Prevention of venous thromboembolism in Wales: results of a survey among general surgeons

OBJECTIVE

To examine the current attitudes towards the prevention of venous thromboembolism among a cohort of surgeons.

DESIGN

A postal survey, comprising a questionnaire covering various aspects of venous thromboembolism prophylaxis was sent to all (n=84) consultant general surgeons in Wales.

RESULTS

Replies were received from 57 surgeons (68%), all of whom routinely used prophylaxis, the most frequent modalities used being heparin (100%) and graded compression stockings (79%). A combination of physical and pharmacological methods was used by over 89% of surgeons, with 60% starting prophylaxis more than two hours before operation. All surgeons continued prophylaxis after surgery, 53% until patients were mobile, 45% until they were discharged, and one surgeon continued prophylaxis for seven days after discharge. The thrombosis risk factors considered most important by surgeons when deciding about prophylaxis were (i) a previous history of venous thromboembolism, (ii) hypercoagulability, and (iii) malignancy.

CONCLUSIONS

This study confirms that Welsh surgeons conform to standard methods, but also highlights some uncertainties that are present in current surgical practice. Those who responded all routinely used prophylaxis, the timing of which was variable. The main risk factors identified when considering prophylaxis were previous history of deep vein thrombosis/pulmonary embolism, hypercoagulability, and the presence of malignancy. Suggestions for future practice are made.

Fixation of distal femoral fractures above total knee arthroplasty utilizing the Less Invasive Stabilization System (L.I.S.S.)

Supracondylar femoral fractures above total knee arthroplasty remain a treatment challenge. Complication rates as high as 30% are associated with both nonoperative and operative treatment. Conventional plate fixation and rigid intramedullary nail fixation has improved the treatment of these fractures. However, problems still exist in the setting of a short distal femoral block and/or significant osteoporosis. Less Invasive Stabilization System (L.I.S.S.) fixation has been utilized for the treatment of supracondylar femoral fractures above total knee arthroplasty. Multiple fixed angle screws give optimal fixation around the femoral component. Advantages appear to include maintenance of distal femoral fixation, low infection, and low need for bone grafting.

The mechanical integrity of healed diaphyseal bone defects grafted with calcium hydroxyapatite/calcium triphosphate ceramic in a new animal model

The need for an animal model to test bone graft materials simulating a weight bearing clinical situation is identified. The concept, design and operative detail of a new model is described. This model involved the creation of a mid-diaphyseal wedge defect in the femur of the adult beagle which separated both cortices, plating with a six-hole dynamic compression plate, and allowed immediate full weight bearing. At six months plates were removed and immediate weight bearing was allowed for an additional six months to sacrifice. The initial animal project utilizing this model to evaluate a hydroxyapatite based synthetic graft material was performed using 12 dogs. In addition to the operative procedure, the retrieval testing in torsion of 12 healed grafted bones and their 12 contralateral unoperated controls is described and evaluated. Results showed no statistically significant difference between the torsional strength of test and control femurs (p less than or equal to 0.05). In addition, the future development of the model is discussed.

Beware of groin pain in the elderly athlete

A62-year-old man, who was a keen amateur swimmer, presented to the orthopaedic department in June 1996 with a 4-month history of lower back pain, which had developed after he had been swimming. Mild tenderness was noted over his left sacroiliac joint, straight leg raising was normal, and resisted movements failed to reproduce his pain. He was advised to alter activity and discharged.

His pain persisted, however, and 10 months later had become localized to his right groin. Further review in the orthopaedic clinic revealed a full range of movement of his hips, but extreme abduction was painful. Plain radiographs of the lumbar spine showed degenerative changes. His pain was attributed to lumbar root irritation, and so he was referred for physiotherapy.

By October 1997, 16 months after initial presentation, there was no real improvement. A soft tissue magnetic resonance imaging scan confirmed spondylosis and degenerate discs, but no actual disc prolapse. As he was still troubled with pain, specifically in the right groin, a general surgical opinion was requested.

Localized tenderness was demonstrated at the deep ring, but no herniation noted. ‘Gilmore's groin’ was suspected, but his advancing age aroused suspicion, therefore other causes needed to be excluded. There was nothing else to find on clinical examination of his abdomen, but rectal examination revealed a hard nodular prostate. A prostate-specific antigen (PSA) test was performed, and this was significantly elevated at 168 ng/ml (normal Ã4 ng/ml). Plain pelvic X-rays were obtained, and reported as sclerotic lesions involving left ischium, right superior pubic ramus and adjacent pubic bone (Figure 1). An isotope bone scan later revealed multiple areas of increased activity consistent with metastatic disease (Figure 2). A subsequent tru-cut biopsy confirmed carcinoma of the prostate.

Activity and expression of the Na(+)/H(+) exchanger in the microvillous plasma membrane of the syncytiotrophoblast in relation to gestation and small for gestational age birth

The effect of gestational age, low birth weight, and umbilical plasma pH on the activity and expression of the Na(+)/H(+) exchanger in the microvillous plasma membrane (MVM) of the placental syncytiotrophoblast was investigated. MVM were isolated from placentas of fetuses delivered in the first and second trimesters and from appropriately grown for gestational age (AGA) and small for gestational age (SGA) babies born at term. Na(+)/H(+) exchange activity (amiloride-sensitive Na(+) uptake) was higher (p<0.05) in second trimester and term AGA MVM versus first trimester MVM (median [range]: 1.80 [1.01-3.03], 1.72 [1.16-3.15] versus 1.48 [0.92-1.66] nmol/mg protein/30s, respectively, n = 6, 12, and 9). As regards exchanger isoforms, Western blotting showed that NHE1 expression did not change across gestation, but NHE2 and NHE3 expression were lower (p<0.01) in the first and second trimesters than in term AGA MVM. There were no differences in Na(+)/H(+) exchanger activity or in NHE1-3 expression in term AGA MVM versus SGA (n = 11) MVM. There was no correlation between exchanger activity and umbilical artery or vein plasma pH, although with a relatively small number of samples (n = 12 and 15, respectively). We conclude that there is differential regulation of the activity and expression of Na(+)/H(+) exchanger isoforms in the MVM over the course of gestation in normal pregnancy; this is not affected in pregnancies resulting in SGA babies at term.

A cytotoxin-producing strain of Vibrio cholerae non-O1, non-O139 as a cause of cholera and bacteremia after consumption of raw clams

We report a case of a cholera-like gastroenteritis subsequent with bacteremia in a healthy man following consumption of raw clams. Although we failed to recover the organism from the patient's stool culture, his blood culture was positive for a non-cholera toxin-producing yet cytotoxin-producing non-O1 and non-O139 Vibrio cholerae.

The effects of growth hormone and insulin-like growth factor on the proliferation rate and morphology of RAW 264.7 macrophages

It is well documented that growth hormone (GH) functions to regulate both cell growth and cell number and is considered the master hormone because it affects almost every cell of the body. Growth hormone stimulates the liver to secrete insulin-like growth factor (IGF-1), which is also capable of binding insulin as well as insulin-like binding receptors on the cell surface. It is possible that GH cellular effects are mediated by IGF-1 rather than GH itself. In this study, RAW 264.7 cells were challenged with a high dose of GH (48 ng/microliter), a low of dose GH (4.8 ng/microliter), a high dose of IGF-1 (26 ng/microliter) or low doses of IGF-1 (6.3 ng/microliter) for 24, 48, 72, and 96 hours. Cell number, cell protein concentration, cell damage, and cellular morphology were measured at each time point and compared to untreated RAW 264.7 cells. The results show significant increases in cell number for cells treated with low doses of GH and IGF-1 at 24 hour phase. Cell proliferative effects were also observed at 48 hours in IGF-1 treated cells. Cellular damage (MDA levels) was not statistically significant for any treated group for the entire duration of the experiment. Most notable differences were observed in cellular morphology for both IGF-1 and GH treated cells. IGF-1 resulted in condensation of the nuclear material as early as 24 hours after treatment.

IN CONCLUSION

(1) RAW 264.7 responded to both IGF-1 and GH equally (viability and proliferation), and (2) morphological changes were observed in all cells treated with both hormones compared to control group. This study indicates that GH hormone could induce its effect directly or indirectly through IGF-1.

Development of sustained delivery system as a novel technique for tissue culture

One of the greatest advances for biomedical research has been the use of tissue culture to study the effects and the mode of action of various organic compounds. However, there are myriad problems associated with the classical approach to pharmaceutical studies in tissue culture, such as contamination, the logistical problems inherent in intermittent dosing, and near-lethal drug doses required to achieve effective physiological doses. This has given impetus to a search for better means of effective delivery routes in a tissue culture setting. The specific objectives of this investigation were: (1) to develop a ceramic delivery system for the novel purpose of releasing sustained levels of the anti-cancer drug combination inositol hexaphosphate (IP6) + inositol (I) in a tissue culture setting; (2) to assess the proliferation rate and viability of HTB 122 Intraductile Breast Cancer (IBC) cells exposed to sustained levels of IP6 + I compared to conventional means of drug delivery (dissolved in media); (3) to evaluate the morphological changes associated with this treatment process. Sterile aseptic techniques were employed during the entire study (72 hours of incubation). Data obtained from this investigation suggests the following: (1) TCPL delivery system can be utilized in the tissue culture setting to deliver IP6 + I in a sustained manner for 72 hours; (2) the use of IP6 + I at the physiological dose did not induce any significant change in the biochemical marker (MDA); (3) morphological evaluation of cells treated with sustained delivery resulted in cellular atrophy, as well as fragmentation, compared to the treatment by conventional means and to the sham group (empty capsule); and (4) regardless of route of administration, treatment with IP6 + I resulted in a decrease in total protein content compared to the sham capsules and control groups. In conclusion, this approach is a novel use of ceramic delivery systems in tissue culture that gives breakthrough information for basic research on limiting and eliminating contamination and the logistical problems associated with intermittent dosing in tissue culture.

Abiotrophia species as a cause of endophthalmitis following cataract extraction

Microorganisms of the genus Abiotrophia, members of the oral flora, are known as important causes of bacterial endocarditis. In this study, we report two individual cases of acute vitreous infection caused by Abiotrophia adiacens and Abiotrophia defectiva approximately a week after cataract extraction. Abiotrophia isolates were recovered by cultivation of vitreous humor on chocolate agar and identified via conventional and API 20 Strep identification systems. An 83-year-old male patient (A) and an 80-year-old female patient (B) demonstrated almost identical symptoms of infectious endophthalmitis manifested as hypopyon and opaque media. The vision of both patients was reduced to detection of hand motion in the left and the right eyes, respectively. An emergency pars plana core vitrectomy was performed, and intraocular antibiotics were administered to each patient, who presented 8 months apart in two different institutions. Patients A and B were treated with an intravitreal injection of vancomycin-amikacin and vancomycin-ceftazidime, respectively, which resulted in complete recovery.

Biochemical and immunochemical evaluation of tissues and synovial fluid from patients undergoing total joint arthroplasty

Cytokines are inflammatory mediators responsible for numerous clinical conditions, and are thought to lead to the resorption of bone. Understanding the nature of the cells producing these factors which control the resorption of bone will ultimately lead to a better understanding of why implants fail or integrate. In this study, synovial tissues and synovial fluids were processed for biochemical as well as histochemical and immunohistochemical determination cytokines responsible for bone resorption. The results from this study showed by both quantitative enzyme linked immunoassay (ELISA) and qualitatively by immunohistology a marked increase (twofold) in interleukin-1 (IL-1), and tumor necrosis factor-beta (TNF beta) in synovial tissues in comparison to control tissues of cartilage, ligament and meniscus. Evaluation of tissues both immunochemically and by Hematoxylin and Eosin demonstrated the presence of fibroblast and cells such as macrophages, and multinucleated giant cells in the synovium that are capable of producing bone resorption. Synovial fluid from primary and revision patients were evaluated for TNF beta and IL-1 were not statistically different. Overall, the results indicate that the inflammatory cells of the synovium are secreting factors which may act to mediate aseptic loosening of implants.

Fibrous capsule formation in response to ultrahigh molecular weight polyethylene treated with peptides that influence adhesion

A wide variety of hard tissue substitute materials for reconstruction have been designed for use in dental and orthopaedic procedures. Most of the literature provides information on the osteocompatibility of these materials, and not on soft tissue compatibility. The bone bonding strength of the materials is relatively high, but there seems to be a lack of bonding properties with soft tissue which results in the formation of fibrous encapsulation. This lack of soft tissue bonding can lead to implant failure. Therefore in order to study how artificial materials may remain in the body for long periods of time and remain functional, it is vital to understand the fibrous tissue encapsulation process. Ultrahigh molecular weight polyethylene coated with RGD, RGE, Poly-L-Lysine, or saline was implanted into Sprague Dawley rats either intraperitoneally or subcutaneously for 12 weeks. Aseptic surgical techniques were followed according to standard laboratory procedures. Blood was collected weekly for the first 8 weeks and at 12 weeks, and analyzed for lactate dehydrogenase activity to assess muscle wasting and compatibility. Lactate dehydrogenase activity was elevated at weeks one and two for groups implanted with materials, in comparison to control unoperated animals. From weeks 3-12, the LDH activity was similar in all groups indicating that there was no adverse response to the implanted material. The implants were harvested at the end of 12 weeks, and the fibrous capsule was screened histologically to determine thickness and cell types at the interface. The results clearly showed that the implants that were placed subcutaneously had a less extensive fibrous and vascular tissue formation, than those implanted intraperitoneally. The results also indicated that the location of the implant intraperitoneally, determined the extent of the fibrous tissue formation. The implanted materials coated with RGD and Poly-L-Lysine had thicker fibrous capsule formation than RGE coated implanted at both the subcutaneous and intraperitoneal sites. The results also suggest that the implant-interface contained fewer inflammatory cells when the implants were placed subcutaneously. The overall results indicate that more than surface charge or coating govern the formation of fibrous tissue in vivo.

The secreted hepatitis B precore antigen can modulate the immune response to the nucleocapsid: a mechanism for persistence

The hepatitis B precore Ag (HBeAg) is a secreted nonparticulate version of the viral nucleocapsid hepatitis B core Ag (HBcAg), and its function is unknown. A proportion of HBeAg-specific Th cells evade deletion/anergy in HBeAg-transgenic (Tg) mice and mediate anti-HBe "autoantibody" (autoAb) production after in vivo activation with the appropriate Th cell peptide. This model system was used to determine how secretory HBeAg may effect deletion of Th cells in the periphery. For this purpose, HBeAg-Tg mice were bred with Fas and Fas ligand (FasL)-defective lpr/lpr and gld/gld mutant mice. Fas-FasL interactions mediate activation-induced apoptosis in the periphery. In HBeAg-Tg/+ mice, high-titrated anti-HBe autoAb was produced that was exclusively composed of the IgG1 isotype (i.e., Th2-like profile). In contrast, HBeAg-Tg/lpr and HBeAg-Tg/gld mice produced significantly less anti-HBe autoAb, and the IgG isotype patterns were broadened to include IgG2a, IgG2b and IgG3 as well as IgG1 (i.e., mixed Th1/Th2-like profile). These results suggest that HBeAg-specific Th1 cells are preferentially depleted by Fas-FasL-mediated interactions. The effect of circulating HBeAg on HBcAg-specific Th1 cells was also examined by transferring HBe/HBcAg-specific Th cells into dual HBeAg- and HBcAg-expressing Tg recipient mice. The presence of serum HBeAg ablated the expected Th1-mediated anti-HBc Ab response and shifted it toward a Th2 phenotype. These results suggest that in the context of a hepatitis B viral infection, circulating HBeAg has the potential to preferentially deplete inflammatory HBeAg- and HBcAg-specific Th1 cells that are necessary for viral clearance, thereby promoting hepatitis B virus persistence.

Role of B cells in antigen presentation of the hepatitis B core

The hepatitis B virus (HBV) nucleocapsid or core antigen (HBcAg) is extremely immunogenic during infection and after immunization. For example, during many chronic infections, HBcAg is the only antigen capable of eliciting an immune response, and nanogram amounts of HBcAg elicit antibody production in mice. Recent structural analysis has revealed a number of characteristics that may help explain this potent immunogenicity. Our analysis of how the HBcAg is presented to the immune system revealed that the HBcAg binds to specific membrane Ig (mIg) antigen receptors on a high frequency of resting, murine B cells sufficiently to induce B7.1 and B7.2 costimulatory molecules. This enables HBcAg-specific B cells from unprimed mice to take up, process, and present HBcAg to naive Th cells in vivo and to T cell hybridomas in vitro approximately 10(5) times more efficiently than classical macrophage or dendritic antigen-presenting cells (APC). These results reveal a structure-function relation for the HBcAg, confirm that B cells can function as primary APC, explain the enhanced immunogenicity of HBcAg, and may have relevance for the induction and/or maintenance of chronic HBV infection.

The immune microenvironment of human fracture/soft-tissue hematomas and its relationship to systemic immunity

The immune environment of human soft-tissue injury is unstudied. We studied fracture soft-tissue hematomas (FxSTH) in 56 patients with high-energy bony fractures. FxSTH serum and mononuclear cells (MNC) as well as fracture patient plasma and blood MNC were studied. Twenty healthy controls donated plasma and MNC. Soluble tumor necrosis factor (TNF)-alpha, interleukin (IL-1 beta, IL-2, 6, 8, 10, 12, and interferon-gamma were studied by enzyme linked immunosorbent assay. Cells were studied by flow cytometry after cell-membrane stains for CD-14, TNF-alpha (mTNF), and human leukocyte antigen-DR, or intracellular stains for TNF (icTNF) and IL-10. Thirty-six patients with Injury Severity Score < 15 were analyzed further to evaluate the effects of isolated fracture on systemic immunity. Cytokines were rarely detectable in control plasma. TNF-alpha, IL-1 beta, IL-2, and interferon-gamma were rarely found in FxSTH serum or fracture patient plasma. All FxSTH sera were rich in IL-6, peaking before 48 hours (12,538 +/- 4,153 vs. 3,494 +/- 909 pg/mL, p = 0.02, U test). In Injury Severity Score < 15, IL-6 was not detectable in most early fracture patient plasma, but rose after 48 hours (p = 0.028). FxSTH serum IL-8 peaked after 48 hours (440 +/- 289 vs. 4,542 +/- 1,219 pg/mL, p = 0.006) and circulating IL-8 appeared after 72 hours. IL-6 and IL-8 showed gradients from FxSTH serum to paired PtS (p < 0.05, Wilcoxon). IL-10 was abundant (884 +/- 229 pg/mL) in FxSTH serum < 24 hours old. FxSTH serum IL-12 peaked late (3,323 +/- 799 pg/mL, day 4-7) then fell (p < 0.001, analysis of variance). Only IL-12 was higher in fracture patient plasma (1,279 +/- 602 pg/mL) than FxSTH serum (591 +/- 327 pg/mL) during the first 48 hours (p = 0.032, U test). On flow cytometry, control monocytes expressed 201 +/- 31 mTNF sites/cell, but icTNF was absent. mTNF was up-regulated after injury more in FxSTH monocytes (3,202 +/- 870 sites/cell) than peripheral blood monocytes (584 +/- 186 sites/cell) (p < 0.05 vs. peripheral blood monocytes by Wilcoxon, p < 0.001 vs. control monocytes by U test). Intracellular IL-10 was abundant in all MNC, but varied widely after injury. Fracture and peripheral blood monocytes expressed far less human leukocyte antigen-DR than control monocytes. Fractures create an inflammatory local environment. Proximal mediators are cell-associated and relatively confined to the wound, but soluble IL-6, IL-8, and IL-10 are abundant and probably exported. Systemic MNC have complex responses to local injuries. These may reflect the combined impact of multiple soluble cytokines initially generated within the wound. FxSTH appear to be a potentially important source of immunomodulatory cytokines in trauma.

The hepatitis B virus core and e antigens elicit different Th cell subsets: antigen structure can affect Th cell phenotype

Secretion of the hepatitis B virus (HBV) e antigen (HBeAg) has been conserved throughout the evolution of hepadnaviruses. However, the function of this secreted form of the viral nucleoprotein remains enigmatic. It has been suggested that HBeAg functions as an immunomodulator. We therefore examined the possibility that the two structural forms of the viral nucleoprotein, the particulate HBV core (HBcAg) and the nonparticulate HBeAg, may preferentially elicit different T helper (Th) cell subsets. For this purpose, mice were immunized with recombinant HBcAg and HBeAg in the presence and absence of adjuvants, and the immunoglobulin G (IgG) isotype profiles of anti-HBc and anti-HBe antibodies were determined. Second, in vitro cytokine production by HBcAg- and HBeAg-primed Th cells was measured. The immunogenicity of HBcAg, in contrast to that of HBeAg, did not require the use of adjuvants. Furthermore, HBcAg elicited primarily IgG2a and IgG2b anti-HBc antibodies, with a low level of IgG3, and no IgG1 anti-HBc antibodies. In contrast, the anti-HBe antibody response was dominated by the IgG1 isotype; low levels of IgG2a or IgG2b anti-HBe antibodies and no IgG3 anti-HBe antibodies were produced. Cytokine production by HBcAg- and HBeAg-primed Th cells was consistent with the IgG isotype profiles. HBcAg-primed Th cells efficiently produced interleukin-2 (IL-2) and gamma interferon (IFN-gamma) and low levels of IL-4. Conversely, efficient IL-4 production and lesser amounts of IFN-gamma were elicited by HBeAg immunization. The results indicate that HBcAg preferentially, but not exclusively, elicits Th1-like cells and that HBeAg preferentially, but not exclusively, elicits Th0 or Th2-like cells. Because HBcAg and the HBeAg are cross-reactive in terms of Th cell recognition, these findings demonstrate that Th cells with the same specificity can develop into different Th subsets based on the structural form of the immunogen. These results may have relevance to chronic HBV infection. Circulating HBeAg may downregulate antiviral clearance mechanisms by virtue of eliciting anti-inflammatory Th2-like cytokine production. Last, the influence of antigen structure on Th cell phenotype was not absolute and could be modulated by in vivo cytokine treatment. For example, IFN-alpha treatment inhibited HBeAg-specific Th2-mediated antibody production and altered the IgG anti-HBe isotype profile toward the Th1 phenotype.

Production of interleukin-10 in human fracture soft-tissue hematomas

Clinical trauma suppresses immunity and experimental wound fluids have been shown to be immunosuppressive. To ascertain whether human wounds contain immunosuppressive cytokines, we assayed serum from fracture/soft-tissue hematomas (FSTH) of 22 patients for interleukin (IL)-10, transforming growth factor (TGF)-beta 1, and IL-4. Results were correlated to concurrent plasma cytokine concentrations in the same patients and in volunteer plasma. IL-10 was present in high concentration (1376 +/- 539 pg/mL) in all (7/7) FSTH < 24 h old. In FSTH > 24 h old, IL-10 was found intermittently and at lower levels (239 +/- 106 pg/mL, p = .011 vs. FSTH < 24 h old). IL-10 was rarely detectable in fracture patient plasma and never detectable (< 20 pg/mL) in normal plasma. No significant variations of IL-4 or total TGF-beta 1 were found in FSTH or plasma. FSTH are significant potential sources of IL-10 activity in trauma patients, which may be overlooked when only plasma is assayed. The potential for a relationship between cytokines found locally at sites of injury and clinical immune modulation in trauma requires further study.

Differentiation of rare leukodystrophies by post-mortem morphological and biochemical studies: female adrenoleukodystrophy-like disease and late-onset Krabbe disease

Two 6-year-old patients with clinical signs of leukodystrophy had no nosological diagnoses in vivo. Neuropathological studies revealed scavenger cells to be clustered in perivascular regions of the demyelinated brains. Histochemical and ultrastructural details of the non-metachromatic storage macrophages suggested lipid storage and prompted a biochemical analysis of cerebral tissue. The detection of increased amounts of very long chain fatty acids in the cholesterol ester fraction from formalin tissue in one patient was consistent with a diagnosis of an adrenoleukodystrophy-like condition, while the marked reduction in beta-galactocerebrosidase activity in a frozen brain sample of the second patient indicate Krabbe disease. The diagnostic potential of post-mortem studies in rare leukodystrophies is addressed.

Cleavage and deprotection of peptide resins using chloro- and bromotrialkylsilanes

The cleavage of a peptide resin attached to a phenylacetomidomethyl (PAM) resin was investigated using bromotrimethylsilane (TMSBr) with thioanisole in trifluoroacetic acid (TFA), and by chlorotrimethylsilane (TMSCl) in the same reagents with lithium bromide. Both TMSBr and TMSCl cleaved the peptide from the resin, but TMSCl required elevated temperature (50 degrees C) to effect the cleavage. Procedures were investigated for the deprotection and cleavage of either N(g)-tosyl (Tos)- or mesitylenesulfonyl (MTS)-arginine residues attached to 4-methylbenzylhydrylamine (MBHA) resin, and of a peptide containing an MTS-arginine residue attached to MBHA resin, using either TMSCl or TMSBr as cleavage reagents. The MTS group is cleanly removed from arginine using TMSBr with thioanisole in TFA and by TMSCl in the same reagents with lithium bromide.

Interleukin 12 suppresses autoantibody production by reversing helper T-cell phenotype in hepatitis B e antigen transgenic mice

Helper T (Th) cells are classified as Th1 or Th2 cells by virtue of cytokine secretion and function as mediators of cellular or humoral immunity, respectively. Cytokines also regulate the differentiation of Th cells. For example, interleukin (IL)-12 promotes Th1 and suppresses Th2 cell development, suggesting that IL-12 may be useful therapeutically in Th2-mediated autoimmune and allergic disorders. Therefore, the effect of systemic IL-12 treatment on in vivo autoantibody synthesis in hepatitis B e antigen (HBeAg)-expressing transgenic mice, which is dependent on self-reactive Th2 cells, was examined. Low-dose IL-12 significantly inhibited autoantibody production by shifting the Th2-mediated response toward Th1 predominance. Additionally, previous studies suggest that a predominance of HBeAg-specific Th2-type cells may contribute to chronicity in hepatitis B virus infection. Therefore, IL-12 may also prove beneficial in modulating the HBeAg-specific Th response to favor viral clearance in chronic hepatitis B virus infection.

Characterization of self-reactive T cells that evade tolerance in hepatitis B e antigen transgenic mice

Previous studies of hepatitis B e antigen (HBeAg)-expressing transgenic (Tg31e) mice have indicated that the degree of T cell tolerance was epitope specific. For example, T cells specific for residues 120-131 of HBeAg are profoundly tolerant, whereas a proportion of T cells specific for residues 129-140 escape tolerance induction in B10. S x B10-Tg31e mice. To understand the basis for differential tolerance towards two T cell sites on the same self antigen, we characterized T cell recognition of HBeAg by primary T cells and T cell hybridomas derived from HBeAg-Tg and non-Tg mice. The self-reactive T cells surviving in B10-Tg31e mice exhibited a unique fine specificity, albeit still focussed on HBeAg residues 129-140, which could be distinguished from the HBeAg-specific T cell repertoire in non-Tg B10 mice. Further, self-reactive T cells were comprised predominantly of Th2-type cells that preferentially evaded tolerance induction as compared to their Th1 counterparts. Because HBeAg may act as a tolerogen during the vertical transmission of chronic hepatitis B virus (HBV) infection, these results suggest that a predominance of HBeAg-specific Th2 cells expressing a limited repertoire may influence the initiation or the maintenance of the HBV chronic carrier state.

The hepatitis nucleocapsid as a vaccine carrier moiety

The "carrier effect," defined as the provision of T cell recognition sites physically linked to B cell epitopes in order to provide Th cell function for antibody synthesis, is well known. Peptides, proteins, and more recently particulate protein antigens have been used for this purpose. The hepatitis B core antigen represents a highly immunogenic antigen in humans as well as in experimental animal models. Studies in mice have provided insight into this enhanced immunogenicity. For example, HBcAg directly activates B cells (i.e., T cell independence), HBcAg elicits strong T cell responses, and HBcAg is efficiently processed and presented by antigen presenting cells (APCs). These characteristics suggested that HBcAg may be an ideal carrier moiety for B cell epitopes requiring additional Th cell function. Therefore, a number of HBV and non-HBV B cell epitopes have been chemically linked or fused by recombinant methods to HBcAg as a method to increase immunogenicity with significant success. We have designed bacterial expression vectors that allow insertion of heterologous B cell epitopes at various positions within HBcAg particles and permit efficient purification of hybrid HBcAg particles. Studies of positional effects have demonstrated that an internal insertion into a dominant HBcAg-specific B cell site represents a superior location for enhanced antibody production. Immunogenicity studies have been extended to protection against experimental challenge in several systems. For example, a malaria CS repeat sequence derived from P. berghei was inserted into HBcAg at the internal site, and purified hybrid HBcAg/CS particles were highly immunogenic and protected 100% of experimentally challenged BALB/c mice. This system has also been exploited for purposes of oral vaccination by expressing genes coding for hybrid HBcAg particles in live, avirulent vaccine strains of Salmonella species.

Preferential recognition of hepatitis B nucleocapsid antigens by Th1 or Th2 cells is epitope and major histocompatibility complex dependent

Regulatory T-helper (Th) cells have been categorized into two functional subsets, Th1 and Th2 cells, which produce distinct lymphokines. In general, Th1 cells mediate cellular immune responses and Th2 cells mediate humoral immunity. Recent serological studies suggest that the Th1-Th2 balance may be relevant in acute and chronic hepatitis B virus (HBV) infections. The purpose of this study was to determine the potential of the nucleocapsid antigens (Ags) (hepatitis B core and e Ags [HBc/eAg]) of HBV to preferentially elicit either a Th1 or a Th2 dominant response. For this purpose, H-2 congenic B10.S and B10 mice were immunized with HBc/eAg, and Ag-specific T-cell proliferative responses, T-cell helper function, and T-cell cytokine production were analyzed. The results indicated that B10.S mice preferentially develop a Th1-like response whereas B10 mice preferentially develop a Th2-like response after immunization with HBc/eAg. Furthermore, the preferential Th1 and Th2 response patterns were reproduced when 12-residue peptides representing the dominant HBc/eAg-specific T-cell sites for B10.S (peptide 120-131) and B10 (peptide 129-140) mice were used as immunogens. Therefore, the combination of the T-cell site recognized and the major histocompatibility complex restricting element can in large part determine the Th phenotype of the HBc/eAg-specific T-cell response. Other factors that influenced Th phenotype were the presence of exogenous cytokines, Ag structure, and tissue distribution.

Pitfalls in the prenatal diagnosis of peroxisomal beta-oxidation defects by chorionic villus sampling

Variability in the level of expression of very long chain fatty acids (VLCFAs) is documented in cultured chorionic villus (CV) cells derived from two fetuses, one at risk for an unusual peroxisomal fatty acid beta-oxidation defect, and the other at risk for the X-linked form of adrenoleucodystrophy (ALD). Cells from early subcultures of chorionic cells from both cases gave normal values for VLCFA ratios. The results for the fetus at risk for the beta-oxidation defect were interpreted to indicate that the fetus was not affected; however, at birth, the infant was clinically and biochemically affected. In the case of the fetus at risk for X-linked ALD, although VLCFAs were normal in subculture 1, the levels of these fatty acids increased dramatically in subculture 3, suggesting an abnormal fetus. Termination of the pregnancy and subsequent biochemical and morphological follow-up confirmed that the fetus was indeed affected by ALD.

Soluble CTLA-4 can suppress autoantibody production and elicit long term unresponsiveness in a novel transgenic model

Activation of Ag-specific T cells often requires costimulatory signals in addition to the primary signal mediated through the TCR. The CD28-B7 interaction provides one important costimulatory signal. Previous studies have shown that a soluble CD28 homologue, CTLA4lg, binds B7 with high affinity and can inhibit CD28-B7-mediated costimulation in vitro and in vivo. In this study we examined the ability of soluble human CTLA4lg to inhibit autoantibody production in vivo. For this purpose we used a novel transgenic (Tg) model of autoantibody production. Hepatitis B eAg-expressing Tg mice can be induced to produce autoantibody to the circulating autoantigen (HBeAg) by the injection of a T cell recognition site that fails to elicit T cell tolerance in these mice. Autoimmunity in this model is quantitative because serum autoantibody and autoantigen concentration are inversely correlated and easily measurable by ELISA. In this system a single regimen of CTLA4lg treatment significantly suppressed primary autoantibody production and variably led to long term unresponsiveness. Furthermore, in vivo treatment with CTLA4lg inhibited both T cell activation and T cell-B cell interactions.

Soluble CTLA-4 can suppress autoantibody production and elicit long term unresponsiveness in a novel transgenic model

Activation of Ag-specific T cells often requires costimulatory signals in addition to the primary signal mediated through the TCR. The CD28-B7 interaction provides one important costimulatory signal. Previous studies have shown that a soluble CD28 homologue, CTLA4lg, binds B7 with high affinity and can inhibit CD28-B7-mediated costimulation in vitro and in vivo. In this study we examined the ability of soluble human CTLA4lg to inhibit autoantibody production in vivo. For this purpose we used a novel transgenic (Tg) model of autoantibody production. Hepatitis B eAg-expressing Tg mice can be induced to produce autoantibody to the circulating autoantigen (HBeAg) by the injection of a T cell recognition site that fails to elicit T cell tolerance in these mice. Autoimmunity in this model is quantitative because serum autoantibody and autoantigen concentration are inversely correlated and easily measurable by ELISA. In this system a single regimen of CTLA4lg treatment significantly suppressed primary autoantibody production and variably led to long term unresponsiveness. Furthermore, in vivo treatment with CTLA4lg inhibited both T cell activation and T cell-B cell interactions.

Extrathymic expression of the intracellular hepatitis B core antigen results in T cell tolerance in transgenic mice

We previously developed a transgenic (Tg) murine lineage (B10.S-Tg31e), which secretes the hepatitis B e Ag (HBeAg) into the serum at a concentration of 10 ng/ml. This serum concentration was sufficient to render B10.S-Tg31e mice functionally tolerant at the T cell but not B cell level. To determine the tolerogenic potential of an intracellular form of this Ag, namely the hepatitis B core Ag (HBcAg), expressed outside the thymus, the B10.S-Tg10c lineage was developed. In B10.S-Tg10c mice the HBcAg is expressed as an intracellular "self"-Ag predominantly in the liver, and cannot be detected in the serum, the thymus or in nonthymic lymphoid tissue. Despite the liver-specific and intracellular location of this transgenic self-protein, B10-STg10c mice demonstrate a significant degree of HBcAg-specific T cell tolerance at the level of T cell proliferation. Similarly, in vivo anti-HBc antibody production after HBcAg immunization is significantly reduced as compared with non-Tg littermate controls. No spontaneous anti-HBc antibody is produced in B10.S-Tg10c mice, however, adoptive transfer of HBcAg-specific T cells from non-Tg B10.S mice elicits anti-HBc specific "autoantibody" production. Interestingly, antibodies with specificity for the HBeAg as well as the HBcAg are produced. Antibody production in B10.S-Tg10c mice adoptively transferred with T cells indicates that sufficient native HBcAg can gain access to the extracellular compartment to engage HBcAg-specific B cells that are clearly not tolerant in this model. No liver injury was observed as a consequence of HBcAg expression, even in B10.S-Tg10c mice adoptively transferred with HBcAg-specific T cells. Unless HBcAg is unique in this regard, these results suggest that organ-specific, intracellular self-Ag may be released during normal cell turnover in sufficient concentrations to elicit systemic T cell tolerance. B10.S-Tg10c mice also serve as an immunologic model system for chronic infection with the HBeAg-negative mutant of the hepatitis B virus.

Extrathymic expression of the intracellular hepatitis B core antigen results in T cell tolerance in transgenic mice

We previously developed a transgenic (Tg) murine lineage (B10.S-Tg31e), which secretes the hepatitis B e Ag (HBeAg) into the serum at a concentration of 10 ng/ml. This serum concentration was sufficient to render B10.S-Tg31e mice functionally tolerant at the T cell but not B cell level. To determine the tolerogenic potential of an intracellular form of this Ag, namely the hepatitis B core Ag (HBcAg), expressed outside the thymus, the B10.S-Tg10c lineage was developed. In B10.S-Tg10c mice the HBcAg is expressed as an intracellular "self"-Ag predominantly in the liver, and cannot be detected in the serum, the thymus or in nonthymic lymphoid tissue. Despite the liver-specific and intracellular location of this transgenic self-protein, B10-STg10c mice demonstrate a significant degree of HBcAg-specific T cell tolerance at the level of T cell proliferation. Similarly, in vivo anti-HBc antibody production after HBcAg immunization is significantly reduced as compared with non-Tg littermate controls. No spontaneous anti-HBc antibody is produced in B10.S-Tg10c mice, however, adoptive transfer of HBcAg-specific T cells from non-Tg B10.S mice elicits anti-HBc specific "autoantibody" production. Interestingly, antibodies with specificity for the HBeAg as well as the HBcAg are produced. Antibody production in B10.S-Tg10c mice adoptively transferred with T cells indicates that sufficient native HBcAg can gain access to the extracellular compartment to engage HBcAg-specific B cells that are clearly not tolerant in this model. No liver injury was observed as a consequence of HBcAg expression, even in B10.S-Tg10c mice adoptively transferred with HBcAg-specific T cells. Unless HBcAg is unique in this regard, these results suggest that organ-specific, intracellular self-Ag may be released during normal cell turnover in sufficient concentrations to elicit systemic T cell tolerance. B10.S-Tg10c mice also serve as an immunologic model system for chronic infection with the HBeAg-negative mutant of the hepatitis B virus.

Torsional properties of healed canine diaphyseal defects grafted with a fibrillar collagen and hydroxyapatite/tricalcium phosphate composite

The need for alternatives to autogenous bone grafts is widely recognized. This study compared the torsional strength of canine femora 1 year after grafting with one of three forms of a collagen/hydroxyapatite/tricalcium phosphate bone grafting material (COLLAGRAFTTM), autogenous bone, or no graft. The groups were compared to each other and to the unoperated contralateral femora. Results of torsional testing were evaluated for torsional strength, torsional displacement, total energy to fracture and White fracture mode. Data analysis showed lower torsional strength of the operated vs. unoperated femora with the exception of morsellized COLLAGRAFTTM material, which had higher strength. However, the only difference in the operated groups was that the morsellized COLLAGRAFTTM had greater strength than several groups including the autogenous bone group. There was no difference found in angular displacement between any of the groups. However, there was a difference in the energy to fracture in both strip forms of the COLLAGRAFTTM. The final conclusion is that in this model, grafting with COLLAGRAFTTM provided torsional properties at one year postoperatively at least equivalent to autogenous bone.

Establishment of a normal range of morphometric values for peroxisomes in paediatric liver

The size and number of hepatic peroxisomes was investigated in 16 control paediatric liver biopsies from patients ranging in age from 3 months to 18 years one fetal liver specimen and one paediatric autopsy liver. The area, diameter, volume density (Vv), numerical density (Nv) and surface density (Sv) of the peroxisomes was recorded using randomly selected electron micrographs. The mean diameter of peroxisomes in control paediatric liver was 0.56 microns, the mean Vv was 1.67%, the mean Nv was 0.125 per micron+3 and the mean Sv was 0.161 per micron. No correlation was found between the size and number of hepatic peroxisomes and the age or sex of the patient. Peroxisomes in the fetal liver were smaller than those in biopsy tissue and had a mean diameter of 0.42 micron. Peroxisomes were identified in autopsy tissue and were enlarged with a mean diameter of 0.75 micron, most probably due to post-mortem swelling. A range of morphometric values in paediatric liver has now been established.

Morphometry of peroxisomes and immunolocalization of peroxisomal proteins in the liver of patients with generalised peroxisomal disorders

Hepatic peroxisomes were studied by morphometric and immunocytochemical techniques in control patients and in four Zellweger syndrome patients, two infantile Refsum's (IRD) patients, one neonatal adrenoleukodystrophy (NALD) patient, and three patients with peroxisomal disorders (PD) which do not fit any currently recognised classification, but have disorders involving a defect in peroxisomal biogenesis. Peroxisomes which were ultrastructurally abnormal and greatly reduced in size and/or number were found in two of the Zellweger syndrome patients, and the NALD and IRD patients. There was variation in their numerical density ranging from none at all in two of the Zellweger syndrome patients to normal numbers in the IRD patients. In most patients there was a decrease in the immunolabelling of catalase over the peroxisomes. In the Zellweger syndrome and NALD patients, the small, abnormal peroxisomes did not label for any of the beta-oxidation proteins. The IRD patients and the PD patients however, were heterogeneous with respect to beta-oxidation labelling. The ultrastructural heterogeneity of peroxisomes in these peroxisomal disorders patients indicates there may be genotypic differences between the major groups and also within each group. The common factor in all the patients in this study where peroxisomes were present was the presence in the hepatic peroxisomes of an electron dense centre which did not label immunocytochemically for catalase or the beta-oxidation enzymes. This electron dense centre may indicate a structural abnormality in the peroxisomes in these patients.

Comminuted fractures of the proximal radius and ulna

Forty-three comminuted fractures of the proximal radius and ulna in 34 patients were treated with operative stabilization using AO/ASIF techniques. The patients were divided into three groups, according to the type of injury: Group I, isolated comminuted fractures of the olecranon (18 patients); Group II, isolated fractures of the radial head (eight patients); Group III, combined olecranon and radial head fractures (eight patients). All fractures were followed until union. The average follow-up period was 18 months (range, 12-48 months). At the time of this review, the average limits of elbow motion were 20 degrees extension, 118 degrees flexion, 65 degrees pronation, and 62 degrees supination. Two patients were unable to return for follow-up examination. Using the functional classification of Broberg and Morrey, results were rated as excellent in nine cases, good in 15, fair in five, and poor in three. The complication rate in this series was 19%: Two patients developed nonunion, and one patient lost reduction during rehabilitation. All of these patients required reoperation, with eventual satisfactory outcome. Three patients developed heterotopic ossification, two of which were minor and one of which produced ankylosis of the elbow joint. Each of these patients had delayed (more than 72 hours postinjury) stabilization. A functional elbow was achieved in 29 of the 32 patients who returned for follow-up examination. Operative stabilization of comminuted fractures of the proximal radius and ulna provides a stable painless joint with a functional, but not full, range of motion.

Structure of hepatitis B virus core and e-antigen. A single precore amino acid prevents nucleocapsid assembly

The hepatitis B virus core gene codes for two polypeptides: the core protein, which assembles to form particles (HBcAg), and the secreted precore protein (HBeAg). Expression vectors directing the synthesis in Escherichia coli of a recombinant HBeAg corresponding in sequence to serum-derived HBeAg encompassing the 10 precore amino acids remaining after cleavage of the precursor and residues 1-149 of HBcAg (PC-HBeAg) were constructed. Recombinant PC-HBeAg, HBcAg, and C-terminally truncated HBcAg were isolated from E. coli and analyzed by sucrose velocity sedimentation, electron microscopy, anti-HBc/e specific monoclonal antibody analysis, and for immunogenicity. HBcAg and truncated HBcAg formed 27-nm particles and displayed HBc antigenicity. In contrast, PC-HBeAg was nonparticulate and did not band in sucrose gradients. PC-HBeAg was recognized efficiently by HBeAg-specific antibodies and displayed little HBc antigenicity. Immunogenicity studies including T and B cell recognition confirmed that PC-HBeAg demonstrates HBe antigenicity. The presence of the 10 precore amino acids therefore prevented particle formation. To analyze which precore amino acids might be responsible for the prevention of particle formation a cysteine to glutamine substitution at amino acid position -7 was introduced into PC-HBeAg (-7C-->Q)PC-HBeAg. This single amino acid change at position -7 restored particle formation and HBc antigenicity. The evolutionarily conserved cysteine at position -7 thus appears responsible for the prevention of particle assembly in the HBeAg biosynthesis pathway.

Ultrastructure and immunocytochemistry of hepatic peroxisomes in rhizomelic chondrodysplasia punctata

Peroxisomes were studied in the liver of two rhizomelic chondrodysplasia punctata patients using electron microscopy and catalase cytochemistry. Immunoelectron microscopy was carried out on the liver of one of these patients using antibodies to catalase, acyl-CoA oxidase, bifunctional protein, 3-ketoacyl-CoA thiolase and a 68 kDa peroxisomal membrane protein, in conjunction with protein-A colloidal gold. Moderately to markedly enlarged, flocculent peroxisomes were found in both patients. In one patient they were very heterogeneous with regard to the number per hepatocyte. The peroxisomes had very low levels of catalase as indicated by cytochemistry and immunocytochemistry. The three beta-oxidation enzymes were localised normally within the peroxisomes. The 68 kDa membrane protein was localised to the peroxisomal membranes. Some extra membrane loops were also identified using this antibody.

Cleavage and deprotection of peptides on MBHA-resin with hydrogen bromide

Dilute hydrogen bromide in trifluoroacetic acid containing pentamethylbenzene and thioanisole was used in the cleavage and deprotection of peptides on MBHA-resin. Particular attention was paid to potential applicability of the method to kilogram scale synthesis of thymosin alpha 1. In the HPLC purification of the peptides, acetonitrile was replaced by relatively nontoxic isopropanol. The change should be economically and environmentally very attractive.

The position of heterologous epitopes inserted in hepatitis B virus core particles determines their immunogenicity

The nucleocapsid (HBcAg) of the hepatitis B virus (HBV) has been suggested as a carrier moiety for vaccine purposes. We investigated the influence of the position of the inserted epitope within hybrid HBcAg particles on antigenicity and immunogenicity. For this purpose, genes coding for neutralizing epitopes of the pre-S region of the HBV envelope proteins were inserted at the amino terminus, the amino terminus through a precore linker sequence, the truncated carboxy terminus, or an internal site of HBcAg by genetic engineering and were expressed in Escherichia coli. All purified hybrid HBc/pre-S polyproteins were particulate. Amino- and carboxy-terminal-modified hybrid HBc particles retained HBcAg antigenicity and immunogenicity. In contrast, insertion of a pre-S(1) sequence between HBcAg residues 75 and 83 abrogated recognition of HBcAg by 5 of 6 anti-HBc monoclonal antibodies and diminished recognition by human polyclonal anti-HBc. Predictably, HBcAg-specific immunogenicity was also reduced. With respect to the inserted epitopes, a pre-S(1) epitope linked to the amino terminus of HBcAg was not surface accessible and not immunogenic. A pre-S(1) epitope fused to the amino terminus through a precore linker sequence was surface accessible and highly immunogenic. A carboxy-terminal-fused pre-S(2) sequence was also surface accessible but weakly immunogenic. Insertion of a pre-S(1) epitope at the internal site resulted in the most efficient anti-pre-S(1) antibody response. Furthermore, immunization with hybrid HBc/pre-S particles exclusively primed T-helper cells specific for HBcAg and not the inserted epitope. These results indicate that the position of the inserted B-cell epitope within HBcAg is critical to its immunogenicity.

Identification of a catalase-negative sub-population of peroxisomes induced in mouse liver by clofibrate

The peroxisomal compartment in mouse liver was investigated using rate sedimentation of liver subfractions on sucrose density gradients. Treatment of mice with clofibrate, a hypolipidemic agent and peroxisome proliferator, resulted in the formation of small particles which were devoid of catalase and urate oxidase, but which were identified as peroxisomal on the basis of content of the clofibrate-induced peroxisomal beta-oxidation enzymes (fatty acyl-CoA oxidase, hydratase/dehydrogenase bifunctional protein, and thiolase) and the 68 kDa peroxisomal integral membrane protein. Immunoelectron microscopy confirmed the membrane-bound organellar nature and enzyme composition of these particles. These particles were absent in normal mice, and were increased to a maximal level within 2 days of clofibrate treatment. These data have been taken as indicative of a role of these particles in the mechanism of drug-induced peroxisome proliferation.

Autoantibody production in hepatitis B e antigen transgenic mice elicited with a self T-cell peptide and inhibited with nonself peptides

Studies in hepatitis B e antigen (HBeAg)-expressing transgenic mice indicate that self tolerance to two T-cell determinants on the same transgenic self molecule can differ markedly. The dominant T-cell site on HBeAg is tolerogenic, whereas a proportion of T cells recognizing a second T-cell site evade tolerance induction, persist in the periphery, and can be activated in vivo by a single injection of a 12-residue T-cell self peptide. The self-reactive T cells mediate in vivo autoantibody production sufficient to neutralize detection of the autoantigen in serum. Furthermore, autoantibody production can be inhibited by nonself peptides that compete with the self peptide for binding to major histocompatibility complex molecules. This model illustrates that T cells specific for an immunogenic T-cell site on a nonsequestered autoantigen can escape tolerance induction and, more importantly, can mediate autoreactivity in vivo. Furthermore, these results suggest that synthetic T-cell sites may be useful as immunotherapeutic agents for the purpose of circumventing nonresponse to HBeAg during persistent hepatitis B virus infection.

Importance of subtype in the immune response to the pre-S(2) region of the hepatitis B surface antigen. II. Synthetic Pre-S(2) immunogen

One purpose of this study was to examine the influence of viral subtype on in vivo antibody production to the pre-S(2) region of the hepatitis B surface Ag. Immunization with hepatitis B surface Ag particles containing the pre-S(2) region of the d or y subtypes identified the B10.M (H-2f) strain as an antibody nonresponder to the pre-S(2) and S regions after immunization with the y subtype, but as an antibody responder to the pre-S(2) and S regions after immunization with the d subtype. Both the S region and pre-S(2) region-specific antibody responses emanated from pre-S(2)/d-specific Th cell function because B10.M mice are T cell nonresponsive to the S region of both subtypes. Although responder/nonresponder status of the B10.M strain was dependent on the pre-S(2) subtype used for immunization, the anti-pre-S(2) antibody produced was totally cross-reactive on both subtypes. This is consistent with the conserved nature of the dominant pre-S(2) antibody-binding site and the highly polymorphic nature of the pre-S(2) sequence that represents the focus of T cell recognition. These data suggest that, to fully benefit from the inclusion of pre-S(2) region sequences, third generation hepatitis B virus vaccines should contain both the d and y subtype sequences of the pre-S(2) region to increase the frequency of pre-S(2) and S-specific antibody responses and to insure Th cell memory relevant to both viral subtypes. A second purpose of this study was to "design" a synthetic pre-S(2) immunogen based on combining the dominant B and T cell recognition sites into a single peptide. A composite peptide consisting of the dominant T cell recognition sequence p151-174 positioned N-terminal to the dominant B cell site p133-143 (i.e., p151-174(133-143] yielded an effective pre-S(2) synthetic immunogen. Interestingly, the orientation of the T and B cell determinants and the context of the T cell site within the larger composite peptide influenced both antibody fine specificity and T cell fine specificity.

Importance of subtype in the immune response to the pre-S(2) region of the hepatitis B surface antigen. I. T cell fine specificity

Previous studies of murine T cell recognition of the pre-S(2) region of the hepatitis B surface Ag (HBsAg) identified high (H-2b,d,q), intermediate (H-2s,k), and low to nonresponder (H-2f) haplotypes. However, these studies utilized the y subtype of HBsAg. The purpose of this study was to examine the influence of viral subtype on T cell recognition of the pre-S(2) region and to identify specific T cell recognition sites in a panel of H-2 congenic strains. Immunization with pre-S(2) containing HBsAg particles of the d and y subtypes indicated that T cell recognition of the pre-S(2) region is predominantly subtype-specific in murine strains of eight different H-2 haplotypes. Furthermore, the B10.M strain (H-2f) classified as a T cell nonresponder to the y subtype of the pre-S(2) region responds efficiently to the d subtype, indicating that pre-S(2) responder status can be subtype-dependent as well as subtype-specific. Studies using a truncated pre-S(2) polypeptide and synthetic peptides illustrated that the C-terminal sequence (p148-174) of the pre-S(2) region is the dominant focus of T cell recognition in multiple murine strains. Specifically, 17 distinct T cell recognition sites were defined within the C-terminal half of the pre-S(2) region. The fine specificity of T cell recognition of the pre-S(2) region was dependent on the H-2 haplotype of the responding strain. T cell recognition of all 17 sites was subtype specific, which is consistent with the fact that the C-terminal sequence is highly polymorphic between the d and y subtypes of the pre-S(2) region. Lastly, it was shown that the ability of synthetic peptides to elicit T cells cross-reactive with the native pre-S(2) region was variable and depended on the nature of the immunizing peptide. The pre-S(2)-containing HBsAg vaccines currently in clinical trials are composed of ra single subtype, either d or y. The results of this study suggest that both subtypes should be incorporated to increase the frequency of T cell responders to the pre-S(2) region, and to insure Th cell memory relevant to infection with hepatitis B virus of either the d or y subtypes.

Importance of subtype in the immune response to the pre-S(2) region of the hepatitis B surface antigen. II. Synthetic Pre-S(2) immunogen

One purpose of this study was to examine the influence of viral subtype on in vivo antibody production to the pre-S(2) region of the hepatitis B surface Ag. Immunization with hepatitis B surface Ag particles containing the pre-S(2) region of the d or y subtypes identified the B10.M (H-2f) strain as an antibody nonresponder to the pre-S(2) and S regions after immunization with the y subtype, but as an antibody responder to the pre-S(2) and S regions after immunization with the d subtype. Both the S region and pre-S(2) region-specific antibody responses emanated from pre-S(2)/d-specific Th cell function because B10.M mice are T cell nonresponsive to the S region of both subtypes. Although responder/nonresponder status of the B10.M strain was dependent on the pre-S(2) subtype used for immunization, the anti-pre-S(2) antibody produced was totally cross-reactive on both subtypes. This is consistent with the conserved nature of the dominant pre-S(2) antibody-binding site and the highly polymorphic nature of the pre-S(2) sequence that represents the focus of T cell recognition. These data suggest that, to fully benefit from the inclusion of pre-S(2) region sequences, third generation hepatitis B virus vaccines should contain both the d and y subtype sequences of the pre-S(2) region to increase the frequency of pre-S(2) and S-specific antibody responses and to insure Th cell memory relevant to both viral subtypes. A second purpose of this study was to "design" a synthetic pre-S(2) immunogen based on combining the dominant B and T cell recognition sites into a single peptide. A composite peptide consisting of the dominant T cell recognition sequence p151-174 positioned N-terminal to the dominant B cell site p133-143 (i.e., p151-174(133-143] yielded an effective pre-S(2) synthetic immunogen. Interestingly, the orientation of the T and B cell determinants and the context of the T cell site within the larger composite peptide influenced both antibody fine specificity and T cell fine specificity.

Pathology of hepatic peroxisomes and mitochondria in patients with peroxisomal disorders

The morphology of hepatic peroxisomes in five patients with metabolic disorders believed to be due to inherited defects of peroxisomal function or biogenesis is described. Electron microscopy and cytochemical staining for catalase were used to identify peroxisomes in two boys with infantile Refsum's disease (IRD), a girl with autopsy confirmed neonatal adrenoleukodystrophy (NALD), and two boys with pseudo-Zellweger syndrome (PZS). In the patients with IRD and NALD hepatic peroxisomes were significantly reduced in size and number and contained electron dense centres. In the liver of the patients with PZS the peroxisomes were enlarged. Morphologically abnormal peroxisomes were also detected in autopsy tissue from one boy with PZS using electron microscopy. Lamellar-lipid inclusions and mitochondria with crystalline inclusions and/or abnormal cristae are also described in two patients, one with IRD, the other with NALD.

Importance of subtype in the immune response to the pre-S(2) region of the hepatitis B surface antigen. I. T cell fine specificity

Previous studies of murine T cell recognition of the pre-S(2) region of the hepatitis B surface Ag (HBsAg) identified high (H-2b,d,q), intermediate (H-2s,k), and low to nonresponder (H-2f) haplotypes. However, these studies utilized the y subtype of HBsAg. The purpose of this study was to examine the influence of viral subtype on T cell recognition of the pre-S(2) region and to identify specific T cell recognition sites in a panel of H-2 congenic strains. Immunization with pre-S(2) containing HBsAg particles of the d and y subtypes indicated that T cell recognition of the pre-S(2) region is predominantly subtype-specific in murine strains of eight different H-2 haplotypes. Furthermore, the B10.M strain (H-2f) classified as a T cell nonresponder to the y subtype of the pre-S(2) region responds efficiently to the d subtype, indicating that pre-S(2) responder status can be subtype-dependent as well as subtype-specific. Studies using a truncated pre-S(2) polypeptide and synthetic peptides illustrated that the C-terminal sequence (p148-174) of the pre-S(2) region is the dominant focus of T cell recognition in multiple murine strains. Specifically, 17 distinct T cell recognition sites were defined within the C-terminal half of the pre-S(2) region. The fine specificity of T cell recognition of the pre-S(2) region was dependent on the H-2 haplotype of the responding strain. T cell recognition of all 17 sites was subtype specific, which is consistent with the fact that the C-terminal sequence is highly polymorphic between the d and y subtypes of the pre-S(2) region. Lastly, it was shown that the ability of synthetic peptides to elicit T cells cross-reactive with the native pre-S(2) region was variable and depended on the nature of the immunizing peptide. The pre-S(2)-containing HBsAg vaccines currently in clinical trials are composed of ra single subtype, either d or y. The results of this study suggest that both subtypes should be incorporated to increase the frequency of T cell responders to the pre-S(2) region, and to insure Th cell memory relevant to infection with hepatitis B virus of either the d or y subtypes.

Management of low velocity gunshot-induced fractures

Bullets fired from civilian weapons are usually of low velocity, resulting in minimal tissue cavitation as compared to high-velocity weapons. A prospective protocol was initiated for patients sustaining a low-velocity gunshot to the extremity resulting in a stable, nonoperative fracture configuration. Treatment consisted of local irrigation and débridement, tetanus prophylaxis as required, a long acting cephalosporin intramuscularly, and splinting or casting of the fractured extremity. Twenty-five patients were managed by this protocol. This patient population was compared to a random retrospective sample of 25 patients with similar ballistic induced fractures and wounds managed by local débridement and 48 h of intravenous antibiotics. One infection occurred in each group, requiring further therapy. We conclude that the patient with a low-velocity gunshot induced fracture can be managed without the use of short-term intravenous antibiotics with no increased risk of infection.

Immunocytochemical localization of sphingolipid activator protein 2 (SAP-2) in normal and SAP-deficient fibroblasts

The intracellular localization of sphingolipid activator protein 2 (SAP-2) was determined immunocytochemically using an antiserum raised against a SAP-2 preparation from Gaucher spleen. The immunolabeling indicated that SAP-2 was largely localized in the lysosomes of fibroblasts from normal individuals. In some lysosomes the labeling was greatest around the perimeter of the matrix, suggesting an association between the activator and lysosomal membrane components. The labeling technique was also applied to fibroblasts from a patient with a unique sphingolipid storage disorder. Consistent with immunoblotting studies on electrophoretograms, both the patient and his affected fetal sibling were found to be deficient in immunoreactive SAP-2.

Functional identification of agretopic and epitopic residues within an HBcAg T cell determinant

Residues 120-131 within the hepatitis B core Ag (HBcAg) represent a dominant T cell recognition site for mice of the H-2S haplotype. This study was undertaken in order to identify residues within the p120-131 sequence which either interact with the TCR termed epitopic residues or interact with MHC class II molecules termed agretopic residues. For this purpose a panel of analogs of p120-131 composed of peptides containing single alanine substitutions for each residue was synthesized. These peptides were analyzed functionally for their ability to stimulate p120-131 or HBcAg-primed T cells and for their immunogenicity in B10.S or [B10.S X B10 (nonresponder)]F1 mice. Furthermore, analogs of p120-131 were used as stimulators and inhibitors of T cell activation in competitive inhibition experiments. Cumulatively these functional studies allowed us to identify residue 125 as a dominant epitopic residue and residues 127 and 129 as dominant agretopic residues. Furthermore, a p120-131 analog containing an alanine substitution for the dominant agretopic residue was immunogenic in B10.S mice, but was nonimmunogenic in (B10.S X B10)F1 mice indicating that T cell responsiveness is influenced by MHC class II gene dosage effects and can be inherited in an apparent recessive manner. In this study, critical residues involved in the immunogenicity of this dominant T cell determinant of HBcAg were defined, in a companion study, the influence of these residues on tolerogenicity was examined.