Search

Symptomatic metastases in skeletal muscles are rare, and involvement of the masseter muscle is extremely rare, with only 3 reported cases. We report 2 additional cases of masseter-muscle metastases. Sonographically, the masseter-muscle metastases appeared as ill-defined, hypoechoic, heterogeneous lesions aligned with the long axis of the muscle. Fine-needle aspiration was confirmatory. The combination of sonography and fine-needle aspiration is the ideal method for diagnosing masseteric metastases., (Copyright 2000 John Wiley & Sons, Inc.)

Background and Purposes: Recent randomized studies from the West show that post-operative locoregional radiotherapy improves survival in lymph node (LN) positive pre-menopausal women with breast cancer but this benefit has not been established in the Chinese population. There is no published study on clinical outcomes (locoregional recurrence, survival and toxicities) of post-operative locoregional radiotherapy in Chinese women with breast cancer., Materials and Methods: We conducted a retrospective study of 399 female Chinese patients with breast cancer who had received post-mastectomy locoregional radiotherapy in our center between 1984 and 1990. The patients were stratified according to tumor size, menopausal and LN status. We analyzed the incidence and pattern of locoregional recurrence, distant recurrence, survival rates and toxicity related to radiotherapy., Results: Of the 399 patients 216 were pre-menopausal and 183 were post-menopausal. The mean age was 49.3 years (23-83). Distribution of tumor size and LN status of the two groups was similar. Median follow-up was 71.9 months. Locoregional recurrence occurred in 57 (14.3%) patients (pre-menopausal 24 (11.1%); post-menopausal 33 (18.3%) P=0.489). Recurrence was more common in LN positive patients (18.2%) than LN negative patients (9.2%). The pattern of locoregional recurrence was: chest wall 24, axilla LN 12, supraclavicular LN 10, chest plus LN 11. The distant recurrence rate was 39.6% for all patients and 75.4% for patients with locoregional recurrences. The overall 10-year survival rate for all patients was 54%. For LN positive patients the 10-year survival rate of pre-menopausal and post-menopausal women was 38 and 51%, respectively (P=0.207), and for LN negative patients the rate was 73 and 70%, respectively (P=0.603). Acute skin toxicity included redness (30.8%), dry desquamation (12.8%), and wet desquamation (6. 8%). Long-term toxicities included skin atrophy (0.3%), telangectasia (3.3%), pneumonitis (2.8%) and brachial plexus palsy (1.3%)., Conclusions: In our series Chinese patients with node-positive breast cancer have a relatively high locoregional recurrence rate in spite of mastectomy and post-operative radiotherapy. Limited use of adjuvant system chemotherapy may account, at least in part, for this finding. Clinical outcomes of post-operative radiotherapy in pre-menopausal and post-menopausal breast cancer patients are similar.

The promyelocytic leukemia (PML) gene, which encodes a transformation and growth suppressor, was first identified at the chromosomal translocation break point t(15;17) in acute promyelocytic leukemia (PML). To determine if the PML gene might be involved in other neoplasias such as lung cancer, PML expression was analyzed by immunohistochemical staining and in situ hybridization. Considerable PML protein expression in the PML-oncogenic domain (POD) structure was found in adenocarcinomas (ADC) and squamous cell carcinomas (SCC) of the lung, but was almost completely absent in all the small cell lung carcinomas (SCLC) examined. In situ hybridization showed that both mRNA and DNA of PML were present in SCLC and in normal lung, suggesting that the decreased protein expression was due to either a defect in translation or protein instability, rather than the consequence of decreased transcription or gene deletion. Double staining showed that PML expression was inversely correlated with the proliferation marker Ki-67 and positively correlated with levels of apoptotic cells in these tumors. To determine if the precursor cells of SCLC, the neuroendocrine-producing cells, express PML, double labeling was performed with PML and chromogranin A, a bio-marker for neuroendocrine cells. Neuroendocrine cells from normal tissues were found to be PML positive, indicating that the lack of PML protein in SCLC is associated with the tumorigenic phenotype and is not the result of cell-lineage specificity. Thus, the decreased PML expression may play an important role in SCLC development., (Copyright 2000 Wiley-Liss, Inc.)

Objective: Hemorrhagic cystitis is a well-known complication of cyclophosphamide therapy but extensive involvement of the entire urinary tract is far less common. We report here a patient who developed severe hemorrhagic pyelitis, ureteritis, and cystitis after one cycle of cyclophosphamide-containing combination chemotherapy., Method: A patient with synchronous carcinoma of the ovary and the uterus developed severe hemorrhagic pyelitis, ureteritis, and cystitis leading to bilateral hydronephroses and acute renal failure after one cycle of combination chemotherapy containing cyclophosphamide. The blood clots in the upper urinary tract were aspirated endoscopically and bilateral internal ureteric stents were inserted., Result: She underwent a prolonged diuretic phase with several episodes of hypokalemia, hypomagnesemia, and hypocalcemia and required intensive fluid and electrolytes replacement. Subsequently, she recovered fully with the ureteric stents removed 26 days later., Conclusion: In contrast to previous reports, where 2.8 g of cyclophosphamide was estimated to be the minimum cumulative dose required to cause hemorrhagic cystitis, this case illustrates that severe hemorrhagic complication can occur even after a low dose of cyclophosphamide (600 mg/m(2), total dose of 846 mg). Prompt diagnosis and intervention may be life-saving., (Copyright 2000 Academic Press.)

Nasopharyngeal carcinoma (NPC) is a commonly occurring tumor in southern China. Although several causative factors have now been recognized, the genetic basis underlying its tumorigenesis is still unclear. To identify potential chromosomal aberrations for further investigations, comparative genomic hybridization (CGH) analysis was applied to the study of genomic imbalances in 10 NPC biopsy specimens. Before CGH analysis, the tumor cell content within the biopsy specimens was enriched by tissue microdissection, and universal genome amplification was performed on the recovered DNA. Recurrent chromosomal gains were detected on 1q (6 of 10 cases), 2q (5 of 10 cases), 3q (7 of 10 cases), 6p (8 of 10 cases), 6q (5 of 10 cases), 7q11.2 (4 of 10 cases), 8q (6 of 10 cases), 11q13, 12, and 15q (8 of 10 cases each), 17q (6 of 10 cases), and 20q (5 of 10 cases). Common losses were identified on 3p (5 of 10 cases), 9p (5 of 10 cases), 11q14-qter (8 of 10 cases), and 14q (5 of 10 cases). Among these aberrations, 7, 8, and 11 gains were further investigated on a series of NPC tissue samples, by interphase fluorescent in situ hybridization (FISH), for the incidence of alpha-satellites: 7, 8, and 11 c-myc and Int-2. Low-level increases of alpha-satellite 7 (9 of 34 cases; 26.5%), alpha-satellite 8 (15 of 34 cases; 44%), and alpha-satellite 11 (8 of 32 cases; 25%) were detected, whereas high-level copy gains of c-myc (21 of 34 cases; 62%) and Int-2 (26 of 34 cases; 76.5%) were more frequently found. Our series is the first to identify genomic overrepresentations of c-myc and Int-2 in NPC. The high incidence of Int-2 amplifications strongly suggests a role of this proto-oncogene in the pathogenesis of NPC.

Anti-extractable nuclear antigen (ENA) antibodies were assayed by counter immunoelectrophoresis (CIE) and immunoblotting in patients with systemic lupus erythematosus (SLE). We found the two methods showed good concordance rates, the lowest being 67% for anti-SS-A. Immunoblotting was more sensitive in detecting anti-Sm, anti-SS-B and anti-PCNA (proliferating cell nuclear antigen); CIE was more sensitive for anti-nRNP and anti-SS-A. Overall, the prevalence of these anti-ENA antibodies in SLE was increased by 9-20% if immunoblotting was used in addition to CIE. Sera specific for the 52 kDa peptide of the SS-A antigen (anti-52kDa SS-A) were better detected by immunoblotting. Anti-PCNA antibody was found in 6.3% of SLE patients and was associated with active disease and hemolytic anemia. The positive rate of anti-Sm was 9% by CIE and 23.7% by immunoblotting and this antibody was a specific marker for SLE using either method. It was concluded that using immunoblotting in addition to CIE, the overall sensitivity of detection of anti-ENA antibodies in SLE was increased and clinically useful antibodies such as anti-52kDa SS-A and anti-PCNA could be detected.

Hepatitis B virus (HBV) reactivation has been described in cancer patients who received cytotoxic/immunosuppressive therapy and may result in liver damage of varying degrees of severity. There is no known effective treatment. Lamivudine, a nucleoside analogue, has been found to suppress HBV replication and to improve histology in chronic carriers of hepatitis B virus. The outcome of lamivudine therapy (at doses of 100 or 150 mg/day) in eight patients who developed HBV reactivation while receiving cytotoxic chemotherapy is described. Each of the eight patients had >98% suppression of the pretreatment HBV DNA levels. Three of the five patients who were initially HBeAg positive underwent seroconversion. Five patients had normalization of liver function tests and improvement in clinical condition. However, one patient died of hepatic failure due to HBV-related submassive liver necrosis, and two died of widespread metastases (including liver) from the primary malignancies. It is concluded that early commencement, i.e., at the onset of HBV reactivation before severe hepatic decompensation, of lamivudine may be effective in the control of HBV reactivation during chemotherapy. In Hong Kong, where hepatitis B infection is endemic, we propose to screen all cancer patients for hepatitis B surface antigen before immunosuppressive/cytotoxic therapy, and to closely monitor liver function of those who are found to be HBsAg seropositive.

The purpose of this Phase II study was to determine the response rate, the toxicity, and the effect on survival of the combination of cisplatin, doxorubicin, 5-fluorouracil, and alpha-IFN (PIAF) in advanced unresectable hepatocellular carcinoma. Fifty patients with either unresectable or metastatic disease were treated with PIAF: cisplatin (20 mg/m2 i.v., days 1-4), doxorubicin (40 mg/m2 i.v., day 1), 5-fluorouracil (400 mg/m2 i.v., days 1-4), and alpha-IFN (5 MU/m2 s.c., days 1-4). Treatment was repeated every 3 weeks to a maximum of six cycles. All patients were evaluable for response, toxicity, and survival. As assessed by conventional imaging criteria, there were no complete responses, but 13 patients (26%) had a partial response. Among the 36 patients who had an initially high alpha-fetoprotein level (>500 ng/ml), 15 (42%) had a >50% fall after therapy. Nine patients underwent surgical resection after achieving partial response and, in 4 of these patients, histological examination of the resected specimens revealed no viable tumor cells. All these nine patients are alive, and eight patients remain in complete remission at between 7.6 and 25.8 months at the time of analysis. The overall median survival was 8.9 months. Toxicity was mainly myelosuppression and mucositis. There were two treatment-related deaths due to neutropenic sepsis. PIAF is active in hepatocellular carcinoma despite considerable hematological toxicity. Complete pathological remission is possible with this systemic combination. Apparently, persistent radiological lesions may still represent complete pathological resolution of active disease.

The majority of research on romantic relationships has tended to focus on marriage, with relatively less attention paid to dating. This study examined the relationship between Asian American dating, both interracial and intraracial, and a variety of factors thought to be associated with dating in this population, including acculturation, ethnic identity, attractiveness, interracial dating experience, ethnicity of friends, parental influence over dating, and density. Participants were administered measures of these variables and were asked questions regarding their likelihood of dating both Asian Americans and White Americans. An interesting pattern of results emerged when the variables were put into regression equations to predict both interracial and intraracial dating. Findings are presented and implications discussed.

Background: Resection of hepatocellular carcinoma is potentially curative, but local recurrence is common. In this prospective randomised trial, we aimed to find out if one dose of postoperative adjuvant intra-arterial iodine-131-labelled lipiodol could reduce the rate of local recurrence and increase disease-free and overall survival., Methods: Patients who underwent curative resection for hepatocellular carcinoma and recovered within 6 weeks were randomly assigned one 1850 MBq dose of 131I-lipiodol or no further treatment (controls). We compared rates of recurrence and disease-free and overall survival (the primary endpoints) between the two groups by intention to treat. We planned an interim analysis when 30 patients (both groups together) had been followed up for a median of 2 years, with the intention of stopping early if the between-group difference in disease-free survival was significant (p=0.029)., Findings: Between April, 1992, and August, 1997, we recruited 43 patients: 21 received intra-arterial 131I-lipiodol and 22 received no adjuvant treatment. During a median follow-up of 34.6 (range 14.1-69.7) months, there were six (28.5%) recurrences among the 21 patients in the adjuvant treatment, compared with 13 (59%) in the controls (p=0.04). Median disease-free survival in the treatment and control groups was 57.2 (0.4-69.7) and 13.6 (2.1-68.3) months, respectively (p=0.037). 3-year overall survival in the treatment and control groups was 86.4% and 46.3%, respectively (p=0.039). The interim analysis showed a significant increase in disease-free survival in the treatment group compared with the controls (p=0.01), so we closed the trial early. 131I-lipiodol had no significant toxic effects., Interpretation: In patients with hepatocellular carcinoma, one 1850 MBq dose of intra-arterial 131I-lipiodol given after curative resection significantly decreases the rate of recurrence and increases disease-free and overall survival.

Purpose: A multi-centre randomized phase II study of single agent nolatrexed dihydrochloride versus doxorubicin was undertaken in Chinese patients with advanced hepatocellular carcinoma (HCC) to study and compare the clinical efficacy of the two drugs., Methods: Fifty-four patients with clinical or histological diagnosis of HCC were randomized in a 2:1 ratio to receive nolatrexed or doxorubicin. Nolatrexed 725 mg/m(2)/day was given by continuous infusion via a central venous device for 5 days and doxorubicin 60 mg/m(2) was given as a rapid intravenous infusion every 3 weeks., Results: No objective responses were observed in either treatment arm. Two patients in the nolatrexed arm and none in the doxorubicin arm had >50% decline in serum alpha-fetoprotein. The median survival for the patients in the nolatrexed and doxorubicin arms was 139 days and 104 days, respectively. Moderate toxicities including leukopenia, thrombocytopenia, mucositis and skin rash were observed in both treatment arms., Conclusion: Nolatrexed and doxorubicin are minimally active in the treatment of advanced HCC. Given the small sample size, no difference is observed between the two drugs.

The aim of this study was to determine the efficacy and toxicity of combination paclitaxel and carboplatin chemotherapy in patients with metastatic and/or locoregionally advanced nasopharyngeal carcinoma (NPC). Patients with metastatic and/or locoregionally advanced NPC were treated with carboplatin calculated according to an AUC of 6 mg ml/min (based on Calvert formula) given as an intravenous (i.v.) bolus, followed by paclitaxel 135 mg/ml2 given as an i.v. infusion over 3 h with standard premedication. Cycles were given 3 weekly to a maximum of six. From January 1996 to November 1997, 27 patients were entered and assessable for response and toxicity. A total of 122 cycles were given and the median number of cycles given was five. The overall response rate was 59% (16/27). There were 3 (11%) complete responses, 13 (48%) partial responses, 5 (19%) static disease and 6 (22%) progressive disease. Toxicity was mainly haematological including: grade 3/4 neutropenia (39 cycles, 32%), grade 3/4 anaemia (nine cycles, 7%), grade 3/4 thrombocytopenia (eight cycles, 7%). There were three episodes of neutropenic fever (3%). Non-haematological toxicities were mild and infrequent. Paclitaxel and carboplatin combination chemotherapy is active in NPC and has tolerable toxicity. Further study with dose escalation is required to assess its optimal efficacy.

Background: Lymphoepithelioma-like carcinoma (LELC) of the lung occurs at a higher frequency in Asian compared with Western patients. Its association with Epstein-Barr virus varies among different ethnic groups., Methods: Nine patients with primary LELC of the lung treated at a single institution with a multimodality approach comprised of surgery, chemotherapy, and radiotherapy are reported. Chemotherapy was comprised of cisplatin, 100 mg/m2, on Day 1 and 5-fluorouracil, 1 g/m2, on Days 2, 3, and 4., Results: Five male and 4 female patients were treated over a 3-year period. Eight patients were non-smokers. Three patients had operable disease. Two of these patients received adjuvant radiotherapy or chemotherapy and remained free of recurrence at 18 and 20 months, respectively; 1 patient received no adjuvant treatment, and palliative chemotherapy was given for subsequent recurrent disease. Six patients had inoperable disease and received palliative chemotherapy +/- radiotherapy. Five patients had distant metastatic disease at presentation. Of the 7 patients who were evaluable for response to chemotherapy, 71.4% had a partial response and 28.6% had progressive disease. One patient who was evaluable for response to radiotherapy achieved a partial response., Conclusions: Primary LELC of the lung has a high rate of systemic metastasis and is highly chemosensitive. A multimodality approach to the management of this disease is recommended.

Background: Chemotherapy containing anthracycline is the standard initial treatment for aggressive non-Hodgkin's lymphoma (NHL), and the International Prognostic Index (IPI) is widely accepted as the standard tool for determining the prognosis of patients with this disease. However, the data on which the IPI was based primarily came from studies conducted in Western countries. It may not be directly applicable to Asian populations, in which the incidence of primary extranodal lymphoma (PENL) is known to be high., Methods: The authors conducted a retrospective study of 218 patients with aggressive NHL who were treated with chemotherapy. They analyzed the distribution of stage and pathology, prognostic factors, toxicity, and treatment outcome. The IPI was then applied and its ability to identify distinct prognostic groups tested., Results: Eighty-six patients (39.4%) had lymph node lymphoma (LNL) and 132 (60.6%) had primary extranodal lymphoma (defined as non-Hodgkin's lymphoma with primary presentation, bulk of disease, and histologic confirmation at an extranodal site). The most common primary extranodal sites were the stomach (22%) and Waldeyer's tonsillar ring (18.9%). The complete response rate of PENL patients to chemotherapy containing anthracycline was 52%, as compared with 64% of the LNL group. The 5-year survival rates for patients with LNL and PENL were 57.4% and 52.1%, respectively. The toxicity in the two patient groups was similar. Four of the prognostic factors in the IPI-age, serum LDH, performance status, and disease stage-predicted significantly different survival for PENL and LNL patients. However, the number of extranodal sites involved was not a significant predictive variable in PENL., Conclusions: The IPI was applicable to this Chinese population in which the incidence of PENL was high, although the number of extranodal sites did not achieve statistical significance as a risk factor. A proposal for modification was made. Chemotherapy containing anthracycline was an effective treatment for both PENL and LNL patients.

Purpose: A single-institution phase II trial of Temodal (temozolomide, SCH52365) in Chinese patients with advance nasopharyngeal carcinoma was undertaken to determine the efficacy and safety of the drug in this population., Methods: A total of 14 patients with metastatic or locoregionally recurrent nasopharyngeal carcinoma were entered into the study. One patient was unevaluable. Temodal was given at doses of 150 or 200 mg/m2 daily on days 1-5 every 28 days., Results: In all, 30 cycles of Temodal were given with no significant toxicity. All 13 (100%) evaluable patients had progressive disease after 2 (84.6%) or 4 (15.4%) courses., Conclusion: Temodal given on this schedule has no activity in advanced nasopharyngeal carcinoma.

This article attempts to address standards of physical attractiveness in the United States and the effects these standards have on Asian Americans. In the U.S., attractiveness appears to be defined overwhelmingly by White criteria, and people of color are often neglected or overlooked. There appears to be convergence from a number of fields (i.e., ethnic studies, film studies, and literature, in addition to experts in the field of ethnic minority mental health) that White standards of attractiveness exert a deleterious effect on Asian Americans. This article will discuss the limited mental health research that does exist in this area and make suggestions for further research in this field. Discussion will center around acculturation and ethnic identity as possible mediating factors that may influence reactions to standards of attractiveness.

Mass media sources such as television and movies arguably offer up little in the way of positive Asian/Asian American images or role models. This article contends that the media do not often portray the diversity that is inherent within the Asian American culture and that such a paucity of Asian images may greatly affect perceptions Asian Americans may hold both of their own racial group and of the larger society. This article examines both media images of Asians and Asian Americans and autobiographical information from Asian American literature to illustrate the potentially detrimental effects of being a person of color in a society that emphasizes a monoracial standard of beauty. Information gleaned from first-hand accounts from Asian Americans often points to the media as a potent source of information as to how attractiveness is defined and measured. This article concludes with a discussion of some brief case examples and ethical imperatives for mental health workers in terms of both self-awareness and education as well as considerations for culturally sensitive therapy.

We report here a case of fatal Penicillium citrinum infection. The patient, who suffered from acute myeloid leukemia, developed signs and symptoms typical of fungal pneumonia and pericardial tamponade after undergoing standard induction chemotherapy. Despite attaining complete remission of her leukemia, the patient succumbed 8 weeks after presentation. At autopsy, multiple nodular cavitary pulmonary lesions with invasion by fungal hyphae were found. Pericardial and lung tissue obtained at autopsy grew P. citrinum, a fungus ubiquitous in the environment but seldom reported as a pathogen. The microbiological findings were consistent with the histopathological features and confirmed this as a case of true P. citrinum infection causing fatal pulmonary and pericardial complications in an immunocompromised host.

The enzyme disaggregatase (Dag) from Methanosarcina mazei was studied immunochemically. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified Dag under reducing and nonreducing conditions revealed a single band with a 94-kDa molecular mass. Dag was found to be immunogenic in rabbits; a polyclonal antibody probe was prepared and used to detect the enzyme by slide immunoenzymatic assay, immunofluorescence, and immunoblotting in various species of Methanosarcina known to convert from packets to single cells, including M. mazei. The enzyme could not be detected in other members of the family Methanosarcinaceae that do not convert. By immunogold electron microscopy, Dag was mapped to the cell wall of packets and to the cell membrane of single cells of two M. mazei strains.

Annexins are structurally related proteins that bind phospholipids in a Ca2(+)-dependent manner and possess at least four conserved 70-amino acid repeat domains. The ability of certain annexins to promote contact between vesicle membranes in vitro has prompted the suggestion that these proteins regulate membrane traffic in exocytosis. We have previously found that annexins I and II promote contact between vesicles whereas annexin V does not. In order to understand the mechanism of annexin I-mediated vesicle-vesicle contact, we prepared a monoclonal antibody that specifically inhibits annexin I-mediated vesicle aggregation. We identified the domain of annexin I recognized by this monoclonal antibody by using it to screen an expression library containing random fragments of annexin I cDNA. The antibody identified a fragment encoding amino acids 41-118 (the first repeat plus 8 residues of the amino-terminal tail). We constructed a chimeric protein containing these amino acids of annexin I fused to the second, third, and fourth repeats of annexin V. Transfer of this domain conferred the ability to promote vesicle aggregation, confirming that this domain participates directly in mediating contact between vesicle membranes.

Two separate experiments were conducted using modifications of protein A-gold immunoelectron microscopy (PAGIEM) to evaluate the ability of sera from calves vaccinated against Haemophilus somnus to bind virulent organisms (experiment I) and to detect differences in the antibody accessible antigenic sites on the outer membrane of selected strains of H. somnus having different virulence attributes using a high IgG2 titre specific bovine hyperimmune serum (experiment II). The results of experiment I demonstrated that the direct opsonisation of H. somnus by specific antisera was related to its IgG2 titre. In experiment II, strain-dependent differences in the labelling of antigenic sites by specific IgG2 antibodies were observed. The virulent strains of both septicaemic and genital isolates of H. somnus showed higher protein A-gold labelling than their non-virulent counterparts. The results from a comparison of pathogenic and non-pathogenic respiratory isolates did not reveal the same difference in labelling intensity. The studies demonstrated the PAGIEM technique to be a sensitive, versatile and a reliable laboratory method to analyse antigen-antibody interactions of H. somnus.

Two subpopulations, layer 2 (density 1.025-1.029 g/ml) and layer 3 (density 1.032-1.043 g/ml) of low density lipoproteins (LDL) were isolated from fresh human plasma of normal lipidaemic subjects by density gradient ultracentrifugation. Chemical analyses demonstrated the ratios of triglyceride/cholesterol ester decreased with increasing densities of subfractions. These subfractions together with triglyceride-rich lipoproteins (layer 1, density less than 1.019 g/ml) were subjected to physicochemical studies by differential scanning calorimetry (d.s.c.) and nuclear magnetic resonance (n.m.r.) spectroscopy. The average transition temperature (Tt) of layer 2 was 34.20 +/- 0.83 degrees C and that of layer 3 was 37.25 +/- 0.35 degrees C. In addition, many of the layer 3, but not layer 2 and layer 1, samples showed structural alteration and gave rise to an average Tt of 39.18 +/- 1.24 degrees C. The structural alteration could be detected with polarizing light microscopy showing birefringent spherulites at body temperature. The peak Tt values obtained by d.s.c. were in good agreement with those by n.m.r. spectroscopy. These results demonstrate the physicochemical heterogeneity within the LDL density region and suggest that layer 3 subpopulation is much more labile than the others.

Pigs with two mutant epitopes, Lpb5 of apolipoprotein B (apoB) and Lpu1 of a yet undefined apolipoprotein, specified by a haplotype Lpb5-Lpu1 and fed a cholesterol-free low fat diet show hypercholesterolemia. The purpose of this study was to establish whether a direct relationship exists between the swine lipoprotein concentration/composition and the genotype for the Lpb5-Lpu1 haplotype; i.e., homozygote versus heterozygote. Lipoproteins of fasted plasma from hypercholesterolemic swine, homozygous (HmHC) and heterozygous (HtHC) for Lpb5-Lpu1, and from normolipidemic (NL) pigs of other Lpb-Lpu haplotypes were separated into five layers by density gradient ultracentrifugation. Layer 1 contained particles of d less than 1.019 g/ml and layer 5 particles of d greater than 1.073 g/ml. Layers 2, 3, and 4 represented subfractions of low density lipoproteins (LDL). The plasma total cholesterol (TC) of the HmHC group (300 +/- 84 mg/dl) was different (P less than 0.05) from the HtHC group (200 +/- 80 mg/dl) and in both HmHC and HtHC, TC was significantly higher (P less than 0.0005 and P less than 0.005, respectively) than that of the NL group (69 +/- 14 mg/dl). The elevation in plasma TC was due to the increased TC in layers 2 and 3: a 13- and 7-fold increase in HmHC and a 7- and 4-fold increase in HtHC in layers 2 and 3, respectively. Parallel increases in unesterified cholesterol were observed in these two layers. Marked increases in apoB were also observed in layers 2 and 3 of HmHC and intermediate increases in apoB in the same two layers of HtHC.(ABSTRACT TRUNCATED AT 250 WORDS)

Although the discovery of stop codon has explained the mechanism for the formation of the intestinal marker, apolipoprotein B-48, the dispute regarding the presence of apolipoprotein B-100 in the intestine is still unsettled. To further investigate the characteristics of intestinal apolipoprotein B, the newly developed human colonic adenocarcinoma Caco-2 cells which express functional properties of the differentiated enterocytes, were used. SDS-polyacrylamide gel electrophoresis analyses of the intact culture medium or its lipoproteins of d less than 1.23 g/ml showed the presence of only a single protein band of apolipoprotein B-100 with no detectable apolipoprotein B-48. After immunoblotting with oligoclonal antibodies to the amino-terminal peptide of apolipoprotein B, a trace amount of apolipoprotein B-48 was observed in the isolated lipoproteins, but not in the intact culture medium. These results suggest that apolipoprotein B-100 is the major form of apolipoprotein B secreted by human intestinal cells.

Human hepatocarcinoma Hep G2 cells were grown in culture medium containing [45Ca2+]. The secreted lipoproteins of d less than 1.063 g/ml and d 1.063-1.21 g/ml were isolated from the culture media and analyzed by 3.3% and 7% SDS-polyacrylamide gel electrophoresis. Radioactivity profiles of [45Ca] from the gels showed that the peak of radioactivity corresponded to the apolipoprotein B band. The molar ratio of the incorporated [45Ca2+] and apolipoprotein B was close to unity. No radioactivity was found associated with any other secreted apolipoproteins. To confirm these findings, apolipoprotein B-containing lipoproteins were precipitated with anti-apolipoprotein B and high density lipoproteins were precipitated with anti-apolipoprotein A-I. Only the former precipitate was radioactive. These results suggest that apolipoprotein B is a calcium binding protein.

Water-soluble apolipoprotein B was prepared from fresh plasma by quick isolation of low density lipoproteins and immediate delipidization under non-oxidative conditions. The denatured protein in 6 M guanidine X HCl was reduced and carboxymethylated, dialyzed through 6 M urea/preservatives and to 1% ammonium acetate/0.05% EDTA/0.13% epsilon-amino caproic acid, pH 7.3 under N2 at 4 degrees C. The morphological studies were carried out by electron microscopy with negative staining and freeze fracture. Both these techniques showed that apolipoprotein B is a globular protein with average diameter of 11.48 +/- 1.25 nm (n = 978). The M.W. of apolipoprotein B calculated from this particle size was comparable to that from amino acid sequence.

Molecular forms of apolipoprotein B (ApoB) were studied in the rat intestinal chyle by SDS-polyacrylamide gel electrophoresis, immunoblotting and immunodiffusion. Time studies on intestinal chyle showed the presence of B-100 in all the samples analyzed within 3 hr after drawing. However, the analyses repeated on day 2 or day 3 revealed disappearance of B-100 and appearance of B-48. Addition of 3 mM EDTA, 10 mM diisopropylfluorophosphate, 5 mM chloroquine and 10 mM epsilon-amino caproic acid slowed down but could not prevent the disappearance of B-100. Chylomicrons isolated from chyle in the presence of preservatives immediately after drawing displayed B-100 as a major and B-48 as a minor ApoB form. However, repeatedly washed chylomicrons or those isolated from chyle 18-24 hr after drawing showed B-48 as the only ApoB present. These results suggest that rat intestine synthesizes B-100 which is quickly converted to smaller molecular form.