Chronotype, Time of Day, and Children's Cognitive Performance in Remote Neuropsychological Assessment

Research on the influence of chronotype and time of day (TOD) on cognitive performance, especially in children, is limited. We explored potential interactive effects, hypothesizing that performance differs when comparing preferred vs. non-preferred TOD. In total, 76 morning-type (MT = 37) or evening-type (ET = 39) children from the third and fourth grades (48.7% girls; M age = 8.05; SD age = 0.51), identified through the Children Chronotype Questionnaire, completed two 30-min neuropsychological assessment sessions via videoconference on the first (9:00) or last hour (16:00) of the school day. The protocol included neuropsychological tests targeting memory, language, and attention/executive domains. The results revealed an interactive effect of medium size between chronotype and TOD on a Rapid Alternating Stimulus (Naming) Task. MT and ET performed faster in asynchrony conditions (morning for ET; afternoon for MT). Additionally, ET outperformed MT in a Backward Digit Span Task, irrespective of TOD. TOD also influenced performance on an Alternating Verbal Fluency Task, with both MT and ET children performing better in the morning. These results underscore the importance of chronotype and TOD in children's cognitive performance, particularly in working memory and verbal fluency. Children assessed during non-preferred TOD exhibited better performance on some cognitive tasks, challenging the assumption that optimal times always yield superior results.

A multivariate multilevel approach to unravel the associations between individual and school factors on children's motor performance in the REACT project

OBJECTIVE

The aim was to (1) estimate the relationship between physical fitness (PF) and object control fundamental movement skills (FMS), (2) identify child characteristics that relate with PF and FMS, and (3) examine associations between the school environment, PF, and FMS.

METHODS

The sample included 1014 Portuguese children aged 6-10 years from the REACT project. PF was assessed via running speed, shuttle run, standing long jump, handgrip, and the PACER test. Object control FMS were assessed with stationary dribble, kick, catch, overhand throw, and underhand roll. Test performances were transformed into z-scores, and their sum was expressed as overall PF and FMS. Child-level variables included body mass index (BMI) z-scores, accelerometer-measured sedentary time and moderate-to-vigorous physical activity, and socioeconomic status (SES). School size, physical education classes, practice areas, and equipment were also assessed.

RESULTS

Approximately, 90% of the variance in object control PF and FMS was at the child level, and 10% at the school level. The correlation between PF and object control FMS was .62, which declined to .43 with the inclusion of covariates. Older, more active, and higher SES children had higher object control PF and FMS, and boys outperformed girls. BMI was negatively associated with PF but not with object control FMS. Sedentary time and number of physical education classes were not significant predictors. Most school predictors did not jointly associate with PF and object control FMS.

CONCLUSION

PF and object control FMS z-scores were moderately related. Not all child characteristics were associated with both PF and object control FMS, and their effect sizes were different. School characteristics only explained 10% of the total variation in PF and object control FMS.

In vitro activity of cefiderocol and other newly approved antimicrobials against multi-drug resistant Gram-negative pathogens recovered in intensive care units in Spain and Portugal

OBJECTIVE

The antimicrobial resistance is a significant public health threat, particularly for healthcare-associated infections caused by carbapenem-resistant Gram-negative pathogens which are increasingly reported worldwide. The aim of this study was to provide data on the in vitro antimicrobial activity of cefiderocol and that of commercially available comparator antibiotics against a defined collection of recent clinical multi-drug resistant (MDR) microorganisms, including carbapenem resistant Gram-negative bacteria collected from different regions in Spain and Portugal.

METHODS

A total of 477 clinical isolates of Enterobacterales, Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia were prospectively (n=265) and retrospectively (n=212) included (2016-2019). Susceptibility testing was performed using standard broad microdilution and results were interpreted using CLSI-2021 and EUCAST-2021 criteria.

RESULTS

Overall, cefiderocol showed a good activity against Enterobacterales isolates, being 99.5% susceptible by CLSI and 94.5% by EUCAST criteria. It also demonstrated excellent activity against P. aeruginosa and S. maltophilia isolates, all being susceptible to this compound considering CLSI breakpoints. Regarding A. baumannii (n=64), only one isolate was resistant to cefiderocol.

CONCLUSIONS

Our results are in agreement with other studies performed outside Spain and Portugal highlighting its excellent activity against MDR gram-negative bacteria. Cefiderocol is a therapeutic alternative to those available for the treatment of infections caused by these MDR bacteria.

Application of Covalent Organic Frameworks (COFs) as Dyes and Additives for Dye-Sensitized Solar Cells (DSSCs)

Five Covalent Organic Frameworks (COFs) were synthesized and applied to Dye-Sensitized Solar Cells (DSSCs) as dyes and additives. These porous nanomaterials are based on cheap, abundant commercially available ionic dyes (thionin acetate RIO-43, Bismarck brown Y RIO-55 and pararosaniline hydrochloride RIO-70), and antibiotics (dapsone RIO-60) are used as building blocks. The reticular innovative organic framework RIO-60 is the most promising dye for DSSCs. It possesses a short-circuit current density (J_sc) of 1.00 mA/cm², an open-circuit voltage (V_oc) of 329 mV, a fill factor (FF) of 0.59, and a cell efficiency (η) of 0.19%. These values are higher than those previously reported for COFs in similar devices. This first approach using the RIO family provides a good perspective on its application in DSSCs as a dye or photoanode dye enhancer, helping to increase the cell's lifespan.

In vitro activity of imipenem/relebactam against Pseudomonas aeruginosa isolates recovered from ICU patients in Spain and Portugal (SUPERIOR and STEP studies)

OBJECTIVES

To study the in vitro activity of imipenem/relebactam and comparators and the imipenem/relebactam resistance mechanisms in a Pseudomonas aeruginosa collection from Portugal (STEP, 2017-18) and Spain (SUPERIOR, 2016-17) surveillance studies.

METHODS

P. aeruginosa isolates (n = 474) were prospectively recovered from complicated urinary tract (cUTI), complicated intra-abdominal (cIAI) and lower respiratory tract (LRTI) infections in 11 Portuguese and 8 Spanish ICUs. MICs were determined (ISO broth microdilution). All imipenem/relebactam-resistant P. aeruginosa isolates (n = 30) and a subset of imipenem/relebactam-susceptible strains (n = 32) were characterized by WGS.

RESULTS

Imipenem/relebactam (93.7% susceptible), ceftazidime/avibactam (93.5% susceptible) and ceftolozane/tazobactam (93.2% susceptible) displayed comparable activity. The imipenem/relebactam resistance rate was 6.3% (Portugal 5.8%; Spain 8.9%). Relebactam restored imipenem susceptibility to 76.9% (103/134) of imipenem-resistant isolates, including MDR (82.1%; 32/39), XDR (68.8%; 53/77) and difficult-to-treat (DTR) isolates (67.2%; 45/67). Among sequenced strains, differences in population structure were detected depending on the country: clonal complex (CC)175 and CC309 in Spain and CC235, CC244, CC348 and CC253 in Portugal. Different carbapenemase gene distributions were also found: VIM-20 (n = 3), VIM-1 (n = 2), VIM-2 (n = 1) and VIM-36 (n = 1) in Spain and GES-13 (n = 13), VIM-2 (n = 3) and KPC-3 (n = 2) in Portugal. GES-13-CC235 (n = 13) and VIM type-CC175 (n = 5) associations were predominant in Portugal and Spain, respectively. Imipenem/relebactam showed activity against KPC-3 strains (2/2), but was inactive against all GES-13 producers and most of the VIM producers (8/10). Mutations in genes affecting porin inactivation, efflux pump overexpression and LPS modification might also be involved in imipenem/relebactam resistance.

CONCLUSIONS

Microbiological results reinforce imipenem/relebactam as a potential option to treat cUTI, cIAI and LRTI caused by MDR/XDR P. aeruginosa isolates, except for GES-13 and VIM producers.

Effect of Iodide-Based Organic Salts and Ionic Liquid Additives in Dye-Sensitized Solar Cell Performance

The use of ionic liquid and organic salts as additives for electrolyte systems in dye-sensitized solar cells have been widely described in recent years. The tunability of their physical-chemical properties according to the cation-anion selection contributes toward their high efficiencies. For this purpose, several iodide-based organic salts including imidazolium, picolinium, guanidinium and alkylammonium cations were tested using acetonitrile/valeronitrile electrolytes and their photovoltaic parameters were compared. A best efficiency of 4.48% (4.15% for the reference) was found for 1-ethyl-2,3-dimethylimidazolium iodide ([C2DMIM]I) containing electrolyte, reaffirming the effectiveness of these additives. 4-tertbutylpyridine was included into the formulation to further improve the performance while determining which iodide salts demonstrate the highest synergy with this additive. [C2DMIM]I once again proved to be the superior additive, achieving an efficiency of 6.48% (6% for the reference). Electrochemical impedance spectroscopy was employed to elucidate the effects of the various additives, demonstrating the relevance of the counter electrode resistance on device performance. Finally, several computational descriptors for the cationic structures were calculated and correlated with the photovoltaic and resistance parameters, showing that properties related to polarity, namely relative positive charge, molecular polarizability and partition coefficient are in good agreement with the counter-electrode resistance.

Ambipolar pentacyclic diamides with interesting electrochemical and optoelectronic properties

Developing organic semiconductors for organic thin film transistors (OTFT) and optoelectronic applications is a challenge. We developed highly crystalline pentacyclic diimides (3) and (4) which showed good OTFT and OLED potential and energy gaps of 2.60 eV and 2.54 eV. They exhibited interesting photo and eletroluminescence activity. Both compounds showed good quantum yields (0.56 for (3) and 0.60 for (4)).

SARS-CoV-2 infection in kidney transplant recipients: Early report of five cases

From December 2019 to March 2020, China was the epicenter of the SARS‐CoV‐2 infection pandemic, but from that moment on, Europe surpassed China in the number of new cases and deaths related to this novel viral respiratory infection. The emergence of this world pandemic is particularly important for solid organ transplant recipients, who might have an increased risk of mortality, not only due to their chronic immunosuppression status, but also to the cardiovascular risk that correlates with several years of chronic kidney disease. To the extent that there is still a lack of knowledge about the clinical characteristics, evolution, and prognosis of SARS‐CoV‐2 infection in kidney transplant recipients, we will report the first 5 cases diagnosed and followed in our transplant unit, as well as share the therapeutic strategies adopted.

A pseudorotaxane formed from a cucurbit[7]uril wheel and a bioinspired molecular axle with pH, light and redox-responsive properties

A pH-, light- and redox-responsive flavylium-bipyridinium molecular dyad (bioinspired in natural anthocyanins) was synthesized and employed to devise a pseudorotaxane with the macrocycle cucurbit[7]uril (CB7) in aqueous solution. The inclusion complex was characterized by UV-Vis absorption, fluorescence emission, NMR and electrochemical techniques which demonstrate formation of a stable binary complex between the dyad and CB7 both under acidic and neutral conditions. It is noteworthy that the flavylium-bipyridinium tricationic dyad is only stable in highly acidic media, undergoing a reversible hydration reaction at slightly acidic or neutral pH to give a trans-chalcone-bipyridinium dication. 1H NMR experiments showed that in this last species the CB7 binds to the bipyridinium unit while in the tricationic species the macrocycle is positioned between the flavylium and the bipyridinium moieties. The different location of the CB7 wheel in the two dyad states allows control of the shuttling movement using light and pH stimuli that trigger the interconversion between these two species.

N-Heterocyclic Olefin Catalysis for the Ring Opening of Cyclic Amidine Compounds: A Pathway to the Synthesis of ε-Caprolactam- and γ-Lactam-Derived Amines

For the first time, 1,2-dimethyl-3-ethylimidazolium iodide (1a) catalyzes the ring opening of the bicyclic amidine system of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or DBN (1,5-diazabicyclo[4.3.0]non-5-ene) on reaction with aldehydes. The mechanism here proposed involves an N-heterocyclic olefin (NHO) catalytic species that acts as a nucleophile to promote the cyclic amidine ring opening. The resulting ε-caprolactam- and γ-lactam-derived imines were obtained in moderate to excellent yields (28-99%) and reduced to the corresponding amines by sodium borohydride. Confirmation of the imine product was achieved via single-crystal X-ray diffraction studies.

A 2.5 mW/ch, 50 Mcps, 10-Analog Channel, Adaptively Biased Read-Out Front-End IC With Low Intrinsic Timing Resolution for Single-Photon Time-of-Flight PET Applications With Time-Dependent Noise Analysis in 90 nm CMOS

This paper presents a 10-channel time-of-flight application-specific integrated circuit (ASIC) for positron emission tomography in a 90 nm standard CMOS process. To overcome variations in channel-to-channel timing resolution caused by mismatch and process variations, adaptive biases and a digital-to-analog converter (DAC) are utilized. The main contributions of this work are as follows. First, multistage architectures reduce the total power consumption, and detection bandwidths of analog preamplifiers and comparators are increased to 1 and 1.5 GHz, respectively, relative to those in previous studies. Second, a total intrinsic electronic timing resolution of 9.71 ps root-mean-square (RMS) is achieved (13.88 ps peak and 11.8 ps average of the 10 channels in 5 ASICs). Third, the proposed architecture reduces variations in channel-to-channel timing resolution to 2.6 bits (equivalent to 4.17 ps RMS) by calibrating analog comparator threshold levels. A 181.5 ps full-width-at-half-maximum timing resolution is measured with an avalanche photo diode and a laser setup. The power consumption is 2.5 mW using 0.5 and 1.2 V power supplies. The proposed ASIC is implemented in a 90 nm TSMC CMOS process with a total area of 3.3 mm × 2.7 mm.

A thermochromic europium(iii) room temperature ionic liquid with thermally activated anion–cation interactions

An observable and reversible case of thermochromism due to an unusual interaction between the countercation and the ligand of an europium(iii) tetrakis-β-diketonate room temperature ionic liquid is reported.

The role of epigenetic modifiers in extended cultures of functional hepatocyte-like cells derived from human neonatal mesenchymal stem cells

The development of predictive in vitro stem cell-derived hepatic models for toxicological drug screening is an increasingly important topic. Herein, umbilical cord tissue-derived mesenchymal stem cells (hnMSCs) underwent hepatic differentiation using an optimized three-step core protocol of 24 days that mimicked liver embryogenesis with further exposure to epigenetic markers, namely the histone deacetylase inhibitor trichostatin A (TSA), the cytidine analogue 5-azacytidine (5-AZA) and dimethyl sulfoxide (DMSO). FGF-2 and FGF-4 were also tested to improve endoderm commitment and foregut induction during Step 1 of the differentiation protocol, being HHEX expression increased with FGF-2 (4 ng/mL). DMSO (1%, v/v) when added at day 10 enhanced cell morphology, glycogen storage ability, enzymatic activity and induction capacity. Moreover, the stability of the hepatic phenotype under the optimized differentiation conditions was examined up to day 34. Our findings showed that hepatocyte-like cells (HLCs) acquired the ability to metabolize glucose, produce albumin and detoxify ammonia. Global transcriptional analysis of the HLCs showed a partial hepatic differentiation degree. Global analysis of gene expression in the different cells revealed shared expression of gene groups between HLCs and human primary hepatocytes (hpHeps) that were not observed between HepG2 and hpHeps. In addition, bioinformatics analysis of gene expression data placed HLCs between the HepG2 cell line and hpHeps and distant from hnMSCs. The enhanced hepatic differentiation observed was supported by the presence of the hepatic drug transporters OATP-C and MRP-2 and gene expression of the hepatic markers CK18, TAT, AFP, ALB, HNF4A and CEBPA; and by their ability to display stable UGT-, EROD-, ECOD-, CYP1A1-, CYP2C9- and CYP3A4-dependent activities at levels either comparable with or even higher than those observed in primary hepatocytes and HepG2 cells. Overall, an improvement of the hepatocyte-like phenotype was achieved for an extended culture time suggesting a role of the epigenetic modifiers in hepatic differentiation and maturation and presenting hnMSC-HLCs as an advantageous alternative for drug discovery and in vitro toxicology testing.

Estrogen promotes the brain metastatic colonization of triple negative breast cancer cells via an astrocyte-mediated paracrine mechanism

Brain metastases (BM) are a devastating consequence of breast cancer. BM occur more frequently in patients with estrogen receptor-negative (ER−) breast cancer subtypes; HER2 overexpressing (HER2+) tumors and triple-negative (TN) (ER−, progesterone receptor-negative (PR−) and normal HER2) tumors. Young age is an independent risk factor for development of BM, thus we speculated that higher circulating estrogens in young, pre-menopausal women could exert paracrine effects through the highly estrogen-responsive brain microenvironment. Using a TN experimental metastases model, we demonstrate that ovariectomy decreased the frequency of MRI detectable lesions by 56% as compared to estrogen supplementation, and that the combination of ovariectomy and letrozole further reduced the frequency of large lesions to 14.4% of the estrogen control. Human BM expressed 4.2-48.4% ER+ stromal area, particularly ER+ astrocytes. In vitro, E2-treated astrocytes increased proliferation, migration and invasion of 231BR-EGFP cells in an ER-dependent manner. E2 upregulated EGFR ligands Egf, Ereg, and Tgfa mRNA and protein levels in astrocytes, and activated EGFR in brain metastatic cells. Co-culture of 231BR-EGFP cells with E2-treated astrocytes led to upregulation of the metastatic mediator S100 Calcium-binding protein A4 (S100A4) (1.78-fold, P<0.05). Exogenous EGF increased S100A4 mRNA levels in 231BR-EGFP cells (1.40±0.02 fold, P<0.01 compared to vehicle-control) and an EGFR/HER2 inhibitor blocked this effect, suggesting that S100A4 is a downstream effector of EGFR activation. ShRNA-mediated S100A4 silencing in 231BR-EGFP cells decreased their migration and invasion in response to E2-CM, abolished their increased proliferation in co-cultures with E2-treated astrocytes, and decreased brain metastatic colonization. Thus, S100A4 is one effector of the paracrine action of E2 in brain metastatic cells. These studies provide a novel mechanism by which estrogens, acting through ER+ astrocytes in the brain microenvironment, can promote BM of TN breast cancers, and suggests existing endocrine agents may provide some clinical benefit towards reducing and managing BM.

Spatiotemporal control over the co-conformational switching in pH-responsive flavylium-based multistate pseudorotaxanes

A multistate molecular dyad containing flavylium and viologen units was synthesized and the pH dependent thermodynamics of the network completely characterized by a variety of spectroscopic techniques such as NMR, UV-vis and stopped-flow. The flavylium cation is only stable at acidic pH values. Above pH ≈ 5 the hydration of the flavylium leads to the formation of the hemiketal followed by ring-opening tautomerization to give the cis-chalcone. Finally, this last species isomerizes to give the trans-chalcone. For the present system only the flavylium cation and the trans-chalcone species could be detected as being thermodynamically stable. The hemiketal and the cis-chalcone are kinetic intermediates with negligible concentrations at the equilibrium. All stable species of the network were found to form 1 : 1 and 2 : 1 host : guest complexes with cucurbit[7]uril (CB7) with association constants in the ranges 10(5)-10(8) M(-1) and 10(3)-10(4) M(-1), respectively. The 1 : 1 complexes were particularly interesting to devise pH responsive bistable pseudorotaxanes: at basic pH values (≈12) the flavylium cation interconverts into the deprotonated trans-chalcone in a few minutes and under these conditions the CB7 wheel was found to be located around the viologen unit. A decrease in pH to values around 1 regenerates the flavylium cation in seconds and the macrocycle is translocated to the middle of the axle. On the other hand, if the pH is decreased to 6, the deprotonated trans-chalcone is neutralized to give a metastable species that evolves to the thermodynamically stable flavylium cation in ca. 20 hours. By taking advantage of the pH-dependent kinetics of the trans-chalcone/flavylium interconversion, spatiotemporal control of the molecular organization in pseudorotaxane systems can be achieved.

Switchable electrochromic devices based on disubstituted bipyridinium derivatives

Gel switchable electrochromic devices based on disubstituted bipyridinium derivatives have been developed.

Effects of umbilical cord tissue mesenchymal stem cells (UCX®) on rat sciatic nerve regeneration after neurotmesis injuries

Peripheral nerves have the intrinsic capacity of self-regeneration after traumatic injury but the extent of the regeneration is often very poor. Increasing evidence demonstrates that mesenchymal stem/stromal cells (MSCs) may play an important role in tissue regeneration through the secretion of soluble trophic factors that enhance and assist in repair by paracrine activation of surrounding cells. In the present study, the therapeutic value of a population of umbilical cord tissue-derived MSCs, obtained by a proprietary method (UCX^®), was evaluated on end-to-end rat sciatic nerve repair. Furthermore, in order to promote both, end-to-end nerve fiber contacts and MSC cell-cell interaction, as well as reduce the flush away effect of the cells after administration, a commercially available haemostatic sealant, Floseal^®, was used as vehicle. Both, functional and morphologic recoveries were evaluated along the healing period using extensor postural thrust (EPT), withdrawal reflex latency (WRL), ankle kinematics analysis, and either histological analysis or stereology, in the hyper-acute, acute and chronic phases of healing. The histological analysis of the hyper-acute and acute phase studies revealed that in the group treated with UCX^® alone the Wallerian degeneration was improved for the subsequent process of regeneration, the fiber organization was higher, and the extent of fibrosis was lower. The chronic phase experimental groups revealed that treatment with UCX^® induced an increased number of regenerated fibers and thickening of the myelin sheet. Kinematics analysis showed that the ankle joint angle determined for untreated animals was significantly different from any of the treated groups at the instant of initial contact (IC). At opposite toe off (OT) and heel rise (HR), differences were found between untreated animals and the groups treated with either uCx^® alone or UCX^® administered with Floseal^®. Overall, the UCX^® application presented positive effects in functional and morphologic recovery, in both the acute and chronic phases of the regeneration process. Kinematics analysis has revealed positive synergistic effects brought by Floseal^® as vehicle for MSCs.

Manipulation of culture conditions for BHK cell growth inhibition by IRF-1 activation

The activation of interferon-regulatory-factor-1 (IRF-1) hasbeen applied to regulate the cell growth of BHK cells. Theconstitutively expressed IRF-1-estrogen receptor fusion protein(IRF-1-hER) activated by the addition to the culture medium ofan estrogen analogue (estradiol), enabled IRF-1 to gain itstranscriptional activator function. By using a dicistronicstabilised self-selecting construct it was possible to controlcell proliferation. With the addition of 100 nM of estradiol at the beginning of the exponential phase, the IRF-1 activationled to a rapid cell growth inhibition. Two days after estradioladdition cell concentration was still maintained but a decreasein cell viability was observed. This cell response isindependent on clone (producer and non-producer) and culturesystem (static and stirred cultures). Specificrecombinant-protein productivity of the producer clone was notsignificantly altered. Control experiments confirmed that IRF-1activation effect was not due to the addition of estradiol per se, estradiol solvent or serum concentration. The extent ofcell growth inhibition is dependent on estradiol concentrationand estradiol addition time, although a decrease in cellviability was always observed. Reducing the time span ofestradiol exposure allowed the decrease in the cell viability tobe controlled and the stationary inhibited phase to be extended:when the time of contact between the cells and estradiol isreduced cell viability increases, archieving values similar tothose obtained if no estradiol is added. During this recoveryphase the cells passed two different phases: first a stationaryphase extension where cell growth was still inhibited, followedby an increase of cell concentration. The IRF-1 system isreversible. This pattern can be repeated for an extended period when estradiol addition and removal are repeated, showing acyclic response. Thus, it is possible to modulate the IRF-1effect by manipulating cycles of addition/removal of estradioland in this way the stationary phase can be maintained.

Dynamic role of kallikrein 6 in traumatic spinal cord injury

Kallikrein 6 (K6) is a member of the kallikrein gene family that comprises 15 structurally and functionally related serine proteases. In prior studies we showed that, while this trypsin-like enzyme is preferentially expressed in neurons and oligodendroglia of the adult central nervous system (CNS), it is up-regulated at sites of injury due to expression by infiltrating immune and resident CNS cells. Given this background we hypothesized that K6 is a key contributor to the pathophysiology of traumatic spinal cord injury (SCI), influencing neural repair and regeneration. Examination of K6 expression following contusion injury to the adult rat cord, and in cases of human traumatic SCI, indicated significant elevations at acute and chronic time points, not only at the injury site but also in cord segments above and below. Elevations in K6 were particularly prominent in macrophages, microglia and reactive astrocytes. To determine potential effects of elevated K6 on the regeneration environment, the ability of neurons to adhere to and extend processes on substrata which had been exposed to recombinant K6 was examined. Limited (1 h) or excess (24 h) K6-mediated proteolytic digestion of a growth-facilitatory substrate, laminin, significantly decreased neurite outgrowth. By contrast, similar hydrolysis of a growth-inhibitory substrate, aggrecan, significantly increased neurite extension and cell adherence. These data support the hypothesis that K6 enzymatic cascades mediate events secondary to spinal cord trauma, including dynamic modification of the capacity for axon outgrowth.

Identification and total synthesis of novel fatty acids from the Siphonarid limpet Siphonaria denticulata

The novel fatty acids 17-methyl-6(Z)-octadecenoic acid and 17-methyl-7(Z)-octadecenoic acid were identified for the first time in nature in the mollusk Siphonaria denticulata from Queensland, Australia. The principal fatty acids in the limpet were hexadecanoic acid, octadecanoic acid, and (Z)-9-octadecenoic acid, while the most interesting series of monounsaturated fatty acids was a family of five nonadecenoic acids with double bonds at either Delta(7), Delta(9), Delta(11), Delta(12), or Delta(13). The novel compounds were characterized using a combination of GC-MS and chemical transformations, such as dimethyl disulfide derivatization. The first total syntheses for the two novel methyl-branched nonadecenoic acids are also described, and these were accomplished in four to five steps and in high yields.

Zinc-induced changes in ionic currents of clonal rat pancreatic -cells: activation of ATP-sensitive K+ channels

The effects of zinc (Zn2+) on excitability and ionic conductances were analysed on RINm5F insulinoma cells under whole-cell and outside-out patch-clamp recording conditions. We found that extracellular application of 10-20 microM Zn2+ induced a reversible abolition of Ca2+ action potential firing, which was accompanied by an hyperpolarisation of the resting membrane potential. Higher concentrations of Zn2+, in the tens to hundreds micromolar range, induced a reversible reduction of voltage-gated Ca2+ and, to a lesser extent, K+ currents. Low-voltage-activated Ca2+ currents were more sensitive to Zn2+ block than high voltage-activated Ca2+ currents. The Zn2+-induced hyperpolarisation arose from a dose-dependent increase in a voltage-independent K+ conductance that was pharmacologically identified as an ATP-sensitive K+ (KATP) conductance. The effect was rapid in onset, readily reversible, voltage independent, and related to intracellular ATP concentration. In the presence of 1 mM intracellular ATP, half-maximal activation of KATP channels was obtained with extracellular application of 1.7 microM Zn2+. Single channel analysis revealed that extracellular Zn2+ increased the KATP channel open-state probability with no change in the single channel conductance. Our data support the hypothesis that Zn2+ binding to KATP protein subunits results in an activation of the channels, therefore regulating the resting membrane potential and decreasing the excitability of RINm5F cells. Taken together, our results suggest that Zn2+ can influence insulin secretion in pancreatic beta-cells through a negative feedback loop, involving both KATP and voltage-gated conductances.

Developing a managed care delivery system in New York State for Medicaid recipients with HIV

In the state of New York, models of care known as HIV Special Needs Plans (HIV SNPs) are being developed to meet the unique health and medical needs of Medicaid recipients with HIV. Establishing managed care plans for the 80,000 to 100,000 HIV-infected Medicaid recipients residing in the state has required considerable effort, including distributing planning grants to solicit information and recommendations regarding program and fiscal policy; convening a workgroup to facilitate discussions between the state and the provider and consumer communities; conducting a longitudinal survey to assess the impact of managed care on persons with HIV; and developing a longitudinal, person-based, encounter-level database representing the clinical and service utilization histories of more than 100,000 patients for state fiscal years 1990 to 1996. The key fiscal issues identified and discussed were capitation rates, initial capitalization levels, and risk-adjustment mechanisms. Other pertinent issues included the importance of a benefits package supporting a comprehensive, integrated continuum of state-of-the-art services; marketing and enrollment; attention to provider and consumer training and education needs; and interdependence of financial reimbursement and benefits packages. From our experience in New York State, we conclude that a successful model of Medicaid managed care for persons with HIV should build on the existing infrastructure of services, using a collaborative process among government agencies, healthcare providers, and HIV/AIDS consumer communities. A future challenge lies in the implementation of the HIV SNP model and evaluation of its soundness and ability to ensure quality healthcare services.

An integrated strategy for the process development of a recombinant antibody-cytokine fusion protein expressed in BHK cells

Recombinant fusion proteins offer important new therapeutic approaches for the future. This report describes the use of three different genetic strategies (i.e. "mono-", "bi-" and "tri-cistronic" vectors) to achieve stable secretion from BHK cells of a glycosylated antibody-cytokine fusion protein designed for use in antitumour therapy. It describes selection of a robust and effective production cell line based on stability of secretion of the product, quality of mRNA and protein products and performance in in vitro bioassays for potency. The data obtained at this stage were utilised in the selection of a suitable candidate production cell line. The relative productivity and general performance of the cells in stirred tank and fixed bed culture systems indicated that a variety of cell culture technologies provided robust tools for production of a highly selected cell clone. Consistency of the product glycosylation was determined by analysis of released oligosaccharides using matrix-assisted laser desorption ionisation-time of flight mass spectrometry and high-performance anion exchange chromatography. These investigations showed consistent expression of three glycoforms of the fusion protein which varied in their relative proportions in different culture systems and at different time points in a fixed bed reactor with continuous perfusion. In conclusion, this study dealt with a range of important scientific and technical issues which are essential for regulatory approval and commercial success of a recombinant protein and elucidates some useful markers for process development for similar recombinant biologicals.

[Cardiac rupture in acute myocardial infarct. Presentation of 20 postmortem cases]

With the advancement of the Coronary Care Units in the past three decades, there had been an important reduction in mortality secondary to arrhythmias in acute myocardial infarction (AMI): been now days, cardiogenic shock and cardiac rupture the first and second causes of in-hospital death in these patients. The purpose of this report is to know the anatomoclinical characteristics in our hospital of cardiac rupture and to look for risk factors that may be considered to diagnose at the precise time this complication that might cause sudden death secondary to hemodynamic and electromechanical changes. From 300 postmortem cases with AMI proved clinical, and by anatomopathological studies, 20 cases with cardiac rupture were obtained, among which: 11 (55%) were males with an average age of 61.7 years and 9 (45%) females, with an average age of 60 years. The following coronary risk factors were detected: systemic hypertension in 15 (75%) cases; cigarette smoking in 13 (65%) cases and diabetes mellitus in 11 (55%) cases. Long lasting or recurrent history of chest pain previous to death was present in 14 (70%) cases. Conduction disturbances were detected in 13 (65%) cases; among them, 7 (35%) had third degree heart block in whom permanent pacemaker was inserted; 4 (20%) had CRBBB and 2 (10%) ASB. The average heart weight was 478 gr. in males and 434 gr. in females. Evidence of an old MI was present in 7 (35%) cases. All patients had transmural MI. Free cardiac wall rupture was seen in 14 (70%) cases and from the ventricular septum, 6 (30%) cases. Hemopericardium was present in all cases (100%) with an average amount of 425 ml of blood. Pericarditis in 3 (15%). The average time of evolution since the beginning of the AMI until death were 4 days and the main causes of death were cardiogenic shock in 17 (85%) and congestive heart failure in 3 (15%).

Early hospital discharge of preterm very low birth weight infants

OBJECTIVE

The objective of this study was to investigate whether early discharge from the hospital was feasible for selected very low birth weight (VLBW) infants.

STUDY DESIGN

A randomized clinical trial of discharge of VLBW infants from the neonatal intensive care unit at 1300 gm versus 1800 gm was done comparing weight gain and incidence of infection. Forty-three VLBW infants treated in the neonatal intensive care unit and follow-up clinics of the Hospital Universitario del Valle, Cali, Colombia, were entered into the study at 1300 to 1350 gm when they met behavioral criteria for discharge and the family home was approved.

RESULTS

There were no differences in weight gain or incidence of infection in the home group compared with the hospital group. A significant saving in hospital days and hospital costs was realized for the home group. Family cooperation was heightened in the home group.

CONCLUSIONS

Early discharge from the hospital at weights as low as 1300 to 1350 gm is safe for the VLBW infant when properly selected on the basis of behavioral criteria and environmental approval. The potential savings in hospital costs should be considered when resources are allocated for continued support for these infants.

Timing of surgery after acute myocardial infarction

OBJECTIVE

We wished to determine if timing of surgery, when other co-morbid variables are controlled, influenced outcome after operations for acute myocardial infarction.

DESIGN

Between 3/20/1990 and 6/17/1994, data was prospectively collected on 338 patients undergoing operation for either evolving infarcts (n=73) or up to 21 days after infarction (mean 7.9 days).

SETTING

Tertiary hospital referral center.

PATIENTS

Infarction was diagnosed by CK enzymes or EKG Q-waves preoperatively in 338 patients undergoing surgery. The mean age of the patients was 66.1 years (SD+/-10.5 years), 76 had emergency operations immediately after catheterization (50 following PTCA complications), 223 had urgent operations, and 39 were elective.

INTERVENTIONS

Seventy-three had preoperative ballon pumps, and 259 had one or more mammary artery bypasses with a mean of 3.27 (SD+/-1.0) distal anastomoses.

RESULTS

In-hospital and 30-day survival rate was 95.6% (323/338). Of the 73 variables evaluated by step-wise logistic regression analysis, the multivariate independent preoperative predictors of death were: aortic valve regurgitation, chronic pulmonary disease, preoperative diuretic administration, preoperative balloon pump, preoperative inotropes, and the need for additional concomitant noncardiac surgery. Including the operative variables, the predictors were: preoperative balloon pump, preoperative inotropes, the presence of left main stenosis, preoperative renal failure, chronic pulmonary disease, valve disease, ischemic arrhythmia, pump perfusion time, valve surgery, and homologous blood transfusion volume required. When the postoperative variables were included, the predictors were: preoperative inotropes, postoperative balloon pump, postoperative epinephrine, postoperative permanent stroke, and postoperative acute renal failure. The time between infarction and operation was not an independent prediction (p>0.4) in any of the logistic regression models.

CONCLUSION

Early operation after acute infarction is not in itself a risk factor, rather comorbid disease and preoperative hemodynamic status determine outcome after surgery.

Silent giant left atrium. A case report

A sixty-two-year-old white woman with a 14.5 cm (145 mm) silent giant left atrial enlargement secondary probably to rheumatic heart disease is presented. Aside from mild progressive shortness of breath during the past year, the patient had been asymptomatic all her life. Her clinical picture was manifested for the first time by syncope secondary to slow atrial fibrillation, for which a permanent pacemaker was required. The correct diagnosis of the enlarged chamber was not possible through the routine chest roentgenogram. In this case, the echocardiogram, nuclear angiogram, and computed tomography were the pertinent studies needed to reach the diagnosis.