Tolosa-Hunt syndrome: MRI appearances

A review of MRI findings in seven patients with Tolosa-Hunt syndrome was carried out. Seven patients presented with unilateral painful ophthalmoplegia. Magnetic resonance imaging studies were carried out to evaluate the cavernous sinuses and orbits. Coronal fast spin-echo T2-weighted images and fat-saturated T1-weighted coronal and transverse images with and without contrast enhancement were obtained for the cavernous sinuses and orbits. All patients showed focal-enhancing masses expanding the ipsilateral cavernous sinus. In one patient the mass was extending to the orbital apex and intraorbitally. All patients recovered on corticosteroid therapy and resolution of the masses was documented on follow-up MRI studies in five patients. One patient had a relapse of symptoms after discontinuing therapy. Magnetic resonance imaging studies of the cavernous sinus and orbital apex show high sensitivity for the detection and follow up of inflammatory mass lesions in Tolosa-Hunt syndrome. Magnetic resonance imaging should be the initial screening study in these patients.

Artificial neural network-based glaucoma diagnosis using retinal nerve fiber layer analysis

PURPOSE

To develop, train, and test an artificial neural network (ANN) for differentiating among normal subjects, primary open angle glaucoma (POAG) suspects, and persons with POAG in Asian-Indian eyes using inputs from clinical parameters, optical coherence tomography (OCT), visual fields, and GDx nerve fiber analyzer.

METHODS

One hundred eyes were classified using optic disc examination and perimetry into normal (n=35), POAG suspects (n=30), and POAG (n=35). EasyNN-plus simulator was used to develop an ANN model with inputs including age, sex, myopia, intraocular pressure (IOP), optic nerve head, and retinal nerve fiber layer (RNFL) parameters on OCT, Octopus 30-2 full threshold visual field, and GDx parameters.

RESULTS

With two outputs (POAG or normal), specificity was 80% and sensitivity was 93.3%. Ninety percent of POAG suspects were labeled as abnormal in this analysis. ANN assigned the highest importance to Smax/Imax RNFL on OCT followed by cup-area (OCT) and other RNFL parameters (OCT) for two outputs. With three outputs (normal, POAG, and POAG suspect), ANN gave an overall classification rate of 65%, specificity of 60%, and sensitivity of 71.4% with a target error rate of the training set at 1%. The parameters for three outputs, in decreasing order of relative importance, were Savg, vertical cup-disc ratio, cup-volume, and cup-area on OCT.

CONCLUSIONS

An ANN taking varied diagnostic imaging inputs was able to separate POAG eyes from normal subjects and POAG suspects. The network had reasonable sensitivity with three outputs; however, it had a tendency to mislabel POAG suspects as POAG.

Exenatide and acute pancreatitis

For a female, type 2 diabetic patient, with 4 years duration of diabetes, Exenatide (Byetta) was prescribed as glycaemic control was not satisfactory along with Glimepiride and Metformin. She had gastrointestinal disturbances, since the first day of the injection. From the eighth day she developed signs of acute pancreatitis which was confirmed with CT-Scan and biochemical investigations. Byetta was withdrawn, the patient was treated for acute pancreatitis and the symptoms subsided.

Efficacy, safety and patterns of response and recurrence in patients with recurrent high-grade gliomas treated with bevacizumab plus irinotecan

Our objective is to assess treatment efficacy, safety and pattern of response and recurrence in patients with recurrent high-grade glioma treated with bevacizumab and irinotecan. We reviewed retrospectively 51 patients with recurrent high-grade glioma treated with this combination at the Henry Ford Hermelin Brain Tumor Center from 11/15/2005 to 04/01/2008. The 6-month progression-free survival (PFS) for anaplastic gliomas (AGs) was 78.6 and 63.7% for glioblastoma. The median PFS was 13.4 months for AG and 7.6 months for those with glioblastoma. The overall survival rate (OS) at 6 months was 85.7% for AG and 78.0% for glioblastoma. The 12-month OS was 77.9% for AG and 42.6% for glioblastoma. The median OS time for AGs was not reached and was 11.5 months for those with glioblastoma. Thirty-six out of 51 (70.59%) patients demonstrated partial (32/51) or complete (4/51) radiographic response to treatment and 8/51 (15.69%) remained stable. Of the 38 who demonstrated progression on post-gadolinium studies, 23 showed distant progression with or without local recurrence. Seven patients showed progression on FLAIR without concordant findings on post-Gd sequences. Six patients (11.76%) discontinued treatment due to a treatment-emergent adverse event, including one with end-stage renal failure and another with gastric perforation. No symptomatic intracranial hemorrhages were reported. Patients with recurrent high-grade glioma treated with bevacizumab plus irinotecan demonstrate an excellent radiographic response rate and improved clinical outcome when compared to historical data. The high rate of distant tumor progression suggests that tumors may adapt to inhibition of angiogenesis by increased infiltration and vascular co-option.

Structure of Desulfitobacterium hafniense PylSc, a pyrrolysyl-tRNA synthetase

Pyrrolysine, the 22nd genetically-encoded amino acid, is charged onto its specific tRNA by PylS, a pyrrolysyl-tRNA synthetase. While PylS is found as a single protein in certain archaeal methanogens, in the gram-positive bacterium Desulfitobacterium hafniense, PylS is divided into two separate proteins, PylSn and PylSc, corresponding to the N-terminal and C-terminal domains of the single PylS protein found in methanogens. Previous crystallographic studies have provided the structure of a truncated C-terminal portion of the archaeal Methanosarcina mazei PylS associated with catalysis. Here, we report the apo 2.1A resolution structure of the intact D. hafniense PylSc protein and compare it to structures of the C-terminal truncated PylS from methanogenic species. In PylSc, the hydrophobic pocket binding the ring of pyrrolysine is more constrained than in the archaeal enzyme; other structural differences are also apparent.

Crystallization and structure determination of the core-binding domain of bacteriophage lambda integrase

Bacteriophage lambda integrase catalyzes site-specific DNA recombination. A helical bundle domain in the enzyme, called the core-binding domain (Int(CB)), promotes the catalysis of an intermediate DNA-cleavage reaction that is critical for recombination and is not well folded in solution in the absence of DNA. To gain structural insights into the mechanism behind the accessory role of this domain in catalysis, an attempt was made to crystallize an Int(CB)-DNA complex, but crystals of free Int(CB) were fortuitously obtained. The three-dimensional structure of DNA-free Int(CB) was solved at 2.0 A resolution by molecular replacement using as the search model the previously available DNA-bound 2.8 A structure of the Int(CB) domain in a larger construct of lambda integrase. The crystal structure of DNA-free Int(CB) resembles the DNA-bound structure of Int(CB), but exhibits subtle differences in the DNA-binding face and lacks electron density for ten residues in the C-terminus that form a portion of a linker connecting Int(CB) to the C-terminal catalytic domain of the enzyme. Thus, this work reveals the domain in the absence of DNA and allows comparison with the DNA-bound form of this catalytically activating domain.

A case of aspartate aminotransferase macroenzyme

Aspartate aminotransferase (AST) macroenzyme can result in elevated AST activity in patients with no disease. This case report describes a six-year-old boy who presented to his family doctor with a history of chronic constipation and lower back pain. Routine blood tests showed normal creatine kinase activity (CK), normal alanine aminotransferase activity (ALT) but raised AST. The patient was referred to a hospital paediatrician for further investigation of the abnormal AST and back pain. The raised AST was confirmed as the only biochemical abnormality. Further investigation with polyethylene glycol, followed by measurement of AST in the supernatant, showed undetectable enzyme activity. The sample was sent to a specialist laboratory where it was analysed by Sephacryl S300 gel filtration. This procedure confirmed the presence of a high molecular mass form of AST. AST macroenzyme should be considered as a cause of isolated AST increase, which may avoid further costly investigations.

Quantitative estimation of permeability surface-area product in astroglial brain tumors using perfusion CT and correlation with histopathologic grade

BACKGROUND AND PURPOSE

Glioma angiogenesis and its different hemodynamic features, which can be evaluated by using perfusion CT (PCT) imaging of the brain, have been correlated with the grade and the aggressiveness of gliomas. Our hypothesis was that quantitative estimation of permeability surface area product (PS), cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) in astroglial brain tumors by using PCT will correlate with glioma grade. High-grade gliomas will show higher PS and CBV as compared with low-grade gliomas.

MATERIALS AND METHODS

PCT was performed in 32 patients with previously untreated astroglial tumors (24 high-grade gliomas and 8 low-grade gliomas) by using a total acquisition time of 170 seconds. World Health Organization (WHO) glioma grades were compared with PCT parameter absolute values by using Student or nonparametric Wilcoxon 2-sample tests. Receiver operating characteristic (ROC) analyses were also done for each of the parameters.

RESULTS

The differences in PS, CBV, and CBF between the low- and high-grade tumor groups were statistically significant, with the low-grade group showing lower mean values than the high-grade group. ROC analyses showed that both CBV (C-statistic 0.930) and PS (C-statistic 0.927) were very similar to each other in differentiating low- and high-grade gliomas and had higher predictability compared with CBF and MTT. Within the high-grade group, differentiation of WHO grade III and IV gliomas was also possible by using PCT parameters, and PS showed the highest C-statistic value (0.926) for the ROC analyses in this regard.

CONCLUSIONS

Both PS and CBV showed strong association with glioma grading, high-grade gliomas showing higher PS and CBV as compared with low-grade gliomas. Perfusion parameters, especially PS, can also be used to differentiate WHO grade III from grade IV in the high-grade tumor group.

Functional specificity of a Hox protein mediated by the recognition of minor groove structure

The recognition of specific DNA-binding sites by transcription factors is a critical yet poorly understood step in the control of gene expression. Members of the Hox family of transcription factors bind DNA by making nearly identical major groove contacts via the recognition helices of their homeodomains. In vivo specificity, however, often depends on extended and unstructured regions that link Hox homeodomains to a DNA-bound cofactor, Extradenticle (Exd). Using a combination of structure determination, computational analysis, and in vitro and in vivo assays, we show that Hox proteins recognize specific Hox-Exd binding sites via residues located in these extended regions that insert into the minor groove but only when presented with the correct DNA sequence. Our results suggest that these residues, which are conserved in a paralog-specific manner, confer specificity by recognizing a sequence-dependent DNA structure instead of directly reading a specific DNA sequence.

Outcome of sixty four cases of ethylene dibromide ingestion treated in tertiary care hospital

BACKGROUND AND AIMS

In view of high incidence and mortality due to ethylene dibromide poisoning, a prospective study was planned to assess demographic, toxicological, clinical profile and outcome.

MATERIAL AND METHODS

Prospectively collected data of sixty four patients with ethylene dibromide poisoning were reviewed. All the patients were from Gwalior and neighbouring districts.

RESULTS

Majority were males in the age group 21-30 years. Out of sixty-four cases 26 patients (40.6%) survived and 38 patients (59.4%) expired. Nausea vomiting and pain abdomen were most common symptoms at presentation. Diarrhoea, drowsiness, palpitations and oliguria were other features. Pulse rate was normal (< 100) in 22 (84.6%) survived patients whereas it was > 100 in 24 (63.1%) of expired patients at the time of admission (p value = 0.0004199). Half ampoule (1.5ml.) of ethylene dibromide was sufficient as fatal dose. Mortality was 20% and 46.15% with half and one ampoule respectively. Best outcome was when the patient presented to the hospital within six hours. Death occurred anywhere between twelve hours and five days. Gastrointestinal toxicity was predominant at presentation. Nausea, vomiting and abdominal pain was present in all the patients. Nephrotoxicity 32 (50%), hepatotoxicity 28 (43.8%), cardiotoxicity 28 (43.8%), central nervous system 8 (12.5%) toxicity and hypoglycemia 24 (37.5%) were also observed.

CONCLUSION

Ethylene dibromide is highly toxic. Patients who consumed half to one ampoule usually survived with supportive care provided they presented to the hospital within six hours. Pulse rate more than 100 at presentation was a poor prognostic factor. Patients with normal pulse and blood pressure at admission had better prognosis.

Role of perfusion CT in glioma grading and comparison with conventional MR imaging features

BACKGROUND AND PURPOSE

Perfusion imaging using CT can provide additional information about tumor vascularity and angiogenesis for characterizing gliomas. The purpose of our study was to demonstrate the usefulness of various perfusion CT (PCT) parameters in assessing the grade of treatment-naïve gliomas and also to compare it with conventional MR imaging features.

MATERIALS AND METHODS

PCT was performed in 19 patients with glioma (14 high-grade gliomas and 5 low-grade gliomas). Normalized ratios of the PCT parameters (normalized cerebral blood volume [nCBV], normalized cerebral blood flow [nCBF], normalized mean transit time [nMTT]) were used for final analysis. Conventional MR imaging features of these tumors were assessed separately and compared with PCT parameters. Low- and high-grade gliomas were compared by using the nonparametric Wilcoxon 2-sample tests.

RESULTS

Mean nCBV in the high- and low-grade gliomas was 3.06 +/- 1.35 and 1.44 +/- 0.42, respectively, with a statistically significant difference between the 2 groups (P = .005). Mean nCBF for the high- and low-grade gliomas was 3.03 +/- 2.16 and 1.16 +/- 0.36, respectively, with a statistically significant difference between the 2 groups (P = .045). Cut points of >1.92 for nCBV (85.7% sensitivity and 100% specificity), >1.48 for nCBF (71.4% sensitivity and 100% specificity), and <1.94 for nMTT (92.9% sensitivity and 40% specificity) were found to identify the high-grade gliomas. nCBV was the single best parameter; however, using either nCBV of >1.92 or nCBF of >1.48 improved the sensitivity and specificity to 92.9% and 100%, respectively. The sensitivity and specificity for diagnosing a high-grade glioma with conventional MR imaging were 85.7% and 60%, respectively.

CONCLUSIONS

PCT can be used for preoperative grading of gliomas and can provide valuable complementary information about tumor hemodynamics, not available with conventional imaging techniques. nCBV was the single best parameter correlating with glioma grades, though using nCBF when nCBV was <1.92 improved the sensitivity. An nCBV threshold of >1.92 was found to identify the high-grade gliomas.

Acute bone crises in sickle cell disease: the T1 fat-saturated sequence in differentiation of acute bone infarcts from acute osteomyelitis

AIM

To prove the hypothesis that acute bone infarcts in sickle cell disease are caused by sequestration of red blood cells (RBCs) in bone marrow, and to evaluate the unenhanced T1 fat-saturated (fs) sequence in the differentiation of acute bone infarction from acute osteomyelitis in patients with sickle-cell disease.

MATERIALS AND METHODS

Two studies were undertaken: an experimental study using in-vitro packed red blood cells and normal volunteers, and a retrospective clinical study of 86 magnetic resonance imaging (MRI) studies. For the experimental study containers of packed RBCs were placed between the knees of four healthy volunteers with a saline bag under the containers as an additional control, and were scanned with the pre-contrast T1-fs sequence. Signal intensity (SI) ratios were obtained for packed RBCs:skeletal muscle and packed RBCs:saline. For the clinical study, the SIs of normal bone marrow, packed RBCs, bone and/or soft-tissue lesions, and normal skeletal muscle of 74 patients (86 MRI studies) were measured using unenhanced, T1 fat-saturated MRI. The ratios of the above SIs to normal skeletal muscle were calculated and subjected to statistical analysis.

RESULTS

Fifty-one of 86 MRI studies were included in the final analysis. The ratios of SIs for normal bone marrow, packed red cells, bone infarction, acute osteomyelitis, and soft-tissue lesions associated with bone infarct, compared with normal skeletal muscle were (mean+/-SD) 0.9+/-0.2, 2.1+/-0.7, 1.7+/-0.5, 1.0+/-0.3, and 2.2+/-0.7, respectively. The difference in the ratio of SIs of bone infarcts and osteomyelitis was significant (p=0.003). The final diagnoses were bone infarction (n=50), acute osteomyelitis (n=1), and co-existent bone infarction and osteomyelitis (n=2). Seven patients who had suspected osteomyelitis underwent image-guided aspiration.

CONCLUSION

Acute bone infarcts in sickle cell disease are caused by sequestration of red blood cells in the bone marrow. The unenhanced, T1-fat-saturated sequence alone is diagnostic for acute bone infarcts. Contrast enhancement aids in the diagnosis of acute osteomyelitis. MRI can thus help in early diagnosis, specific treatment, and preventing empirical antibiotic therapy.