Greater rate of decline in maximal aerobic capacity with age in physically active vs. sedentary healthy women

Using a meta-analytic approach, we recently reported that the rate of decline in maximal oxygen uptake (VO2 max) with age in healthy women is greatest in the most physically active and smallest in the least active when expressed in milliliters per kilogram per minute per decade. We tested this hypothesis prospectively under well-controlled laboratory conditions by studying 156 healthy, nonobese women (age 20-75 yr): 84 endurance-trained runners (ET) and 72 sedentary subjects (S). ET were matched across the age range for age-adjusted 10-km running performance. Body mass was positively related with age in S but not in ET. Fat-free mass was not different with age in ET or S. Maximal respiratory exchange ratio and rating of perceived exertion were similar across age in ET and S, suggesting equivalent voluntary maximal efforts. There was a significant but modest decline in running mileage, frequency, and speed with advancing age in ET. VO2 max (ml . kg-1 . min-1) was inversely related to age (P < 0.001) in ET (r = -0.82) and S (r = -0.71) and was higher at any age in ET. Consistent with our meta-analysic findings, the absolute rate of decline in VO2 max was greater in ET (-5.7 ml . kg-1 . min-1 . decade-1) compared with S (-3.2 ml . kg-1 . min-1 . decade-1; P < 0. 01), but the relative (%) rate of decline was similar (-9.7 vs -9. 1%/decade; not significant). The greater absolute rate of decline in VO2 max in ET compared with S was not associated with a greater rate of decline in maximal heart rate (-5.6 vs. -6.2 beats . min-1 . decade-1), nor was it related to training factors. The present cross-sectional findings provide additional evidence that the absolute, but not the relative, rate of decline in maximal aerobic capacity with age may be greater in highly physically active women compared with their sedentary healthy peers. This difference does not appear to be related to age-associated changes in maximal heart rate, body composition, or training factors.     

Should laparoscopic appendectomy be avoided for complicated appendicitis in children?

BACKGROUND/PURPOSE: Laparoscopic appendectomy is becoming the preferred technique for treating acute appendicitis. However, recent literature on adults suggests that laparoscopic appendectomy may increase the risk for postoperative infectious complications in complicated (gangrenous or perforated) cases. This study was undertaken to compare the results of open versus laparoscopic appendectomy for complicated appendicitis in children. METHODS: A retrospective review from two institutions was performed for all children treated operatively for complicated appendicitis from January 1994 through November 1996. RESULTS: Fifty-six cases were identified. Twenty-seven children underwent laparoscopic appendectomy, whereas 22 underwent open appendectomy. Seven children underwent conversion from laparoscopic to open surgery. Operating times and length of hospital stay did not differ significantly between the laparoscopic and open groups. Postoperative complications developed in 24 children (42.8%). Complications were more frequent after laparoscopic appendectomy compared with open appendectomy (56% v 18%, P = .002). A postoperative intraabdominal abscess (IAA) developed in 14 children (25%). An IAA occurred in two children after open appendectomy compared with 11 children after laparoscopic appendectomy (9% v 41%, P = .01). CONCLUSION: The findings suggest that laparoscopic appendectomy should be avoided in children who have complicated appendicitis because of the increased risk for postoperative intraabdominal abscesses. The authors propose a prospective, randomized trial to verify this finding.     

Application of pbp1A PCR in identification of penicillin-resistant Streptococcus pneumoniae

A seminested PCR assay, based on the amplification of the pneumococcal pbp1A gene, was developed for the detection of penicillin resistance in clinical isolates of Streptococcus pneumoniae. The assay was able to differentiate between intermediate (MICs = 0.25 to 0.5 microgram/ml) and higher-level (MICs = >/=1 microgram/ml) resistance. Two species-specific primers, 1A-1 and 1A-2, which amplified a 1,043-bp region of the pbp1A penicillin-binding region, were used for pneumococcal detection. Two resistance primers, 1A-R1 and 1A-R2, were designed to bind to altered areas of the pbp1A gene which, together with the downstream primer 1A-2, amplify DNA from isolates with penicillin MICs of >/=0.25 and >/=1 microgram/ml, respectively. A total of 183 clinical isolates were tested with the pbp1A assay. For 98.3% (180 of 183) of these isolates, the PCR results obtained were in agreement with the MIC data. The positive and negative predictive values of the assay were 100 and 91%, respectively, for detecting strains for which the MICs were >/=0.25 microgram/ml and were both 100% for strains for which the MICs were >/=1 microgram/ml.     

The tmRNA website

Stool specimens of 104 primary schoolchildren (mean+/-SD age = 8.2+/-0.3 years) were examined for helminth eggs and for occult blood to investigate the possibility that trichuriasis causes occult intestinal bleeding in the absence of the overt Trichuris dysentery syndrome. A commercially available guaiac test was used to detect fecal occult blood. Sixty-one children had Trichuris infection, 11 of whom had heavy infections (> 10,000 eggs per gram of feces [epg]), and 53 had Ascaris infections. No hookworm infection was detected. Baseline screening yielded only one weakly positive occult blood test result in a child with a light (800 epg) Trichuris infection. Serial stool occult blood testing on the 11 subjects with heavy trichuriasis and 8 uninfected controls yielded a single weakly positive result in the control group. The results provide no evidence that trichuriasis predisposes to significant occult gastrointestinal bleeding in children in the absence of the dysenteric syndrome.     

Application of genetic markers to the identification of recrudescent Plasmodium falciparum infections on the northwestern border of Thailand

PATIENTS AND METHODS: The role of cerebral magnetic resonance imaging (MRI) in the diagnosis of growth hormone (GH) deficiency in children has been studied in 100 children. The diagnosis of GH deficiency was assessed at a mean age of 6.7 +/- 4.1 years: morphological abnormalities of the hypothalamic-pituitary (HP) region have been studied in three different groups: in the first group (70 cases), the neurohypophysis was present and normally located; in the second group (ten cases) it was missing; in the third group (20 cases) the neurohypophysis was ectopic (truncated stalk syndrome with ectopic neurohypophysis, small antehypophysis, thin or non-visualized stalk). RESULTS: In the majority of cases, children presenting with only one morphological abnormality of the HP region (ectopic neurohypophysis or small antehypophysis or non-visualized or thin stalk) had an isolated GH deficiency. When multiple morphological abnormalities were present, anterior pituitary deficiency was multiple in more than half the cases. Cerebral midline anomalies (above all Chiari I malformation and basipharyngeal canal) had been observed in 20% of the children presenting with GH deficiency. In the majority of cases (95%), these anomalies were associated with one or more abnormalities of the HP region. A familial case is reported: morphological anomalies of the HP region were different for both siblings. Genetic factors are evoked. CONCLUSION: The severity of the hormone deficiency is correlated to the ectopic location of the neurohypophysis, the thin appearance or non visibility of the pituitary stalk and the associated midline anomalies.     

A porous silicon-based optical interferometric biosensor

A biosensor has been developed based on induced wavelength shifts in the Fabry-Perot fringes in the visible-light reflection spectrum of appropriately derivatized thin films of porous silicon semiconductors. Binding of molecules induced changes in the refractive index of the porous silicon. The validity and sensitivity of the system are demonstrated for small organic molecules (biotin and digoxigenin), 16-nucleotide DNA oligomers, and proteins (streptavidin and antibodies) at pico- and femtomolar analyte concentrations. The sensor is also highly effective for detecting single and multilayered molecular assemblies.     

Injury control in practice. Home radiator burns in inner-city children

OBJECTIVE: To describe thermal burns from radiators in the homes of children in the inner city and an intervention to decrease the risk for this pediatric injury. SETTING: Academic medical center in Chicago. PATIENTS: Case series of 10 radiator-related burns. RESULTS: The burns described were found to be clustered in an area of a public housing project served by steam radiators. No burns were associated with hot water radiators. Just 14% of housing units with young children had adequate radiator covers and radiator pipe insulation. Radiator covers and insulation have now been replaced or repaired in all units of the 11 housing project buildings served by steam radiators. CONCLUSIONS: Steam radiators in the home represent a particular childhood burn hazard. Community-based clinicians are in a unique position to recognize local patterns of injury and work with other agencies in injury control efforts.     

Dietary conjugated linoleic acid normalizes impaired glucose tolerance in the Zucker diabetic fatty fa/fa rat

Conjugated linoleic acid (CLA) is a naturally occurring fatty acid which has anti-carcinogenic and anti-atherogenic properties. CLA activates PPAR alpha in liver, and shares functional similarities to ligands of PPAR gamma, the thiazolidinediones, which are potent insulin sensitizers. We provide the first evidence that CLA is able to normalize impaired glucose tolerance and improve hyperinsulinemia in the pre-diabetic ZDF rat. Additionally, dietary CLA increased steady state levels of aP2 mRNA in adipose tissue of fatty ZDF rats compared to controls, consistent with activation of PPAR gamma. The insulin sensitizing effects of CLA are due, at least in part, to activation of PPAR gamma since increasing levels of CLA induced a dose-dependent transactivation of PPAR gamma in CV-1 cells cotransfected with PPAR gamma and PPRE X 3-luciferase reporter construct. CLA effects on glucose tolerance and glucose homeostasis indicate that dietary CLA may prove to be an important therapy for the prevention and treatment of NIDDM.     

The number of glutamate transporter subtype molecules at glutamatergic synapses: chemical and stereological quantification in young adult rat brain

The role of transporters in shaping the glutamate concentration in the extracellular space after synaptic release is controversial because of their slow cycling and because diffusion alone gives a rapid removal. The transporter densities have been measured electrophysiologically, but these data are from immature brains and do not give precise information on the concentrations of the individual transporter subtypes. Here we show by quantitative immunoblotting that the numbers of the astroglial glutamate transporters GLAST (EAAT1) and GLT (EAAT2) are 3200 and 12,000 per micrometer3 tissue in the stratum radiatum of adult rat hippocampus (CA1) and 18,000 and 2800 in the cerebellar molecular layer, respectively. The total astroglial cell surface is 1.4 and 3.8 m2/cm3 in the two regions, respectively, implying average densities of GLAST and GLT molecules in the membranes around 2300 and 8500 micrometer-2 in the former and 4700 and 740 micrometer-2 in the latter region. The total concentration of glial glutamate transporters in both regions corresponds to three to five times the estimated number of glutamate molecules in one synaptic vesicle from each of all glutamatergic synapses. However, the role of glial glutamate transporters in limiting synaptic spillover is likely to vary between the two regions because of differences in the distribution of astroglia. Synapses are completely ensheathed and separated from each other by astroglia in the cerebellar molecular layer. In contrast, synapses in hippocampus (stratum radiatum) are only contacted by astroglia and are often found side by side without intervening glial processes.     

Lentil lectin enriched microsomes from the plasma membrane of the human B-lymphocyte cell line H2LCL carry a heavy load of type-1 porin

Using an established biochemical approach, five subcellular fractions of human B lymphocytes were prepared by differential centrifugation. Crude membranes were passed over a lentil lectin column to enrich carbohydrate-coated cell surface microsomes. The lectin-bound fraction contained a high amount of plasma membrane-derived microsomes as indicated by cell surface markers. All subcellular fractions in Western blots proved to contain distinct but variable amounts of porin. There was a strong increase in porin content from crude membranes to plasma membrane-derived vesicles. The porin content of this fraction appeared to be higher than that of mitochondria. In the final step the plasma membrane-derived microsome fraction proved to be devoid of contamination by outer mitochondrial membranes, as revealed by antibodies against the established markers MAO B and Tom20 applied in Western blots. These data prove the extramitochondrial expression of human type-1 porin/ type-1 VDAC.