Regulation of osteoblast gene expression and phenotype by polylactide-fatty acid surfaces.

Cell function is influenced by surface structure and molecules. Molecules that enhance cellular differentiation can be applied to tissue scaffold surfaces to stimulate endogenous tissue regeneration. The application of this approach to bone implants yields surfaces coated with factors (proteins, peptides, etc...) that promote the differentiation of osteoblasts, the cells that make bone. Increased bone formation leads to increased healing and union of the implant with endogenous bone. To obtain better control over surface coating we developed PLLA copolymers with allyl (PLLA-co-DAG) and 3-hydroxypropyl (PLLA-co-HP) side chains to which we can attach functional groups. Given the potential of fatty acids being able to incorporate into lipid bilayers and/or influence gene expression, we grafted different fatty acid side chains to PLLA-co-HP by esterifying the corresponding fatty acids with the PLLA-co-HP 3-hydroxypropyl side chains. The effects of the polymer modifications on osteoblasts were then evaluated. While cellular morphology differed between surface coatings, they did not reflect changes in cellular phenotype. Changes in gene expression were most evident with arachidonate and 3-hydroxypropyl side-chains which exhibited osteoblast differentiating capabilities. Linoleate, myristate, oleate, and stearate ester side-chains did not have a significant influence on osteoblast phenotype. Growth characteristics of osteoblasts did not differ between the fatty acid copolymer films, although cells grown on PLLA-co-HP exhibited a trend toward increased growth. Taken together our findings demonstrate that surface fatty acid composition can impact osteoblast phenotype.

The remodelled tracheal basement membrane zone of infant rhesus monkeys after 6 months of recovery.

BACKGROUND: In previous studies, we showed that repeated exposure to (1) house dust mite allergen (HDMA) (Dermatophagoides farinae) caused thickening of the basement membrane zone (BMZ) and (2) HDMA+ozone (O3) caused depletion of BMZ perlecan and atypical development of BMZ collagen (irregular thin areas<2.0 microm in width). OBJECTIVE: The purpose of this study was to determine if these remodelling changes were reversible after 6 months of recovery. METHODS: Rhesus monkeys were exposed to a regimen of HDMA and or O3 or filtered air (FA) for 6 months. After the exposure protocol was completed FA and O3 groups were allowed to recover in FA for 6 months. The HDMA and HDMA+O3 exposure groups recovered in a modified environment. They were re-exposed to HDMA aerosol for 2 h at monthly intervals during recovery in order to maintain sensitization for pulmonary function testing. To detect structural changes in the BMZ, collagen I and perlecan immunoreactivity were measured and compared to data from the previous papers. RESULTS: The remodelled HDMA group had a significantly thicker BMZ and after 6 months of recovery the width had not regressed. In the remodelled BMZ of the HDMA+O3 group, perlecan had returned to the BMZ after 6 months of the recovery protocol, and the thin, irregular, collagen BMZ had been resolved. CONCLUSION: In summary, this study has shown that: (1) The width of the remodelled HDMA BMZ did not regress during a recovery protocol that included a sensitizing dose of HDMA. (2) The atypical collagen BMZ in the HDMA+O3 BMZ was resolved in the absence of O3. (3) Depletion of perlecan from the BMZ by O3 was reversed by recovery in the absence of O3.

Poly(phenyllactide): synthesis, characterization, and hydrolytic degradation.

Poly(phenyllactide) was synthesized via the ring-opening polymerization of phenyllactide, the dimer of phenyllactic acid. Phenyllactide was synthesized by two methods, the solution phase condensation of L-phenyllactic acid and by thermal cracking of low molecular weight phenyllactic acid oligomers. The poor solubility of the monomer limited solution polymerizations of phenyllactide to low yields and low molecular weights, but melt polymerization of phenyllactide with Sn(Oct)2/tert-butylbenzyl alcohol at 180 degrees C gave high molecular weight polymers in high yields. The resulting polymers were amorphous due to epimerization of approximately 10% of the stereocenters during polymerization. Poly(phenyllactide) has a glass transition temperature of 50 degrees C and degrades to monomer at 320 degrees C. Experiments run at 55 degrees C at pH 7.4 show that poly(phenyllactide) degrades at approximately 1/5 the rate of rac-polylactide.

High doses of intravenous immunoglobulin G enhance Kupffer cell phagocytic function during the late phase of sepsis and endotoxemia in rats.

The effect of intravenous immunoglobuln G (ivIG) on the hepatic microvascular inflammatory response during the late phase of sepsis and endotoxemia in rats was studied by using in vivo microscopy. One hour after administration of a clinically relevant dose of ivIG (0.5 g/kg body weight, Sandoglobulin), rats were subjected to polymicrobial sepsis induced by cecal ligation and puncture (CLP) or were injected intravenously with lipopolysaccharide (LPS, 0.1 mg/kg body weight). Twenty-four hours after CLP or LPS, the number of leukocytes adhering to the sinusoidal wall was increased 11.0-fold in CLP-treated animals and 5.6-fold in LPS-treated animals, respectively, compared with the controls. Concomitantly, the numbers of swollen sinusoidal endothelial cells were increased 4.2-fold and 3.2-fold. The number of perfused sinusoids was decreased by 35% and by 24%. These responses were minimized by pretreatment with high doses of ivIG. Kupffer cell phagocytic activity in the periportal sinusoids in CLP-treated animals was decreased by 41%, whereas that in the centrilobular sinusoids in LPS-treated animals was increased by 72%. IvIG significantly elevated this activity in both CLP- and LPS-treated animals and the number of ED2-positive Kupffer cells in tissue sections. The results suggest that ivIG limits the hepatic microvascular inflammatory response during the late phase of sepsis and endotoxemia by affecting Kupffer cell function.

cdk6 can shorten G(1) phase dependent upon the N-terminal INK4 interaction domain.

Deregulated activity of cdk4 or cdk6 can lead to inappropriate cellular proliferation and tumorigenesis accompanied by unchecked inactivation of the retinoblastoma tumor suppressor protein. Certain tumor types preferentially activate either cdk4 or cdk6, suggesting that these kinases may not be equivalently oncogenic in all cell types. Although it is clear that cdk4 can act as an oncogene at least in part by evading inhibition by p16(INK4a), the role of cdk6 in tumorigenesis is less well understood. To investigate the consequences of aberrant expression of cdk6, the requirements for proliferation caused by cdk6 overexpression were studied. cdk6-transfected U2OS cells displayed an accelerated progression through G(1) phase that was dependent on kinase activity and that did not correlate with p27 binding. Furthermore, a mutation that prevents cdk6 interaction with INK4 proteins (cdk6R31C) was found to inactivate the proliferative effect of cdk6 and increase cytoplasmic localization, despite the fact that this mutant could phosphorylate the retinoblastoma protein in vitro. Together, these data suggest a role for the cdk6 INK4 interaction domain in the generation of functional, nuclear cdk6 complexes and demonstrate the importance of elevated cdk6 kinase activity in G(1) acceleration.

Effect of intravenous immunoglobulin G on the TNFalpha-mediated hepatic microvascular inflammatory response.

The effect of intravenous immunoglobulin G (ivIG) on the hepatic microvascular inflammatory response elicited by tumor necrosis factor alpha (TNFalpha) in rats was studied by means of in vivo microscopy and histological examination. One hour after the portal infusion of TNFalpha, the average number of leukocytes adhering to the sinusoidal endothelium was increased sevenfold, and the average number of the perfused sinusoids was decreased by 15% when compared with controls. Concomitantly, the expression of intercellular adhesion molecule-1 (ICAM-1) on the hepatic sinusoidal endothelium and that of the central vein was increased. The phagocytic activity of Kupffer cells in centrilobular sinusoids was increased by 54%, as were the number of ED2-positive Kupffer cells in tissue sections. Pretreatment with a clinically relevant high dose of ivIG (1 g/kg body weight, Sandoglobulin) minimized these responses by reducing leukocyte-endothelial interactions and Kupffer cell phagocytic function. The results suggest that high doses of ivIG limit the hepatic microvascular inflammatory response by inhibiting the action of the proinflammatory cytokine TNFalpha.

Inverting chaos: Extracting system parameters from experimental data.

Given a set of experimental or numerical chaotic data and a set of model differential equations with several parameters, is it possible to determine the numerical values for these parameters using a least-squares approach, and thereby to test the model against the data? We explore this question (a) with simulated data from model equations for the Rossler, Lorenz, and pendulum attractors, and (b) with experimental data produced by a physical chaotic pendulum. For the systems considered in this paper, the least-squares approach provides values of model parameters that agree well with values obtained in other ways, even in the presence of modest amounts of added noise. For experimental data, the "fitted" and experimental attractors are found to have the same correlation dimension and the same positive Lyapunov exponent. (c) 1996 American Institute of Physics.

Effect of immunoglobulin G on the hepatic microvascular inflammatory response during sepsis.

The effects of intravenous immunoglobulin G (ivIG) on the hepatic microvascular inflammatory response to sepsis were studied in rats by in vivo microscopy. High doses of ivIG (300 mg/kg bw) (Sandoglobulin or rat IgG) significantly improved the 48 h survival of septic rats from 25-66% when ivIG was given before or immediately after cecal ligation and puncture. Circulating endotoxin also was significantly reduced. Eight hours after inducing sepsis, the average number of leukocytes adhering to the sinusoidal endothelium increased 15-fold and the average decrease in the number of perfused sinusoids was 22%. IvIG administration minimized these responses. In both septic and nonseptic animals, ivIG also reduced the phagocytic activity of Kupffer cells. The results suggest that high doses of ivIG not only reduce lethality but also limit hepatic microcirculatory dysfunction during sepsis by minimizing leukocyte-endothelial interactions that may be a result of reducing circulating endotoxin and modifying Kupffer cell function.

Effects of cyclophosphamide on the development of malignancy and on long-term survival of patients with rheumatoid arthritis. A 20-year followup study.

OBJECTIVE: To examine the effects of cyclophosphamide (CYC) on the development of malignancies and on the long-term survival of patients with rheumatoid arthritis (RA). METHODS: We used a longitudinal cohort design in which 119 patients (76 women and 43 men) with refractory RA who were treated with oral CYC between 1968 and 1973 were compared with 119 control patients with RA (matched for age, sex, disease duration, and functional class) who were evaluated during the same time period but did not receive CYC. RESULTS: There was increased risk of malignancy in the CYC-treated group, with 50 cancers found in 37 patients in the CYC group compared with 26 cancers in 25 of the control patients (P < 0.05). The relative risk of cancer for those treated with CYC was 1.5 (95% confidence interval 0.93-5.5). Nine of the malignancies in the CYC group were bladder cancers and 19 were skin cancers, compared with no bladder cancers and 6 skin cancers in the control group. The total dose of CYC was higher in those who developed cancer, particularly in those with bladder cancer. Three of the bladder cancers occurred 14, 16, and 17 years after CYC had been discontinued. CONCLUSION: The risk of malignancy, particularly bladder cancer, in RA patients treated with oral CYC continues even 17 years after discontinuation of the drug.

Role of endotoxin in the hepatic microvascular inflammatory response to ethanol.

Kupffer cells (KC) and gut-derived bacterial endotoxin have been implicated in the aetiology of alcoholic liver disease. Using in vivo microscopic methods, we have shown that ethanol ingestion in mice causes a dose dependent increase in leucocyte adhesion and endothelial cell swelling in hepatic sinusoids. Activation of KC is elicited at low doses while depression occurs at high doses and with chronic exposure. The responses are exacerbated in the presence of endotoxaemia or sepsis and are not seen in endotoxin-resistant animals, implicating a role for endotoxin in the ethanol-induced inflammatory response. In addition, the responses are abolished with anti-TNF alpha suggesting that TNF alpha is a primary mediator of these events. Nitric oxide (NO) initially appears to play an important role in these events by stabilizing the TNF alpha-mediated hepatic microvascular inflammatory response to acute ethanol ingestion, thereby helping to protect the liver from ischaemia and leucocyte induced oxidative injury. Finally, an ongoing clinical study has confirmed a mild systemic endotoxaemia in patients hospitalized for alcoholic liver disease. All of these results support important roles for endotoxin, cytokines, nitric oxide and sinusoidal lining cells in the pathophysiology of liver injury resulting from ethanol alone or in combination with infection.

Digit replantation in infants and young children: determinants of survival.

Thirty-three children under 34 months of age with 41 digits amputated over a 15-year period were reviewed. There were 3 primary amputations, 6 composite grafts, and 32 replantations. Twenty-one variables were evaluated for their influence on 4-week digit survival. The overall survival rate of 32 replanted digits was 69 percent. Favorable uncontrollable variables were clean-cut injury and body weight greater than 11 kg. Favorable controllable variables included more than one vein repaired, bone shortening, interosseous bone fixation, and vein grafting of arteries or veins. Forty-one percent of children required a blood transfusion. Children with trauma to more than one digit were most likely to be transfused (p < 0.05). The combination of prompt digit reperfusion after successful arterial repair and at least one successful venous anastomosis resulted in a 95 percent digit survival rate, significantly higher than the 0 percent survival of digits lacking one or the other of these features.

Effects of cholinesterase inhibitors on the neuromuscular blocking action of suxamethonium.

Prolonged neuromuscular block occurs when suxamethonium is given after neostigmine or pyridostigmine; however, studies of edrophonium and suxamethonium have yielded conflicting results. We have studied, therefore, interactions between suxamethonium and all three anticholinesterases in rats anaesthetized with pentobarbitone. After recovery from an initial bolus of suxamethonium, saline, edrophonium, pyridostigmine or neostigmine was administered and a second dose of suxamethonium was then given. All three anticholinesterases prolonged the duration of neuromuscular block (90% suppression to 50% twitch recovery) to 127 (SEM 9)%, 127(10)% and 138 (11)% of baseline for edrophonium, pyridostigmine and neostigmine, respectively. Recovery index (25% to 75% twitch recovery) was increased also to 125 (9)%; 149 (10%) and 185 (15)% of baseline, respectively for the three drugs.

Visual and auditory cortical lesions following acquisition of an intensity discrimination in rats fail to disrupt cross-modal transfer.

The effect of visual or auditory decortication on cross-modal transfer of an intensity discrimination was examined in rats. Twenty animals were first trained under either visual-auditory (V-A) or auditory-visual (A-V) cross-modal transfer (CMT) in a shuttlebox using a shock avoidance pardigm. Prior to the second training session, five of the A-V animals received auditory ablations and five V-A animals received visual ablations. The other 10 animals served as controls and received sham operations. The results reveal that CMT occurred in both experimental groups following cortical ablations. It is possible that information regarding stimulus intensity was transferred from a cortical region used during the original training session to the cortex used in the second or retraining session, prior to surgery. Alternatively, it may be that some subcortical structure (e.g. the amygdala, superior colliculus, or reticular formation) may be involved in CMT of intensity.

Infant monitoring resulting in burns-tissue damage: literature review and case report.

Noninvasive infant monitoring occasionally results in burns and tissue damage. The medical literature now contains 14 isolated reports that were summarized for this review. All 14 victims were less than 24 months of age, and of these 14, two died by electrocution. Burns and tissue damage resulted from infant respiratory monitors (six), pulse oximeters (four), electrocardiographic monitors (two), an anal myoneural junction monitor (one), and a fetal scalp monitor (one). Infant extremities were injured most often (40%), and the trunk was burned somewhat less frequently (23%). Infants were burned in the hospital (57%) only slightly more often than at home (43%). Household burns involved only infant cardiorespiratory monitors. The most common mechanism of injury was the misapplication or improper connection of electrode lead wires (57%). A full one third of infants with burns required a reconstructive surgical procedure, usually a skin graft. Risk factors related to monitor-induced burns and tissue damage have been identified and presented. Injury prevention principles are also outlined.

Superior vena cava syndrome: etiology, diagnosis, and treatment.

Superior vena cava (SVC) syndrome is a critical condition in which an intrathoracic mass lesion compresses the SVC and promotes the development of head and upper body edema and cyanosis. SVC syndrome develops in 10% of patients with a right-sided malignant intrathoracic mass lesion. Diagnostic evaluation and emergency therapy are always necessary to assess and alleviate airway obstruction, cerebral venous hypertension and symptoms secondary to mediastinal compression. Radiation therapy and venous bypass of the obstructed SVC are both used successfully as early treatment. Although radiation therapy to the malignant process may provide initial decompression, a more sustained decrease in venous pressure occurs in patients who also undergo decompressive SVC surgical bypass. SVC bypass should be considered early in the course of patients with profound cerebral or laryngeal edema, patients with extensive thrombosis of the SVC, and in rare patients afflicted with severe venous hypertension and in whom a tissue diagnosis requires a mediastinal exploration.

Microvascular digit transposition following a two-digit amputation in an infant.

Multiple digit amputations in children demand special consideration to make subsequent hand function optimal. Replanted digits in children have a comparatively lower viability rate, but those that do survive usually go on to excellent function. In this case, an amputated thumb was severely mangled and not suitable for replantation. An amputated index finger was transposed to the thumb position. A six-month postoperative follow-up of the transposed digit confirmed satisfactory joint motion, restored sensibility, and unimpaired digit growth. The 11-month-old infant described is the youngest patient ever reported to have undergone a successful emergency microvascular digit transposition.