The significance of lack of MR contrast enhancement of supratentorial brain tumors in adults: histopathological evaluation of a series

BACKGROUND

To correlate magnetic resonance imaging (MRI) findings of non-enhancement of supratentorial brain neoplasms in adults with histopathologic findings.

METHODS

Forty adult patients whose preoperative MRI studies demonstrated a non-enhancing supratentorial brain neoplasm were identified retrospectively. Biopsy material for all patients was then reviewed by a board-certified neuropathologist.

RESULTS

Histopathologic examination identified 24 (60%) low-grade gliomas: 4 (10%) low-grade astrocytomas, 10 (25%) low-grade gliomas (not further classified), 8 (20%) low-grade oligodendrogliomas, and 2 (5%) low-grade mixed oligoastrocytomas. However, 16 (40%) nonenhancing lesions were classified as anaplastic gliomas: 12 (30%) anaplastic astrocytomas, 1 (2.5%) anaplastic mixed oligoastrocytoma, 1 (2.5%) anaplastic oligodendroglioma, and 2 (5%) anaplastic infiltrating gliomas of indeterminate subtype.

CONCLUSION

Non-enhancement of supratentorial brain neoplasms in adults does not equate with low-grade malignancy. This fact should be taken into account when biopsy and treatment are being planned in patients with nonenhancing brain tumors. More aggressive and/or surgical therapy might be indicated for such lesions, particularly those in the nondominant hemisphere or nonmotor areas.

Peroxisomal lignoceroyl-CoA ligase deficiency in childhood adrenoleukodystrophy and adrenomyeloneuropathy

We previously reported that in childhood adrenoleukodystrophy (C-ALD) and adrenomyeloneuropathy (AMN), the peroxisomal beta-oxidation system for very long chain (greater than C22) fatty acids is defective. To further define the defect in these two forms of X chromosome-linked ALD, we examined the oxidation of [1-14C]lignoceric acid (n-tetracosanoic acid, C24:0) and [1-14C]lignoceroyl-CoA (substrates for the first and second steps of beta-oxidation, respectively). The oxidation rates of lignoceric acid in C-ALD and AMN were 43% and 36% of control values, respectively, whereas the oxidation rate of lignoceroyl-CoA was 109% (C-ALD) and 106% (AMN) of control values, respectively. On the other hand, the oxidation rates of palmitic acid (n-hexadecanoic acid) and palmitoyl-CoA in C-ALD and AMN were similar to the control values. These results suggest that lignoceroyl-CoA ligase activity may be impaired in C-ALD and AMN. To identify the specific enzymatic deficiency and its subcellular localization in C-ALD and AMN, we established a modified procedure for the subcellular fractionation of cultured skin fibroblasts. Determination of acyl-CoA ligase activities provided direct evidence that lignoceroyl-CoA ligase is deficient in peroxisomes while it is normal in mitochondrial and microsomes. Moreover, the normal oxidation of lignoceroyl-CoA as compared with the deficient oxidation of lignoceric acid in isolated peroxisomes also supports the conclusion that peroxisomal lignoceroyl-CoA ligase is impaired in both C-ALD and AMN. Palmitoyl-Coa ligase activity was found to be normal in peroxisomes as well as in mitochondria and microsomes. This normal peroxisomal palmitoyl-CoA ligase activity as compared with the deficient activity of lignoceroyl-CoA ligase in C-ALD and AMN suggests the presence of two separate acyl-CoA ligases for palmitic and lignoceric acids in peroxisomes. These data clearly demonstrate that the pathognomonic accumulation of very long chain fatty acids in C-ALD and AMN is due to a deficiency of peroxisomal very long chain (lignoceric acid) acyl-CoA ligase.

Lignoceroyl-CoASH ligase: enzyme defect in fatty acid beta-oxidation system in X-linked childhood adrenoleukodystrophy

We have previously reported that the peroxisomal beta-oxidation system for very long chain fatty acids is defective in X-linked childhood adrenoleukodystrophy [(1984) Proc. Natl. Acad. Sci. USA 81, 4203-4207]. In order to elucidate the specific enzyme defect, we examined the oxidation of [1-14C]lignoceric acid, [1-14C]lignoceroyl-CoA and (1-14C)-labelled alpha,beta-unsaturated lignoceroyl-CoA (substrates for the 1st, 2nd, and 3rd steps of the beta-oxidation cycle, respectively). These studies suggest that the pathognomonic accumulation of very long chain fatty acids in X-linked childhood ALD may be due to the defective activity of peroxisomal very long chain (lignoceroyl-CoA) acyl-CoA ligase.

Selective depletion of mitochondrial glutathione concentrations by (R,S)-3-hydroxy-4-pentenoate potentiates oxidative cell death

The hepatocellular glutathione content is partitioned into a cytosolic pool, which accounts for about 85% of the cellular glutathione content, and a mitochondrial pool, which accounts for about 15% of the cellular glutathione content. Previous studies indicated that the mitochondrial glutathione pool may play a critical role in cytoprotection against xenobiotic-induced cell damage. Tests of the role of mitochondrial glutathione in cytoprotection have been hampered by the lack of agents that selectively deplete the mitochondrial glutathione pool. To test the hypothesis that mitochondrial glutathione plays a critical role in protecting against cytotoxic agents, we developed a method to deplete selectively mitochondrial glutathione concentrations. (R,S)-3-Hydroxy-4-pentenoate, an analog of (R)-3-hydroxybutanoate, caused a rapid and selective depletion of mitochondrial glutathione concentrations. Incubation of (R,S)-3-hydroxy-4-pentenoate with rat liver mitochondria or with 3-hydroxybutyrate dehydrogenase in the presence of glutathione afforded a glutathione conjugate whose chromatographic properties were identical with synthetic S-(3-oxo-4-carboxybutyl)glutathione, indicating that (R,S)-3-hydroxy-4-pentenoate was oxidized to the Michael acceptor 3-oxo-4-pentenoate, which reacts with glutathione. Exposure of rat hepatocytes to (R,S)-3-hydroxy-4-pentenoate, which was not cytotoxic and did not induce mitochondrial dysfunction, potentiated the cytotoxicity of tert-butyl hydroperoxide. These results establish the critical role of mitochondrial glutathione in cytoprotection and demonstrate and (R,S)-3-hydroxy-4-pentenoate may find utility in exploring mitochondrial glutathione homeostasis.

Ten-year clinical, radiological and metal ion analysis of the Birmingham Hip Resurfacing

We present the clinical results and survivorship of consecutive 100 Birmingham Hip Resurfacings in 90 patients at a minimum follow-up of ten years. All procedures were carried out by an independent surgeon who commenced a prospective study in 1998. Patients were assessed clinically using the Western Ontario and McMaster Universities osteoarthritis index, Short-Form 36, Harris hip score and University of California, Los Angeles activity score. Radiological analysis was performed by an independent observer and blood metal ion levels concentrations were measured at ten years post-operatively in 62 patients. The median acetabular component inclination was 46.2° (34° to 59°) and anteversion 11.0° (0° to 30°). The median chromium concentration in the unilateral group was 1.74 (0.41 to 15.23) and for the bilateral group was 2.98 (1.57 to 18.01). The equivalent values for cobalt were 1.67 (0.54 to 20.4) and 1.88 (1.38 to 19.32).

In total there were eight failures giving an overall survival at ten years of 92% (95% confidence interval (CI) 86.7 to 97.3). BHR in male patients had an improved survivorship of 94.6% (95% CI 89.4 to 100) compared with females at 84.6% (95% CI 70.7 to 98.5), but this did not reach statistical significance (p = 0.119). Four of the nine BHRs with a bearing diameter of 42 mm failed.

The overall results were consistent with data produced from other centres in that the clinical outcome of large male patients was extremely encouraging, whereas the survival of the smaller joints was less satisfactory.

Outcome of complex fractures of the tibial plateau treated with a beam-loading ring fixation system

Fine-wire accepted as a minimally external fixation is invasive technique, which can provide better outcomes than traditional open methods in the management of complex fractures of the tibial plateau. Available fixators vary in their biomechanical stability, and we believe that a stable beam-loading system is essential for consistently good outcomes. We assessed, prospectively, the clinical, radiological and general health status of 20 of 21 consecutive patients with complex fractures of the tibial plateau who had been treated using a standard protocol, with percutaneous screw fixation and a neutralisation concept with a fine wire beam-loading fixator allowing early weight-bearing.

Bony union was achieved in all patients, with 85% having good or excellent results. Full weight-bearing started during the first six weeks in 60% of patients. The general health status assessment correlated well with the knee scores and reflected a satisfactory outcome.

Bicondylar tibial plateau fractures managed with the Sheffield Hybrid Fixator. Biomechanical study and operative technique

The two main challenges in the management of bicondylar tibial plateau fractures are: Firstly, the compromised skin and soft tissue envelope which invite a high rate of complications following attempted open reduction and dual plating. Secondly, poor bone quality and comminuted fracture patterns, which create difficulty in achieving stable fixation. Although dual plating is considered to be the best mechanical method of stabilizing these complex fractures, there remains concern regarding the high rate of complications associated with extensive soft tissue dissection, required for the insertion of these plates in an already compromised knee. The Sheffield Hybrid fixator (SHF) technique offers a solution to the two main problems of these difficult fractures by minimizing soft tissue dissection, since bone fragments are reduced and fixed percutaneously, and providing superior cancellous bone purchase with beam loading stabilization for comminuted fractures. Our biomechanical testing showed the SHF with four tensioned wires to be as strong as dual plating and able to provide adequate mechanical stability in the fixation of bicondylar tibial plateau fractures. This was confirmed clinically by a prospective review of the use of the SHF at our centre, for managing complex and high-energy tibial plateau fractures with a good final outcome and no cases of deep infection or septic arthritis.

What advantage is there to be gained using large modular metal-on-metal bearings in routine primary hip replacement?

The aim of this study was to investigate the possible benefit of large-head metal-on-metal bearing on a stem for primary hip replacement compared with a 28 mm diameter conventional metal-on-polyethylene bearing in a prospective randomised controlled trial. We investigated cemented stem behaviour between these two different bearings using Einzel-Bild-Röntgen-Analyse, clinical and patient reported measures (Harris hip score, Western Ontario and McMaster Universities osteoarthritis index, Short Form-36 and satisfaction) and whole blood metal ion levels at two years. A power study indicated that 50 hips were needed in each group to detect subsidence of > 5 mm at two years with a p-value of < 0.05.

Significant improvement (p < 0.001) was found in the mean clinical and patient reported outcomes at two years for both groups. Comparison of outcomes between the groups at two years showed no statistically significant difference for mean stem migration, clinical and patient reported outcomes; except overall patient satisfaction which was higher for metal-on-metal group (p = 0.05). Metal ion levels were raised above the Medicines and Healthcare products Regulatory Agency advised safety level (7 µg per litre) in 20% of the metal-on-metal group and in one patient in metal-on-polyethylene group (who had a metal-on-metal implant on the contralateral side). Two patients in the metal-on-metal group were revised, one for pseudotumour and one for peri-prosthetic fracture.

Use of large modular heads is associated with a risk of raised whole blood metal ion levels despite using a proven bearing from resurfacing. The head-neck junction or excess stem micromotion are possibly the weak links warranting further research.

Bioactivation mechanism of S-(3-oxopropyl)-N-acetyl-L-cysteine, the mercapturic acid of acrolein

S-(3-Oxopropyl)glutathione, the glutathione conjugate of acrolein, has been reported to be nephrotoxic. The objective of the present studies was to investigate the bioactivation mechanism of the analogues S-(3-oxopropyl)-N-acetyl-L-cysteine (1) and S-(3-oxopropyl)-N-acetyl-L-cysteine S-oxide (2) and to test the hypothesis that the cytotoxicity of 1 is associated with its latent potential to release acrolein in kidney cells. Mechanistic considerations indicated that sulfoxidation of sulfide 1 to form S-oxide 2 and a subsequent general-base-catalyzed beta-elimination reaction would release the cytotoxin acrolein. Hence the release of acrolein from 1 and 2 was studied in chemical systems, and their cytotoxicity was investigated in cultured LLC-PK1 cells and in isolated rat renal proximal tubular cells. Acrolein formation from S-oxide 2, but not from sulfide 1, was observed under basic conditions and with phosphate as the base. Kinetic analysis indicated that a general-base-catalyzed reaction was involved. Both S-conjugates 1 and 2 were cytotoxic in LLC-PK1 cells and in isolated rat renal proximal tubular cells, and the cytotoxicity of sulfide 1, but not of S-oxide 2, in isolated renal proximal tubular cells was reduced in presence of methimazole, an inhibitor of the flavin-containing monooxygenase. These findings indicate that the cytotoxicity of S-conjugate 1 is associated with a novel bioactivation mechanism that involves sulfoxidation followed by a general-base-catalyzed elimination of acrolein from S-oxide 2.

Stump appendicitis: a case report

Residual appendicitis is a rare event that occurs when there is incomplete resection of the organ. A recent report suggested that this may be a complication of laparoscopic surgery. Following a case of stump appendicitis in a young patient, we thoroughly reviewed the literature and found that most reported cases have occurred in open appendectomy. Awareness of the existence of this uncommon condition will help in the early diagnosis and prompt treatment of this pathology.

Pakistan Registry of Intensive CarE (PRICE): Expanding a lower middle-income, clinician-designed critical care registry in South Asia

Introduction

In resource-limited settings - with inequalities in access to and outcomes for trauma, surgical and critical care - intensive care registries are uncommon.

Aim

The Pakistan Society of Critical Care Medicine, Intensive Care Society (UK) and the Network for Improving Critical Care Systems and Training (NICST) aim to implement a clinician-led real-time national intensive care registry in Pakistan: the Pakistan Registry of Intensive CarE (PRICE).

Method

This was adapted from a successful clinician co-designed national registry in Sri Lanka; ICU information has been linked to real-time dashboards, providing clinicians and administrators individual patient and service delivery activity respectively.

Output

Commenced in August 2017, five ICU's (three administrative regions - 104 beds) were recruited and have reported over 1100 critical care admissions to PRICE.

Impact and future

PRICE is being rolled out nationally in Pakistan and will provide continuous granular healthcare information necessary to empower clinicians to drive setting-specific priorities for service improvement and research.

Flavin-containing monooxygenase-dependent stereoselective S-oxygenation and cytotoxicity of cysteine S-conjugates and mercapturates

The metabolism of cysteine S-conjugates of both cis- and trans-1,3-dichloropropene in the presence of rat kidney microsomes and purified flavin-containing monooxygenase from hog liver was investigated in vitro. Preliminary studies with isolated rat kidney cells demonstrated that cysteine S-conjugates were quite toxic to the cells in a process which was consistent with a role of the flavin-containing monooxygenase in the bioactivation of the nephrotoxins. Putative S-oxide metabolites of cysteine S-conjugates were chemically synthesized, and diastereomers were separated and identified by spectroscopic means. The metabolic products of cysteine S-conjugates were identified by comparing the chemical properties of the metabolites with authentic synthetic cysteine S-conjugate S-oxides. Surprisingly, S-conjugate S-oxygenase activity was not observed with rat kidney microsomes but was present when cysteine S-conjugates were incubated with the highly purified flavin-containing monooxygenase from hog liver. The kinetic parameters indicated that considerable S-oxygenase stereoselectivity and structural selectivity was observed: cis cysteine S-conjugates were preferred substrates and N-acetylation of cysteine S-conjugates decreased substrate activity. S-Oxygenation was considerably diastereoselective and diastereoselectivity was much greater for cysteine S-conjugates with higher Vmax values. Cysteine S-conjugate S-oxides were not indefinitely stable, and under certain conditions, the S-oxides underwent a [2,3]-sigmatropic rearrangement to acrolein. Formation of acrolein or other electrophilic products from S-(chloropropenyl)cysteine conjugate S-oxides may contribute to the renal effects observed for S-(chloropropenyl)cysteine conjugates.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioactivation of [13C]dichloromethane in mouse, rat, and human liver cytosol: 13C nuclear magnetic resonance spectroscopic studies

Dichloromethane is tumorigenic in lungs and liver of B6C3F1 mice, but is not tumorigenic in rats or hamsters, and its toxicity is associated with glutathione-dependent bioactivation. The objective of the present studies was to investigate the glutathione-dependent bioactivation of [13C]dichloromethane in mouse, rat, and human liver cytosol and the fate of dichloromethane-derived reactive intermediates with 13C NMR. [13C]Formaldehyde hydrate, [13C]S-(hydroxymethyl)glutathione, and [13C]methanol were identified as metabolites of [13C]dichloromethane. [13C]S-(Chloromethyl)glutathione, a putative intermediate in the glutathione-dependent bioactivation of dichloromethane, or derived adducts were not observed. Moreover, no evidence for the formation of S,S'-methylenebis[glutathione] by reaction of glutathione and formaldehyde under physiological conditions was obtained, although methanol was observed as a product. S,S'-Methylenebis[glutathione] was, however, formed by reaction of glutathione and formaldehyde at pH 1. S-(Chloromethyl)-N-acetyl-L-cysteine methyl ester, a surrogate for S-(chloromethyl)glutathione, was prone to hydrolysis. These results corroborate the finding that formaldehyde is a reactive intermediate formed during the glutathione-dependent bioactivation of dichloromethane that may be involved in the observed tumorigenicity of dichloromethane in susceptible species. The results also indicate that S-(chloromethyl)glutathione is an intermediate in the glutathione-dependent bioactivation of dichloromethane and may also play a role in its mutagenicity and carcinogenicity.

Enzymatic reaction of beta-N-methylaminoalanine with L-amino acid oxidase

The reaction of beta-N-methylaminoalanine (BMAA) with L-amino acid oxidase (L-AAO) in the presence of catalase yields ammonia and beta-N-methylaminopyruvate, which was trapped as its 2,4-dinitrophenylhydrazone, as products. Incubation of BMAA with L-AAO in the presence of semicarbazide led to the formation of a semicarbazone, indicating intermediate iminium ion formation; when potassium cyanide (5 mM) was added, semicarbazone formation was blocked. The formation of beta-N-methylaminopyruvate was decreased by omission of catalase and was reduced in the presence of hydrogen peroxide (100 mM). These results indicate that BMAA is converted by L-AAO to the corresponding alpha-imino acid, which undergoes hydrolysis to beta-N-methylaminopyruvate. The alpha-keto acid is readily oxidized to N-methylglycine by hydrogen peroxide.

Fourier-transform ion cyclotron resonance mass spectrometric evidence for the formation of alpha-chloroenethiolates and thioketenes from chloroalkene-derived, cytotoxic 4-thiaalkanoates

The cytotoxicity of chloroalkene-derived cysteine S-conjugates is thought to be associated with the formation of alpha-chloroenethiolates and thioketenes as reactive intermediates. Recent studies indicate that the formation of 1,2-dichloroethenethiolate, which may give rise to chlorothioketene, is a key step in the bioactivation of 5,6-dichloro-4-thia-5-hexenoic acid (Fitzsimmons et al. (1995) Biochemistry 34, 4276-4286). We report here the use of Fourier-transform ion cyclotron resonance mass spectrometry to provide the first direct evidence for the formation of alpha-chloroenethiolate and thioketene species from a cytotoxic 4-thiaalkanoate. The bioactivation of 5,6-dichloro-4-thia-5-hexenoic acid involves conversion to the corresponding CoA thioester 5,6-dichloro-4-thia-5-hexenoyl-CoA and subsequent processing by the fatty acid beta-oxidation pathway. It has been proposed that the bioactivation of 5,6-dichloro-4-thia-5-hexenoyl-CoA involves loss of 1,2-dichloroethenethiolate, followed by loss of chloride to form chlorothioketene. 1,2-Dichloroethenethiolate and related alpha-chloroalkenethiolates have not been observed directly in aqueous solution. Fourier-transform ion cyclotron resonance mass spectrometric experiments show that S-propyl 5,6-dichloro-4-thia-5-hexenethioate reacts in the gas phase with base (hydroxide ion) to release 1,2-dichloroethenethiolate, which is observed directly in the mass spectrum of the products of the gas-phase reaction. Furthermore, the elimination of chloride from 1,2-dichloroethenethiolate on collision-induced decomposition is facile and provides evidence for chlorothioketene formation. Preliminary evidence for the formation of 1,2-dichloroethenethiolate and chlorothioketene from S-(1,2-dichlorovinyl)-N-acetyl-L-cysteine methyl ester was also obtained. These observations support the intermediacy of alpha-chloroenethiolates and chlorothioketenes in the bioactivation of cytotoxic, chloroalkene-derived 4-thiaalkanoates and cysteine S-conjugates and demonstrate the utility of Fourier-transform ion cyclotron mass spectrometry in studying the formation of reactive intermediates.

Enantioselective depletion of mitochondrial glutathione concentrations by (S)- and (R)-3-hydroxy-4-pentenoate

(R,S)-3-Hydroxy-4-pentenoate rapidly and selectively depletes the mitochondrial glutathione pool in rat hepatocytes, but shows little cytotoxicity and does not induce mitochondrial dysfunction [Shan, X., et al. (1993) Chem. Res. Toxicol. 6, 75-81]. The objective of the present studies was to investigate the 3-hydroxybutanoate dehydrogenase-dependent oxidation of (R)- and (S)-3-hydroxy-4-pentenoate and the enantioselectivity of 3-hydroxy-4-pentenoate-induced depletion of mitochondrial glutathione concentrations in isolated rat liver mitochondria and hepatocytes. (S)-3-Hydroxy-4-pentenoate, but not (R)-3-hydroxy-4-pentenoate, was a substrate for 3-hydroxybutanoate dehydrogenase. Incubation of rat liver mitochondria or hepatocytes with (S)-3-hydroxy-4-pentenoate resulted in a time- and concentration-dependent depletion of mitochondrial glutathione concentrations, whereas (R)-3-hydroxy-4-pentenoate produced little depletion. These results show that (S)-3-hydroxy-4-pentenoate is a substrate for 3-hydroxy-butanoate dehydrogenase and is converted to the Michael acceptor 3-oxo-4-pentenoate, which reacts with glutathione and thereby depletes the mitochondrial glutathione pool. (S)-3-Hydroxy-4-pentenoate may find use in the study of mitochondrial glutathione homeostasis and the role of mitochondrial glutathione in cellular protection.

Expression of the vascular endothelial growth factor receptors 1 and 2 in acute myeloid leukemia: incidence and feasibility of immunohistochemical staining

Vascular endothelial growth factor (VEGF) and its receptor tyrosine kinases, VEGFR-1 and VEGFR-2, are important therapeutic targets for various cancers including AML. Paraffin-embedded bone marrow samples (PE-BM) are, in most cases, the only tissue accessible to perform retrospective analyses of novel targets such as VEGF and/or its receptors. As a result, it limits our options to immunohistochemistry (IHS), or more expensive and less practical techniques such as enzyme-linked immunosorbent assay (ELISA) or fluorescence in situ hybridization (FISH). We analyzed the feasibility of IHS to measure VEGFR-1 and VEGFR-2 expression in 28 AML samples using monoclonal antibodies (moAbs) against Flt-1 (VEGFR-1) and KDR/Flk-1 (VEGFR-2). Medical records were reviewed for relevant clinical information. Expression of VEGFR-1 (+) and VEGFR-2 (+) were seen in 25% (7/28) and 43% (12/28) respectively. Forty-six percent (13/28) were dual-negatives for VEGFR-1 and VEGFR-2; 14% (4/28) were dual-positives for VEGFR-1 and VEGFR-2. An inferior survival was observed in patients whose myeloblasts express either VEGFR-1 (+) or VEGFR-2 (+), or both. Determination of expression of VEGF receptors (1 and 2) by IHS in PE-BM tissue is feasible. Prospective comparison of IHC to flow cytometry or other molecular techniques, and assessment of the prognostic significance of VEGF receptors in AML patients is warranted.

Affinity ligands and related agents for brain muscarinic and nicotinic cholinergic receptors

This study describes the chemical synthesis and receptor binding characteristics of various affinity ligands and related ligands for brain muscarinic and nicotinic cholinergic receptors, including the 4-bromoacetamidobenzoic acid esters of dimethylaminoethanol (DMBAB) and choline (BABC) and 4-iodoacetamidobenzoylcholine (IABC). The reversible binding of [3H]3-quinuclidinylbenzilate ([3H]QNB) to calf brain membranes was inhibited in a concentration-dependent and saturable manner by DMBAB, BABC, and IABC with Ki values of 8 x 10(-7), 3 x 10(-7) and 8 x 10(-7) M, respectively; the Ki values for inhibition of reversible binding of the nicotinic ligand, [3H]methylcarbamylcholine ([3H]-MCC), were 1 x 10(-6), 6 x 10(-8), and 1 x 10(-6) M, respectively. The Ki values for irreversible inhibition of [3H]QNB binding were 8 x 10(-7), 1 x 10(-7), and 2 x 10(-7) M for DMBAB, BABC, and IABC, respectively, and for [3H]MCC binding, 8 x 10(-5), 1 x 10(-5), and 2 x 10(-5) M, respectively. Although DMBAB was found to inhibit the QNB-induced hyperactivity in mice, it did not antagonize the toxic or other pharmacologic effects of oxotremorine. Structure-activity studies with various non-affinity analogues of the 4-aminobenzoate ester of dimethylaminoethanol and choline revealed that removal of the NH2 moiety from the phenyl group increased affinity for the muscarinic but not the nicotinic cholinergic site, and quaternization of the ester side chain greatly increased affinity for the muscarinic site. Dimethylation of NH2 in 4-aminobenzoylcholine decreased the affinity for both cholinergic sites. Replacement of NH2 by NO2 increased affinity for the muscarinic but not the nicotinic site, whereas quaternization of the 4-nitrobenzoyl ester markedly increased affinity for the nicotinic site while diminishing affinity for the muscarinic site. The findings indicate that DMBAB and its analogues are useful affinity ligands for examining the biochemical and functional characteristics of brain cholinergic receptors, particularly the muscarinic which has an affinity near the nanomolar concentration range.

Validation of acute physiologic and chronic health evaluation II scoring system software developed at The Aga Khan University, Pakistan

Objective:

To assess the predictive performance of Acute Physiologic and Chronic Health Evaluation II (APACHE II) software available on the hospital intranet and analyze interrater reliability of calculating the APACHE II score by the gold standard manual method or automatically using the software.

Materials and Methods:

An expert scorer not involved in the data collection had calculated APACHE II score of 213 patients admitted to surgical Intensive Care Unit using the gold standard manual method for a previous study performed in the department. The same data were entered into the computer software available on the hospital intranet (http://intranet/apacheii) to recalculate the APACHE II score automatically along with the predicted mortality. Receiver operating characteristic curve (ROC), Hosmer-Lemeshow goodness-of-fit statistical test and Pearson's correlation coefficient was computed.

Results:

The 213 patients had an average APACHE II score of 17.20 ± 8.24, the overall mortality rate was 32.8% and standardized mortality ratio was 1.00. The area under the ROC curve of 0.827 was significantly >0.5 (P < 0.01) and had confidence interval of 0.77-0.88. The goodness-of-fit test showed a good calibration (H = 5.46, P = 0.71). Interrater reliability using Pearson's product moment correlations demonstrated a strong positive relationship between the computer and the manual expert scorer (r = 0.98, P = 0.0005).

Conclusion:

APACHE II software available on the hospital's intranet has satisfactory calibration and discrimination and interrater reliability is good when compared with the gold standard manual method.

4-Bromoacetamidoprocaine: an affinity ligand for brain muscarinic and nicotinic cholinergic receptors

This study describes the synthesis, receptor binding characteristics, and some behavioral effects of p-bromoacetamidoprocaine (BAP), a new affinity ligand for brain muscarinic and nicotinic cholinergic receptors. The reversible binding of [3H]QNB to rat brain membranes was inhibited in a concentration dependent and saturable manner by both procaine and BAP, with Ki values of 4 x 10(-6) and 3 x 10(-7) M, respectively, and complete inhibition at 1 x 10(-5) M. Both procaine and BAP, although at much concentrations, inhibited the binding of [3H]methylcarbamylcholine in a concentration dependent manner, with Ki values of 5 x 10(-5) and 1 x 10(-5) M, respectively, and complete inhibition for both at 1 x 10(-3) M. Plots of the % irreversible inhibition of [3H]QNB, [3H]nicotine, and [3H]MCC vs [BAP] yielded Ki values of 7 x 10(-8), 1 x 10(-4), and 6 x 10(-5) M, respectively. In behavioral studies BAP was able to antagonize the QNB-induced hyperactivity in mice; however, BAP did not appear to alter nicotine-induced seizure activity or other behavioral effects in mice. A plot of the time course of inhibition by BAP for [3H]QNB binding revealed that the inhibition was almost complete within 10 min exposure at 37 degrees. The findings indicate that BAP is a useful affinity ligand for examining the biochemical and functional characteristics of brain cholinergic receptors, particularly the muscarinic which has an affinity near the nM concentration range.