Biocompatibility of xenogeneic bone, commercially available coral, a bioceramic and tissue sealant for human osteoblasts

The drawbacks of freshly harvested autologous bone have resulted in the search for an alternative, capable of supporting osteogenic cell growth. This capability was examined in potential bone graft materials by culturing human osteoblasts on each material. Test materials included rat bone, Surgibone, Ostilit, Biocoral and Tisseel. After 3 days osteoblasts had adhered to all materials, except Ostilit. With increasing time the cells multiplied on the materials, to varying extents. Cell affinity was greatest for rat bone and Tisseel. Fewer cells attached to Biocoral and Surgibone. Thus all the materials, with the exception of Ostilit, were biocompatible for human osteoblasts.

Superficial temporal-artery aneurysm

We report finding at surgery a histopathologically-confirmed superficial temporal-artery aneurysm. To our knowledge, this is the first report of this type of aneurysm in the ophthalmic literature. The ophthalmologist must include this condition in the differential diagnosis of a pulsatile and tender temporal artery, especially when a history of trauma is present.

Malignant pheochromocytoma masquerading as acute pancreatitis--a rare but potentially lethal occurrence

Pheochromocytoma mimicking acute pancreatitis as its initial clinical manifestation is a known, albeit rare, phenomenon. Herein we describe a patient with this occurrence. A striking feature was pronounced hyperamylasemia, almost exclusively of the S-type. Our theory is that the pheochromocytoma caused a catecholamine-induced cardiomyopathy, which contributed to failure of the left ventricle; pulmonary edema and release of S-type amylase from hypoxic lung tissue occurred subsequently.

ADP causes partial degranulation of platelets in the absence of aggregation

Whole blood flow cytometry has revealed that platelets undergo partial degranulation in response to ADP, in the absence of aggregation, as evidenced by the expression of the P-selectin and CD63 antigens of the alpha-granule and lysosomal membranes respectively. With maximum ADP (10(-5) M) fibrinogen bound to 76.1 +/- 7.2% of platelets but P-selectin and CD63 antigen were expressed on 26.9 +/- 9.8% and 8.6 +/- 3.5% of platelets respectively. Maximum fibrinogen binding, P-selectin and CD63 expression induced by alpha-thrombin were 96.1 +/- 1.4%, 92.8 +/- 2.3% and 77.6 +/- 9.7% respectively. beta-thromboglobulin release from the ADP-stimulated platelets correlated closely with the expression of P-selectin and CD63 (r = 0.98 +/- 0.02 for both antigens). No platelet aggregates were seen by flow cytometry and the absence of aggregation was confirmed by single cell counting. Addition of the GPIIb-IIIa antagonist echistatin, at concentrations that totally blocked fibrinogen binding to ADP-stimulated platelets, had no effect on the expression of the granule membrane antigens. The partial degranulation of normal platelets was independent of thrombin generation since it was not inhibited by hirudin (5 units/ml). In conclusion, ADP is capable of causing partial degranulation of platelets independently of aggregation, fibrinogen binding or thrombin generation. Thus release of potent procoagulant, vasoactive and mitogenic substances from the platelets could continue in the presence of thrombin inhibitors and GPIIb-IIIa antagonists.

A scanning electron microscopic study of the normal development of the chick wing from stages 19 to 36. A supplement to the Hamburger and Hamilton staging system

The purpose of a staging system is to stage embryos by morphology rather than chronology. This is particularly useful when embryos do not develop exactly synchronously, as in the case of the chick. At present the Hamburger and Hamilton (1951) series is universally used to stage chick embryos. The aim of the present study was to provide a series of morphological descriptions of the normal stages of development of the chick wing bud from stages 19 to 36, and to correct some errors of the original system which may be overlooked by those new to the chick wing bud as an experimental model, and who rely primarily on the Hamburger and Hamilton stage series. In addition, Summerbell's (1976) observations on the appearance of the cartilaginous elements made from alcian green-stained whole mounts have been correlated with the external appearance of the wing bud to provide a more complete understanding of the skeletal development that influences, and to some degree accounts for, the changes in external morphology. Scanning electron microscopy (SEM) has been used to obtain images of much greater resolution and detail than those available from Hamburger and Hamilton, whilst using comparable magnifications to those attainable using conventional dissecting microscopes. The number of somites across which the proximal part of the wing bud extends has been provided as a measure of the limb width at early stages (19-24). At certain stages there were clear differences between the characteristic wing bud features described by Hamburger and Hamilton and those observed in the present study.(ABSTRACT TRUNCATED AT 250 WORDS)

Epinephrine sensitizes human platelets in vivo and in vitro as studied by fibrinogen binding and P-selectin expression

Epinephrine (Epi) infusion influences platelet activation markers in vivo, but in vitro studies have mainly examined supraphysiological Epi concentrations and have yielded conflicting results. In this study whole-blood flow-cytometric measurements of platelet fibrinogen binding and P-selectin expression were used to compare enhancement of ADP (0.1 to 10 mumol/L)-induced platelet activation by Epi infusion in vivo (0.1 and 0.4 nmol.kg-1.min-1) and by Epi in vitro (10 and 50 nmol/L) in nine healthy volunteers. ADP caused concentration-dependent increases in the percentage of platelets that bound fibrinogen (from 4.4 +/- 0.9% to 69.9 +/- 4.2%) and that expressed P-selectin (from 4.5 +/- 0.5% to 44.2 +/- 3.8%). Fibrinogen and P-selectin binding indices (FgBI and PSBI; calculated from mean fluorescence intensity and percentage of positive cells) also increased from 0.18 +/- 0.03 to 11.70 +/- 1.99 for FgBI and from 0.22 +/- 0.03 to 2.34 +/- 0.29 for PSBI. Epi concentration-dependently enhanced fibrinogen binding and P-selectin expression in vitro (by approximately 30% at the midportion of the ADP curve at 10 nmol/L Epi; P < .001 for both by ANOVAs). High-dose Epi infusion enhanced FgBI similarly and increased maximal P-selectin expression by 38%. Epi (50 nmol/L in vitro) enhanced platelet activation further, whether samples were taken with or without prior Epi infusion. Total expression of glycoprotein IIb/IIIa was unaffected by Epi infusion, but glycoprotein Ib expression per platelet was reduced (P < .05). These in vivo and in vitro effects of Epi on platelet responses to agonist stimulation indicate a prothrombotic potential for sympathoadrenal activation in humans.

Systemic and renal effects of nifedipine in cyclosporine-associated hypertension

Cyclosporine induces hypertension and wide-spread vasoconstriction after transplantation in addition to reducing kidney function. We studied hemodynamic, renal, and hormonal effects of monotherapy with nifedipine XL (n = 37) in liver transplant recipients within a year after transplant (median, 4.4 months). Systemic hemodynamics were determined with thoracic electrical bioimpedance. Blood pressure before therapy was 172 +/- 4/108 +/- 2 mm Hg. Sixty-four percent of recipients achieved blood pressures less than 140/90 mm Hg mediated by a fall in systemic vascular resistance index (2427 +/- 245 dyne.s.cm-5.m-2 in responders versus 2905 +/- 281 in nonresponders, P < .01). Despite the fall in systemic vascular resistance, glomerular filtration rates were not changed during nifedipine therapy, as measured by both creatinine and iothalamate clearances. Urinary prostacyclin (6-ketoprostaglandin F1 alpha) was suppressed below normal from 2468 +/- 323 ng/d before transplant to 1103 +/- 99 ng/d (P < .01) after transplant and did not change during nifedipine therapy. Urinary thromboxane B2 and plasma renin activity also fell after transplant and remained low during nifedipine. These data demonstrate that nifedipine can reverse systemic vasoconstriction associated with hypertension after transplantation. Systemic effects were not transmitted to the kidney sufficiently to improve glomerular filtration rate or reverse hormonal changes within the kidney. Hence, vascular and functional regulation of the kidney was dissociated from the systemic circulation during nifedipine administration after transplantation.

Minitracheostomy: an alternative to "blind" endotracheal suctioning

The critical care nurse is frequently challenged to clear respiratory secretions for patients with thick, copious mucous and a weak cough. The traditional interventions nurses use are chest physiotherapy, incentive spirometry, and "blind" endotracheal suctioning to facilitate the removal of secretions, but these are sometimes ineffective and cause complications. Nurses who identify patients needing a more effective way to remove secretions can request consideration of a new method, suctioning through a minitracheostomy.

Early embryonic angiogenesis in the chick area vasculosa

The rate and pattern of growth as well as vessel ultrastructure of the area vasculosa were examined in the chick. The embryos were grown in shell-less culture after 3 d in ovo and staged according to Hamburger & Hamilton (1951) and the rate of increase in the diameter of the area vasculosa was measured. This revealed an increase in the area vasculosa diameter of 0.4 +/- 0.02 mm h-1 (n = 62) for embryos between stages 15 and 20. To determine the growth pattern of the sinus terminalis (the advancing edge of the area vasculosa), a marked length of the sinus was photographed at hourly intervals over a period of 9 h. It was found that this vessel grows by new vessels forming external to the sinus in the form of parallel plexuses, one of which then replaces the original sinus as the major route of bloodflow. Ultrastructurally the capillaries of the area vasculosa were simple tubes of endothelial cells, lacking a basement membrane. The endothelial cell cytoplasm contained only a few organelles, mainly mitochondria and rough endoplasmic reticulum. These findings indicate that the chick area vasculosa capillaries bear similar structural and growth characteristics to those associated with tumour angiogenesis and suggest that they may prove to be a useful model system for studying the factors involved in pathological angiogenesis.

Profound platelet degranulation is an important side effect of some types of contrast media used in interventional cardiology

BACKGROUND

Thrombotic complications occurring during coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) are relatively frequent and can be influenced by the type of radiographic contrast media used. Low osmolar contrast media (LOCM), both ionic and nonionic, have been considered to be safer than the older high osmolar contrast media (HOCM), causing less haemodynamic and symptomatic side effects. Recently, however, nonionic LOCM have been associated with an increased incidence of thrombotic events, including coronary occlusion and stroke.

METHODS AND RESULTS

The effects of commonly used contrast media on platelets in native blood were investigated using immunolabeling and flow cytometry to detect platelet activation in vitro. A nonionic LOCM (Omnipaque) caused profound platelet degranulation in nearly 80% of platelets compared with 2 to 3% of platelets in the control. Conversely, an ionic HOCM (Urografin) caused only 25% degranulation, whereas an ionic LOCM (Hexabrix) caused no platelet activation and, furthermore, it inhibited the effects of thrombin on platelets. Platelet degranulation, quantified by immunolabeling, was paralleled by release of beta-thromboglobulin and platelet factor 4 from platelet alpha-granules. Blood from patients anticoagulated with heparin and pretreated with standard-dose aspirin in preparation for PTCA showed the same pattern of contrast media-induced platelet activation as normal subjects.

CONCLUSIONS

These results suggest that the type of contrast media used during invasive imaging of the vasculature could have a significant effect on platelets. Platelet degranulation within a PTCA-damaged vessel would be increased by a nonionic contrast medium, releasing procoagulant molecules and platelet-derived growth factors into the damaged vessel lumen, which might contribute to acute thrombosis and the initiation of the restenosis process.

Association of Mycobacterium paratuberculosis infection with reduced mastitis, but with decreased milk production and increased cull rate in clinically normal dairy cows

Approximately 45 Holstein cows that were Mycobacterium paratuberculosis-positive on the basis of fecal culture results were maintained at any one time in a 210-cow dairy herd. Farm management participated in the New York State Paratuberculosis Eradication Program. Paratuberculosis-positive cows were grouped separately from paratuberculosis-negative cows, but they were otherwise managed identically. During a 1-year study, 180 paratuberculosis-negative cows and 113 clinically normal paratuberculosis-positive cows were identified. Quarter milk samples (n = 6,100) were aseptically collected for microbiologic culture of mastitis pathogens from paratuberculosis-negative cows, and 3,129 quarter samples were obtained from paratuberculosis-positive cows. Dairy Herd Improvement Association (DHIA) records were used to monitor milk somatic cell count linear scores, mature equivalent milk production, new mastitis infections, and chronic mastitis infections. For second-lactation cows greater than 100 days in milk production, and increasing with age beyond that point, paratuberculosis-positive cows had lower mature equivalent milk production than did negative herdmates. Rates of new and chronic mastitis infections, as measured by DHIA linear scores were significantly (P < 0.05, P = 0.05, respectively) lower in cows with nonclinical paratuberculosis. Infected cows were culled from the herd at a faster rate than were paratuberculosis-negative herdmates. Therefore, paratuberculosis was associated with financial loss attributable to reduced milk production and increased culling of infected cows.

Procedures for mastitis diagnosis and control

Procedures for mastitis diagnosis and control include culturing individual cow and bulk tank milk samples, antibiotic susceptibility testing, and evaluation of somatic cell count reports and clinical mastitis treatment records. Integrated use of such procedures is necessary for effective mastitis diagnosis and control.

Evaluation of whole blood flow cytometric detection of platelet bound fibrinogen on normal subjects and patients with activated platelets

Activated platelets can be detected by measuring platelet-bound fibrinogen in a whole blood, flow cytometric assay, using a fluorescently-conjugated polyclonal antibody. Fibrinogen binding to unstimulated platelets from normal subjects was low in this assay, as was expression of the CD63 antigen. Single cell counting of samples prepared for flow cytometric analysis showed platelet aggregates do not form during the assay procedure. Immune complexes were not seen, and fibrinogen binding to the platelets was unaffected by the CD32 MAb, IV.3. Artefactual activation of the unfixed samples could be minimised by control of phlebotomy, time and temperature of incubation. Variations in platelet count in the range 140-430 x 10(9) 1(-1) and in plasma fibrinogen in the range 2-6 g 1(-1) did not affect the assay results. Comparison of fibrinogen binding with expression of CD63 antigen on normal platelets, stimulated with agonists in vitro, demonstrated that fibrinogen binding detects an earlier stage of platelet activation. Platelet bound fibrinogen was shown to be sensitive in detecting small numbers of activated platelets in clinical samples in twelve patients on intensive care, four undergoing haemofiltration. The patients had a significantly higher median percentage of circulating platelets with bound fibrinogen (p < 0.005), but fibrinogen binding was significantly lower (p < 0.02) in response to 10(-5) M ADP, compared to twelve age-matched normal controls.

Effect of ethylene oxide sterilization on human demineralized bone

Demineralized human bone used as an autologous bone graft substitute is ethylene oxide sterilized, which is reported to reduce the bone's osteoinductive potential. To determine the minimum sterilization time required and the effect of ethylene oxide on bone's osteoinductive capacity and chemical structure, samples were exposed to ethylene oxide for different times (5-240 min). Results showed that 1 h exposure sterilized the bone (assessed by Attests). This exposure time reduced the bone's osteoinductive potential and caused surface ultrastructural changes. These findings raise questions concerning the suitability of ethylene oxide for sterilizing demineralized human bone.

Antero-posterior skeletal patterning is not dependent on continuity of the apical ectodermal ridge in the chick wing bud

The mechanism of antero-posterior specification of limb skeletal pattern is still controversial. If, as proposed by the ZPA model, a diffusible morphogen does exist, its route of passage across the limb field has not been resolved. To investigate the contribution of the apical ectodermal ridge (AER) to the control of antero-posterior pattern formation, we examined the consequences of small wounds made to the AER. The wound response was investigated by means of resin histology and scanning electron microscopy; subsequent limb development and cartilage pattern were examined in whole-mount preparations. Although regrowth of the bilaminate dorsal and ventral ectoderm over the wound occurred within 15 h, the more highly differentiated pseudostratified columnar epithelium of the AER did not reform, and there was subsequent retardation of limb outgrowth at the wound site. At 10-11 days of development, the appearance of the limbs allowed them to be placed into one of three categories; presence of supernumerary elements, accentuation of an inter-digital cleft, or normal. The first of these categories included limbs in which digit 3 had bifurcated such that the sum of the parts of the resultant digital skeleton was greater than that which forms in a normal limb. Since in all of the experimental limbs all skeletal elements were present, we propose that continuity of the AER is not a pre-requisite for antero-posterior skeletal pattern formation in the chick wing.

The culture of human osteoblasts upon bone graft substitutes

In order to assess the ability of six potential bone graft substitutes to support the growth of human osteoblasts, these cells were grown in culture and then plated onto fragments of the six materials and cultured for a further period of 15 days. Tests to confirm the osteoblastic phenotype of the cells included spectrophotometric alkaline phosphatase assay; Western blotting of secreted osteocalcin, osteonectin, bone sialoprotein, and collagen type I; and mineralization within the cultures provided with a supplemented medium. Cells were seeded onto the materials in 24-well plates (Nunc, Naperville, IL) at density levels 12,500 cells/cm2 and 25,000 cells/cm2. Specimens were examined after the 15-day culture period by scanning electron microscopy. At a seeding density of 12,500 cells/cm2 results showed that the human osteoblasts had greatest affinities for demineralized rat bone and demineralized Surgibone, whilst few osteoblasts were found attached to Pyrost, Surgibone, or coral. The collagen matrix of Callopat hydrated in the culture media exposing the hydroxyapatite crystals within it, and these became the foci for cell attachment and growth. At a seeding density of 25,000 cells/cm2 the osteoblasts had attached to and proliferated upon the surfaces of all the materials, forming multilayers, with the exception of Surgibone. These experiments demonstrated that all the materials, with the exception of nondemineralized Surgibone, were biocompatible for human osteoblasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and renal hemodynamic differences between FK506 and cyclosporine in liver transplant recipients

Immunosuppression after transplantation is complicated by hypertension and nephrotoxicity, reflecting widespread vasoconstriction associated with CsA. FK506 is a novel alternative immunosuppressive agent, structurally unrelated to CsA. These studies compared systemic and renal vascular changes developing in the initial 4 weeks after liver transplantation in patients treated with FK506 (plus PRED) and CsA (plus PRED and AZA). We studied arterial pressure, cardiac index (pulsed doppler ultrasound), and systemic resistance index (SVRI) before and weekly after liver transplant in 32 patients treated with CsA (2 mg/kg initial dose plus PRED; median dose at week 4, 30 mg/day) and 14 patients treated with FK506 (0.15 mg/kg/day initial dose and PRED; mean week 4 dose, 12.5). Renal plasma flow and glomerular filtration rate (GFR) were measured by clearance of para-amino hippurate and 125-iothalamate. Renin activity, aldosterone, and urinary prostanoids were measured by RIA. Pretransplant pressures and hemodynamics reflected low SVRI and increased cardiac index typical of end-stage liver disease. After transplantation, SVRI and pressures rose in both groups, but after week 2, SVRI was lower in patients treated with FK506. This was associated with less prevalent clinical hypertension during the subsequent 4 months (4/14 FK506 (28%) vs. 25/32 (78%) CsA, P < 0.01). By contrast, renal blood flow and GFR fell in both treatment groups similarly, whereas renal vascular resistance rose. Urinary 6-keto-PG-F1-alpha was suppressed in all transplant recipients, but to a greater degree in FK506-treated patients. This value correlated directly to post-transplant GFR (r = 0.48, P < 0.001). These data indicate that FK506-based immunosuppression differs from CsA by inducing less systemic vasoconstriction and hypertension. Renal vasoconstrictive effects were at least as great as those seen with CsA, however, and indicate that nephrotoxicity will remain a common feature to both regimens.

A clinicopathologic correlative study of noncontact transscleral Nd:YAG cyclophotocoagulation

We studied the histopathologic changes of three eyes enucleated two weeks, eight weeks, and 17 months, respectively, after noncontact Nd:YAG cyclophotocoagulation. The histologic findings at two weeks were destruction of the nonpigmented and pigmented ciliary body epithelium, occlusion of the capillaries of the ciliary processes, and ciliary body stromal necrosis in the region of the processes. Hyperplasia of the pigmented and nonpigmented epithelium, fibrosis and near total atrophy of the ciliary processes, and partial atrophy of the ciliary muscles were present at eight weeks and 17 months. We concluded that application of treatment 1.0 to 1.5 mm posterior to the corneoscleral limbus selectively destroys the pars plicata, and that, histologically, the mechanism for reducing intraocular pressure appears to be destruction of ciliary processes with reduction of aqueous formation.

Matrix diffusion effects in the cleanup of heterogeneous aquifers

Simple mathematical models are developed to account for the rather slow mass transport of nonaqueous phase liquid (NAPL) into aqueous solution in groundwater during flushing operations. The models are based on the assumption that this bottleneck in the process is associated with diffusion in the aqueous phase in the porous medium from the location of the NAPL drops/ganglia in a region of relatively low permeability out into a region of substantially higher permeability, somewhat analogous to diffusion from a block of porous rock into a nearby fracture, where the fracture system overwhelmingly dominates the overall permeability. The models include batch flushing, flushing in a laboratory column, and a one-dimensional model for flushing by means of a single recovery well.

Migration of pollutants in groundwater. VI. Flushing of DNAPL droplets/ganglia

Models for describing the flushing of DNAPL from contaminated aquifers are developed, and the dependence of the calculated cleanup times on the model parameters is explored. Diffusion transport from isolated DNAPL droplets, from low-permeability porous spherical domains containing distributed DNAPL droplets, and from low-permeability porous planar lamellae containing distributed DNAPL is analyzed, and the resulting expressions then coupled with the equations for advective transport of dissolved VOC by means of natural uniform flow and a system of injection and recovery wells generating a two-dimensional flow field. The models are readily run on currently available microcomputers. The results of computations with the models are consistent with the severe tailing and slow rates of remediation which are generally observed when DNAPLs are removed by flushing.