Steady and oscillatory fluid flows produce a similar osteogenic phenotype

Mechanical loading induces positive changes in the skeleton due to direct effects on bone cells, which may include regulation of transcription factors that support osteoblast differentiation and function. Flow effects on osteoblast transcription factors have generally been evaluated after short exposures. In this work, we assayed flow effects on osteogenic genes at early and late time points in a preosteoblast (CIMC-4) cell line and evaluated both steady and oscillatory flows. Four hours of steady unidirectional flow decreased the level of RANKL mRNA 53 ± 7% below that of nonflowed cells, but increases in Runx2 and osterix mRNA (44 ± 22% and 129 ± 12%, respectively) were significant only after 12-19 h of continuous flow. Late flow effects on RANKL and osterix were also induced by an intermittent flow-rest protocol (four cycles of 1 h on/1 h off + overnight rest). Four hours of oscillatory flow decreased RANKL mRNA at this early time point (63 ± 2%) but did not alter either osterix or Runx2. When oscillatory flow was delivered using the intermittent flow-rest protocol, Runx2 and osterix mRNA increased significantly (85 ± 19% and 161 ± 22%, respectively). Both β-catenin and ERK1/2, known to be involved in RANKL regulation, were rapidly activated by steady flow. Inhibition of flow-activated ERK1/2 prevented the increase in osterix mRNA but not Runx2; Runx2 phosphorylation was increased by flow, an effect which likely contributes to osterix induction. This work shows that both steady and oscillatory fluid flows can support enhancement of an osteogenic phenotype.

Design of a carbonic anhydrase IX active-site mimic to screen inhibitors for possible anticancer properties

Recently, a convincing body of evidence has accumulated suggesting that the overexpression of carbonic anhydrase isozyme IX (CA IX) in some cancers contributes to the acidification of the extracellular matrix, which in turn promotes the growth and metastasis of the tumor. These observations have made CA IX an attractive drug target for the selective treatment of certain cancers. Currently, there is no available X-ray crystal structure of CA IX, and this lack of availability has hampered the rational design of selective CA IX inhibitors. In light of these observations and on the basis of structural alignment homology, using the crystal structure of carbonic anhydrase II (CA II) and the sequence of CA IX, a double mutant of CA II with Ala65 replaced by Ser and Asn67 replaced by Gln has been constructed to resemble the active site of CA IX. This CA IX mimic has been characterized kinetically using (18)O-exchange and structurally using X-ray crystallography, alone and in complex with five CA sulfonamide-based inhibitors (acetazolamide, benzolamide, chlorzolamide, ethoxzolamide, and methazolamide), and compared to CA II. This structural information has been evaluated by both inhibition studies and in vitro cytotoxicity assays and shows a correlated structure-activity relationship. Kinetic and structural studies of CA II and CA IX mimic reveal chlorzolamide to be a more potent inhibitor of CA IX, inducing an active-site conformational change upon binding. Additionally, chlorzolamide appears to be cytotoxic to prostate cancer cells. This preliminary study demonstrates that the CA IX mimic may provide a useful model to design more isozyme-specific CA IX inhibitors, which may lead to development of new therapeutic treatments of some cancers.

Inhibition of experimental acute pulmonary inflammation by pirfenidone

Pirfenidone, a putative tumor necrosis factor-alpha (TNF-alpha) inhibitor, has recently gained recognition for its therapeutic use in the treatment of idiopathic pulmonary fibrosis. As pulmonary fibrosis may be the result of lung inflammatory processes, we examined the anti-inflammatory potential of pirfenidone in several models of acute pulmonary inflammation. In antigen-induced allergic paradigms, 24 h after antigen challenge, sensitized mice or guinea pigs develop a prominent pulmonary inflammation, reflected by a significant increase in the number of recoverable bronchoalveolar lavage (BAL) total cells and eosinophils. In both species, the pretreatment of animals with pirfenidone (10 and 30 mg/kg) resulted in a dose-dependent inhibition of the antigen-induced pulmonary inflammation, which was reflected by a significant decrease in the BAL eosinophils and total cells by the 30 mg/kg dose. In a non-allergic model of pulmonary inflammation, rats challenged with intratracheal LPS develop a significant increase in BAL neutrophils and total cells, along with significant increases in TNF-alpha and IL-6. Pretreatment with pirfenidone (3 and 30 mg/kg) showed a dose-dependent inhibition of the LPS-induced pulmonary inflammation, reflected by a significant decrease in the number of BAL total and neutrophilic cells at both the 3 and 30 mg/kg dose. However, pirfenidone had no effect on the peak BAL levels of TNF-alpha. In contrast, pirfenidone significantly inhibited BAL levels of IL-6. In summary, we have shown that pirfenidone can inhibit allergic and non-allergic inflammatory cell recruitment and that its pulmonary anti-inflammatory activity is independent of TNF-alpha inhibition.

Living alone after myocardial infarction. Impact on prognosis

OBJECTIVE

To determine if the presence of a disrupted marriage or living alone would be an independent prognostic risk factor for a subsequent major cardiac event following an initial myocardial infarction.

DESIGN

Prospective evaluation in the placebo wing of a randomized, double-blind drug trial in patients with an enzyme-documented acute myocardial infarction who were admitted to a coronary care facility. Data for living alone and/or a marital disruption were entered into a Cox proportional hazards model constructed from important physiologic and nonphysiologic factors in the same database.

SETTING

Multicenter trial in a mixture of community and academic hospitals in the United States and Canada.

PATIENTS

All consenting patients who were 25 to 75 years of age and without other serious diseases were enrolled (placebo, N = 1234) within 3 to 15 days of the index infarction and followed for a period of 1 to 4 years (mean, 2.1 years). Nine hundred sixty-seven patients were followed for 1.1 years and 530 for 2.2 years.

PRIMARY OUTCOME MEASURE

Recurrent major cardiac event (either recurrent nonfatal infarction or cardiac death).

RESULTS

Living alone was an independent risk factor, with a hazard ratio of 1.54 (95% confidence interval, 1.04 to 2.29; P less than .03). Using the Kaplan-Meier statistical method for calculation, the recurrent cardiac event rate at 6 months was 15.8% in the group living alone vs 8.8% in the group not living alone. Risk remained significant throughout the follow-up period (P = .001). A disrupted marriage was not an independent risk factor.

CONCLUSION

Living alone but not a disrupted marriage is an independent risk factor for prognosis after myocardial infarction when compared with all other known risk factors.

The dual-diagnosis patient in a psychiatric day treatment program: a treatment failure

This study was undertaken to determine the effectiveness of treating the dual-diagnosis patient in a standard psychiatric day treatment program. These patients, presenting with psychiatric disorder coexisting with alcohol and/or drug abuse, present a major problem in treatment because of their emotional fragility, their propensity to impulsive acting-out behaviors, and their adaptation to psychiatric symptomatology via self-medication with illicit drugs. Of the 24 dual-diagnosis patients admitted to our Day Treatment Center in 1988, 57% left treatment at or before 8 weeks following admission, as opposed to 21% of a nonsubstance abusing psychiatric control group. Their rate of absenteeism and suspensions for continuing abuse and infraction of the rules was four times that of the controls. In light of these data, it appears that these patients require highly specialized treatment strategies not generally available in a conventional psychiatric day hospital.

Effect of verapamil and other agents on the distribution of anthracyclines and on reversal of drug resistance

We studied the intracellular distribution of drugs within anthracycline-sensitive and -resistant cells by computer-assisted digitized video fluorescence microscopy. We found that the antitumor antibiotic, daunorubicin, distributes differently in anthracycline-sensitive and -resistant human leukemia cells (HL-60). Verapamil and other agents known to circumvent resistance in pleiotropic drug-resistant cell lines were able to change the pattern of distribution of daunorubicin in the anthracycline-resistant HL-60 cells back to the distribution found in anthracycline-sensitive HL-60 cells. To investigate the biochemical basis for this effect, we studied the distribution of daunorubicin and doxorubicin in a hydrophobic/hydrophilic (membrane/cytoplasmic) environment using the two-compartment cell-free system of Folch. Our results demonstrate that various unrelated drugs known to overcome resistance will also change the distribution of the anthracyclines in the hydrophobic/hydrophilic compartments. Our data allow the hypothesis that various unrelated agents known to circumvent resistance may act by altering the hydrophobic/hydrophilic solubility of anthracyclines in the resistant cell.

Acute renal failure in idiopathic nephrotic syndrome

In 4 adults with idiopathic nephrotic syndrome an acute renal failure with prolonged anuria has been observed. At renal histology 1 patient showed minimal glomerular changes and 3 showed focal glomerulosclerosis. No vascular abnormalities were seen. In all cases severe tubular lesions with casts and cell debris in the lumina were observed. In 2 patients renal function improved after 3 and 6 months, respectively; the remaining 2 died after several months from the onset of acute renal failure being still anuric. Although the pathogenesis of this complication is unknown, tubular obstruction by proteinaceous casts and vasoconstriction may play an important role. The prognosis of this complication is severe, but the possibility of spontaneous recovery even after protracted anuria cannot be ruled out.