POROSITY: III. WATER AS AN ABSORPTION LIQUID

Classes of absorption method .—The ordinary immersion method has been shown by previous investigators to be unreliable. Simple immersion in low vacuo without boiling is also shown theoretically to be unreliable. An analysis of the results of previous investigators indicates the presence of unsuspected sources of error. Effect of adsorbed gases upon dry weights of test pieces .—Dry air is shown to be without appreciable influence. Depending upon the humidity of the atmosphere, adsorbed water vapor may cause errors up to 2 per cent in the porosity value. Perfectly dry fired clay will remove water from conc. H₂SO₄, and from fused CaCl₂. Saturation by boiling at atmospheric pressure .—A one hour's (and in one instance a 5 hours') boiling failed to saturate completely. On continued boiling the saturated weight increases linearly with the time and this in spite of the fact that appreciable quantities of dissolved materials are removed from the test piece by the hot water. This result is shown to be due to a gradual and continuous rehydration of the clay by the hot water. The error from this factor may amount to as much as 3% and the error from dissolved materials to as much as 2%, during a 3 hours' boiling. The nature of the dissolved material was determined. Method of cooling the test piece .—It is recommended that the test piece be kept in a closed vessel over 95% sulphuric acid for several hours before its dry weight is taken. Saturation procedure .—A vacuum method is described in which water may be employed as the saturation liquid under conditions where the above sources of error are reduced to a minimum. The method is not however recommended as a primary standard. Necessity of a soaking period .—It is shown from theoretical considerations that a soaking period is necessary and methods are given for calculating and for measuring the minimum soaking period required for a given test piece and a given liquid of known penetrativity.     

Changes in serum osteocalcin, plasma phylloquinone, and urinary gamma-carboxyglutamic acid in response to altered intakes of dietary phylloquinone in human subjects

The response of osteocalcin and other biochemical markers of vitamin K status to diets formulated to contain different amounts of phylloquinone was assessed in nine healthy subjects aged 20-33 y. Subjects resided in a metabolic ward for two 15-d cycles with a minimum of 6 wk between cycles. A mixed diet containing 100 micrograms phylloquinone/d was fed throughout both cycles; however, the phylloquinone content of one of the cycles was increased to a total of 420 micrograms/d on days 6 through 10 by fortifying corn oil in the diet with phylloquinone (supplemented diet). Total serum osteocalcin concentrations were not affected by either of the dietary treatments. The percentage of undercarboxylated osteocalcin increased an average of 28% over the 15-d cycle with the mixed diet (P < 0.05) and declined significantly an average of 41% with 5 d of the supplemented diet (day 6: 21.9 +/- 1.3%, day 11: 12.8 +/- 1.1%; P = 0.0001) with a rise after the return to the mixed diet (16.7 +/- 1.3%, P < 0.001). Plasma phylloquinone concentrations increased significantly with supplementation (day 6: 0.95 +/- 0.16 nmol/L, day 11: 1.40 +/- 0.29 nmol/L; P < 0.001) and then rapidly returned to presupplementation concentrations on returning to the mixed diet. Twenty-four-hour ratios of urinary gamma-carboxyglutamic acid to creatinine were unchanged with the supplemented diet; however, excretion declined to 91 +/- 2% of baseline after 10 d on the mixed diet (P = 0.01). These results show that undercarboxylated osteocalcin, plasma phylloquinone, and urinary gamma-carboxyglutamic acid excretion appear to be sensitive measures of vitamin K nutritional status because all of these variables were responsive to changes in dietary intake.     

Lizards as hosts for immature Ixodes scapularis (Acari: Ixodidae) in North Carolina

Previously archived museum specimens of lizards collected throughout North Carolina were examined for Ixodes scapularis (Say). Lizards (n = 1,349) collected in 80 of North Carolina's 100 counties were examined. Lizards with ticks were collected in 23 (29%) of the 80 counties from which lizards were examined. I. scapularis was detected on 8.7% (n = 117) of the lizards and was the sole species of tick obtained from lizards. Immature ticks were most frequently found on the southeastern five-lined skink, Eumeces inexpectatus, and the eastern glass lizard, Ophisaurus ventralis. Larvae were most frequently found on the six-lined racerunner, Cnemidophorus sexlineatus. One C. sexlineatus harbored 177 larvae and 2 nymphs. Nymphs were most frequently observed on E. inexpectatus. The majority of counties (chi 2, P < 0.01) where ticks were found on lizards were in the Coastal Plain.     

Paraneoplastic limbic encephalitis

BACKGROUND: Polymorphonuclear elastase is an early and sensitive indicator of neonatal infection when performed at the beginning of clinical symptoms. PATIENTS AND METHODS: To investigate the diagnostic value of elastase measurement in cord blood immediately after birth, 211 neonates (103 boys vs 108 girls, 154 vaginal delivery vs 57 cesarean section). Mean gestational age 38.9 weeks (range: 30-42), mean birth weight 3,260 g (range: 1,430-4,920 g). After clinical, bacterial and biological screening, the infants were classified in three groups. Group A (n = 118): none infectious risk factor neither clinical signs of infection; group B (n = 79): one or more risk factors but no evidence of infection; group C (n = 14): proved or probable infection. Polymorphonuclear elastase was measured in cord blood of all infants using an heterogeneous enzyme-linked-immunosorbent assay. RESULTS: We observed higher elastase values in group C (176 +/- 67 micrograms/L) than in group A (91 +/- 64 micrograms/L) and B (67 +/- 61 micrograms/L) (mean +/- SD, P = 0.0001). With a cutoff value fixed at 80 micrograms/L, the sensitivity of this test applicated to neonates presenting materno-fetal infectious risk factor(s) was 85% (12/14), specificity 74% (59/79), positive predictive value 37%, and negative predictive value 96%. CONCLUSION: Because two of the 14 infected infants (15%) were not detected by elastase dosage in cord blood, this test cannot be used as an early indicator of materno-fetal infection.     

Temporal expression of PTHrP during endochondral bone formation in mouse and intramembranous bone formation in an in vivo rabbit model

Expression of parathyroid hormone-related protein (PTHrP) messenger RNA (mRNA) and protein was investigated throughout the developmental progression of endochondral bone formation in mouse and intramembranous bone formation in an in vivo model in rabbit, using in situ hybridization and immunohistochemistry. Endochondral bone formation was investigated in a developing embryo, newborn, and adult mouse. In fetal long bones through to newborn (day 7), PTHrP mRNA and protein were consistently expressed in chondrocytes within the proliferative, transitional, and hypertrophic zones. In addition, high levels of PTHrP were also detected in osteoblasts on the surface of trabecular bone surfaces. Similarly, at the adult stage (week 7), PTHrP mRNA and protein were consistently expressed in chondrocytes at epiphyseal ends of the subarticular cartilage, within cortical periosteum, as well as in osteoblasts located at the metaphyseal trabecular bone surfaces. Using an in vivo intramembranous bone formation model in rabbits, expression of PTHrP mRNA and protein was demonstrated in preosteoblasts prior to trabecular bone formation (1-week bone harvest). As bone formed (2-, 3-, and 4-week bone tissue harvests), PTHrP mRNA and protein were highly expressed in actively synthesizing osteoblasts and in those osteocytes embedded within the superficial layers of the bone matrix. Lining osteoblasts and osteocytes buried deeply in the bone matrix displayed weak or no signal for PTHrP. The pattern of spatial and temporal expression of PTHrP demonstrated in cartilage cells and osteoblasts in the two systems suggests an important role of PTHrP in both endochondral and intramembranous bone formation.     

Intracellular sequestration of sodium by a novel Na+/H+ exchanger in yeast is enhanced by mutations in the plasma membrane H+-ATPase. Insights into mechanisms of sodium tolerance

Sodium tolerance in yeast is disrupted by mutations in calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, which is required for modulation of Na+ uptake and efflux mechanisms. Five Na+-tolerant mutants were isolated by selecting for suppressors of calcineurin mutations, and mapped to the PMA1 gene, encoding the plasma membrane H+-ATPase. One mutant, pma1-alpha4, which has the single amino acid change Glu367 --> Lys at a highly conserved site within the catalytic domain of the ATPase, was analyzed in detail to determine the mechanism of Na+ tolerance. After exposure to Na+ in the culture medium, 22Na influx in the pma1 mutant was reduced 2-fold relative to control, consistent with a similar decrease in ATPase activity. Efflux of 22Na from intact cells was relatively unchanged in the pma1 mutant. However, selective permeabilization of the plasma membrane revealed that mutant cells retained up to 80% of intracellular Na+ within a slowly exchanging pool. We show that NHX1, a novel gene homologous to the mammalian NHE family of Na+/H+ exchangers, is required for Na+ sequestration in yeast and contributes to the Na+-tolerant phenotype of pma1-alpha4.     

The role of vitamin D derivatives and retinoids in the differentiation of human leukaemia cells

The capabilities of 1alpha, 25-dihydroxyvitamin D3 (1,25(OH)2D3), and two novel vitamin D analogues, EB1089 and KH1060, to induce the differentiation of two established leukaemia cell lines, U937 and HL-60, were assessed alone or in combination with the retinoid compounds, 9-cis retinoic acid (9-cis RA) and all-trans retinoic acid (ATRA). The vitamin D derivatives acted to increase the differentiation of U937 and HL-60 cell cultures in a dose-dependent manner, as determined by nitroblue tetrazolium (NBT) reduction, with EB1089 and KH1060 being more effective than the native hormone. As an additional index of leukaemic cell differentiation, induction of expression of the phenotypic cell surface antigen, CD14, and the beta2-integrins, CD11b and CD18 by the vitamin D and retinoid compounds were monitored using fluorescence activated cell sorting (FACS) analyses. Following 96-hr treatment of U937 and HL-60 cells with 5 x 10(-10) M of the vitamin D derivatives, a striking increase in CD14 antigen expression was apparent, indicating the promotion by these compounds of a monocyte/macrophage lineage of cells. CD11b and CD18 antigen expression were also raised above control levels. In contrast, both retinoid compounds used at the higher concentration of 1 x 10(-8) M were not effective inducers of CD14 antigen expression. However, CD11b and CD18 were both readily increased in U937 and HL-60 cell cultures. Treatment of U937 cell cultures with the vitamin D compounds and the retinoids resulted in cooperative effects on induction of differentiation, with correlation by both NBT reduction and FACS analyses of CD14 antigen expression. The presence of 9-cis RA or ATRA appeared to contribute to the further increase of CD14 in these cells. HL-60 cell cotreatment with these compounds also displayed enhanced cooperative effects in phagocytic function by NBT reduction. However, analysis of CD14 revealed a dramatic diminution in HL-60 cells treated with the combinations of the vitamin D derivatives and the retinoids. Assessment of HL-60 cell morphology treated with these combinations demonstrated the presence of a mixed population of monocytes and granulocytes. CD11b and CD18 antigen expression was also enhanced in both cell lines with cotreatment. The ability of EB1089 and KH1060 to induce leukaemic cell differentiation may provide an additional option for therapeutic use alone or together with other differentiation agents such as 9-cis RA or ATRA.     

Group B Streptococcal septicaemia/meningitis in neonates in a Singapore teaching hospital

Several studies have indicated that frequent allelic losses in some specific chromosomal regions occur during colorectal cancer (CRC) progression. To clarify the correlation between such allelic losses and metastatic potential, the allelotype of lymph node-positive early CRCs, which are small but extremely malignant cancers consisting of metastatically competent cells, were investigated. Nineteen paraffin-embedded specimens of early CRC (pT1 tumors according to TNM classification) with positive lymph nodes were collected. The tumor tissues were examined for loss of heterozygosity (LOH), using microsatellite markers on chromosomes 1p34-36, 8p21-22, 14q32, 18q21 and 22q12-13. The relationship between p53 protein expression and the metastatic status was also investigated by immunohistochemical staining. A group of 20 early CRCs with negative lymph nodes having a similar distribution of macroscopic appearance were used as controls. Among the 19 node-positive tumors, LOH at 8p21-22 and 18q21 was detected in 11 cases (57.9%) and 17 cases (89.4%), respectively. Allelic losses within these 2 regions in node-positive tumors were significantly more frequent than that in node-negative ones (p < 0.01). No significant correlation was found between LOH at 1p34-36, 14q32 or 22q12-13 and lymph node metastasis. p53 protein expression was not significantly associated with lymph node metastasis. Our results suggest that putative tumor suppressor genes, which may be involved in the metastatic process of CRC, are located on chromosomes 8p21-22 and 18q21. Allelic losses in these regions are possible risk factors for lymph node metastasis of early CRC.     

Characteristics of insulin receptor binding to various rat tissues

The solution secondary structure of the Oxytricha nova telomeric 3' overhang, d(T4G4)2, has been investigated by Raman spectroscopy, hydrogen-deuterium exchange kinetics and gel electrophoresis. The electrophoretic mobility of d(T4G4)2 in non-denaturing gels indicates a highly compact conformation, consistent with a hairpin secondary structure. Raman markers show that the d(T4G4)2 hairpin contains equal numbers of C2'-endo/syn and C2'-endo/anti deoxyguanosine conformers, as well as G.G base-pairs of the Hoogsteen type. The hydrogen-deuterium exchange kinetics of d(T4G4)2, monitored by time-resolved Raman spectroscopy, reveal two kinetically distinct classes of guanine imino (N1H) protons. The more slowly exchanging fraction (kN1H(1)=4.6x10(-3) min-1), which represents 50% of N1H groups, is attributed to Hoogsteen-paired residues. The more rapidly exchanging fraction (kN1H(2)>/=0.3 min-1) is attributable to solvent-exposed residues. Raman dynamic probe of the kinetics of guanine C8H-->C8(2)H exchange in d(T4G4)2 reveals modest retardation vis-à-vis dGMP, which rules out quadruplex formation by the telomeric repeat and confirms an ordered secondary structure consistent with a Hoogsteen-paired hairpin. Similar Raman, hydrogen-isotope exchange and electrophoretic mobility experiments on the related telomeric model, dT6(T4G4)2, also reveal a hairpin stabilized by Hoogsteen G.G pairs. Presence of the 5' thymidine tail preceding the Oxytricha telomeric repeat has no apparent effect on the hairpin secondary structure. We propose a molecular model for the hairpin conformation of the Oxytricha nova telomeric repeat and consider its possible roles in mechanisms of telomeric DNA interaction in vitro and telomere function in vivo.