Popliteal Aneurysms: Does Size Matter ?

When considering the management of popliteal aneurysms, not only the size but also the nature, symptoms and state of collateral and distal circulation must be taken in to account. We present a patient who required operative management of a symptomatic 3cm popliteal aneurysm of the left leg whilst a conservative approach chosen for the right leg which had an asymptomatic 17 × 13.1 cm popliteal aneurysm, the largest of its kind reported within the English literature.

Passive, opportunistic wildlife disease surveillance in the Rocky Mountain Region, USA

Wild animals can play an important role in the epidemiology of infectious disease with significant public health, economic and ecological consequences. As it is often challenging to conduct unbiased surveillance in free-ranging mammal populations, passive, opportunistic case identification has been widely used for detection of disease events in wild animals. This study evaluated the role of different agencies and organizations in the Rocky Mountain Region of the USA to identify significant wildlife health events or aggregate information from multiple sources. Overall wildlife rehabilitators were in contact with the greatest number of animals; however, the data from these groups, in its current state, are insufficient for surveillance purposes. Wild animal data from all survey groups aggregated at the level of state wildlife organizations; these agencies are therefore central in this type of surveillance activity and require sufficient resources to ensure that appropriate testing is conducted.

RBx 7796: A novel inhibitor of 5-lipoxygenase

OBJECTIVE

To evaluate the pharmacological profile of RBx 7,796, a novel 5-lipoxygenase inhibitor.

MATERIALS AND METHODS

RBx 7,796 was evaluated for 5- lipoxygenase inhibitory potential using human recombinant enzyme and profiled for selectivity against 12 and 15 lipoxygenase. RBx 7,796 was evaluated in cell based assay for inhibition of A23,187 induced LTB(4) release from isolated neutrophils. Ex vivo activity was evaluated for inhibition of A23,187 induced LTB(4) release in blood from treated rats. In vivo efficacy of RBx 7,796 was profiled in LPS induced neutrophilia model in rats and also in ovalbumin induced bronchoconstriction and airway inflammation models in guinea pigs.

RESULTS

RBx 7,796, a novel chemotype, showed competitive inhibition of 5-lipoxygenase enzyme with an IC(50) of 3.5 +/- 1.1 microM. RBx 7,796 offered >100 fold selectivity against other related enzymes - 12 and 15 lipoxygenase. RBx 7,796 inhibited release of LTB(4) from human and rat neutrophils in vitro. Upon administration to rats, RBx 7,796 inhibited A23,187 induced LTB(4) release from rat neutrophils. Upon repeated administration, dosed once daily, RBx 7,796 inhibited LPS induced neutrophil influx in rat airway. RBx 7,796 also inhibited allergen induced bronchoconstriction and eosinophil influx in guinea pig airway in a dose dependent manner.

CONCLUSION

The results suggest that RBx 7,796, a novel chemotype, is an orally efficacious inhibitor of 5-lipoxygenase enzyme that is effective against both neutrophilic and eosinophilic airway inflammation and shows potent inhibition with once daily administration.

Occult renal impairment is common in patients with peripheral vascular disease and normal serum creatinine

OBJECTIVE

The incidence of peripheral vascular disease (PVD) and angiography/angioplasty is rising annually. The UK Small Aneurysm Trial and other trials have shown renal function is a predictor of increased mortality and failed infrainguinal bypass despite patent vessels. Renal function is classically assessed by serum creatinine (SCr). However, SCr can be normal despite significant renal impairment. A more sensitive test is creatinine clearance (CrCl) as determined by 24-hour urine collection in combination with SCr. We studied the incidence of renal impairment, as defined by CrCl, in PVD patients with normal SCr.

METHODOLOGY

All patients with PVD sufficient to necessitate angiography and normal SCr (< or =120 micromol/l - men; < or =97 micromol/l - women) had their CrCl assessed prior to angiography: using both 24-hour urine collection and the Cockcroft-Gault formula. Various blood tests, a detailed history and examination were performed. A control group of arthritic patients, age and sex-matched with similar SCr, also had their CrCl determined.

RESULTS

65 of 76 patients (86%) with normal SCr had a subnormal CrCl (<100 ml/min) and 49 (65%) had a CrCl below 60 ml/min. In the control group of arthritic patients, the proportion having impaired CrCl was significantly less - 67% below 100 mls/min (p=0.0471) and only 15% below 60 mls/min (p<0.0001). The median and interquartile range CrCl of 52 [38-81] mls/min for PVD patients was significantly worse than for control patients (80 [68-119] mls/min -p<0.0001). The Cockcroft-Gault formula for calculating CrCl did not correlate well with the urinary CrCl for the control group but did for PVD patients (p<0.0001). Factors associated with a significantly reduced CrCl were age of at least 75 years, SCr of at least 85 micromol/l and a history of coronary heart disease (all p<0.05). This had a sensitivity of 88% and specificity of 82% for identifying subnormal CrCl. Statin use was associated with a significantly improved CrCl (p=0.040).

CONCLUSION

Most PVD patients with normal serum creatinine have occult, significantly impaired renal function as defined by creatinine clearance. Vascular surgeons should include creatinine clearance in pre-operative assessment of renal function especially in patients over 75 years old, with a history of coronary heart disease or a serum creatinine over 85 micromol/l. The method of determining creatinine clearance could be the Cockcroft-Gault calculation or ideally 24-hour urinary creatinine clearance measurement. This would allow appropriate early referral to a nephrologist for further investigation and management. It is worth noting that statin use seems to be associated with a protective effect on renal function.

Changing trends in drug resistance among typhoid salmonellae in Rawalpindi, Pakistan

We analysed the record of blood cultures carried out at the Armed Forces Institute of Pathology, Rawalpindi between 1996 and 2003. We isolated 477 Salmonella typhi and 410 S. paratyphi A from blood of patients suffering from typhoid fever. We observed a significant shift in the distribution and antimicrobial susceptibility of typhoid salmonellae. The isolation rate of S. typhi fell significantly while S. paratyphi A is emerging as a major pathogen. Resistance to conventional antityphoid drugs in S. typhi decreased dramatically from 80% to 14%, while in S. paratyphi A resistance increased from 14% to 44%. Susceptibility to the fluoroquinolones decreased in both. No resistance to third generation cephalosporins was detected.

The construction and evaluation of a questionnaire to identify quantitative criteria for evaluating national Veterinary Services

This article presents the first part of a large-scale study aimed at developing a method for collecting standard information, based on quantitative criteria, about the national Veterinary Services of Member Countries of the OIE (World organisation for animal health). This information can then be used to assess such Veterinary Services in terms of quality and performance, or for accreditation. The study identified objective and relevant criteria for characterising Veterinary Services and an extensive questionnaire was developed, covering all aspects of the structures and functions of national Veterinary Services, which was sent to a broad range of OIE Member Countries. Each question and its answers were then evaluated and validated. In this way, 49 questions suitable for obtaining quantitative criteria to describe Veterinary Services were identified. In the next step of the study, this complex set of data will be further analysed.

The role of veterinary epidemiology and veterinary services in complying with the World Trade Organization SPS agreement

The agreement on the application of sanitary and phytosanitary measures (SPS agreement) was one of the major products of the GATT's Uruguay round of multilateral trade negotiations, signed in Marrakesh on 15 April 1994. This agreement and others are part of the treaty that established the World Trade Organization (WTO). The WTO superseded the GATT as the umbrella organization for international trade (WTO, 1998a). The SPS agreement's main intent is to provide guidelines and provisions to member countries to facilitate trade while taking measures to protect human, animal or plant life or health. The agreement dictates that all sanitary measures must be scientifically based and not more restrictive than required to avoid the risk identified. The agreement recommends the use of international standards from the World Organization for Animal Health (OIE), Codex Alimentarius (CAC) and the International Plant Protection Convention (IPPC) as the basis for import requirements. If a country chooses to apply more restrictive measures than those in the international standards, it has to justify its position through a risk analysis, thus avoiding the use of sanitary and phytosanitary measures as unjustified barriers to trade. More than ever, veterinary services worldwide are faced with having to fulfill a crucial role in protecting their country's animal health status, provide sound surveillance information on the occurrence of diseases within their territories, and conduct scientifically valid risk analyses to establish justified import requirements. During the past two decades, most countries have experienced resource reduction in their veterinary services. The effect of these policies has been severe, in many cases leading to an inability of veterinary services to conduct their disease prevention and control duties. There is a clear inconsistency between the demands placed on veterinary services and the current level of funding and support they are receiving, particularly in the developing world. This paper analyzes the implications in complying with the SPS agreement and explores the role of veterinary epidemiology in developing viable alternatives that can enhance the veterinary services' ability to perform under the current economic reality. The key provisions of the SPS agreement are regionalization, risk analysis, harmonization, equivalence and transparency. The paper focuses on the contribution of epidemiology in each of these areas in the effective implementation of the SPS agreement.

Will the new cytogenetics replace the old cytogenetics?

With the advent of array-based comparative genomic hybridization technology, the analog cytogenetic analysis that has been used for the past 100 years could be replaced by the quantitative, microarray-based molecular analysis. Major advantages of the new array-based cytogenetic technologies are the high resolution and the high throughput. This technology is the first to offer an autonomous whole-chromosome analysis in one hybridization reaction for the detection of submicroscopic gains/losses. However, as with any new technology, it needs to be validated with regard to its performance in various applications (e.g. clinical genetic testing and cancer applications), comparative cost, and the data interpretation.

Applied animal behavior and obedience training course: a model for veterinary curricula

Animal behavior problems often have detrimental effects on the relationships between pets and their owners and are one of the most frequently given reasons for canine relinquishment. The stressful environment of animal shelters can exacerbate behavior problems; yet most shelters do not have the staff necessary to address this issue adequately. Veterinary students may provide an untapped resource for solving this dilemma. As a service component of the curriculum, Veterinary schools can join with local humane societies to expose students to behavioral issues and concurrently build relationships within the community and perhaps even offer shelter animals a better chance of successful adoption. The following paper describes a "hands-on" undergraduate animal behavior and obedience training psychology course, created as a model to address these needs.

International trade, animal health and veterinary epidemiology: challenges and opportunities

The link between international trade, animal health and epidemiology has been recognized for a long time and has taken an additional importance in the aftermath of the Uruguay Round of Multilateral Trade Negotiations of the General Agreement on Tariffs and Trade (GATT) and of the inception of the World Trade Organization. The Agreement on the Application of Sanitary and Phytosanitary Measures of the World Trade Organization demands that sanitary and phytosanitary measures be scientifically based, placing epidemiology at the center of decisions related animal health and trade. This paper analyses the interactions between international trade of animals (and animal products) and epidemiology with discussion on the inputs of epidemiology in surveillance, risk analysis and regionalization.

Longitudinal studies in the epidemiology of vesicular stomatitis on Costa Rican dairy farms

Twenty-three Costa Rican dairy herds from an vesicular stomatitis (VS) endemic area were under an active surveillance between April 1997 and March 1999. Ninety-two confirmed cases of VS New Jersey were found. Factors associated with clinical cases of VS virus New Jersey were: Parity (animals of parity 4 or 5 were 5.3 times more likely to present a clinical case than animals of parity 3 and lower; on the other hand, animals of parity 6 and higher showed an odds 4.6 times greater than animals of parity 3 and lower.) Ecological life zone (animals in premountain moist forest were 7.4 times more likely to present clinical cases than animals in lower mountain rain forest). Factors associated with seropositivity at the time of birth were farm and breed (Jersey calves had an odds 14.7 times greater than Holstein calves). Seroconversion, defined as the first twofold increase in the titers of the blood, was associated with farm and showed four peaks during the study period, September (wet season) 1997, February (dry season) 1998, September 1998, and February 1999. Finally, time to event analysis showed difference between farms and age, older animals showed the first seroconversion earlier than younger animals.

Survey of small rodents and hematophagous flies in three sentinel farms in a Costa Rican vesicular stomatitis endemic region

A survey of rodents and hematophagous flies was conducted on three farms located in an area endemic for vesicular stomatitis to determine the species composition of each zoological group occurring in these areas. Eleven species of small rodents were collected and identified. Individuals from forty-nine species of hematophagous flies of the families Ceratopogonidae, Culicidae, and Phlebotominae were captured and identified. The species compositions in each group were compared between farms. Rodents were tested for antibodies to vesicular stomatitis, New Jersey and Indiana serotypes. Seven species had antibody titers greater than 1:10. Attempts to isolate the virus produced negative results for all the species tested.

Quantitative evaluation of imagent as an abdominal ultrasound contrast medium in dogs

Diagnostic ultrasound currently provides a noninvasive, economical means to evaluate internal organ structure. Methods to increase the amount of diagnostic information obtained from the sonographic examination are being explored. A new area of research has recently focused on the ability of microbubble contrast agents to help provide additional information. A prospective study was undertaken to quantitatively evaluate the amount of gray scale enhancement of ultrasound images of six canine livers, spleens, and left kidneys that occurs after intravenous injection of Imagent. Computerized analysis was used to assess the percent change in brightness of these images. A transient decrease in the percent change in brightness was seen to occur after injection of higher doses of Imagent. This effect was more pronounced in the deeper portions of the organs of interest. Imagent provides a measurable change in the brightness of the organs of interest and would be potentially useful in a clinical setting.

Why does tonsillar herniation not occur in idiopathic intracranial hypertension?

Idiopathic intracranial hypertension (IHH or pseudotumor cerebri) is an uncommon but important cause of headache, characterized by raised intracranial pressure (ICP) in the absence of infection and intracranial pathology on neuroimaging. Lumbar puncture (LP) is usually contra-indicated in situations where the ICP is suspected to be high. However, tonsillar herniation is hardly ever reported after an LP in patients suspected of having IHH. The author postulates that increasing brain stiffness reported in IHH may be the reason for this observation. On the other hand, tonsillar herniation may occur as a late complication following lumbo-peritoneal shunt insertion (occasionally used in the management of patients with IHH). This may be due to the decrease in brain stiffness, i.e. an increase in brain compliance as the condition improves following shunt insertion. Recent advances in magnetic resonance imaging techniques are likely to help us further in understanding the pathogenesis of this curious condition.

Dot immunobinding assay for detection of bovine herpesvirus 4 antibodies in rabbits

A dot immunobinding assay (DIA) was used for the detection of antibody against bovine herpesvirus 4 (BHV-4) in experimentally infected specific-pathogen-free male and female rabbits. A semipurified virus preparation was used as the antigen, and protein A/G-horseradish-peroxidase conjugate and diaminobenzidine tetrahydrochloride were used as the detection system. Results of the DIA procedure on serum samples of experimentally infected male and female rabbits were compared with those of a complement-dependent virus neutralization (VN) test. None of the tested sera (0/60 samples) from either male or female rabbits were positive by the complement-dependent VN test. Results of the DIA procedure for the same tested sera were positive in 35 of 60 samples (58%) from BHV-4 infected rabbits, indicating higher sensitivity of DIA procedure as compared with the complement-dependent VN test.

Synthesis of mycolic acids of mycobacteria: an assessment of the cell-free system in light of the whole genome

Mycolic acids are 70-90 carbon, alpha-alkyl, beta-hydroxy fatty acids constituting a major component of the cell envelope of Mycobacterium tuberculosis. The fact that the mycolic acid biosynthetic pathway is both essential in mycobacteria and the target for many first-line anti-TB drugs necessitates a detailed understanding of its biochemistry. A whole cell-free, but cell particulate- and membrane-containing enzyme preparation for mycolic acid biosynthesis was developed a few years ago and studied extensively. This system was shown to catalyze the synthesis of mature mycolic acids from [14C]acetate, but allows only minimal deposition into the cell wall proper. In the meantime the sequence of the entire genome of M. tuberculosis has been elucidated and its analysis using numerous protein sequence-based algorithms predicted cytoplasmic localization and a soluble, not a particulate, nature for the enzymes involved in the mycolic acid synthetic pathway. Accordingly, we re-assessed the 'cell-free' system for mycolic acid synthesis and concluded that it is probably due to the presence of unbroken cells, since viable cells were recovered from the cell wall preparation. The amount of whole cells depended upon the efficiency of the cell disruption method and conditions, and the amount of mycolic acid synthesized by the putative cell-free system correlated with the content of whole cells. Thus, accumulated results from the use of this 'cell-free' cell wall-based system should be re-evaluated in the light of these new data.

Phosphatidylinositol synthesis in mycobacteria

The metabolism and synthesis of an important mycobacterial lipid component, phosphatidylinositol (PI), and its metabolites, was studied in Mycobacterium smegmatis and M. smegmatis subcellular fractions. Little is known about the synthesis of PI in prokaryotic cells. Only a cell wall fraction (P60) in M. smegmatis was shown to possess PI synthase activity. Product was identified as PI by migration on TLC, treatment with phospholipase C and ion exchange chromatography. PI was the only major product (92.3%) when both cells and P60 fraction were labeled with [3H]inositol. Also, a neutral lipid inositol-containing product (4.1% of the total label) was identified in the P60 preparations. Strangely, PI synthase substrates, CDP-dipalmitoyl-DAG and CDP-NBD-DAG, added to the assay did not stimulate [3H]PI and NBD-PI yield by M. smegmatis. At the same time, addition of both substrates to rat liver and Saccharomyces cerevisiae PI synthase assays resulted in an increase in the product yield. Upon addition of CHAPS to the mycobacterial PI synthase assay, both substrates were utilized in a dose-dependent manner for the synthesis of NBD-PI and [3H]PI. These results demonstrate a strict substrate specificity of mycobacterial PI synthase toward endogenous substrates. K(m) of the enzyme toward inositol was shown to be 25 microM; Mg2+ stimulated the enzyme to a greater degree than Mn2+. Structural analogs of myo-inositol, epi-inositol and scyllo-inositol and Zn2+ were shown to be more potent inhibitors of mycobacterial PI synthase than of mammalian analogs. Lack of sequence homology with mammalian PI synthases, different kinetic characteristics, existence of selective inhibitors and an important physiological role in mycobacteria, suggest that PI synthase may be a good potential target for antituberculosis therapy.

Outcome of congenital hydronephrosis in qatar

Three hundred and eleven patients diagnosed to have congenital hydronephrosis proven by postnatal ultrasonography in a ten-year period between 1987 and 1996 were studied retrospectively. These were classified into mild degree of hydronephrosis in H (64%), moderate in 94 (30%) and severe in 18 (6%) patients, according to first post natal sonography and depending on the measurement of the anterio-posterior transverse diameter of the pelvi-calyceal system. Significant obstructive uropathy was documented in 66 patients by Technetium-Diethylene triamine penta acetic acid renogram (Tc99m DTPA Renogram Vesicoureteric reflux was found in 22 patients by voiding cysto-urethrogram. On follow-up the hydronephrosis regressed spontaneously in 99 (31.8%), was stable in 167 (53.6%) and needed operative intervention in 45 (14.4%) patients. The types of surgical operations were pyeloplasty in 49% and ureteric re-implantation in 27%. Fifteen (83%) of the children with severe hydronephrosis and 32 (34%) of the moderate hydronephrosis group were operated o while none of the children with the mild form required operative intervention. We recommend ultrasound follow-up for mild hydronephrosis and a coordinated approach and work-up for congenital moderate and severe hydronephrosis. Surgery should only be considered if renal function is affected.

Use of a fluorescent analog of CDP-DAG in human skin fibroblasts: characterization of metabolism, distribution, and application to studies of phosphatidylinositol turnover

We studied the uptake metabolism, and distribution of a fluorescent analog of CDP-diacylglycerol [cytidine diphosphate-1, 2-oleoyl, (N-(4-nitrobenzo-2-oxa-1,3-diazole) aminocaproyl) diacylglycerol; CDP-NBD-DAG]. When cells were incubated with CDP-NBD-DAG for 60 min at 11 degrees C and washed, the fluorescent lipid was localized to the plasma membrane. However, upon warming to 37 degrees C, the fluorescent lipid redistributed into various intracellular membranes and was metabolized primarily to fluorescent analogs of DAG and phosphatidylcholine (PC), although small amounts of fluorescent phosphatidic acid and phosphatidylinositol (PI) were also formed. The incorporation of 32Pi into some of the fluorescent lipids was also determined in order to assess their turnover. Stimulation of cells with platelet-derived growth factor enhanced the synthesis of fluorescent PI relative to unstimulated cells by approximately 68%, while the synthesis of fluorescent PC was unaffected. In addition, the incorporation of 32Pi into fluorescent PI was enhanced. Stimulation of cells with interleukin-1 beta enhanced the synthesis of both fluorescent PI (approximately 88%) and PC (approximately 250%) compared to non-stimulated cells, but with less incorporation of 32Pi into fluorescent PI. Finally, incubation of CDP-NBD-DAG-treated cells with inhibitors of phosphatidic acid phosphohydrolase and DAG kinase resulted in a dramatic increase in the amount of fluorescent PI formed (approximately 64% of all the CDP-NBD-DAG metabolites). We conclude that CDP-NBD-DAG can be used for the de novo synthesis of fluorescent PI, and in combination with 32P labeling, provides a convenient method for studying PI turnover.

A distinctive overgrowth syndrome with polysyndactyly

We report a female infant with 3-4 syndactyly of the fingers and postaxial polydactyly of all four limbs. She was large at birth and died at the age of 6 months.

Antiinflammatory C-glucosyl chromone from Aloe barbadensis

A new antiinflammatory agent identified as 8-[C-beta-D-[2-O-(E)-cinnamoyl]glucopyranosyl]-2- [(R)-2-hydroxypropyl]-7-methoxy-5-methylchromone (1) has been isolated from Aloe barbadensis Miller. At a dose of 200 microg/mouse ear, 1 exhibited topical antiinflammatory activity equivalent to 200 microg/ear of hydrocortisone. There was no reduction in thymus weight caused by treatment with 1 for any of the doses tested, while 200 microg/ear of hydrocortisone resulted in a 50% decrease in thymus weight.

Effects of halothane on glutamate receptor-mediated excitatory postsynaptic currents. A patch-clamp study in adult mouse hippocampal slices

BACKGROUND

The effects of halothane on excitatory synaptic transmission in the central nervous system of mammals have been studied in vivo and in vitro in several investigations with partially contradicting results. Direct measurements of the effects of halothane on isolated glutamate receptor-mediated (glutamatergic) excitatory postsynaptic currents (EPSCs), however, have not been reported to date.

METHODS

The effects of halothane on glutamatergic EPSCs were studied in vitro by using tight-seal, whole-cell recordings from CA1 pyramidal cells in thin slices from the adult mouse hippocampus. The EPSCs were pharmacologically isolated into their non-N-methyl-D-aspartate (non-NMDA) and NMDA receptor-mediated components by using selective antagonists. The effects of halothane on EPSC amplitude and kinetics were analyzed at various membrane potentials and were compared with its effects on currents evoked by exogenously applied glutamatergic agonists.

RESULTS

Halothane (0.2-5.1%; 0.37-2.78 mM) reversibly blocked non-NMDA and NMDA EPSCs. This effect was voltage independent; concentrations producing 50% inhibition were 0.87% (0.66 mM) and 0.69% (0.57 mM), respectively. Currents induced by bath-applied glutamatergic agonists were not affected even by the high concentrations of halothane.

CONCLUSIONS

Halothane depresses glutamatergic EPSCs irrespective of receptor subtype, most likely by inhibition of glutamate release.

The cell membrane of Mycoplasma penetrans: lipid composition and phospholipase A1 activity

Analysis of Mycoplasma penetrans membrane lipids revealed that, in addition to large amounts of unesterified cholesterol, M. penetrans incorporated exogenous phospholipids, preferentially sphingomyelin, from the growth medium. The major phospholipids synthesized de novo by M. penetrans were phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG). In vivo labeling of PG and DPG by growing the cells with radioactive palmitate or oleate, followed by snake venom phospholipase A2 treatment, enabled us to assess the positional distribution of fatty acids in these lipids. Saturated fatty acids were found preferentially in position 2 of the glycerol backbone, and not in position 1 as found elsewhere in nature, while unsaturated fatty acids prefer position 1. M. penetrans membranes contain phospholipase activity of the A1 type, removing a fatty acid from the sn-1 ester bond of phospholipids. The activity was neither stimulated by Ca2+ nor inhibited by EGTA and had a broad pH spectrum. The substrate specificity of the enzyme was investigated with various natural lipids and with a fluorescent analog of the phosphatidylcholine. The enzyme was equally active toward phosphatidylcholine and phosphatidylglycerol, but did not hydrolyze diphosphatidylglycerol. The enzyme did not act on triacylglycerol, diacylglycerol or cholesteryl ester, but low activity was detected toward monoacylglycerol. The enzyme was heat-sensitive and detergent-sensitive, and was almost completely inhibited by p-bromophenacylbromide (50 microM), but was not affected by SH reagents. This study is the first one reporting phospholipase A1 activity in Mollicutes. A possible role of this enzyme in forming lipid mediators upon the interaction of M. penetrans cells with eukaryotic cells is suggested.

An unusual polar lipid from the cell membrane of Mycoplasma fermentans

The major unidentified polar lipid (compound X), recently demonstrated in the cell membrane of Mycoplasma fermentans, was purified by preparative silicic acid column chromatography. Chemical analyses of acid-hydrolyzed compound X revealed that, in addition to fatty acids, it contains glycerol, choline and phosphate in a molar ratio of approximately 1:1:2, and an amino acid that has a retention time similar to that of homoserine. The methylated fatty acid fraction of compound X was subjected to gas-liquid chromatography and revealed methyl palmitate and methyl stearate in a 4.6:1 molar ratio. The structure of compound X was further analyzed by combining mass spectrometry, 31P-NMR and 1H-NMR. The positive and negative fast atom bombardment spectra showed a major component of M(r) 1048 and a minor component of M(r) 1076. Two different phosphate groups were identified in each of the components by 31P-NMR. Fast atom bombardment, tandem mass spectrometry, negative and positive chemical ionization mass spectrometry together with mass spectra analyses of the water-soluble and ether-soluble products obtained by methanolysis has shown that, in addition to palmitic and stearic acid residues, the presence of glycerol, ribitol, cholinephosphate and homoserinephosphate residues. It is suggested that the apparent structure of compound X is either a phosphatidylcholine attached via a phosphotriester bond to a ribitolphosphohomoserine moiety or a phosphatidylhomoserine attached via a phosphotriester bond to a ribitolphosphocholine moiety. The major molecular species is the dipalmitoylderivative (M(r) 1048), whereas the minor molecular species is a stearoyl palmitoyl derivative (M(r) 1076).

Idiopathic dilated cardiomyopathy in dogs: survival and prognostic indicators

To further define the prognosis and identify clinical findings predictive for survival in dogs with dilated cardiomyopathy (DCM), we performed Kaplan Meier survival analysis of 37 dogs with idiopathic DCM. Survival analysis showed that the 50% probability of survival occurred at 2.3 months. Probability of survival at 1 year was 37.5% and at 2 years was 28%. Bivariate Cox proportional hazard ratios identified pleural effusion and pulmonary edema, both signs of congestive heart failure, as independent prognostic indicators for dogs with DCM (P < .01). Hazard ratios for these prognostic indicators were 2.354 and 3.291, respectively. Multivariate Cox stepwise regression identified pleural effusion, left ventricular free-wall thickening fraction, ventricular ectopy, and weight loss as significant prognostic indicators for dogs with DCM. Because of the retrospective nature of this study, the effects of different drug treatments were not evaluated. The type of cardiac-related death, progressive failure versus sudden death, was not addressed in this study and requires further evaluation.

Membrane lipids of Mycoplasma fermentans

Membranes of Mycoplasma fermentans, incognitus strain, were isolated by a combination of osmotic lysis and sonication. Analysis of membrane lipids revealed, in addition to free and esterified cholesterol, six major polar lipids dominated by a de novo synthesized compound (compound X), which accounts for 64% of the total lipid phosphorus. Compound X was labeled by palmitate, but not by oleate. Mass spectrometry and gas liquid chromatography analyses of compound X revealed two molecular species with molecular masses of 1048 and 1076 representing, a dipalmitoyl- and a stearoyl-palmitoyl-glycerodiphosphatidylcholine. Compound X has the ability to stimulate human monocytes to secret TNF alpha and to enhance the fusion of small unilamellar vesicles with MOLT-3 lymphocytes.

Fusion of Spiroplasma floricola cells with small unilamellar vesicles is dependent on the age of the culture

Small unilamellar vesicles were labeled with the fluorescent probe octadecylrhodamine B chloride and mixed with intact Spiroplasma floricola cells. The increase in fluorescence observed was interpreted as a result of the dilution of the probe in the unlabeled S. floricola membranes because of lipid mixing upon fusion. The progression of S. floricola cultures to the stationary phase of growth was accompanied by a sharp decrease in the ability of the cells to fuse with small unilamellar vesicles. Low fusogenic activity was also detected in cells from cultures that were aged in a growth medium maintained at pH 7.5 throughout the growth cycle. Chemical analysis of the cell membrane preparations isolated from cells harvested at the various phases of growth revealed that the phospholipid content and composition and the cholesterol/phospholipid molar ratio were changed very little upon aging of the cultures. Likewise, no changes in the fatty acid composition of membrane lipids were detected, with palmitic and oleic acids predominating throughout the cycle. Nonetheless, upon aging of S. floricola cultures, a pronounced increase in the levels of both cholesteryl esters, incorporated from the growth medium, and organic peroxides was observed. A decrease in both fluorescence anisotropy of diphenylhexatriene and merocyanine 540 binding to membranes of aged cells was also detected. The possible influence of these changes on the fusogenic activity of the cells is discussed.

Mycoplasma fermentans (incognitus strain) cells are able to fuse with T lymphocytes

Characteristics of the fusion of Mycoplasma fermentans (incognitus strain) with cultured lymphocytes were investigated. The rate and extent of fusion were monitored continuously in an assay that measured lipid mixing on the basis of dequenching of a fluorescent probe, octadecylrhodamine (R18), incorporated into mycoplasmas. Fusion of M. fermentans was detected with CD4+ (Molt-3) cells, CD4- (12E1) cells, and primary peripheral-blood lymphocytes. The level of fusion was relatively low (8%-12%). Detection of a similarly low level of fusion by fluorescence microscopy suggested the involvement of a specific lymphocyte subpopulation. After a short lag period, fusion at 37 degrees C proceeded exponentially for approximately 30 minutes and was virtually complete at 60 minutes. Throughout the process, lymphocytes remained intact. Fusion was stimulated by CaCl2 but not by MgCl2; its inhibition by antisera to M. fermentans and by pretreatment of M. fermentans with proteolytic enzymes implied that the mycoplasmas possessed a proteinase-sensitive receptor involved in fusion. Mycoplasmas were rendered nonfusogenic by treatment with the uncoupler CCCP (carbonyl cyanide m-chlorophenylhydrazone; 5 microM) but were unaffected by treatment with chlorpromazine (10 microM) or DCCD (dicyclohexylcarbodiimide; 50 microM); these findings suggested that a proton gradient across the cell membrane is required for fusion.

Cholesterol is required for the fusion of single unilamellar vesicles with Mycoplasma capricolum

Small unilamellar vesicles (SUV) were prepared from the total lipid extract of Mycoplasma capricolum. The SUV were labeled with the fluorescent probe octadecylrhodamine B chloride (R18) to a level at which the R18 fluorescence was self-quenched. At pH 7.4 and 37 degrees C, and in the presence of 5% polyethylene glycol, an increase in the R18 fluorescence with time was observed when the R18-labeled SUV were introduced to a native M. capricolum cell suspension. The fluorescence dequenching resulting from dilution of the R18 into the unlabeled membranes of M. capricolum, was interpreted as a result of lipid mixing during fusion between the SUV and the mycoplasma cells. The presence of cholesterol in the SUV was found to be obligatory to allow SUV-mycoplasma fusion to occur. Adaptation of M. capricolum cells to grow in a medium containing low cholesterol concentration provided cells in which the unesterified cholesterol content was as low as 17 micrograms/mg cell protein. The fusion activity of the adapted cells was very low or nonexistent. Nonetheless, when an early exponential phase culture of the adapted cells was transferred to a cholesterol-rich medium, the cells accumulated cholesterol and regained their fusogenic activity. The cholesterol requirement for fusion in the target mycoplasma membrane was met by a variety of planar sterols having a free beta-hydroxyl group, but differing in the aliphatic side chain, e.g., beta-sitosterol or ergosterol, even though these sterols, having a bulky side chain, are preferentially localized in the outer leaflet of the lipid bilayer. It is suggested that the role of cholesterol in mycoplasma-SUV fusion is not at the level of bulk bilayer viscosity but rather, affecting local lipid-lipid or lipid-protein interactions that are relevant to the fusion event.

Mycoplasma fermentans (incognitus strain) induces TNF alpha and IL-1 production by human monocytes and murine macrophages

We have demonstrated that Mycoplasma fermentans (incognitus strain), as well as M. fermentans KL4, PG 18 and IM 1 strains have the ability to activate human peripheral blood monocytes and murine macrophages of two inbred strains to secrete a high level of tumor necrosis factor alpha (TNF alpha) in a dose-dependent manner. Secretion of interleukin-1 (IL-1) was also stimulated following the incubation of human monocytes with the organism. We suggest that cytokine secretion following infection with M. fermentans (incognitus strain) that was detected in AIDS patients may contribute to the pathological manifestations, including cachexia, in this disease.

Fusion-mediated transfer of plasmids into Spiroplasma floricola cells

We have developed and characterized a system for the transfer of plasmids encapsulated in large unilamellar vesicles (LUV) into Spiroplasma floricola BNR1 cells. The approach is based on the ability of S. floricola-derived LUV to fuse with S. floricola cells. The fusion was continuously monitored by an assay for lipid mixing based on the dequenching of the fluorescent probe octadecylrhodamine B (R18) that was incorporated into LUV at self-quenching concentrations. The fusion was also evaluated by fluorescence-activated cell sorter measurements and by sucrose density gradient analysis. LUV-cell fusion occurred only in the presence of low concentrations (5%) of polyethylene glycol (polyethylene glycol 8000) and depended on temperature, the LUV/cell ratio, and divalent cations in the incubation medium. Throughout the fusion process, spiroplasma cells remained intact and viable. Under optimal fusion conditions, the plasmid pACYC, encapsulated in LUV by reversed-phase evaporation, was transferred into live S. floricola cells and expressed chloramphenicol acetyltransferase activity. The expression was transient with maximal chloramphenicol acetyltransferase activity observed after 6 h of incubation of the transfected cells.

Uptake of a fluorescent-labeled fatty acid by spiroplasma floricola cells

12-(1-pyrene)dodecanoic fatty acid (P12) uptake by Spiroplasma floricola BNR-1 cells was characterized with regard to its kinetics, specificity, metabolism and susceptibility to protein and lipid inhibitors. The uptake process depended on temperature and pH, and exhibited biphasic saturation kinetics with a very low (2.7 microM) and a high (37 microM) apparent Km value. Lauric, myristic, palmitic, stearic and oleic fatty acids did not compete with P12 for transport. The fluorescence of P12 was exclusively recovered in the neutral lipid fraction, suggesting that this fatty acid is not further utilized for phospholipid biosynthesis. Valinomycin, carbonylcyanide m-chlorophenyldrazone (CCCP), dicyclohexylcarbodiimide (DCCD), and pronase strongly reduced P12 uptake by cells, but not by membrane vesicles, affecting the high affinity (low Km) component of the uptake system. Uptake of P12 by cells, as well as by membrane vesicles, was very sensitive to glutaraldehyde, chlorpromazine, phospholipase A21 and ascorbate with FeCl3, which affected the low affinity (high Km) component of a transport system. Digitonin stimulated P12 uptake. We suggest that the incorporation of P12 into spiroplasma cell membrane is a two-step process: a high specificity energy-dependent and protease-sensitive binding to the outer surface of membrane, and a low specificity and energy-independent diffusion and partition into the membrane lipid environment.

Fusion of mycoplasmas: the formation of cell hybrids

Poly(ethylene glycol) (PEG 8000) can induce cell-cell fusion of Mycoplasma capricolum cells, and it can promote the formation of intergeneric hybrids of various Mycoplasma, Acholeplasma and Spiroplasma species. The extent of fusion was quantitatively evaluated by following the dequenching of octadecylrhodamine fluorescent label incorporated into donor cell membranes after their incubation with recipient cells. The results of dequenching experiments were confirmed by electron microscopy, as well as by angle light-scattering measurements. Fusion appeared to require the presence of Mg2+, but was completely inhibited by either 0.1% glutaraldehyde or 100 microM chlorpromazine, and was partially suppressed by proteolytic enzymes, carbonyl cyanide-m-chlorophenylhydrazone, or thiol reagents.

17 alpha-substituted analogs of estradiol for the development of fluorescent estrogen receptor ligands

For the successful development of a high-affinity fluorophore-estradiol conjugate, the fluorophore must be attached to the estradiol molecule at a position that interferes least with its binding to the receptor. We have concentrated on 17 alpha substituents as models for fluorophore attachment, based on literature precedent and on our earlier work with small 17 alpha side chains. In this report, we describe syntheses and estrogen receptor binding affinities of 19 analogs of estradiol substituted in the 17 alpha position with larger side chains (of six to 11 carbons), some of which may be synthetically modified to link a fluorophore. These analogs were synthesized either by nucleophilic cleavage of estrone-17 beta-oxirane 3-benzyl ether and subsequent debenzylation (4 to 18), by cross-coupling of alkynes (21 to 24), by alkylation of 17 alpha-ethynylestradiol 3,17-bis(tetrahydropyranyl ether) and subsequent acidic hydrolysis (25 to 28), or by reacting estrone either with appropriate aryl/alkynyllithium reagents (29, 30, and 32) or with benzylmagnesium bromide (31). Relative binding affinities of these newly synthesized analogs were determined for estrogen receptor (rat uterus) using a standard competition assay. The results suggest that analogs with reduced mobility and/or more polarizable electron density in the side chain generally bind more strongly to the receptor. The relative affinities of several selected compounds were also determined in the presence of 4% dimethylformamide; some compounds bearing larger, nonpolar 17 alpha substituents showed dramatically improved affinities, while affinities for compounds with shorter nonpolar side chains remained largely unchanged. These binding affinity results should be useful in designing new high-affinity fluorescent ligands for the estrogen receptor.

Small unilamellar vesicles are able to fuse with Mycoplasma capricolum cells

We have investigated the fusion characteristics of intact Mycoplasma capricolum cells and small unilamellar vesicles (SUV). The rate and extent of fusion was monitored continuously by octadecylrhodamine B (R18) fluorescence dequenching assay, as well as by intracellular contents mixing, and by sucrose density gradient analysis. The fusion of SUV with M. capricolum cells was found to be dependent on poly(ethylene glycol) (PEG 8000), divalent cations in the medium, and on the cholesterol content of the lipid vesicles. Maximal levels of fusion were obtained with SUV containing 40 mol% cholesterol in the presence of 5% PEG. The rate and extent of fusion were affected by temperature, pH, osmotic pressure, and SUV/mycoplasma ratio. Under optimal fusion conditions, PEG did not increase the rate of exchange of either cholesterol or phospholipids between M. capricolum cells and SUV. Throughout the fusion process, M. capricolum cells remained intact as measured by the retention of [3H]thymidine-labeled components, and viable. M. capricolum cells were rendered nonfusogenic by treatment with glutaraldehyde (greater than 0.01%) or chlorpromazine (greater than 10 microM). Fusion was partially inhibited by treating the cells with the uncoupler CCCP (5 microM) or proteolytic enzymes, suggesting that a proton gradient across the cell membrane is required for the fusion, and that the cells possess proteinase-sensitive receptors that are responsible for a tighter contact with the lipid vesicles.

A potential radioiodinated ligand for androgen receptor: 7 alpha-methyl-17 alpha-(2'-(E)-iodovinyl)-19-nortestosterone

The presence of androgen receptor (AR) in prostate cancer has been linked to the androgen-dependent nature of the tumor and has also been shown to have prognostic significance; it also appears to be a positive prognostic indicator in breast cancer. However, due to the relatively low AR concentrations in most tumors and the inherently low specific activity of tritium, the assay of AR based on available 3H-ligands is not sensitive enough to measure accurately the amount of receptor in small specimens. A 125I-ligand like those available for the estrogen and progesterone receptors would be helpful, but development of such a ligand for AR has not been very successful. Although several androgen analogues containing iodine, bromine, or selenium have been synthesized specifically as potential probes for AR, none have shown any significant affinity or specificity for the receptor. We therefore undertook the synthesis of new potential AR ligands which could be radioiodinated, and determined their affinities for AR (from rat uterus and MCF-7 human breast cancer cells) by using a competition assay. We have examined both 5 alpha-dihydrotestosterone (5 alpha-DHT) and 19-nortestosterone analogues and have identified two such compounds which showed high AR affinity: (17 alpha,20E)-17 beta-hydroxy-21-iodo-5 alpha-pregn-20-en-3-one (17 alpha-[E)-iodovinyl)-5 alpha-DHT, 9) and 17 beta-hydroxy-7 alpha-methyl-(17 alpha,20E)-21-iodo-19-norpregna-4,20-dien-3- one (7 alpha-methyl-17 alpha-[E)-iodovinyl)-19-nortestosterone, 11). In fact, the affinity of the latter for human AR was found to be superior to that of 5 alpha-DHT itself. These iodovinyl analogues could be easily prepared in the radioiodinated form, and should prove to be extremely useful in assaying low levels of AR in small specimens.

125I-ligand for progesterone receptor: 17 alpha-(6'-iodohex-1'-ynyl)-19-nortestosterone

Progesterone receptor (PgR) is known to be a significant indicator of hormone dependency of a breast tumor and also an important prognostic factor for recurrence and survival. Relatively low specific activity of tritium-labeled ligands makes it difficult to detect the presence of PgR in very small specimens and in specimens with low PgR content. We therefore undertook the synthesis of a radioiodinated progestin. We have synthesized unlabeled 17 alpha-(omega-haloalk-1'-ynyl)-19-nortestosterones with 4, 6, and 8 carbon side chains; these have high affinity for PgR and clear potential for conversion to a 125I form. Since the six-carbon side chain analogue had the highest relative PgR affinity (38% of the affinity of R5020, using PgR from T47D human breast cancer cells), it was selected for preparation of the 125I form by radiohalogen exchange of a omega-bromoalkynyl precursor with carrier-free Na125I. This new ligand was found by Scatchard analysis to have a Kd of 0.47 nM, as compared with [3H]R5020 at 0.22 nM and [3H]progesterone at 2.0 nM. (For affinity studies, all ligands were diluted in dimethylformamide and added to PgR-containing T47D cytosol to give a final DMF concentration of 4%, in order to prevent R5020 and the test compounds from binding nonspecifically to proteins and glass/plasticware.) The new 125I-ligand showed very little instability when stored in ethanol at approximately 10 degrees C even for several months. Thus, 17 alpha-(6'-[125I]iodohex-1'-ynyl)-19-nortestosterone should prove to be a useful ligand for high sensitivity PgR assays.

A 46-kDa antigen associated with estrogen receptor in human breast cancer

A 65-kDa estrogen receptor (ER) protein has been demonstrated both by sucrose gradient analysis and by immunoblot, using anti-ER monoclonal antibodies (MAbs). Since the ER is denatured in many experimental situations, such as formaldehyde fixing of samples for histochemistry and electroimmunoblotting studies, in this work we used a denatured 60-70-kDa ER-rich protein preparation as antigen for mice immunization in order to raise anti-ER MAbs. That material was obtained by affinity purification on an allyl-estradiol matrix of the MCF-7 cytosolic ER, followed by further isolation and enrichment by PAGE. NS-1 myeloma cells and spleen lymphocytes from the immunized mice were fused, and resultant hybridoma colonies were screened by [125I]-estradiol-labelled nuclear ER immunoprecipitation. The isolated MAb, E476, shows a moderate ability to precipitate ER and reacts strongly with a 46-kDa antigen in Western blot assay. The 46-kDa antigen was not detectable in native cytosol but became reactive after 50% ammonium sulfate precipitation of cytosolic proteins. The 46-kDa antigen appeared concentrated in the NaSCN plus estradiol eluate of the affinity column used for cytosolic ER purification. Freshly prepared 60-70-kDa material from the preparative gel electrophoresis did not show any E476 reactivity. However, when the 60-70-kDa proteins were frozen, thawed and speed vacuum concentrated, the 46-kDa antigen became detectable. Storage increased the reactivity of the 60-70-kDa material with the E476 MAb. The 46-kDa antigen was present only in the ER positive cell lines, and was absent in all negative cell lines tested. The 46-kDa protein is also present in the ER positive human breast cancer specimens. We conclude that the 46-kDa protein identified with the E476 MAb in human breast cancer is probably a naturally occurring ER fragment.