Mechanism of Ca2+ and monosaccharide binding to a C-type carbohydrate-recognition domain of the macrophage mannose receptor

Site-directed mutagenesis has been used to identify residues that ligate Ca2+ and sugar to the fourth C-type carbohydrate-recognition domain (CRD) of the macrophage mannose receptor. CRD-4 is the only one of the eight CRDs of the mannose receptor to exhibit detectable monosaccharide binding when expressed in isolation, and it is central to ligand binding by the receptor. CRD-4 requires two Ca2+ for sugar binding, like the CRD of rat serum mannose-binding protein (MBP-A). Sequence comparisons between the two CRDs suggest that the binding site for one Ca2+, which ligates directly to the bound sugar in MBP-A, is conserved in CRD-4 but that the auxiliary Ca2+ binding site is not. Mutation of the four residues at positions in CRD-4 equivalent to the auxiliary Ca2+ binding site in MBP-A indicates that only one, Asn728, is involved in ligation of Ca2+. Alanine-scanning mutagenesis was used to identify two other asparagine residues and one glutamic acid residue that are probably involved in ligation of the auxiliary Ca2+ to CRD-4. Sequence comparisons with other C-type CRDs suggest that the proposed binding site for the auxiliary Ca2+ in CRD-4 of the mannose receptor is unique. Evidence that the conserved Ca2+ in CRD-4 bridges between the protein and bound sugar in a manner analogous to MBP-A was obtained by mutation of one of the amino acid side chains at this site. Ring current shifts seen in the 1H NMR spectra of methyl glycosides of mannose, GlcNAc, and fucose in the presence of CRD-4 and site-directed mutagenesis indicate that a stacking interaction with Tyr729 is also involved in binding of sugars to CRD-4. This interaction contributes about 25% of the total free energy of binding to mannose. C-5 and C-6 of mannose interact with Tyr729, whereas C-2 of GlcNAc is closest to this residue, indicating that these two sugars bind to CRD-4 in opposite orientations. Sequence comparisons with other mannose/GlcNAc-specific C-type CRDs suggest that use of a stacking interaction in the binding of these sugars is probably unique to CRD-4 of the mannose receptor.

Mammographically detected, clinically occult ductal carcinoma in situ treated with breast-conserving surgery and definitive breast irradiation

PURPOSE

Ductal carcinoma in situ (DCIS) is increasingly detected as a nonpalpable lesion on mammographic screening performed for the early detection of breast cancer. Because of the growing incidence of mammographically detected DCIS, the present study was undertaken to determine the outcome of treatment of nonpalpable, mammographically detected intraductal carcinoma of the breast using breast-conserving surgery and definitive breast irradiation.

MATERIALS AND METHODS

An analysis was performed of 110 women who presented with unilateral, nonpalpable, mammographically detected intraductal carcinoma of the breast and who were treated with breast-conserving surgery and definitive breast irradiation at 10 institutions in Europe and the United States. In all patients, complete gross excision of the primary tumor was performed, and breast irradiation was delivered with definitive intent. When performed, pathologic axillary lymph node staging was node negative (n=29). The median follow-up time was 9.3 years.

RESULTS

The 10-year actuarial overall survival rate was 93%, and the 10-year actuarial cause-specific survival rate was 96%. The 10-year actuarial rate of freedom from distant metastases was 96%. There were 15 local recurrences in the treated breast. The actuarial rate of local failure was 7% at 5 years and 14% at 10 years. The histology of the local recurrence was intraductal carcinoma in 9 cases and invasive ductal carcinoma (with or without associated intraductal carcinoma) in 6 cases. The median time to local recurrence was 5.0 years (mean, 5.4; range, 2.1-15.2). With a median follow-up time of 4.4 years after salvage treatment, 14 of the 15 patients with local recurrence were alive without evidence of disease at the time of last follow-up examination. The crude incidence of local recurrence was 7% (3/42) when the final pathology margin of tumor excision was negative, 29% (5/17) when the margin was close or positive, and 14% (7/51) when the margin was unknown. There was no difference in the rate of local recurrence based on pathologic characteristics of the primary tumor.

DISCUSSION

Results from the present study demonstrate high rates of overall survival, cause-specific survival, and freedom from distant metastases at 10 years following the treatment of nonpalpable, mammographically detected DCIS of the breast using breast-conserving surgery and definitive breast irradiation. Local recurrences within the treated breast were detected early and were treated with salvage for cure. These results support the initial treatment of nonpalpable, mammographically detected DCIS of the breast using breast-conserving surgery and definitive breast irradiation. Improvements in patient selection have the potential to reduce the risk of local recurrence.

Brachytherapy or electron beam boost in conservation therapy of carcinoma of the breast: a nonrandomized comparison

PURPOSE

The results of breast-conservation therapy using breast irradiation and a boost to the tumor excision site with either electron beam or interstitial 192Ir implant are reviewed.

METHODS AND MATERIALS

A total of 701 patients with histologically confirmed Stage T1 and T2 carcinoma of the breast were treated with wide local tumor excision or quadrantectomy and breast irradiation. The breast was treated with tangential fields using 4 or 6 MV photons to deliver 48 to 50 Gy in 1.8 to 2 Gy daily dose, in five weekly fractions. In 80 patients the regional lymphatics were irradiated. In 342 patients with Stage T1 and 107 with Stage T2 tumors, boost to the primary tumor excision site was delivered with 9 MeV and, more frequently, with 12 MeV electrons. In 91 patients with Stage T1 and 38 patients with Stage T2 tumors an interstitial 192Ir implant was performed. Tumor control, disease-free survival, cosmesis, and morbidity of therapy are reviewed. Minimum follow-up is 4 years (median 5.6 years; maximum, 24 years).

RESULTS

The overall local tumor recurrence rates were 5% in the T1 and 11% in the T2 tumor groups. There was no significant difference in the breast relapse rate in patients treated with either electron beam or interstitial 192Ir boost. Regional lymph node recurrences were 1% in patients with T1 and 5% with T2 tumors. Distant metastases were recorded in 5% of the T1 and 23% of the T2 groups. The 10-year actuarial disease-free survival rates were 87% for patients with T1 and 75% with T2 tumors. Disease-free survival was exactly the same in patients receiving either electron beam or interstitial 192Ir boost. Cosmesis was rated as excellent/good in 84% of patients with T1 tumors treated with electron beam and 81% of patients treated with interstitial implant, and 74 and 79% respectively, in patients with T2 tumors.

CONCLUSIONS

Breast-conservation therapy is an effective treatment for patients with T1 and T2 carcinoma of the breast. There is no difference in local tumor control, disease-free survival, cosmesis, or morbidity in patients treated with either electron beam or interstitial 192Ir implant boost. Clinical trials in progress will further elucidate this controversial subject.

Stress and strain distribution within the intact femur: compression or bending?

The aim of this research was to test the hypothesis that the intact femur is loaded predominately in compression. The study was composed of two parts: a finite element analysis of the intact femur to assess if a compressive stress distribution could be achieved in the diaphyseal region of the femur using physiological muscle and joint contact forces; a simple radiological study to assess the in vivo deflections of the femur during one legged stance. The results of this investigation strongly support the hypothesis that the femur is loaded primarily in compression, and not bending as previously thought. The finite element analysis demonstrated that a compressive stress distribution in the diaphyseal femur can be achieved, producing a stress distribution which appears to be consistent with the femoral cross-sectional geometry. The finite element analysis also predicted that for a compressive load case there would be negligible deflections of the femoral head. The radiological study confirmed this, with no measurable in vivo deflection of the femur occurring during one legged stance.

Genetic variants of human T-lymphotrophic virus type II in American Indian groups

The human T-lymphotropic virus type II (HTLV-II) is found in many New World Indian groups in North and South America and may have entered the New World from Asia with the earliest migration of ancestral Amerindians over 15,000 years ago. To characterize the phylogenetic relationships of HTLV-II strains infecting geographically diverse Indian populations, we used polymerase chain reaction to amplify HTLV-II sequences from lymphocytes of seropositive Amerindians from Brazil (Kraho, Kayapo, and Kaxuyana), Panama (Guaymi), and the United States (the Navajo and Pueblo tribes of the southwestern states and the Seminoles of Florida). Sequence analysis of a 780-base pair fragment (located between the env gene and the second exons of tax/rex) revealed that Amerindian viruses clustered in the same two genetic subtypes (IIa and IIb) previously identified for viruses from intravenous drug users. Most infected North and Central American Indians had subtype IIb, while HTLV-II infected members of three remote Amazonian tribes clustered as a distinct group within subtype IIa. These findings suggest that the ancestral Amerindians migrating to the New World brought at least two genetic subtypes, IIa and IIb. Because HTLV-II strains from Amazonian Indians form a distinct group within subtype HTLV-IIa, these Brazilian tribes are unlikely to be the source of IIa viruses in North American drug users. Finally, the near identity of viral sequences from geographically diverse populations indicate that HTLV-II is a very ancient virus of man.

Accelerated induction therapy and resection for poor prognosis stage III non-small cell lung cancer

BACKGROUND

Induction therapy and resection may improve the survival of patients with poor prognosis stage III non-small cell lung cancer, at the cost of significant treatment prolongation. The purpose of this study was to assess toxicity, response, and survival of an accelerated induction regimen and resection in poor prognosis stage III non-small cell lung cancer.

METHODS

Forty-two surgically staged patients with poor prognosis stage III non-small cell lung cancer received 11 days of induction treatment consisting of 96 hours of continuous chemotherapy infusions of cisplatin (20 mg.m-2.day-2), 5 fluorouracil (1,000 mg.m-2.day-2), and etoposide (75 mg.m-2.day-2) concurrent with accelerated fractionation radiation therapy (1.5 Gy twice a day, to a dose of 27 Gy). Induction was followed in 4 weeks by resection. Postoperatively, a second course of continuous chemotherapy and concurrent accelerated fractionation radiation therapy (postoperative dose 13 to 36 Gy) was given.

RESULTS

Despite some degree of induction toxicity in all patients there was only one induction death (2.4%). A clinical partial response was seen in 24 patients (57%). Thirty-six patients (86%) underwent thoracotomy, and resection was possible in 33 (79%). Pathologic downstaging was seen in 17 patients (40%), and 2 patients (5%) had no residual carcinoma at operation. There were 11 postoperative complications (31%) and 4 postoperative deaths (11%). Thirteen patients (31%) are alive and disease-free, 24 (57%) have persistent disease or have recurred (15 distant, 5 locoregional, 4 both), and 9 patients are alive with disease. The median survival is 21 months and the 2-year Kaplan-Meier survival is 43%, with no differences identified between stages IIIA and IIIB patients (p = 0.63).

CONCLUSIONS

We conclude that accelerated induction therapy and resection in poor prognosis stage III non-small cell lung cancer (1) is toxic, with a 12% treatment mortality; (2) is effective with a 79% resection rate and 40% pathologic downstaging rate; (3) provides excellent local control; (4) may prolong survival; and (5) is of value in stage IIIB as well as stage IIIA patients.

Use of a lucite beam spoiler for high-energy breast irradiation

Treatment planning for breast cancer is a challenge for bridge separations greater than 24 cm. protocols require dose homogeneity to the breast parenchyma to 10% while maintaining good cosmesis (skin sparing). Low-energy beams (6 MV or lower) may not achieve protocol specifications because of lateral or medial hot spots. The buildup region for high-energy beams (i.e., 18 MV) may lead to underdosing in the superficial regions. Adding bolus will pull the isodoses to surface, surrendering skin sparing. A spoiler will increase the contribution of scattered medium energy electrons and photons, thereby increasing superficial dosing and maintaining skin sparing due to displacement of the spoiler from the skin. We chose Lucite as the spoiler material for our 18-MV beam. Buildup measurements were performed with a parallel-plate ionization chamber to find the optimal spoiler thickness of 18 mm at a spoiler-to-skin distance of 22 cm. A breast phantom was designed allowing thermoluminescent dosimeter measurements. The spoiler has increased the percent depth dose from the depths of 0.5 cm to 3.0 cm to mimic those delivered by a 6 MV beam, while the relative skin dose was held to 50%. Our treatment schema is typically 6-MV photons with customized compensation for half or more of the fractions and uncompensated 18-MV photons with the spoiler for the remaining fractions. The spoiler may be used in conjunction with thin bolus (1.0 cm) for therapeutic dosing to the skin (scars, inflammatory disease, etc.). The treatment plans have maintained dose homogeneity for large patients, without consequence of skin reaction.

Factors influencing cosmetic results after conservation therapy for breast cancer

PURPOSE

Host, tumor, and treatment-related factors influencing cosmetic outcome are analyzed for patients receiving breast conservation treatment.

METHODS AND MATERIALS

Four-hundred and fifty-eight patients with evaluable records for cosmesis evaluation, a subset of 701 patients treated for invasive breast cancer with conservation technique between 1969 and 1990, were prospectively analyzed. In 243 patients, cosmetic evaluation was not adequately recorded. Cosmesis evaluation was carried out from 3.7 months to 22.3 years, median of 4.4 years. By pathologic stage, tumors were 62% T1N0, 14% T1N1, 15%, T2N0, and 9% T2N1. The majority of patients were treated with 4-6 MV photons. Cosmetic evaluation was rated by both patient and physician every 4-6 months. A logistic regression analysis was completed using a stepwise logistic regression. P-values of 0.05 or less were considered significant. Excellent cosmetic scores were used in all statistical analyses unless otherwise specified.

RESULTS

At most recent follow-up, 87% of patients and 81% of physicians scored their cosmetic outcome as excellent or good. Eighty-two percent of physician and patient evaluations agreed with excellent-good vs. fair-poor rating categories. Analysis demonstrated a lower proportion of excellent cosmetic scores when related to patient age > 60 years (p = 0.001), postmenopausal status (p = 0.02), black race (p = 0.0034), and T2 tumor size (p = 0.05). Surgical factors of importance were: volume of resection > 100 cm3 (p = 0.0001), scar orientation compliance with the National Surgical Adjuvant Breast Project (NSABP) guidelines (p = 0.0034), and > 20 cm2 skin resected (p = 0.0452). Extent of axillary surgery did not significantly affect breast cosmesis. Radiation factors affecting cosmesis included treatment volume (tangential breast fields only vs. three or more fields) (p = 0.034), whole breast dose in excess of 50 Gy (p = 0.0243), and total dose to tumor site > 65 Gy (p = 0.06), as well as optimum dose distribution with compensating filters (p = 0.002). Daily fraction size of 1.8 Gy vs. 2.0 Gy, boost vs. no boost, type of boost (brachytherapy vs. electrons), total radiation dose, and use of bolus were not significant factors. Use of concomitant chemotherapy with irradiation impaired excellent cosmetic outcome (p = 0.02). Use of sequential chemotherapy or adjuvant tamoxifen did not appear to diminish excellent cosmetic outcomes (p = 0.31). Logistic regression for excellent cosmetic outcome analysis was completed for age, tumor size, menopausal status, race, type of surgery, volume of breast tissue resected, scar orientations, whole breast radiation dose, total radiation dose, number of radiation fields treated, and use of adjuvant chemotherapy. Significant independent factors for excellent cosmetic outcome were: volume of tissue resected (p = 0.0001), type of surgery (p = 0.0001), breast radiation dose (p = 0.005), race (p = 0.002), and age (p = 0.007).

CONCLUSIONS

Satisfactory cosmesis was recorded in 81% of patients. Impaired cosmetic results are more likely with improper orientation of tylectomy and axillary incisions, larger volume of breast resection, radiation dose to the entire breast in excess of 50.0 Gy, and concurrent administration of chemotherapy. Careful selection of treatment procedures for specific patients/tumors and refinement in surgical/irradiation techniques will enhance the cosmetic results in breast conservation therapy.

Viral dynamics in human immunodeficiency virus type 1 infection

The dynamics of HIV-1 replication in vivo are largely unknown yet they are critical to our understanding of disease pathogenesis. Experimental drugs that are potent inhibitors of viral replication can be used to show that the composite lifespan of plasma virus and virus-producing cells is remarkably short (half-life approximately 2 days). Almost complete replacement of wild-type virus in plasma by drug-resistant variants occurs after fourteen days, indicating that HIV-1 viraemia is sustained primarily by a dynamic process involving continuous rounds of de novo virus infection and replication and rapid cell turnover.

Management of the axilla in patients with breast cancers one centimeter or smaller

Very small breast cancers are being diagnosed with increased frequency, and, until recently, little information regarding the incidence of axillary lymph node metastases in these most favorable tumors was available. Moreover, scarce data exist regarding axillary failure in this cohort as a function of initial treatment, be it surgery, radiation, or simply observation. In the present study, limited to women with invasive cancers measuring no more than 10 mm, the incidence of pathologically positive axillary nodes was 12.3%. The incidence of nodal metastases was influenced by tumor size (albeit not quite significantly, p = .08); not one patient with a tumor < or = 5 mm had axillary node metastases, compared to 14.7% in those with cancers 6 to 10 mm. The histologic grade and tumor location were also important in predicting nodal positivity. The incidence of positive nodes was 38% in those with poorly differentiated cancers, compared to 8% and 7% in women with well and moderately differentiated cancers, respectively, p = .03. Axillary nodal positivity was seen in 17% of outer quadrant vs 3% of central and inner quadrant primaries, p < .01. The axilla was managed with surgery alone (76%), radiation alone (6%), surgery and radiation (6%), or simply observation (10%). With a median follow-up of 55 months, not one patient has suffered a nodal recurrence, and in our experience, survival free of distant relapse was not adversely affected by the omission of axillary surgery.

Characterization of ligand binding to a carbohydrate-recognition domain of the macrophage mannose receptor

The extracellular portion of the macrophage mannose receptor, an endocytic receptor involved in clearance of glycoconjugates, contains eight domains related to the Ca(2+)-dependent carbohydrate-recognition domains (CRDs) of other C-type animal lectins. The characteristics of ligand binding to an expressed form of one of these CRDs (CRD-4) have been investigated. The expressed domain was found to be a monomer in solution. Results of a solid phase binding assay and a protease resistance assay show that CRD-4 of the mannose receptor undergoes a conformational rearrangement upon binding of Ca2+, correlating with its ability to bind sugar. CRD-4 requires two Ca2+ for sugar binding, even though sequence comparisons with other C-type CRDs suggested that it might bind only one Ca2+. The results are consistent with a ternary complex being formed between CRD-4, sugar, and Ca2+ as is seen in the crystal structure of the CRD of rat mannose-binding protein in complex with an oligosaccharide. The stability of Ca2+ binding is shown to be pH-dependent, a result that is pertinent to release of ligand by the receptor in the endosome. However, CRD-4 retains sugar binding activity at a lower pH than does the whole receptor, suggesting that the conformational change in this CRD alone may not be sufficient to allow release of ligand in the endosomes.

Aggressive concurrent chemoradiotherapy and surgical resection for proximal esophageal squamous cell carcinoma

BACKGROUND

Proximal esophageal cancer has been a disease associated with relatively poor treatment success, partly due to advanced disease at presentation and the morbidity of the surgery required. Therefore, most patients receive palliative radiation therapy, and disease control is poor.

METHODS

Between July 1990 and December 1992, nine consecutive patients with proximal esophageal squamous cell carcinoma were treated with aggressive concurrent chemoradiotherapy followed by surgical resection. Treatment consisted of cisplatin (20 mg/m2/day) and 5-fluorouracil (1000 mg/m2/day), both given as continuous intravenous infusions over 4 days concurrent with accelerated fractionation external beam radiation therapy (150 cGy twice a day to a dose of 2400 cGy). Three weeks after beginning treatment, a second course of chemotherapy and accelerated fractionation radiation therapy was administered to a total preoperative radiation therapy dose of 4500 cGy. After restaging of their disease, patients next underwent surgical resection. A single postoperative course of chemotherapy and 2400 cGy of concurrent accelerated fractionation radiation therapy was administered to those patients with residual tumor in the resection specimen. Two of these nine patients also were given 4-day etoposide infusions (75 mg/m2/day) as part of their chemotherapy and received lower induction radiation therapy doses.

RESULTS

Although significant toxicity was experienced, there were no deaths attributable to the chemoradiotherapy and only one perioperative death. All nine patients underwent surgery; five required pharyngolaryngoesophagectomy. No residual tumor was found in the resection specimen in three of the nine patients. Continuous locoregional tumor control was achieved in all patients. Only two developed distant metastases.

CONCLUSIONS

These results, using aggressive multimodality treatment, suggest that excellent locoregional control and long term, disease free survival can be achieved in selected patients with proximal esophageal cancer.

Management of locally advanced carcinoma of the breast. I. Noninflammatory

BACKGROUND

The treatment of patients with locally advanced noninflammatory breast cancer has evolved substantially over the past 30 years. From 1968 to 1989, 281 women were treated at Mallinckrodt Radiation Oncology Center with four different treatment methods. Median follow-up was 6.2 years (range 3-22 years); no patient was lost to follow-up.

METHODS

Retrospective review of records and analysis of data on a computer file were carried out. Thirty-five patients were treated with irradiation alone, 33 with irradiation and adjuvant chemotherapy, 81 with mastectomy and irradiation, and 132 with mastectomy, irradiation, and chemotherapy (triple-modality).

RESULTS

Actuarial 5- and 10-year disease free survival (DFS) rates were 45% and 36%, respectively, with triple-modality therapy, 31% and 10% with irradiation and chemotherapy, 32% and 19% with irradiation and mastectomy, and 19% and 11% with irradiation alone. Cause specific survival (CSS) paralleled DFS in the four groups. Locoregional tumor control at 5 years was 91% for irradiation, mastectomy, and chemotherapy, 80% for irradiation and mastectomy, 54% for irradiation and chemotherapy, and 31% for irradiation alone. Systemic therapy and/or irradiation given before mastectomy yielded better locoregional tumor control, DFS, and CSS (not statistically significant). No difference in results was noted with radical, modified radical, or total mastectomy. In the triple-modality group, no chest wall failures occurred with chest wall doses greater than 5040 cGy. Grade 2 or higher treatment sequelae were noted in 10-42% of patients, depending on treatment modality.

CONCLUSIONS

Triple-modality therapy yielded improved locoregional tumor control, DFS, and CSS compared with other modalities. Patients treated with surgery had better locoregional tumor control than those who received irradiation alone or in combination with chemotherapy, but the impact on DFS and CSS was less impressive. Additional clinical trials are needed to define further the role and optimal use of the various therapeutic modalities in the management of locally advanced breast cancer.

Management of locally advanced carcinoma of the breast. II. Inflammatory carcinoma

BACKGROUND

Inflammatory carcinoma of the breast has been associated with a poor prognosis. Several therapeutic approaches have been under investigation in an effort to improve outcome.

METHODS

This is a retrospective analysis of 179 patients with histologically confirmed inflammatory carcinoma of the breast: 33 treated with irradiation alone, 35 with combined irradiation and chemotherapy, 25 with irradiation and surgery, and 86 with a combination of three modalities.

RESULTS

The 5-year disease free survival (DFS) rates were 40% for patients treated with three modalities, 24% for those treated with irradiation and surgery, and 6% for those treated with irradiation alone or in combination with chemotherapy without a surgical procedure. The 10-year DFS rates were 35%, 24%, and 0%, respectively. Cause specific survival (CSS) curves closely follow the same trends. A clearly superior locoregional tumor control was observed in patients who underwent a surgical procedure: 79% with three modalities, 76% with irradiation and surgery, and only 30% with irradiation alone or in combination with chemotherapy. Distant metastasis occurred in 57% of the group treated with triple-modality therapy, 60% of those treated with irradiation plus surgery, and 85% of the patients treated with irradiation alone or in combination with chemotherapy. There was no significant correlation between the type of mastectomy or doses of irradiation and locoregional tumor control or survival. The significant morbidity of the trimodal therapy (10%), although somewhat higher than that of other modalities (3.2%), was acceptable.

CONCLUSIONS

The addition of mastectomy to irradiation significantly improved locoregional tumor control, DFS, and CSS; differences were statistically significant. The combination of chemotherapy, surgery, and irradiation had a significant impact on locoregional tumor control and incidence of distant metastases compared with surgery plus irradiation, and a lesser impact, although still statistically significant, on DFS and CSS. Further clinical trials are needed to optimize the management of patients with inflammatory breast cancer.

Endobronchial radiation therapy with or without neodymium yttrium aluminum garnet laser resection for managing malignant airway obstruction

BACKGROUND

Previous reports have shown low-dose-rate (LDR) afterloading Ir-192 endobronchial radiation therapy (EnBRT) to effectively palliate symptoms in patients with malignant airway obstruction. The authors retrospectively assessed the consequences of LDR EnBRT with or without neodymium yttrium aluminum garnet (Nd:YAG) laser resection in 37 patients.

METHODS

Between February 1986 and June 1991, 37 patients with malignant airway obstruction were treated with LDR EnBRT at The Cleveland Clinic Foundation. Inclusion criteria for LDR EnBRT with or without Nd:YAG laser resection were patients with recurrent, symptomatic endobronchial lesions treated previously with external beam irradiation. Of the 37 patients, 21 patients with endobronchial lesions underwent Nd:YAG laser resection; 16 patients with mainly extrinsic lesions received EnBRT only. Before EnBRT, selected patients (7 of 16 in the nonlaser-treatment group and 14 of 21 in the laser-treatment group) received additional external beam treatments of 2000 cGy/10 fractions. The LDR afterloading Ir-192 technique was used to deliver approximately 30 Gy to a 1.0-cm radius target.

RESULTS

All patients had one or more of the following symptoms: 1) dyspnea, 2) fever, 3) cough, and 4) hemoptysis. Good-to-excellent symptom relief was apparent in 16 of 21 (76.2%) laser-treated patients and in 12 of 16 (75%) nonlaser-treated patients. Follow-up bronchoscopy in 28 patients revealed tumor regression in 22 (79%). Median survival time was 16.3 weeks in the laser group and 11.7 weeks in the nonlaser group (P = 0.36). Longer median survival times were noted in laser-treated (22.8 weeks) and nonlaser-treated (16.4 weeks) patients receiving additional external beam treatments. Exsanguination occurred in 7 of 21 (33.3%) laser-treated patients and in 4 of 16 (25%) nonlaser-treated patients. The only factor affecting the exsanguination rate was implant location: 6 of 11 (54.5%) patients had lesions in the right or left upper lobe.

CONCLUSIONS

EnBRT alone or with Nd:YAG laser resection provided good-to-excellent symptom palliation in these patients although a high rate of exsanguination occurred in both groups.

Photon versus fast neutron external beam radiotherapy in the treatment of locally advanced prostate cancer: results of a randomized prospective trial

PURPOSE

To evaluate the effectiveness of fast neutron radiation therapy in treatment of locally advanced carcinomas of the prostate.

METHODS AND MATERIALS

From April 1986 to October 1990, 178 patients were entered on a prospective, multi-institutional randomized study of the NCI-sponsored Neutron Therapy Collaborative Working Group. This trial compared external beam photon irradiation (7000-7020 cGy) with external beam neutron irradiation (2040 ncGy) for patients with high-grade T2 or T3-4, N0-1, M0 adenocarcinomas of the prostate. Eighty-nine patients were randomized to each treatment. Six patients were subsequently judged to be ineligible, leaving 85 photon and 87 neutron randomized patients eligible for analysis.

RESULTS

With a follow-up time ranging from 40 to 86 months (68 months median follow-up) the 5-year actuarial clinical local-regional failure rate for patients treated with neutrons was 11%, vs. 32% for photons (p < 0.01). Incorporating the results of routine posttreatment prostate biopsies, the resulting "histological" local-regional tumor failure rates were 13% for neutrons vs. 32% for photons (p = 0.01). To date, actuarial survival and cause-specific survival rates are statistically indistinguishable for the two patient cohorts, with 32% of the neutron-treated patient deaths and 41% of the photon-treated patient deaths caused by prostate cancer (p = n.s.). Prostate specific antigen (PSA) values were elevated in 17% of neutron-treated patients and 45% of photon-treated patients at 5 years (p < 0.001). Severe late complications of treatment were higher for the neutron-treated patients (11% vs. 3%), and were inversely correlated with the degree of neutron beam shaping available at the participating institutions. Neutron treatment delivery utilizing a fully rotational gantry and multileaf collimator did not result in an increase in severe late effects when compared to photon treatment.

CONCLUSION

High energy fast neutron radiotherapy is safe and effective when adequate beam delivery systems and collimation are available, and it is significantly superior to external beam photon radiotherapy in the local-regional treatment of large prostate tumors.

Age as a prognostic factor for breast and regional nodal recurrence following breast conserving surgery and irradiation in stage I and II breast cancer

PURPOSE

To evaluate the association between age and breast/regional nodal relapse following breast conserving surgery and irradiation.

METHODS AND MATERIALS

The results of treatment in 511 patients with 519 Stage I and II breast cancers treated at Mallinkrodt Institute of Radiology and affiliated hospitals between 1958 and 1988 were reviewed.

RESULTS

Seventy women, of whom 96% had axillary dissections, were 39 years of age or younger. These young patients were more likely to have chemotherapy (p < 0.0001), and tumor bed reexcision (p < 0.01), and less likely to have an undissected axilla (p < 0.01), or estrogen receptor positive tumor (p = 0.02) than the older women (> 40 years). Although breast recurrence tended to appear earlier in the younger patients (12% at 5 years for those < 40 years vs. 6% at 5 years for those older), by 7 years the breast failure rate for the two groups was the same (12%), p = 0.13. In the 37 women 35 years of age or younger, the actuarial rate of breast recurrence was 9% at 7 years. Compared to other series in the literature, in which cancers were grossly excised without regard to the microscopic margins of resection, and reexcision was not routinely performed, young women treated with breast conserving surgery and irradiation at our institution frequently underwent reexcision of the tumor bed (57%), and had negative pathologic margins of resection (75%). Regional nodal relapse was in general uncommon, and not seen with increased frequency in the youngest cohort.

CONCLUSION

Our experience suggests that young age is not a contraindication to breast conserving surgery and irradiation. Although breast cancers in this cohort may have certain features rendering them prone to local failure, we believe this risk can be mitigated by appropriate patient selection and optimal surgical resection.

Survival following breast-conserving surgery and irradiation or modified radical mastectomy in patients with invasive breast cancers with a maximum diameter of 1 cm

The reported relapse-free survival for women with invasive breast cancers measuring no more than 10 mm in dimension ranges from 75% to 95%, with axillary status an important prognostic factor in most series. Further study of prognostic variables in this most favorable subset is notably limited. We retrospectively reviewed the records of 168 women with invasive breast cancers < or = 10 mm treated with either breast conserving surgery+axillary dissection (AXD) and radiation therapy, or mastectomy+AXD. The actuarial survival and survival free of distant metastases (DMFS) at 7 years was 95% and 97%, respectively. Location and size of the primary tumor were most important in predicting outcome, although statistical significance was not achieved. The 5-year distant metastases-free survival (DMFS) was 100% for central and inner quadrant tumors, compared to 97% in those with outer quadrant tumors, p = 0.18. The 5-year DMFS was 100%, 95%, and 98% for patients with cancers 2-5 mm, 6-9 mm, and 10 mm, respectively, p = 0.15. Status of the axillary lymph nodes, type of breast surgery, clinical tumor status (palpable vs. nonpalpable), age, menopausal status, histologic grade, systemic therapy, or histologic type were not found to have a significant impact on prognosis.

Acid, motility, and ulcers: a comparison of cisapride with placebo in the prevention of duodenal ulcer relapse

In a single centre double blind study of 66 patients, the value of cisapride (10 mg twice daily) was compared with placebo in the prevention of duodenal ulcer relapse. Patients who remained ulcer free attended for clinical review every two months and had a mandatory endoscopy at 0, 4, 8, and 12 months or if symptoms suggestive of ulcer recurrence developed. The 12 month crude relapse rates (that underestimate the probability of ulcer recurrence) showed that cisapride was superior to placebo (34% (11/32) relapsed on cisapride v 68% (23/34) on placebo, p = 0.007). This finding was confirmed using lifetable analysis, with a 35% reduction (95% confidence intervals 10-59%, p < 0.05) in the proportion of ulcer relapses in patients who had received cisapride compared with those treated with placebo. These results are similar to those reported in maintenance trials of H2 receptor antagonists analysed by the same method. Drug related adverse clinical events were mainly trivial, but led to three patients on cisapride and one on placebo withdrawing from the trial.

Organizational factors and the perception of motion in depth

When two stationary, stereoscopically separated targets are viewed in a completely dark surround, and no cues concerning their egocentric distances from the observer are salient, the farther target tends to be seen at the same distance it would have assumed if it were by itself. The nearer target is seen as being closer than it would have been if seen alone. The present studies extend this previous finding (now termed the far-anchor effect) into the domain of targets that move in stereoscopic space. Observers viewed two small illuminated targets, which began at either the same or different stereoscopic distances. One of the targets was moved in depth and the observers identified the target that appeared to move. Conditions varied according to the initial depth location of the moving target. Significantly more correct responses were reported when the nearer target moved than when the farther one moved, consistent with the hypothesis that the perception of motion in depth is affected by the aforementioned perceptual anchoring effect of the farther target.

Regional nodal management and patterns of failure following conservative surgery and radiation therapy for stage I and II breast cancer

PURPOSE

To determine the incidence, pattern of regional nodal failure, and treatment sequelae as determined by the extent of lymphatic irradiation.

METHODS AND MATERIALS

The records of 511 patients with 519 Stage I and II breast cancers treated with breast conserving surgery with or without axillary dissection and irradiation were reviewed. The extent of nodal irradiation was at the discretion of the attending radiation oncologist and varied considerably over the years. Management of the axilla consisted of axillary dissection alone in 351, axillary dissection and supplemental irradiation in 74, irradiation alone in 75, and simply observation in 21 patients.

RESULTS

Overall, axillary recurrence was uncommon (1.2%), but was slightly more frequent after irradiation alone (2.7%) than after surgery alone (0.3%), p = 0.14. There was no benefit for supplemental axillary irradiation after an axillary dissection yielding negative or 1 to 3 positive nodes. In the 21 patients in whom the axilla was observed, axillary recurrence was not observed. Supraclavicular failures were rare in women with negative or 1 to 3 positive axillary lymph nodes (0.5%), and not significantly affected by elective irradiation. Internal mammary node recurrence was seen in only one patient, and was not significantly influenced by elective internal mammary irradiation. Both arm and breast edema were significantly more common in women having breast and nodal irradiation than after breast irradiation alone. These sequelae were not influenced significantly by the number of lymph nodes obtained in the axillary dissection specimen. Radiation pneumonitis was seen with increased frequency with more extensive nodal radiotherapy. Pneumonitis was not found to be affected by the administration or sequencing of chemotherapy.

CONCLUSION

There is little justification for axillary or supraclavicular irradiation following an axillary dissection which yields negative or minimally involved (1 to 3 positive) lymph nodes. There were too few patients with extensive axillary node metastases (> or = 4 positive) in our series to draw conclusions about the optimal extent of nodal irradiation in this subset. Elective internal mammary lymph node irradiation increases technical complexity, does not appear to be advantageous, and when combined with supraclavicular irradiation places the patient at highest risk for pneumonitis.

Structural requirements for high affinity binding of complex ligands by the macrophage mannose receptor

The mannose receptor of macrophage and hepatic endothelial cells discriminates between endogenous and exogenous sugar-bearing structures. Previous competition studies have indicated that the receptor binds the monosaccharides mannose, fucose, and N-acetylglucosamine but displays much higher affinity for multivalent oligosaccharides, such as those found on the surface of potentially pathogenic microorganisms. The hydrodynamic properties of the receptor have been examined, revealing that the receptor is a monomer. This result suggests that multiple carbohydrate recognition domains (CRDs) in the extracellular domain of a single receptor polypeptide cooperate to achieve high affinity binding of complex ligands. In order to determine the importance of individual CRDs, properties of receptor segments containing groups of CRDs expressed in insect cells have been examined. The results indicate that two of the CRDs (4 and 5) form a protease-resistant, ligand-binding core but that five CRDs in tandem (4-8) are required to match the affinity of the intact receptor for yeast mannan. A consequence of the organization of the receptor is that both valency and geometry of glycoconjugates are important determinants of binding affinity.

Expression and purification of the cytoplasmic tail of an endocytic receptor by fusion to a carbohydrate-recognition domain

Gene fusion has been used to produce the cytoplasmic domain of an endocytic receptor. DNA sequences coding for the 52 COOH-terminal amino acids of the mannose receptor from human macrophages, including the 41-amino acid cytoplasmic tail, were fused to the codons specifying the carbohydrate-recognition domain (CRD) of rat mannose-binding protein. The fusion protein was expressed in Escherichia coli and purified in one step on mannose-Sepharose, making use of the carbohydrate-binding activity of the CRD. The tail peptide was released from the fusion protein using endoproteinase Arg-C. This method provides an alternative to chemical synthesis for the production of midlength peptides.

Endemic human T cell lymphotropic virus type II infection among isolated Brazilian Amerindians

Evidence for human T cell lymphotropic viruses (HTLV) was sought in sera and cells collected from adults in 13 isolated South and Central American Indian tribes. Serologic tests identified frequent HTLV-II-like reactivity among the Cayapo and Kraho tribes, who live 330 km apart in Central Brazil. Polymerase chain reaction analyses of viral DNA in cell pellet and plasma fractions confirmed the virus as HTLV-II. Both tribes speak Gé and, at the time of blood collection (1974), subsisted as hunter/gatherers and slash and burn agriculturalists. Further testing of plasma from Cayapo and Kraho of all ages revealed overall HTLV-II prevalence rates of 33.3% and 12.2%, respectively, with increasing prevalence associated with age and female gender. These data reveal for the first time a high prevalence of HTLV-II infection in remote South American Indians with little contact with non-Indians. Thus, HTLV-II is postulated to be an ancient human virus in the New World.

Contribution to ligand binding by multiple carbohydrate-recognition domains in the macrophage mannose receptor

The extracellular portion of the macrophage mannose receptor is composed of several cysteine-rich domains, including a fibronectin type II repeat and eight segments related in sequence to Ca(2+)-dependent carbohydrate-recognition domains (CRDs) of animal lectins. Expression of portions of the receptor in vitro, in fibroblasts and in bacteria, has been used to determine which of the extracellular domains are involved in binding and endocytosis of ligand. The NH2-terminal cysteine-rich domain and the fibronectin type II repeat are not necessary for endocytosis of mannose-terminated glycoproteins. CRDs 1-3 have at most very weak affinity for carbohydrate, so the carbohydrate binding activity of the receptor resides in CRDs 4-8. CRD 4 shows the highest affinity binding and has multispecificity for a variety of monosaccharides. However, CRD 4 alone cannot account for the binding of the receptor to glycoproteins. At least 3 CRDs (4, 5, and 7) are required for high affinity binding and endocytosis of multivalent glycoconjugates. In this respect, the mannose receptor is like other carbohydrate-binding proteins, in which several CRDs, each with weak affinity for single sugars, are clustered to achieve high affinity binding to oligosaccharides. In the mannose receptor, these multiple weak interactions are achieved through several active CRDs in a single polypeptide chain rather than by oligomerization of polypeptides each containing a single CRD.

Evolutionary conservation of intron position in a subfamily of genes encoding carbohydrate-recognition domains

The structure of the gene encoding a chicken liver receptor, the chicken hepatic lectin, which mediates endocytosis of glycoproteins has been established. The coding sequence is divided into six exons separated by five introns. The first three exons correspond to separate functional domains of the receptor polypeptide (cytoplasmic tail, transmembrane sequence, and extracellular neck region), while the final three exons encode the Ca(2+)-dependent carbohydrate-recognition domain. These results, as well as computer-assisted multiple sequence comparisons, establish this receptor as the evolutionary homolog of the mammalian asialoglycoprotein receptors. It is interesting that the chicken receptor falls into a subfamily of proteins along with the mammalian asialoglycoprotein receptors, since the saccharide-binding specificity of the chicken receptor resembles more closely that of a different set of calcium-dependent animal lectins, which includes the mannose-binding proteins. The portions of the genes encoding the carbohydrate-recognition domains of these proteins lack introns. The results suggest that divergence of intron-containing and intron-lacking carbohydrate-recognition domains preceded shuffling events in which other functional domains were associated with the carbohydrate-recognition domains. This was followed by further divergence, generating a variety of saccharide-binding specificities.

Species-specific diversity among simian immunodeficiency viruses from African green monkeys

The prevalence, natural history, and genetic characteristics of simian immunodeficiency virus (SIV) infections in most feral African monkey species are presently unknown, yet this information is essential to elucidate their origin and relationship to other simian and human immunodeficiency viruses. In this study, a combination of classical and molecular approaches were used to identify and characterize SIV isolates from West African green monkeys (Cercopithecus sabaeus) (SIVagm isolates). Four SIVagm viruses from wild-caught West African green monkeys were isolated and analyzed biologically and molecularly. Amplification, cloning, and sequencing of a 279-bp polymerase fragment directly from uncultured peripheral blood mononuclear cells was facilitated by the use of nested polymerase chain reaction. The results indicated that West African green monkeys are naturally infected with SIVs which are closely related to East African SIVagm isolates. However, structural, antigenic, and genetic differences were observed which strongly suggest that the West African green monkey viruses comprise a phylogenetically distinct subgroup of SIVagm. These findings support our previous hypothesis that SIVagm viruses may have evolved and diverged coincident with the evolution and divergence of their African green monkey host. In addition, this study describes a polymerase chain reaction-based approach that allows the identification and molecular analysis of divergent SIV strains directly from primary monkey tissue. This approach, which does not depend on virus isolation methods, should facilitate future studies aimed at elucidating the origins and natural history of SIVs in feral African green monkey populations.

Disturbed gastroduodenal motility in patients with active and healed duodenal ulceration

Disordered gastroduodenal motility may promote duodenal ulceration by allowing prolonged acid contact with the duodenal mucosa. Using a multilumen perfused catheter incorporating 3 pH microelectrodes, antral and duodenal pH and antropyloroduodenal pressure activity were recorded in 36 subjects (10 with healed duodenal ulceration, 11 with active duodenal ulceration, and 15 healthy volunteers) during fasting and after a radiolabeled solid test meal. Correct pH probe/catheter position was continuously verified by recording transmucosal potential difference across the pylorus. Patients with active and healed duodenal ulcer had similarly disordered gastroduodenal motility. The chief abnormalities consisted of an increase in postprandial duodenal retroperistalsis (healed duodenal ulceration, 12 +/- 1 events per hour; active duodenal ulceration, 12 +/- 1; control, 6 +/- 1; mean +/- SEM: healed and active duodenal ulceration vs. control, P = 0.004 and P = 0.03, respectively), a reduction in pressure waves sweeping aborally through the duodenum after the meal (healed duodenal ulceration, 22 +/- 4 events per hour; active duodenal ulceration, 23 +/- 3; control, 34 +/- 4: healed and active duodenal ulceration vs. control, P = 0.04 and P less than 0.05, respectively), and an increased incidence of atypical, complex forms of coordinated duodenal motor activity throughout the study (postprandial data; healed duodenal ulceration, 8 +/- 1 events per hour; active duodenal ulceration, 10 +/- 1; control, 4 +/- 1: healed and active duodenal ulceration vs. control, P = 0.02 and P less than 0.02, respectively). In addition, gastric emptying of the solid test meal was significantly delayed in healed, but not active, duodenal ulceration [half-emptying time, healed duodenal ulceration 185 minutes (117-235); active duodenal ulceration 102 minutes (80-200); control 107 minutes (78-130): healed duodenal ulceration vs. control, P less than 0.009]. Duodenal bulb pH was similar in controls and patients with active duodenal ulceration; however, bulb pH was less than 4 for a significantly greater period of time in healed duodenal ulceration compared with active ulcer patients, particularly after the meal. In conclusion, duodenal ulcer disease is associated with disturbed gastroduodenal motility, even when the ulcer is quiescent and when intraduodenal acidity is low. In healed duodenal ulceration, disturbed motility may promote ulcer relapse by impairing acid clearance from the bulb. However, in active ulceration other factors such as mucosal bicarbonate secretion may have a more influential role in determining intraduodenal pH.

Selective decontamination of the gastrointestinal tract as an infection control measure

An outbreak caused by a Klebsiella aerogenes resistant to ceftazidime, cefuroxime, cefotaxime, ampicillin and piperacillin and sensitive to aminoglycosides, imipenem and temocillin occurred in a teaching hospital's busy multi-disciplinary Intensive Care Unit over a 3-month period. Four patients had bacteraemia and a further four were colonized. Traditional infection control measures failed to eradicate the outbreak. The introduction of a selective gastrointestinal decontamination regimen consisting of tobramycin, amphotericin and colistin as a gel to the oropharynx, nose and rectum and a suspension via a nasogastric tube resulted in rapid disappearance of the outbreak strain with no new isolates being detected clinically or in surveillance specimens over an 8-week period.

Carbohydrate-recognition domains as tools for rapid purification of recombinant eukaryotic proteins

Methods have been developed for expression and purification of eukaryotic proteins by creating fusions with the carbohydrate-recognition domain (CRD) of the galactose-specific rat hepatic lectin. In order to generate the fusion proteins, vectors have been constructed so that cDNAs for passenger proteins can be inserted in any reading frame following a segment of DNA encoding the CRD. The feasibility of using this approach as an aid to protein purification has been demonstrated using human placental alkaline phosphatase. Following expression in either of two different eukaryotic expression systems, the CRD-phosphatase fusion protein can be isolated by one step of affinity chromatography on galactose-Sepharose under mild, non-denaturing conditions. Incorporation of a proteinase-sensitive linker allows cleavage of the CRD from the passenger protein. Immobilised proteinase could be rapidly separated from the cleavage products and the released, active phosphatase was purified away from the CRD by re-chromatography on galactose-Sepharose. These methods provide a means of isolating correctly folded recombinant eukaryotic proteins when cDNAs are available, but the properties of the encoded proteins are unknown.

Primary structure of the mannose receptor contains multiple motifs resembling carbohydrate-recognition domains

Macrophages express a cell surface receptor which mediates phagocytosis and pinocytosis of particles and solutes containing mannose (fucose and N-acetylglucosamine are also ligands for the receptor). An apparently identical protein has been isolated from human placenta. Proteolytic fragments of the placental receptor were sequenced so that oligonucleotide probes complementary to the receptor cDNA could be generated. These probes were used to isolate cDNA clones covering the entire coding portion of the mRNA for the receptor. Confirmation that these clones encode the mannose receptor was obtained by expression in rat fibroblasts. The expressed protein mediates uptake and degradation of mannose-conjugated serum albumin. The deduced amino acid sequence of the receptor reveals that it is most likely to be a type I transmembrane protein (COOH terminus on the cytoplasmic side of the membrane) since the mature polypeptide is preceded by a signal sequence and a hydrophobic stop transfer sequence is located 45 amino acids from the COOH terminus. The extracellular portion of the receptor polypeptide consists of three types of domains. The first 139 amino acids constitute a cysteine-rich segment which does not resemble other known sequences. There follows a domain which closely resembles fibronectin type II repeats. The remainder of the extracellular portion of the receptor is composed of eight segments homologous with the C-type carbohydrate-recognition domains of the asialoglycoprotein receptor, mannose binding proteins, and other Ca2(+)-dependent animal lectins. This structure suggests that the receptor may contain multiple ligand-binding domains thus accounting for its tight binding to highly multivalent ligands.

Uptake and processing of glycoproteins by isolated rat hepatic endothelial and Kupffer cells

Mannose-(Man) and N-acetylglucosamine- (GlcNAc)-terminated glycoproteins are cleared from blood by carbohydrate-specific receptors present on both hepatic endothelial and Kupffer cells. It is not known whether the same receptors are present on each cell type or the relative contributions to glycoprotein metabolism made by Kupffer and endothelial cells. Here we report experiments where data from glycoprotein metabolism by purified populations of isolated rat hepatic endothelial and Kupffer cells have been analyzed by mathematical modelling and parameter estimation. Kupffer cells had significantly higher binding rate constants (k'21) than endothelial cells for agalactoorosomucoid (AGOR) and hyaluronidase, but lower k12 ('off-rate') indicating that Kupffer cells had higher affinities for Man/GlcNAc-terminated glycoproteins than endothelial receptors. Furthermore, although endothelial cells had similar affinities (k'21 and k12) for AGOR and hyaluronidase, the 'off-rate' of Kupffer cells was significantly greater for AGOR than for hyaluronidase, indicating that Kupffer cell receptors have lower affinity for AGOR. Internalization and ligand catabolic rates also differed between the two cell types. The data indicate that Kupffer and endothelial cells appear to have different Man/GlcNAc receptors and that the destination of a glycoprotein and its subsequent processing is determined by the structure of a glycoprotein's oligosaccharide.

Structure and evolutionary origin of the gene encoding a human serum mannose-binding protein

The N-terminal sequence of the major human serum mannose-binding protein (MBP1) was shown to be identical at all positions determined with the amino acid sequence predicted from a cDNA clone of a human liver MBP mRNA. An oligonucleotide corresponding to part of the sequence of this cDNA clone was used to isolate a cosmid genomic clone containing a homologous gene. The intron/exon structure of this gene was found to closely resemble that of the gene encoding a rat liver MBP (MBP A). The nucleotide sequence of the exons differed in several places from that of the human cDNA clone published by Ezekowitz, Day & Herman [(1988) J. Exp. Med. 167, 1034-1046]. The MBP molecule comprises a signal peptide, a cysteine-rich domain, a collagen-like domain, a 'neck' region and a carbohydrate-binding domain. Each domain is encoded by a separate exon. This genomic organization lends support to the hypothesis that the gene arose during evolution by a process of exon shuffling. Several consensus sequences that may be involved in controlling the expression of human serum MBP have been identified in the promoter region of the gene. The consensus sequences are consistent with the suggestion that this mammalian serum lectin is regulated as an acute-phase protein synthesized by the liver.

Duodenal bulb acidity and the natural history of duodenal ulceration

Fasting and post-prandial duodenal bulb pH was recorded in 10 subjects with untreated duodenal ulcers (DU), 10 subjects with healed DU, and 15 healthy volunteers. During fasting, pH was less than 4 for a greater percentage of time in healed than in active DU. Ingestion of a solid test meal accentuated this difference: subjects with active DU and controls both showed less bulb acidification than subjects with healed ulcers. Bulb pH was similar in patients with active ulceration and controls. The finding of neutral bulb pH with active ulceration and low bulb pH with healing may explain the typical cycle of spontaneous healing and relapse in duodenal ulcer disease.

Characterisation of antibodies to urinary gonadotrophin peptide

There is now general recognition that human chorionic gonadotropin (hCG), its beta subunit and its fragments are valuable diagnostic markers of trophoblastic and some non-trophoblastic malignancies. Urinary gonadotropin peptide (UGP) contains at least one epitope which cross-reacts with the beta-subunit of hCG. In order to assess the potential of UGP as a tumour marker in its own right, it was paramount that any measurements made could be regarded as specific for UGP and not cross-reactive with either hCG or human luteinising hormone (hLH). Four antibodies were tested, two polyclonal (AK12 and DR-Pool) and two monoclonal (2C2 and 6D3). Initial screening using radioiodinated (125I) UGP, hCG, hCG beta-subunit and hLH showed that the polyclonal antibodies bound to all four gonadotrophins, whilst the monoclonal antibodies bound only to the radioiodinated UGP. The antibodies were tested in both radioimmunoassay (RIA) and immunoradiometric assay (IRMA-sandwich assay) systems. The parameters measured were sensitivity and specificity for UGP. The polyclonal antibodies used in the RIA system produced a sensitive assay (0.2 ng/ml UGP) which was relatively specific; cross-reactions for the AK12 antibody (at 50% inhibition) were 5% for hCG, 11% for its beta-subunit, 0.4% for the alpha-subunit and 2.6% for hLH. The monoclonal antibodies performed optimally in the IRMA system. Immobilised 2C2 and radiolabelled (125I) AK12 produced a system that had a sensitivity of 0.4 ng/ml UGP and cross-reactivity (50% maximum binding) of 2% for the hCG beta-subunit and less than 1% for hCG, hLH and the hCG alpha-subunit.