Characterization of chest masses by FDG positron emission tomography

Radiographic imaging techniques have proved to be of limited value in characterizing chest masses. Likewise, scintigraphic techniques with tumor-seeking single photon emitting agents have shown marginal practical benefit. In contrast, high resolution PET with [F-18]-2-fluoro-2-D-deoxyglucose (FDG) offers a unique opportunity to distinguish benign from malignant processes by determining metabolic characteristics. PET scan results, including graphical analysis of tumor transfer constants (Patlak plot) in 21 patients with primary lung cancer, were compared to clinical outcome (histologic proof or clinical follow-up of longer than 1 year) in 54 patients who had chest masses identified by CT and/or plain film. The patients were categorized into three groups. The first group (N = 23) had primary, unknown, lung masses. Differentiation of benign from malignant tumors by PET had a sensitivity of 100% and a specificity of 67%. The second group (N = 13) had proven lung carcinoma or lymphoma and post-therapy PET scanning for recurrent tumor. In this setting, PET had a sensitivity of 83% and a specificity of 80%. The third group (N = 18) had extrathoracic malignancies and suspected pulmonary metastases. Metastatic lesions were identified with a sensitivity of 87% and specificity of 83%. Glucose uptake by normal tissue is variable and inflammatory/infectious processes can have high FDG uptake and overlap with the glucose uptake of malignant tissue. FDG PET is useful in characterizing chest tumors based on the level of their metabolic activity. Malignant tissue has a high glucose uptake. Elevated FDG uptake by an active inflammatory process may produce overlapping results.(ABSTRACT TRUNCATED AT 250 WORDS)

Colovesical fistula complicating colonic diverticulosis

Two cases of colovesical fistulae secondary to colonic diverticulosis are reported. Urinary symptoms were the prominent presenting features. Barium enema was helpful in documenting the fistulae, which cystoscopically was not localised. Definitive treatment included resection of the fistula and the diseased segment of the intestine. Both patients are well on follow-up. Diverticulosis coli should be considered in the differential diagnosis of colovesical fistulae even in tropical countries.

Stereoselective metabolism of dibenz[a,h]acridine to bay-region diol epoxides by rat liver microsomes

The carcinogen dibenz[a,h]acridine (DB[a,h]ACR is metabolized predominantly to trans-3,4-dihydroxy-3,4-dihydro-dibenz[a,h]acridine (DB[a,h]ACR-3,4-diol) and the proximate carcinogen trans-10,11-dihydroxy-10,11-dihydrodibenz[a,h]acridine (DB[a,h]ACR-10,11-diol) [Steward et al. (1987) Carcinogenesis, 8, 1043-1050]. In the present investigation, the stereoselectivity of rat liver enzymes in metabolism of DB[a,h]ACR to its 3,4-diol and 10,11-diol and of DB[a,h]ACR-10,11-diol enantiomers to their bay-region diol epoxides has been examined with liver microsomes from control and 3-methylcholanthrene-treated rats. Both microsomal preparations produced the major metabolites DB[a,h]ACR-3,4-diol and DB[a,h]ACR-10,11-diol containing predominantly R,R-enantiomers with 38-54% optical purity. Metabolism of (-)-(10R,11R)- and (+)-(10S,11S)-enantiomers of DB[a,h]ACR-10,11-diol by liver microsomes from control rats produced predominantly bay-region diol epoxides (46-59% of total metabolites), whereas very little bay-region diol epoxides (14-17% of total metabolites) were produced by liver microsomes from 3-methylcholanthrene-treated rats. The bay-region diol epoxides produced in these studies consisted of predominantly DB[a,h]ACR-10,11-trans-diol epoxide diastereomer in which the benzylic hydroxyl group and epoxide oxygen are trans. However, (-)-DB[a,h]ACR-10R,11R-diol, a major metabolite of DB[a,h]ACR, was metabolized by liver microsomes from 3-methylcholanthrene-treated rats to (+)-[8R,9S,10S,11R]-DB[a,h]ACR-10,11-trans-diol epoxide, a diastereomer which displayed high mutagenic activity in V79 cells, in an amount which was 6.5-fold greater than that of the corresponding cis-diol epoxide diastereomer. The relative amounts of trans-diol epoxide versus cis-diol epoxide in the mixture of bay-region diol epoxides produced from DB[a,h]ACR-10R,11R-diol and DB[a,h]ACR-10S,11R-diol with liver microsomes from control rats and from DB[a,h]ACR-10S,11S-diol with liver microsomes from 3-methylcholanthrene-treated rats were 1.7, 2.1 and 2.3 respectively.

Sensitive high-performance liquid chromatographic method for the determination of methyl N-[5-[[4-(2-pyridinyl)-1-piperazinyl]carbonyl]-1H-benzimidazol-2-yl d carbamate in rat blood

A sensitive high-performance liquid chromatographic assay has been developed and validated for the determination of methyl N-[5-[[4-(2-pyridinyl)-1-piperazinyl]carbonyl]-1H-benzimidazol-2-y l d carbamate (CDRI compound 81/470) in normal rat blood. The method described herein is simple, with improved selectivity and sensitivity over a previously reported HPLC method. The limit of quantitation is 10 ng/ml (method 1) and 2.5 ng/ml (method 2) in blood, as compared with 40 ng/ml for the previous method. The standard curve in blood is linear over the concentration range 10-1000 ng/ml in method 1 and 2.5-1000 ng/ml in method 2 and the extraction recovery is higher than 80% for both methods.

Detection of numerical chromosomal aberrations in paraffin-embedded malignant pleural mesothelioma by non-isotopic in situ hybridization

An in situ hybridization (ISH) study on paraffin sections of 13 malignant mesotheliomas was performed to detect numerical chromosomal aberrations with biotin-labelled DNA probes specific for the centromeric regions of chromosomes 1, 3, 6, 7, 11, and 17. All chromosomes contributed to numerical changes, which can be summarized as follows: first, a monosomy for chromosome 6 was found in one case; second, in five cases a trisomy for at least one chromosome was detected; and third, in seven cases a pentasomy or a higher polysomy was found for at least one chromosome. Although these data have to be confirmed on a larger group of patients, survival analysis of this group showed no significant difference between the first and second groups taken together and the third group. In this study no specific numerical chromosomal aberrations were identified. Nevertheless, numerical gains appear to be more frequent than has previously been shown by karyotype analysis.

Mutational analysis demonstrates different functional roles for the two ATP-binding sites in ClpAP protease from Escherichia coli

ClpA, the regulatory subunit of Clp protease from Escherichia coli, has two ATP-binding sites in non-homologous regions of the protein, referred to as domain I and domain II. We have mutated the invariant lysine in the ATP-binding sites of domain I and domain II and studied the enzymatic properties of the purified mutant ClpA proteins. The domain I mutant, ClpA-K220Q, was unable to form a hexamer in the presence of nucleotide, but the comparable domain II mutant, ClpA-K501Q, associated into a hexamer in the presence of ATP, indicating that nucleotide binding to domain I favors a conformation required to stabilize the quaternary structure of ClpA. ClpA-K220Q was defective in ATPase activity and in the ability to activate protein and peptide degradation by ClpP, but the defects could be partially overcome by formation of hybrid hexamers with wild-type ClpA. Another domain I mutant, ClpA-K220R, readily formed hexamers in the presence of ATP and retained > or = 60% of the wild-type ATPase activity and ability to activate ClpP. These results indicate that hexamer formation is a prerequisite for expression of enzymatic activity. Domain II mutants ClpA-K501Q and ClpA-K501R had very low ATPase activity (< 10% of wild-type) and a severe defect in activation of protein degradation, which requires ATP hydrolysis. Domain II mutants were able to activate ClpP to degrade a peptide whose degradation required nucleotide binding but not hydrolysis. Nucleotide binding to domain II of ClpA is important to form a productive complex with ClpP, and domain II appears to be primarily responsible for an energy-requiring step in the catalytic cycle unique to the degradation of large proteins.

Effect of rifampicin on theophylline pharmacokinetics in human beings

Theophylline pharmacokinetics before and after rifampicin administration was studied in 10 healthy volunteers. It was seen that Rifampicin significantly increased the volume of distribution of theophylline by 23.41% (p < 0.01) and its metabolic clearance by 47.65% (P < 0.05). This has got clinical significance in the treatment of patients of pulmonary tuberculosis with chronic obstructive airways disease where both the drugs may have to be given concurrently.

Quantification of 2,3-dihydro-7-methoxypyrrolo-[2,1-b]-quinazolin-9(1H)-one, a new antiallergic agent, by high-performance liquid chromatography in serum

The CDRI compound 73/602 (I, 7-methoxydeoxyvasicinone) is an antiallergic agent presently undergoing Phase II clinical trials. A rapid, precise and sensitive high-performance liquid chromatographic assay has been developed and validated for the detection of I in rat serum. The method involves extraction of rat serum samples with diethyl ether after addition of 1 M potassium hydroxide. Separations were accomplished on a RP-18 column using acetonitrile-phosphate buffer (pH 7) (20:80, v/v) as the mobile phase. Recovery of I was always > 90%. An excellent linear relationship (r = 0.9999) was obtained between the quantified and added concentrations over the range of 2.5 to 500 ng/ml. The sensitivity of the assay for 0.5 ml serum was 2.5 ng/ml.

Processive degradation of proteins by the ATP-dependent Clp protease from Escherichia coli. Requirement for the multiple array of active sites in ClpP but not ATP hydrolysis

ClpP, the proteolytic component of the ATP-dependent ClpAP protease, is composed of 12 identical subunits and has intrinsic degradative activity against short peptides. Degradation of proteins and some peptides by ClpP requires the regulatory component ClpA and ATP. Peptide and protein substrates have been used to distinguish the roles of nucleotide binding and nucleotide hydrolysis in the activation of ClpAP protease. ATP binding alone promoted interaction between ClpA and ClpP, affected the substrate response curves for very short peptides, and activated degradation of larger peptides that were not degraded by ClpP alone. ATP hydrolysis did not increase in proportion to the increase in peptide bond hydrolysis of short peptides. However, ATP hydrolysis was strictly required for degradation of proteins such as alpha-casein; there was no indication of even limited cleavage of protein substrates when nonhydrolyzable analogs of ATP were used. Most large peptides and proteins were degraded in multiple sites without release of high molecular weight intermediates. Partial inactivation of ClpP with diisopropyl fluorophosphate produced ClpP with one to three active subunits/dodecamer. When only a few active sites were available in the active complex of ClpAP, degradation of large peptides and proteins released significant amounts of high molecular weight intermediates. Thus, processive degradation of protein substrates is a function of the multiple array of proteolytic active sites within the ClpP dodecamer.

Immunoreactivity for bcl-2 protein in malignant mesothelioma and non-neoplastic mesothelium

Immunohistochemical study of bcl-2 protein immunoreactivity in human non-neoplastic mesothelium (44 cases) and in malignant mesothelioma (62 cases) using a murine monoclonal antibody (clone 124) showed cytoplasmic immunoreactivity for bcl-2 protein in five cases of malignant mesothelioma. Non-neoplastic mesothelium was not immunoreactive. Immunoreactivity for bcl-2 protein does not add useful prognostic information in malignant mesothelioma since survival times of bcl-2 positive and bcl-2 negative cases did not differ. Nevertheless, the detection of bcl-2 protein in malignant mesothelioma might be useful for the differentiation from reactive mesothelium.

Fine needle aspiration cytology in the management of acute suppurative thyroiditis

Acute suppurative thyroiditis (AST) is relatively uncommon. We report 11 such cases from a population residing in a goiter endemic zone of Northern India. The important contribution of fine needle aspiration cytology in confirming the diagnosis and management is emphasized.

Expression cloning of a mammalian proton-coupled oligopeptide transporter

In mammals, active transport of organic solutes across plasma membranes was thought to be primarily driven by the Na+ gradient. Here we report the cloning and functional characterization of a H(+)-coupled transporter of oligopeptides and peptide-derived antibiotics from rabbit small intestine. This new protein, named PepT1, displays an unusually broad substrate specificity. PepT1-mediated uptake is electrogenic, independent of extracellular Na+, K+ and Cl-, and of membrane potential. PepT1 messenger RNA was found in intestine, kidney and liver and in small amounts in brain. In the intestine, the PepT1 pathway constitutes a major mechanism for absorption of the products of protein digestion. To our knowledge, the PepT1 primary structure is the first reported for a proton-coupled organic solute transporter in vertebrates and represents an interesting evolutionary link between prokaryotic H(+)-coupled and vertebrate Na(+)-coupled transporters of organic solutes.

Parvalbumin-immunoreactive material in the kidney of Xenopus laevis

Parvalbumin-immunoreactive material has been localized in various parts of the Xenopus kidney. Ciliated epithelia in the neck segment, the intermediate segment and in the peritoneal funnel, epithelial cells intermingled among flask cells in the connecting tubule, and cells in the proximal and distal tubules cells were labelled. Renal corpuscle and collecting duct cells did not exhibit parvalbumin immunoreactivities. Western-blot analysis of kidney homogenates indicated various isoforms of parvalbumin-immunoreactive proteins.

Outside-in transscleral fixation for ciliary sulcus intraocular lens placement

We describe a new technique of transscleral intraocular lens fixation in the absence of adequate posterior capsular support. This technique of suture placement within the ciliary sulcus employs routinely used instruments, requires minimum manipulation, and has good visual outcome and negligible complications. We performed five intraocular lens implantations using the technique with good visual outcomes in each. No significant intraoperative or postoperative complications were noted.

Examination stress in medical student: a study

The present study was conducted on 40 male and 10 female students appearing for the 1st MBBS examination. Two readings of pulse rate, blood pressure and electro cardiogram were taken viz 6 months (control) and 10 minutes prior to the examination. A significant increase was seen in the pulse rate and blood pressure readings before the examination as compared to the control readings. However, no significant change was observed in electro cardiographic recordings.