[Relationship Between General Cognitive Abilities and School Achievement: The Mediation Role of Learning Behavior]. / Zum Zusammenhang von allgemeinen kognitiven Fähigkeiten und schulischer Leistung: Welche Rolle spielt das Lernverhalten?

BACKGROUND: General cognitive abilities are still considered as the most important predictor of school achievement and success. Whether the high correlation (r=0.50) can be explained by other variables has not yet been studied. Learning behavior can be discussed as one factor that influences the relationship between general cognitive abilities and school achievement. METHODS: This study examined the relationship between intelligence, school achievement and learning behavior. Mediator analyses were conducted to check whether learning behavior would mediate the relationship between general cognitive abilities and school grades in mathematics and German. RESULTS: Statistical analyses confirmed that the relationship between general cognitive abilities and school achievement was fully mediated by learning behavior for German, whereas intelligence seemed to be the only predictor for achievement in mathematics. These results could be confirmed by non-parametric bootstrapping procedures. CONCLUSION: RESULTS indicate that special training of learning behavior may have a positive impact on school success, even for children and adolescents with low IQ.

Nanoparticle technology: addressing the fundamental roadblocks to protein biomarker discovery.

Clinically relevant biomarkers exist in blood and body fluids in extremely low concentrations, are masked by high abundance high molecular weight proteins, and often undergo degradation during collection and transport due to endogenous and exogenous proteinases. Nanoparticles composed of a N-isopropylacrylamide hydrogel core shell functionalized with internal affinity baits are a new technology that can address all of these critical analytical challenges for disease biomarker discovery and measurement. Core-shell, bait containing, nanoparticles can perform four functions in one step, in solution, in complex biologic fluids (e.g. blood or urine): a) molecular size sieving, b) complete exclusion of high abundance unwanted proteins, c) target analyte affinity sequestration, and d) complete protection of captured analytes from degradation. Targeted classes of protein analytes sequestered by the particles can be concentrated in small volumes to effectively amplify (up to 100 fold or greater depending on the starting sample volume) the sensitivity of mass spectrometry, western blotting, and immunoassays. The materials utilized for the manufacture of the particles are economical, stable overtime, and remain fully soluble in body fluids to achieve virtually 100 percent capture of all solution phase target proteins within a few minutes.

Ketoconazole inhibits organic osmolyte efflux and induces heat shock proteins in rat renal medulla.

Although ketoconazole (KC) is known to inhibit the cellular efflux of organic osmolytes in vitro, it is not known whether this effect can also be shown in vivo. Inhibition of osmolyte efflux by KC would impair osmotic adaptation and result in stress to the cells of the renal medulla when extracellular osmolality falls. Stress-inducible heat shock proteins (HSPs) may also participate in this response to osmotic stress. The aim of the present study was thus to establish whether KC inhibits organic osmolyte efflux from the cells of the renal medulla in vivo in response to a furosemide diuresis, and to establish whether HSPs are involved. A 20-minute furosemide infusion reduced urine osmolality and medullary urea content in control and KC-treated rats similarly. However, the efflux of methylamines (glycerophosphorylcholine, betaine) and polyols (myo-inositol, sorbitol) was attenuated in KC-treated rats while the efflux of amino acids was not significantly affected. Phosphorylation of HSP25 after the 20-minute furosemide diuresis was increased in KC rats. With continuing diuresis this returned to control levels after three hours. While short-term (up to 3 hr) diuresis did not alter the absolute amounts of HSPs in the renal medulla, long-term (24 or 48 hr) diuresis was associated with significantly increased amounts of HSP25 and HSP72 in KC-treated rats compared with control. These results suggest that KC inhibits the efflux of methylamines and polyols, thus impeding osmoadaptation of renal medullary cells during the onset of diuresis. This situation apparently increases the osmotic stress experienced by the cells of the renal medulla and provokes expression of HSP25 and HSP72.

Heat shock proteins HSP25, HSP60, HSP72, HSP73 in isoosmotic cortex and hyperosmotic medulla of rat kidney.

The distribution of heat shock proteins (HSP) HSP60, HSP73, HSP72 and HSP25 in the isoosmotic cortex and the hyperosmotic medulla of the rat kidney was investigated using Western blot analysis and immunohistochemistry. HSP73 was homogeneously distributed throughout the whole kidney. The level of HSP60 was high in the renal cortex and low in the medulla. HSP25 and HSP72 were present in large amounts in the medulla. Only low levels of HSP25 and almost undetectable amounts of HSP72 were found in the cortex. HSP25 exists in one nonphosphorylated and several phosphorylated isoforms. Western blot analysis preceded by isoelectric focussing showed that HSP25 predominates in its nonphosphorylated form in the outer medulla but in its phosphorylated form in cortex and inner medulla. Although this intrarenal distribution pattern was not changed during prolonged anaesthesia (thiobutabarbital sodium), a shift from the nonphosphorylated to the phosphorylated isoforms of HSP25 occurred in the medulla. The characteristic intrarenal distribution of the constitutively expressed HSPs (HSP73, HSP60, HSP25) may reflect different states of metabolic activity in the isoosmotic (cortex) and hyperosmotic (medulla) zones of the kidney. The high content of inducible HSP72 in the medulla most likely is a consequence of the osmotic stress imposed upon the cells by the high urea and salt concentrations in the hyperosmotic medullary environment.

Functional status of persons with HIV infection in an ambulatory setting.

The objective of this project was to study the functional status of HIV-infected persons seen in an ambulatory care setting. We reviewed baseline clinical and demographic data on patients with HIV infection presenting for care between December 1988 and May 1991 at the HIV Clinic of the Johns Hopkins Hospital, an urban, primary care institution. Functional status was assessed at baseline in a comprehensive psychosocial assessment. Patients were asked to report on their ability to perform six activities of daily living (ADL) and nine instrumental activities of daily living (IADL). The main outcome measures were dependency in one or more ADL and death as ascertained by review of clinic death records and Maryland State Death Registries. All 728 patients had assessments of functional status. Of these, 18% reported dependencies in one or more activity, with most of these (14%) reporting dependencies in IADLs only. Dependencies were more common in persons with an AIDS diagnosis (32% vs. 15%, p < 0.001). The majority of the dependencies reported by AIDS patients were also in IADLs. Mean CD4 counts were lower for persons reporting dependencies than for those who reported no dependencies (p = 0.02). No independent associations were found between functional limitation and demographic variables. The risk of death was greater in patients with dependencies than in patients with no dependencies, even when adjusting for CD4 count and AIDS diagnosis (O.R. = 2.32, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Perioperative care of patients undergoing spinal stabilization with internal fixation (continuing education credit).

1. Low back pain affects approximately 80% of the adult population. There are between 200,000 and 500,000 spinal surgeries performed every year. 2. New spinal implant systems offer hope for persons with failed spinal surgery--as well as for those with spinal fractures, metastatic disease, and severe degenerative disorders. 3. Although complications can develop, the benefits of new spinal fixation systems far outweigh the problems.

[Somatostatin receptor scintigraphy in the primary diagnosis and follow-up care of gastrinoma]. / Somatostatinrezeptor-Szintigraphie in der Primärdiagnostik und Nachsorge bei Gastrinomen.

Somatostatin receptor scintigraphy (SRS) was performed in 14 patients (five men, nine women; mean age 51.5 [20-71] years) with Zollinger-Ellison syndrome (ZES), a gastrinoma proven in 7 and suspected on clinical or biochemical grounds in 7. The results were compared with those obtained by other methods (ultrasound, computed tomography, angiography). All 12 known tumour manifestations were demonstrated by SRS in seven patients with histologically confirmed gastrinoma. In four patients previously non-localized tumour was revealed by SRS, while in seven other patients the procedure led to modification of the treatment (primary tumour resection: n = 3, resection of metastases: n = 2, percutaneous radiation or chemoembolization: one each). These results suggest the following indications for SRS: (1) staging or re-staging in histologically proven gastrinoma and (2) search for primary tumour in clinically and biochemically suspected ZES.

Impact of the 1993 revision of the AIDS case definition on the prevalence of AIDS in a clinical setting.

OBJECTIVE: To determine the impact of the 1993 revision of the Centers for Disease Control and Prevention (CDC) AIDS surveillance case definition on the prevalence of AIDS. DESIGN: Review of prospectively collected baseline clinical and demographic data on HIV-infected patients presenting for care between December 1988 and May 1991. SETTING: The HIV Clinic of the Johns Hopkins Hospital, an urban, primary care institution. MAIN OUTCOME MEASURE: Diagnosis of AIDS by the 1987 (specific indicator diseases) or the 1993 (indicator diseases, pulmonary tuberculosis, recurrent bacterial pneumonia, cervical carcinoma, or CD4 lymphocyte count < 200 x 10(6)/l) CDC case definition. RESULTS: Of 955 patients evaluated, 122 (13%) had AIDS by the 1987 case definition at presentation. An additional 126 (13%) met the 1993 but not the 1987 case definition. Patients meeting only the 1993 case definition were more likely to be female [28 versus 14%; odds ratio (OR), 2.4; 95% confidence interval (CI), 1.2-3.0; P = 0.01] and intravenous drug users (40 versus 26%; OR, 2.0; 95% CI, 1.1-3.3; P = 0.02) than patients meeting the 1987 case definition. Fifty-five per cent of patients meeting only the 1993 case definition were asymptomatic, and 7% (nine patients) had new indicator diseases but CD4 counts > 200 x 10(6)/l. Median time to progression from a diagnosis of AIDS by the 1993 case definition to diagnosis by the 1987 case definition was 435 days. Patients with AIDS by the 1987 case definition had a median survival of 594 days from presentation (2-year survival, 42%), while median survival time for patients with AIDS by the 1993 case definition only was 947 days (2-year survival, 60%; P < 0.005). CONCLUSIONS: The proposed 1993 revision of the AIDS surveillance case definition would double the number of prevalent AIDS cases, with significant increases in the proportion of cases who are female, intravenous drug users, or asymptomatic. Survival of patients meeting the 1993 case definition is significantly longer than that of patients meeting the 1987 case definition. The new AIDS case definition will have a major impact both on AIDS surveillance and on medical and social service programs that use diagnosis of AIDS as a criterion for eligibility for services.

Comparison of low molecular weight heparin and standard heparin in hemodialysis.

The anticoagulant and antithrombotic effect of heparin has been known for many decades. Since low molecular weight heparin has been available, several advantages over standard heparin were observed, especially in long-term use during hemodialysis. In 27 patients, we found a lower bleeding risk, a lower need for erythrocyte transfusions, a lesser increase in activity of various coagulation factors, and lower triglyceride levels. Therefore, low molecular weight heparin would appear to be a good alternative to standard heparin in dialysis patients.

Splash basin contamination in orthopaedic surgery.

Samples of splash basin fluid were cultured at the end of 78 randomly selected orthopedic operations. Fifty-eight (74%) of the specimens were positive on culture. Staphylococcus epidermidis was the prevalent organism. Thirty-four (59%) of the positive cultures grew multiple organisms. Seven (12%) grew more than 100 colonies per 100 ml specimen. This study demonstrates that splash basin fluid is frequently contaminated and may be a source of wound contamination during orthopedic surgery. Implants should not be placed in the splash basin, and instruments placed in it should not be returned to the operative wound.

Human platelet basic protein associated with antiheparin and mitogenic activities: purification and partial characterization.

Platelet basic protein (PBP) (isoelectric point, 10.0-10.5; apparent Mr, 11,000-15,000) has been purified to homogeneity from material secreted by fresh human platelets after stimulation by thrombin. The purification, using preparative isoelectric focusing and chromatography on heparin-Sepharose, yielded two additional peptides with antiheparin activity that were immunologically identical with PBP: low-affinity platelet factor 4 and beta-thromboglubulin. The purity of the peptides was confirmed by immuoelectrophoresis and by NH2-terminal amino acid analysis. Dansyl chloride-treated PBP yielded a single dansylated amino acid residue (glycine). By using a specific radioimmunoassay it was shown that 10(9) human platelets contain 2-3 microgram of PBP which can be released in response to specific stimulation. PBP is associated with mitogenic activity as assayed in Swiss 3T3 mouse cells cultured in low-serum (0.4-1.5%) medium at levels of about 1 ng/ml and saturating at 10-40 ng/ml. The biological activity of different PBP preparations was variable, presumably due to inhibition by the varying amounts of ampholytes that interfered with the mitogenic activity of the peptide. Mitogenic activity was eluted from NaDodSO4/polyacrylamide gels and shown to comigrate with immunoreactive material and with conventional marker proteins of 14,000-17,000 daltons or with histones of 11,000-15,000 daltons. Evidence is presented that PBP is different from cationic platelet-derived growth factor which has an apparent Mr of 30,000.

The CSF pressure-volume relationship before and after cardiac arrest in the cat.

The CSF pressure-volume (P-V) function was evaluated before and after cardiac arrest in 15 cats. The CSF volume change was produced by bolus loading (loading rate, greater than 0.1 mL/s) of the CSF space. Comparison of the CSF P-V function before and after cardiac arrest was made over a CSF pressure range of 5 to 46 mm Hg and for a CSF volume change of up to 9% of total CSF volume. After cardiac arrest, all CSF P-V curves were well described by the mathematical model konwn to be valid under normal physiological conditions. In eight animals, there was no significant difference between the prearrest and postarrest P-V functions. For the seven animals demonstrating a significant difference between prearrest and postarrest P-V data, all but one of the postarrest P-V curves were within the normal range. These results suggest that the shape of the CSF P-V curve is not substantially altered by cardiac arrest. We conclude that under normal circumstances material properties of brain tissue are the most important factors in determining the configuration of the CSF P-V curve and that under normal circumstances cerebral hemodynamic factors do not affect the shape of this curve.

Bolous versus steady-state infusion for determination of CSF outflow resistance.

For rapid changes in cerebrospinal fluid volume an exponential relationship was demonstrated between CSF pressure and CSF volume in 15 cats. This relationship was valid over a CSF pressure range from 7 to 50 mm Hg and for acute increases of up to 9% to total CSF volume (approximately 13 ml for humans). Our data agree well with previous reports for the cat. A similar relationship has been shown in the dog and in humans. It has been claimed that, given the equations for CSF bulk flow and the exponential relationship between CSF pressure and CSF volume, one can calculate CSF outflow resistance by observing the decay of CSF pressure after a bolus injection into the CSF space. This claim was evaluated in an additional 18 cats. In these animals CSF outflow resistance calculated by the bolus method was compared with resistance calculated by a steady-state infusion method over the CSF outflow resistance range of 74 to 293 mm Hg/ml min-1. Resistance calculated by the bolus method underestimated resistance calculated by the steady-state method, and this underestimate grew larger with increasing resistance. The bolus technique is therefore not a valid method for determining CSF outflow resistance. The explanation offered for these results is that the decay of CSF pressure after a bolus injection into the CSF space occurs not only because of runoff of the injected volume of CSF but also because of "pressure relaxation" of the brain parenchyma around the CSF space. The phenomenon of pressure relaxation was not considered in developing the equation for calculation of CSF outflow resistance by the bolus technique. The time dependency of pressure relaxation allows for a fundamental element of hysteresis within the CSF space. A method of quantifying this element of hysteresis is suggested.