Synovial membrane cytokine profiles in reactive arthritis secondary to intravesical bacillus Calmette-Guérin therapy

We describe the cellular infiltrate and cytokine profile in sequential synovial membrane biopsies from a patient with acute followed by chronic synovitis after intravesical bacillus Calmette-Guérin (BCG) therapy for an in situ transitional cell carcinoma of the bladder. Histological and immunohistochemical analysis of 3 synovial biopsies were done sequentially over a 9 month period. The patient was HLA-B27 positive, but HLA-DR4 negative, and did not have the "shared epitope." Unlike other cases, this patient's arthritis did not respond initially to nonsteroidal antiinflammatory drugs and was exacerbated by corticosteroid therapy. The synovitis took a neutrophilic form, with marked synovial membrane content of interleukin 8 (IL-8) and tumor necrosis factor alpha (TNF-alpha). It subsequently developed into chronic lymphoplasmacytoid synovitis, similar to rheumatoid arthritis (RA), with decreased IL-8 but continuing IL-1 and TNF-alpha production in the synovial membrane. The synovitis resolved to a fibrotic synovium with residual thickening of the synovial lining layer and continued production of TNF-alpha. Thus, during the evolution of this arthritis, the synovial layer and continued production of TNF-alpha. Thus, during the evolution of this arthritis, the synovial membrane yielded a cellular infiltrate and cytokine content that had marked similarities with that seen in RA; however, the arthritis eventually remitted spontaneously.

Effects of family structure information on nurses' impression formation and verbal responses

The purpose of this study was to investigate the effects of family structure information on how nurses (a) interpreted information, (b) gathered data, and (c) responded to a patient. Nurses were randomly assigned to see one of eight videotaped interviews portraying: married mother, married with no children, divorced mother, divorced with no children, unmarried mother, unmarried with no children, remarried with spouse's children (stepmother), and remarried with no children. The results indicate that the technical aspects of nursing may be affected only in a relatively minor way, but the affective dimensions of nursing care may be more detrimentally influenced by knowing about a patient's family structure.

Single and double autotransplants for relapsing/refractory Hodgkin's disease: results of two consecutive trials

To evaluate a strategy of one cycle of dose-intensive chemotherapy for patients with Hodgkin's disease in sensitive relapse and two cycles for those with refractory disease, 122 patients received dose-intensive chemotherapy followed by autotransplant in two consecutive studies. Patients with refractory disease were offered a second transplant with different conditioning in the absence of progression or excessive toxicity. CR was present after treatment in 46% while 16% died in the peritransplant period. Of 41 patients with primary refractory disease and 42 with refractory relapse, 24 and 21 respectively received a second cycle. Of these 45 refractory patients, 12 were in CR and 11 in PR after the first cycle and 10 of these 11 in PR achieved a durable CR with the second transplant. The CR rate is 37% in patients with refractory relapse and 19% in those with primary refractory disease. At a median follow-up of 4 years, median survival is 45 months. Progression-free survival of the refractory patients who could receive a second cycle was similar to that of patients with sensitive disease. A sequential transplant strategy is feasible. A subgroup of patients with refractory disease can achieve long-term survival after sequential BMT.

Correlates of child care providers' interpretation of pediatric AIDS: implications for education and training

A total of 212 child care providers residing in a southeastern state were surveyed about their knowledge and attitudes toward AIDS and child care policies. Providers' feeling about caring for an HIV-infected child, rather than their perceived knowledge of AIDS, were most consistently correlated with their factual knowledge and positive attitudes toward AIDS. These results suggest that providers may pay more attention to AIDS information and become more accepting of recommended child care policies when they are able to personalize AIDS within the context of their work with young children. Implications for education are discussed within the context of the Health Belief Model.

A nonradioactive method of in situ hybridization that uses riboprobes and paraffin-embedded tissue and its combination with immunohistochemistry

Current research into cytokine production in tissue sections relies on the detection of cytokine proteins using a variety of immunohistochemical methods. The disadvantages of this technique are that precise localization to a particular cell is difficult and it is uncertain whether the cells detected by this method are the origin or target of the cytokine or rather have nonspecifically absorbed the secreted cytokine. This question can be clarified using in situ hybridization, but current techniques are insensitive, poorly localizing, or time consuming. Biotin-labeled riboprobes were generated from cDNA fragments sandwiched between two RNA polymerase promoters (SP6 and T7 RNA polymerases) using a commercial riboprobe generation kit containing biotin-labeled UTP. The in situ hybridization technique was used to demonstrate cytokine mRNA in a range of tissues containing an inflammatory infiltrate and with a range of cytokine probes. This technique of in situ hybridization was combined with immunohistochemistry using an immunoalkaline phosphatase technique to show the powerful combination of these two techniques. The biotin-labeled riboprobes were sensitive enough to detect a range of cytokine mRNAs in a variety of tissue sections. The technique can be completed over a 24-h period and produces a stable color product that can be stored for long periods and can be quantitated using image analysis techniques. This technique was performed on paraffin-embedded tissue as well as cryosections and allowed for the detection of mRNA in archival tissue. It was also successfully combined with immunohistochemical techniques to determine simultaneously the localization of a cytokine product in particular cell lineages. A nonradioactive method for in situ hybridization using biotin-labeled riboprobes is described; it is capable of detecting mRNA products from a range of genes in a variety of tissue samples. An amplification step in the method enhances the sensitivity to a level that approaches that of radioactive methods, while maintaining the speed, safety, and simplicity of an immunoperoxidase detection system. The ability to use paraffin-embedded tissue with this method allows for improved tissue architecture and examination of archival tissue. These features should ensure greater use of in situ hybridization techniques in future research studies.

Synovial membrane inflammation and cytokine production in patients with early osteoarthritis

OBJECTIVE

To establish the presence of inflammation in and cytokine production by synovial membranes from patients with various stages of early osteoarthritis (OA), with knee pain, normal knee radiographs, and arthroscopic evidence of chondral damage.

METHODS

Synovial membrane samples were obtained from the knees of 63 patients at the time of arthroscopy for unexplained knee pain or at the time of joint replacement surgery. Evaluations of synovial membrane variables including thickness of lining layer, vascularity, and inflammatory cell infiltrate were by a blinded observer. In a subset of 20 patients, production of interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), and IL-1 receptor antagonist (IL-1ra) at the mRNA and protein levels was determined using in situ hybridization with biotin labeled ribo-probes and immunohistochemistry.

RESULTS

There was evidence of thickening of the lining layer, increased vascularity, and inflammatory cell infiltration in synovial membranes from patients with all grades of OA, with the most marked changes seen in synovial tissue from patients with advanced grades of OA. Similarly, production of IL-1 alpha, IL-1 beta, and TNF-alpha was present in synovial membranes from all patients with OA, irrespective of the degree of articular cartilage damage. There was a trend to decreased levels of IL-1ra in synovial membranes from patients with OA that did not attain statistical significance. Similarly, there was a decrease in the ratio of IL-1ra to IL-1 alpha and beta with increasing grades of OA.

CONCLUSION

Chronic inflammatory changes with production of proinflammatory cytokines are a feature of synovial membranes from patients with early OA, with the most severe changes seen in patients at the time of joint replacement surgery resembling those seen in rheumatoid arthritis. This low grade synovitis results in the production of cytokines that may contribute to the pathogenesis of OA.

CODBLAM IV chemotherapy for large cell lymphoma: sequential use of infusional vincristine and bleomycin and "high dose" consolidation

BACKGROUND

Based on prior results in large cell lymphoma (LCL) with COPBLAM (Cyclophosphamide, Oncovin, Prednisone, Bleomycin, Adriamycin, Matulane) I and COPBLAM III, CODBLAM (Cyclophosphamide, Oncovin, Dexamethasone, Bleomycin, Adriamycin, Matulane) IV was developed to intensify treatment further by utilizing four sequential cycles of infusional chemotherapy followed by high-dose chemotherapy and cycle active agents.

METHODS

Sixty-one patients with LCL, mostly B-cell lymphoma, with 54% >60 years of age, were treated with daily continuous infusion of vincristine 1.0 mg/m2 days 1-2, bleomycin 4 mg/m2 i.v. push x 1 only followed by daily infusion 4 mg/m2 days 1-5, dexamethasone 10 mg/m2 days 1-5, procarbazine 100 mg/m2 orally days 1-5, doxorubicin 35 mg/m2 i.v. push day 1 (escalated), and cyclophosphamide 350 mg/m2 i.v. push day 1 (escalated), all given every 3 weeks for four cycles. After infusions, patients were restaged and treated with single courses of doxorubicin 90 mg/ m2 i.v. push followed at 3 weeks with cyclophosphamide 1500 mg/m2 i.v. push (both with concomitant vincristine 1 mg/m2 i.v. push and dexamethasone 10 mg/m2 p.o. daily for 5 days). Remaining treatment consisted of methotrexate 120 mg/m2 i.v. push with citrovorum rescue, cytarabine 250 mg/m2 i.v. push, and etoposide 100 mg/m2 i.v. infusion over 1 h, all given every 10 days for six cycles.

RESULTS

The overall complete response (CR) rate was 88%. Of all patients, 36 (59%) are sustained disease free at a median follow-up time of 55 months. In patients age < or = 60 years, 89% achieved CR and 85% of patients age >60 years attained CR. CR was achieved in 83% of patients with constitutional B-type symptoms, 69% of patients with bulky adenopathy, and 86% of patients with immunoblastic histology. Toxicity was primarily pulmonary, occuring in 15% of patients. One toxic death was observed.

CONCLUSIONS

Infusional CODBLAM IV may represent an effective and unique treatment for LCL.

Ki-1 skin lymphoproliferative disorders: management with radiation therapy

Lymphomatoid papulosis and anaplastic large Ki-1 lymphoma of skin share unique clinical and pathological features. Appropriate therapy for multiple Ki-1 lymphoproliferative lesions without systemic involvement remains controversial. This paper presents results achieved with local radiation therapy. Two patients with multiple Ki-1 skin lymphoproliferative tumors were treated with local radiation using various techniques determined by the size and the depth of tumor invasion. Most lesions received 3000 cGy in 3 weeks. Complete response was achieved in all treated areas. There was virtually no morbidity. After more than 3 years, none of the treated areas developed local recurrence, and there was no evidence of internal dissemination. Ki-1 skin lymphoproliferative disorders are highly radiosensitive. When the disease is confined to the skin, and there is no evidence of spontaneous regression, or if palliation of symptoms is necessary, local radiation therapy may be an effective modality.

Effects of pulse methylprednisolone on cell adhesion molecules in the synovial membrane in rheumatoid arthritis. Reduced E-selectin and intercellular adhesion molecule 1 expression

OBJECTIVE

To investigate the effects of a 1,000-mg intravenous pulse of methylprednisolone succinate (MP) on cell adhesion molecule expression on the synovial vascular endothelium in patients with rheumatoid arthritis (RA).

METHODS

Sequential arthroscopic biopsy samples were taken before and 24 hours after MP administration (10 patients) and at the time of RA flare (2 patients) and after retreatment with MP (1 patient). Immunoperoxidase staining for E-selectin (CD62E), P-selectin (CD62P), intercellular adhesion molecule 1 (ICAM-1; CD54) and platelet-endothelial cell adhesion molecule (PECAM; CD31) was performed, and the staining was quantified by color video image analysis.

RESULTS

MP caused a rapid (within 24 hours) and substantial decrease in the expression of E-selectin on the synovial vascular endothelium, with a smaller reduction in ICAM-1 expression on synovial vascular endothelium and the synovial lining. There were no similar effects on synovial membrane P-selectin or PECAM expression.

CONCLUSION

A potential mechanism by which MP impairs neutrophil trafficking into inflamed RA joints might be by reducing E-selectin, and possibly, ICAM-1, expression in the synovial membrane.

Effect of omega-3 fatty acids on the progression of metastases after the surgical excision of human breast cancer cell solid tumors growing in nude mice

We showed previously that a diet rich in linoleic acid (LA), an omega-6 fatty acid, stimulates the growth and metastasis of human breast cancer cells in athymic nude mice. In contrast, diets supplemented with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), omega-3 fatty acids, exert suppressive effects. We have now assessed EPA and DHA as adjuvant nutritional therapy in the nude mouse model and compared the responses when the intervention was commenced 1 week before ("neoadjuvant") or immediately after ("postoperative adjuvant") surgical excision of the primary tumor. Female nude mice received a high-fat, 8% LA diet beginning 7 days before 10(6) MDA-MB-435 human breast cancer cells were injected into a thoracic mammary fat pad. As the tumor surface areas approached 0. 7 cm2, the mice were assigned to either continue on the LA-rich diet or to commence one containing 8, 4, or 2% EPA or DHA. Seven days later, the mammary fat pad tumors were excised; the mice still consuming the 8% LA diet were then allocated sequentially to either continue this diet or commence one of the six postexcision omega-3 fatty acid dietary interventions. Eight weeks later, the mice were necropsied and evaluated for local recurrence and lung metastases. Although there were no differences in the incidence of local recurrence between groups, EPA and DHA both inhibited the development of lung metastases. When the dietary interventions were commenced 7 days before surgery, the severity of lung metastasis was reduced by the two omega-3 fatty acids in a dose-dependent manner; at all three levels, the suppressive effects were statistically significant (P < 0.05). Postexcision EPA treatment produced small, statistically insignificant effects, but lung involvement was reduced significantly by feeding DHA at the 2 and 4% levels (P < 0. 05). Overall, these results suggest that omega-3 fatty acids may have a place as adjuvant nutritional therapy in breast cancer and particularly as part of a neoadjuvant regimen.

A comparison of survival of patients treated for AIDS-related central nervous system lymphoma with and without tissue diagnosis

PURPOSE

This is a retrospective review of the treatment outcome of radiation therapy (RT) in acquired immune-deficiency syndrome (AIDS) patients with presumed primary central nervous system (CNS) non-Hodgkin's lymphoma (NHL), with and without tissue verification.

METHODS AND MATERIALS

Twenty-seven patients with AIDS-related CNS NHL were treated between 1986 and 1992. They were divided into two groups. Group 1 consisted of nine patients with a positive histology for NHL. They were treated with dexamethasone (DXM) and whole brain RT. Group 2 consisted of 18 patients who, because of unique circumstances, were treated without histologic confirmation of NHL. Rapid clinical and/or radiologic response to DXM and whole-brain RT was interpreted as NHL.

RESULTS

For group 1, the response rate was 87.5%, mean survival 6.1 months, and median survival 4.5 months. For group 2, the response rate was 72.2%, mean survival 5.2 months, and median survival 4.5 months. The overall response rate was 76.9%, mean survival 5.8 months, and median survival 4.5 months.

CONCLUSIONS

In instances where a tissue diagnosis cannot be established, a positive response to an empiric trial of DXM and RT to 20 Gy may constitute presumptive evidence of NHL.

Educating nurses to undertake clinical supervision in practice

Alongside interest in the process of clinical supervision, there is a growing recognition of the need for education for practitioners undertaking the role of supervisor. This article describes a module accredited by the Welsh National Board and the University of Wales, Swansea, which was designed to achieve this aim and help practitioners design structures for supervision applicable to their practice settings. The structure and content of the module are described, as well as an evaluation of the first intake.

Critical contribution of beta chain residue 57 in peptide binding ability of both HLA-DR and -DQ molecules

Position 57 in the beta chain of HLA class II molecules maintains an Asp/non-Asp dimorphism that has been conserved through evolution and is implicated in susceptibility to some autoimmune diseases. The latter effect may be due to the influence of this residue on the ability of class II alleles to bind specific pathogenic peptides. We utilized highly homologous pairs of both DR and DQ alleles that varied at residue 57 to investigate the impact of this dimorphism on binding of model peptides. Using a direct binding assay of biotinylated peptides on whole cells expressing the desired alleles, we report several peptides that bind differentially to the allele pairs depending on the presence or absence of Asp at position 57. Peptides with negatively charged residues at anchor position 9 bind well to alleles not containing Asp at position 57 in the beta chain but cannot bind well to homologous Asp-positive alleles. By changing the peptides at the single residue predicted to interact with this position 57, we demonstrate a drastically altered or reversed pattern of binding. Ala analog peptides confirm these interactions and identify a limited set of interaction sites between the bound peptides and the class II molecules. Clarification of the impact of specific class II polymorphisms on generating unique allele-specific peptide binding "repertoires" will aid in our understanding of the development of specific immune responses and HLA-associated diseases.

Case report: Kaposi's sarcoma of the rectum--treatment with radiation therapy

The number of patients afflicted with the acquired immune deficiency syndrome (AIDS) is on the rise. About 30% of AIDS patients develop Kaposi's sarcoma. Although the skin is the most common site of involvement, lesions may encompass the gastrointestinal tract. The purpose of this report is to describe a patient with AIDS related Kaposi's sarcoma of the rectum, successfully treated with radiation therapy. We believe this to be a useful technique in the treatment of this condition.

Autism and medical disorders: a review of the literature

The authors reviewed all the population studies on autism published in the English language with particular reference to the rate of medical disorders. Seven studies met criteria for inclusion in the survey. The mean of possibly autism-related medical disorders in persons with autism across these studies was 24.4%. There was a trend for higher rates of medical disorders among subjects with severe mental retardation. The evidence in respect of atypical autism was equivocal, and the overall prevalence of medical disorders in this group was similar to that found in typical autism.

Increasing mortality from Creutzfeldt-Jakob disease in England and Wales since 1979: ascertainment bias from increase in post-mortems?

Creutzfeldt-Jakob disease (CJD) is a rare and fatal dementing illness. A direct link has been proposed between cattle infected with bovine spongiform encephalopathy (BSE) and a newly-identified variant of CJD. One possible explanation for the emergence of this new variant, together with a general increase in death due to classical CJD, would be ascertainment bias, due to an increase in the frequency of post-mortems in death attributed to dementia. This article uses national mortality records to look at trends in the proportion of deaths due to dementing illnesses for which a post-mortems was carried out. The results show an increase in deaths due to both CJD and other dementing illnesses, but a slight decrease in the proportion of post-mortems. We conclude that an increase in post-mortems is unlikely to explain the increase in deaths certified as due to CJD. Similarly, the appearance of the new variant of CJD since 1994 cannot easily be attributed to this form of ascertainment bias, in line with the conclusion reached by the Spongiform Encephalopathy Advisory Committee in March 1996.

Protein conformational changes during the bacteriorhodopsin photocycle. A Fourier transform infrared/resonance Raman study of the alkaline form of the mutant Asp-85-->Asn

Bacteriorhodopsin is a light-driven proton pump, which undergoes a photocycle consisting of several distinct intermediates. Previous studies have established that the M-->N step of this photocycle involves a major conformational change of membrane embedded alpha-helices. In order to further investigate this conformational change, we have studied the photocycle of the high pH form of the mutant Asp-85-->Asn (D85Nalk). In contrast to wild type bacteriorhodopsin, D85Nalk has a deprotonated Schiff base and a blue-shifted absorption near 410 nm, yet it still transports protons in the same direction as wild type bacteriorhodopsin (Tittor, J., Schweiger, U., Oesterhelt, D. and Bamberg, E. (1994) Biophys. J., 67, 1682-1690). Resonance Raman spectroscopy of D85Nalk and D85Nalk regenerated with retinal labeled at the C-15 position with deuterium reveals the existence of an all-trans configuration of the chromophore. Fourier transform infrared difference spectroscopy shows that the photocycle of this light-adapted form involves similar events as the wild type bacteriorhodopsin photocycle including the M-->N protein conformational change. These results help to explain the ability of D85Nalk to transport protons and demonstrate that the M-->N conformational change can occur even in the photocycle of an unprotonated Schiff base form of bacteriorhodopsin.

Asp 46 can substitute Asp 96 as the Schiff base proton donor in bacteriorhodopsin

Bacteriorhodopsin functions as a light-driven proton pump in the purple membrane of Halobacterium salinarium. A variety of studies have established that a proton is transferred over an approximately 10 A distance from Asp 96 to the retinylidene Schiff base during the M --> N transition of the bR photocycle. In order to further explore the mechanism of this Schiff base reprotonation, we compared the properties of the double mutant Thr 46 --> Asp/Asp 96 --> Asn (T46D/D96N), the single mutants Asp 96 --> Asn (D96N) and Thr 46 --> Asp (T46D), and wild-type bR. In contrast to D96N, which exhibits a very slow M decay, T46D/D96N has an M decay close to that of wild-type bR. FTIR difference spectroscopy detects bands in the carboxyl and carboxylate stretch region of T46D/D96N consistent with the deprotonation of Asp 46 during the M --> N transition. In addition, bands associated with structural changes of Asn 96 in the mutant D96N are absent in T46D/D96N. Resonance Raman spectroscopy provides evidence that both T46D/D96N and T46D have a long-lived N-like species in their photocycles. These data demonstrate that Asp 46 can substitute for Asp 96 as the proton donor group in the reprotonation pathway of the Schiff base during the M --> N transition. However, N decay is delayed in comparison to wild-type bR. This may be due to a partial block in the proton pathway leading from the cytoplasmic medium to Asp 46.

Using workshops to implement supervision

Clinical supervision is both topical and novel among many practice disciplines so it is important to consider how to take such an important initiative forward. This article describes a series of workshops designed to achieve this aim. The article focuses on the participants' perceptions of clinical supervision and its relevance to their practice environment. The authors also suggest ways to assist clinical staff further in this area.

Site-directed isotope labeling and FTIR spectroscopy: assignment of tyrosine bands in the bR-->M difference spectrum of bacteriorhodopsin

Fourier transform infrared difference spectroscopy has been used extensively to probe structural changes in bacteriorthodopsin and other retinal proteins. However, the absence of a general method to assign bands to individual chemical groups in a protein has limited the application of this technique. While site-directed mutagenesis has been successful in special cases for such assignments, in general, this approach induces perturbations in the structure and function of the protein, thereby preventing unambiguous band assignments. A new approach has recently been reported (Sonar et al., Nature Struct. Biol. 1 (1994) 512-517) which involves cell-free expression of bacteriorhodopsin and site-directed isotope labeling (SDIL). We have now used this method to re-examine bands assigned in the bR-->M difference spectrum to tyrosine residues. Our results show that out of 11 tyrosines in bR, only Tyr 185 is structurally active. This work further demonstrates the power of SDIL and FTIR to probe conformational changes at the level of individual amino acid residues in proteins.

Deficient antigen-presenting cell function in multiple genetic complementation groups of type II bare lymphocyte syndrome

The absence of HLA class II gene expression in type II bare lymphocyte syndrome (BLS) results from defective transcriptional activation of class II histocompatibility genes. Genetic studies have revealed that distinct defects in multiple trans-acting factors result in the immunodeficient BLS phenotype. We studied antigen-presenting cell (APC) function in DR-transfected BLS cells derived from multiple complementation groups. Each BLS cell line displayed the same defective APC phenotype: an inability to mediate class II-restricted presentation of exogenous protein antigens, and structurally altered class II alpha beta dimers. Expression of the HLA class II-like genes DMA and DMB, previously implicated in antigen presentation, was reduced or absent in the BLS cells. Fusion of BLS cells with cell line 721.174, which has a genomic deletion of HLA class II genes, coordinately restores class II structural gene and DM gene expression and a wild-type APC phenotype. Thus each of the molecular defects that silences class II structural gene transcription also results in a defective APC phenotype, providing strong evidence for coregulation of these two functionally linked pathways.

Influence of diets containing eicosapentaenoic or docosahexaenoic acid on growth and metastasis of breast cancer cells in nude mice

BACKGROUND

Diets rich in omega-6 polyunsaturated fatty acids (e.g., corn oil and other fats containing linoleic acid) stimulate the growth and metastasis of human breast cancer cells in athymic nude mice. On the other hand, diets containing fish oil, which is rich in omega-3 fatty acids (e.g., eicosapentaenoic and docosahexaenoic acids), exert suppressive effects.

PURPOSE

Our objective was twofold: 1) to compare the effects of diets containing linoleic acid with those of diets containing eicosapentaenoic acid and docosahexaenoic acid on the growth and metastasis of MDA-MB-435 human breast cancer cells in the nude mouse model and 2) to determine how such effects relate to observed changes in the chemical content of tumor fatty acids and eicosanoid production.

METHODS

Groups of 30 female athymic nude mice were fed 20% (wt/wt) fat diets containing either linoleic acid (8%) alone, linoleic acid (8%) plus eicosapentaenoic acid (4%) or docosahexaenoic acid (4%), or linoleic acid (4%) plus eicosapentaenoic acid (8%) or docosahexaenoic acid (8%) for 7 days before one million MDA-MB-435 cells were injected into a thoracic mammary fat pad. Diets were continued for 12 more weeks. Primary tumors were measured weekly. The mice were then killed and necropsied, and tumor tissues preserved. Cell membrane phospholipid fatty acid analyses and eicosanoid assays were performed. All P values represent two-tailed tests of statistical significance.

RESULTS

The growth of the primary tumors was retarded in mice fed the diets supplemented with eicosapentaenoic or docosahexaenoic acid compared with the growth of primary tumors in mice fed the 8% linoleic acid diet. Growth inhibition was statistically significant (P < .05) and most effective in association with the diets containing 8% of either omega-3 fatty acid, where tumors were smaller than those in the group fed the diet containing 8% linoleic acid alone at all time points after the 2nd week. The occurrence and severity of lung metastases were reduced in the groups fed omega-3 fatty acid (P < .05). In groups of mice fed eicosapentaenoic or docosahexaenoic acid, the representation of these acids in tumor phospholipids increased, with a statistically significant reduction in the concentrations of arachidonic acid (all groups), tumor 12- and 15-hydroxyeicosatetraenoic acid, and prostaglandin E. Levels of 5-hydroxyeicosatetraenoic acid and leukotriene B4 were unaffected by the omega-3 fatty acids.

CONCLUSION

The inhibitory effects of dietary fish oil on human breast cancer cell growth and metastasis in this model system are ascribable to its high eicosapentaenoic acid and docosahexaenoic acid content; the mechanism very likely involves suppression of tumor eicosanoid biosynthesis.

IMPLICATION

Future dietary intervention trials designed to reduce the risk of recurrence in the postsurgical breast cancer patient should include the evaluation of eicosapentaenoic acid and docosahexaenoic acid supplementation.

Site-directed isotope labeling and ATR-FTIR difference spectroscopy of bacteriorhodopsin: the peptide carbonyl group of Tyr 185 is structurally active during the bR-->N transition

The largest secondary structural change occurs in the bacteriorhodopsin (bR) photocycle during the M-->N transition. In this work site-directed isotope labeling (SDIL) and attenuated total reflection Fourier transform infrared (ATR-FTIR) difference spectroscopy were used to investigate this conformational change. L-Tyrosine containing a 13C isotope at the carbonyl carbon was selectively incorporated at Tyr 57, Tyr 147, and Tyr 185 by SDIL. This involves the cell-free expression of bR in the presence of Escherichia coli suppressor tRNA(CUATyr) aminoacylated with L-[1-13C]Tyr. ATR-FTIR difference spectroscopy reveals that of the 11 tyrosines, only the peptide carbonyl group of Tyr 185 undergoes a significant structural change during the bR-->N transition. Along with other spectroscopic evidence, this result suggests that the Tyr 185-Pro 186 region of the protein is structurally active and may function as a hinge which facilitates the tilt of the cytoplasmic portion of the F-helix in bacteriorhodopsin during the M-->N transition.