Concentrating human milk: an innovative point-of-care device designed to increase human milk feeding options for preterm infants

OBJECTIVE

The purpose of this study was to determine whether a point-of-care osmotic device concentrates important human milk (HM) nutrients to support feeding neonates requiring high-nutrient, low-volume feedings.

STUDY DESIGN

Raw and pasteurized HM samples were concentrated to determine the effects of time and temperature on concentration. Concentrated samples were compared with matched baseline samples to measure changes in selected nutrient concentrations. Furthermore, changes in concentration of certain bioactive components of raw milk samples were measured.

RESULT

The device significantly increased the concentrations of the majority of the measured nutrient and bioactive levels (p < 0.05). Increasing temperature of HM from 4 to 37 °C increased the concentration rate >30%. In all cases, the concentration rate of pasteurized HM was greater than that of raw HM.

CONCLUSIONS

The osmotic concentration of HM is a promising option for neonatal nutrition. Further studies are needed to establish an evidence base for the practical applications of this point-of-care device.

Differential Stem Proteomics and Metabolomics Profiles for Four Wheat Cultivars in Response to the Insect Pest Wheat Stem Sawfly

Common wheat (Triticum aestivum L.) is a global staple crop, and insect pests can impact grain yield. The wheat stem sawfly (Cephus cinctus, WSS) is a major wheat pest, and while partial resistance has been deployed by breeding for a solid-stem trait, this trait is affected by environment. Here, a proteomics and metabolomics study was performed on four wheat cultivars to characterize a molecular response to WSS infestation. The cultivars Hatcher (hollow-stem partially tolerant), Conan (semisolid-stem-resistant), and Denali and Reeder (hollow-stem-susceptible) were infested with WSS, and changes in stem proteins and metabolites were characterized using liquid chromatography-mass spectrometry. The proteome was characterized as 1830 proteins that included five major biological processes, including metabolic processes and response to stimuli, and the metabolome (1823 metabolites) spanned eight chemical superclasses, including alkaloids, benzenoids, and lipids. All four varieties had a molecular response to WSS following infestation. Hatcher had the most distinct changes, whereby 62 proteins and 29 metabolites varied in metabolic pathways involving enzymatic detoxification, proteinase inhibition, and antiherbivory compound production via benzoxazinoids, neolignans, and phenolics. Taken together, these data demonstrate variation in the wheat stem molecular response to WSS infestation and support breeding for molecular resistance in hollow-stem cultivars.

White matter lesions suggestive of amyotrophic lateral sclerosis attributed to celiac disease

CD is an autoimmune-mediated disorder of the gastrointestinal tract. Initial symptom presentation is variable and can include neurologic manifestations that may comprise ataxia, neuropathy, dizziness, epilepsy, and cortical calcifications rather than gastrointestinal-hindering diagnosis and management. We present a case of a young man with progressive neurologic symptoms and brain MR imaging findings worrisome for ALS. During the diagnostic work-up, endomysium antibodies were discovered, and CD was confirmed by upper gastrointestinal endoscopy with duodenal biopsies. MR imaging findings suggestive of ALS improved after gluten-free diet institution.

Installation of the 1.5 T MRI accelerator next to clinical accelerators: impact of the fringe field

In the UMC Utrecht a prototype MRI accelerator has been installed to investigate the feasibility of real-time, MRI guided radiotherapy. The system consists of a 6 MV Elekta (Crawley, UK) accelerator and a 1.5 T Philips (Best, The Netherlands) MRI system. The system is installed in a standard radiotherapy bunker. The bunker is at the corner of a block of six bunkers, so there are three neighbouring clinical Elekta accelerators. During ramping of the magnet, the magnetic fringe field in the two nearest bunkers was measured as a function of the magnetic field strength of the MRI magnet. At 8 m, a maximum increase of 1.5 G was measured, at 12 m, 0.6 G. This is up to three times the earth's magnetic field. The clinical accelerators are needed to be re-calibrated in order to operate in such an external magnetic field. The resulting radiation field flatness of the clinical accelerators was measured and was similar to the situation before ramping the magnet.

Integrating a 1.5 T MRI scanner with a 6 MV accelerator: proof of concept

At the UMC Utrecht, The Netherlands, we have constructed a prototype MRI accelerator. The prototype is a modified 6 MV Elekta (Crawley, UK) accelerator next to a modified 1.5 T Philips Achieva (Best, The Netherlands) MRI system. From the initial design onwards, modifications to both systems were aimed to yield simultaneous and unhampered operation of the MRI and the accelerator. Indeed, the simultaneous operation is shown by performing diagnostic quality 1.5 T MRI with the radiation beam on. No degradation of the performance of either system was found. The integrated 1.5 T MRI system and radiotherapy accelerator allow simultaneous irradiation and MR imaging. The full diagnostic imaging capacities of the MRI can be used; dedicated sequences for MRI-guided radiotherapy treatments will be developed. This proof of concept opens the door towards a clinical prototype to start testing MRI-guided radiation therapy (MRIgRT) in the clinic.

Integrating a 1.5 T MRI scanner with a 6 MV accelerator: proof of concept

At the UMC Utrecht, The Netherlands, we have constructed a prototype MRI accelerator. The prototype is a modified 6 MV Elekta (Crawley, UK) accelerator next to a modified 1.5 T Philips Achieva (Best, The Netherlands) MRI system. From the initial design onwards, modifications to both systems were aimed to yield simultaneous and unhampered operation of the MRI and the accelerator. Indeed, the simultaneous operation is shown by performing diagnostic quality 1.5 T MRI with the radiation beam on. No degradation of the performance of either system was found. The integrated 1.5 T MRI system and radiotherapy accelerator allow simultaneous irradiation and MR imaging. The full diagnostic imaging capacities of the MRI can be used; dedicated sequences for MRI-guided radiotherapy treatments will be developed. This proof of concept opens the door towards a clinical prototype to start testing MRI-guided radiation therapy (MRIgRT) in the clinic.

Natural and anthropogenic geochemical signatures of floodplain and deltaic sedimentary strata, Sacramento-San Joaquin Delta, California, USA

The geochemical history of an upper deltaic plain pending tidal wetland restoration was reconstructed to assess remobilization of redox-sensitive constituents in sediment, identify depositional processes promoting geochemical retention, and determine the extent of contamination with Hg, As, Pb, Cu, and Zn. Three 12-14-m sediment cores were analyzed for bulk sediment geochemistry using ICP-AES. Rather than showing similar stratigraphic and geochemical down-core trends, cores had a unique record indicative of strong spatial gradients in deposition processes. Each strata type (e.g. basal clay, sand channel, distal floodplain, and agriculturally impacted surficial horizon) had a unique geochemical "fingerprint". The agriculturally impacted surficial layer showed high [Hg], [As], and [Pb]. The significance is that a restored upper delta will have a complex geomorphology defying conventional criteria of "success" in a restoration framework. Also, there is a significant risk of generating toxic, bio-available CH3Hg+ that would be hazardous to fish.

Fire cycles in North American interior grasslands and their relation to prairie drought

High-resolution analyses of a late Holocene core from Kettle Lake in North Dakota reveal coeval fluctuations in loss-on-ignition carbonate content, percentage of grass pollen, and charcoal flux. These oscillations are indicative of climate-fuel-fire cycles that have prevailed on the Northern Great Plains (NGP) for most of the late Holocene. High charcoal flux occurred during past moist intervals when grass cover was extensive and fuel loads were high, whereas reduced charcoal flux characterized the intervening droughts when grass cover, and hence fuel loads, decreased, illustrating that fire is not a universal feature of the NGP through time but oscillates with climate. Spectral and wavelet analyses reveal that the cycles have a periodicity of approximately = 160 yr, although secular trends in the cycles are difficult to identify for the entire Holocene because the periodicity in the early Holocene ranged between 80 and 160 yr. Although the cycles are evident for most of the last 4,500 yr, their occasional muting adds further to the overall climatic complexity of the plains. These findings clearly show that the continental interior of North America has experienced short-term climatic cycles accompanied by a marked landscape response for several millennia, regularly alternating between dual landscape modes. The documentation of cycles of similar duration at other sites in the NGP, western North America, and Greenland suggests some degree of regional coherence to climatic forcing. Accordingly, the effects of global warming from increasing greenhouse gases will be superimposed on this natural variability of drought.

Eyestalk ablation has little effect on actin and myosin heavy chain gene expression in adult lobster skeletal muscles

The organization of skeletal muscles in decapod crustaceans is significantly altered during molting and development. Prior to molting, the claw muscles atrophy dramatically, facilitating their removal from the base of the claw. During development, lobster claw muscles exhibit fiber switching over several molt cycles. Such processes may be influenced by the secretion of steroid molting hormones, known collectively as ecdysteroids. To assay the effects of these hormones, we used eyestalk ablation to trigger an elevation of circulating ecdysteroids and then quantified myofibrillar mRNA levels with real-time PCR and myofibrillar protein levels by SDS-PAGE. Levels of myosin heavy chain (MHC) and actin proteins and the mRNA encoding them were largely unaffected by eyestalk ablation, but in muscles from intact animals, myofibrillar gene expression was modestly elevated in premolt and postmolt animals. In contrast, polyubiquitin mRNA was significantly elevated (about 2-fold) in claw muscles from eyestalk-ablated animals with elevated circulating ecdysteroids. Moreover, patterns of MHC and actin gene expression are significantly different among slow and fast claw muscles. Consistent with these patterns, the three muscle types differed in the relative amounts of myosin heavy chain and actin proteins. All three muscles also co-expressed fast and slow myosin isoforms, even in fibers that are generally regarded as exclusively fast or slow. These results are consistent with other recent data demonstrating co-expression of myosin isoforms in lobster muscles.

Target and non-target ERP disturbances in first episode vs. chronic schizophrenia

OBJECTIVES

Event-related potential (ERP) abnormalities to target stimuli are reliably found in schizophrenia. However, as people with schizophrenia are thought to have difficulty discerning the relevance of incoming sensory stimuli it is also important to examine ERPs to non-targets. To differentiate between potential trait markers of the disease and deficits that might be associated with the consequence of illness chronicity, this study investigated ERPs to both target and non-target stimuli in groups of people with either first episode or chronic schizophrenia (CSz).

METHODS

Using an auditory oddball paradigm, ERPs to target, non-target before target (Nt before) and non-target after target (Nt after) stimuli were analysed for 40 patients with CSz, 40 patients with first episode schizophrenia (FESz) and two groups of normal controls matched for age and sex with their patient counterparts.

RESULTS

The FESz group showed the same pattern of amplitude disturbance as the CSz group to both targets (reduced N100, N200, P300 and increased P200) and non-targets (reduced N100) compared to controls. Both CSz and FESz groups also failed to show the changes to the P200-N200 component between targets and non-target stimuli that was exhibited by controls (smaller earlier P200 to targets vs. increased delayed P200 to non-targets) or the reduction in N100 amplitude of ERPs to the Nt after stimuli compared with ERPs to the Nt before stimuli. Previous literature has focussed on the sensitivity of P300 deficits in classifying persons into schizophrenia and non-schizophrenia groups. This study demonstrated improved accuracy in the classification of patients with schizophrenia from controls using discriminant analysis of target and non-target N100 and P200 components.

CONCLUSIONS

The results suggest that ERP disturbances are evident at the time of first referral to mental health services and may be a potential trait (rather than secondary effect) of the illness. It is important to include both target and non-target stimuli processing, and their interrelationship in future research.

Responses of leaf respiration to temperature and leaf characteristics in three deciduous tree species vary with site water availability

We measured responses of leaf respiration to temperature and leaf characteristics in three deciduous tree species (Quercus rubra L., Quercus prinus L. and Acer rubrum L.) at two sites differing in water availability within a single catchment in the Black Rock Forest, New York. The response of respiration to temperature differed significantly among the species. Acer rubrum displayed the smallest increase in respiration with increasing temperature. Corresponding Q(10) values ranged from 1.5 in A. rubrum to 2.1 in Q. prinus. Dark respiration at ambient air temperatures, expressed on a leaf area basis (Rarea), did not differ significantly between species, but it was significantly lower (P < 0.01) in trees at the wetter (lower) site than at the drier (upper) site (Q. rubra: 0.8 versus 1.1 micromol m(-2) s(-1); Q. prinus: 0.95 versus 1.2 micromol m(-2) s(-1)). In contrast, when expressed on a leaf mass basis (R(mass)), respiration rates were significantly higher (P < 0.01) in A. rubrum (12.5-14.6 micromol CO(2) kg(-1) s(-1)) than in Q. rubra (8.6-9.9 micromol CO(2) kg(-1) s(-1)) and Q. prinus (9.2-10.6 micromol CO(2) kg(-1) s(-1)) at both the lower and upper sites. Respiration on a nitrogen basis (R(N)) displayed a similar response to R(mass). The consistency in R(mass) and R(N) between sites indicates a strong coupling between factors influencing respiration and those affecting leaf characteristics. Finally, the relationships between dark respiration and A(max) differed between sites. Trees at the upper site had higher rates of leaf respiration and lower A(max) than trees at the lower site. This shift in the balance of carbon gain and loss clearly limits carbon acquisition by trees at sites of low water availability, particularly in the case of A. rubrum.

beta(1)- and beta(3)-adrenoceptor mediated smooth muscle relaxation in hypothyroid rat ileum

The effect of hypothyroidism on gastrointestinal beta(1)- and beta(3)-adrenoceptor function and expression was examined in rat ileal smooth muscle preparations. (-)-Isoprenaline and the selective beta(3) agonist disodium (R,R)-5-[2-[[2-3-chlorophenyl)-2-hydroxyethyl]-amino]propyl]-1,3-benzodioxole-2,2-dicarboxylate (CL 316234) relaxed both control and hypothyroid tissues in a dose-dependent manner. Responses to isoprenaline were reduced in tissues from hypothyroid rats, as was the shift produced with the beta(3)-adrenoceptor antagonist, 3-(2-ethylphenoxy)-1-[(1S)-1,2,3,4-tetrahydronaphth-1-ylamino]-(2S)-2-propanol oxalate (SR 59230A). No change was seen in responses to CL 316243. Experiments with a selective beta(1)-adrenoceptor antagonist produced results suggesting that isoprenaline did not act at this receptor. Messenger RNA levels for both beta(1)- and beta(2)-adrenoceptors were not affected by hypothyroidism. These results show that, unlike in adipose tissues, ileal beta(1)- and beta(3)-adrenoceptors are not directly regulated by thyroid hormone and that beta(3)-adrenoceptor coupling to the relaxation response is reduced in a rat model of hypothyroidism.

Requirements for leaf position accuracy for dynamic multileaf collimation

Intensity modulated radiation therapy can be achieved by driving the leaves of a multileaf collimator (MLC) across an x-ray therapy beam. Algorithms to generate the required leaf trajectories assume that the leaf positions are exactly known to the MLC controller. In practice, leaf positions depend upon calibration accuracy and stability and may vary within set tolerances. The purpose of this study was to determine the effects of potential leaf position inaccuracies on intensity modulated beams. Equations are derived which quantify the absolute error in delivered monitor units given a known error in leaf position. The equations have been verified by ionization chamber measurements in dynamically delivered flat fields, comparing deliveries in which known displacements have been applied to the defined leaf positions with deliveries without displacements applied. The equations are then applied to two clinical intensity modulations: an inverse planned prostate field and a breast compensating field. It is shown that leaf position accuracy is more critical for a highly modulated low-dose intensity profile than a moderately modulated high-dose intensity profile. Suggestions are given regarding the implications for quality control of dynamic MLC treatments.

Identification of sulfated oligosaccharide-based inhibitors of tumor growth and metastasis using novel in vitro assays for angiogenesis and heparanase activity

Inhibitors of tumor angiogenesis and metastasis are rapidly emerging as important new drug candidates for cancer therapy. To facilitate the identification of such drugs, we recently developed novel and rapid in vitro assays for human angiogenesis and for the extracellular matrix-degrading enzyme heparanase, which has been implicated in tumor metastasis. In this study, sulfated oligosaccharides, which are structural mimics of heparan sulfate, were investigated as drug candidates because these compounds may interfere with heparan sulfate recognition by many angiogenic growth factors and may inhibit cleavage of heparan sulfate by heparanase. In the preliminary screening studies, it was found that inhibitory activity in both assay systems was critically dependent on chain length and degree of sulfation, highly sulfated linear oligosaccharides of five or more monosaccharides in length being the most active. However, two sulfated oligosaccharides stood out as potential antitumor drugs, phosphomannopentaose sulfate (PI-88) and maltohexaose sulfate, both of these compounds having the important property of simultaneously being potent inhibitors of in vitro angiogenesis and heparanase activity. Due to the ease of manufacture of the starting material, phosphomannopentaose, PI-88 was studied in more detail. PI-88 was shown to inhibit the primary tumor growth of the highly invasive rat mammary adenocarcinoma 13762 MAT by approximately 50%, inhibit metastasis to the draining popliteal lymph node by approximately 40%, and reduce the vascularity of tumors by approximately 30%, all of these effects being highly significant. Acute hematogenous metastasis assays also demonstrated that PI-88 was a potent (>90%) inhibitor of blood-borne metastasis. Thus, by the use of novel in vitro screening procedures, we have identified a promising antitumor agent.

Alcohol preference and sensitivity are markedly reduced in mice lacking dopamine D2 receptors

Although dopaminergic transmission has been strongly implicated in alcohol self-administration, the involvement of specific dopamine receptor subtypes has not been well established. We studied the ethanol preference and sensitivity of D2-receptor-deficient mice to directly evaluate whether dopamine D2 receptors contribute to alcohol (ethanol) consumption. We report a marked aversion to ethanol in these mice, relative to the high preference and consumption exhibited by wild-type littermates. Sensitivity to ethanol-induced locomotor impairment was also reduced in these mutant mice, although they showed a normal locomotor depressant response to the dopamine D1 antagonist SCH-23390. These data demonstrate that dopamine signaling via D2 receptors is an essential component of the molecular pathway determining ethanol self-administration and sensitivity.

Correlates of in-hospital cost among patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Surgical repair of abdominal aortic aneurysms (AAA) is increasingly being performed, but little is known about the correlates of in-hospital cost associated with this procedure.

METHODS AND RESULTS

Baseline clinical characteristics, in-hospital outcomes, and total in-hospital costs were examined among a retrospective cohort of 71 patients who underwent AAA repair. Median age was 68 years, and 75% of the patients were men. High-risk characteristics for perioperative complications were common and included hypertension (73%), documented coronary artery disease (66%), smoking (60%), previous myocardial infarction (47%), history of congestive heart failure (12%), urgent or emergent AAA repair (16%), and diabetes mellitus (11%). Perioperative complications included congestive heart failure (13%), myocardial infarction (11 %), and death (1 %). Median length of stay in the surgical intensive care unit (SICU) was 2 days (range 0 to 28), and median in-hospital stay was 9 days (range 5 to 39). In-hospital cost for the 71 patients ranged from $13,766 to $82,435 (mean $25,931, median $21,633). Univariate and multiple linear regression analyses demonstrated that among the potential correlates investigated, number of SICU days (P= .007) and total length of stay (P< .0001) were the most closely associated with in-hospital cost.

CONCLUSIONS

Among patients undergoing AAA repair, the major correlates of in-hospital cost are the number of days spent in the SICU and the total number of days spent in the hospital. These results suggest that any intervention that reduces length of stay may significantly reduce the total in-hospital cost associated with AAA repair.

In vitro biological characterization and antiangiogenic effects of PD 166866, a selective inhibitor of the FGF-1 receptor tyrosine kinase

Through direct synthetic efforts, we discovered a small molecule that is a nanomolar inhibitor of the human fibroblast growth factor-1 receptor (FGFR) tyrosine kinase. PD 166866, a member of a new structural class of tyrosine kinase inhibitors, the 6-aryl-pyrido[2,3-d]pyrimidines, was identified by screening a compound library with assays that measure protein tyrosine kinase activity. PD 166866 inhibited human full-length FGFR-1 tyrosine kinase with an IC50 value of 52.4 +/- 0.1 nM and was further characterized as an ATP competitive inhibitor of the FGFR-1. In contrast, PD 166866 had no effect on c-Src, platelet-derived growth factor receptor-beta, epidermal growth factor receptor or insulin receptor tyrosine kinases or on mitogen-activated protein kinase, protein kinase C and CDK4 at concentrations as high as 50 microM. PD 166866 was a potent inhibitor of basic fibroblast growth factor (bFGF)-mediated receptor autophosphorylation in NIH 3T3 cells expressing endogenous FGFR-1 and in L6 cells overexpressing the human FGFR-1 tyrosine kinase, confirming a tyrosine kinase-mediated mechanism. PD 166866 also inhibited bFGF-induced tyrosine phosphorylation of the 44- and 42-kDa (ERK 1/2) mitogen-activated protein kinase isoforms in L6 cells, presumably via inhibition of bFGF-stimulated FGFR-1 tyrosine kinase activation. PD 166866 did not inhibit platelet-derived growth factor, epidermal growth factor or insulin-stimulated receptor autophosphorylation in vascular smooth muscle, A431 or NIHIR cells, respectively, further supporting its specificity for the FGFR-1. In addition, daily exposure of PD 166866 to L6 cells at concentrations from 1 to 100 nM resulted in a concentration-related inhibition of bFGF-stimulated cell growth for 8 consecutive days with an IC50 value of 24 nM. In contrast, PD 166866 had little effect on platelet-derived growth factor-BB-stimulated growth of L6 cells or serum-stimulated vascular smooth muscle cell proliferation. Finally, PD 166866 was found to be a potent inhibitor of microvessel outgrowth (angiogenesis) from cultured artery fragments of human placenta. These results highlight the discovery of PD 166866, a new nanomolar potent and selective small molecule inhibitor of the FGFR-1 tyrosine kinase with potential use as antiproliferative/antiangiogenic agent for such therapeutic targets as tumor growth and neovascularization of atherosclerotic plaques.

Cost of cardiac care in the three years after coronary catheterization in a contained care system: critical determinants and implications

OBJECTIVES

We sought to determine the clinical, angiographic, treatment and outcome correlates of the intermediate-term cost of caring for patients with suspected coronary artery disease (CAD).

BACKGROUND

To adequately predict medical costs and to compare different treatment and cost reduction strategies, the determinants of cost must be understood. However, little is known about the correlates of costs of treatment of CAD in heterogeneous patient populations that typify clinical practice.

METHODS

From a consecutive series of 781 patients undergoing cardiac catheterization in 1992 to 1994, we analyzed 44 variables as potential correlates of total (direct and indirect) in-hospital, 12- and 36-month cardiac costs.

RESULTS

Mean (+/-SD) patient age was 65+/-10 years; 71% were men, and 45% had multiple vessel disease. The initial treatment strategy was medical therapy alone in 47% of patients, percutaneous intervention (PI) in 30% and coronary artery bypass graft surgery (CABG) in 24%. The 36-month survival and event-free (death, infarction, CABG, PI) survival rates were 89.6+/-0.2% and 68.4+/-0.4%, respectively. Median hospital and 36-month costs were $8,301 and $28,054, respectively, but the interquartile ranges for both were wide and skewed. Models for log(e) costs were superior to those for actual costs. The variances accounted for by the all-inclusive models of in-hospital, 12- and 36-month costs were 57%, 60% and 71%, respectively. Baseline cardiac variables accounted for 38% of the explained in-hospital costs, whereas in-hospital treatment and complication variables accounted for 53% of the actual costs. Noncardiac variables accounted for only 9% of the explained costs. Over time, complications (e.g., late hospital admission, PI, CABG) and drug use to prevent complications of heart transplantation became more important, but many baseline cardiac variables retained their importance.

CONCLUSIONS

1) Variables readily available from a comprehensive cardiovascular database explained 57% to 71% of cardiac costs from a hospital perspective over 3 years of care; 2) the initial revascularization strategy was a key determinant of in-hospital costs, but over 3 years, the initial treatment become somewhat less important, and late complications became more important determinants of costs.

Effects of ddC and AZT on locomotion and acoustic startle. I: Acute effects in female rats

Several synthetic nucleoside analogues, including AZT(RETROVIR), ddC (HIVID), ddI (VIDEX), and d4T (ZERIT), are currently being used in the treatment of HIV infection. Unfortunately, in clinical use the appearance of severe and sometimes debilitating peripheral neuropathy and pain has been associated with the long-term use of several of these drugs (i.e., ddC, ddI and d4T), although not with AZT. To date, standard pre-clinical animal toxicity studies have failed to reveal any adverse neurologic effects of these compounds. However, previously reported preliminary findings suggest that ddC may alter several neuro-behavioral parameters (including locomotor activity, acoustic startle responding, and aggression) in rats and mice following presentation in the animals' drinking water for 7 days. The current series of experiments examined effects of acutely administered ddC and AZT on spontaneous locomotor activity and acoustic startle responses (with and without pre-pulse) in female Sprague-Dawley rats. Following intragastric administration, ddC reduced locomotion at all but the highest dose, whereas AZT had no significant effect on locomotor activity. Acutely administered ddC had no effect on ASR, whereas AZT increased ASR at the highest stimulus intensity. These data support the use of behavioral testing in the development of the antiviral nucleoside analogues, as behavioral testing may be more effective in identifying the neurologically active agents than is standard toxicity testing.

Echocardiographic score as a predictor of in-hospital cost in patients undergoing percutaneous balloon mitral valvuloplasty

Percutaneous balloon mitral valvuloplasty (PBMV) is an effective means of palliating mitral stenosis, but it sometimes leads to adverse clinical outcomes and exorbitant in-hospital costs. Because echocardiographic score is known to be predictive of clinical outcome in patients undergoing PBMV, we examined whether it could also be used to predict in-hospital cost. Preprocedure echocardiographic scores, baseline clinical characteristics, and total in-hospital costs were examined among 45 patients who underwent PBMV between January 1, 1992, and January 1, 1994. Patients ranged in age from 18 to 71 years and had preprocedure echocardiographic scores that ranged from 4 to 12. Following PBMV, mean mitral valve area increased from 1.1 +/- 0.3 to 2.4 +/- 0.6 cm2 (p = 0.0001), and mean pressure gradient decreased from 18.3 +/- 5.9 to 6.7 +/- 2.7 mm Hg (p = 0.0001). In-hospital cost for the 45 patients ranged from $3,591 to $70,975 (mean $9,417; median $5,311). Univariate and multiple linear regression analyses demonstrated that among the variables examined, echocardiographic score (p = 0.0007), age (p = 0.01), and preprocedure mitral valve gradient (p = 0.03) were associated with in-hospital cost. Regression modeling suggested that every increase in preprocedure echocardiographic score of one grade was associated with an increase in in-hospital cost of $2,663. Because echocardiographic score is predictive of both clinical outcome and in-hospital cost, we conclude that patients with elevated scores should be considered for alternative therapy.

A novel in vitro assay for human angiogenesis

Angiogenesis, the development of new blood vessels, is an important process in tissue development and wound healing but becomes pathologic when associated with solid tumor growth, proliferative retinopathies, and rheumatoid arthritis. To date, there has not been a physiologically relevant in vitro model for human angiogenesis that can be used to screen for enhancers and inhibitors of human angiogenesis and allow further investigation of this process. Initially, culture conditions were established for the induction of human angiogenesis in vitro using fragments of human placental blood vessel. Once the assay was validated, it was examined for its ability to detect known inhibitors and enhancers of angiogenesis. The role of endogenous acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) in the angiogenic response was also assessed by performing RT-PCR on both the parent vessel and microvessel outgrowths. In addition, neutralizing antibodies against the three growth factors were used to quantify the relative importance of each growth factor in the angiogenic response. A fragment of human placental blood vessel was embedded in a fibrin gel in microculture plates and was found to give rise to a complex network of microvessels during a period of 7 to 21 days in culture. The response did not require the addition of exogenous growth factors, and thus provides a convenient system for testing substances for their ability to stimulate or inhibit a human in vitro angiogenic response. The ability of the well known angiogenesis antagonist, hydrocortisone, in the presence and absence of heparin, and suramin to significantly inhibit the angiogenic response indicated that the model could be used as an efficient in vitro assay for screening inhibitors of human angiogenesis. The presence of mRNA for aFGF, bFGF, and three isoforms of VEGF, as well as their receptors, FGFR1, FGFR2, Flt-1, and KDR, in vessel outgrowths and the parent vessel, as identified by RT-PCR, strongly implicated aFGF, bFGF, and VEGF as having an important role in this neovascularization response. This was further confirmed by the ability of neutralizing antibodies to aFGF, bFGF, and VEGF to inhibit the angiogenic response to varying extent. Furthermore, the response could be enhanced by the addition of these growth factors in serum-starved cultures. Finally, a stimulatory effect was observed when matrigel was incorporated into the fibrin gel, which indicates that components of the extracellular matrix also play an important role in governing the strength of the angiogenic response. A physiologic angiogenic response relevant to wound healing can be generated by culturing fragments of human placental blood vessels in fibrin gels. The growth factors aFGF, bFGF, and VEGF were shown to play an important role in stimulating this spontaneous angiogenic response. This assay, which can be performed in microcultures, was also shown to be an excellent method for screening for potential inhibitors and enhancers of human angiogenesis.

Effects of environmental conditions on food consumption in female and male rats

The present experiment examined food and water consumption under different housing conditions in 20 female and 20 male Wistar rats. Food and water consumption were measured for 6 h a day following an 18-h same-sex crowded or individual housing period for each of 6 days. All subjects were individually housed during the 6-h measurement period and had access to food and water. Female rats consumed more food and water than did male rats during the 6-h period, regardless of their 18-h housing condition. In addition, previously crowded rats consumed more food and water during the 6-h period than did rats that were previously individually housed. During the 18-h period, when subjects were differentially housed, males consumed more food and water than did females; crowded rats ate less than did individually housed rats; and crowded rats drank more water than did individually housed rats. Based on plasma corticosterone data, the female and male rats were differentially affected by housing conditions. The present results are discussed with regard to housing conditions per se and sex differences in stress responses to housing.

Cost-efficacy modeling of catheter reuse for percutaneous transluminal coronary angioplasty

OBJECTIVES

Our goal was to provide the range of cost savings associated with various catheter reuse strategies.

BACKGROUND

Percutaneous transluminal coronary angioplasty catheters are commonly reused in several countries outside the United States. However, the cost-effectiveness of such reuse strategies has not been evaluated.

METHODS

Three theoretical models of catheter reuse were constructed using the actual costs for treating patients with coronary angioplasty at the Cleveland Clinic. Costs were calculated based on the number of balloon catheters, the amount of contrast agent used and the rates for urgent revascularization that were observed in a prospective Canadian study on catheter reuse.

RESULTS

The median cost to treat a lesion by means of coronary angioplasty using new catheters was $8,800 per patient. In reuse models, the potential to reduce cost depended on the number of balloon catheters used and the rates of urgent revascularization. The "best care" scenario offered a potential savings of $480 (5.5% of total in-hospital cost), whereas the "worst case" scenario resulted in an increased cost of $1,075 (12.2% of total in-hospital cost) compared with the single-use strategy. Cost of the "likely case" scenario was similar to that of the single-use strategy. Sensitivity analyses identified the different rates of revascularization and cost of balloon catheters required to offset potential savings in each strategy.

CONCLUSIONS

Although reusing coronary angioplasty catheters may reduce total in-hospital costs, even a modest increase in complications requiring urgent revascularization may offset any potential savings. However, if an increase in complications and procedure time can be avoided, the reuse strategy has significant economic potential and, ultimately, may be extended to other percutaneous coronary interventional equipment.

Vascular anatomy of experimentally induced left varicocele in the rat

A variety of techniques have been used by various investigators to study the effects of experimentally induced left varicocele in the rat model. It has become apparent that information about the vascular anatomy of this condition in the rat is deficient, though such information could be important to understanding the model. We have examined the left and right venous architecture serving the testes in rats with and without experimentally induced left varicocele. The left spermatic vein has four consistent collaterals that are tributary to the left iliac vein. The right spermatic vein does not have these consistent collaterals, but many times a collateral develops from the right spermatic vein to either the right iliac vein or the distal part of the caudal vena cava. When this occurs, the remaining length of the right spermatic vein becomes a minor effluent vessel. Eleven irregularly observed vessels were identified, none of which existed on the left and only two of which were observed on the right. Experimentally induced left varicocele is associated with dilatation of the left spermatic vein and all collaterals to the left iliac vein. The condition does not cause dilatation of the right venous system, but one collateral was identified that communicated between the left and right sides via the vesicular plexus. It is speculated that the differences between left and right sides in the number of consistent collaterals might be due to the patterns of embryologic development, which differ somewhat between the left and right spermatic veins.

Outmigration for coronary bypass surgery in an era of public dissemination of clinical outcomes

BACKGROUND

Since 1989, New York State has disseminated comparative information on outcomes of coronary bypass surgery to the public. It has been suggested that this program played a significant role in the 41% decrease in the risk-adjusted mortality rate between 1989 and 1992. We hypothesized that some high-risk patients had migrated out of state for surgery.

METHODS AND RESULTS

We reviewed 9442 isolated coronary bypass operations performed from 1989 through 1993 to assess referral patterns of case-mix and outcome. Expected and risk-adjusted mortality rates were computed using logistic regression models derived from the Cleveland Clinic and New York State databases. A mortality comparison was performed using the 1980 to 1988 time period as a historical control. Patients from New York (n=482) had a higher frequency of prior open heart surgery (44.0%) than patients from Ohio (n=6046) (21.5%, P<.001), other states (n=1923) (37.4%, P=.008), and other countries (n=991) (17.3%, P<.001). They were also more likely to be in NYHA functional class III or IV (47.6% versus Ohio 42.7%, P=.037; other states, 41.2%, P=.011; other countries, 34.1%, P=.001). The expected mortality rate was thus higher than among other referral cohorts. The observed 5.2% mortality rate among these patients was significantly greater than the 2.9%, 3.1%, and 1.4% mortality rates observed for patients from Ohio (P=.004), other states (P=.028), and other countries (P<.001). These differences in outcome were not apparent between 1980 and 1988 among referrals from within the United States.

CONCLUSIONS

Public dissemination of outcome data may have been associated with increased referral of high-risk patients from New York to an out-of-state regional medical center.

Effects of housing on male and female rats: crowding stresses male but calm females

Housing conditions affect behavioral and biological responses of animals. Effects of same-sex grouped, crowded, or individually housed conditions on plasma corticosterone levels of male and female Wistar rats were examined in two experiments. Experiment 1 examined the effects of individual vs. crowded housing conditions on corticosterone, a biochemical index of stress, in seven male and seven female rats. Experiment 2 extended the findings of Experiment 1 by separately manipulating spatial and population aspects of housing with 50 male and 50 female rats. Male rats had higher corticosterone levels under crowded conditions. In contrast, female rats had higher levels when individually housed. Spatial crowding was the key variable for males, whereas the number of other animals was more important for females. These results indicate that investigators must consider housing conditions as an intervening variable that is likely to differentially affect behaviors of male and female rats.

In-hospital cost of percutaneous coronary revascularization. Critical determinants and implications

BACKGROUND

Hospital charges associated with percutaneous transluminal coronary revascularization (PTCR) in the United States exceeded $6 billion in 1994 and are likely to be constrained in some manner in the near future. Despite this high cost to the public, little is known about the major determinants and sources of variability of PTCR.

METHODS AND RESULTS

From a consecutive series of 1258 procedures with attempted PTCR at a single tertiary referral center, we analyzed 65 clinical, angiographic, physician, and outcome variables as potential correlates of total (hospital and physician) cost. Direct and indirect costs, both hospital and physician, were determined on the basis of resource utilization using "top-down" methodology and were available for 1237 procedures (1086 patients) (98.3%). Mean (+/- SD) patient age was 62 +/- 11 years, 76% were male, 3% had acute myocardial infarction, 71% had unstable angina, 58% had multivessel disease, left ventricular ejection fraction was 54 +/- 12%, 26% had use of at least one nonballoon revascularization device, and median length of stay was 4.4 days. Procedural success was obtained in 89%, and major complications (death, bypass surgery, or Q-wave myocardial infarction) occurred in 3.8%. The median cost was $9176, but it was asymmetrically distributed, and the interquartile and total ranges were wide ($7333 to $13,845 and $3422 to $193,474, respectively). Analyses of independent correlates of cost and loge(cost) were performed using multivariate linear regression in training and test populations. Modeling found 15 independent preprocedural correlates of loge(cost) (R2 = .37) and 23 overall correlates (R2 = .65), excluding length of stay per se. Additional of length of stay to the model increased the explanatory power of the model to R2 = .82. Preprocedural variables most predictive of loge(cost) included presentation with acute myocardial infarction, decision delay (> 48 hours between admission and diagnostic angiography and/or > 24 hours between angiography and intervention), weekend delay, use of intra-aortic balloon counterpulsation, intention to stent, creatinine > or = 2.0 mg%, and lesion complexity (modified American College of Cardiology/American Heart Association score) (all P < .001). In the model that included postprocedural variables as well, length of stay, noncardiac death, urgent bypass surgery, use of the Rotablator, Q-wave myocardial infarction, rise in creatinine > or = 1.0%, and blood product transfusion were all strong independent correlates of loge(cost) (P < .001).

CONCLUSIONS

The range of total hospital costs associated with percutaneous intervention is extraordinarily wide. Baseline patient characteristics account for nearly half of the explained variance, but procedural complications and system delays account for much of the remainder. Quantification of the determinants of cost may promote more economically efficient care in the future.

Acidic and basic fibroblast growth factor bind with differing affinity to the same heparan sulfate proteoglycan on BALB/c 3T3 cells: implications for potentiation of growth factor action by heparin

Heparan sulfate proteoglycans on the cell surface act as low affinity binding sites for acidic and basic fibroblast growth factor (FGF) [Moscatelli (1987): J Cell Physiol 131:123-130] and play an important role in the interaction of FGF with the FGF receptor (FGFR). In this study, several aspects of the interaction of FGFs with cell surface heparan sulfate proteoglycans were examined. Reciprocal cross blocking studies demonstrated that acidic FGF (aFGF) and basic FGF (bFGF) bind to identical or closely associated heparan sulfate motifs on BALB/c 3T3 cell surface heparan sulfate proteoglycans. However, the binding affinity of the two growth factors for these heparan sulfate proteoglycans differs considerably, competition binding data indicating that aFGF has a 4.7-fold lower affinity than bFGF for 3T3 heparan sulfate proteoglycan. Subsequent studies of dissociation kinetics demonstrated that bFGF dissociates from the FGFR at least 10-fold slower than aFGF, whereas, following removal of cell surface heparan sulfate proteoglycans by heparinase treatment, the dissociation rate of both FGFs is similar and rapid. These results support the concept that cell surface heparan sulfate proteoglycans stabilize the interaction of FGF with FGFR, possibly by the formation of a ternary complex.

Evidence that carboxyl-reduced heparin fails to potentiate acidic fibroblast growth factor activity due to an inability to interact with cell surface heparin receptors

Recently we reported that carboxyl-reduced heparin (CR-heparin), despite binding acidic fibroblast growth factor (aFGF) as effectively as native heparin, was much less potent at augmenting aFGF-induced mitogenesis. This paper describes experiments which examined this phenomenon in more detail in the hope that it would shed light on the mechanism by which heparin potentiates aFGF activity. Initial studies confirmed that heparin, with 60% of its carboxyl groups reduced, although binding aFGF with the same affinity as native heparin (Kd 35 +/- 5 nM), was a poor potentiator of aFGF-induced mitogenic activity. Proteolysis protection experiments also revealed that CR-heparin was as effective as native heparin at protecting aFGF from proteolytic degradation. In contrast, CR-heparin was considerably less effective than native heparin at enhancing the binding of aFGF to the fibroblast growth factor receptor (FGFR) on 3T3 cells. Furthermore, CR-heparin only bound to a subset (approximately 1/3) of heparin receptors on 3T3 cells. Based on these data, it is proposed that CR-heparin is less efficient than heparin at facilitating the formation of a quaternary complex among aFGF, the FGFR, and cell surface heparin receptors.

Strain and age differences in acoustic startle responses and effects of nicotine in rats

Two experiments examined the effects of age, genetic strain, and nicotine on acoustic startle response (ASR) amplitude and prepulse inhibition (PPI) in rats. ASR amplitude measures reactivity to external stimulation, and PPI is used as an index of sensory gating related to attention. Both ASR amplitude and PPI have been previously reported to be increased by nicotine in adult rats. Experiment 1 examined effects of chronically administered nicotine and saline on ASR and PPI in Wistar, Long-Evans, and Sprague-Dawley rats (40 days of age). Experiment 2 examined the effects of chronically administered nicotine and saline in Sprague-Dawley rats of two age groups: 40 and 70 days of age at the beginning of the study. ASR amplitude differed significantly across strains with the values for Wistar > Sprague-Dawley > Long-Evans, and there were no differences in percent of PPI among the three strains. In addition, results of Experiment 2 indicated that older rats had significantly greater ASR amplitudes and PPI than younger rats. Consistent with previous reports, nicotine increased ASR and PPI in the older rats; however, there were no significant differences in the younger rats. Therefore, age and genetic strain are important variables in the analysis of nicotine's effects on startle behaviors in rats.

Histidine-rich glycoprotein and platelet factor 4 mask heparan sulfate proteoglycans recognized by acidic and basic fibroblast growth factor

Recent studies have shown that fibroblast growth factors (FGFs) need to interact with cell-surface heparan sulfate proteoglycans (HSPGs) in order to bind to and activate FGF receptors. In this paper, three major heparin-binding proteins, histidine-rich glycoprotein (HRG) and antithrombin III (ATIII), which are constitutively present at high concentrations in plasma, and platelet factor 4 (PF4), which is released locally at high concentrations by degranulating platelets, were tested for their ability to act as modulators of FGF activity by competing with the FGFs for cell-surface HSPGs. HRGs from both chicken and human, and human PF4, were demonstrated to compete with each other and with acidic FGF (aFGF) and basic FGF (bFGF) for binding to BALB/c 3T3 cell-surface HSPGs, whereas ATIII did not compete. Thus, HRG, PF4, aFGF, and bFGF all interact with the same HS chains on the 3T3 cell surface, either binding to the same or binding to adjacent saccharide sequences on the chains. In terms of their relative binding affinity for cell-surface HSPGs, the hierarchy was shown to be PF4 > or = bFGF > aFGF = cHRG > hHRG. HRG was also shown to significantly inhibit both FGF-stimulated and endogenous 3T3 cell DNA synthesis. HRG also binds to extracellular matrices (ECM), originating from bovine corneal endothelial cells, in a heparin-inhibitable manner. Indeed, both HRG and PF4, at physiological concentrations, were shown to effectively inhibit the binding of 125I-aFGF and 125I-bFGF to ECM. In addition, HRG was able to displace biologically active bFGF from the ECM. On the basis of these findings, it is proposed that HRG and PF4 may act as positive regulators of FGF activity by displacing FGF from the ECM or basement membrane and making FGF available to responsive cells. Alternatively, they could act as negative regulators by masking HSPGs on responsive cells and preventing FGF receptor activation.

Spermatic cord torsion: loss of spermatogenesis despite return of blood flow

Previous work in animal models has recapitulated and refined the clinical observation that longer periods of testicular torsion are associated within increased damage to the testis. Minimum times of damage-inducing torsion have not been established, however, nor has it been established to what degree blood flow returns to the testis on examination several hours or days after the torsion repair. Adult male rats were subjected to 0.5-h or 1.0-h 720 degrees torsion and examined for effects on testis weight, histology, and daily sperm production (DSP). None of the parameters examined were affected by 0.5-h, but all were affected by 1.0-h torsion. In a subsequent experiment, adult rats were subjected to unilateral, 1-h, 720 degrees torsion, and bilateral testicular blood flow as measured by radiolabeled microsphere distribution was determined during torsion and 4 h, 24 h, 2 days, 7 days, 15 days, and 30 days after repair of torsion. Ipsilateral testicular blood flow was reduced 94% during torsion. Blood flow was not significantly different from control or contralateral values by 4 or 24 h after repair of torsion. In spite of this return of blood flow, testis weights were significantly reduced by half by 7 days after torsion repair and spermatogenesis was clearly disrupted upon histological examination 30 days after torsion repair. Increasing the time of torsion to 2 or 4 h did not inhibit return of blood flow to the testis as measured 48 h after torsion repair. Unless the testis is infarcted, testicular blood flow in the rat model returns to normal after torsion repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Testicular intravascular volume and microvessel mitotic activity: effect of experimental varicocele

Testicular blood flow increases bilaterally in animals with experimental left varicocele (ELV). The present experiments were undertaken to determine if increases in testicular intravascular volume and capillary growth were potential contributors to this increase in flow. Testicular intravascular volume (microliters/g) was estimated by determining testicular vascular 125I-albumin space. Microvessel mitotic activity was estimated by examining 3H-thymidine incorporation into endothelial nuclei, as assayed by silver grain localization over microvessel endothelial nuclei after exposure of testes to 3H-thymidine in vivo. Testicular intravascular volume was 25-30 microliters/g testis in control testes and in ELV animals was increased an average of 9% and 28% in right and left testes, respectively. This increase was statistically significant (P < 0.05) on the left side only. Approximately 1.5-2.0% of testicular microvessel endothelial nuclei exhibited silver grain localization, and ELV was not associated with a change in these values in either right or left testis. Ancillarily, there was a modest but significant association between microvessel mitotic activity and mitotic activity in adjacent seminiferous tubules. It was concluded that bilateral increases in testicular blood flow after ELV are not uniquely the result of bilateral expansion of intravascular volume and growth of the testicular capillaries. It is speculated, however, that mitogenic factors from the seminiferous tubules potentially affect mitotic activity of the adjacent microvasculature.

Molecular cloning and nucleotide sequence determination of the Bacillus stearothermophilus NCA 1503 superoxide dismutase gene and its overexpression in Escherichia coli

The gene (sod) encoding Bacillus stearothermophilus Mn-superoxide dismutase (MnSOD) has been cloned in Escherichia coli and its entire nucleotide sequence determined. With the exception of the post-translationally cleaved N-terminal methionine residue, the predicted amino acid sequence exhibits complete identity to the previously determined amino acid sequence. The recombinant MnSOD was shown to be functionally active in E. coli both in vitro and in vivo, and was expressed to 49% of the soluble cell protein by coupling its transcription to the E. coli trp promoter. The sequenced region of DNA was also found to encompass a second open reading frame. The putative encoded polypeptide exhibited no significant primary sequence homology to any currently characterised protein.

Depression and anxiety among chronically ill heart patients: age differences in risk and predictors

Anxiety and depression for 399 survivors of a 1,102-member heart disease cohort were assessed 8 to 9 years post-hospitalization. Approximately one-third reported symptoms of emotional distress and one-fourth were on anti-anxiety drugs. Predictors of anxiety and depression were analyzed through logistic regression. Subjects age 65 and over were less likely than younger patients to report anxiety or depression and also reported less heart-associated disability, the strongest predictor of distress for both age groups. Other significant predictors included a previous history of distress, low income, female sex, and beta blocker use.

Cohort study of Silastic obstetric vacuum cup deliveries: II. Unsuccessful vacuum extraction

In a cohort analysis of Silastic vacuum extractor deliveries, 65% were completed with the vacuum extractor alone, 24% with outlet forceps, 3% with midforceps, and 7% with cesarean section (vacuum extractor-cesarean). Control groups were formed by using the next sequential forceps delivery, spontaneous vaginal delivery, and every second cesarean section after a trial of labor. The infants were examined using a neurobehavioral scale, an encephalopathy assessment, cranial ultrasound, and indirect ophthalmoscopy. In the combined vacuum extractor and forceps delivery subgroup (vacuum extractor-forceps), all but 3% were converted from a high mid-forceps delivery to outlet forceps by the initial vacuum extractor procedure, thus eliminating many difficult midforceps deliveries. The study yielded no significant difference in maternal morbidity between vacuum extractor-forceps and forceps delivery, no difference in vaginal trauma for vacuum extractor-cesarean versus vacuum extractor delivery, and no greater hospital stay, infection rate, or need for transfusion for either vacuum extractor-forceps versus forceps delivery or vacuum extractor-cesarean versus cesarean delivery. Neonatal morbidity did not differ between successful and unsuccessful trial of vacuum extractor, except for an increased frequency of retinal hemorrhage. The frequency of scalp trauma, including cephalohematoma, did not differ between vacuum extractor-forceps and forceps delivery, or between vacuum extractor-cesarean and vacuum extractor delivery. For vacuum extractor-forceps versus forceps delivery and vacuum extractor-cesarean versus cesarean section, there were no significant differences in neurobehavioral or encephalopathy scores, or in the frequency of neonatal jaundice, facial palsy, anemia, fractures, or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Nucleotide specificity for reactivation of organelle movements in permeabilized axons

In a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 microM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP-PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein-like ATPase, rather than a myosin, is involved in fast axonal transport.

Selective inhibition of retrograde axonal transport by erythro-9-[3-(2-hydroxynonyl)]adenine

Retrograde transport of microscopically visible organelles in isolated lobster axons was selectively inhibited by erythro-9-[3-(2-hydroxynonyl)]adenine (EHNA), with little or no effect on anterograde transport. The retrograde velocity was reduced both in living axons and in permeabilized axons in which movement was reactivated with exogenous ATP. This is the first report of an agent that selectively inhibits axonal transport in one direction.

Fast axonal transport in permeabilized lobster giant axons is inhibited by vanadate

We have developed a method for permeabilizing axons and reactivating the fast transport of microscopically visible organelles. Saltatory movements of organelles in motor axons isolated from lobster walking legs were observed using Nomarski optics and time-lapse video microscopy. In the center of the axon most of the particles and mitochondria moved in the retrograde direction, but immediately below the axolemma the majority moved in the anterograde direction. When axons were permeabilized with 0.02% saponin in an adenosine 5'-triphosphate (ATP)-free "internal" medium, all organelle movement ceased. Saltatory movements resembling those in intact axons immediately reappeared upon the addition of MgATP. Very slight movement could be detected with ATP concentrations as low as 10 microM, and movement appeared to be maximal with 1 to 5 mM ATP. Vanadate, which does not affect axonal transport in intact axons, inhibited the reactivated organelle movements in permeabilized axons. Movement was rapidly and reversibly inhibited by 50 to 100 microM sodium orthovanadate. The effects of vanadate, including the time course of inhibition, its reversibility, and its concentration dependence, are consistent with the hypothesis that a dyneinlike like molecule may play a role in the mechanism of fast axonal transport.

Comparison of liquid and agar-solidified defined media regarding the physiological mechanism by which beta-2-thienylalanine inhibits growth of Escherichia, Shigella, and Salmonella cultures

Growth comparisons were made, using Shigella, Escherichia, and Salmonella cultures, in liquid and agar-solidified defined media containing beta-2-thienylalanine (beta-2-t). The comparisons were performed to determine the nature of growth inhibition by beta-2-t under different physical growth conditions. In a plate assay, with increasing beta-2-t mixed into the agar, inhibition of Escherichia and Shigella increased. However, Salmonella cultures were not inhibited even at the highest beta-2-t concentrations used. With beta-2-t added to liquid cultures, however, dose-response growth relationships were exhibited by all three genera. The differences occurring in beta-2-t inhibition between liquid and plate assay conditions were not due to composition of culture plates, time of challenge of cultures with beta-2-t, availability of oxygen and associated differences in ratios of volume of media to available surface area, selection of mutants in the plate assay, or to extractable substances from the agar. However, when beta-2-t diffusion into the liquid medium was delayed by using agar plug diffusion cultures, a physiological mechanism was demonstrable which largely protected Salmonella cultures, but not Escherichia and Shigella cultures, from growth inhibition.

The assay on a defined medium of the effects of beta-2-thienylalanine on the growth of anaerobic bacterial isolates from phenylketonuric patients

Faecal samples were taken from three diet-managed phenylketonuric children to determine effects of beta-2-thienylalanine (beta-2-t) on indigenous bacteria. From sample swabs, 127 anaerobes were identified and tested for beta-2-t inhibition on a phenylalanine (Phe)-free medium, Anaerobe Inhibition Test (AIT) agar. Of the isolates, 77.9% grew sufficiently to assay reactions on at least 25% of AIT plates. Using Phe-containing Columbia agar, 86.5% of the strains could be assayed. None of 28 Bacteroides cultures was inhibited by beta-2-t on AIT. Of the genera, Bifidobacterium, Eubacterium, Lactobacillus, Peptostreptococcus, and Propionibacterium, no isolates which would grow on AIT were inhibited. At least one isolate of each of the genera Peptococcus, Fusobacterium, and Clostridium was inhibited. Of 127 total isolates, only nine were inhibited by beta-2-t on AIT, and inhibition was abolished on Columbia agar. Thirty-nine "aerobes" were isolated from the same patients. Strains of the genera tested reacted similarly to previously tested strains from non-PKU sources. Also, anaerobically isolated Excherichia coli were inhibited, while Streptococcus faecalis cultures were not, confirming results on aerobically-isolated non-PKU cultures of the same species. These studies, the first dealing with beta-2-t and anaerobic bacteria, suggest that little change in intestinal bacterial populations might be expected during in vivo beta-2-t treatment.

Effects of increasing Mg++ ion concentration on the PKU monitoring assay

Inaccuracies in a commonly used bacterial inhibition assay for blood phenylalanine levels arise when the Mg++ ion concentration in the assay medium is increased. This has practical implications in the diagnosis and management of phenylketonuria.

Colonization by Salmonella typhimurium and Shigella flexneri III of the gastrointestinal tract of mice treated with beta-2-thienylalanine and streptomycin

Mice fed beta-2-thienylalanine (beta-2-T) by oesophageal tube were no more susceptible to gastrointestinal tract colonization by Salmonella typhimurium or Shigella flexneri III than control mice fed water. In both beta-2-T-fed and water-fed groups, the increasing dosage of S. typhimurium, in logarithmic increments to groups of mice, resulted in increasing numbers of these bacteria detectable on dilution plates from organ homogenates. Colonization by S. flexneri III only occurred at a dosage of 10(8) bacteria for both groups. Pretreatment with 50 mg streptomycin allowed 10(3) Salmonella or 10(4) Shigella to colonize both beta-2-T and water-fed groups. Coliforms, inhibited by beta-2-T under certain conditions in vitro, were found in equal numbers in both groups. No obvious differences were noted in either types of other bacteria detected or numbers recovered from the two groups. No gross behavioural changes were noted in mice fed beta-2-T and not challenged with pathogenic bacteria, and no pathological changes were noted in hepatic or splenic tissues. With increasing Salmonella dosage, collections of polymorphonuclear leucocytes, which were almost focal, and increased numbers of giant cells were noted in splenic red pulp areas, in both groups.

Effects of changes in Mg++ ion concentration upon bacterial inhibition by beta-2-thienylalanine in defined media

Variation in the inhibition of growth of Escherichia coli and Shigella sp. in various media containing beta-2-thienylalanine was attributed to differences in concentrations of Mg++ ions. Random blood samples 112 infants were tested for elevated phenylalanine in the phenylketonuria (PKU) screening assay. Magnesium ion levels also affected the results of this assay. At 0.05 g/1 MgSO4, the concentration present in commerical PKU test agar, four false positives were detected, while no readings could be made due to overgrowth of the Bacillus subtilis test strain when the concentration was increased to 0.1 g/1.

Isolation of bacteriophage-like particles from uninduced Clostridium tetani cultures

The isolation of hexagonal-headed, tailless, bacteriophage-like particles from uninduced cultures of Clostridium tetani is described. Clear, round, 1--3 mm diameter plaques were noted on Clostrisel agar plates, which were overlaid with soft agar inoculated with 7--14 day broth cultures. Particles were detected by transmission electron microscopy from broth cultures seeded with scrapings from the plaques. Both electron dense and electron lucent heads were noted. An electron dense head was observed attached to the surface of a dividing bacterium.

Differentiation of pathogenic, gram-negative, bacterial genera in the presence of beta-2-thienylalanine

Described in a fast screening assay for aid in the differentiation of bacterial genera. Salmonella is separated from Escherichia and Shigella, as a generic group on the basis of an inhibition assay incorporating beta-2-thienylalanine, and using a defined medium. The assay is also usable for confirmation of taxonomic differences between genera. The inhibition reaction, readable as an 'all-or-none' phenomenon, follows a dose-response relationship for cultures affected by beta-2-thienylalanine, and is unaffected by the growth phase of the culture.