Development of a generalized pharmacokinetic model to characterize clinical pharmacokinetics of monomethyl auristatin E-based antibody-drug conjugates

AIMS

This study aims to develop a generalized pharmacokinetic (PK) model for monomethyl auristatin E (MMAE)-based antibody-drug conjugates (ADCs) that can simultaneously capture the PK of multiple ADC analytes commonly measured in the clinic.

METHODS

A comprehensive literature review was conducted to collect PK data on MMAE-based ADCs from clinical trials. From each study, PK profiles of total antibody, the ADC, conjugated MMAE, and unconjugated MMAE, were extracted. These data were pooled and dose-normalized to evaluate the generalizability of PK across various ADCs and dose levels. Upon confirming PK generalizability, a generalized PK model for MMAE-based ADCs was developed using the entire dataset. Furthermore, exposure metrics (C max $$ {\mathrm{C}}_{\mathrm{max}} $$ and AUC) reported across the range of doses were combined to establish linear relationships between dose and exposure metrics for MMAE-based ADCs.

RESULTS

A total of 109 PK profiles from 18 distinct MMAE-based ADCs were gathered. The dose-normalized PK profiles supported the generalizability of PK for MMAE-based ADCs. A generalized PK model was developed, which enabled capturing the PK data for 4 ADC analytes across all collected MMAE-based ADCs. A linear relationship between dose and PK exposure metrics was established, enabling the prediction of typical exposure values across different doses for MMAE-based ADCs.

CONCLUSIONS

This study comprehensively analysed clinical PK data from different valine-citrulline (vc)-MMAE-based ADCs. The generalized PK model developed here serves as an important tool for a priori prediction of the PK for multiple ADC analytes in clinical settings and lays the foundation for establishing generalized exposure-response and exposure-toxicity correlations for MMAE-based ADCs.

Whole-Body Pharmacokinetics and Physiologically Based Pharmacokinetic Model for Monomethyl Auristatin E (MMAE)

Monomethyl auristatin E (MMAE) is one of the most commonly used payloads for developing antibody–drug conjugates (ADC). However, limited studies have comprehensively evaluated the whole-body disposition of MMAE. Consequently, here, we have investigated the whole-body pharmacokinetics (PK) of MMAE in tumor-bearing mice. We show that while MMAE is rapidly eliminated from the plasma, it shows prolonged and extensive distribution in tissues, blood cells, and tumor. Highly perfused tissues (e.g., lung, kidney, heart, liver, and spleen) demonstrated tissue-to-plasma area under the concentration curve (AUC) ratios > 20, and poorly perfused tissues (e.g., fat, pancreas, skin, bone, and muscle) had ratios from 1.3 to 2.4. MMAE distribution was limited in the brain, and tumor had 8-fold higher exposure than plasma. A physiological-based pharmacokinetic (PBPK) model was developed to characterize the whole-body PK of MMAE, which accounted for perfusion/permeability-limited transfer of drug in the tissue, blood cell distribution of the drug, tissue/tumor retention of the drug, and plasma protein binding. The model was able to characterize the PK of MMAE in plasma, tissues, and tumor simultaneously, and model parameters were estimated with good precision. The MMAE PBPK model presented here can facilitate the development of a platform PBPK model for MMAE containing ADCs and help with their preclinical-to-clinical translation and clinical dose optimization.

The Hexaco-60, the Dark Triad and Scholastic Cheating

Previous studies have found inconsistent results regarding the personality predictors of scholastic cheating. This study investigated whether personality was a predictor of scholastic cheating using the HEXACO-60 personality inventory and the Dark Triad (DT). A sample of 252 students completed the online questionnaire. Results from a one-way ANOVA showed that scholastic cheating was more common in associate degree/diploma/foundation students and undergraduate students than postgraduate students. Year of study or student status (local or international students) had no effect on scholastic cheating. MANOVA showed that academic qualification, year of study, and student status had no effect on reasons for cheating. A structural equation model (SEM) found that scholastic cheating was positively predicted by unmitigated achievement and psychopathy. Psychopathy emerged as the strongest significant predictor of scholastic cheating. These results supported the view that dark personality is relevant for understanding scholastic cheating.

Sample-to-answer on molecular diagnosis of bacterial infection using integrated lab--on--a--disc

Sepsis by bacterial infection causes high mortality in patients in intensive care unit (ICU). Rapid identification of bacterial infection is essential to ensure early appropriate administration of antibiotics to save lives of patients, yet the present benchtop molecular diagnosis is time-consuming and labor-intensive, which limits the treatment efficiency especially when the number of samples to be tested is extensive. Therefore, we hereby report a microfluidic platform lab-on-a-disc (LOAD) to provide a sample-to-answer solution. Our LOAD customized design of microfluidic channels allows automation to mimic sequential analytical steps in benchtop environment. It relies on a simple but controllable centrifugation force for the actuation of samples and reagents. Our LOAD system performs three major functions, namely DNA extraction, isothermal DNA amplification and real-time signal detection, in a predefined sequence. The disc is self-contained for conducting sample heating with chemical lysis buffer and silica microbeads are employed for DNA extraction from clinical specimens. Molecular diagnosis of specific target bacteria DNA sequences is then performed using a real-time loop-mediated isothermal amplification (RT-LAMP) with SYTO-9 as the signal reporter. Our LOAD system capable of bacterial identification of Mycobacterium tuberculosis (TB) and Acinetobacter baumanii (Ab) with the detection limits 103cfu/mL TB in sputum and 102cfu/mL Ab in blood within 2h after sample loading. The reported LOAD based on an integrated approach should address the growing needs for rapid point-of-care medical diagnosis in ICU.

Human immunogenic T cell epitopes in nucleoprotein of human influenza A (H5N1) virus

1. Two novel HLA-A2.1 specific H5N1 nucleoprotein epitopes(NP373-381 AMDSNTLEL and NP458-466 FQGRGVFEL) capable of activating cytotoxic T-cells in vitro were identified. 2. When the H5N1 nucleoprotein epitopes (NP373-381AMDSNTLEL and NP458-466FQGRGVFEL) were used with the single chain trimer system, they elicited effective cytotoxic T-cell responses against the corresponding nucleoprotein peptide-loaded cells in an HHD transgenic mouse model.

Cerebral hemodynamics and cognitive impairment: baseline data from the RECON trial

OBJECTIVE

To determine whether unihemispheral hemodynamic failure is independently associated with cognitive impairment among participants in the National Institute of Neurological Disorders and Stroke-sponsored, multicenter, randomized clinical trial, Randomized Evaluation of Carotid Occlusion and Neurocognition (RECON).

METHODS

Forty-three patients were randomized into RECON after recent symptomatic carotid artery occlusion and asymmetrically increased oxygen extraction fraction (OEF) by PET (OEF ratio >1.13), indicating stage II hemodynamic failure on the side of occlusion. The PET-positive patients were compared with 28 RECON-enrolled patients who met all clinical and radiographic inclusion/exclusion criteria but had no OEF asymmetry. A multivariable regression compared patients with PET OEF >1.13 or ≤1.13, stratifying by TIA vs. stroke as the qualifying event. The dependent variable was a composite neurocognitive score derived from averaging age-normalized z scores on a test battery that included global and internal carotid artery (ICA) side-relevant hemisphere-specific tests.

RESULTS

There were no differences in demographic, clinical, or radiologic characteristics between the PET-positive and PET-negative patients except for PET OEF asymmetry. The unadjusted average neurocognitive z score was -1.45 for the PET-positive and -1.25 for the PET-negative patients, indicating cognitive impairment in both groups but no difference between them (p = 0.641). After adjustment for age, education, side of occlusion, depression, and previous stroke, there was a significant difference between PET-positive and PET-negative patients among those with TIA as a qualifying event (average z score = -1.41 vs. -0.76, p = 0.040). Older age and right ICA side were also significant in this model.

CONCLUSION

Hemodynamic failure is independently associated with cognitive impairment in patients with carotid occlusion. This finding establishes the physiologic parameter upon which the extracranial-intracranial bypass will be tested.

Toxicity burden score: a novel approach to summarize multiple toxic effects

BACKGROUND

Toxicity data from cancer trials are summarized into a single outcome, dose-limiting toxicity (DLT), which does not account for multiple lower grade toxic effects nor differentiates between toxicity types and gradations within DLT.

METHODS

Toxicity data were summarized into a toxicity burden score (TBS) using a weighted sum. The severity weights were estimated via regression using historical data. We demonstrated the method using historical data from a bortezomib trial and illustrated the advantages of defining DLT based on TBS in a simulated dose-finding trial.

RESULTS

The estimated weights were 0.17, 0.40 and 0.85 for grade 1/2, grade 3 and grade 4 platelets, respectively; 0.19, 0.64, 1.03 and 2.53 for grade 1, 2, 3 and 4 neuropathy, respectively and 0.17 for each grade 3 or higher nonhematologic toxic effects unrelated to treatment. In the simulated trial, the probability of selecting doses above the maximum tolerated dose decreased when using the DLT defined based on TBS.

CONCLUSIONS

TBS is a feasible approach to summarize toxicity. It includes information from the grades and types of multiple toxic effects and can be applied in all phases of drug development. Further efforts should focus on validating the method in a large prospective study before applying it in practice.

Sonographic study of the decidua basalis in early pregnancy loss

OBJECTIVES

To describe the sonographic findings in the decidua basalis layer in spontaneous early pregnancy loss and to compare them with those in normal pregnancy.

METHODS

We reviewed 119 scans at 4-10 weeks' gestation from 110 patients who miscarried clinically at less than 13 weeks' gestation and 132 scans also at 4-10 weeks from 98 patients who had normal uncomplicated term pregnancies. The thickness and echogenicity of the decidua basalis layer were compared between pregnancies which suffered early loss and normal controls.

RESULTS

Relative thinning of the decidua basalis was observed in cases of early pregnancy loss from 5-6 weeks onwards when compared with normal pregnancies. In embryonic pregnancies that subsequently miscarried, the decidua basalis did not show the rising trend in thickness that was observed in normal pregnancies. Shortly before and after embryonic demise, the decidua appeared relatively more echogenic compared with that in normal pregnancy and the placenta showed areas of hypoechogenicity. Embryonic demise was followed by disorganization of the decidual layer, which became difficult to recognize. Pregnancy with an empty sac showed a more gradual trend in the thinning of the decidua basalis, but the uniformity and echogenicity of the layer appeared to be relatively better preserved with time.

CONCLUSION

The decidua basalis layer in pregnancies that are destined to miscarry in the first trimester differs sonographically from that in normal pregnancies. The sonographic differences are suggestive of a defective decidual-placental complex resulting from deficient trophoblastic invasion.

Sonographic study of the decidua basalis in the first trimester of pregnancy

OBJECTIVES

To describe the sonographic appearance of the decidua basalis and its changes in the first trimester of pregnancy.

METHODS

We reviewed images from 159 first-trimester ultrasound examinations in 105 women with uncomplicated pregnancies who later delivered at term. The appearance of the decidua basalis layer and the sonographic changes that it underwent, including in echogenicity and thickness, were analyzed with respect to gestational age.

RESULTS

A distinct decidual layer could be identified consistently at 5-6 weeks' gestation and its thickness peaked at 6-7 weeks. It was seen inconsistently at 8-9 weeks and was not identifiable by 10 weeks. Its appearance changed over time, from a uniformly echogenic layer at 5-6 weeks to a heterogeneous echogenic layer at 7 weeks, corresponding to the histological evidence of trophoblast penetration. The layer then became less echogenic with time until it became unidentifiable.

CONCLUSIONS

There is a window of opportunity in the first trimester for sonographic examination of the decidua. This may allow screening, at an early stage, for conditions that affect the decidua during pregnancy.

Investigation of immunogenic T-cell epitopes in SARS virus nucleocapsid protein and their role in the prevention and treatment of SARS infection

1. A novel HLA-A2.1-specific SARS coronavirus (SARS-CoV) nucleocapsid (N) protein epitope (N220-N228 LALLLLDRL) able to activate cytotoxic T cells in vitro has been identified. 2. When used with a single-chain-trimer system, the SARS-CoV N protein epitope (N220-N228 LALLLLDRL) can stimulate a cytotoxic T-cell response against N-protein expressing cells in the HLA-A2.1K(b) transgenic mouse model.

Zero mode waveguides for single-molecule spectroscopy on lipid membranes

Zero mode waveguides (ZMWs), subwavelength optical nanostructures with dimensions ranging from 50 to 200 nm, have been used to study systems involving ligand-receptor interactions. We show that under proper conditions, lipid membranes will invaginate into the nanostructures, which confine optical excitation to subattoliter volumes. Fluorescence correlation spectroscopy (FCS) was used to characterize the diffusion of fluorescently tagged lipids in liquid-disordered phase 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and gel phase 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) membranes incubated on the nanostructured surface. In contrast to the POPC, DSPC membranes did not appear to enter the structures, suggesting that invagination is dependent on membrane rigidity. Although correlation curves obtained from POPC membranes conformed to previously derived models for diffusion in the evanescent field within the nanostructure, the diffusion constants obtained were systematically lower than expected. The validity of the one-dimensional diffusion model for membrane diffusion is discussed and it is concluded that the erroneous diffusion constants are a result of nontrivial membrane conformation within the ZMWs. Additionally, FCS was used to characterize the fraction of fluorescently labeled tetanus toxin C fragment bound to a ganglioside-populated POPC membrane within the ZMWs. This allowed the determination of the toxin's equilibrium binding constant at a concentration of 500 nM; higher than possible with diffraction-limited FCS. To our knowledge, the results presented here are the first reported for supported lipid bilayers in nanostructured devices. Furthermore, they open the possibility of studying membrane imbedded receptors and proteins at physiological concentrations with single-molecule resolution.

Human papillomavirus type 16 E7 peptide(38-61) linked with an immunoglobulin G fragment provides protective immunity in mice

OBJECTIVE

To explore whether the recombinant protein (Human papillomavirus (HPV) type16 E7 peptide(38-61) linked with an immunoglobulin G fragment) will generate protective immunity in mouse model.

METHODS

In our study, we combined the HPV16 E7 peptide(38-61) with a murine IgG heavy chain constant region to construct a chimeric protein compound, which was highly expressed as inclusion bodies in a bacterial expression system with Escherichia coli. The purified chimeric protein was injected into C57BL/6 mice and the efficiency of the chimeric vaccine candidate was evaluated by antibody response assay, T cell proliferation assay, CTL assay, tumor challenge assay and therapeutic experiment.

RESULTS

The chimeric vaccine candidate was able to induce anti-HPV antibodies as well as to elicit HPV16 E7-specific CTLs and T cell proliferation in a pre-clinical mouse model. It was also able to effectively protect mice against the challenge of HPV16-positive tumor cells, and to eradicate HPV16-expressing tumors in mice.

CONCLUSIONS

The chimeric protein vaccine can induce E7-specific immune responses and protect mice against challenge of HPV16-positive tumor, even eradicate developed tumor. The results indicated a possibility to use the chimeric protein vaccine to protect human against HPV infection.

Value of image-guided needle aspiration cytology in the assessment of pelvic and retroperitoneal masses. A study of 112 cases

OBJECTIVE

To evaluate the diagnostic value of the noninvasive method of image-guided needle aspiration cytology (NAC) in the assessment of radiologically detected pelvic and retroperitoneal space-occupying lesions (excluding the pancreas, kidney and adrenal).

STUDY DESIGN

NAC was performed under computed tomographic or ultrasound guidance on 112 patients suspected of having a pelvic or retroperitoneal mass. Cytologic examination was performed on site after staining smears with the Papanicolaou method. In addition, air-dried smears, fixed smears, filter preparations from needle washings and cell blocks were studied. The NAC diagnosis was supported by examining cell blocks; further support was obtained with a tissue biopsy in some cases. Additionally, pertinent immunoperoxidase and/or histochemical studies were done.

RESULTS

Eighteen cases were diagnosed as inflammatory lesions, 17 cases consisted of normal cellular elements, and 12 cases showed scanty material and were considered unsatisfactory/inadequate for a diagnosis. Five cases were suspicious for malignancy, and in 39 cases metastatic tumors were diagnosed from a previously known primary. Thirteen cases were diagnosed as lymphoma, and in 8 cases a diagnosis of soft tissue sarcoma was made. There were no false positive diagnoses of malignancy. Cell block preparations and immunohistochemistry were helpful with tumor typing, although lymphoma subtyping and soft tissue tumor typing generally required open biopsy.

CONCLUSION

NAC, as the first-line investigation, is not only useful in the diagnosis of space-occupying lesions of the pelvic and retroperitoneal region but can also help in choosing appropriate management. The technique is most useful in diagnosing metastases but is also helpful in excluding malignancy in some cases and in suggesting diagnoses of lymphomas and soft tissue tumors.

Three-dimensional vibration analysis of a torus with circular cross section

The free vibration characteristics of a torus with a circular cross section are studied by using the three-dimensional, small-strain, elasticity theory. A set of three-dimensional orthogonal coordinates system, comprising the polar coordinate (r, theta) at each circular cross section and the circumferential coordinate phi around the ring, is developed. Each of the displacement components u(r), v(theta), and w(phi) in the r, theta, and phi directions, respectively, is taken as a product of the Chebyshev polynomials in the r direction and the trigonometric functions in the theta and phi directions. Eigenfrequencies and vibration mode shapes have been obtained via a three-dimensional displacement-based extremum energy principle. Upper bound convergence of the first seven eigenfrequencies accurate to at least six significant figures is obtained by using only a few terms of the admissible functions. The eigenfrequency responses due to variation of the ratio of the radius of the ring centroidal axis to the cross-sectional radius are investigated in detail. Very accurate eigenfrequencies and deformed mode shapes of the three-dimensional vibration are presented. All major modes such as flexural thickness-shear modes, in-plane stretching modes, and torsional modes are included in the analysis. The results may serve as a benchmark reference for validating other computational techniques for the problem.

Reversible MRI changes of hypothalamus in a multiple sclerosis patient with homeostatic disturbances

Multiple sclerosis (MS) patients occasionally present with homeostatic disturbances suggestive of hypothalamic dysfunction; however, the hypothalamus often appears normal on imaging, apart from confirmation in a few necropsy studies. In this article we describe a Chinese woman with atypical clinical presentation. She presented with relapsing symptoms and signs consistent with hypothalamic dysfunction including hyperprolactinema, syndrome of inappropriate secretion of anti-diuretic hormone (SIADH), hypersomnolence and temperature dysregulation. Serial MRI depicted the atypical reversible changes in the hypothalamus, correlating with the observed homeostatic abnormalities.

Diagnostic value of image-guided needle aspiration cytology in the assessment of vertebral and intervertebral lesions

The aim of this study was to evaluate the diagnostic value of the noninvasive method of image-guided needle aspiration cytology (NAC) in the assessment of radiologically detected vertebral and intervertebral space-occupying lesions. NAC was performed under computed tomographic (CT) guidance on 70 patients suspected of having a vertebral or intervertebral lesion. Cytologic examination was performed on site after staining smears with the Papanicoloau method. In addition, air-dried smears, fixed smears, filter preparations from needle washings, and cell blocks were studied. The NAC diagnosis was supported by examining cell blocks, which showed the reliability of histologic architecture; further support was obtained with a tissue biopsy in some cases. Additionally, immunoperoxidase and/or histochemical studies were done. Ten cases were diagnosed as inflammatory/degenerative lesions, and in 2 cases a diagnosis of neurofibroma was made. Twelve cases consisted of normal cellular elements, 7 cases were unsatisfactory/inadequate for diagnosis, and 4 cases were suspicious for malignancy. In 32 cases, a variety of metastatic tumors were diagnosed, while in 3 cases, a diagnosis of chordoma was made. Based on our study, we feel that NAC, as a first line of investigation, is not only useful in the diagnosis of space-occupying lesions of vertebral and intervertebral regions, but can also help in deciding on appropriate management. Also, histologic architecture from cell blocks can be correlated with cytology, and such material can be used for histochemical and immunomarker studies.

Tumefactive demyelinating lesions by combined perfusion-weighted and diffusion weighted imaging

Tumefactive demyelinating lesion may sometimes mimic intracranial neoplasm or abscess and pose a diagnostic problem both clinically and radiologically. The diagnosis is even more complicated since multiple sclerosis is relatively uncommon among Chinese and due to low incidence of oligoclonal protein in the cerebrospinal fluid. We present a Chinese lady with tumefactive demyelinating lesion, which mimic cystic neoplasm and cerebral abscess. The use of perfusion and diffusion weighted imaging obviated unnecessary surgical biopsy.

Digital subtraction in gadolinium-enhanced MR imaging of the brain: a method to reduce contrast dosage

The aim of the study was to investigate the feasibility of using digital subtraction in contrast-enhanced MR imaging of the brain to reduce the MR contrast dosage without jeopardizing patient care. Fifty-two patients with intracranial lesions, either intra-axial or extra-axial, detected by computerized tomography were selected for contrast-enhanced MR imaging with half-dose and full-dose of gadopentetate dimeglumine. The half-dose unsubtracted, full-dose unsubtracted, and half-dose subtracted MR images were visually assessed by counting the number of enhancing brain lesions in the images and quantitatively analyzed by computing their lesion contrast-to-background ratios (CBR). The visual conspicuity of the half-dose subtracted MR images was comparable to that of the full-dose unsubtracted MR images ( p>0.05), whereas the CBR of the half-dose subtracted images was approximately two to three times higher than that of the full-dose unsubtracted images. The half-dose subtracted T1-weighted spin-echo images might be able to replace the conventional standard-dose T1-weighted spin-echo images in MR imaging of the brain.

Evaluation of cerebral abscesses by diffusion-weighted MR imaging and MR spectroscopy

Cerebral abscess may sometimes mimic necrotic tumor and cystic metastases both clinically and radiologically. The imaging findings may be indistinguishable on conventional magnetic resonance imaging. Although recent studies have shown that cerebral abscess displays restricted diffusion on diffusion-weighted imaging (DWI), it is not pathognomic. Necrotic tumor and cystic metastases may occasionally have restricted diffusion on DWI. Since the urgency of surgical intervention and approach of surgery is different, MR Spectroscopy may be used in conjunction with DWI in establishing the correct diagnosis.

Late temporal lobe necrosis in patients with nasopharyngeal carcinoma: evaluation with combined multi-section diffusion weighted and perfusion weighted MR imaging

Late temporal lobe necrosis is a well-known and serious complication in patients with nasopharyngeal carcinoma (NPC) following radiotherapy. Owing to the close proximity to the skull base, the medial temporal lobes are inevitably included in the target volume of irradiation. Patients with NPC provide a unique opportunity in study of delay radiation effect in normal human brain. The objective of this study was to evaluate late temporal lobe radiation injury by combined multi-section diffusion weighted and perfusion weighted MR imaging. We prospectively studied 16 patients with typical clinical symptoms of late temporal lobe necrosis or other abnormalities in the temporal lobes incidentally detected by conventional MR imaging. All patients had a previous history of radiotherapy for histologically proven NPC. Conventional T1- and T2-weighted images, fast gradient echo with echo-planar diffusion-weighted and perfusion-weighted MR imaging were performed. Apparent diffusion coefficient (ADC) map and relative cerebral blood volume (rCBV) map were computed via commercially available software. MR diffusion and perfusion images were then analyzed and graded by two independent observers with focusing on the diffusion and perfusion mismatch. The temporal lobe lesions displayed marked high diffusion on the ADC map. The rCBV map also revealed marked hypoperfusion in these temporal lobe lesions in all patients. The areas of abnormality on the rCBV map were significantly larger than the lesions on the ADC map in 14 patients (observer 1) and 13 patients (observer 2). Since late temporal lobe necrosis is probably caused by damage of the endothelium of vessels and ischemia, perfusion and diffusion mismatch might imply injured tissue but potentially salvageable brain tissue. A mismatch may be potentially used to predict the response to treatment in-patients with late temporal lobe necrosis.

Idiopathic pulmonary artery aneurysm: digital subtraction pulmonary angiography grossly underestimates the size of the aneurysm

Pulmonary artery aneurysm is a rare disease entity. The majority of cases are associated with congenital cardiovascular diseases, infection, and trauma; idiopathic pulmonary artery aneurysm is extremely rare. Although conventional and digital subtraction pulmonary angiography remains as the imaging modality of choice for the pulmonary vessels, it is invasive and sometimes may be inaccurate. With the advent of spiral computed tomographic angiography (CTA), pulmonary artery aneurysm can be diagnosed noninvasively and accurately. We report a case of a 68-year-old man with idiopathic pulmonary artery aneurysm of the descending branch of right pulmonary artery where the true caliber of the aneurysm was significantly underestimated in the digital subtraction pulmonary angiography. The literatures of this rare condition are reviewed with the emphasis on the application of CTA in this disease.

Spontaneous intracranial hypotension with diffuse dural enhancement of the spinal canal and transient enlargement of the pituitary gland

Spontaneous intracranial hypotension is a rare phenomenon characterized by postural headache, neck rigidity, nausea and vomiting. Imaging findings on magnetic resonance imaging (MRI) is characteristic with diffuse intracranial pachymeningeal thickening and enhancement following intravenous gadolinium. We present a case of spontaneous intracranial hypotension with two unusual imaging findings; pachymeningeal enhancement of the spinal canal and enlargement of the pituitary gland in addition to the diffuse intracranial pachymeningeal enhancement. In this case report, we will discuss the clinical features, MRI findings and underlying pathophysiology of this rare condition.

Diffusion-weighted MR imaging of the liver: distinguishing hepatic abscess from cystic or necrotic tumor

BACKGROUND

We evaluated the ability of diffusion-weighted (DW) magnetic resonance (MR) imaging to differentiate between hepatic abscess and cystic or necrotic liver tumor.

METHODS

DW MR imaging was performed in 18 patients who had liver masses with large cystic or necrotic cavities detected by computed tomography or ultrasonography. The final diagnoses were pyogenic abscess (five cases), fungal abscess (one), hepatocellular carcinoma (five), cystic metastasis (four), and hepatic cyst (three). Signal intensities on the DW images and apparent diffusion coefficient (ADC) maps were noted. ADCs in all lesions were calculated and compared with Student's t test.

RESULTS

All lesions, except hepatic cysts, showed either heterogeneous or homogeneous rim enhancement on postgadolinium images. All abscess cavities showed hyperintensity on DW images and hypointensity on ADC maps. Conversely, the cystic or necrotic portions of all tumors showed hypointensity on DW images and hyperintensity on ADC maps. The mean ADCs (mm(2)/s) were 0.67 +/- 0.35 x 10(-3) in hepatic abscess, 2.65 +/- 0.49 x 10(-3) in cystic or necrotic tumor, 2.93 +/- 0.52 x 10(-3) in hepatic cyst, and 1.98 +/- 0.37 x 10(-3) in normal liver parenchyma.

CONCLUSION

DW MR imaging, with the help of ADCs, may be a useful noninvasive imaging technique in differentiating hepatic abscess from cystic or necrotic tumor.

MR diffusion-weighted imaging of kidney: differentiation between hydronephrosis and pyonephrosis

The objective of the study was to evaluate the capability and reliability of the magnetic resonance (MR) diffusion-weighted imaging (DWI) in differentiation between hydronephrosis and pyonephrosis. Single-shot echoplanar MR diffusion-weighted imaging was performed in 12 patients who had dilatation of the renal pelvis and calyces detected by ultrasonography (US). Microbiological tests confirmed that there were four cases of pyonephrosis and eight cases of hydronephrosis. Signal intensities of the collecting (pelvicalyceal) systems on the diffusion-weighted images and apparent diffusion coefficient (ADC) maps were noted. ADC values of the pelvicalyceal system in all patients were computed and compared using Student's t test. On diffusion-weighted images, the pelvicalyceal system of the hydronephrotic kidney was hypointense while the pelvicalyceal system of the pyonephrotic kidney was markedly hyperintense. The mean ADCs of the hydronephrotic and pyonephrotic renal pelvis were 2.98 +/- 0.65 x 10(-3) and 0.64 +/- 0.35 x 10(-3) mm(2)/s, respectively. The extremely low ADC of the renal pelvis of the pyonephrotic kidney accounted for its signal hyperintensity on diffusion-weighted images as well as signal hypointensity on ADC maps. In conclusion, the MR diffusion-weighted imaging may be a reliable tool to differentiate pyonephrosis from hydronephrosis.

Reduction of radiation dose to patients undergoing barium enema by dose audit

Nowadays, new fluoroscopic machines are usually equipped with a dose-area product (DAP) meter for dose measurement. In our hospital, DAP meters have been used in the Diagnostic Radiology Department for dose audit since June 1997. Demographic patient data, name of radiologist, fluoroscopic duration and DAP readings of every case were recorded by radiographers. In early 1999, questionnaires were distributed to radiologists who had performed fluoroscopic examinations during the auditing period. 23 radiologists with varying years of experience completed the questionnaire and their practice was analysed. Since familiarization with the examination technique would affect radiologists' practice, these radiologists were divided into two groups for analysis. Radiologists with less than 3 years of experience were grouped together as junior radiologists, whilst others were grouped as senior radiologists. Results of the questionnaire indicated that radiologists generally found DAP meters useful for dose evaluation in the process of technique refinement. Radiologists aware of being under continuous surveillance of their practice showed significant reduction of doses (junior radiologists 25%, p<0.005; senior radiologists 36%, p<0.05) and fluoroscopic times (junior radiologists 36%, p<0.001; senior radiologists 18%, p<0.05) compared with radiologists who were unaware that they were under surveillance but with similar radiological experience. This effect is believed to be because of increased awareness of radiation dose through audit. In addition, this "audit effect" may also affect junior radiologists in decision-making regarding the number of radiographs (p<0.05), but no effect was found for senior radiologists (p>0.5).

Primary multifocal leptomeningeal gliomatosis

A 23-year-old female university student was presented with recent onset of non-specific headache and dizziness. She had no neurological deficit on neurological examination and magnetic resonance imaging of the brain revealed diffuse enhancement in the basal cisterns and cerebral sulci. She was treated as tuberculous meningitis but she did not improve and developed respiratory arrest. Autopsy showed primary multifocal leptomeningeal gliomatosis.

Sequential designs for phase I clinical trials with late-onset toxicities

Traditional designs for phase I clinical trials require each patient (or small group of patients) to be completely followed before the next patient or group is assigned. In situations such as when evaluating late-onset effects of radiation or toxicities from chemopreventive agents, this may result in trials of impractically long duration. We propose a new method, called the time-to-event continual reassessment method (TITE-CRM), that allows patients to be entered in a staggered fashion. It is an extension of the continual reassessment method (CRM; O'Quigley, Pepe, and Fisher, 1990, Biometrics 46, 33-48). We also note that this time-to-toxicity approach can be applied to extend other designs for studies of short-term toxicities. We prove that the recommended dose given by the TITE-CRM converges to the correct level under certain conditions. A simulation study shows our method's accuracy and safety are comparable with CRM's while the former takes a much shorter trial duration: a trial that would take up to 12 years to complete by the CRM could be reduced to 2-4 years by our method.

Rapid spontaneous resolution and redistribution of acute subdural hematoma in a patient with chronic alcoholism: a case report

We report a case of a 54-year-old man who had documented traumatic acute subdural hematoma. He suffered from a transient episode of confusion and a follow-up CT scan of brain 6 h after the initial scan showed resolution and redistribution of the subdural hematoma. In this case report, we review the literature for the underlying pathophysiology of this uncommon phenomenon.

Evaluation of therapeutic effectiveness of transarterial chemoembolization for hepatocellular carcinoma: correlation of dynamic susceptibility contrast-enhanced echoplanar imaging and hepatic angiography

The objective of this study was to evaluate the therapeutic effectiveness of transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) with dynamic susceptibility contrast-enhanced magnetic resonance imaging (DSC-MRI). Seventeen patients with histopathologically proven HCC were included in this study. All patients underwent MR examinations with conventional T1- and T2-weighted images, gadolinium-enhanced images, and DSC-MRI before TACE treatment. Hepatic blood volume (HBV) maps were reconstructed from the time-intensity curves. The same MRI sequences and techniques were repeated 24 h and 6 weeks after TACE. Serial changes in tumor perfusion on HBV maps were correlated with vascularity in hepatic angiography. All tumors were hypointense on T1-weighted images and hyperintense on T2-weighted images. Heterogeneous enhancement was observed in all tumors before and immediately after TACE. Hyperperfusion was noted in most of the tumors on HBV map before TACE and moderate to marked hypoperfusion following TACE. The degree of tumor perfusion on HBV map correlated well with the vascularity in angiography. In conclusion, the noninvasive nature of DSC-MRI is useful to evaluate the effectiveness of TACE. Invasive procedures, such as angiography, are seldom necessary.

Radionecrosis of the temporal lobe: dynamic susceptibility contrast MRI

We examined nine patients with histologically proven nasopharyngeal carcinoma (NPC), treated with radiotherapy, using dynamic susceptibility contrast MRI (DSC-MRI). In eight there was clinical evidence of radionecrosis of the temporal lobe, and one was examined for local recurrence in the nasopharynx. All patients had either high-signal finger-like or cystic lesions in the temporal lobes on T2-weighted images. Heterogeneous contrast enhancement occurred in all patients. Relative regional cerebral blood volume (rrCBV) mapping revealed marked hypoperfusion in all patients. One underwent bilateral temporal lobectomy and radionecrosis was confirmed histologically.

Breath-hold 3D gadolinium-enhanced subtraction MRA in the detection of transplant renal artery stenosis

AIMS

The purpose of this study was to assess the value of breath-hold 3D gadolinium-enhanced subtraction magnetic resonance angiography (GD-MRA) in the detection of transplant renal artery stenosis (TRAS).

PATIENTS AND METHODS

Seven patients with suspected post-transplant renal artery stenosis were studied. GD-MRA was performed at 1.5T with a 3D fast spoiled gradient recalled echo (FSPGR) pulse sequence. Before injection of contrast medium, the 3D pulse sequence was performed to obtain a set of non-contrast images for subtraction purposes. Dynamic 3D imaging was performed simultaneously with the bolus injection of 40 ml of gadopentetate dimeglumine. Angiographic images were reconstructed using the Advantage Window workstation (version 2.0 GE Medical Systems) and subtraction was made with the pre-contrast image data. Any signal intensity cut-off or narrowing of more than 50% was regarded as significant stenosis. Ultrasound Doppler (USD) study was performed with both colour and spectral studies. Peak systolic velocity (PSV) of greater than 2.0 m/s and acceleration time (AT) greater than 120ms was regarded as positive for TRAS. These were then compared with the digital subtraction angiography (DSA) as the gold standard.

RESULTS

A total of nine examinations performed in seven patients were included in the analysis. MRA correlated with the DSA findings in eight examinations, with one false negative. USG correlated with DSA in six examinations, with two false negative and one false positive case.

CONCLUSION

In our opinion, GD-MRA is a promising and non-invasive technique in the detection of TRAS.

Hypertrophic olivary degeneration following surgical excision of brainstem cavernous hemangioma: a case report

Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubo-olivary pathway. It is distinguished from other types of neuronal degeneration in that hypertrophy, rather than atrophy, takes place in the neurons in the inferior olivary nucleus. Prior to the invention of Magnetic Resonance Imaging (MRI), HOD was difficult to be detected, and a firm diagnosis could only be made at autopsy. We present a case of bilateral HOD following surgical excision of a cavernous hemangioma in the brainstem. The literature and imaging findings of this uncommon condition are reviewed.

Detection of hepatic tumor perfusion following transcatheter arterial chemoembolization with dynamic susceptibility contrast-enhanced echoplanar imaging

The aim of the study was to evaluate the usefulness of the magnetic resonance (MR) perfusion maps in the detection of liver tumor perfusion following transcatheter arterial chemoembolization (TACE). MR dynamic susceptibility contrast-enhanced imaging was performed in 12 patients with 10 confirmed hepatocellular carcinoma and 2 confirmed hepatic metastasis using single-shot echoplanar pulse sequence. Time-intensity curves for all hepatic tumors showed a transient signal drop and the hepatic blood volume (HBV) maps were reconstructed. On the HBV maps, most tumors (80%) demonstrated hyperperfusion before TACE and hypoperfusion following TACE. The site and the degree of residual hyperperfusion within the tumor on the HBV maps correlated well with the areas of hypervascularity on the angiograms. In conclusion, the MR perfusion maps can be a promising technique for detecting the perfusion of the residual tumor tissue following TACE.

Fine-needle aspiration cytology of soft-tissue calcinosis presenting as an enlarging mass in the chest wall

Calcinosis cutis is an uncommon condition, and calcific deposits in patients with end-stage renal disease are now somewhat rare, due to improvement in management. Since calcific deposits may clinically resemble a tumor, it is feasible to investigate them by fine-needle aspiration cytology (FNAC). A 52-yr-old male with a history of end-stage renal failure presented with a 2-cm mass in the left chest wall. Within 6 mo the mass enlarged to nearly four times its original size. In view of clinical suspicion of malignancy, FNAC was performed. Cytopreparations showed abundant calcium, indicative of soft-tissue calcinosis. The case is interesting, since the known history of end-stage renal failure enabled the FNAC diagnosis of soft-tissue calcinosis.

A Chinese cultural perspective of nursing care behaviours in an acute setting

This study carried out in Hong Kong, identified 29 Chinese patients' perceptions of the importance of nursing care behaviours in an acute setting using a Chinese language translated version of the CARE-Q instrument. Patients ranked items concerned with 'giving the patients' treatments and medication on time' as the most important and 'sits down with the patient' as the least important. Comparisons are made with the results from other cultures and specific Chinese cultural interpretations are drawn to provide direction for nursing care of Chinese patients in Hong Kong and worldwide.

Fine-needle aspiration cytology of malignant retroperitoneal paraganglioma

The cytologic findings in a fine-needle aspiration sample are described from a large retroperitoneal mass in a 56-yr-old male. The aspiration was performed under CT guidance using a 22-gauge needle, maintaining negative pressure. For cytologic study, on-site smears were prepared and stained by the Papanicolaou method. Additionally, cytospin, filter preparations, cell blocks from the aspirate, histology, and electron microscopy of the tumor tissue were performed. Also, immunodiagnostic staining for neuron-specific enolase (NSE), chromogranin, S-100 protein, vimentin, HMB45, cytokeratin, and Grimelius preparation was performed on cytologic and histologic material. The cytologic material was characterized by cords, suggestive acinar structures, and small follicle-like clusters of cells, while cell blocks from the aspirate showed oval or spindle-shaped nuclei with a somewhat fasciculated appearance. However, sections from the tumor tissue showed an organoid "zellballen" pattern. The nuclei were round, oval, spindly, and epithelioid, with moderate to scanty cytoplasm, smooth nuclear membranes, fine, evenly dispersed chromatin, slight hyperchromasia, and mild pleomorphism. No intranuclear vacuoles were seen. Positive immunohistochemical staining for NSE, chromogranin, and Grimelius preparation was noted in the tumor cells, while staining for vimentin, HMB45, and cytokeratin was negative. Electron microscopy of the tumor tissue revealed the presence of variable numbers of round, membrane-bound, electron-dense neurosecretory granules. The cytohistologic and ultrastructural findings are presented, as well as the results of immunodiagnostic staining which helped in the diagnosis of retroperitoneal paraganglioma, an infrequently reported tumor.

Gas-liquid chromatographic properties of positional isomers of methyl thia, selena, and tellura laurate analogs

Gas-liquid chromatographic analyses of three complete series of synthetic positional isomers of methyl thia, selena, and tellura laurate analogs were carried on a nonpolar (SE-30) and a polar (SP-2330) stationary phase. The average ECL (equivalent chain length) values of the thia, selena, and tellura laurate on SE-30 stationary phase were 13.8, 14.8, and 15.7, respectively, while on SP-2330 the average values for the same series were 17.1, 19.0, and 19.1, respectively. Positional isomers with the heteroatom at the 2-position exhibited the lowest ECL values, while those with the heteroatom at the omega-1 position gave the highest ECL values and were readily separated from the other positional isomers of the same series of analogs by this technique.

Central neurocytoma occurring in the thalamus: CT and MRI findings

A case of central neurocytoma occurring in the thalamus, confirmed by electron microscopy and immunohistochemistry, is reported. Computed tomography demonstrated a hypodense mass with an irregular margin arising from the right thalamus, extending into the lateral ventricle and crossing the midline. It contained areas of calcification and showed slight enhancement after contrast injection. On magnetic resonance imaging (MRI) scan, the tumour was hypointense to the brain in T1-weighted images and was heterogeneously hyperintense to the brain in T2-weighted images.

Evaluation of skull base erosion in nasopharyngeal carcinoma: comparison of plain radiography and computed tomography

Over a period of 16 months, a total of 175 patients with newly diagnosed nasopharyngeal carcinoma (NPC) were evaluated with plain radiography and computed tomography (CT) of nasopharynx and base of skull. 54 of 175 patients (30.9%) had CT evidence of skull base erosion. Plain radiography failed to demonstrate the skull base erosion in 22 of 54 patients (40.7%) and underestimated the extent of bony involvement in another 21 patients (38.9%). In 14 of 54 patients (25.9%), there was also false suspicion of bony erosion in the plain films in one or more regions of the skull base which was not substantiated by CT and subsequent clinical course. The present study shows that plain radiography lacks sensitivity and specificity in detecting skull base erosion by NPC. CT evaluation of NPC patients should include thin CT sections of base of skull for detection of subtle bone erosion, and this would allow better decision concerning the shielding of the pituitary-hypothalamic axis during radiotherapy for improvement in therapeutic ratio. For the investigation of individuals highly suspicious of harboring NPC, even when the plain radiography is negative, CT should still be performed as this may give the only clue to the presence of a small submucosally spreading NPC.

Treatment of acute cortical infarct with intravenous glycerol. A double-blind, placebo-controlled randomized trial

BACKGROUND AND PURPOSE

This clinical trial investigates the effectiveness of intravenous glycerol therapy in patients with acute cortical infarction in whom intracerebral hemorrhage was rigorously excluded.

METHODS

Within 48 hours of symptoms from their first ischemic stroke, 113 hospital inpatients were randomized into the trial, provided that hemorrhage was excluded by computed tomography and informed consent was obtained. Patients were stratified into alert, semicoma, and coma groups using the Glasgow Coma Scale. Treatment was allocated according to a double-blind, randomized protocol; 56 patients received 500 mL of 10% glycerol in saline over 4 hours on 6 consecutive days, and 57 patients received corresponding placebo treatment with saline. Using a variety of objective scoring systems, patient follow-up was up to 6 months.

RESULTS

Corresponding measures of outcome in the glycerol and placebo groups were similar. At 6 months, respective mortality rates were 17 of 56 and 16 of 57, and mean +/- SD improvements in scores were 9.98 +/- 14.40 vs 10.51 +/- 12.68 (long-term), 1.12 +/- 7.20 vs 1.57 +/- 6.30 (prognostic), -1.94 +/- 5.53 vs -2.06 +/- 5.34 (Glasgow Coma Scale), and 21.72 +/- 23.40 vs 11.94 +/- 18.10 (Barthel Index rating in survivors). Hemolysis (generally subclinical) was the only adverse effect.

CONCLUSIONS

There was no clinically or statistically significant difference in outcome between the groups; a trend toward greater functional recovery among survivors was evident after treatment with glycerol.

Computed tomography evaluation of neck node metastases from nasopharyngeal carcinoma

PURPOSE

To study the role of computed tomography in the pre-therapy evaluation of nasopharyngeal carcinoma.

METHODS AND MATERIALS

The computed tomography of 119 new patients of nasopharyngeal carcinoma were evaluated independent of clinical findings for neck node metastases, and then compared with clinical findings. Contrast enhanced axial scans were obtained at 5 mm intervals with the infraorbitomeatal line parallel to the gantry. Scans were obtained from the supra-sellar cistern to the C5 or C6 vertebra for the evaluation of the base of skull, nasopharynx, paranasopharyngeal space and the upper and mid neck.

RESULT

The present study confirmed the disparity of nodal extent documented by clinical palpation and computed tomography. Of the 37 patients who have no clinically palpable node (N0), computed tomography showed nodal involvement in 11 (29.7%) of them, and they were up-staged from N0 to N1. Computed tomography showed multiple or bilateral nodes in seven (58.3%) of the 12 patients with AJC N1 disease and they were hence up-staged to N2. All together, there were 28 (23.5%) patients who have no computed tomography evidence of nodal involvement by tumor. In agreement with clinical experience, the most commonly involved nodal groups were the upper internal jugular and upper spinoaccessary, followed by the lateral retropharyngeal. The percentage of nodes which were not clinically palpable was roughly the same for different regions (15-30%), except, as expected, that all the retropharyngeal nodes were not palpable. The risk of harboring retropharyngeal node was proportional to the size of the largest node in the ipsilateral neck.

CONCLUSION

A significant proportion of patients with clinically negative neck (N0) or AJC N1 disease will be upstaged by computed tomography, thus supporting its routine use in pre-therapy evaluation of nasopharyngeal carcinoma.

Treatment of acute cerebral hemorrhage with intravenous glycerol. A double-blind, placebo-controlled, randomized trial

BACKGROUND AND PURPOSE

Hitherto, treatment of acute cerebral hemorrhage with intravenous glycerol has not been evaluated in rigorous clinical studies with sufficient patient numbers.

METHODS

We undertook a double-blind, stratified and randomized, placebo-controlled clinical trial. Only patients with a first stroke admitted to the hospital within 24 hours after onset of symptoms were recruited, provided computed tomography confirmed hemorrhage and informed consent was obtained. After stratification into alert, semicoma, and coma subgroups using the Glasgow Coma Scale, 107 patients received active treatment (500 ml of 10% glycerol in saline by intravenous infusion over 4 hours on 6 consecutive days) and 109 were given corresponding saline treatment. Using a variety of objective scoring systems, patients were followed up for up to 6 months.

RESULTS

At follow-up, all measures of outcome in the treated and control groups were very similar. At 6 months, respective mortality rates were 37 of 107 and 33 of 109. Corresponding mean +/- SD improvements in Scandinavian Stroke Study Group scores were 8.35 +/- 16.9 versus 11.55 +/- 15.6 (long-term) and 0.64 +/- 7.3 versus 2.40 +/- 6.9 (prognostic), and improvements in the Barthel Index ratings were 10.72 +/- 24.7 versus 13.95 +/- 23.3, respectively. Glasgow Coma Scale score improvements in the survivors were 0.81 +/- 1.5 and 1.16 +/- 1.7 in the treated and control groups, respectively. Hemolysis (generally subclinical) was the only adverse effect of glycerol noted.

CONCLUSIONS

In the absence of any clinically or statistically significant difference in outcome between the treated and control groups, this trial provides no justification for glycerol therapy following acute cerebral hemorrhage.

Computed tomography of paranasopharyngeal spaces: normal variations and criteria for tumour extension

In 137 normal CT scans of the nasopharynx, the parapharyngeal spaces at the nasopharynx level were asymmetrical in 30%. Their difference in width and distance from the midline was greater than 1 mm in 51% and 44% respectively. Fat was absent in the interpterygoid fascia in 20%, in the alar fascia in 28%, in the prevertebral space in 35%, and in the retropharyngeal space in 99% of patients. Assessment of tumour extension to the paranasopharyngeal space usually relies on symmetry and fascial fat planes. As either feature may not be present in the normal person, the relation of the tumour to two lines representing two fascial planes is proposed as a complementary method for the evaluation of tumour extension.

Aldosteronoma coexisting with renal artery stenosis in secondary hypertension

A case of secondary hypertension due to an aldosteronoma coexisting with renal artery stenosis is reported. Tumor resection resulted in an immediate but short-lived clinical relief. Follow-up aortography revealed progressive arterial stenosis and infrarenal aortic occlusion. Differential renal venous renin and renal scintigraphy suggested renovascular hypertension. It is necessary to search for a second curable lesion if hypertension remains uncontrollable after surgical correction of an apparent cause.