Free volume and mechanical properties of Palacos R bone cement

The free volume and the mechanical properties of Palacos R bone cement were determined from positron annihilation lifetime spectroscopy (PALS) and from dynamic mechanical thermal analysis (DMA) in the temperature ranges 24-220 degrees C and 30-120 degrees C, respectively. The heating of bone cement caused an appreciable reduction of the free volume, measured as a decrease in the ortho-positronium lifetime tau(3) from 2.04 to 1.91 ns, as well as a clear increase in the storage modulus from 2.3 to 3.0 GPa. The changes in free volume and storage modulus after the heat treatment were interpreted as an effect of elimination of residual monomer from the bone cement. The free volume of the bulk-polymerized phase of bone cement was estimated from a simple difference method, suggesting that the residual monomer was eliminated from the bone cement between 60 and 90 degrees C, thus implying a glass transition temperature of only 60 degrees C for the bulk-polymerized phase. The spherical free volume cavity size estimated from the ortho-positronium lifetime V(tau(3)), and the storage modulus E'(storage) from DMA measurements were found to correlate by a linear relationship throughout the studied temperature range, and the correlation appeared to be independent of the presence of residual monomer.

The effects of masseter muscle pain on biting performance

The present study applied a standardized test food of known hardness to evaluate the biting performance of 20 female patients who had pain mainly in the masseter muscle during palpation. Another 20 women of a similar age group who were pain-free during examination served as controls. Electromyograms (EMG) of the masseter and sternocleidomastoid (SCM) muscles and the jaw position were recorded and measured when the subjects were biting through two types of test foods with known hardness (hard type, 20 kg hardness and extra-hard type, 60 kg hardness). Pressure-pain-threshold (PPT) values of both the patients and the normal subjects were obtained with an algometer. It was found that the PPT of the patients with pain was significantly lower and that the extra-hard food took more masseter muscle activity and more working side jaw movement in both the pain and the normal groups. During both hard and extra-hard food biting, a significantly longer duration of masseter muscle activity was found in pain patients while the total muscle activity was not significantly stronger. Strong correlation existed between SCM and masseter muscle activity during both hard and extra-hard food biting in the patient group, while such correlation was very weak in the normal group. In conclusion, painful masseter muscles required longer masseter and SCM muscle contraction time for breaking through a hard food of 20 kg and more, and co-activation of SCM and masseter muscles existed and was more evident when the food was harder or the pain was more severe.

Strenuous, acute exercise affects reciprocal modulation of platelet and polymorphonuclear leukocyte activities under shear flow in men

Vigorous exercise transiently increases the risk of primary cardiac arrest. The reciprocal modulation of platelet and polymorphonuclear leukocyte (PMN) activities is important in the pathogenesis of thrombosis. This study investigates how strenuous, acute exercise affects platelet-PMN reciprocal modulation by closely examining 18 sedentary men who exercised strenuously on a bicycle ergometer. Shear-induced platelet activation, PMN interaction with surface-adherent platelets under shear flow, and PMN-dependent inhibition of platelet activation were measured both before and immediately after exercise. Analytical results can be summarized as follows: (i) shear-induced platelet adhesion on fibronectin-coated surface as well as ADP-induced release of platelet soluble P-selectin release and elevation of [Ca2+]i significantly increases after strenuous exercise; (ii) strenuous exercise is associated with higher velocity and percentage of rolling PMNs and lower numbers of PMNs remaining bound to surface-adherent platelets under shear flow than at rest; (iii) PMN-dependent inhibition of platelet [Ca2+]i elevation and soluble P-selectin release after strenuous exercise is much greater than that at rest; and (iv) strenuous exercise increases PMN-derived nitric oxide metabolite level and reduces oxidized low-density lipoprotein-promoted interaction between platelets and PMNs. Therefore, we conclude that platelet activity may be sensitized by strenuous exercise. However, strenuous exercise can also simultaneously enhance the antiplatelet effect of PMNs. The finding provides a new insight into the negative feedback of PMNs against exercise-evoked platelet-related thrombotic risk.

Factors influencing the compressive strength of an injectable calcium sulfate-hydroxyapatite cement

A biphasic injectable bone substitute, suitable for filling bone defects, that sets in the body, based on calcium sulfate and hydroxyapatite (HA), is presented. For applications in bone defects the compressive strength is important to assure support of the defect site during loading when the patient is weight bearing. To control the strength, the influence of four different factors; the liquid-to-powder (L/P) ratio, the HA particle morphology, the HA content and the amount of accelerator, were investigated. alpha-Calcium sulfate hemihydrate (CSH) and four different HA powders (three sintered and one spray-dried) were used. All differed in size and morphology. CSH and each HA powder were mixed together with distilled water to form the bone substitute. An accelerator, in form of calcium sulfate dihydrate, was added to the powder phase to obtain an adequate setting time. Cylindrical specimens were compression tested. A lower L/P-ratio gave stronger cement, but was more difficult to inject. The shape and the morphology of the HA particles influenced the strength, and reducing the amount of HA increased the strength. The amount of accelerator (calcium sulfate dihydrate) had no influence.

Breastfeeding does not pose any additional risk of immunoprophylaxis failure on infants of HBV carrier mothers

Whether babies born to hepatitis B (HB) carrier mothers with HB immunoprophylaxis at birth can be breastfed safely is controversial. A total of 230 such babies were followed up for one year to assess the influence of feeding method on the efficacy of HB immunoprophylaxis. The positive rates of anti-HBs at different ages are not statistically different between the breastfed group and the bottle-fed group. At 1 year, the rate was 80.9% in the breastfed group and 73.2% in the bottle-fed group in infants with HB vaccine alone, and 90.9% in the breastfed group and 90.3% in the bottle-fed group in infants with HBIG plus HB vaccine. There were no significant differences in the incidence of immunoprophylaxis failure between breastfed and bottle-fed babies. The results indicated that breastfeeding does not have a negative influence on the response of anti-HBs and on the failure rates of immunoprophylaxis in the infants born to HB carrier mothers.

Should the cement mantle around the femoral component be thick or thin?

We have compared the survival and radiological outcome at ten years after total hip replacement using two techniques for preparing the femoral canal. The same prosthesis was used throughout and all operations were performed by the same surgical team. In technique 1 the canal was over-reamed by 2 mm and in technique 2 it was reamed to the same size as the prosthesis. Technique 1 was performed on 92 patients and technique 2 on 97 patients. The survival at ten years was 97.2% (90.6 to 99.2) for technique 1 and 98.8% (92.9 to 99.8) for technique 2. Vertical migration was greater in technique 1 (1.8 mm versus 1.0 mm at five years; p = 0.36). There were significantly more lytic lesions and radiolucent lines at five years (p = 0.0061) with technique 1. We conclude that technique 2 is not worse and may produce better long-term results than current teaching suggests.

Loss of cyclin D1 and p16 expression correlates with local recurrence in nasopharyngeal carcinoma following radiotherapy

BACKGROUND

The cyclin D1/p16/Rb pathway plays a critical role in tumorigenesis and each component of this pathway may be affected in various malignancies. The purpose of this study was to investigate the expression and prognostic significance of these proteins in nasopharyngeal carcinoma (NPC).

PATIENTS AND METHODS

Sixty-five patients undergoing radiotherapy for NPC were analyzed. The expression of cyclin D1, p16 and pRb was evaluated with immunohistochemical analysis of archived pretreatment tumor materials and expression of these proteins was correlated with clinicopathological parameters.

RESULTS

Positive expression of cyclin D1 was observed in 43 of 65 NPCs (66%). p16 and pRb inactivation was identified in 42 of 65 (65%) and four of 65 (6%) tumors, respectively. All but seven tumors (58 of 65, 89%) contained at least one alternation in the cyclin D1/p16/Rb pathway. Loss of cyclin D1 as well as p16 was closely related to local recurrence after radiotherapy for NPC (P = 0.015 and 0.047). No association between pRb expression and clinicopathological outcome was apparent.

CONCLUSIONS

The study's results suggest that the cyclin D1/p16/Rb pathway plays an important role in NPC tumorigenesis. We also find that cyclin D1 and p16 protein levels in NPC may be of use clinically as a predictor of local tumor control.

Fabrication of conventional complete dentures for a left segmental mandibulectomy patient: a clinical report

Without preprosthetic reconstructive surgery, denture fabrication for mandibulectomy patients becomes extremely difficult. Implant-assisted overdentures may improve denture retention and stability, but some patients cannot afford this treatment. For the segmental mandibulectomy patient described in this report, properly fabricated conventional complete dentures provided comfort and sufficient function.

Early genes responsive to abscisic acid during heterophyllous induction in Marsilea quadrifolia

The aquatic fern Marsilea quadrifolia produces different types of leaves in response to changes in natural environment and culture conditions. When the conditions are in favor of producing the submerged-type leaves, exogenous application of the plant hormone abscisic acid (ABA) induces the formation of aerial-type leaves. Tissues responsive to ABA were localized to the shoot apical meristem and the associated organ primordia. From these tissues, at least two tiers of ABA-regulated early genes were identified, including seven primary genes and seventeen secondary genes. These genes, designated ABRH for ABA-responsive heterophylly, showed diverse expression patterns during the course of heterophyllous induction. Changes in the transcript level of ABRH genes started early, within 0.5-1.0 h after the addition of ABA to the culture medium. Some changes were transient while the others were persistent. The ABRHs contain extensive sequence homology to known genes, including those encoding transcription factors, protein kinases, membrane transporters, metabolic enzymes, structural proteins and those encoded by the chloroplast genome. Identification of these ABRHs is a first step toward the understanding of the regulation mechanisms of heterophylly, and the results suggest the involvement of novel metabolic and regulatory pathways in ABA-controlled morphogenesis.

Matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 gene expressions and their differential regulation by proinflammatory cytokines and prostaglandin in nasal polyp fibroblasts

Chronic inflammation of the paranasal sinus leads to nasal polyp (NP) formation. In this study, we investigated the effect of stimulation of the proinflammatory cytokines interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) and prostaglandin (PG) E2 on the production of messenger RNA (mRNA) of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-I (TIMP-1) in nasal polyp fibroblasts (NPFs) and nasal mucosa fibroblasts (NFs). The mRNAs of IL-1alpha, TNF-alpha, MMP-1, and TIMP-1 in 40 surgical specimens of NPs were studied by in situ hybridization to corroborate the in vitro findings. The results indicated a significant amount of constitutive MMP-1 mRNA in NPFs and cytokine-induced MMP-1 steady-state mRNAs in NFs. The effect of stimulation of cytokines on TIMP-1 mRNA synthesis was unremarkable in NPFs and NFs. Exogenous PGE2 enhanced cytokine-stimulated MMP-1 mRNA synthesis in NPFs. In situ hybridization revealed that cells expressing MMP-1 and TIMP-1 mRNAs (primarily plasma cells, fibroblasts, and endothelial cells) gathered around areas with loose stroma, suggestive of rapid extracellular matrix degradation. These data suggest that the pathogenesis of nasal polyposis could be related to production of MMP-1 and consequent promotion of matrix collagenolysis.

Gemfibrozil is a potent inhibitor of human cytochrome P450 2C9

The in vitro inhibitory effects of gemfibrozil on cytochrome P450 (CYP) 1A2 (phenacetin O-deethylation), CYP2A6 (coumarin 7-hydroxylation), CYP2C9 (tolbutamide hydroxylation), CYP2C19 (S-mephenytoin 4'-hydroxylation), CYP2D6 (dextromethorphan O-deethylation), CYP2E1 (chlorzoxazone 6-hydroxylation), and CYP3A4 (midazolam 1'-hydroxylation) activities were examined using pooled human liver microsomes. The in vivo drug interactions of gemfibrozil were predicted in vitro using the [I]/([I] + K(i)) values. Gemfibrozil strongly and competitively inhibited CYP2C9 activity, with a K(i) (IC(50)) value of 5.8 (9.6) microM. In addition, gemfibrozil exhibited somewhat smaller inhibitory effects on CYP2C19 and CYP1A2 activities, with K(i) (IC(50)) values of 24 (47) microM and 82 (136) microM, respectively. With concentrations up to 250 microM, gemfibrozil showed no appreciable effect on CYP2A6, CYP2D6, CYP2E1, and CYP3A4 activities. Based on [I]/([I] + K(i)) values calculated using peak total (or unbound) plasma concentration of gemfibrozil, 96% (56%), 86% (24%), and 64% (8%) inhibition of the clearance of CYP2C9, CYP2C19, and CYP1A2 substrates could be expected, respectively. In conclusion, gemfibrozil inhibits the activity of CYP2C9 at clinically relevant concentrations, and this is the likely mechanism by which gemfibrozil interacts with CYP2C9 substrate drugs, such as warfarin and glyburide. Gemfibrozil may also impair clearance of CYP2C19 and CYP1A2 substrates, but inhibition of other CYP isoforms is unlikely.

Intramedullary spinal cryptococcoma: a case report

Intramedullary spinal cryptococcosis is very rare. We describe a case of intramedullary spinal cryptococcoma at the T12 level in a 60-year-old man who presented with a 3-month history of progressive bilateral lower limb weakness and no obvious immunocompromise. Magnetic resonance (MR) imaging revealed a 1.2 cm diameter mass within the spinal cord at T12 with intermediate signal intensity on T1-weighted images, a slight degree of homogeneous low signal intensity on T2-weighted images, and intense enhancement after infusion of gadopentetate dimeglumine. These findings led to a preoperative diagnosis of intramedullary tumor. After 2 months of postoperative antifungal treatment, the patient's clinical condition had markedly improved. Cryptococcoma should be considered when an enhancing lesion of the spinal cord is found on MR imaging, even in apparently immunocompetent patients. A careful lumbar puncture for cerebrospinal fluid analysis to diagnose cryptococcosis of the central nervous system should be made promptly, as early treatment is associated with a good prognosis.

In vitro evaluation of valproic acid as an inhibitor of human cytochrome P450 isoforms: preferential inhibition of cytochrome P450 2C9 (CYP2C9)

AIMS

To evaluate the potency and specificity of valproic acid as an inhibitor of the activity of different human CYP isoforms in liver microsomes.

METHODS

Using pooled human liver microsomes, the effects of valproic acid on seven CYP isoform specific marker reactions were measured: phenacetin O-deethylase (CYP1A2), coumarin 7-hydroxylase (CYP2A6), tolbutamide hydroxylase (CYP2C9), S-mephenytoin 4'-hydroxylase (CYP2C19), dextromethorphan O-demethylase (CYP2D6), chlorzoxazone 6-hydroxylase (CYP2E1) and midazolam 1'-hydroxylase (CYP3A4).

RESULTS

Valproic acid competitively inhibited CYP2C9 activity with a Ki value of 600 microM. In addition, valproic acid slightly inhibited CYP2C19 activity (Ki = 8553 microM, mixed inhibition) and CYP3A4 activity (Ki = 7975 microM, competitive inhibition). The inhibition of CYP2A6 activity by valproic acid was time-, concentration- and NADPH-dependent (KI = 9150 microM, Kinact=0.048 min(-1)), consistent with mechanism-based inhibition of CYP2A6. However, minimal inhibition of CYP1A2, CYP2D6 and CYP2E1 activities was observed.

CONCLUSIONS

Valproic acid inhibits the activity of CYP2C9 at clinically relevant concentrations in human liver microsomes. Inhibition of CYP2C9 can explain some of the effects of valproic acid on the pharmacokinetics of other drugs, such as phenytoin. Co-administration of high doses of valproic acid with drugs that are primarily metabolized by CYP2C9 may result in significant drug interactions.

Flat histogram simulation of lattice polymer systems

We demonstrate the use of an algorithm called the Flat Histogram sampling algorithm for the simulation of two-dimensional lattice polymer systems. Thermodynamic properties, such as the average energy or entropy and other physical quantities such as the end-to-end distance or radius of gyration can be easily calculated using this method. The ground-state energy can also be determined. We also explore the accuracy and limitations of this method.

Tensile properties of a bone cement containing non-ionic contrast media

The addition of contrast media such as BaSO4 or ZrO2 to bone cement has adverse effects in joint replacements, including third body wear and particle-induced bone resorption. Ground PMMA containing particles of the non-ionic water-soluble iodine-based X-ray contrast media, iohexol (IHX) and iodixanol (IDX), has, in bone tissue culture, shown less bone resorption than commercial cements. These water-soluble non-ceramic contrast media may change the mechanical properties of acrylic bone cement. The static mechanical properties of bone cement containing either IHX or IDX have been investigated. There was no significant difference in ultimate stress between Palacos R (with 15.0 wt % of ZrO2) and plain cement with 8.0 wt % of IHX or IDX with mass median diameter (MMD) of 15.0 or 16.0 microm, while strain to failure was higher for the latter (p < 0.02). The larger particles (15.0 or 16.0 microm) gave significantly higher (p < 0.001) ultimate tensile strengths and strains to failure than smaller sizes (2.4 or 3.6 microm). Decreasing the amount of IHX from 10.0 wt % to 6.0 wt % gave a higher ultimate tensile strength (p < 0.001) and strain to failure (p < 0.02). Scanning electron microscopy (SEM) showed the smaller contrast media particles attached to the surface of the polymer beads, which may prevent areas of the acrylate bead surface from participating in the polymerization. In conclusion, the mechanical properties of bone cement were influenced by the size and amount of contrast medium particles. By choosing the appropriate amount and size of particles of water-soluble non-ionic contrast media the mechanical properties of the new radio-opaque bone cement can be optimized, thus reaching and surpassing given regulatory standards.

Acute oxalate nephropathy induced by star fruit in rats

In this study, we intend to establish a connection between star fruit and acute oxalate nephropathy and also investigate predisposing factors for its development. Male Sprague-Dawley rats of 180 to 200 g were assigned to four groups; namely, control, experimental, fasting, and water-deprivation groups. The former two groups were subjected to both fasting and water deprivation, whereas the latter two groups were subjected to either fasting or water deprivation, respectively. Except for tap water for controls, the remaining groups were administered 4 mL/100 g of body weight of sour star fruit juice with an oxalate concentration of 2.46 g/dL. After these procedures, serial measurement of serum creatinine levels and kidney pathological examination were performed. Peak serum creatinine levels in the control, experimental, fasting, and water-deprivation groups were 0.50 +/- 0.04, 1.46 +/- 0.26, 0.68 +/- 0.20, and 0.52 +/- 0.08 mg/dL, respectively. The experimental group had a greater peak serum creatinine level (P < 0.05). Mean serum creatinine levels of the experimental group days 0, 1, 2, 3, 4, and 5 were 0.43 +/- 0.03, 1.11 +/- 0.18, 1.31 +/- 0.27, 1.16 +/- 0.28, 0.8 +/- 0.26, and 0.82 +/- 0.28 mg/dL, respectively. Mean serum creatinine levels days 1 to 3 were greater than that day 0 (P < 0.05). Pearson's correlation analysis of peak serum creatinine level and kidney weight for the experimental group showed a significant correlation (R = 0.75; P < 0.05; n = 9). In addition to typical changes of oxalate nephropathy, kidney pathological examination showed many refractile oxalate crystals with all rainbow colors under polarized light microscopy in the experimental group. In conclusion, sour star fruit with abundant oxalate contents could cause acute oxalate nephropathy in rats under the conditions of fasting and water deprivation.

The coronary delivery of marrow stromal cells for myocardial regeneration: pathophysiologic and therapeutic implications

OBJECTIVES

Bone marrow stromal cells contain "adult stem cells." We tested the hypothesis that coronary-infused bone marrow stromal cells may populate the infarcted heart and undergo milieu-dependent differentiation to regenerate functional tissues with different phenotypic features.

METHODS

Isogenic adult rats were used as donors and recipients to simulate autologous transplantation clinically. Myocardial infarction was created by proximal occlusion of left coronary artery in 12 recipient rats. Isolated bone marrow stromal cells were purified, expanded, and retrovirally transduced with LacZ reporter gene for cell labeling. Stromal cells were then infused into the briefly distally clamped ascending aorta of recipient rats 2 weeks after left coronary artery ligation. The hearts were harvested immediately (n = 2) or 4 weeks (n = 10) later to trace the implanted cells and identify their phenotypes.

RESULTS

Viable cells labeled with LacZ reporter gene were identified in 8 recipient hearts. Immediately after cell infusion, the labeled cells were trapped within the coronary capillaries. After 4 weeks, they could be detected individually or in clusters within myocardial scar expressing fibroblastic phenotype or outside the infarction area with morphologic features of normal cardiomyocytes. Some were incorporated into endocardium and capillary endothelium.

CONCLUSIONS

Our findings suggest that bone marrow stromal cells can traffic through the coronary system to the injured heart and form cardiomyocytes or fibroblasts, depending on the specific microenvironment. Endothelial progenitor cells in the stromal cell population may be involved in the postinfarction neovascularization process. Whether therapeutic use of bone marrow stromal cells can improve the myocardial healing and remodeling process after infarction is worthy of further investigation.

Stopped-flow kinetic study of the H2O2 oxidation of substrates catalyzed by microperoxidase-8

We have studied the oxidation of microperoxidase-8 (MP-8) by H2O2 and the subsequent reaction of the intermediates with substrate by stopped-flow experiments. Oxidation of MP-8 by H2O2 gives two intermediates, I and II. The observed rate constant for the formation of I is linearly dependent on [H2O2] and exhibits a bell-shaped dependence on pH with pKa values of 8.90 and 10.60, which are attributed to the deprotonation of MP-bound H2O2 and H2O, respectively. The observed rate constant for the conversion of I to II is independent of [H2O2], but increases sharply at pH>9.0. The predominant forms of the intermediate at pH 7.0 and 10.7 are I and II, respectively. Addition of substrate to the intermediates at pH 9.0 gives rise to three distinct stages, corresponding to the three steps (in decreasing order of rate): I-->II*, II-->MP, and II*-->MP. The rates of these steps are all linearly dependent on the substrate concentration and each individual rate constant has been determined. Substrate reactivity at pH 10.7 covers over two orders of magnitude, ranging from 1.36 x 10(7) M(-1) s(-1) for 1-naphthol to 4.03 x 10(4) M(-1) s(-1) for ferrocyanide. The substrate reactivity is linearly correlated with its reduction potential, indicating that an electron transfer process is involved in the rate-limiting step.

Genetic modification of hematopoietic progenitor cells for combined resistance to 4-hydroperoxycyclophosphamide, vincristine, and daunorubicin

AIM

To investigate whether human peripheral blood hematopoietic progenitor cells (PBPC) modified with human aldehyde dehydrogenase class-3 gene (ALDH-3) and multidrug resistance gene 1 (MDR1) would increase chemotherapy resistance to 4-hydroperoxycyclophosphamide (4-HC) and -glycoprotein effluxed drugs.

METHODS

A bicistronic retroviral vector G1Na-ALDH3-IRES-MDR1 cDNA was constructed and used to transfect the packaging cell lines PA317 by electroporation. CD34+ PBPC were isolated with a high-gradient magnetic cell sorting system (MACS), and then were transfected with supernatant of retrovirus containing human ALDH-3 and MDR1 cDNA. PCR, RT-PCR, Southern blot, Northern blot, FACS, and MTT assay were used to evaluate the transfection and expression of the transgene in target cells.

RESULTS

The bicistronic retroviral vector construction was verified by PCR and restriction endonuclease analysis. Dual drug resistance genes were integrated into the genomic DNA of CD34+ PBPC and expressed efficiently. The efficiency of gene transfection in CD34+ PBPC was tested to be 18 % on colonies. Nested PCR and Neor rescue assay indicated that no helper virus was present in this system. Compared with the untransduced cells, transgene recipient cells conferred 4.5-fold resistance to 4-HC, 6.6-fold and 7.8-fold resistance to P-glycoprotein effluxed drug, vincristine and daunorubicin, respectively.

CONCLUSION

Efficient transduction of two different types of drug resistance genes into human peripheral blood hematopoietic progenitor cells and the co-expression may decrease cumulative myelosuppression of combination chemotherapy.

Ascending aorta to lower limbs revascularization for reoperation via ministernotomy

The extra-anatomic bypasses, femorofemoral or axillofemoral, have been performed in selected patients for lower extremity revascularization of aortoiliac occlusion. However, significant graft occlusion rate does exist and reoperation constitutes an increasing proportion of vascular surgery practice. We presented our experience in a high-risk patient who received bypass surgery for the third time using the ascending aorta as the source of inflow with good result.

Field tracer-transport tests in unsaturated fractured tuff

This paper presents the results of a field investigation in the unsaturated, fractured welded tuff within the Exploratory Studies Facility (ESF) at Yucca Mountain, NV. This investigation included a series of tests during which tracer-laced water was released into a high-permeability zone within a horizontal injection borehole. The tracer concentration was monitored in the seepage collected in an excavated slot about 1.6 m below the borehole. Results showed significant variability in the hydrologic response of fractures and the matrix. Analyses of the breakthrough curves suggest that flow and transport pathways are dynamic, rather than fixed, and related to liquid-release rates. Under high release rates, fractures acted as the predominant flow pathways, with limited fracture-matrix interaction. Under low release rates, fracture flow was comparatively less dominant, with a noticeable contribution from matrix flow. Observations of tracer concentrations rebounding in seepage water, following an interruption of flow, provided evidence of mass exchange between the fast-flowing fractures and slow- or non-flowing regions. The tests also showed the applicability of fluorinated benzoate tracers in situations where multiple tracers of similar physical properties are warranted.

Ocular manifestations of tuberculosis

OBJECTIVE

To present the clinical and histopathologic findings in five cases of tuberculosis (TB) with various ocular manifestations.

DESIGN

Observational case series.

METHODS

Retrospective review of clinical findings, course, and treatment of five patients. Diagnostic techniques, including biomicroscopic, histopathologic, and molecular biologic test results, are presented.

MAIN OUTCOME MEASURES

Visual acuity, slit-lamp biomicroscopy, indirect ophthalmoscopy, and fluorescein angiography results.

RESULTS

The ocular manifestations of TB in our patients included panophthalmitis, endophthalmitis, posterior uveitis with choroidal tubercles, keratitis, and a lid mass. Mycobacterium tuberculosis was identified in four cases in ocular specimens using acid-fast bacilli microscopy and in three cases by culture. Rapid diagnosis using polymerase chain reaction was obtained in one case. Extraocular foci of TB were identified in three cases with an intraocular infection at presentation. No patients had the human immunodeficiency virus (HIV) and none were immunocompromised. Two eyes could not be saved using antituberculous treatment because of delayed diagnosis and treatment.

CONCLUSIONS

In this age of the HIV pandemic, TB is becoming more common. Because it is curable, heightened awareness and better understanding of the disease's ocular manifestations should be of concern to all ophthalmologists.

Role of chicken serum in inhibiting Leucocytozoon caulleryi development in Culicoides arakawae infected by membrane-feeding of infective blood meals

Leucocytozoon caulleryi, the most important pathogen of leucocytozoonsis in several Asian countries, is transmitted by Culicoides arakawae. Although the vector blood meal factors that influence the infectivity of L. caulleryi remain poorly understood, the factors in infected chicken serum remain vital. C. arakawae blood-fed through a membrane were used in this experiment to examine the influence of serum factors on L. caulleryi development. Experimental results indicate that C. arakawae were successfully blood-fed through a chicken-egg-shell membrane and the serum factors in infected chicks significantly affected L. caulleryi sporogony. The inhibition effect of serum factors calculated from sporozoite averages was 53.6% +/- 2.2%. The serum factors, including transmission-blocking antibody, require further detailed study.

Tai Chi Chuan training to enhance microcirculatory function in healthy elderly men

OBJECTIVE

To evaluate cutaneous microcirculatory function in geriatric Tai Chi Chuan (TCC) practitioners.

DESIGN

Case-control study.

SETTING

Community setting.

PARTICIPANTS

Ten elderly male TCC practitioners (mean age, 69.9 +/- 1.5 yr) and 10 sedentary men with matched age and body size (mean age, 67.0 +/- 1.0 yr).

INTERVENTION

The TCC group had practiced TCC for 11.2 +/- 3.4 years (mean +/- standard error of the mean), with an exercise frequency of 5.1 +/- 1.8 times weekly. Each session included 20 minutes of warm-up, 24 minutes of TCC practice, and 10 minutes of cool down.

MAIN OUTCOME MEASURES

A graded exercise test with gas analysis was conducted on a bicycle ergometer for each subject. Skin blood flow (SkBF), cutaneous vascular conductance, and skin temperature were measured at rest and during exercise testing. Plasma nitric oxide metabolite was analyzed before and immediately after exercise.

RESULTS

The TCC group had a 34% higher VO(2)peak than the control group; it also had a higher SkBF, cutaneous vascular conductance, and skin temperature than the control group at rest and during exercise; and it also had a higher level of plasma nitric oxide metabolite than the sedentary group at rest and after exercise.

CONCLUSION

Older TCC practitioners had higher cutaneous microcirculatory function during exercise than did their sedentary counterparts. Moreover, this change may be partially mediated by enhancement of nitric oxide release.

[A bicistronic retroviral vector containing MGMT and MDR1 drug resistance genes transfer into human umbilical cord blood CD34+ cells to improve combination chemotherapy tolerance]

To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human O6-methylguanine-DNA-methyltransferase (MGMT) and multidrug resistance gene (MDR1) increase resistance to 1,3-Bis(2-Chloroethy1)-1-Nitrosourea (BCNU) and P-glycoprotein effluxed drugs, the present authors obtained a full length cDNA fragment encoding MGMT from liver tissue of a patient with cholelithiasis by RT-PCR. A bicistronic retroviral vector G1Na-MGMT-IRES-MDR1 cDNA was constructed and transfected the packaging cell lines GP + E86 and PA317 by electric performation method, using the medium containing VCR and BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD34+ cells were enriched with a high-gradient magnetic cell sorting system (MACS), and then transfected repeatedly with supernatant of retrovirus containing human MGMT and MDR1cDNA under stimulation of hemapoietic growth factors. PCR, RT-PCR, Southern blot, Northern blot, Western blot, FACS and MTT assay were used to evaluate the transfer and expression of the double genes in cord blood CD34+ cells. The cDNA encoding MGMT was verified by DNA sequencing and the bicistronic retroviral vector was confirmed by restriction endonuclease analysis. The purity of cord blood CD34+ cells was approximately 92% and recover rate was 75%, the highest titer of recombinant amphotropic retrovirus in the supernatant was up to 5.8 x 10(5) cfu/ml. The efficiency of gene transduction was 18% and 20% tested by colony formation and PCR, respectively. No helper virus was found by both nested PCR and rescue assay. The results showed that dual drug resistance genes have been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The MTT analysis showed a 4.5 to 7.8-fold increase of resistance of transducted cells to BCNU and P-glycoprotein effluxed drug as compared with the nontransduced cells. This study provided a foundation for ameliorating combination chemotherapy toxicity in tumor clinical trial.