP/dt(max)) were evaluated in 13 healthy open-chest dogs during triggered AF. All parameters showed a significantly strong positive linear relationship with the ratio of R-R1/R-R2 (r = 0.65, 0.74, 0.75, and 0.70 for SV, EF, AoF, and dP/dt(max), respectively). The calculated value of LV systolic parameters at R-R1/R-R2 = 1 in the linear regression line showed a good relationship and an agreement with the measured average value of the parameter over all cardiac cycles (SV, 12.1 vs. 12.8 ml; EF, 49.6 vs. 51.2%; AoF, 1.37 vs. 1.48 l/min; and dP/dt(max), 2,323 vs. 2,454 mmHg/s). Using the LV systolic parameters estimated at R-R1/R-R2 = 1 in the linear regression line allows the LV contractile function to be accurately and reproducibly evaluated during AF and obviates the less-reliable process of averaging multiple cardiac cycles.

Genetics of morphogen gradients

The organization of cells and tissues is controlled by the action of 'form-giving' signalling molecules, or morphogens, which pattern a developmental field in a concentration-dependent manner. As the fate of each cell in the field depends on the level of the morphogen signal, the concentration gradient of the morphogen prefigures the pattern of development. In recent years, molecular genetic studies in Drosophila melanogaster have allowed tremendous progress in understanding how morphogen gradients are formed and maintained, and the mechanism by which receiving cells respond to the gradient.

Comparative study of sequential expression of the organizer-related genes in normal Cynops pyrrhogaster embryos and mesodermalized ectoderm

An artificially mesodermalized ectoderm (mE) of early Cynops pyrrhogaster gastrula acquires the organizer property; the mE is able to induce the secondary axis. The expression of organizer-related genes was investigated during the mesodermalizing process of the mE. The expression of C. pyrrhogaster organizer-related genes, such as bra, gsc, lim-1, chd and noggin, were analyzed. Cynops pyrrhogaster shh expression was also investigated. The organizer-related genes were activated by 12 h after the mesoderm-inducing stimulus. It was noted that there was a temporal gap in the expression of each gene. The expression of bra and gsc seemed to be more quickly activated during the mesodermalizing process. While expression of lim-1 and noggin was activated later than that of bra and gsc, lim-1 expression was earlier than chd and noggin expression. Shh expression was activated later than lim-1/noggin. The present study suggests the possibility that the bra/gsc, lim-1, chd, noggin and shh genes are expressed one by one in that order during the mesodermalizing of the presumptive ectoderm. It also indicates that the sequence is not always consistent with that of the whole embryo during normal embryogenesis. The meaning of the discrepancy will be discussed in connection with the cascade of certain genes expressed during the mesodermalizing process.

Müllerian adenosarcoma of the uterus: report of a case with imprint cytology

BACKGROUND

Müllerian adenosarcoma is a rare morphologic variant of uterine sarcoma that, although well described histologically, is scarcely mentioned in the cytologic literature.

CASE

A 75-year-old female was suspected of having atypical endometrial hyperplasia on an endometrial smear. However, subsequent imaging techniques revealed the presence of a bulky, polypoid mass filling the uterine cavity. On pathologic examination of the hysterectomy specimen, the polypoid tumor was diagnosed as mullerian adenosarcoma, homologous, with sarcomatous overgrowth, in which the sarcomatous component was compatible with high grade endometrial stromal sarcoma. Imprint smears of the tumor consisted of two morphologic patterns, sarcomatous and glandular. The sarcomatous tumor cells, with coarse chromatin and relatively scant cytoplasm, formed small aggregates or appeared alone. These cells were semiround or oval and had conspicuous nucleoli. In addition to these observations, small and large clusters of glandular cells with mild atypism were interspersed with the sarcomatous cells.

CONCLUSION

Cytologic examination of müllerian adenosarcoma well reflects its pathologic features.

Analysis of a discrepancy in electron-beam dose comparison between chemical dosimeters and a calorimeter

A 2.1% discrepancy was reported from an electron-beam dose comparison between liquid chemical dosimeters and a water calorimeter. Two methods, depth-dose measurement in a sandwich phantom and the use of a semiempirical depth-dose code EDMULT, were used to analyze the depth-dose distribution in the dosimeters and the calorimeter and to calculate their dose ratio. Results have shown that the discrepancy can be explained by the difference in the effective detection volume.