Differential nitric oxide and TNF-alpha production of murine Kupffer cell subfractions upon priming with IFN-gamma and TNF-alpha

The effects of a nitric oxide (NO) donor on microcirculation and contractile function of reperfused skeletal muscle were studied. Rat cremaster muscles underwent 5 hours of ischemia and 90 minutes of reperfusion and were divided into two groups systemically infused with S-nitroso-N-acetylcysteine (SNAC, 100 nmol/min) and phosphate-buffered saline (PBS), respectively. The results showed that the vessels in the SNAC group had more rapid and complete recovery than that in controls. A significant difference was found from 10 to 40 minutes and at 90 minutes in 10-20-microm arterioles, from 10 to 90 minutes in 20-40-microm arterioles, and at 10 and 90 minutes in 40-70-microm arteries. When compared to controls, SNAC-treated muscles showed larger fluorescein filling areas at 15, 30, 60, and 90 minutes and greater isometric tetanic contractile forces in response to stimulation frequencies of 40, 70, 100, and 120 Hz. The data indicate that supplementation of exogenous NO could effectively improve microcirculation and contractile function of skeletal muscle during early reperfusion.     

Tuft-to-capsule adhesions and their precursors: differences between the vascular and tubular poles of the human glomerulus

The hypothalamo-pituitary-adrenal (HPA) axis is modulated by sex hormones. Few data exist on the relation between acute estrogen deficit and HPA axis response to corticotropin-releasing hormone (CRH). The effects of a sudden drop in estradiol levels on basal and CRH-stimulated levels of ACTH, cortisol, testosterone, androstenedione and 17-hydroxyprogesterone (17-OHP) were assessed in nine premenopausal women (44-48 years of age), before and after ovariectomy. The CRH test was performed before and 8 days after ovariectomy. A significant reduction in ACTH and adrenal steroids but not in cortisol response to CRH was observed after ovariectomy. The ratio of deltamax androstenedione/17-OHP after CRH stimulation was substantially the same before and after ovariectomy, whereas deltamax 17-OHP/cortisol was significantly lower in ovariectomized women showing increased 21- and 11beta-hydroxylase activity. The results show that the acute estrogen deficit induces changes in the HPA axis characterized by reduced stimulated secretion of ACTH and steroids but normal stimulated cortisol production.     

Provision of taxoids in 1996: inequality of care

OBJECTIVE: To inventory the utilization of taxoids in 1996. METHODS: A survey was conducted in february 1997 among the medical heads of 130 Dutch hospitals. The questions about the use of taxoids (paclitaxel and docetaxel) in 1996 concerned indications, numbers of patients treated, the funding and possible financial restrictions on the treatment. Three weeks after the mailing of the questionnaire, a reminder was sent to hospitals that had not responded. The data from 120 hospitals where oncological care was administered were analysed. RESULTS: Of the 120 hospitals, 111 (92.5%) returned the questionnaire, from 114 locations. Twelve locations reported not having used taxoids, four of them partly for financial reasons. Taxoids had been used at 102 locations: at the expense of the hospital budget at 101 locations, and exclusively at the expense of sickness insurers at one location. At 27 locations, paclitaxel and docetaxel had also been issued in the context of trials, and at 7 locations also via special agreements with the insurers and (or) at the expense of the patient himself. Fifty-three of the 102 taxoid using hospitals had a financial upper limit or a maximum number of patients to be treated. Eighteen of the 102 locations where paclitaxel or docetaxel was issued reported that for financial reasons not all patients eligible for taxoids had been given these drugs. The indications varied from one hospital to another: 67 locations used them for first-phase treatment of patients with ovarian carcinoma, 96 locations for second-phase treatment of patients with ovarian carcinoma and at 91 locations, patients with mammary carcinoma were given taxoids when anthracyclines were no longer indicated. CONCLUSION: Hospitals in 1996 varied greatly with regard to issuing of taxoids. This diversity in part had financial causes. Restrictions on the issuing of taxoids for financial reasons lead to unequal access to care.     

RNA-binding proteins tamed

OBJECTIVES: Enhancement of the remineralisation of artificial enamel lesions has been observed in an intraoral model whether subjects chewed gum sweetened with a non-cariogenic sweetener such as sorbitol [1-3] or sucrose [4] after meals or snacks, and with use of a conventional (1500 ppm F) fluoride dentifrice. Since most of the clinical surveys which have shown the potential cariogenicity of sucrose chewing gum [5] were conducted before use of fluoridated dentifrices became widespread, the effect of fluoride dentifrice on de- and remineralisation of artificial lesions in enamel in response to chewing sucrose-sweetened gum has been examined with the aim of attempting to resolve this apparent discrepancy. METHODS: Subjects wore an intraoral device bearing an enamel lesion and chewed one piece of sucrose gum for 20 min after each of three meals and two snacks daily for two 3-week periods, during which they used a dentifrice containing either 0 or 1500 ppm F in a double-blind, cross-over design. Measurement of the mineral content of the lesions was determined by microradiography or polarised light microscopy. RESULTS: It was found that remineralisation tended to occur with 1500 ppm F dentifrice, but demineralisation with non-F dentifrice; the difference in enamel mineral content between the two periods was significant (P < 0.05). CONCLUSIONS: The results indicate that the potential cariogenicity of sucrose-containing chewing gum may indeed be negated by the use of a conventional fluoride dentifrice.     

Fibroblast-like cells from tendons differ from skin fibroblasts in their ability to form three-dimensional structures in vitro

Recent structural information suggests that the HC(X)5R active-site motif defines three distinct evolutionary families of phosphatases that employ a common catalytic mechanism. In two instances, regulation of phosphatase activity employs autoinhibitory mechanisms involving either intermolecular or intramolecular interactions, whereby inhibition is mediated by sterically blocking the active-site cleft.     

A search method for homologs of small proteins. Ubiquitin-like proteins in prokaryotic cells?

The question of protein homology versus analogy arises whenproteins share a common function or a common structural foldwithout any statistically significant amino acid sequence similarity.Even though two or more proteins do not have similar sequencesbut share a common fold and the same or closely related function,they are assumed to be homologs, descendant from a common ancestor.The problem of homolog identification is compounded in the caseof proteins of 100 or less amino acids. This is due to a limitednumber of basic single domain folds and to a likelihood of identifyingby chance sequence similarity. The latter arises from two conditions:first, any search of the currently very large protein databaseis likely to identify short regions of chance match; secondly,a direct sequence comparison among a small set of short proteinssharing a similar fold can detect many similar patterns of hydrophobicityeven if proteins do not descend from a common ancestor. In aneffort to identify distant homologs of the many ubiquitin proteins,we have developed a combined structure and sequence similarityapproach that attempts to overcome the above limitations ofhomolog identification. This approach results in the identificationof 90 probable ubiquitin-related proteins, including examplesfrom the two prokaryotic domains of life, Archaea and Bacteria. Received December 1, 2002; revised October 22, 2003; accepted October 24, 2003     

Mutational analysis of potential zinc-binding residues in the active site of the enterococcal D-Ala-D-Ala dipeptidase VanX

VanX, one of the five proteins required for the vancomycin-resistant phenotype in clinically pathogenic Enterococci, is a zinc-containing d-Ala-d-Ala dipeptidase. To identify potential zinc ligands and begin defining the active site residues, we have mutated the 2 cysteine, 5 histidine, and 4 of the 28 aspartate and glutamate residues in the 202 residue VanX protein. Of 10 mutations, 3 cause inactivation and greater than 90% loss of zinc in purified enzyme samples, implicating His116, Asp123, and His184 as zinc-coordinating residues. Homology searches using the 10 amino acid sequence SxHxxGxAxD, in which histidine and aspartate residues are putative zinc ligands, identified the metal coordinating ligands in the N-terminal domain of the murine Sonic hedgehog protein, which also exhibits an architecture for metal coordination identical to that observed in thermolysin from Bacillus thermoproteolyticus. Furthermore, this 10 amino acid consensus sequence is found in the Streptomyces albus G zinc-dependent N-acyl-d-Ala-d-Ala carboxypeptidase, an enzyme catalyzing essentially the same d-Ala-d-Ala dipeptide bond cleavage as VanX, suggesting equivalent mechanisms and zinc catalytic site architectures. VanX residue Glu181 is analogous to the Glu143 catalytic base in B. thermoproteolyticus thermolysin, and the E181A VanX mutant has no detectable dipeptidase activity, yet maintains near-stoichiometric zinc content, a result consistent with the participation of the residue as a catalytic base.     

Lobular carcinoma of the breast: cytological features supporting the diagnosis of lobular cancer

Lobular carcinomas have a distinct natural history with a better response to endocrine therapy and a higher incidence of local recurrence and are more often bilateral. The cytological diagnosis of lobular carcinoma permits a discriminating therapeutic approach with pre-operative Tamoxifen, more generous resection margins, and assessment of the contralateral breast. The cytological features of lobular cancer however are not well defined and the low cell yield from such neoplasms can result in a high false negative rate. To determine whether we could improve the pre-operative diagnosis, we reviewed the cytological features of 112 lobular carcinomas. They had small uniform sized nuclei with irregular outlines and inconspicuous nucleoli. The degree of dissociation was similar to duct carcinomas and the incidence of inadequate aspirates was no higher. We found no features that confidently diagnosed lobular cancer or its sub-types. However, using a combination of features, typing of lobular cancer on aspirated material is possible and should be attempted.     

Effects of age, sex, and ethnicity on the association between apolipoprotein E genotype and Alzheimer disease. A meta-analysis. APOE and Alzheimer Disease Meta Analysis Consortium

OBJECTIVE: To examine more closely the association between apolipoprotein E (APOE) genotype and Alzheimer disease (AD) by age and sex in populations of various ethnic and racial denominations. DATA SOURCES: Forty research teams contributed data on APOE genotype, sex, age at disease onset, and ethnic background for 5930 patients who met criteria for probable or definite AD and 8607 controls without dementia who were recruited from clinical, community, and brain bank sources. MAIN OUTCOME MEASURES: Odds ratios (ORs) and 95% confidence intervals (CIs) for AD, adjusted for age and study and stratified by major ethnic group (Caucasian, African American, Hispanic, and Japanese) and source, were computed for APOE genotypes epsilon2/epsilon2, epsilon2/epsilon3, epsilon2/epsilon4, epsilon3/epsilon4, and epsilon4/epsilon4 relative to the epsilon3/epsilon3 group. The influence of age and sex on the OR for each genotype was assessed using logistic regression procedures. RESULTS: Among Caucasian subjects from clinic- or autopsy-based studies, the risk of AD was significantly increased for people with genotypes epsilon2/epsilon4 (OR=2.6, 95% CI=1.6-4.0), epsilon3/epsilon4 (OR=3.2, 95% CI=2.8-3.8), and epsilon4/epsilon4 (OR=14.9, 95% CI= 10.8-20.6); whereas, the ORs were decreased for people with genotypes epsilon2/epsilon2 (OR=0.6, 95% CI=0.2-2.0) and epsilon2/epsilon3 (OR=0.6, 95% CI=0.5-0.8). The APOE epsilon4-AD association was weaker among African Americans and Hispanics, but there was significant heterogeneity in ORs among studies of African Americans (P<.03). The APOE epsilon4-AD association in Japanese subjects was stronger than in Caucasian subjects (epsilon3/epsilon4: OR=5.6, 95% CI=3.9-8.0; epsilon4/epsilon4: OR=33.1, 95% CI=13.6-80.5). The epsilon2/epsilon3 genotype appears equally protective across ethnic groups. We also found that among Caucasians, APOE genotype distributions are similar in groups of patients with AD whose diagnoses were determined clinically or by autopsy. In addition, we found that the APOE epsilon4 effect is evident at all ages between 40 and 90 years but diminishes after age 70 years and that the risk of AD associated with a given genotype varies with sex. CONCLUSIONS: The APOE epsilon4 allele represents a major risk factor for AD in all ethnic groups studied, across all ages between 40 and 90 years, and in both men and women. The association between APOE epsilon4 and AD in African Americans requires clarification, and the attenuated effect of APOE epsilon4 in Hispanics should be investigated further.