Risk factors for fracture by same-level falls among workers across sectors: a cross-sectional study of national open database of the occupational injuries in Japan.

OBJECTIVES: The hospitalisation rate for work-related injuries among older workers is double that of younger workers; however, the risk factors for same-level fall fractures sustained during industrial accidents remain unclear. This study aimed to estimate the influence of worker age, time of day and weather conditions on the risk of same-level fall fractures in all industrial sectors in Japan. STUDY DESIGN: This was a cross-sectional study. METHODS: This study used the population-based national open database of worker death and injury reports in Japan. In total, 34,580 reports of occupational same-level falls between 2012 and 2016 were used in this study. Multiple logistic regression analysis was performed. RESULTS: In primary industries, workers aged ≥55 years had a 1.684 times greater risk of fracture (95% confidence interval [CI]: 1.167-2.430) compared with workers aged ≤54 years. In tertiary industries, relative to the odds ratio (OR) of injuries recorded at 0:00-2:59 a.m., the ORs recorded at 6:00-8:59 p.m., 6:00-8:59 a.m., 9:00-11:59 p.m. and 0:00-2:59 p.m. were 1.516 (95% CI: 1.202, 1.912), 1.502 (95% CI: 1.203-1.876), 1.348 (95% CI: 1.043-1.741) and 1.295 (95% CI: 1.039-1.614), respectively. The risk of fracture increased with a 1-day increase in the number of snowfall days were per month in secondary (OR = 1.056, 95% CI: 1.011-1.103) and tertiary (OR = 1.034, 95% CI: 1.009-1.061) industries. The risk of fracture decreased with every 1-degree increase in the lowest temperature in primary (OR = 0.967, 95% CI: 0.935-0.999) and tertiary (OR = 0.993, 95% CI: 0.988-0.999) industries. CONCLUSIONS: With the increasing number of older workers and changing environmental conditions, the risk of falls in the tertiary sector industries is increasing, particularly just before and just after shift change hours. These risks may be associated with environmental obstacles during work migration. It is also important to consider the weather-associated risks of fracture.

Evaluation of genetic factors involved in nocturnal electromyographic activity of masticatory muscles in twins.

OBJECTIVES: The objectives of this study were to assess sleep bruxism events by directly recording electromyographic activity during sleep and to reveal the relative importance of genetic and environmental factors involved in sleep bruxism in twins. MATERIAL AND METHODS: The subjects consisted of 108 twins (mean age 22.2 ± 6.4 years). Electromyographic activity of temporalis muscles during sleep was evaluated using a portable automatic sleep bruxism analyzer (Grindcare 3.0, Medotech A/S), and recordings were carried out for at least three consecutive nights. Quantitative genetic statistics based on structural equation modeling was utilized to estimate variance components. RESULTS: Monozygotic twin-pair correlation for the number of nocturnal electromyographic activities recorded in this study (r = 0.463, P = 0.009) was higher than dizygotic twin-pair correlation (r = 0.103, P = 0.725). The proportion of total phenotypic variance in the liability of sleep bruxism to attribute to genetic influences, related to the electromyographic activities, was 48 % (95 % CI 17-95 %) and to unique environmental influences was 52 % (95 % CI 28-82 %). CONCLUSIONS: Additive genetic effects may be a contributing factor to the occurrence of nocturnal EMG activity associated with sleep bruxism. CLINICAL RELEVANCE: A greater understanding of the contribution of genetic factors could have beneficial uses, including enhanced accuracy of sleep bruxism diagnosis, management of sleep bruxism, and enhanced estimation of the prognosis for patients suffering from sleep bruxism. In addition, it could be also important to adequately evaluate the environmental factors in patients with sleep bruxism.

Influence of genetic and environmental factors on oral diseases and function in aged twins.

This study was conducted to quantify the genetic and environmental contributions to oral disease and function in twins. Participants were middle-aged and old twins, 116 monozygotic and 16 dizygotic pairs whose mean age was 66·1 ± 10·3 (SD) years. Number of teeth, percentage of decayed, filled and missing teeth and periodontal status were recorded as indicators of oral disease. The widths of upper and lower dental arch served as indicators of morphological figures. Furthermore, stimulated salivary flow rate, occlusal force and masticatory performance were measured as indicators of oral function. Univariate genetic analysis with monozygotic and dizygotic twin pairs was conducted to detect the fittest structural equation model of each outcome. Both number of teeth and periodontal status fitted the model composed of common environmental factor and unique environmental factor. Decayed, filled and missing teeth, morphological figures and measurements of oral function fitted the model composed of additive genetic factor and unique environmental factor. The model fitting of each measurement suggested that periodontal disease was mainly affected by environmental factors, while morphological figures and oral functions were influenced by both genetic and environmental factors.

Impact of eating rate on obesity and cardiovascular risk factors according to glucose tolerance status: the Fukuoka Diabetes Registry and the Hisayama Study.

AIMS/HYPOTHESIS: Medical nutrition therapy plays a critical role in the prevention and treatment of type 2 diabetes. However, appropriate measures of eating behaviours, such as eating rate, have not yet been clearly established. The aim of the present study was to examine the associations among eating rate, obesity and cardiovascular risk factors. METHODS: A total of 7,275 Japanese individuals aged ≥40 years who had normal fasting glucose levels, impaired fasting glucose or diabetes were divided into four groups according to self-reported eating rate: slow, medium, relatively fast and very fast. The associations between eating rate and various cardiovascular risk factors were investigated cross-sectionally. RESULTS: The proportions of participants who were obese or who had elevated waist circumference levels increased progressively with increases in eating rate (p for trend <0.001), regardless of glucose tolerance status. These associations remained significant after adjustment for potential confounders, namely, age, sex, total energy intake, dietary fibre intake, current smoking, current drinking and regular exercise (p for trend <0.001). Blood pressure and lipid levels also tended to increase in association with eating rate. HbA(1c) rose significantly as eating rate increased, even after multivariate adjustment, including BMI, in diabetic patients on insulin therapy (p = 0.02), whereas fasting plasma glucose did not increase significantly. CONCLUSIONS/INTERPRETATION: Our findings suggest that eating rate is associated with obesity and other cardiovascular risk factors and therefore may be a modifiable risk factor in the management of cardiovascular risk factors and diabetes.

Onco-testicular sperm extraction: testicular sperm extraction in azoospermic and very severely oligozoospermic cancer patients.

An increased risk of testicular cancer in men with infertility and poor semen quality has been reported. In view of the high cure rates for testicular germ cell tumours, increasing clinical importance is being placed on the protection of fertility. High-dose cytostatic therapy may be expected to cause long-term infertility. Thus, the standard procedure for fertility protection is the cryopreservation of ejaculated spermatozoa or testicular tissue before therapy. Four male patients with azoospermia and two patients with very severe oligozoospermia underwent onco-testicular sperm extraction (TESE). We attempted onco-TESE in patients with azoospermia and very severe oligozoospermia after orchiectomy. Of the patients with testicular germ cell tumours, four had spermatozoa in their testicular tissues. Sertoli cell-only syndrome was found in one patient, and one patient showed maturation arrest without the detection of spermatozoa. Three of six showed seminomatous germ cell tumour, two of six had nonseminomatous germ cell tumour and one patient showed no malignancy. Two patients achieved clinical pregnancy. Fertility challenges in men with cancer are the most straightforward because of the relative ease of obtaining and cryopreserving sperm. Testicular sperm extraction is a useful technique for obtaining spermatozoa before cytotoxic therapy in azoospermic and very severely oligozoospermic cancer patients.

Growth regulation of human melanocytes: mitogenic factors in extracts of melanoma, astrocytoma, and fibroblast cell lines.

Melanocytes derived from fetal or adult skin do not propagate in vitro unless cultured in the presence of factors such as 12-O-tetradecanoylphorbol 13-acetate (TPA). In a search for physiological factors regulating the growth of melanocytes, extracts of various cultured cell types were tested. Factors produced by melanoma and astrocytoma cell lines support continued proliferation of melanocytes in the absence of TPA. WI-38, a fibroblast cell line derived from human embryonic lung, was the most active source of melanocyte growth factors. No melanocyte growth-promoting activity was found in extracts of cultured neuroblastoma, renal cancer, normal keratinocytes, or renal epithelium. Nerve growth factor, epidermal growth factor, melanocyte-stimulating hormone, transforming growth factor-beta, and platelet-derived growth factor did not have growth-promoting activity for melanocytes. The presence of melanocyte growth factors and TPA together resulted in the strongest mitogenic activity for melanocytes, permitting the recovery (at 20 days) of 4 to 20 times as many cells as in growth factor or TPA alone.

Renal histology before and after effective enzyme replacement therapy in a patient with classical Fabry's disease.

A 38-year-old man underwent renal biopsy because of proteinuria. It revealed swelling and vacuolation of glomerular epithelial cells, as well as myelin-like structures characteristic of Fabry's disease. Detection of decreased plasma activity of alpha-galactosidase A confirmed the diagnosis. Enzyme replacement therapy was provided with recombinant agalsidase-beta, resulting in improvement of his symptoms. When renal biopsy was repeated, specific staining for globotriaosylceramide showed that renal deposits were decreased by enzyme therapy.

[Diaphragmatic hernia 3 years after the nephrectomy].

A 81-year-old man was referred to our department for the acute onset of dyspnea. Chest radiograph suggested a bowel shadow containing gases in the right chest. Computed tomography (CT) scan revealed the dislocation of the liver and the transverse colon in the right pleural cavity. Although the patient had no history of a blunt trauma, he had undergone the right nephrectomy for the renal cancer 3 years before. An emergency operation revealed the right lobe of the liver and the transverse colon profoundly entering into the right pleural cavity. The dislodged organs were gently restored through a dual approach, and the defect of the diaphragm was repaired with a prosthesis. The postoperative course was satisfactory. A diaphragmatic hernia sometimes occurs acutely and often shows life-threatening symptoms. The occurrence of the diaphragmatic hernia associated with previous surgery must be taken into account, when the procedure involved the diaphragm.

Thermus thermophilus TMY isolated from silica scale taken from a geothermal power plant.

AIMS: To identify an extreme thermophile, strain TMY, isolated from silica scale from the geothermal electric power plant and to examine microdiversity of Thermus thermophilus strains. MATERIALS AND RESULTS: The isolated strain TMY was identified by morphological, biochemical and physiological tests. Phylogenetic comparison of the strain and other Thermus strains with 16S rDNA analysis, RAPD and ERIC-PCR fingerprinting were performed. Strain TMY was closely related to strain which was isolated from a hot spring in New Zealand and shown to belong to the Japanese Thermus cluster. However, there were considerable genetic differences between strain TMY and other Thermus species using DNA fingerprinting. CONCLUSIONS: Based on morphological, physiological and genetic properties, strain TMY could be a strain of T. thermophilus. The distinct properties of strain TMY suggest that microdiversity of T. thermophilus strains should be considered. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study have demonstrated genetic diversity within T. thermophilus strains, which were previously masked by an almost identical 16S rDNA sequence. RAPD and ERIC-PCR could be potential methods for distinguishing between Thermus strains.

Twelve-year follow-up of chronic pain in twins: Changes in environmental and genetic influence over time.

BACKGROUND: While genetic influences on chronic pain have been repeatedly demonstrated, we do not know whether these effects are stable or dynamic over time. AIMS: To determine the temporal pattern of genetic and environmental effects to individual differences in chronic pain over 12 years, we use a sample of n = 961 female twins. METHODS: Data on chronic pain were collected in 2004 (T1) and 2016 (T2) using the same comprehensive body map which divides the body into 31 distinct anatomical areas. Multivariate twin analyses for repeated measures were conducted to track changes in genetic and environmental influences. RESULTS: Heritability for chronic pain was 63% at baseline and 55% at follow-up. The best-fitting AE Cholesky model revealed one genetic factor explaining 62% of variance in chronic pain at T1 and 11% at T2. No additional genetic factors explaining the variance in chronic pain at T2 could be detected. Furthermore, a unique environmental factor (E1) explaining 37% of the variance in chronic pain at T1 and 12% at T2 and an additional environmental factor (E2) explaining 77% of the variance at T2 were found. CONCLUSION: We demonstrate for the first time that the same genetic influences are operative over time and that novel environmental factors are important in pain maintenance. The findings highlight the value of more in depth exploration of these non-shared environmental influences that could provide clues to the mechanisms behind remittance and/or maintenance of chronic pain. The identification of important environmental influences could point to novel therapeutic interventions in future. SIGNIFICANCE: The variability in chronic pain is mainly explained by new environmental factors influencing incidence, aggravation and/or chronic pain remission. Integration of these findings may provide a useful conceptual framework for the treatment and prevention of pain and pain chronification.

Functional results of intersphincteric resection for low rectal cancer.

BACKGROUND: Intersphincteric resection (ISR) is the ultimate sphincter-preserving operation for very low rectal cancer. The aim of this study was to assess defaecatory function after ISR in relation to the degree of resection of the internal anal sphincter. METHODS: Between 2001 and 2003, 35 consecutive patients with low rectal cancer had curative ISR, categorized as total, subtotal or partial resection of the internal anal sphincter. Defaecatory function was assessed in terms of frequency of bowel movements and continence. Sphincter function was evaluated by manometric study and anorectal sensation testing before surgery and 3, 6 and 12 months afterwards. RESULTS: Defaecatory function was satisfactory after ISR; 34 of 35 patients were grossly continent. The maximum resting anal canal pressure fell after all three procedures. Patients who had total ISR had reduced anal canal sensation at 3 months, but this had improved by 12 months after surgery. CONCLUSION: These functional results suggest that ISR should be considered as an alternative to abdominoperineal resection for low rectal cancer. However, as the outcome for continence is worse after total ISR than subtotal or partial ISR, the indication for total ISR should strictly take into account the preoperative sphincter function.

Signaling pathways regulating IL-1alpha-induced COX-2 expression.

Interleukin-1alpha(IL-1alpha) stimulates the production of prostaglandin E(2) (PGE(2)) in odontogenic keratocyst fibroblasts. However, the signaling pathways remain obscure. In this study, we investigated IL-1alphasignaling pathways that regulate cyclooxygenase-2 (COX-2) expression in odontogenic keratocyst fibroblasts. IL-1alphaincreased the expression of COX-2 mRNA and protein, and PGE(2) secretion in the fibroblasts. IL-1alphaincreased the phosphorylation of extracellular signal-regulated protein kinase-1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK). PD-98059, SB-203580, SP-600125, and PDTC-which are inhibitors of ERK1/2, p38, JNK, and nuclear factor-kappaB (NF-kappaB), respectively-attenuated the IL-1alpha-induced COX-2 mRNA expression and activated protein kinase C PGE(2) secretion. IL-1alpha(PKC), and PKC inhibitor staurosporine inhibited IL-1alpha-induced phosphorylation of ERK1/2, p38, and JNK, and decreased IL-1alpha-induced COX-2 mRNA expression. Thus, in odontogenic keratocyst fibroblasts, IL-1alphamay stimulate COX-2 expression both through the PKC-dependent activation of ERK1/2, p38, and JNK signaling pathways, and through the NF-kappaB cascade.

Female sexual pain: Epidemiology and genetic overlap with chronic widespread pain.

BACKGROUND: Increased tender spots and lowered general pain thresholds have been observed in patients with dyspareunia. Based on this, the aim of the study was to compare the co-occurrence of female sexual pain across various pain populations and to further explore the aetiological structure underlying sexual pain by dissecting the genetic and environmental covariation among sexual pain, chronic widespread pain (CWP) and the previously reported psychological correlates of anxiety sensitivity and depression. METHODS: A multivariate twin study including 1489 female twin individuals (246 full MZ pairs, 187 full DZ pairs and 623 whose co-twin did not participate). Main outcomes measures included self-reported diagnosis of osteoarthritis and rheumatoid arthritis, and validated questionnaires for the assessment of sexual pain, CWP, depression and anxiety sensitivity. RESULTS: Sexual pain showed a small but statistically significant correlation with CWP (r = 0.08; p < 0.05), anxiety sensitivity (r = 0.15, p < 0.001) and depression (r = 0.09, p < 0.01). The heritability of sexual pain was found to be 31%. Multivariate variance component analysis revealed a genetic factor common among CWP, depression, anxiety sensitivity and sexual pain, and a second genetic factor shared between anxiety sensitivity and sexual pain only. We further detected genetic and environmental factors unique to sexual pain, explaining 24.01% and 67.24%, respectively, of the phenotypic variance. CONCLUSIONS: Our findings suggest some overlap between sexual pain and CWP and point towards a shared but complex psychophysiological aetiology underlying sexual pain. Results further highlight the influence of specific environmental and contextual stressors in the development and maintenance of sexual pain. SIGNIFICANCE: Sexual pain shares a common genetic aetiology with chronic widespread pain and the frequently reported psychological comorbidities of depression and anxiety. Overall this suggests a complex psychophysiological aetiology underlying chronic pain conditions. The high proportion of variance in sexual pain explained by environmental factors further highlights the importance of specific environmental and contextual stressors in the development and maintenance of the condition.

Costs and benefits of laparoscopic cholecystectomy: abdominal wall lifting vs. pneumoperitoneum procedure.

BACKGROUND/AIMS: Gasless laparoscopic surgery using the abdominal wall lifting (AWL) method was first developed in Japan and has been used in various surgical fields. The AWL method allows the use of conventional reusable surgical instruments. The purpose of this study was to compare the cost-effectiveness of laparoscopic cholecystectomy (LSC) using the AWL method in relation to that using pneumoperitoneum (P) method. METHODOLOGY: Retrospective analysis of 431 LSC procedures between 1991 and 2004 was performed. The two surgical groups consisted of consecutively operated patients with a diagnosis of cholecystolithiasis or gallbladder polyps. One group consisted of 224 LSC procedures performed using the P method from 1992 to 1998 and the other group comprised 207 LSC performed using the AWL method from 1998 to 2004. All instruments used in the P method were disposable, whereas trocars, scissors, dissectors, graspers and L-hook electrodes (excluding clips) used in the AWL method were reusable. Hospital expenses, length of hospital admission and complication rates were analyzed. RESULTS: Mean hospital cost per case for LSC using the AWL method (dollars 6743) was 7% less expensive than that using the P method (dolars 7215). Costs of operative equipment contributed to the difference (mean dollars 912 per case) in total cost. Conversion to open cholecystectomy occurred in 6 cases (2.9%) using the AWL method and 7 cases (3.1%) using the P method. There were no significant differences in length of hospital admission or complication rates between the two groups. CONCLUSIONS: LSC using AWL method was less expensive than that using P method. This is mainly due to the use of reusable instruments in the AWL method. If LSC is performed using the AWL method instead of using disposable equipment, considerable savings can be achieved without compromising patient safety.

Mucins bearing the cancer-associated sialosyl-Tn antigen mediate inhibition of natural killer cell cytotoxicity.

The sialosyl-Tn (STn) antigen is a mucin-associated carbohydrate antigen expressed by a variety of adenocarcinomas. In the colon, expression of this antigen has been associated with a poor prognosis, independent of tumor stage or histology. The present study was performed to determine whether this adverse clinical outcome might be due to an interaction between STn-positive mucin and natural killer (NK) cell cytotoxicity. Ovine submaxillary mucin (OSM), a mucin highly rich in STn antigen, partially inhibited NK cell cytotoxicity against K562 target cells, but only at high concentrations. Low concentrations of OSM were not inhibitory but became markedly inhibitory in the presence of ammonium ions. Two other STn-positive submaxillary mucins also markedly inhibited NK cytotoxicity when combined with ammonium ions. Removal of sialic acid from OSM reversed the OSM/ammonium-mediated inhibition of NK cell activity. Unlike the submaxillary mucins, two mucins derived from human breast and lung cancer cells which lack the STn antigen, did not inhibit NK cell activity in this system. Likewise, four other non-mucin glycoproteins which lack STn expression did not inhibit NK cells despite having levels of sialic acid that were, in some cases, comparable to submaxillary mucin. These results indicate that mucins bearing the cancer-associated STn antigen can effectively inhibit NK cell cytotoxicity in the presence of ammonium ions. While this NK cell inhibition is likely to be caused by ammonium, mucin markedly enhances this effect, thereby implicating a novel immunomodulatory property of mucin.

Mucin gene expression in colonic tissues and cell lines.

Complementary DNA clones encoding four different mucin core peptides have been isolated. However, the expression of these mucin genes in the colon has not been systematically studied. The present investigation used Northern blot analysis to study the expression of MUC1, MUC2, MUC3, and MUC4 mRNA in paired normal and cancerous colonic tissues, and nine colon cancer cell lines. Results were correlated with the clinicopathological features of the tumors and with the immunohistochemical expression of several carbohydrate tumor-associated antigens that may reside on mucins. MUC1 mRNA was expressed in all colonic tissues, and levels in paired normal and cancer tissues were similar in most cases. MUC2 and MUC3 mRNAs were expressed in both normal and cancer tissues, but levels were often decreased in the cancers. MUC4 mRNA was present in normal mucosa with comparable or sometimes greater expression in cancers. There was no apparent correlation between the expression of any particular mucin gene or pattern of mucin genes and the site, stage, or histological type of tumor. In addition, the expression of mucin-associated carbohydrate antigens did not correlate with any individual mucin gene or group of mucin genes. In colon cancer cell lines all four MUC genes were expressed rather weakly or not at all. These results indicate that the human colon expresses a broad repertoire of mucin genes which are differentially regulated in malignancy. Whether this differential regulation of mucin genes affect the behavior of the tumor and results in the altered glycosylation commonly seen in these requires further investigation.

Glycoproteins as differentiation markers in human malignant melanoma and melanocytes.

Human malignant melanoma cell lines have been divided into three broad groups on the basis of morphology, pigmentation, tyrosinase levels, the 2-dimensional electrophoretic patterns of their [3H]glucosamine-labeled glycoproteins and the presence or absence of an extracellular matrix of fibronectin. The most pigmented cell lines were characterized by the synthesis of a novel glycoprotein with a molecular weight of 75,000 and the absence of a fibronectin matrix. As cultured skin melanocytes also had these characteristics, this group of melanomas appears to be the most differentiated. Melanoma cell lines in the amelanotic group were characterized by the synthesis of high levels of HLA-DR antigen and by the production of an extracellular fibronectin matrix.

Tumor-associated sialylated antigens are constitutively expressed in normal human colonic mucosa.

Immunohistochemical studies have indicated that sialylated carbohydrate antigens such as sialyl-Tn, sialyl-Le(a), and sialyl-Le(x) are expressed in a tumor-associated fashion in human colon. Since sialic acid residues are O-acetylated more extensively in normal colonic epithelium than in colon cancer cells, we examined whether deacetylation of colonic tissues might enable monoclonal antibodies to recognize these tumor-associated sialylated antigens. In normal colon, deacetylation turned most cases (82%) positive with anti-sialyl-Tn mAb TKH2; and in colon cancers, it increased the number of TKH2-positive cells. Sialyl-Le(a) and sialyl-Le(x) detection was also increased after deacetylation of normal and malignant colonic tissues so that the frequency of positive cases in normal tissues was similar to that in the cancers. However, in the stomach and pancreas, the same treatment rarely increased the detection of the sialylated epitopes in normal or cancerous tissues. Thus, the same sialylated epitopes can be expressed in a tumor-associated fashion by different mechanisms in different gastrointestinal organs; in the colon, these antigens are constitutively expressed and O-acetylated, whereas in the upper gastrointestinal tract, they are rarely O-acetylated, suggesting that other mechanisms such as differences in glycosylation account for the cancer-associated expression.

Immune sera and monoclonal antibodies define two configurations for the sialyl Tn tumor antigen.

Sialyl Tn (sTn) is a mucin-associated carbohydrate antigen expressed in most types of human adenocarcinoma. Defining the configuration of tumor cell surface sTn recognized by antibodies is important for understanding the basis for the cancer cell specificity of sTn-reactive mAbs, for the development of more effective mAbs, and for designing cancer vaccines against sTn. In this study, we compared the immunogenicity of synthetic single sTn disaccharide epitopes and clusters [sTn(C)] of 3 sTn epitopes covalently linked via serine to keyhole limpet hemocyanin [KLH; sTn-KLH and sTn(C)-KLH, respectively]. The cell surface sTn configurations were analyzed with the use of sera from mice immunized with these neoglycoproteins and a panel of sTn-reactive mAb. Sera from mice immunized with sTn-KLH reacted in direct and inhibition assays with sTn-human serum albumin (HSA) but only weakly with sTn(C)-HSA, whereas sera from mice immunized with sTn(C)-KLH reacted with sTn(C)-HSA but not with sTn-HSA. Both anti-sTn and anti-sTn(C) sera reacted with ovine submaxillary mucin (a natural source of sTn) and with sTn-positive human tumor cell line LS-C but not with sTn-negative LS-B cells. With regard to the sTn-reactive mAbs, B72.3 reacted exclusively with clustered sTn, whereas mAb B195.3R11 reacted preferentially with unclustered sTn. Results with mAbs TKH2, B239.1, and CC49 were less clear, although all reacted more strongly with clustered sTn than with unclustered sTn. These results suggest that sTn is recognized at the tumor cell surface in at least two quite distinct configurations, as clustered and nonclustered arrays.