Faculty Bibliography

Simulated supracondylar fractures were created proximal to posterior cruciate ligament-retaining total knee arthroplasty components in paired human cadaver femora and stabilized with either a retrograde-inserted locked supracondylar nail or the Less Invasive Stabilization System (LISS; Synthes USA, Paoli, PA). Loads were applied to create bending and torsional moments on the simulated fracture stabilized with either no gap or a 10-mm gap. The LISS exhibited less torsional stability with anterior (P<.001) and posterior loads (P<.01). When varus loads were applied to 10-mm-gap specimens, the specimens stabilized with a retrograde nail had an 83% reduction in fracture displacement (P<.001) and 80% less medial translation of the distal fragment (P<.001). The samples stabilized with the LISS had a 93% reduction in fracture gap displacement when a valgus load was applied with a 10-mm gap (P<.001). Overall, these results suggest that the retrograde-inserted nail may provide greater stability for the management of periprosthetic supracondylar femur fractures in patients with a posterior cruciate ligament-retaining femoral total knee arthroplasty component

It is important to determine how the signaling pathways for the short-term effects of nicotine (catecholamine secretion, phosphorylation of tyrosine hydroxylase) differ from those required for changes in gene expression. Our aim was to distinguish the pathways involved in short- and long-term nicotinic stimulation. PC12 cells were treated with several concentrations of nicotine from 10 micro M to 1 mM. All elicited a rapid and transient rise in [Ca(2+)](i), which was concentration dependent. After several minutes of continued exposure, a second smaller sustained rise in [Ca(2+)](i) was only observed with intermediate concentrations of nicotine (50-200 micro M). This sustained rise was not observed in cells pretreated with alpha-bungarotoxin (alpha-BTX). alpha-BTX also prevented the elevation of tyrosine hydroxylase mRNA by nicotine. The effects of brief and prolonged treatment with nicotine on the signaling pathways involved in changes in [Ca(2+)](i) and induction of tyrosine hydroxylase gene expression are summarized. The results indicate that nicotine may elicit different signaling pathways depending on the concentration. The sustained elevation of [Ca(2+)](i) via activation of alpha7 nAChRs is proposed as the mechanism leading to increased tyrosine hydroxylase gene expression.

Directed migration of keratinocytes is essential for wound healing. The migration of human keratinocytes in vitro is strongly influenced by the presence of a physiological electric field and these cells migrate towards the negative pole of such a field (galvanotaxis). We have previously shown that the depletion of extracellular calcium blocks the directional migration of cultured human keratinocytes in an electric field (Fang et al., 1998; J Invest Dermatol 111:751-756). Here we further investigate the role of calcium influx on the directionality and migration speed of keratinocytes during electric field exposure with the use of Ca(2+) channel blockers. A constant, physiological electric field strength of 100 mV/mm was imposed on the cultured cells for 1 h. To determine the role of calcium influx during galvanotaxis we tested the effects of the voltage-dependent cation channel blockers, verapamil and amiloride, as well as the inorganic Ca(2+) channel blockers, Ni(2+) and Gd(3+) and the Ca(2+) substitute, Sr(2+), on the speed and directionality of keratinocyte migration during galvanotaxis. Neither amiloride (10 microM) nor verapamil (10 microM) had any effect on the galvanotaxis response. Therefore, calcium influx through amiloride-sensitive channels is not required for galvanotaxis, and membrane depolarization via K(+) channel activity is also not required. In contrast, Sr(2+) (5 mM), Ni(2+) (1-5 mM), and Gd(3+) (100 microM) all significantly inhibit the directional migratory response to some degree. While Sr(2+) strongly inhibits directed migration, the cells exhibit nearly normal migration speeds. These findings suggest that calcium influx through Ca(2+) channels is required for directed migration of keratinocytes during galvanotaxis and that directional migration and migration speed are probably controlled by separate mechanisms

In Drosophila, differences between segments, such as the presence or absence of appendages, are controlled by Hox transcription factors. The Hox protein Ultrabithorax (Ubx) suppresses limb formation in the abdomen by repressing the leg selector gene Distalless, whereas Antennapedia (Antp), a thoracic Hox protein, does not repress Distalless. We show that the Hox cofactors Extradenticle and Homothorax selectively enhance Ubx, but not Antp, binding to a Distalless regulatory sequence. A C-terminal peptide in Ubx stimulates binding to this site. However, DNA binding is not sufficient for Distalless repression. Instead, an additional alternatively spliced domain in Ubx is required for Distalless repression but not DNA binding. Thus, the functional specificities of Hox proteins depend on both DNA binding-dependent and -independent mechanisms

Mitochondrial dysfunction and oxidative stress have been implicated in cellular senescence, apoptosis, aging and aging-associated pathologies. Telomere shortening and genomic instability have also been associated with replicative senescence, aging and cancer. Here we show that mitochondrial dysfunction leads to telomere attrition, telomere loss, and chromosome fusion and breakage, accompanied by apoptosis. An antioxidant prevented telomere loss and genomic instability in cells with dysfunctional mitochondria, suggesting that reactive oxygen species are mediators linking mitochondrial dysfunction and genomic instability. Further, nuclear transfer protected genomes from telomere dysfunction and promoted cell survival by reconstitution with functional mitochondria. This work links mitochondrial dysfunction and genomic instability and may provide new therapeutic strategies to combat certain mitochondrial and aging-associated pathologies

BACKGROUND: The senescence-accelerated mouse (SAM) has been shown to exhibit ageing-associated mitochondrial dysfunction and oxidative stress, and early decline in fertility. METHODS: We compared meiotic progression of germinal vesicle oocytes between young (2-3 months) and old (10-14 months) SAM mice using triple immunostaining and fluorescence microscopy as well as Pol-Scope imaging. RESULTS: At 8-9 h of in-vitro maturation (IVM), most young SAM oocytes (86%, 32/37) were at meiosis I (MI) stage, with chromosomes aligned in the mid-region of MI spindles, whereas disrupted MI spindles and/or chromosome misalignments (45%, 18/40) and a few oocytes (20%, 8/40) with abnormal MII spindles were found in old SAM oocytes. At 15-17 h of IVM, old SAM oocytes, despite errors at MI stage, extruded a first polar body at an incidence of 88% (n = 85), which did not differ from that (92%, n = 106) of young SAM oocytes. However, oocytes from old SAM (64%, 32/50) showed aberrant MII, with chromosome misalignment and dispersal, in contrast to normal MII in most young SAM oocytes (87%, 65/75), showing chromosome alignment at the metaphase plate of MII spindles. Moreover, Pol-Scope imaging non-invasively detected disrupted or absent visible spindles and possibly aberrant chromosome alignment. CONCLUSIONS: Spindle disruption and/or chromosome misalignments at both MI and MII are associated with maternal ageing in the SAM mouse. Our findings also suggest that meiotic division lacks a competent checkpoint for spindle integrity and chromosome alignment during reproductive ageing-associated oocyte senescence

Sex steroids play important and diverse roles in the regulation of structure and function of the central nervous system. Early in life, steroids shape the structure of sensitive areas of the brain, especially those involved in the control of reproductive behavior and ovarian function. Original studies demonstrating organizing effects of steroids on the brain were carried out in rodents, but more recently these studies have been extended to primates, including humans. Throughout life, sex steroids regulate neural function by influencing steroid receptor-bearing neurons and by influencing neurons via steroid receptor-independent mechanisms. Sex steroid receptors have been identified in the brain, especially in the phylogenetically ancient structures that regulate reproductive behavior. Sex steroids that affect neural function can originate peripherally from the brain and/or adrenal gland, and can be synthesized within the brain itself. A number of neurally active progestogens and androgens are synthesized de novo in the brain, and estrogens can be converted within the brain from androgens by the enzyme aromatase. Thus, ovarian and central nervous system sex steroids play important roles in regulating reproductive behavior by regulating neural structure and function

To determine estrogen effects on osmotic regulation of arginine vasopressin (AVP) and body fluids, we suppressed endogenous estrogen and progesterone using the gonadotropin-releasing hormone (GnRH) analog leuprolide acetate (GnRHa). Subjects were assigned to one of two groups: 1) GnRHa alone, then GnRHa + estrogen (E, n = 9, 25 +/- 1 yr); 2) GnRHa alone, then GnRHa + estrogen with progesterone (E/P, n = 6, 26 +/- 3). During GnRHa alone and with hormone treatment, we compared AVP and body fluid regulatory responses to 3% NaCl infusion (HSI, 120 min, 0.1 ml. min(-1). kg body wt(-1)), drinking (30 min, 15 ml/kg body wt), and recovery (60 min of seated rest). Plasma [E(2)] increased from 23.9 to 275.3 pg/ml with hormone treatments. Plasma [P(4)] increased from 0.6 to 5.7 ng/ml during E/P and was unchanged (0.4 to 0.6 ng/ml) during E. Compared with GnRHa alone, E reduced osmotic AVP release threshold (275 +/- 4 to 271 +/- 4 mosmol/kg, P < 0.05), and E/P reduced the AVP increase in response during HSI (6.0 +/- 1.3 to 4.2 +/- 0.6 pg/ml at the end of HSI), but free water clearance was unaffected in either group. Relative to GnRHa, pre-HSI plasma renin activity (PRA) was greater during E (0.8 +/- 0.1 vs. 1.2 +/- 0.2 ng ANG I. ml(-1). h(-1)) but not after HSI or recovery. PRA was greater than GnRHa during E/P at baseline (1.1 +/- 0.2 vs. 2.5 +/- 0.6) and after HSI (0.6 +/- 0.1 vs. 1.1 +/- 1.1) and recovery (0.5 +/- 0.1 vs. 1.3 +/- 0.2 ng ANG I. ml(-1). h(-1)). Baseline fractional excretion of sodium was unaffected by E or E/P but was attenuated by the end of recovery for both E (3.3 +/- 0.6 vs. 2.4 +/- 0.4%) and E/P (2.8 +/- 0.4 vs 1.7 +/- 0.4%, GnRHa alone and with hormone treatment, respectively). Fluid retention increased with both hormone treatments. Renal sensitivity to AVP may be lower during E due to intrarenal effects on water and sodium excretion. E/P increased sodium retention and renin-angiotensin-aldosterone stimulation

Since the 1990s, the substantial increase in the rate of Candida glabrata infections has become a serious problem. As most C. glabrata infections arise from the host's endogenous microflora, the present prospective, multicenter analysis included all clinical isolates associated with colonization and with systemic and hematogenous candidiasis. Among 347 C. glabrata isolates, the overall rates of resistance to fluconazole (MIC > or = 64 micro g/ml) and itraconazole (MIC > or = 1 micro g/ml) were 10.7 and 15.2%, respectively, although for half (n = 148) of the itraconazole-susceptible isolates the MICs (0.25 to 0.5 micro g/ml) were in the susceptible-dependent upon dose range. Fluconazole resistance was more common among C. glabrata isolates obtained from centers caring for patients with cancer (MICs at which 90% of isolates are inhibited [MIC(90)s] = 32 micro g/ml) or AIDS (MIC(90)s > 64 micro g/ml) than among C. glabrata isolates from a community-based university medical center (MIC(90)s = 16 micro g/ml) (P = 0.001). Thirty-three bloodstream isolates and those obtained from other body sites had similar in vitro susceptibility profiles. The fluconazole MIC(90)s (< or =16 micro g/ml) for C. glabrata yeast isolates from the gastrointestinal tract were lower than those (> or =64 micro g/ml) for C. glabrata isolates from respiratory and urinary tract samples (P = 0.01). A similar discrepancy for itraconazole was not significant (P > 0.5). We did not observe differences in fluconazole or itraconazole susceptibility profiles among C. glabrata isolates associated with either hematogenous dissemination or colonization. The significant discrepancy in antifungal susceptibility among C. glabrata organisms isolated from hospitals in the same geographic region emphasizes the significance of periodic susceptibility surveillance programs for individual institutions, especially those providing care to patients at risk

PURPOSE: To investigate histopathologic changes in human meibomian gland. METHODS: Human meibomian gland samples were obtained at autopsy from 50 men and 33 women aged from 17 to 87 years with a mean age (+/- SD) of 61 +/- 13 years. Pieces of tarsal plate measuring 3 x 3 mm including meibomian glands were excised from the center of both upper eyelids, then fixed and embedded in paraffin. Sections 4-microm thick were stained with hematoxylin and eosin and periodic acid-Schiff. Light microscopy was used to observe any histopathologic changes. RESULTS: The following histopathologic changes were observed: (1) cystic dilatation of acini and/or ducts, (2) atrophy of acini, (3) basement membrane thickening of acini, (4) granulation tissue, and (5) lipogranulomatous inflammation. CONCLUSION: Various histopathologic changes were observed in the human meibomian gland. Hyperkeratinization of ductal epithelium and atrophy of acinar cells may cause meibomian gland dysfunction.