Gene therapy as a therapeutic intervention for vascular disease

Gene therapy for the treatment of many medical problems, including vascular disease, has become the subject of increasing discussion in both the scientific literature and the national press over the past decade. This review will examine the history and current status of gene therapy for vascular proliferative disorders and advanced chronic peripheral and cardiac ischemia.

The potential clinical utility of serum alpha-protryptase levels

BACKGROUND

Because biopsy criteria for diagnosing systemic mastocytosis are not precise, the value of serum alpha-protryptase levels in the work-up of suspected systemic mastocytosis should be considered.

OBJECTIVE

A retrospective analysis was performed on subjects with total tryptase serum levels that were high (>/=20 ng/mL), while beta-tryptase serum levels were normal (<1 ng/mL) or modestly elevated (1 to 5 ng/mL).

METHODS

Over a 3.5-year period, 52 qualifying specimens were identified from 1369 consecutive samples. The corresponding subjects were divided into those with suspected mastocytosis and those with suspected anaphylaxis. Subjects with suspected mastocytosis were subdivided into 3 subgroups on the basis of biopsy results (positive, negative, or not available). Subjects with suspected anaphylaxis were subdivided into living and deceased subgroups.

RESULTS

Among the 15 subjects who underwent biopsy, alpha-protryptase serum levels (the difference between directly-measured levels of serum total tryptase and beta-tryptase), when greater than 75 ng/mL (n = 9), were always associated with a positive biopsy result for systemic mastocytosis; levels from 20 to 75 ng/mL (n = 6) were associated with a positive biopsy result in 50% of subjects. alpha-Protryptase serum levels may be a more sensitive screening test than a bone marrow biopsy for this disorder. Also, elevated alpha-protryptase serum levels in some adult patients return to normal over time, suggesting that mast cell hyperplasia resolved in these patients. Finally, a high alpha-protryptase level may reveal anaphylaxis to be a presenting manifestation of systemic mastocytosis or mast cell hyperplasia.

CONCLUSION

Levels of serum alpha-protryptase, relative to those of beta-tryptase, appear to be useful in the diagnostic work-up and follow-up of subjects with suspected systemic mastocytosis.

The effect of 'non-critical' (<50%) stenosis on vein graft longitudinal resistance and impedance

OBJECTIVE

vein graft stenoses <50% cause minimal flow impairment, velocity elevation, or symptomatology and are therefore usually assumed to be "non-critical". The purpose of this study was to assess the effect of <50% vein graft stenosis on vein graft longitudinal impedance, as elevated impedance has been found to correlate with clinical graft failure.

METHODS

eight segments of non-reversed cryopreserved vein (mean length 23+/-1 cm; mean outer diameter 4.7+/-0.2 mm) were saline-perfused in vitro utilising a variable pulsatile perfusion pump, Windkessel, and clamp resistor simulating the haemodynamic conditions of arterial bypass. Proximal (Pprox) and distal (Pdist) pressure were continuously measured by fluid-filled catheter transduction, and flow (Q) by ultrasonic transit-time flowmetry. Waveforms were digitally recorded at 200 Hz at pulse rates ranging from 60-180 b.p.m. with mean flow (Q) of 154 ml/min and mean proximal pressure (Pprox) of 100 mmHg (max/min 120/90). Graded mid-graft stenoses of <50% were created using an inflatable vascular occluder and measured by the corresponding changes in mean pressure gradient (DeltaP=Pprox-Pdist) and Q (%stenosis=1-{DeltaPbaselineQstenosis/Delta PstenosisQbaseline}1/4). Vein graft longitudinal resistance (RL) was calculated as DeltaP/Q. After Fourier transformation, vein graft longitudinal impedance (ZL) was calculated as DeltaP/Q at each harmonic, with ZL determined by integration over 0-4 Hz. Results are reported as mean+/-S.E.M.

RESULTS

the desired levels of pressure and flow were established in all vein segments. Graded inflation of the occluder resulted in vein graft stenosis of 23+/-3% and 39+/-3%. This was accompanied by a mild reduction in Q (12% and 30%) and considerable increases in both RL (180% and 710%) and ZL (140% and 430%).

CONCLUSIONS

"non-critical" vein graft stenosis (<50%) causes minimal change in mean flow, but substantial elevations in longitudinal resistance and impedance. The contribution of "non-critical" stenosis to vein graft failure may be under-appreciated.

Adenoviral-mediated gene transfer of a constitutively active form of the retinoblastoma gene product attenuates neointimal thickening in experimental vein grafts

PURPOSE

Inappropriate or excessive vascular smooth muscle cell proliferation leads to the development of occlusive lesions in up to 50% of vein grafts. The purpose of this study was to test the hypothesis that induced overexpression of a cytostatic nonphosphorylatable form of the retinoblastoma protein (DeltaRb) would attenuate neointimal thickening in experimental vein grafts.

METHODS

A replication-deficient adenovirus vector that encoded a nonphosphorylatable, constitutively active form of DeltaRb was constructed (AdDeltaRb) and contained an NH2-terminal epitope tag from the influenza hemagglutinin molecule (HA). Forty-eight male New Zealand white rabbits underwent surgical exposure of the external jugular vein for transfection with either 3 x 10(10) plaque-forming units/mL AdDeltaRb (n = 16), 3 x 10(10) plaque-forming units/mL control adenovirus (AdBglII, n = 15), or vehicle (n = 17) for 10 minutes at 120 mm Hg. After vector exposure, the vein was excised and interposed end-to-end into the carotid circulation. After 5 days, 12 grafts (four from each group) were excised and assayed for genomic DeltaRb DNA with the polymerase chain reaction or for hemagglutinin molecule expression and localization with immunohistochemistry. The remainder of the grafts (n = 36) were perfusion-fixed after 4 weeks, and 5 microm sections prepared for digital planimetric analysis.

RESULTS

Polymerase chain reaction results identified the DeltaRb gene only in the grafts that were transfected with AdDeltaRb. Immunohistochemical analysis results revealed transgene expression in most of the endothelial cells and in many of the smooth muscle cells. After 4 weeks, the grafts that were exposed to AdDeltaRb exhibited a 22% reduction in neointimal thickness (vehicle, 77 +/- 7 microm; AdBglII, 75 +/- 5 microm; AdDeltaRb, 60 +/- 5 microm; P =.05), and medial thickness, luminal diameter, and other parameters were unchanged (medial thickness: vehicle, 72 +/- 10 microm; AdBglII, 85 +/- 7 microm; AdDeltaRb, 69 +/- 9 microm; P = NS; luminal diameter: vehicle, 4.5 +/- 0.2 mm; AdBglII, 4.4 +/- 0.2 mm; AdDeltaRb, 4.7 +/- 0.1 mm; P = NS).

CONCLUSION

With this delivery system, adenoviral-mediated gene transfer is highly efficient and induced overexpression of DeltaRb leads to a reduction in vein graft neointimal thickening.

Serum tryptase: an indicator of anaphylaxis following fluorescein angiography

BACKGROUND

Anaphylaxis is a potentially fatal complication of fluorescein angiography. It is diagnosed by clinical signs. Serum beta-tryptase serves as a specific indicator of mast cell activation and of anaphylactic shock that can be detected by radioimmunoassay.

METHOD

This is a report on a 48-year-old woman who developed anaphylaxis during fluorescein angiography. This study investigates the role of beta-tryptase in anaphylactic shock resulting from intravenous fluorescein angiogram.

RESULTS

A serum sample of beta-tryptase collected at the time of an adverse reaction to fluorescein angiography was determined by radioimmunassay to be elevated above 20 ng/ml (normal level <1 ng/ml). This indicates massive mast cell activation and anaphylactic shock.

CONCLUSION

This case is the first in which elevated levels of beta-tryptase in serum indicated that the systemic adverse reaction to fluorescein was mast cell dependent. Additionally, beta-tryptase levels can be assayed to detect anaphylactic reactions several hours after a precipitating event.

Identification and characterization of multiple forms of tryptase from human mast cells

Mast cell tryptase purified from human adult skin (AS), adult lung (AL) and newborn foreskin (NS) with a monoclonal antitryptase B2 immunoaffinity Sepharose column was further fractionated by HPLC using a Mono-S cation exchange column at pH 6.5. Tryptases exhibited two clearly separated major fractions, both of which also revealed at least two overlapping peaks. Native tryptase molecules from skin consisted of two diffuse protein bands in SDS-PAGE at about 31 and 35 kDa, whereas those from lung usually exhibited a predominant diffuse band at about 29 kDa. The forms of tryptases separated by Mono-S HPLC gave a different banding pattern in SDS-PAGE. Tryptase from NS exhibited chromatographic peaks that each showed Mr values approximately 1-3 kDa higher than those of tryptase from AS. By gel filtration, the Mr values for native major fractions of tryptases derived from AS and AL were 178 kDa and 141 kDa, respectively. After carbohydrate removal by glycanase, the observed differences in Mr values in SDS-PAGE reduced to two similar sharp bands of Mr approximately 28 kDa and 30 kDa for all tryptase preparations. AS and AL tryptases and their subfractions exhibited similar enzyme kinetic values and similar immunoreactivities in a tryptase immunoassay. Inactivation rates at physiologic ionic strength were similar for both AL and AS tryptases. The results show the enzymatic and antigenic similarity between lung and skin tryptases, and suggest that tryptase is stored mainly as beta-tryptase in human mast cells. Tryptase immunoassay measures similarly both lung and skin tryptases and, thus, this assay is suitable for detection of mast cell activation, in contrast to assays for other proteinases of mast cells, e.g. chymase, cathepsin G and carboxypeptidase, that are present in MC(TC) cells mainly in skin only.

Use of transvaginal ultrasonography to monitor the effects of tamoxifen on uterine leiomyoma size and ovarian cyst formation

To evaluate the effects of tamoxifen on leiomyomas and ovarian cysts in postmenopausal breast cancer patients, uterine and leiomyoma volumes were monitored sonographically in 17 postmenopausal women receiving postoperative tamoxifen for breast cancer; patients were examined twice with a mean of 1.18 +/- 0.17 years between examinations. The mean increase in leiomyoma volume was 1.26 +/- 0.73 cm3. The mean myoma volume was significantly larger at follow-up evaluation than at initial ultrasonography (5.75 +/- 1.09 cm3 versus 4.36 +/- 0.817 cm3, respectively; Wilcoxon signed rank test, P = 0.0218). Six women developed new leiomyomas. Of the 21 leiomyomas initially detected, 13 increased, six decreased, and two were unchanged in volume. The mean increase in uterine volume was 17.45 +/- 8.49 cm3. Three patients had simple ovarian cysts at initial ultrasonographic examination, two of which remained unchanged in size, and the third resolved. Two patients had newly developed simple ovarian cysts. The increase in uterine and leiomyoma volumes with the development of new leiomyomas and the persistence or development of ovarian cysts in some patients support the existence of agonistic tamoxifen effects. Serial measurements of uterine and leiomyoma volumes and surveillance for ovarian cysts is recommended for tamoxifen users.

The identification and characterization of umbilical cord blood-derived human basophils

Cross-linking allergen-specific immunoglobin E on human peripheral blood basophils results in the release of histamine and other inflammatory mediators that initiate allergy and asthma. The signaling pathways leading from IgE binding to mediator release have not been well established, mainly due to the difficulty in obtaining adequate numbers of highly purified basophils. It was the goal of this study to easily obtain Fc epsilonRI-positive human basophils in high yield and purity for studies of signal transduction pathways. We describe an in vitro culture system in which pulsing normal human cord blood leukocytes with interleukin-3 (IL-3) for 3-4 h followed by incubation in medium with fetal bovine serum generates a cell population that is predominately Fc epsilonRI positive between 14 and 28 days of culture. These cells resemble peripheral blood basophils when examined by light and electron microscopy. Like normal blood basophils, they express the integrins, CD11b, CD18, CD29, and CD49d. A majority of the IL-3-pulsed cells also express a marker recognized by the basophil-specific antibody, 2D7. Fc epsilonRI cross-linking results in a time and dose-dependent release of histamine. Fc epsilonRI cross-linking also stimulates protein-tyrosine phosphorylation, thought to be the first event leading to the IgE-mediated activation of peripheral blood basophils. These studies establish cord blood as an accessible source from which basophil-like cells can be developed to examine Fc epsilonRI-mediated signal transduction.

Gene therapy for vascular disease

Disorders of the vascular system are the leading cause of death and disability in the Western world. Mechanical interventions, such as angioplasty and bypass grafting, constitute the mainstay of treatment for end-stage occlusive lesions. Although initially successful in the majority of cases, the vascular response to injury and subsequent restenosis limits their long-term efficacy. Current work in the field of gene therapy has focused on the development of strategies to prevent these complications by the use of recombinant DNA technology. This review focuses on the latest advances in gene therapy for vascular disease, including the development of new vectors for vascular gene delivery, novel treatments for angioplasty-induced restenosis and vein graft intimal hyperplasia, and therapeutic angiogenesis.

Does pelvic magnetic resonance imaging differentiate among the histologic subtypes of uterine leiomyomata?

OBJECTIVE

To evaluate if pelvic magnetic resonance imaging (MRI) is reliable for differentiating leiomyoma subtypes.

DESIGN

Prospective study.

SETTING

Academic center.

PATIENT(S)

Forty-five patients underwent MRI before surgery for leiomyomata.

INTERVENTION(S)

One radiologist blinded to patient history and histologic diagnosis recorded the MRI characteristics and classification of the largest leiomyoma.

MAIN OUTCOME MEASURE(S)

Comparison of MRI and histologic diagnoses.

RESULT(S)

Leiomyoma subtypes were diagnosed accurately by MRI in 69% of cases. Magnetic resonance imaging had a 95% sensitivity and 72% specificity for diagnosing an uncomplicated leiomyoma and a 10% sensitivity and 100% specificity for a cellular leiomyoma. For cystic leiomyomata, the sensitivity was 80% and specificity was 98%, and for hemorrhagic leiomyomata, 100% and 86%, respectively. Magnetic resonance imaging correctly diagnosed all malignant tumors and did not incorrectly diagnose a leiomyoma as a leiomyosarcoma in any case. Ill-defined MRI margins were significantly more likely to be leiomyosarcoma, whereas well-defined margins were characteristic of benign lesions. Hemorrhagic leiomyomata were significantly more likely to be hyperintense on T1-weighted images than other subtypes.

CONCLUSION(S)

Although MRI is only fairly accurate in differentiating the subtypes of benign uterine smooth muscle tumors, signal intensities and margin characteristics are useful to distinguish accurately benign from malignant tumors.

Patterns of inflammatory responses following rechallenge of skin late-phase allergic reaction sites

BACKGROUND

Previous studies have suggested altered responses to repeat skin tests in the sites of IgE-mediated late-phase reactions (LPRs) induced within the previous 48 hours. To explore the possible modulation of LPRs in such rechallenge sites, we compared inflammatory responses in skin chambers induced over previous LPR and control sites.

METHODS

Skin blisters were induced and unroofed in 12 human subjects over two sites of previous LPRs induced by intradermal injection of pollen antigens 24 hours or 48 hours earlier and two sites previously injected with buffer diluent (B). Skin chambers containing the same antigens were appended to one intradermal antigen site (called Ag/Ag) and one intradermal B site (B/Ag), and B-containing chambers were placed over antigen (Ag/B) and B (B/B) intradermal sites. Fluids were collected after the first and the second through fifth hours of challenge.

RESULTS

In skin chamber challenges 24 hours after the intradermal injection, there was no significant difference after the first hours between the Ag/Ag or B/Ag sites in either histamine or tryptase levels; both were significantly higher than at Ag/B or B/B sites (p < 0.01). The same pattern of events was seen in fluids obtained from the second through fifth hours. The same pattern of findings was seen in examination of levels of the total leukocyte accumulation, total eosinophil accumulation, and frequency of activated (EG2+) eosinophils. Levels of lactoferrin, released from activated neutrophils, and eosinophil cationic protein, released from activated eosinophils, were also similar at Ag/Ag and B/Ag sites; both were significantly higher than at B/B sites, whereas levels at Ag/B sites were intermediate between those found at B/Ag and B/B sites. The pattern of events in skin chamber challenges 48 hours after intradermal injection was similar to that seen at 24 hours, except that levels of inflammatory mediators/cells in Ag/B sites were more intermediate between the B/Ag and B/B sites.

CONCLUSION

There is no significant alteration of mediator or inflammatory cell responses after antigen rechallenge of previous LPR sites when compared with those found in antigen challenge of non-LPR sites.

Assessing outcomes, costs, and benefits of emerging technology for minimally invasive saphenous vein in situ distal arterial bypasses

BACKGROUND

Instrumentation for a minimally invasive angioscopic in situ peripheral arterial bypass (MIAB) with catheter-directed side-branch occlusion has recently been approved for use. Despite the attractiveness of this approach (2 short incisions), benefits such as lower morbidity and shorter hospitalizations remain undocumented. To justify wide acceptance, minimally invasive surgical techniques must match conventional procedures in durability and cost while enhancing patient comfort. Often such comparisons are difficult during the implementation phase of a new procedure.

OBJECTIVE

To compare the outcomes of the MIAB procedures with a concurrent group of patients undergoing conventional in situ bypass procedures.

DESIGN

Retrospective review.

SETTING

University medical center.

PATIENT

The first 20 consecutive MIAB procedures in 19 patients performed between August 1, 1995, and July 31, 1997, were compared with 19 contemporaneous consecutive conventional in situ bypass procedures performed at the same institution.

MAIN OUTCOME MEASURES

Operative time, postoperative length of stay, hospital costs, complications, primary assisted and secondary patency, limb salvage, and survival.

RESULTS

The patient groups were comparable with respect to age, sex, incidence of smoking, coronary artery disease, hypertension, diabetes, renal failure, cerebrovascular disease, indication, and distal anastomosis level. The median operative time was significantly greater for the MIAB group (6.6 hours vs 5.7 hours; P=.009), and intraoperative completion arteriography more frequently showed retained arteriovenous fistulas in the MIAB group (55% vs 21%; P=.05). The median postoperative length of stay and total cost were 6.5 days and $18,000 for the MIAB group and 8 days and $27,800 for the conventional group (P > or = .05). There were no significant differences in major complications (10% in the MIAB group vs 11% in the conventional group), wound complications (10% vs 11%, respectively), primary assisted patency at 1 year (68%+/-11% vs 78%+/-10%, respectively), secondary patency at 1 year (79%+/-10% vs 88%+/-8%, respectively), limb salvage at 1 year (85%+/-10% vs 94%+/-6%, respectively), or patient survival at 1 year (89%+/-8% vs 61%+/-13%, respectively).

CONCLUSION

Patients undergoing the MIAB procedure avoided lengthy vein exposure incisions without sacrificing short-term results. There was a trend toward decreased hospital stay and cost, which may be further realized as the clinical experience broadens. Although longer follow-up and larger cohorts will always be required to define durability, immediate access to outcomes and costs on small numbers of patients facilitates the early assessment of emerging technology.

Regulation of Human Mast Cell β-Tryptase: Conversion of Inactive Monomer to Active Tetramer at Acid pH

At neutral pH, human mast cell β-tryptase is stabilized in its enzymatically active, tetrameric form by heparin, and resists inhibition by biologic protease inhibitors. After dissociation of β-tryptase from heparin, active tetramers rapidly convert to inactive monomers in an isotonic, neutral pH environment. Although reversible transition states probably exist during this conversion, once inactive monomers form, addition of heparin fails to reconstitute active tetramer at neutral pH. The current study shows that complete reactivation of inactive monomers can occur at acidic pH in a heparin-independent manner. The respective rate-determining steps for formation of tetramer and active enzyme from inactive monomers exhibit second and first order kinetics based on an analysis of initial reaction rates. The optimal pH for tetramer formation and reactivation is about 6, suggesting His residues play a critical role. The optimal ionic strength equivalent is 160 mM NaCl; and the optimal temperature range is 22°C to 37°C. We propose a sequential three-step reactivation process at acidic pH, dimerization of monomers (rate-determining second order step), rapid formation of inactive tetramers, and slow formation of active tetramers (overall rate-determining first order step). Whether reactivation of human β-tryptase occurs at extracellular or intracellular sites, where the pH is acidic in vivo, should be considered.

Regulation of human mast cell beta-tryptase: conversion of inactive monomer to active tetramer at acid pH

At neutral pH, human mast cell beta-tryptase is stabilized in its enzymatically active, tetrameric form by heparin, and resists inhibition by biologic protease inhibitors. After dissociation of beta-tryptase from heparin, active tetramers rapidly convert to inactive monomers in an isotonic, neutral pH environment. Although reversible transition states probably exist during this conversion, once inactive monomers form, addition of heparin fails to reconstitute active tetramer at neutral pH. The current study shows that complete reactivation of inactive monomers can occur at acidic pH in a heparin-independent manner. The respective rate-determining steps for formation of tetramer and active enzyme from inactive monomers exhibit second and first order kinetics based on an analysis of initial reaction rates. The optimal pH for tetramer formation and reactivation is about 6, suggesting His residues play a critical role. The optimal ionic strength equivalent is 160 mM NaCl; and the optimal temperature range is 22 degrees C to 37 degrees C. We propose a sequential three-step reactivation process at acidic pH, dimerization of monomers (rate-determining second order step), rapid formation of inactive tetramers, and slow formation of active tetramers (overall rate-determining first order step). Whether reactivation of human beta-tryptase occurs at extracellular or intracellular sites, where the pH is acidic in vivo, should be considered.

Immunohistochemical detection of human basophils in late-phase skin reactions

BACKGROUND

Human basophils are difficult to detect with classic histochemical stains at sites of allergic inflammation. The 2D7 anti-basophil monoclonal antibody was used to identify basophils in skin during the late-phase response to a cutaneous allergen challenge.

METHODS

The 2D7 monoclonal antibody was used on protease-digested sections of skin biopsy specimens obtained 6 and 24 hours after an allergen or buffer challenge. The skin chamber technique was used to compare buffer- and allergen-challenged sites at 6 hours, and intradermal injection of allergen was used to compare allergen-challenged sites at 6 and 24 hours.

RESULTS

Dramatic increases in the numbers of 2D7+ cells and in tissue staining by 2D7 were observed 6 hours after allergen challenge compared with buffer challenge. Histamine levels in skin chamber fluid varied with 2D7+ cell concentrations. By 24 hours, 2D7+ cells and tissue staining appeared to diminish but were still detectable in the allergen-challenged sites. Basophils localized primarily in and around blood vessels, whereas mast cells remained mostly in the superficial dermis. Mast cells were 2D7- in both the allergen- and buffer-challenged skin. Metachromatic staining of 2D7+ basophils with toluidine blue was absent in these tissue sections.

CONCLUSIONS

The 2D7 monoclonal antibody provides a more sensitive and precise marker than histochemical staining for human basophil involvement during the late-phase response to an allergen challenge. Basophil infiltration was observed at 6 hours only after allergen challenge and persisted at similar levels by 24 hours.

Chromosomal analysis of early fetal losses in relation to transvaginal ultrasonographic detection of fetal heart motion after infertility

OBJECTIVE

To evaluate the prognostic value of transvaginal ultrasound (TVUS) detection of fetal heart motion (FHM) in view of maternal age and chromosomal analysis of spontaneously aborted fetal tissue.

DESIGN

A 3-year retrospective, descriptive study.

SETTING

Two medical center-based infertility-care facilities.

PATIENT(S)

336 pregnancies were initiated by intrauterine insemination or embryo transfer for women of reproductive age who were seeking infertility treatment.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

beta hCG levels measured > 40 mIU/mL at 4-5 weeks' gestation and were followed by an initial TVUS at 5-8 weeks. Of these pregnancies, 52 ended in a first trimester loss. Twenty were defined by failure to detect FHM by 7 weeks' gestation (Group I), and 32 were marked by the loss of prior FHM at a mean of 2.6 weeks later (Group II). Fetal tissue was removed by dilatation and suction curettage. Cytogenetic studies were performed from short-term cultures of dissected chorionic villi and/or sac.

RESULT(S)

Chromosomal aberrations were found in 75.0% of abortuses in Group I and 65.6% in Group II. Different types of chromosomal abnormalities were present in each these groups. The maternal age-related trisomies which can progress to term (i.e., 13, 18, 21) were associated with early TVUS detection of FHM. The frequency of chromosomal abnormalities varied significantly with maternal age, with normal fetal karyotypes in 7 of 11 (63.6%) women < 35 years, but only in 9 of 41 (22.0%) women > or = 35 years despite the detection of FHM in 24 of 41 (58.5%) of these older women. Detection of FHM was associated with pregnancies continuing beyond the first trimester in 284 of 316 (90.0%) overall, but differed significantly with age (166 of 174 [95.4%] women < 35 years vs. 118 of 142 [83.1%] women > or = 35 years).

CONCLUSION(S)

Although the occurrence of chromosomal abnormalities in spontaneous demises did not differ according to TVUS detection of FHM, the types of aberrations were distributed differently. Since maternal age remains a significant factor in early fetal loss, TVUS detection of FHM should not be as reassuring for women > or = 35 years as for younger women.

The use of transvaginal ultrasound and saline infusion sonohysterography for the evaluation of asymptomatic postmenopausal breast cancer patients on tamoxifen

Tamoxifen has been shown to decrease the recurrence rate of breast cancer. Evidence that tamoxifen use may be associated with an increased risk of endometrial cancer has caused investigators to recommend routine invasive sampling. We have assessed a minimally invasive alternative for endometrial surveillance of tamoxifen-treated patients utilizing transvaginal ultrasound and saline infusion sonohysterography. Asymptomatic women (n = 44) with breast cancer on postoperative tamoxifen treatment were referred to our gynecological ultrasound unit. Initially, the endometrial echo was measured with unenhanced transvaginal ultrasound. If a distinct echo measured < or = 5 mm, no further procedure was performed. For thickened or inadequately visualized echoes, sonohysterography was performed. If a thin echo was noted on sonohysterography, no further procedure was performed. If focal changes were detected, hysteroscopy/dilatation and curettage (D&C) was performed. For generalized symmetrically thickened echoes, a blind biopsy was done. If sonohysterography was unsuccessful, hysteroscopy/D&C was performed. Eleven (25%) patients had thin unenhanced echoes of < or = 5 mm. Twenty-five (57%) patients had thickened endometrial echoes. Three (7%) had naturally occurring endometrial fluid outlining a polyp. An endometrial echo could not be visualized in five (11%) patients. Sonohysterography was successfully performed in 21 out of 30 (70%) patients with either thickened or non-visualized unenhanced echoes. Of these, two patients had thin endometria with coexisting myomas; seven had thin endometria with typical tamoxifen-induced subendometrial changes: and seven had focal polypoid thickening confirmed by hysteroscopy/D&C. Histology revealed carcinoma associated with two, proliferation in one and four polyps. Five patients had thickened unenhanced echoes with symmetrically thickened single-layer measurements on sonohysterography. Histology revealed that three were proliferative, one was inactive and one was hyperplastic. In the nine patients with unsuccessful sonohysterography, hysteroscopy/D&C revealed inactive endometria in six, and three polyps. Our paradigm of evaluating the endometrial response to tamoxifen is concluded to overcome the shortcomings of either unenhanced transvaginal ultrasound or blind biopsy alone while it kept the number of invasive sampling procedures to 55% (24 out of 44).

Nasal airway changes assessed by acoustic rhinometry and mediator release during immediate and late reactions to allergen challenge

BACKGROUND

We have found that acoustic rhinometry is a reliable means of assessing nasal airway caliber changes during the immediate reaction to nasal allergen challenge of sensitive subjects. Comparison of such changes with symptoms and patterns of mediator release could help in the understanding of mechanisms of immediate and late-phase reactions after allergen challenge and their clinical relevance.

METHODS

Nasal minimal cross-sectional area (MCA) was assessed sequentially for 6 hours after two blinded challenges in random order with pollen antigens and buffer diluent in five sensitive human subjects. Comparisons were made with: (1) symptom scores; (2) olfaction changes; and (3) nasal secretion levels of histamine, tryptase, leukotriene C4, serum albumin (a marker of vascular permeability), lactoferrin (a marker of local glandular secretion), and inflammatory cells in nasal scrapings.

RESULTS

In four of five subjects there was a significantly greater decrease in MCA after antigen challenge than after diluent challenge, correlating with the degree of subjective nasal congestion. In two of these four subjects there was a prominent second late-phase decrease in MCA at 3 to 5 hours, whereas the MCA was persistently decreased in an additional subject with accompanying subjective congestion. No significant decrease in olfactory acuity occurred. Levels were significantly higher in nasal secretions obtained after antigen challenge than in those obtained after buffer challenge with histamine (9 +/- 2.7 ng/ml vs 1.2 +/- 0.5 ng/ml; p = 0.04); tryptase (95 +/- 83 ng/ml vs 3 +/- 0.9 ng/ml; p = 0.02), leukotriene C4 (5293 +/- 1385 ng/ml vs 578 +/- 183 ng/ml; p = 0.02), and albumin (123 +/- 9 ng/ml vs 19 +/- 1.6 ng/ml; p = 0.005) but not with lactoferrin (4.6 +/- 1.2 ng/ml vs 4.1 +/- 28 ng/ml; p = not significant). Granulocyte exudation was seen after antigen challenge but not after buffer diluent challenge. However, there was not a precise correlation between decreases in MCA with changes in levels of these mediators in individual subjects.

CONCLUSIONS

Acoustic rhinometry can quantitatively assess congestion during immediate and late-phase reactions after nasal challenge without significant correlation to the degree of individual inflammatory events assessed.

Human tryptase fibrinogenolysis is optimal at acidic pH and generates anticoagulant fragments in the presence of the anti-tryptase monoclonal antibody B12

Human tryptase is uniquely regulated by its association with heparin and resists inhibition by biological protease inhibitors. The effects of pH and B12, an IgG anti-tryptase mAb, on cleavage of the synthetic substrate tosyl-Gly-Pro-Lys-p-nitroanilide and of the biological substrate fibrinogen by tryptase were examined. Tosyl-Gly-Pro-Lys-pnitroanilide cleavage was optimal at neutral pH and was inhibited by the B12 mAb at acidic and neutral pH values. At pH 7.5, inhibition was reversible and noncompetitive. In contrast, the optimal pH for tryptase to cleave fibrinogen was acidic. B12 dramatically enhanced the rate and extent that tryptase cleaved all three fibrinogen subunits at pH 6.0 to 6.5, but inhibited these activities at neutral pH. Major fibrinogen cleavage fragments generated at acidic pH by the B12:tryptase complex were identical with those made by plasmin. Thus, at acid pH, tryptase alone destroyed the ability of fibrinogen to clot, while the B12:tryptase complex increased the rate of fibrinogenolysis and also generated the anticoagulant, fragment D. The acidic pH optimum for tryptase fibrinogenolysis may direct this activity to tissue sites of inflammation. A putative biological equivalent to B12 would limit tryptase fibrinogenolytic activity at sites of neutral pH, such as blood, but would augment activity at acidic sites.

Immunocytochemical localization of chymase to cytoplasmic vesicles after rat peritoneal mast cell stimulation by compound 48/80

The subcellular events responsible for release of mediators by mast cells may help to clarify roles for mast cells in health and disease. In this study we show that the granule-associated protease chymase is also within cytoplasmic vesicles in appropriately stimulated rat peritoneal mast cells. Rat peritoneal mast cells were recovered before or 1-10 sec after exposure to the secretogogue compound 48/80 (10 micrograms/ml) and then were examined by radioimmunoassay to quantify histamine release or were processed, using routine methods for postembedding immunoelectron microscopy, to identify the subcellular localization of chymase. In comparison to unstimulated cells, compound 48/80 stimulated cells in two independent experiments showed an increase (15%, 28%) in the surface area of the cell and a decrease (12%, 6%) in the surface area of the total granule compartment before degranulation channel formation. These global cellular changes occurred in a background of transient but significant (p < 0.01) increases in the area and number of chymase-immunoreactive vesicles per microns2 cytoplasm. These changes were detectable at 5 or 7 sec after stimulation with compound 48/80 but returned to near prestimulation levels by 9 or 10 sec after addition of compound 48/80 (total cumulative histamine release was 28% by 8 sec and 47% by 14 sec). These observations suggest that vesicles participate in the early stages of regulated secretion of chymase from rat peritoneal mast cells.

Mast cell activation in arthritis: detection of alpha- and beta-tryptase, histamine and eosinophil cationic protein in synovial fluid

1. Although mast cell hyperplasia is a feature of rheumatoid arthritis and osteoarthritis, the extent and nature of mast cell activation in joint disease have not been clearly established. 2. We have investigated the levels of mast cell tryptase and histamine and also of eosinophil cationic protein in synovial fluid collected from 31 patients with rheumatoid arthritis, 14 with seronegative spondyloarthritis and nine with osteoarthritis. Two RIAs for tryptase were employed: one with monoclonal antibody AA5, which was found to bind equally well to both alpha and beta isoforms on Western blots of the recombinant enzyme, and the other with antibody G5, which recognizes predominantly beta-tryptase. 3. alpha-Tryptase, which is likely to be released constitutively from mast cells, appeared to be the major form in synovial fluid, as the assay with antibody AA5 detected appreciably more tryptase than that with antibody G5. beta-Tryptase, which is released on anaphylactic activation of mast cells, was detected in 14 out of 45 synovial fluid samples studied, with concentrations of up to 12 micrograms/l measured by the G5 assay. The apparent levels of beta-tryptase, but not of alpha-tryptase, were closely correlated with those of histamine in the synovial fluid. Patients with osteoarthritis appeared to have a greater proportion of beta-tryptase in the synovial fluid than those with rheumatoid arthritis, as well as higher concentrations of histamine. Eosinophil cationic protein was present at high levels in the synovial fluid, although eosinophil numbers were low, and its concentrations were not correlated with the concentrations of the mast cell products. 4. These data suggest that anaphylactic degranulation of mast cells may have occurred to a greater extent in osteoarthritis than in rheumatoid arthritis, despite the relative lack of synovial inflammation in osteoarthritis. Although the eosinophil cationic protein detected may not reflect eosinophilic inflammation in the joint, the presence in synovial fluid of tryptase of both major forms, and of histamine, appears to indicate that mast cell products are secreted constitutively, as well as by processes of anaphylactic degranulation in rheumatoid arthritis, seronegative spondyloarthritis and osteoarthritis.

Human tryptase fibrinogenolysis is optimal at acidic pH and generates anticoagulant fragments in the presence of the anti-tryptase monoclonal antibody B12

Human tryptase is uniquely regulated by its association with heparin and resists inhibition by biological protease inhibitors. The effects of pH and B12, an IgG anti-tryptase mAb, on cleavage of the synthetic substrate tosyl-Gly-Pro-Lys-p-nitroanilide and of the biological substrate fibrinogen by tryptase were examined. Tosyl-Gly-Pro-Lys-pnitroanilide cleavage was optimal at neutral pH and was inhibited by the B12 mAb at acidic and neutral pH values. At pH 7.5, inhibition was reversible and noncompetitive. In contrast, the optimal pH for tryptase to cleave fibrinogen was acidic. B12 dramatically enhanced the rate and extent that tryptase cleaved all three fibrinogen subunits at pH 6.0 to 6.5, but inhibited these activities at neutral pH. Major fibrinogen cleavage fragments generated at acidic pH by the B12:tryptase complex were identical with those made by plasmin. Thus, at acid pH, tryptase alone destroyed the ability of fibrinogen to clot, while the B12:tryptase complex increased the rate of fibrinogenolysis and also generated the anticoagulant, fragment D. The acidic pH optimum for tryptase fibrinogenolysis may direct this activity to tissue sites of inflammation. A putative biological equivalent to B12 would limit tryptase fibrinogenolytic activity at sites of neutral pH, such as blood, but would augment activity at acidic sites.