Growth factors regulate expression of osteoblast-associated genes.

BACKGROUND: The goal of periodontal regenerative therapies is to reconstruct periodontal tissues such as bone, cementum, and periodontal ligament cells (PDL). The need to establish predictable treatment modalities is important for reconstruction of these tissues. The aim of this study was to determine the effects of a low molecular extract of bovine bone protein (BP) containing bone morphogenetic proteins (BMPs) 2, 3, 4, 6, 7, 12, and 13, alone or in combination with platelet-derived growth factor (PDGF) and/or insulin-like growth factor (IGF) on osteoblast differentiation in vitro. METHODS: BP, mixed with a collagen matrix, was added to a poly (DL-lactide-co-glycolide) polymer (PLG) and placed at orthotopic sites in the skullcaps of Sprague-Dawleys rats. At day 28, rats were sacrificed for histological analysis. All sites treated with the polymer/BP produced bone while control sites (without BP) showed no bone formation. Having established the biological activity of BP, in vitro studies were initiated using MC3T3-E1 cells, a mouse osteoprogenitor cell line. The ability of BP and other growth factors to alter cell proliferation was determined by Coulter counter, and differentiation was determined by Northern analysis for specific genes. RESULTS: When compared with cells treated with 2% serum alone, PDGF enhanced cell numbers at 10 and 20 ng/ml; IGF produced no significant effect at these doses; and BP at 10 and 20 microg/ml decreased cell proliferation. Northern analysis revealed that PDGF blocked gene expression of osteopontin (OPN) and osteocalcin (OCN), while BP and IGF promoted gene expression of bone sialoprotein (BSP) and OPN. The combination of BP and IGF enhanced expression of OPN beyond that of either BP or IGF alone. PDGF was able to block the effects of IGF on gene expression, but not those of BP. CONCLUSIONS: These results indicate that BP, PDGF, and IGF influence cell activity differently, and thus raise the possibility that combining factors may enhance the biological activity of cells.

Therapeutic options for severe, refractory status asthmaticus: inhalational anaesthetic agents, extracorporeal membrane oxygenation and helium/oxygen ventilation.

Despite improvements in supportive care, the mortality and morbidity of asthma remain constant. The risks and incidence of morbidity related to barotrauma remain high in patients that require mechanical ventilation. The authors present three alternative strategies including the inhalation of anaesthetic agents, helium/ oxygen ventilation, and extracorporeal membrane oxygenation which may be beneficial when "conventional therapies' fail in the intubated patient with status asthmaticus.

Effects of cytomegalovirus infection on growth factor production in endothelial cells and fibroblasts.

To determine whether cytomegalovirus (CMV) infection alters growth factor production from endothelial cells (EC) or fibroblasts, we infected human umbilical vein EC with CMV VHL/E, a strain of CMV with affinity for human EC, and we infected human foreskin fibroblasts with CMV AD169. CMV caused cytopathic effect and positive CMV staining by immunofluorescence within 5 d, effects not seen in cells infected with UV-irradiated CMV or in uninfected (control) cells. The supernatants from the EC were assayed for platelet-derived growth factor (PDGF)-like protein using a radioreceptor inhibition assay, and EC and fibroblasts were assayed for basic fibroblast growth factor (bFGF) by Western blot analysis. There were no significant differences in PDGF production between groups of EC: CMV-infected EC, 13.5 +/- 2.6; UV-irradiated infected EC, 12.1 +/- 3.6; control EC, 12.9 +/- 1.7 fmol/10(6) EC (mean +/- SD, n = 10, p = NS). There were also no significant differences in bFGF production between CMV-infected EC, UV-irradiated infected EC, and control EC as evidenced by similar intensity of migration of bFGF as a single band at approximately 18 kD (n = 5). In contrast, CMV infection of fibroblasts induced a shift in production of bFGF to higher molecular weight forms migrating at 24 and 26 kD molecular mass. alpha-Interferon failed to alter bFGF production. We conclude that CMV VHL/E infection of EC does not directly alter PDGF or bFGF production from EC. However, CMV infection of cultured human fibroblasts qualitatively alters bFGF by inducing a shift to higher molecular weight forms.

Pancuronium infusion for neuromuscular block in children in the pediatric intensive care unit.

When neuromuscular blockade becomes necessary in the intensive care unit, there are several options available in regard to both the drug and the mode of delivery (continuous versus intermittent administration). Despite extensive experience with intermediate acting drugs such as atracurium or vecuronium, these muscle relaxants are costly and may account for a significant portion of the pharmacy charges. We undertook an open label study to evaluate the efficacy and dosing requirements for a less costly drug, pancuronium. The study group included 25 patients ranging in age from 3 mo to 17 yr and in weight from 3.2 to 68 kg. If the patient had not previously received neuromuscular blocking agents (NMBAs), pancuronium was administered as a bolus dose of 0.1 mg/kg followed by a continuous infusion of 0.05 mg.kg-1.h-1. A nerve stimulator was applied to either the ulnar or peroneal nerve and a standard train-of-four (TOF) was monitored every 2 h. In patients that had previously received other NMBAs, no bolus dose of pancuronium was administered and the infusion was started at 0.05 mg.kg-1.h-1. The pancuronium infusion was increased or decreased by increments of 0.01 mg.kg-1.h-1 to maintain one to two twitches of the TOF. In patients that required an increase in the infusion rate, an additional bolus dose equivalent to the current hourly rate was administered and then followed by the increase in the infusion rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive monitoring of end-tidal carbon dioxide tension via nasal cannulas in spontaneously breathing children with profound hypocarbia.

OBJECTIVE: To determine the correlation between end-tidal CO2 and PaCO2 measured via nasal cannulas in spontaneously breathing children with profound hypocarbia (PaCO2 < 30 torr [< 4.0 kPa]). DESIGN: Prospective evaluation. SETTING: Pediatric intensive care unit (ICU) in a tertiary care referral center. INTERVENTIONS: None. PATIENTS: Patients admitted to the ICU with a diagnosis of diabetic ketoacidosis in whom invasive arterial access was deemed necessary for clinical care. The patients were spontaneously breathing, without intubation. The study included nine patients, with an average age of 9.9 yrs (range 4 to 17) and weight of 38.7 kg (range 17 to 68). MEASUREMENTS AND MAIN RESULTS: End-tidal CO2 was sampled from nasal cannulas by a sidestream aspirator and estimated by infrared spectroscopy. The correlation between arterial and end-tidal CO2 was compared using linear regression analysis. A total of 65 arterial blood gases were obtained from the nine patients. The PaCO2 was < or = 30 torr (< or = 4.0 kPa) in 38 of the samples. The PaCO2 to end-tidal CO2 gradient was < or = 4 torr (< or = 0.5 kPa) in 64 of 65 samples and 4.8 torr (0.6 kPa) in one sample. Linear regression analysis of arterial vs. end-tidal CO2 yielded a slope of 0.99, an r2 value of .97, and a p value of .0001. CONCLUSIONS: End-tidal CO2 measurement by infrared spectroscopy provides an accurate estimation of PaCO2, even during episodes of severe hypocarbia. Its use may limit the need for invasive monitoring and/or repeated arterial blood gas analyses.

Noninvasive monitoring of end-tidal CO2 via nasal cannulas in spontaneously breathing children during the perioperative period.

OBJECTIVE: To determine the correlation between end-tidal CO2 and PaCO2 values measured via nasal cannulas in spontaneously breathing children during the perioperative period. DESIGN: Prospective evaluation. SETTING: Pediatric intensive/intermediate care unit in a tertiary care referral center. PATIENTS: Thirty postoperative surgical and trauma patients aged < or = 18 yrs (average age 7.8 yrs [range 6 months to 16 yrs] and average weight 28.3 kg (range 8.5 to 69). MEASUREMENTS AND MAIN RESULTS: Spontaneously breathing, nonintubated patients with an arterial cannula in place were selected for study. End-tidal CO2 was sampled from nasal cannulas by a sidestream aspirator and was estimated by infrared spectroscopy. The difference between PaCO2 and end-tidal CO2 was compared using linear regression analysis. A total of 55 blood gas measurements were obtained on the 30 patients. The PaCO2 to end-tidal CO2 gradient was < or = 4 torr in 54 of the 55 samples. The mean PaCO2 was 39.5 +/- 3.3 torr (5.27 +/- 0.44 kPa) with a mean end-tidal CO2 value of 39.7 +/- 3.8 torr (5.29 +/- 0.51 kPa). Linear regression analysis of arterial vs. end-tidal CO2 yielded a slope of 0.992 and p = .0001. CONCLUSIONS: End-tidal CO2 measurement by infrared spectroscopy provided an accurate estimation of PaCO2 in this patient population. Its use may limit the need for invasive monitoring and/or repeated arterial blood gas analysis.

Hemodynamic effects of dobutamine in an intact animal model.

BACKGROUND AND METHODS: Actions of dobutamine at the beta 1, beta 2, and alpha 1 adrenoreceptors were studied in anesthetized dogs. Six animals received dobutamine (at infusion rates of 0 to 160 micrograms/kg/min) with and without beta-adrenergic receptor blockade. Five animals received phenylephrine (0 to 16 micrograms/kg/min), with and without concurrent dobutamine (20 micrograms/kg/min); this procedure was repeated in five animals after beta-blockade. RESULTS: Dobutamine (10 to 160 micrograms/kg/min) increased heart rate (HR), cardiac output, and left ventricular change in pressure over time, and decreased systemic vascular resistance. beta-blockade prevented only dobutamine-induced changes in HR. Mean arterial pressure (MAP), unaffected by dobutamine alone, decreased with concurrent beta-blockade. Phenylephrine (1 to 16 micrograms/kg/min)-induced increases in MAP were unaffected by dobutamine; with beta-blockade, phenylephrine reduced MAP. Dobutamine prevented a phenylephrine-induced increase in systemic vascular resistance, an effect eliminated by beta-adrenergic receptor blockade. CONCLUSIONS: Dobutamine appeared to be an agonist at the beta 1- and beta 2-adrenoreceptors and at the myocardial alpha-adrenoreceptor. Dobutamine appeared to be an alpha-adrenergic receptor antagonist in the peripheral vasculature.

Efficacy of dopamine and norepinephrine for treatment of hemodynamic compromise in amitriptyline intoxication.

BACKGROUND AND METHODS: Dopamine and norepinephrine were evaluated for treatment of hemodynamic compromise in amitriptyline intoxication. Fifteen anesthetized dogs underwent hemodynamic monitoring and amitriptyline intoxication, and received three infusion rates of dopamine (5, 15, and 30 micrograms/kg.min) and three infusion rates of norepinephrine (0.25, 0.5, and 1.0 micrograms/kg.min), sequentially, with hemodynamic measurements at each dose. Data were analyzed using repeated-measures analysis of variance; p less than .05 was considered significant. RESULTS: Amitriptyline intoxication lowered cardiac output, peak left ventricular dP/dt, and mean arterial pressure (MAP). All doses of norepinephrine and the two higher doses of dopamine increased cardiac output, MAP, and peak left ventricular dP/dt during the intoxicated state. Both agents restored all variables to preintoxication values. Values obtained at the highest doses of the two drugs were not different for any variable. CONCLUSION: Dopamine and norepinephrine each appeared effective in reversing amitriptyline-induced hemodynamic alterations.

Quantitation of intracardiac shunts by cine-CT.

Quantitation of intracardiac shunts is important in the evaluation of congenital heart disease and ventricular septal defects postmyocardial infarction. Shunt detection and quantitation is currently performed by either oximetry or radionuclide angiography. Oximetry is an invasive technique and radionuclide angiography, although noninvasive, does not have sufficient spatial resolution to provide detailed anatomic information. The present study evaluated a new technique for quantitating right-to-left shunts by analysis of indicator dilution curves acquired noninvasively using cine-CT. This technique was evaluated in a phantom and in postoperative dogs with a surgically created variable shunt. The phantom model demonstrated the accuracy and reproducibility of the curve analysis algorithm, and the canine model permitted the comparison of oximetry with cine-CT for shunt quantitation. Cine-CT accurately estimated right-to-left shunt fraction when compared with oximetry (r = 0.91) and is more sensitive than oximetry in detecting small shunts. The results of this study suggest that contrast enhanced cine-CT provides a precise noninvasive technique for measuring shunt lesions in congenital and acquired heart diseases.

Verapamil prevents the development of alcoholic dysfunction in hamster myocardium.

Ethanol causes depression of cardiac function. A new model in hamsters was developed for studying ethanol-induced myocardial dysfunction and the effects of verapamil in preventing the functional and metabolic derangements caused by ethanol ingestion were evaluated. Ethanol was added to the drinking water of hamsters in increasing amounts, reaching 50% from 5 weeks on. A control group received plain water only. A third group had verapamil (1.75 mg/cc) added to the ethanol-water mixture to evaluate its potential protective effect. After 5, 7 and 12 weeks, the animals were killed and the hearts perfused using a Langendorff heart preparation. Pressures were recorded and metabolic analysis was performed by the freeze-clamp technique. Compared with control hearts, the hearts from hamsters ingesting ethanol showed significant depression of developed pressure and maximal rate of rise in pressure. There was also significant depression of high energy phosphates and adenosine. The animals drinking the ethanol-verapamil mixture had preservation of left ventricular performance and high energy phosphates, with measurements indistinguishable from those of the control group. In summary, verapamil prevented the development of myocardial depression and preserved normal energy metabolism in hearts of hamsters drinking 50% ethanol.

Cine-computed tomography of Ebstein anomaly.

A case of Ebstein anomaly is reported, and the diagnostic potential of cine-CT in assessing the magnitude of the anatomic changes and the presence of right to left intracardiac shunting is evaluated.

Right-sided cardiac transplantation: importance of functional valves.

An original surgical procedure had been developed entailing the implantation of a right-sided heterotrophic cardiac graft in 14 dogs. The benchwork preparation included creation of both atrial and ventricular septal defects which allowed transplantation with the avoidance of extracorporeal circulation and the utilization of all transplanted myocardium and parts. The structure and function of this graft were sequentially evaluated using rapid cine-computed tomograms which permitted assessment of forward graft flow, ventricular wall contraction, and diastolic thickness for both the native and grafted hearts. These parameters were followed during the early (E) (less than 3 days), intermediate (I) (4-21 days), and late (L) (greater than 21 days) postoperative periods. Forward flow (E: 3.0, I: 1.5, L: 2.6) through the transplant was maintained by the competence of the implanted valves despite a progressive decrease in the contraction (E: 3.0, I: 1.3, L: 1.0) and associated decrease in the wall thickness (E: 3.0, I: 2.6, L: 2.4). These findings were consistent with severe cardiac graft rejection without immunosuppression. In summary, long-term structural and functional forward flow of this configurated right-sided transplantation had been maintained by the competent valves on both sides of the graft despite severe rejection without immunosuppression as documented by rapid cine-computed tomograms.

Cine-computed tomography of arrhythmogenic right ventricular dysplasia.

The CT diagnostic features of arrhythmogenic right ventricular dysplasia (Uhl anomaly) are described in a 72-year-old man. High speed cine-CT was performed using millisecond exposures and multilevel scanning. Ventricular morphology and function were evaluated, and findings were compared with two-dimensional echocardiography and equilibrium gated blood pool imaging. Cine-CT showed a dilated hypokinetic right ventricle with a markedly thin anterior wall and normal left sided chambers. The clinical aspects of Uhl anomaly are reviewed.

Measurement of cardiac output by cine computed tomography.

High-speed computed transmission tomography (cine CT) is a new noninvasive technique that may be useful for the rapid, accurate quantitation of cardiac function. The capability of cine CT to assess cardiac output was examined 10 mongrel dogs as an initial step in validating this method. After the dogs were anesthetized, femoral arterial pressure and pulmonary artery thermodilution catheters were inserted. After intravenous injection of a bolus of contrast medium, cine CT scans were performed in the flow mode, in which 50-ms scans were triggered electrocardiographically at end-diastole at 8 levels during sequential cardiac cycles. Scans and thermodilution measurements of cardiac output were obtained at rest and during altered hemodynamic states induced by separate infusions of dobutamine and phenylephrine. Time-density analysis was performed over the left ventricular cavity and curves were fitted to the CT flow data by gamma-variate analysis. Using the Stewart-Hamilton equation established for indicator dilution techniques, the cardiac output was calculated. The results established a direct linear correlation (r = 0.92) between cine CT cardiac output and thermodilution cardiac output over a wide range of cardiac outputs (1.5 to 6.3 liters/min). This study demonstrates that cine CT can provide a reliable estimate of cardiac output noninvasively using contrast medium as an indicator in dogs.

Computed axial tomography of the heart.

CT scanning provides useful cardiac imaging but has not become a routine clinical tool for heart disease due to long exposure times (2-5 seconds) and the limitation of single slice acquisition. A revolutionary high speed (Cine) CT electron beam scanner was designed at UCSF, with multilevel millisecond scanning speed at rates of 17 scans per second. Table tilt and swivel permits direct imaging in various planes including the half axis view. Images can be analysed as closed loop movies, and quantitation of wall thickening, wall mass and ejection fractions are being validated. High resolution imaging without the need for gated acquisition is a significant advantage over nuclear medicine and magnetic resonance imaging, and physiology can be studied with exercise of other interventions. Fast CT can measure vessel blood flow and has great potential for estimating myocardial perfusion using indicator dilution theory and small peripheral intravenous injection of contrast medium. Cine CT could become the noninvasive modality of choice in cardiovascular diagnosis - the scanner has universal application for all organ systems.

Blockade of autocrine stimulation in simian sarcoma virus-transformed cells reverses down-regulation of platelet-derived growth factor receptors.

The viral (v)-sis oncogene encodes a protein (p28sis) that is structurally homologous to platelet-derived growth factor (PDGF). We have shown that simian sarcoma virus (SSV)-transformed cells containing the v-sis oncogene release a Mr 20,000 substance that is recognized by antisera to synthetic peptide sequences contained in p28sis. Medium conditioned by SSV-transformed cells competes with 125I-labeled PDGF for specific PDGF receptor sites, initiates DNA synthesis, and stimulates tyrosine phosphorylation of the PDGF receptor when added to normal cells. When normal cells are co-cultured with SSV-transformed cells, the PDGF receptors of the normal cells are down-regulated by factors released from the transformed cells. Thus, SSV-transformed cells release material that is functionally similar to PDGF. We have used anti-phosphotyrosine antibodies to purify PDGF receptors and to detect PDGF-stimulated receptors in normal cells. SSV-transformed cells have no PDGF receptors detectable by these antibodies or by 125I-labeled PDGF binding studies. However, when SSV-transformed cells are exposed to suramin, a compound that blocks binding of PDGF to its receptors, the receptors reappear on the cell surface and within 8 hr are present at the same levels as in control cells. These "new" receptor sites can be phosphorylated in response to PDGF. Thus, the absence of PDGF receptors in SSV-transformed cells is due to down-regulation of the receptors by an autocrine mechanism that can be blocked by suramin.

Effects of nonsurgical periodontal therapy on periodontitis in humans. A review.

Root planing is an effective method of treating both moderate and severe periodontitis. Predictable and significant improvement in bleeding scores, probing pocket depths and probing attachment levels have been demonstrated by a number of different research groups. Significant positive changes in the subgingival microflora are induced. These improvements can be sustained for longer periods of time if adequate supragingival plaque control is achieved. It is important to realize that the research to date excludes the effects of therapy on furcation pockets. Results of conservative therapy in this critical area remain to be studied.