Hydroxyapatite-coating of pedicle screws improves resistance against pull-out force in the osteoporotic canine lumbar spine model: a pilot study.

BACKGROUND CONTEXT: In patients with spinal osteoporosis, the early achievement and maintenance of a biological bond between the pedicle screw and bone is important to avoid screw loosening complications. There are few reports of in vivo investigations involving biomechanical and histological evaluations in the osteoporotic spine. PURPOSE: To evaluate the effect of hydroxyapatite (HA)-coating on the pedicle screw in the osteoporotic lumbar spine and to investigate the relationship between resistance against the screw pull-out force and bone mineral density (BMD) of the vertebral body. STUDY DESIGN/SETTING: Mechanical and pathological investigations in the lumbar spine. METHODS: Two 24-month-old female beagle dogs were fed a calcium-free dog chow for 6 months after ovariectomy (OVX). BMD (in g/cm2) was measured by dual energy X-ray absorptiometry at pre-OVX and 6 months after OVX. Pedicle screws were placed from L1 to L6 at 6 months after OVX. Twenty-four pure titanium cortical screws (Synthes, #401-114) were used as pedicle screws (Ti-PS). Of these, 12 screws had HA-coating (HA-PS). The HA-PS screws were inserted into the right pedicles and the Ti-PS were inserted into the left pedicles. Ten days after this procedure, the lumbar spines were removed en bloc for screw pull-out testing and histological evaluation. RESULTS: The mean BMD value of the lumbar vertebrae 6 months after the OVX was 0.549+/-0.087 g/cm2, which was significantly less than the pre-OVX mean BMD of 0.603+/-0.092 g/cm2 (p < 0.001). The mean resistance against the pull-out force for the HA-PS was significantly greater at 165.6+/-26.5N than in the Ti-PS (103.1+/-30.2N, p < .001). The histological sections in the HA-PS clearly revealed new bone bonding with the apatite coating but only fibrous tissue bonding in the Ti-PS. CONCLUSIONS: The results of this study showed that the resistance to the pull-out force of HA-PS is 1.6 times that of Ti-PS. Furthermore, HA-PS has superior biological bonding to the surrounding bone, as early as 10 days after surgery in this osteoporotic spine model. Thus, in patients with osteoporosis, coating of the pedicle screw with HA may provide better stability and bonding between the pedicle screw and bone in the early postoperative period.     

Effect of tissue inhomogeneity on beta dose distribution of 32P

In a homogeneous medium of soft tissue the radiation dose distribution due to a nonuniformly distributed beta source can be calculated by convolution of the beta dose point kernel of the nuclide with the source distribution. A possible extension of the technique to the calculation of the dose distribution in heterogeneous media involving relatively simple geometric interfaces requires the knowledge of the resulting perturbation to the beta point kernels in individual media. We simulated a soft-tissue-bone planar interface by a polystyrene (PST)-aluminum junction and measured the change in beta dose from the dose value in homogeneous PST due to a point source of 32P using 7LiF thermoluminescent dosimeters. With the point source at the interface, the dose rates at 0-31, 125-156, and 283-314 mg/cm2 separations from the interface were increased by (12 +/- 3)%, (8 +/- 2)%, and (3 +/- 2)%, respectively, compared with homogeneous PST. With the point source at a PST-air planar interface to simulate a soft-tissue-air junction, the dose rates at 0-31, 139-170, and 283-314 mg/cm2 from the interface were decreased by (25 +/- 4)%, (11 +/- 7)%, and (5 +/- 2)%, respectively. The changes in dose rates for these two interfaces have also been measured with degraded spectra of 32P. Comparison of the experimental data with Monte Carlo calculation for a point source and the two-group method of calculation for a plane source is also presented.     

Alkaloidal components ofPanax ginseng

Over twelve alkaloids were delected in the roots ofPanax ginseng C.A. Meyer. Among them three alkaloids were isolated and were identified as N₉-formylharman, ethyl β-carboline-1-carboxylate and perlolyrine on the basis of spectroscopic studies.     

Cyclin E, p27 and mutant p53 do not predict the prognosis in AJCC stage II colorectal carcinomas.

BACKGROUND/AIMS: Carcinogenesis is characterized by the abnormal regulation of cell cycle. The abnormal expression of the regulators of cell cycle may be related to the prognosis. Since the clinical significance of the expression of the three proteins in colorectal carcinomas is still controversial, we evaluated the prognostic value of the expression of cyclin E, p27 and mutant p53 in stage II colorectal cancer. METHODS: The expression levels of cyclin E, p27 and mutant p53 proteins in 41 patients with stage II colorectal carcinomas were analyzed by immunohistochemistry. RESULTS: In the univariate analysis, the level of CEA at diagnosis was associated with disease relapse. In the multivariate analysis, the clinicopathological variables such as age, gender, site of primary tumor, tumor size, state of tumor differentiation and preoperative plasma CEA level were not associated with disease relapse. When Kaplan-Meier survival curves were constructed to determine the prognosis, cyclin E, p27 and mutant p53 expressions did not predict poor prognosis. CONCLUSIONS: Our results suggested that the expression of cyclin E, p27 and mutant p53 proteins did not predict the clinical outcome in the stage II colorectal carcinomas.     

Recombinant tissue-plasminogen activator (rt-PA) in acute myocardial infarction in the Chinese in Hong Kong.

Eighty-nine consecutive Chinese patients (69 males, 20 females) with acute myocardial infarction treated by 100 mg recombinant tissue-plasminogen activator (rt-PA) (7 intracoronarily, 82 intravenously) at 3.7 +/- 1.0 hours after onset, and intravenous heparin or dipyridamole therapy started at 3 hours, were studied prospectively. Their mean age was 59.6 +/- 10.6 years. Forty-six patients (51.7%) had anterior and 39 patients (43.8%) had inferior infarcts. Clinical evidence of reperfusion was seen in 63 patients (72.8%), while new complications included hypotension (5.6%), heart failure (6.7%), cardiac arrhythmias (76.4%), hematoma around vascular access sites (23.6%), melena (2.2%) and cerebral infarction (2.2%). Maximal changes in coagulation profiles were seen at 3 hours, including a decrease in fibrinogen (by 64.2%), an increase in FDP by 11.7 times and D-dimers by 4.4 times. Nine patients (10.1%) had recurrence of angina and 6 patients (6.9%) died due to pump failure (5) and reinfarction (1). Angiogram at 14 days confirmed TIMI (2 or 3) patency of infarct related arteries in 62/81 (76.5%) patients, with a mean global ejection fraction of 52.5 +/- 12.4%. Nearly all survivors could maintain class I-II functional status after discharge. The safety and promises of rt-PA for acute myocardial infarction in the Chinese were confirmed.

     

Excursion of the flexor digitorum profundus tendon: a kinematic study of the human and canine digits

The most common problem following primary flexor tendon repair is the failure of the tendon apparatus to glide, secondary to the formation of adhesions. Early motion following tendon repair has been shown to be effective in reducing adhesions between the tendon and the surrounding sheath. Therefore, it is important to determine the amount of flexor tendon excursion along the digit during joint motion. In this study, the excursion between the flexor digitorum profundus (FDP) tendon and the sheath was examined in both human and canine digits. Based on roentgenographic measurements and joint kinematic analysis, the motion of the bones, the FDP tendon, and the sheath were measured with respect to joint rotations. It was found that the canine flexor tendon apparatus behaved similarly to that of the human for the motions studied. The amount of tendon excursion was very small in regions distal to the joint in motion (approximately 0.1 mm/10 degrees of joint rotation). There was little displacement of the sheath (0.2-0.3 mm), except at the metacarpal joint region during metacarpophalangeal (MCP) joint motion and at the proximal interphalangeal (PIP) joint region during PIP joint motion. Tendon excursion relative to the tendon sheath was the largest in zone II during PIP joint rotation (1.7 mm/10 degrees of joint rotation). These results suggest that PIP joint motion may be most effective in reducing adhesions following tendon repair in zone II.     

Reproducibility of angiotensin converting enzyme inhibitor induced cough: A double-blind randomised study

1 The reproducibility of angiotensin converting enzyme inhibitor induced cough was examined in a double-blind cross over study in patients previously shown to have exhibited this side effect.

2 Ninety-seven patients who had experienced angiotensin converting enzyme inhibitor cough within the last 2 years were challenged with enalapril 20 mg daily for 4 weeks to establish eligibility. Eighty-eight of 97 (91%) patients experienced a repeat of their cough symptoms. Sixty-four patients entered the double-blind part of the study where they were treated with enalapril 20 mg and a renin inhibitor for up to 4 weeks in random order. These periods were separated by a minimum 4 week placebo wash out.

3 Of 59 evaluable patients who received enalapril a second time, 37 (62.7%) experienced cough again. Of 62 patients on the renin inhibitor 16 (25.8%) experienced cough, however as it was not equi-efficacious to enalapril no valid comparison could be made.

4 Angiotensin converting enzyme inhibitor cough is not reproducible within patients, as other factors are involved in the aetiology. Objective testing with blinded assessment together with symptom reporting, would give a more accurate measure of the incidence, and mechanism of this side effect.

     

The tumor promoters 12-O-tetradecanoylphorbol-13-acetate and okadaic acid differ in toxicity, mitogenic activity and induction of gene expression

Okadaic acid (OA) and 12-O-tetradecanoylphorbol-13-acetate (TPA)are both potent tumor promoters in a mouse skin carcinogenesisexperiment. OA was much more toxic than TPA for murine embryocell lines such as Swiss 3T3 cells or C3H10T? cells. TPA isa potent mitogen for 3T3 cells; in contrast OA was unable tostimulate DNA synthesis in these cells. TPA induces a familyof primary response genes, the TPA induced sequence (TIS) genes,in a wide variety of cells. Although OA induced modest levelsof TIS mRNA expression, the time course of the induction ofTIS1 and TIS8 mRNA was delayed when compared to induction byTPA or peptide mitogeas such as fibroblast growth factor (FGF).In addition TPA-mediated down-regulation of protein kinase Cattenuated TIS gene induction by OA, but not by FGF.     

Treatment planning for asymmetric jaws on a commercial TP system.

In this work, the accuracy of the asymmetric jaws planning feature in a commercial treatment planning (TP) system is assessed. In the latest version of this software, the off-axis beam quality variation is handled by a function g(d,r), which is derived from measured horizontal beam profiles at four different depths. The calculated and measured isodoses for a 6-MV linear accelerator with asymmetric jaws agree to +/- 0.5% along the central axis and to within 2 mm at the beam edge. Formulas for treatment time calculations using the output data reported by the computer program are described, as well as formulas for manual calculations based on pregenerated data tables. Doses calculated based on these formulas are compared to measurement and the accuracy is +/- 1% and +/- 2% for the computer and manual calculations, respectively. It is concluded that this version of the treatment planning system as well as the treatment time calculation formulas can be used adequately for asymmetric jaw computerized and manual treatment planning.     

Purification of the human blood platelet thromboxane A2/prostaglandin H2 receptor protein.

The human platelet thromboxane A2/prostaglandin H2 receptor has been purified 6100-fold to apparent homogeneity by a three-step chromatographic procedure with an overall yield of 6%. A 6-fold purification of the receptor was first achieved by chromatography of 3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate (CHAPS)-solubilized membrane proteins from human platelets on a diethylaminoethyl (DEAE)-Sepharose column. The DEAE eluate fractions containing receptor activity were then applied to a newly developed affinity column using the cyclohexyl derivative of SQ30,741 (SQ31,491) as the immobilized ligand. Elution of the receptor from the affinity column with BM13.177 yielded a further purification of 1700-fold. An additional 4-fold receptor purification from the affinity column eluate was achieved by HPLC using GPC 500 and GPC 100 columns connected in tandem. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining of the HPLC eluate containing purified receptor revealed a single, distinct band with a molecular weight of 55,000. The receptor binding activity was detected with [3H]SQ29,548 using a newly developed binding assay which involved immobilization of the receptor on polyethyleneimine-treated glass fiber filters. The binding of [3H]SQ29,548 to the purified receptor was time dependent, saturable, reversible and highly specific. Unlabeled SQ29,548, BM13.505, and U46619 (but not thromboxane B2 or 6-keto prostaglandin F1 alpha) competed for [3H]SQ29,548 binding to the purified receptor in a concentration-dependent manner. Scatchard analysis of [3H]SQ29,548 binding to the purified receptor revealed the presence of a single class of high-affinity binding sites, with a Kd of 4 nM and a Bmax of 17 nmol/mg protein.