In vitro neurite extension by granule neurons is dependent upon astroglial-derived fibroblast growth factor

When grown in the absence of astroglial cells, purified mouse cerebellar granule neurons survive less than 36 hr and do not extend neurites. Here we report that low concentrations of basic fibroblast growth factor (bFGF, 1-25 ng/ml) maintained the viability and promoted the differentiation of purified granule neurons. The effect of bFGF on granule cell neurite outgrowth was dose dependent. Neurite outgrowth was stimulated markedly in the presence of 1-25 ng/ml bFGF, but effects were not seen below 1 ng/ml or above 50 ng/ml. When affinity-purified antibodies against bFGF (1-5 micrograms/ml) were added either to purified granule cells or to co-cultures of neurons and astroglial cells, process extension by granule neurons was severely impaired. The inhibition of neurite outgrowth in the presence of anti-bFGF antibodies was reversed by the addition of 25 ng/ml of exogenous bFGF. In addition to neuronotrophic effects, bFGF influenced the rate of growth of the astroglial cells. This result depended on whether the astroglia were grown in isolation from neurons, where low doses of bFGF (10-25 ng) stimulated glial growth, or in coculture with neurons, where much higher doses of bFGF (100-250 ng/ml) were needed for glial mitogenesis. Immunoprecipitation of lysates from 35S-labeled cerebellar astroglial cells with anti-bFGF antibodies revealed a single band after SDS-PAGE at 18,000 Da, the molecular weight of bFGF. These results indicate that glial cells synthesize bFGF and are possibly an endogenous source of bFGF in cerebellar cultures. Thus, astroglial cells synthesize soluble factors needed for neuronal differentiation.

Immunological detection of minimal residual disease in children with acute lymphoblastic leukaemia

BACKGROUND

The clinical significance of submicroscopic levels of leukaemic cells in bone-marrow aspirates from children with acute lymphoblastic leukaemia (ALL) remains controversial. We prospectively determined the frequency and prognostic importance of minimal residual disease detected by a rapid immunological assay in bone-marrow aspirates of children with ALL.

METHODS

158 children with newly diagnosed ALL received 6 weeks of remission-induction chemotherapy. Once complete clinical remission was attained the patients received 2 weeks of consolidation therapy followed by continuation therapy. Bone-marrow aspirates were collected after induction therapy and during weeks 14, 32, and 56 of continuation therapy, and then at 120 weeks (end of therapy). Cells with leukaemia-associated immunophenotypes were investigated by multiparameter flowcytometry capable of detecting one leukaemic cell among 10,000 normal cells.

FINDINGS

The proportion of patients with detectable leukaemic cells was 23% at remission induction and 17% at week 14 of continuation therapy, decreasing to 5% and 4% at weeks 32 and 56. None of the 65 samples examined at completion of therapy (week 120) showed evidence of disease. Detectable residual disease at the end of remission induction correlated with adverse genetic abnormalities--the Philadelphia chromosome and MLL gene rearrangements--but not with other presenting features. Detectable leukaemia was associated with subsequent relapse regardless of the time at which bone-marrow samples were examined (p < 0.002 for all comparisons). For example, 3-year cumulative incidence (SE) of relapse in patients with and without detectable leukaemia at remission induction was 32.5% (10.6) and 7.5% (4.0), respectively (p < 0.001); for tests done at week 14, it was 42.1% (14.6) and 6.6% (3.5), p < 0.001. These correlations remained significant after adjusting for adverse presenting features. A higher degree of marrow infiltration by leukaemic cells (> or = 0.1%) in week 14 samples identified a subset of patients with an especially poor prognosis.

INTERPRETATION

Immunological detection of residual leukaemic cells at any point in the treatment course is a powerful predictor of relapse in children with ALL. Alternative treatment should be considered for cases with persistent disease beyond the first 3 months of continuation therapy.

Probability of carrying a mutation of breast-ovarian cancer gene BRCA1 based on family history

BACKGROUND

Heritable mutations of the breast cancer gene BRCA1 are rare, occurring in fewer than 1% of women in the general population, and therefore account for a small proportion of cases of breast and ovarian cancers. Nevertheless, the presence of such mutations is highly predictive of the development of these cancers.

PURPOSE

We developed and applied a mathematic model for calculating the probability that a woman with a family history of breast and/or ovarian cancer carries a mutation of BRCA1.

METHODS AND RESULTS

As a basis for the model, we use Mendelian genetics and apply Bayes' theorem to information on the family history of these diseases. Of importance are the exact relationships of all family members, including both affected and unaffected members, and ages at diagnosis of the affected members and current ages of the unaffected members. We used available estimates of BRCA1 mutation frequencies in the general population and age-specific incidence rates of breast and ovarian cancers in carriers and noncarriers of mutations to estimate the probability that a particular member of the family carries a mutation. This probability is based on cancer statuses of all first- and second-degree relatives. We first describe the model by considering single individuals: a woman diagnosed with breast and/or ovarian cancer and also a woman free of cancer. We next considered two artificial and two actual family histories and addressed the sensitivity of our calculations to various assumptions. Particular relationships of family members with and without cancer can have a substantial impact on the probability of carrying a susceptibility gene. Ages at diagnosis of affected family members and their types of cancer are also important. A woman with two primary cancers can have a probability of carrying a mutation in excess of 80%, even with no other information about family history. The number and relationships of unaffected members, along with their current ages or ages at death, are critical determinants of one's carrier probability. An affected woman with several cancers in her family can have a probability of carrying a mutation that ranges from close to 100% to less than 5%.

CONCLUSION

Our model gives informative and specific probabilities that a particular woman carries a mutation.

IMPLICATIONS

This model focuses on mutations in BRCA1 and assumes that all other breast cancer is sporadic. With the cloning of BRCA2, we now know that this assumption is incorrect. We have adjusted the model to include BRCA2, but the use of this version must await publication of penetrance data for BRCA2, including those for male breast cancer that are apparently associated with BRCA2 but not with BRCA1. The current model is, nevertheless, appropriate and useful. Of principal importance is its potential and that of improved versions for aiding women and their health care providers in assessing the need for genetic testing.

Promising early outcomes with a novel, complete steroid avoidance immunosuppression protocol in pediatric renal transplantation

BACKGROUND

Corticosteroids have been a cornerstone of immunosuppression for four decades despite their adverse side effects. Past attempts at steroid withdrawal in pediatric renal transplantation have had little success. This study tests the hypothesis that a complete steroid-free immunosuppressive protocol avoids steroid dependency for suppression of the immune response with its accompanying risk of acute rejection on steroid withdrawal.

METHODS

An open labeled prospective study of complete steroid avoidance immunosuppressive protocol was undertaken in 10 unsensitized pediatric recipients (ages 5-21 years; mean 14.4 years) of first renal allografts. Steroids were substituted with extended daclizumab use, in combination with tacrolimus and mycophenolate mofetil. Protocol biopsies were performed in the steroid-free group at 0, 1, 3, 6, and 12 months posttransplantation. Clinical outcomes were compared to a steroid-based group of 37 matched historical controls.

RESULTS

Graft and patient survival was 100% in both groups. Clinical acute rejection was absent in the steroid-free group at a mean follow-up time of 9 months (range 3-13.7 months). Protocol biopsies in the steroid-free group (includes 10 patients at 3 months, 7 at 6 months, and 4 at 12 months) revealed only two instances of mild (Banff 1A) subclinical rejection (reversed by only a nominal increase in immunosuppression) and no chronic rejection. At 6 months the steroid-free group had no hypertension requiring treatment (P=0.003), no hypercholesterolemia (P=0.007), and essentially no body disfigurement (P=0.0001). Serum creatinines, Schwartz GFR, and mean delta height Z scores trended better in the steroid-free group. In the steroid-free group, one patient had cytomegalovirus disease at 1 month and three had easily treated herpes simplex stomatitis, but with no significant increase in bacterial infections or rehospitalizations over the steroid-based group. The steroid-free group was more anemic early posttransplantation (P=0.004), suggesting an early role of steroids in erythrogenesis; erythropoietin use normalized hematocrits by 6 months.

CONCLUSIONS

Complete steroid-free immunosuppression is efficacious and safe in this selected group of children with no early clinical acute rejection episodes. This protocol avoids the morbid side effects of steroids without increasing infection, and may play a future critical role in avoiding noncompliance, although optimizing renal function and growth.

Transplantation of microcarrier-attached hepatocytes into 90% partially hepatectomized rats

We previously reported a method of intraperitoneal transplantation of liver cells attached to collagen-coated microcarriers, which resulted in prolonged survival and function of the transplanted cells. In the present study, we evaluated the efficacy of liver cell transplantation in providing metabolic support during acute liver insufficiency induced by 90% partial hepatectomy in rats. Ninety per cent of the liver mass (all lobes except the caudate lobe) was resected, and the rats were provided with 5% dextrose orally ad libitum upon regaining consciousness. This regimen results in severe hypoglycemia and death within 48 hr. When microcarrier-attached liver cells were transplanted into syngeneic and allogeneic recipients 3 days prior to 90% partial hepatectomy, significantly higher blood glucose levels were observed (p less than 0.01), compared to the levels in control rats which received injections of microcarriers, liver cells or medium alone. There was a marked improvement in long-term survival (40% survived longer than 28 days; p less than 0.001) in rats transplanted with microcarriers-attached cells. None of the rats given injections of microcarriers, liver cells or medium alone survived beyond 5 days. When liver cells alone or attached to microcarriers were injected intraperitoneally immediately after 90% partial hepatectomy, all rats became hypoglycemic and died within 48 hr, suggesting that vascularization of the transplant is required for function of the transplanted hepatocytes. The results indicate that intraperitoneal transplantation of microcarrier-attached hepatocytes prior to 90% partial hepatectomy in rats provides acute metabolic support resulting in improved survival.

Prognostic implications of residual disease tumor-infiltrating lymphocytes and residual cancer burden in triple-negative breast cancer patients after neoadjuvant chemotherapy

BACKGROUND

For primary triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NAC), higher pretreatment tumor-infiltrating lymphocytes (TILs) correlates with increased pathologic complete response (pCR) rates, and improved survival. We evaluated the added prognostic value of residual disease (RD) TILs to residual cancer burden (RCB) in predicting survival post-NAC.

PATIENTS AND METHODS

We combined four TNBC NAC patient cohorts who did not achieve pCR. RD TILs were investigated for associations with recurrence-free survival (RFS), and overall survival (OS) using Cox models with stromal TILs as a continuous variable (per 10% increment). The likelihood ratio test was used to evaluate added prognostic value of RD TILs.

RESULTS

A total of 375 RD TNBC samples were evaluable for TILs and RCB. The median age was 50 years, with 62% receiving anthracycline/taxane chemotherapy. The RCB class after NAC was 11%, 50%, and 39% for I, II, and III, respectively. The median RD TIL level was 20% (IQR 10-40). There was a positive correlation between RD TIL levels and CD8+ T-cell density (ρ = 0.41). TIL levels were significantly lower with increasing post-NAC tumor (P = 0.005), nodal stage (P = 0.032), but did not differ by RCB class (P = 0.84). Higher RD TILs were significantly associated with improved RFS (HR: 0.86; 95% CI 0.79-0.92; P < 0.001), and improved OS (HR: 0.87; 95% CI 0.80-0.94; P < 0.001), and remained significant predictors in multivariate analysis (RFS P = 0.032; OS P = 0.038 for OS). RD TILs added significant prognostic value to multivariate models including RCB class (P < 0.001 for RFS; P = 0.021 for OS). The positive prognostic effect of RD TILs significantly differed by RCB class for RFS (PInt=0.003) and OS (PInt=0.008) with a greater magnitude of positive effect observed for RCB class II than class III.

CONCLUSIONS

TIL levels in TNBC RD are significantly associated with improved RFS and OS and add further prognostic information to RCB class, particularly in RCB class II.

Diverse BF recombinants have spread widely since the introduction of HIV-1 into South America

OBJECTIVE

To describe the genetic diversity of HIV-1 in South America by full genome sequencing and analysis.

METHODS

Purified peripheral blood mononuclear cell DNA from HIV-infected individuals in Argentina, Uruguay and Bolivia was used to amplify full HIV-1 genomes. These were sequenced using the ABI 3100 automated sequencer and phylogenetically analysed.

RESULTS

Twenty-one HIV-1 strains from three South American countries, 17 of which were pre-screened by envelope heteroduplex mobility assay (HMA), were studied. Ten out of 10 HMA subtype F and four out of seven HMA subtype B strains were actually BF recombinants upon full genome analysis. Two BF recombinants from Argentina and two from Uruguay had the same structure, representing a new circulating recombinant form termed CRF12_BF(ARMA159). Twelve other BF recombinants had structures related to CRF12 but with additional segments of subtype B; each was unique. BF recombinants were temporally and geographically widespread, found as early as 1986-1987 in vertically infected Argentinian children and in Argentina, Uruguay, and Bolivia.

Prevalence and predictors of depressive, anxiety and substance use disorders in HIV-infected and uninfected men: a longitudinal evaluation

BACKGROUND

There is little agreement on whether the prevalence of psychiatric disorder is elevated in HIV-seropositive (HIV+) populations compared with uninfected persons. However, evaluation of this issue has been limited difficulties of sampling, study design and failure to control for other risk factors for disorder.

METHODS

Prevalence and clinical characteristics of DSM-III-R major depressive disorder (MDD), generalized anxiety disorder, adjustment disorder, and alcohol and substance abuse/dependence were evaluated in a representative sample of HIV+ men attending primary care physicians' offices in a defined geographical area. Lifetime prevalence at baseline and 1-year rates during longitudinal follow-up were determined for the 113 HIV+ men, as well as 57 HIV-men, via standardized interview. Multivariate analyses considered unique and combined effects of HIV serostatus and other risk factors on likelihood of disorder.

RESULTS

Although there were no differences in lifetime rates prior to baseline, HIV+ men were at greater risk for disorders during the prospective study period. For MDD, this effect was maintained even after controlling for other risk factors. Several of these other factors bore their own effects: regardless of HIV serostatus, men were susceptible to psychopathology if at baseline they were younger, had a lifetime psychiatric history, or had poor social supports or a low sense of personal mastery.

CONCLUSIONS

The risk of certain psychiatric disorders appears uniquely elevated in HIV+ men. Since other factors also influence risk, interventions designed to minimize psychopathology during HIV infection should attend to both HIV-related and non-HIV-related risk factors.

Coordinated assembly of multisubunit proteins: oligomerization of bacterial enterotoxins in vivo and in vitro

In this paper we study the assembly, in vivo and in vitro, of a family of hexameric, heat-labile enterotoxins produced by diarrheagenic bacteria. The toxins, which consist of an A subunit and five B subunits, are assembled by a highly coordinated process that ensures secretion of the holotoxin complex. We show that (i) oxidation of cysteine residues in the B subunits is a prerequisite step for in vivo formation of B-subunit pentamers, (ii) reduction of dissociated B subunits in vitro abolishes their ability to reassemble, (iii) the kinetics of B-pentamer assembly in vivo can be mimicked under defined conditions in vitro, (iv) A subunits cannot associate with fully assembled B pentamers in vitro, and (v) A subunits cause an approximately 3-fold acceleration in the rate of B-subunit pentamerization in vivo, implying that A subunits play a coordinating role in the pathway of holotoxin assembly. The last finding is likely to be of general significance, since it provides a mechanism for preferentially excluding or favoring certain intermediates in the assembly of multisubunit proteins.

Recombinant system for overexpression of cholera toxin B subunit in Vibrio cholerae as a basis for vaccine development

We have constructed an overexpression system in which the gene encoding the B subunit of cholera toxin (CTB) was placed under the control of the strong tacP promoter in a wide host range plasmid. Recombinant nontoxigenic classical and E1 Tor Vibrio cholerae strains of different serotypes harboring this plasmid excreted 10- to 100-fold higher amounts of CTB than any other wild-type or recombinant strain tested and may therefore be useful killed oral vaccine strains. The manipulations to place the CTB gene under tacP also included, by design, the introduction of single enzyme restriction sites for gene fusions to the CTB amino terminus. Cloning into these sites allows construction of CTB-derived hybrid proteins carrying various putative vaccine peptide antigens.

Mechanism of toxin secretion by Vibrio cholerae investigated in strains harboring plasmids that encode heat-labile enterotoxins of Escherichia coli

A genetically engineered Vibrio cholerae strain from which the cholera toxin genes had previously been deleted was used as a host in which to study the expression and secretion of related toxins and their subunits. Recombinant plasmids encoding heat-labile enterotoxins (LTs) from Escherichia coli of human and porcine origin were expressed in the V. cholerae host, and this resulted in the secretion of the LTs into the extracellular milieu. The secreted LTs were isolated and it was found that the A subunits of human and porcine LT were "unnicked" polypeptides, which indicates that nicking is not obligatory for toxin secretion. V. cholerae strains were also constructed that harbored plasmids encoding either the A or the B subunits of human LT (A+B-, or A-B+). Approximately 90% of the B subunits were secreted from the A-B+ strain, while all of the A subunits expressed by the A+B- strain remained cell associated. This implies that strains synthesizing both subunits assemble the A and B subunits prior to their secretion. We propose that the entry of the toxin into the secretory step of the export pathway is mediated by a secretory apparatus that recognizes structural domains within the B subunit of LT.

Phase 2 trial of WR6026, an orally administered 8-aminoquinoline, in the treatment of visceral leishmaniasis caused by Leishmania chagasi

There are no recognized orally administered treatments for any of the leishmaniases. The 8-aminoquinoline WR6026 is an orally administered analog of primaquine that cured 50% of patients with kala-azar in Kenya at a dose of 1 mg/kg/day for 28 days. A further phase 2, open-label, dose-escalating safety and efficacy study was performed for kala-azar in Brazil. Cure rates for Brazilian patients treated for 28 days were as follows: 1 mg/kg/day: 0 of 4 (0%); 1.5 mg/kg/day: 1 of 6 (17%); 2.0 mg/kg/day: 4 of 6 (67%); 2.5 mg/kg/day: 1 of 5 (20%); and 3.25 mg/kg/day: 0 of 1 (0%). Nephrotoxicity that was not anticipated from preclinical animal studies or from phase 1 studies was seen at 2.5 mg/kg/day in 2 patients and in the single patient administered 3.25 mg/kg/day. WR6026 demonstrated the unusual clinical features of lack of increased efficacy against Brazilian kala-azar with increased dosing above 2 mg/kg/day and toxicity that was not present in previous investigations.

Interactions of Bacillus thuringiensis crystal proteins with the midgut epithelial cells of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Binding of different Bacillus thuringiensis insecticidal crystal proteins (ICPs) to the midgut epithelium of Spodoptera frugiperda larvae was characterized by binding experiments with midgut tissue sections and isolated brush border membrane vesicles. Our results show that ICPs interact with the microvilli of epithelial cells of S. frugiperda in two different ways. The first is typical of highly toxic proteins (like CryIC and CryID); this interaction is saturable and specific. In contrast, some nontoxic proteins (like CryIAb) interact nonspecifically with the microvilli, since the binding of this toxin is not affected by the presence of high concentrations of homologous competitor. The CryIC toxin binds to two brush border proteins of 40 and 44 kDa and the CryIAb toxin binds to a single protein of 150 kDa. Immunological detection of ingested B. thuringiensis ICPs on gut sections of S. frugiperda larvae revealed that CryIC and CryID toxins bound along the epithelial brush border microvilli membrane. Binding of the nontoxic protein CryIAb was also observed in the epithelial brush border membrane of fed larvae, but it was extremely weak, implying that this type of interaction occurs also in vivo although it is not related to toxicity.

Dust and airborne exposure to allergens derived from cockroach (Blattella germanica) in low-cost public housing in Strasbourg (France)

BACKGROUND

Although a strong association between allergy to cockroach (CR) and asthma has been observed in the United States and Asia, there are little data about the extent of exposure to CR allergen in Europe.

OBJECTIVE

To determine the levels of CR allergens in dust samples from apartments in Strasbourg and to determine the concentration and size of CR allergens in the air.

METHODS

Nine apartments in a public housing complex were chosen on the basis of visual evidence of CR infestation. Levels of CR allergens (Bla g 1 and Bla g 2) in kitchen and mattress dust samples were measured by immunoassay with the use of monoclonal antibodies. Air was sampled for 3 to 8 hours in the kitchen under undisturbed conditions, during artificial disturbance, and during normal domestic activity by using an impinger and a parallel glass fiber filter and at flow rates of 2 to 20 L/min. Airborne CR and mite allergens were measured concurrently in the bedroom of one apartment before, during, and after artificial disturbance.

RESULTS

High levels of Bla g 1 and Bla g 2 were found in kitchen dust from the nine apartments (geometric means of 3919 U/gm [range 530 to 14306 U/gm] and 497 U/gm [range 73 to 1946 U/gm], respectively). Under undisturbed conditions, airborne CR allergens were not detectable in any of the apartments. During vigorous artificial disturbance, Bla g 1 and Bla g 2 were detectable in air samples from seven apartments (geometric means of 4.5 U/m3 [range 0.7 to 17.2 U/m3] and 1.0 U/m3 [range 0.4 to 3.4 U/m3], respectively). Both allergens were predominantly collected on the first stage of the impinger, and 76% to 80% of the airborne allergen was associated with particles greater than 10 microns in diameter. The levels were significantly higher than those collected on the second or third stages of the impinger (p < 0.001). A comparison of the levels of mite and CR allergens showed that the airborne properties of these allergens were similar, that is, measurable only during disturbance and not detectable 30 minutes after disturbance.

CONCLUSION

Levels of CR allergen in low-cost public housing in Strasbourg can be as high as or higher than the levels measured in towns in the United States. CR allergens become airborne during disturbance and are primarily associated with particles greater than 10 microns in diameter. Patients with asthma living in urban areas of Europe in housing prone to CR infestation should be evaluated for sensitization and exposure to CR allergens.

Biophysical characterization of zinc ejection from HIV nucleocapsid protein by anti-HIV 2,2'-dithiobis[benzamides] and benzisothiazolones

HIV nucleocapsid protein (NCp7) has been suggested as a possible target for 2,2'-dithiobis-[benzamide] and benzisothiazolone agents that inhibit viral replication in infected cells (Rice et al. Science 1995, 270, 1194-1197). The solution behavior of these compounds and the mechanistic events leading to removal of Zn from HIV nucleocapsid protein in vitro has been studied by electrospray ionization mass spectrometry, 500 MHz one- and two-dimensional nuclear magnetic resonance spectroscopy, and circular dichroism spectroscopy. We demonstrate that (1) Zn ejection is accompanied by formation of covalent complexes formed between the 2,2'-dithiobis[benzamide] monomers and Cys residues of Zn-depleted NCp7, (2) the rate of Zn ejection is faster for the C-terminal Zn finger and slower for the N-terminal finger, (3) Zn ejection results in a loss of structural integrity of the NCp7 protein, and (4) there is no appreciable interaction between a nonreactive isostere of the lead 2,2'-dithiobis[benzamide] and NCp7 in buffered aqueous solution. These findings are discussed in terms of the mechanism of action of Zn ejection by aromatic 2,2'-dithiobis[benzamides].

Mithramycin selectively inhibits transcription of G-C containing DNA

Mithramycin induces a reversible inhibition of cellular RNA synthesis without affecting DNA synthesis. The authors have shown this drug induces myeloid differentiation of HL-60 promyelocytic leukemia cells and is an effective agent in certain patients with chronic granulocytic leukemia. In order to investigate the mechanism by which this drug inhibits RNA synthesis we have compared the effect of mithramycin on RNA synthesis by whole cells, isolated nuclei, and RNA synthesis by isolated E. coli RNA polymerase and eukaryotic RNA polymerase II. Exposure of HL-60 cells to mithramycin at concentrations of 4.6 X 10(-7) m or higher for 48 hours causes an almost immediate inhibition of RNA synthesis (up to 85% at 4 hours) with only modest cytotoxicity at these concentrations. Endogenous RNA synthesis by isolated nuclei can be inhibited by mithramycin only at high concentrations (greater than 10(-5) m), suggesting that mithramycin primarily may inhibit initiation, rather than elongation. Mithramycin inhibits in vitro transcription of salmon sperm DNA by E. coli RNA polymerase at DNA:drug ratios similar to those required for RNA synthesis inhibition in whole cells. Similar DNA binding studies with synthetic oligonucleotides demonstrate that mithramycin is a potent inhibitor of transcription of Poly dG.dC by E. coli RNA polymerase but has no effect on transcription of Poly dA.dT. The rapid inhibition of whole cell and isolated RNA polymerase transcription, and the relative insensitivity of isolated nuclei, suggest mithramycin may interact with specific DNA sequences in order to inhibit the initiation of RNA synthesis in intact cells.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Basal ganglia surface morphology and the effects of stimulant medications in youth with attention deficit hyperactivity disorder

OBJECTIVE

Disturbances in the basal ganglia portions of cortico-striato-thalamo-cortical circuits likely contribute to the symptoms of attention deficit hyperactivity disorder (ADHD). The authors examined the morphologic features of the basal ganglia nuclei (caudate, putamen, and globus pallidus) in children with ADHD.

METHOD

A total of 104 individuals (combined-type ADHD patients: N=47; healthy comparison subjects: N=57), aged 7 to 18 years, were examined in a cross-sectional case-control study using anatomical magnetic resonance imaging. Conventional volumes and the surface morphology for the basal ganglia were measured.

RESULTS

Overall volumes were significantly smaller only in the putamen. Analysis of the morphological surfaces revealed significant inward deformations in each of the three nuclei, localized primarily in portions of these nuclei that are components of limbic, associative, and sensorimotor pathways in the cortico-striato-thalamo-cortical circuits in which these nuclei reside. The more prominent these inward deformations were in the patient group, the more severe the ADHD symptoms. Surface analyses also demonstrated significant outward deformations of all basal ganglia nuclei in the ADHD children treated with stimulants compared with those ADHD youth who were untreated. These stimulant-associated enlargements were in locations similar to the reduced volumes detected in the ADHD group relative to the comparison group. The outward deformations associated with stimulant medications attenuated the statistical effects of the primary group comparisons.

CONCLUSIONS

These findings potentially represent evidence of anatomical dysregulation in the circuitry of the basal ganglia in children with ADHD and suggest that stimulants may normalize morphological features of the basal ganglia in children with the disorder.

Diagnostic subgroups of affective disorders and their urinary excretion of catecholamine metabolities

Previous reports have indicated that some depressed patients excrete less than normal quantities of 3-methoxy-4-hydroxyphenyl glycol (MHPG). The authors present data indicating that a subgroup of depressed patients who excrete less than normal quantities of MHPG may be identified by the application of explicit clinical criteria. They found no significant difference in the excretion of normetanephrine (NM), metanephrine (M), and 3-methoxy-4-hydroxymandelic acid (VMA) among any of the diagnostic subgroups or between each patient group and a healthy comparison group. However, depressed patients diagnosed as having primary affective disorder and bipolar illness excreted significantly less MHPG than did the healthy comparison group.

High altitude tissue adaptation in Andean coots: capillarity, fibre area, fibre type and enzymatic activities of skeletal muscle

Capillarity, fibre types, fibre area and enzyme activities of different skeletal muscles (pectoralis, extensor digitorum longus), tibialis anterior, plantaris and the myocardium) were compared in Andean coot (Fulica americana peruviana) native to high altitude (Junín, Perú, 4200 m) and the same species nesting at sea level. Numbers of capillaries per square millimeter were higher in all high-altitude muscles when compared with sea-level muscles (P < 0.0001). Moreover, values for capillaries per fibre and capillaries in contact with each fibre were higher in digitorum and tibialis high-altitude muscles. Muscle fibres were classified as Type I, Type IIA or Type IIB on the basis of their myofibrillar ATPase pH lability. Pectoralis muscle of high-altitude and sea-level coots presented only fibres of Type IIA. In contrast, all the leg muscles studied showed a mosaic pattern of the three fibre types. Fibre areas were determined using a Leitz Texture Analysis System. Significant differences in fibre area were observed (P < 0.01) between high-altitude and sea-level muscles. Mean muscle fibre diameters were also lower in the high-altitude group than in the sea-level group. The enzyme activities studied were hexokinase, lactate dehydrogenase, citrate synthase and 3-hydroxyacyl-CoA-dehydrogenase. The oxidative capacity, as reflected by citrate synthetase and hydroxyacyl-CoA-dehydrogenase activities, was greater for myocardial and pectoralis than for leg muscles. However, analysis of maximal enzyme activities showed that there were no significant differences between the glycolytic and oxidative enzyme activities of high-altitude and sea-level coots.(ABSTRACT TRUNCATED AT 250 WORDS)