The beta-D-xylosidase of Trichoderma reesei is a multifunctional beta-D-xylan xylohydrolase

An extracellular multifunctional beta-D-xylan xylohydrolase, previously described as beta-xylosidase, was purified from Trichoderma reesei RUT C-30 to physical homogeneity. The active enzyme was a 100 (+/-5) kDa glycosylated monomer that exhibited a pl of 4.7. Its activity was optimal at pH 4 and it was stable between pH 3 and 6. Its temperature-stability was moderate (70 degrees zero of activity remaining after 60 min at 50 degrees C) and optimal activity was observed at 60 degrees C. It is capable of hydrolysing beta-1.4-xylo-oligosaccharides [degree of polymerization (DP) 2-7], the apparent Vmax increasing with increasing chain length. The enzyme also attacked debranched beech-wood (Lenzing) xylan and 4-O-methylglucuronoxylan, forming xylose as the only end product. The K(m) for xylan was 0.7 g/l. For this reason we consider the enzyme to be a beta-D-xylan xylohydrolase. The enzyme also exhibits alpha-L-arabinofuranosidase activity on 4-nitrophenyl alpha-L-arabinofuranoside, and evidence is presented that this is not caused by an impurity in the enzyme preparation. The beta-D-xylan xylohydrolase exhibits glycosyltransferase activity with xylo-oligosaccharides and at high concentrations of 4-nitrophenyl beta-D-xylopyranoside (4-Nph-beta-Xyl). The enzyme hydrolyses beta-1, 4-linkages preferentially to beta-1,3-linkages, and beta-1,2-linked xylo-oligosaccharides are not hydrolysed at all. The enzyme liberates terminal beta-1,4-xylopyranose residues linked to a 2-O-substituted xylopyranose residue, but not that linked to a 3-O-substituted xylopyranose residue. The enzyme does not attack methyl, methyl 1-thio-benzyl or butyl l-thio-beta-D-xylopyranosides and 4-naphthyl, 2-naphthyl and phenyl beta-D-xylopyranosides.

A multinational investigation of the impact of subcutaneous sumatriptan. I: Design, methods and clinical findings

This report describes the design, methods and clinical results of a prospective sequential multinational (5 countries) study conducted to evaluate the effects of subcutaneous sumatriptan on health-related quality of life, workplace productivity, clinical parameters and patient satisfaction. Adult patients with moderate to severe migraine initially received customary therapy for migraine episodes for 12 weeks, followed by 24 weeks' treatment with self-administered subcutaneous sumatriptan 6 mg. Demographic, baseline, health-related quality of life and patient satisfaction rating data were collected during visits to the clinic. Data relating to migraine symptoms, migraine therapy, work productivity and non-work activity time were collected on diary cards filled out by the patients. 749 patients were recruited to the study and 637 received at least 1 dose of sumatriptan. Overall, 75.5% of migraines were successfully treated within 2 hours with sumatriptan compared with 31.9% with customary therapy; 36% of patients reported complete relief at 2 hours with sumatriptan treatment compared with 1% of patients receiving customary therapy. 69% of patients successfully treated 70% of their migraines with sumatriptan within 2 hours, compared with 12% of patients with customary therapy. No serious adverse events were reported; 50% of patients reported an adverse event during the 12-week customary therapy phase and 89% of patients during the 24-week sumatriptan phase. These clinical results, which are consistent with those reported in randomised blinded studies of subcutaneous sumatriptan, suggest that relief of migraine symptoms occurs more often, and in less time, in patients receiving subcutaneous sumatriptan rather than customary therapy as their primary medication.

A multinational investigation of the impact of subcutaneous sumatriptan. III: Workplace productivity and non-workplace activity

This report presents the workplace productivity and non-workplace activity results of a multinational study of the effects of subcutaneous sumatriptan 6 mg in the acute treatment of migraine compared with patient's customary therapy. Patients diagnosed with migraine treated their symptoms for 24 weeks with subcutaneous sumatriptan after a 12-week period of treating symptoms with their customary (non-sumatriptan) therapy. Patients used diary cards to record information concerning the effects of migraine on workplace productivity and non-workplace activity time. The average workplace productivity time lost was 23.4 hours per patient during 12 weeks of customary therapy, compared with 7.2 and 5.8 hours per patient during the first and second 12-week periods of sumatriptan therapy, respectively. An average of 9.3 hours of non-workplace activity time was lost per patient during the customary therapy phase, compared with 3.2 and 2.8 hours during the first and second 12-week periods of sumatriptan therapy, respectively. Treatment of migraine with subcutaneous sumatriptan compared with customary therapy was associated with an average gain per patient of approximately 16 hours of workplace productivity time and 6 hours of non-workplace activity time, over a 3-month period.

A multinational investigation of the impact of subcutaneous sumatriptan. II: Health-related quality of life

The aim of this prospective sequential multinational (5 countries) study was to concurrently evaluate the effects of subcutaneous sumatriptan on clinical parameters, health-related quality-of-life (HRQOL) measures, workplace productivity and patient satisfaction. This report presents the HRQOL results. 582 patients (aged 18 to 65 years) with moderate to severe migraine received their customary antimigraine therapy for 12 weeks and then subcutaneous sumatriptan for 24 weeks. The Short Form-36 Health Survey and the Migraine-Specific Quality of Life Questionnaire were completed at a screening visit (base-line), at the end of the 12-week customary therapy phase, and at 12 and 24 weeks of the sumatriptan phase. Scores for most of the Short Form-36 dimensions improved significantly (p < 0.05) after 12 and 24 weeks of sumatriptan therapy compared with 12 weeks of customary therapy, in each country. Similarly, scores on all Migraine-Specific Quality of Life Questionnaire dimensions were significantly (p < 0.05; paired t-test) improved after 12 weeks (in all countries) and 24 weeks (in 4 of 5 countries) of sumatriptan therapy compared with 12 weeks of customary therapy. This study demonstrates that, in 5 countries, treatment of migraine attacks with subcutaneous sumatriptan compared with customary therapy was associated with improvements in HRQOL, as measured by both general health status and disease-specific instruments.

Sensitivity-enhanced echo-planar MRI at 1.5T using a 5 x 5 mesh dome resonator

In this work a 5 x 5 mesh dome resonator that has been optimized for functional brain imaging is presented. The resonator was reduced in length and diameter compared with previous versions to reduce sample losses, thus enhancing the signal-to-noise ratio of the acquired data. In addition, a 5 x 5 mesh design was employed, which offered improved axial homogeneity over an earlier 3 x 3 mesh version. The new resonator exhibited high sensitivity and good homogeneity over the brain volume, permitting analysis of functional activation over large areas of the cerebral cortex. In a direct comparison with a standard clinical head-imaging resonator, the high sensitivity of the 5 x 5 mesh dome resonator resulted in greater statistical confidence in functional activation.

Effects of gender, body composition, and menopause on plasma concentrations of leptin

Circulating concentrations of leptin ([leptin]) vary directly with body mass index and percentage body fat, and may thus constitute an afferent limb of a system regulating body fatness. We tested the hypotheses that: 1) Plasma [leptin] vary more directly with absolute fat mass than with fractional body fatness per se: and 2). The relationship between fat mass and [leptin] is significantly affected by gender and by menopausal status. [Leptin] in the post-absorptive state was examined in 67 subjects (26 male, 20 premenopausal female, 21 postmenopausal females; 43 never-obese, 24 obese) at usual body weight. Body composition was determined by hydrodensitometry, and [leptin] was determined by a double antibody ELISA assay. In male and pre-menopausal female subjects, subcutaneous adipose tissue aspirations were performed for determination of adipocyte volume by the osmium fixation method, and a 3 hour oral glucose tolerance tests was performed. At usual body weight, ([leptin]) was better correlated with absolute fat mass than with body mass index (BMI) or percentage body fat. BMI and % body fat did not account for any of the variance in [leptin] beyond that attributable to FM, per se. The regression equations relating FM to [leptin] did not differ significantly between obese and never-obese subjects. [Leptin] and fasting serum insulin concentrations were significantly correlated in males only. [Leptin] was significantly higher in pre- and post-menopausal females compared to males, even when [leptin] was corrected for differences in body composition (pre-menopausal females > post-menopausal females > males). While plasma [leptin], corrected for FM, declines significantly in women post-menopause, this decline is not sufficient to account for the striking sexual dimorphism in the relationship of leptin to fat mass. This sexual dimorphism is apparently also due, in part, to a suppressive effect of circulating androgens on [leptin].

A gene correlate of geotaxis near Adh (2-50.1) in Drosophila melanogaster

As part of a long-term study (38+ years) to identify genetic correlates of geotaxis in Drosophila melanogaster, the investigators report the results of allozyme-level analyses of 2 lines derived from hybridizing high- and low-selected lines that have evolved stable, extreme expressions of geotaxis. Allelic variation at Adh was associated with geotactic performance in 1 hybrid-derived line, but not in another, after 66 free-mating generations beyond the F2 generation. A second-chromosome gene correlate of geotaxis may lie within 1 map unit of Adh. Population genetic analyses suggest that there were different selection pressures on the hybrid-derived lines and that the fixation of PGD-A in the high-geotaxis line was probably due to a founder-effect event.

Redox sites of NMDA receptors can modulate epileptiform activity in hippocampal slices from kainic acid-treated rats

Using an animal model of temporal lobe epilepsy, the kainic acid lesioned rat hippocampus, we have evaluated the possibility of modulating glutamate N-methyl-D-aspartate (NMDA) receptor-dependent evoked epileptiform activity through the manipulation of NMDA receptor redox sites. Epileptiform activity was recorded extracellularly from hippocampal slices, in the stratum pyramidale of the CA1 area, and the effects of the oxidizing reagent 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and the reducing agent Tris(2-carboxy ethyl)phosphine (TCEP) on these responses were quantified. Epileptiform activity was substantially reduced in the presence of DTNB but was fully reinstated with the application of TCEP. The effects of both drugs persisted even after wash. Epileptiform activity was totally abolished in the presence of the NMDA receptor antagonist D-2-amino-5-phosphonovaleric acid. These results suggest that epileptiform activity can be controlled by manipulation of the redox sites of NMDA receptors and raise the possibility of developing new anticonvulsant drugs which do not fully block NMDA receptor-mediated synaptic transmission.

Human fatty acid synthesis is stimulated by a eucaloric low fat, high carbohydrate diet

A new experimental approach was used to determine whether a eucaloric, low fat, high carbohydrate diet increases fatty acid synthesis. Normally volunteers consumed low fat liquid formula diets (10% of calories as fat and 75% as glucose polymers, n = 7) or high fat diets (40% of calories as fat and 45% as glucose polymers, n = 3) for 25 d. The fatty acid composition of each diet was matched to the composition of each subject's adipose tissue and compared with the composition of VLDL triglyceride. By day 10, VLDL triglyceride was markedly enriched in palmitate and deficient in linoleate in all subjects on the low fat diet. Newly synthesized fatty acids accounted for 44 +/- 10% of the VLDL triglyceride. Mass isotopomer distribution analysis of palmitate labeled with intravenously infused 13C-acetate confirmed that increased palmitate synthesis was the likely cause for the accumulation of triglyceride palmitate and "dilution" of linoleate. In contrast, there was minimal fatty acid synthesis on the high diet. Thus, the dietary substitution of carbohydrate for fat stimulated fatty acid synthesis and the plasma accumulation of palmitate-enriched, linoleate-deficient triglyceride. Such changes could have adverse effects on the cardiovascular system.

Cytogenetic findings in 175 patients indicate that items of the Kiel classification should not be disregarded in the REAL classification of lymphoid neoplasms

Cytogenetics have proved to be a valuable tool for classifying systemic lymphatic neoplasms, as this technique allows different stem line aberrations and clonal developments to be distinguished. This study was designed to analyze how far groups defined according to common cytogenetic features correlated with their position in either the Kiel (KC) or the REAL classification. Cytogenetic analyses were performed on material from 175 patients with lymphoid neoplasms (LN). Samples were prepared from peripheral blood and bone marrow in acute lymphoblastic leukemia (ALL), from bone marrow in multiple myeloma (MM), and from lymph node biopsies in lymphomas. The results of this study support the inclusion of ALL, MM, and extranodal lymphomas into a comprehensive classification, because their chromosomal aberrations were always characteristic for LN. From the cytogenetic point of view, a subgroup of ALL appears as a leukemic manifestation of lymphoblastic lymphoma. MM have structural aberrations of chromosomes 1, 11, and 14 and secondary aberrations of chromosomes 3, 6, 7, 12, 13, and 18, all of which are characteristic for lymphatic disease. The groups with follicle center cell lymphoma and mantle cell lymphoma correlate well with our results both in the low-grade subtype and in the blastic variant type, the majority of cases demonstrating t(14; 18) and its variants and t(11; 14), respectively. In contrast, the group of diffuse large B-cell (DLB) lymphomas proved to be heterogeneous on the basis of our cytogenetic results. Accordingly, we would suggest keeping the immunoblastic lymphoma (IB) subtype defined by the KC. IB demonstrates no stem line aberration in common with any other group and seems to be characterized by stem line aberrations involving chromosomes 3 and 6. As some DLB lymphomas have a t(14;18) or variant translocations involving chromosome 18, they should either be separated as a subgroup or included into the group of follicle center lymphomas.

A comparative study of different means of assessing long-term energy expenditure in humans

We compared three independent techniques for measurement of total energy expenditure (TEE) in human subjects: 1) weight-maintaining energy intake (dietTEE), 2) 24-h chamber calorimetry (chamberTEE), and 3) differential elimination rates 2H2O and H(2)18O (isotopeTEE). Twenty-three healthy adult in-patients [19 never obese (NO), 2 obese (OB), and 2 formerly-obese (RO); 9 female, 14 malel] ingested a liquid formula diet (40% of calories as fat, 45% carbohydrate, 15% protein), the volume of which was adjusted until body weight was stable for at least 14 days. Body composition was then determined by hydrodensitometry, isotope dilution, and dual photon beam absorptiometry (DXA). The thermic effect of feeding (TEF) and resting energy expenditure [REE; measured before arising (dietREE) and after arising (chamberREE)] were determined by indirect calorimetry. Non-resting energy expenditure (NREE) was calculated as NREE = TEE - (REE + TEF). Subjects then gained or lost 10% of their body weight and were restudied as described above. All measures of TEE were significantly correlated (dietTEE vs. chamberTEE r2 = 0.75; dietTEE vs. isotopeTEE r2 = 0.88; isotopeTEE vs. chamberTEE r2 = 0.73; P < 0.0001). ChamberTEE (mean +/- SE = 2,107 +/- 64 kcal/day) was approximately 20% lower than either dietTEE (2,536 +/- 94 kcal/day, P < 0.0001) or isotopeTEE (2,564 +/- 83 kcal/day, P < 0.0001). When data were normalized to metabolic mass, weight gain of 10% was associated with significant increases in dietTEE (P < 0.005) and isotopeTEE (P < 0.05) but not chamberTEE; weight loss of 10% was associated with significant reductions in dietTEE (P < 0.005) and isotopeTEE (P < 0.05) but not chamberTEE. We conclude that measures of energy expenditure obtained in a highly controlled environment by caloric titration (dietTEE) or differential excretion rates of 2H2O and H(2)18O (isotopeTEE) are not significantly different and that measurements of TEE obtained in a respiratory chamber (chamberTEE) are significantly lower than dietTEE or isotopeTEE, probably largely due to limitations on physical activity in the chamber.

Activated partial thromboplastin time and outcome after thrombolytic therapy for acute myocardial infarction: results from the GUSTO-I trial

BACKGROUND

Although intravenous heparin is commonly used after thrombolytic therapy, few reports have addressed the relationship between the degree of anticoagulation and clinical outcomes. We examined the activated partial thromboplastin time (aPTT) in 29,656 patients in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) trial and analyzed the relationship between the aPTT and both baseline patient characteristics and clinical outcomes.

METHODS AND RESULTS

Intravenous heparin was administered as a 5000-U bolus followed by an initial infusion of 1000 U/h, with dose adjustment to achieve a target aPTT of 60 to 85 seconds. aPTTs were collected 6, 12, and 24 hours after thrombolytic administration. Higher aPTT at 24 hours was strongly related to lower patient weight (P < .00001) as well as older age, female sex, and lack of cigarette smoking (all PT< .0001). At 12 hours, the aPTT associated with the lowest 30-day mortality, stroke, and bleeding rates was 50 to 70 seconds. There was an unexpected direct relationship between the aPTT and the risk of subsequent reinfarction. There was a clustering of reinfarction in the first 10 hours after discontinuation of intravenous heparin.

CONCLUSIONS

Although the relationship between aPTT and clinical outcome was confounded to some degree by the influence of baseline prognostic characteristics, aPTTs higher than 70 seconds were found to be associated with higher likelihood of mortality, stroke, bleeding, and reinfarction. These findings suggest that until proven otherwise, we should consider the aPTT range of 50 to 70 seconds as optimal with intravenous heparin after thrombolytic therapy.

Human eating: evidence for a physiological basis using a modified paradigm

The aim of these studies was to determine if meal requests and changes in hunger ratings in humans were related to spontaneous changes in blood glucose concentration. In our first study, 18 healthy subjects were acutely isolated from food ant time cues. Blood glucose was continuously monitored online and visual analog ratings of hunger were obtained following an overnight fast. Spoken meal requests, if they occurred, were also recorded. In 83% of the subjects, both the perception and behavioral expression of hunger, as assessed by changes in hunger ratings and meal requests, were preceded by, and correlated with, brief, transient declines in blood glucose (nadir: -10% at 27 min). The pattern, magnitude and time course of these declines was similar to those observed in rats. This significant association, between increased expression of hunger and declines in blood glucose, is being tested in a second, ongoing study using acute insulin infusions to mimic spontaneous transient declines in blood glucose. Each subject was studied twice: either insulin or saline was infused while hunger ratings were obtained. Preliminary results in five subjects indicate that hunger ratings increased after insulin-induced transient declines in blood glucose. No change in hunger ratings occurred when blood glucose concentration was stable. These results suggest that this temporal pattern of blood glucose reflects an antecedent physiological event or provides a signal related to the expression of hunger in humans. Further understanding of human eating may result from investigation of the complex interaction of physiological and other factors in an experimental setting that allows the expression the behavior under study.

Liquid secondary ion mass spectrometry of methyl glycosides of oligosaccharides using matrices containing carboxamides

Intense cluster ions corresponding to proton-bound hetero-dimers of an amide molecule and an oligosaccharide molecule are observed in the liquid secondary ion mass spectra of methyl glycosides of oligoxylans if a solution of an aliphatic carboxamide in glycerol is used as the liquid matrix. These cluster ions are particularly abundant and persist for a long period if urea (U) or thiourea (TU) is used as the matrix additive. In these cases, cluster ions containing more than one molecule of U or TU and two oligosaccharide molecules are also observed. The intense signal due to the proton-bound hetero-dimer between U or TU and the oligosaccharide can be used with advantage for a molecular weight determination. The bonding interactions between a protonated saccharide molecule and a molecule U or TU in the proton-bound hetero-dimers are so strong that the urea molecules remain attached to the fragment ions during the decay of metastable cluster ions and even during collision-induced dissociation. Thus, the mass-analysed ion kinetic energy spectra of these proton-bound hetero-dimers are dominated by abundant cluster ions [Bn+U] and [Ym+U] arising from cleavage of the glycosidic bonds within the oligosaccharides. The collisionally-activated mass spectra of the proton-bound hetero-dimers additionally contain peaks of the free ions Bn and Ym. Therefore, these spectra clearly reflect the arrangement of the monosaccharide residues in the oligosaccharide and can be used conveniently for structural analysis.

Weighing the options: criteria for evaluating weight-management programs. The Committee to Develop Criteria for Evaluating the Outcomes of Approaches to Prevent and Treat Obesity

The United States is experiencing an epidemic of obesity among both adults and children. Approximately 35 percent of women and 31 percent of men age 20 and older are considered obese, as are about one-quarter of children and adolescents. While government health goals for the year 2000 call for no more than 20 percent of adults and 15 percent of adolescents to be obese, the prevalence of this often disabling disease is increasing rather than decreasing. Obesity, of course, is not increasing because people are consciously trying to gain weight. In fact, tens of millions of people in this country are dieting at any one time; they and many others are struggling to manage their weight to improve their appearance, feel better, and be healthier. Many programs and services exist to help individuals achieve weight control. But the limited studies paint a grim picture: those who complete weight-loss programs lose approximately 10 percent of their body weight, only to regain two-thirds of it back within 1 year and almost all of it back within 5 years. These figures point to the fact that obesity is one of the most pervasive public health problems in this country, a complex, multifactorial disease of appetite regulation and energy metabolism involving genetics, physiology, biochemistry, and the neurosciences, as well as environmental, psychosocial, and cultural factors. Unfortunately, the lay public and health-care providers, as well as insurance companies, often view it simply as a problem of willful misconduct--eating too much and exercising too little. Obesity is a remarkable disease in terms of the effort required by an individual for its management and the extent of discrimination its victims suffer. While people often wish to lose weight for the sake of their appearance, public health concerns about obesity relate to this disease's link to numerous chronic diseases that can lead to premature illness and death. The scientific evidence summarized in Chapter 2 suggests strongly that obese individuals who lose even relatively small amounts of weight are likely to decrease their blood pressure (and thereby the risk of hypertension), reduce abnormally high levels of blood glucose (associated with diabetes), bring blood concentrations of cholesterol and triglycerides (associated with cardiovascular disease) down to more desirable levels, reduce sleep apnea, decrease their risk of osteoarthritis of the weight-bearing joints and depression, and increase self-esteem. In many cases, the obese person who loses weight finds that an accompanying comorbidity is improved, its progression is slowed, or the symptoms disappear. Healthy weights are generally associated with a body mass index (BMI; a measure of whether weight is appropriate for height, measured in kg/m2) of 19-25 in those 19-34 years of age and 21-27 in those 35 years of age and older. Beyond these ranges, health risks increase as BMI increases. Health risks also increase with excess abdominal/visceral fat (as estimated by a waist-hip ratio [WHR] > 1.0 for males and > 0.8 for females), high blood pressure (> 140/90), dyslipidemias (total cholesterol and triglyceride concentrations of > 200 and > 225 mg/dl, respectively), non-insulin-dependent diabetes mellitus, and a family history of premature death due to cardiovascular disease (e.g., parent, grandparent, sibling, uncle, or aunt dying before age 50). Weight loss usually improves the management of obesity-related comorbidities or decreases the risks of their development. The high prevalence of obesity in the United States together with its link to numerous chronic diseases leads to the conclusion that this disease is responsible for a substantial proportion of total health-care costs. We estimate that today's health-care costs of obesity exceed $70 billion per year.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of diadenosine polyphosphates, ATP and angiotensin II on membrane voltage and membrane conductances of rat mesangial cells

Diadenosine polyphosphates have been shown to influence renal perfusion pressure. As mesangial cells may contribute to these effects we investigated the effects of diadenosine triphosphate (Ap3A), diadenosine tetraphosphate (Ap4A), diadenosine pentaphosphate (Ap5A) and diadenosine hexaphosphate (Ap6A) on membrane voltage (Vm) and membrane conductance (gm) in mesangial cells (MC) of normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats in primary and long-term culture. We applied the patch-clamp technique in the fast-whole-cell configuration to measure Vm and gm. To compare the effects of diadenosine polyphosphates with hitherto known agonists we also tested adenosine 5&acute;-triphosphate (ATP) and angiotensin II (Ang II). As there was no significant difference in the Vm values in MC of WKY (-42 +/- 1 mV, n = 70) and SHR rats (-45 +/- 2 mV, n = 99) as well as in the agonist-induced changes of Vm, all data were pooled. The Vm of all the cells was -44 +/- 1 mV (n = 169) and gm was 15.9 +/- 1.8 nS (n = 141). Ion-exchange experiments showed the presence of a K+ and a non-selective cation conductance in resting MC whereas a Cl- conductance or a Na+-selective conductance could not be observed. Ap3A, Ap4A, Ap5A, AP6A and ATP each at a concentration of 5 micromol/l, led to a significant depolarization of Vm by 5 +/- 2 mV (n = 14), 7 +/- 1 mV (n = 25), 3 +/- 1 mV (n = 23), 2 +/- 1 mV (n = 16), and 14 +/- 2 mV (n = 23), respectively. For Ap4A, the most potent diadenosine polyphosphate, we determined the half-maximally effective concentration (EC50) as 6 micromol/l (n = 5-25), for ATP as 2 micromol/l (n = 9-37), and for Ang II as 8 nmol/l (n = 6-18). Ap4A 100 micromol/l increased gm significantly by 55 +/- 20% (n = 16), 100 micromol/l ATP by 135 +/- 60% (n = 18). The diadenosine polyphosphates examined were able to depolarize Vm (Ang II > ATP > Ap4A > Ap3A > Ap5A > Ap6A) by activation of a Cl- conductance and a non-selective cation conductance, as do ATP or Ang II.

Non-involvement of the redox site of NMDA receptors in bidirectional synaptic plasticity in the CA1 area of the rat hippocampus in vitro

We have examined the effects of the redox reagent 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) on synaptic potentials recorded extracellularly from the CA1 area in hippocampal slices following low frequency stimulation (LFS) and tetanic stimulation (TS). Application of DTNB (200 microM) neither changed synaptic responses, nor prevented the expression of TS-induced long-term potentiation of synaptic responses and their depotentiation by LFS. Conversely, in naive slices, LFS still induced long-term depression of synaptic responses following application of DTNB. This depression could be subsequently reversed with a TS. It is concluded that the redox state of N-methyl-D-aspartate receptors does not affect the expression of long-term potentiation and depression of synaptic responses.

Illusory contours activate specific regions in human visual cortex: evidence from functional magnetic resonance imaging

The neural basis for perceptual grouping operations in the human visual system, including the processes which generate illusory contours, is fundamental to understanding human vision. We have employed functional magnetic resonance imaging to investigate these processes noninvasively. Images were acquired on a GE Signa 1.5T scanner equipped for echo planar imaging with an in-plane resolution of 1.5 x 1.5 mm and slice thicknesses of 3.0 or 5.0 mm. Visual stimuli included nonaligned inducers (pacmen) that created no perceptual contours, similar inducers at the corners of a Kanizsa square that created illusory contours, and a real square formed by continuous contours. Multiple contiguous axial slices were acquired during baseline, visual stimulation, and poststimulation periods. Activated regions were identified by a multistage statistical analysis of the activation for each volume element sampled and were compared across conditions. Specific brain regions were activated in extrastriate cortex when the illusory contours were perceived but not during conditions when the illusory contours were absent. These unique regions were found primarily in the right hemisphere for all four subjects and demonstrate that specific brain regions are activated during the kind of perceptual grouping operations involved in illusory contour perception.

Autonomic nervous system activity in weight gain and weight loss

Studies in both animals and humans indicate that the autonomic nervous system (ANS) responds to changes in systemic energy balance. In the present study, ANS response to weight change was examined by sequential blockade of cardiac autonomic innervation with parasympathetic (atropine) and sympathetic (esmolol) blockers. Change in heart period (interbeat interval) from baseline after atropine defined the amount of parasympathetic control (PC), and the subsequent change after esmolol defined the amount of sympathetic control (SC). In nonobese subjects, weight gain to 10% above initial body weight resulted in a decrease in PC and an increase in SC, and conversely, weight loss to 10% below initial weight resulted in an increase in PC and a decrease in SC. In obese subjects, weight loss resulted in the same pattern of changes in PC and SC. The major changes were in the parasympathetic arm of the ANS. These findings support the hypothesis that the ANS acts to oppose weight change.