Haemostatic factors and atherogenesis

It is increasingly realised that fibrin deposition and fibrin lysis are major factors in vascular pathology. In addition to thrombotic occlusion fibrin is a component of atherosclerotic lesions, but the increased interest in components of the haemostatic system was mainly triggered by clinical use of fribrinolytic agents, and the problems of re-stenosis following angioplasty. This review focuses on the main components of the fibrinolytic system--tissue plasminogen activator (tPA), urokinase (uPA) and plasminogen activator inhibitor (PAI-1)--and on thrombin. These factors are not only involved in fluid phase clotting and clot lysis; they react specifically with cells and matrix components. During the last 5 years, the main period under review, there have been numerous studies on their interactions with endothelial and smooth muscle cells in culture, in whole tissues and in vivo, and with arterial extracellular matrix of which a major component is fibrin. Plasminogen activators bind to cell surface receptors, influence cell migration and release active thrombin from fibrin. Thrombin emerges as a pluripotent factor which modulates many aspects of endothelial and smooth muscle cell behaviour, including release and synthesis of fibrinolytic components, and stimulation of cell proliferation.

Prothrombin-related antigens in human aortic intima

Most plasma proteins are present in both normal and atherosclerotic intima, and their concentrations in intimal interstitial fluid are directly related to plasma concentration and molecular size. All intimal samples also contain soluble fibrin-fibrinogen-related antigens, consisting of variable mixtures of fibrinogen and fibrinogen and fibrin degradation products; the extracted washed tissue contains insoluble fibrin. It appears that the fibrinogen is subjected both to degradation and to conversion to fibrin, which in turn undergoes lysis. Biochemically, insoluble "fibrin" can be detected by incubating the washed tissue with plasmin, and assaying the fibrin degradation products that are released; they are released from all samples, including small amounts from normal intima. The fibrin could arise by incorporation of a mural fibrin clot and/or clotting of the fibrinogen within the intima, which contains a "cocktail" of clotting-related factors including prothrombin/thrombin-related antigens, antithrombin III (AT III), and other protease inhibitors: in recent experiments stripped intima was immediately treated with ethylenediaminetetraacetic acid, minced, extracted with Tris-buffered saline, and the extracts analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting with antisera to prothrombin and AT III. Surprisingly, all blots treated with antiprothrombin antisera showed large bands migrating with free thrombin (36 to 37 kDa) and prothrombin (74 kDa) and four intermediate bands. In addition, in all 10 samples examined a band of high molecular mass (170 kDa) but variable intensity was present. This 170-kDa band comigrated with the major band reacting with anti-serum to AT III. The theoretical 1:1 thrombin:AT III complex (98 kDa) was not detected. Thus active thrombin appears to be present in intima, and this may be a highly atherogenic factor, both causing fibrin deposition and acting as a potent mitogen for arterial smooth muscle cells.

Glycine activation of human homomeric alpha 1 glycine receptors is sensitive to pressure in the range of the high pressure nervous syndrome

The effect of hyperbaric pressure on the inhibitory glycine receptor has been investigated in voltage-clamped Xenopus oocytes microinjected with cRNA encoding the human alpha-1 glycine receptor subunit. Heterologous expression of the human alpha-1 subunit generated functional glycine-gated channels with properties typical of native receptors. Glycine elicited a concentration-dependent inward current which reversed polarity at -25 mV and was antagonised by nanomolar concentrations of strychnine. Concentration-response curves established for the homomeric alpha-1 glycine receptor at 5, 10 and 15 MPa were progressively shifted to the right with respect to the concentration response curve established at atmospheric pressure (0.1 MPa). Pressure had no effect on the maximal response. The EC(50) values at 0.1, 5, 10 and 15 MPa were 190 mu M, 222 mu M, 338 mu M and 482 mu M, respectively. The results demonstrate that a receptor comprised solely of the human alpha-subunit is sensitive to pressure in the range that affects divers and at which the native rat spinal cord receptor is affected. This finding is discussed in the context of the postulated binding sites for glycine and the implications for the design of drugs to protect divers from the effects of pressure.

Health-care reform and its impact on African-American surgical specialists

Since 1960, numerous concepts of health-care reform have been submitted to the US Congress and the American public with different viewpoints and objectives. The priority for the US Congress to pass a bipartisan health-reform plan has been circumvented by the newly elected majority Republican Congress. Nevertheless, health-care cost containment, quality control, and health-care delivery concepts have been implemented gradually into the concept of competitive managerial health care. A few of the serious problems in the African-American community are the efficiency and quality of the health-care delivery system and the effects of managed care on African-American primary physicians and surgical specialists. The critical shortages of this group, especially the latter, may create a dilemma in the implementation of a quality surgical care delivery system. The Association of American Medical Colleges, the American College of Surgeons, and other affiliating organizations should become sensitized to the African-American community's health needs, deficiencies, and the rational institution of an equitable, efficient, comprehensive, and quality health-care plan coupled with a sustained and increasing supply of certified, diversified, and experienced African-American surgical manpower in company with family practice physicians and primary care physicians.

The effects of lumbosacral support belts and abdominal muscle strength on functional lifting ability in healthy women

STUDY DESIGN

This study focused on lumbosacral support belts, abdominal muscle strength, and lifting ability in healthy women. Subjects underwent manual muscle testing to determine muscle strength and performed lifting procedures to determine lifting capacity.

OBJECTIVES

The purpose of this study is threefold: 1) to determine the effectiveness of lumbosacral support belts in improving lifting ability in healthy women, 2) to determine if lumbosacral support belts are more effective for those with weak abdominals than those with strong abdominals, and 3) to determine if the maximum amount of weight varies with abdominal muscle strength.

SUMMARY OF BACKGROUND DATA

In a review of published literature, one study has addressed the relationship of lumbosacral support belts and lifting capacity. However, no study has examined the use of lumbosacral support belts and lifting capacity in a female population.

METHODS

A convenient sample of 69 healthy women, aged 20 to 40 years, participated in this study. Subjects were categorized into one of three groups based on lower and upper abdominal muscle strength. Each subject then performed two lifting procedures, one with a lumbosacral support belt and one without, to determine two maximum lifts.

RESULTS

Women between the ages of 20 and 40 years could lift approximately 1.0 kg more weight from the floor to waist height with the lumbosacral support belt. The maximum weight lifted varied with abdominal strength. Lumbosacral support belts were not more effective for those with weak abdominals than those with strong abdominals.

CONCLUSIONS

When applied properly and used in conjunction with proper lifting technique, lumbosacral support belts slightly improved lifting ability in healthy women. The magnitude of the increase, although statistically significant, is not sufficient to advocate the use of lumbosacral support belts to increase lifting capacity.

The nurse's role in diagnosing and treating onychomycosis

Onychomycosis involves fungal invasion of the nail unit via the nail bed or nail plate. Nurses play an important role in diagnosing the disease, managing it, and educating patients about it. Newer oral antifungal agents have increased success rates with shortened treatment times.

Determination of ceftiofur and its desfuroylceftiofur-related metabolites in swine tissues by high-performance liquid chromatography

An HPLC method was developed and validated for the determination of ceftiofur-related metabolites that have the potential to be microbiologically active in swine muscle, kidney, liver and fat. Its performance was evaluated against incurred-residue swine tissues. This method is based on the cleavage of the disulfide and/or thioester bonds between the metabolites and their conjugate sulfur containing moiety using dithioerythritol to yield desfuroylceftiofur, and further stabilization to desfuroylceftiofur acetamide. The limit of quantitation was 0.1 micrograms ceftiofur equivalents/g tissue. The assay is specific for ceftiofur-related metabolites when evaluated against commercially available antibiotics for swine.

Elastoderma

Elastoderma is an exceedingly rare condition that is characterized clinically as an acquired localized laxity of skin resembling cutis laxa and histologically as an excessive accumulation of pleomorphic elastic structures within the dermis. We report the case of a 27-year-old white man with a 2-year history of lax, extensible, wrinkled skin with areas of protrusion and ulceration localized to the anterior aspect and back of the neck. Histologic examination of specimens from the affected area revealed increased masses of intertwined thin, elastic fibers without calcification in the papillary and upper reticular dermis. Transmission and scanning electron microscopy demonstrated irregular deposition of elastic material at the periphery of elastic tissue fibers, with grapelike globular structures. To our knowledge, this is the second reported case of elastoderma.

Fibrinogen, fibrin and the arterial wall

Virtually all plasma proteins, including fibrinogen, low density lipoprotein and lipoprotein(a), are present in normal arterial intima and in atherosclerotic lesions, and their concentrations are related to plasma concentrations. Fibrin is also a significant component of many lesions, particularly early proliferative (gelatinous) lesions, where it may be muscle cells migrate and proliferate, bind thrombin, and are a source of fibrin degradation products (FDPs), which are mitogenic. Very recent studies suggest that free a-thrombin may be present in lesions despite an apparent excess of antithrombin III, so this may promote fibrin formation within the lesion. Furthermore, fibrinolysis and FDP generation may be mediated by catheptic enzymes in addition to plasmin.

Economic issues for African-American surgical specialists in solo or group practices

This clinical research plan was designed to evaluate the predictable and current developments, growth, and stability of the economic status of part-time or full-time African-American practicing surgeons. In many communities throughout the United States, the economic successes of certified or experienced black surgical specialists are inhibited or modified by mistrust, jealousy, professional disengagements, prejudices, and self-hatred by black and white physicians and lay African Americans. Nevertheless, there are subtle and overt evidences of increasing satisfactory and above average associative interprofessional relationships between African-American physicians and surgical specialists. One hundred African-American surgical specialists from thirty-four communities in the United States were interviewed at periodic intervals over a period of three decades. Recommendations for improvements and changes are presented.

Lipids and plasma fibrinogen: early and late composition of the atherosclerotic plaque

Raised levels of plasma low density lipoprotein, lipoprotein (a), and fibrinogen have emerged as major risk factors for myocardial infarction and atherosclerosis. In this brief review some of their interactions with arterial intima are discussed. All the plasma macro-molecules appear to be present even in normal intima, and to cross the endothelium in healthy, young experimental animals by vesicular transport. The precursor of large fibrous plaques appears to be the gelatinous lesion, which is characterized by oedema, accumulation of large amounts of low density lipoproteins and fibrinogen in the expanded interstitial fluid space, deposition of fibrin, and smooth muscle cell proliferation. It is postulated that deposition of fibrin may be a key event, stimulating smooth muscle cell proliferation by providing a scaffold for migration, a source of fibrin degradation products which are mitogenic, and binding thrombin. Fibrin may also be a factor in lipid accumulation because it binds lipoprotein (a) with high affinity, and may also bind low density lipoprotein.

Effect of infrared analyzer homogenization efficiency on repeatability of uncorrected fat A and fat B signals

Poor repeatability by infrared milk analyzers may be caused by inefficient homogenization as a result of light scattering and the Christiansen effect. The objectives of this study were to identify instruments with good and poor homogenization efficiency and to determine if a difference exists in repeatability performance between instruments with good vs poor homogenization efficiency. Unhomogenized and homogenized portions of the same milk were tested 20 times consecutively on 22 instruments. An instrument was considered to have poor homogenization efficiency if the mean difference in the uncorrected signal between unhomogenized and homogenized portions of the same milk was > or = 1.43% of the fat test (i.e., > or = 0.05% at 3.5% fat). Instruments were evaluated for repeatability by calculating the sample standard deviation and the range of the latter 19 uncorrected readings for unhomogenized and homogenized milks. When repeatability was evaluated as a function of homogenization efficiency, there was a significant (p = 0.001) correlation between poor homogenization efficiency and poor repeatability when testing unhomogenized milk but not when testing homogenized milk. Improved homogenizer performance within infrared milk analyzers is needed to improve the repeatability of raw milk testing.

Fibrin deposition and fibrin degradation products in atherosclerotic plaques

Soluble fibrin/fibrinogen-related antigens and insoluble fibrin are present in virtually all samples of human aortic intima. Components of the soluble fraction were identified by SDS-PAGE and immunoblotting with specific antisera. The fibrinogen was characterized by increased proportions of low molecular mass (Mr) species (300 and 280 kD), the FDP by fragments DY and DD derived from crosslinked fibrin, and by fragment E that lacked fibrinopeptide A (FPA). Experiments suggest that fibrin is formed in situ, and free thrombin was present in all 10 samples analysed for prothrombin-related antigen (PtRA). Fibrin-derived fragment E is mitogenic, so fibrin degradation may provide continuing stimulation of smooth muscle cell (SMC) proliferation.

Effect of infrared analyzer homogenization efficiency on linearity of uncorrected fat A and fat B signals

The objective of the survey was to determine if poor homogenizer performance causes nonlinear behavior of the uncorrected fat A or fat B signal that is not detected when an instrument's residual nonlinearity is determined by using dilutions of homogenized milk instead of unhomogenized milk. Unhomogenized and homogenized (17238 kPa) portions of the same 6.1% fat milk were tested on 20 instruments to determine homogenization efficiency. Instruments with differences of > or = 0.087% fat between homogenized and unhomogenized portions of the same milk had inefficient homogenization, on the basis of criteria established in a previous study. Four and 12 instruments out of 20 demonstrated inefficient homogenization for the fat A and fat B channels, respectively. Uncorrected signal linearity for the fat channels was evaluated quantitatively by using a series of dilutions of homogenized (17238 kPa) and unhomogenized milks. Most instruments passed the linearity evaluation for dilutions of either homogenized or unhomogenized milk, even though many of the same instruments failed the homogenization efficiency evaluation. Thus, using dilutions of homogenized milk is valid for linearity evaluation of instruments being used for testing unhomogenized milk in the range of fat concentrations used for payment testing.

Gout masquerading as rheumatoid vasculitis

A 30-year-old Mexican woman had rash, deep ulcerations of her lower extremities, and debilitating polyarthritis. Her disorder simulated rheumatoid vasculitis, but serum rheumatoid factor was absent. The diagnosis of gout was confirmed by uric acid crystals in joint fluid and skin biopsy specimens and by x-ray crystallography. The age and sex were unusual for a patient with gout, and she had none of the commonly associated metabolic defects. This unique presentation for urate arthropathy needs further study.

The effect of high pressure on glycine- and kainate-sensitive receptor channels expressed in Xenopus oocytes

The effect of high pressure on the response to glycine or kainate of voltage-clamped Xenopus oocytes micro-injected with messenger-RNA derived from either rat spinal cord or whole brain, respectively, has been investigated. Current responses were measured at 1 bar (= 10(5) Pa), 50 bar, 100 bar and 150 bar, with PO2 fixed at 1 bar and the balance helium. Glycine elicited a depolarizing current response which was antagonized by nanomolar concentrations of strychnine. The responses reversibly desensitized, with a decay constant of 0.01 s-1, when glycine concentrations greater than 250 microM were used. The decay constant was insensitive to both glycine concentration and pressure. Resensitization was complete within 4 min. Kainate elicited a depolarizing current which was non-desensitizing. The response was slightly sensitive to glutamate diethyl ester (50 microM), which increased the EC50 by 25%. The action of glycine was highly pressure sensitive. The dose-response curves established at 50 bar, 100 bar and 150 bar were shifted progressively to the right, with no effect on the maximal current. The EC50 increased from 216 microM to 296 microM at 50 bar, to 345 microM at 100 bar, and to 425 microM at 150 bar. The action of kainate was unaffected by pressure. No shift in the dose-response curves was established, nor was there any effect on the maximum current. The EC50 was 113 microM at 1 bar, and 111 microM at both 50 bar and 100 bar.(ABSTRACT TRUNCATED AT 250 WORDS)

Presence of growth-stimulating fibrin degradation products containing fragment E in human atherosclerotic plaques

The key event in the formation of stenosing atherosclerotic lesions is widely thought to be smooth muscle cell proliferation, but the factors primarily responsible for initiating this remain uncertain. Previously we have shown that aqueous extracts of proliferative types of human atherosclerotic plaque stimulate cell proliferation in the chick chorioallantoic membrane (CAM). This has been attributed largely to the fibrin degradation products in the extracts, components removeable by affinity chromatography. We now demonstrate that the fibrinogen content of the extract, removeable by clotting out with thrombin, also makes a contribution to the activity by forming fibrin on the surface of the CAM. Affinity chromatography experiments using anti fragment D and E antisera indicate that activity resides in the E-containing fibrin fragments, consistent with previous work with FDP prepared in vitro.

Topical antifungal drugs in the treatment of tinea pedis, tinea cruris, and tinea corporis

Topical treatment of fungal infections took a step forward in the 1960s with the introduction of biologically active agents with specific antifungal mechanisms of action. Most modern broad-spectrum antifungal agents act by blocking specific steps in the synthesis of fungal cell membrane components. The broad-spectrum topical antifungal drugs now in use include the imidazoles (e.g. clotrimazole and miconazole), a pyridone-ethanolamine salt, dimethylmorpholines, and the newest class, the allylamines (e.g., naftifine and terbinafine). The topical allylamines have been shown in comparative studies to produce higher cure rates and more rapid responses in dermatophyte infections than many of the older agents.

Fibrin degradation products in growth stimulatory extracts of pathological lesions

We have previously shown that similar patterns of fibrin degradation products (FbDP) by gel electrophoresis and immunoblotting are present in extracts of human atherosclerotic plaques, human and experimental wounds and breast cancers. Such extracts were also shown to stimulate cell proliferation including angiogenesis in the chick chorioallantoic membrane, now shown also for breast cancers. Removal of FbDP from plaque extracts by an anti-fibrinogen affinity column, or by an anti-fragment E column, reduced activity. Human FbDP prepared in vitro were active, but not FgDP. Fibrin fragment E was active, and we also showed that admixture of FbDP with a polyclonal rabbit anti-fibrin E but not anti-fibrin D neutralized activity. However attempts to raise comparable monoclonal blocking antibodies were hindered by species similarities. The response of the Balb/c mouse was predominantly directed at minor D contaminants, in contrast to the Sprague-Dawley rat which responded to fibrin fragment E in our antigen preparation.