Site-specific differences in the fatty acid composition of abdominal adipose tissue in an obese population from a Mediterranean area: relation with dietary fatty acids, plasma lipid profile, serum insulin, and central obesity.

BACKGROUND: Abdominal obesity is associated with coronary risk, although causality is not well established. OBJECTIVE: In an obese Mediterranean population, we measured the fatty acid composition of adipose tissue, its relation with dietary fatty acids and central fat deposition, and its influence on plasma lipids and insulin. DESIGN: Adipose tissue samples were obtained from 84 obese patients (29 men, 55 women) aged 30-70 y (body mass index, in kg/m(2): 27-35). We measured concentrations of insulin and lipids in plasma and fatty acids in subcutaneous, omental, and perivisceral fat. Dietary fatty acid intake was assessed with a 7-d diet record. RESULTS: The population studied was normolipidemic and normoinsulinemic. There were important differences in fatty acid composition between tissue sites: saturated fatty acids were higher and monounsaturated fatty acids were lower in perivisceral than in subcutaneous fat (P < 0.05). Significant correlations were found for oleic, linoleic, alpha-linolenic, and total n-6 polyunsaturated fatty acids between the subject's habitual diet and adipose tissue composition. Oleic and n-3 fatty acids from adipose regions were negatively correlated with apolipoprotein B and triacylglycerols; adipose tissue 22:1n-9, 20:2n-6, stearic acid, and eicosapentaenoic acid were positively correlated with HDL and apolipoprotein A; and adipose tissue myristic acid was negatively correlated with apolipoprotein A (P < 0.05). Central obesity was positively associated with n-6 polyunsaturated fatty acids and inversely associated with monounsaturated fatty acids and n-3 polyunsaturated fatty acids in adipose tissue (P < 0.05). CONCLUSION: The differences found in the composition and metabolism of perivisceral, omental, and subcutaneous fats may indicate that their atherogenic capacities also differ.

Rocuronium-induced neuromuscular blockade is affected by chronic phenytoin therapy.

Patients receiving chronic anticonvulsant therapy have been reported to show resistance to certain nondepolarizing neuromuscular blockers. In this study, the effects of chronic phenytoin therapy on the onset, duration, and recovery of rocuronium action was assessed. Thirty-six patients scheduled for various neurosurgical procedures were studied: 18 receiving chronic phenytoin therapy (Group I) and 18 controls (Group II). Rocuronium 0.6 mg/kg (2 x DE95) was administered after induction of general anesthesia with 4-6 mg/kg thiopental sodium and 3-5 microg/kg intravenous (IV) fentanyl. Maintenance anesthesia consisted of N2O in O2, 0.5% end-tidal isoflurane, and a fentanyl infusion. Neuromuscular block was monitored with acceleromyography of the adductor pollicis-brevis muscle by using a TOF-GUARD Biometer monitor (Biometer International A/S, Odense, Denmark). According to the amplitude of the first response of train-of-four, neither the lag time nor the onset time differed between the two groups. However, the recovery index was significantly shorter in patients chronically treated with phenytoin (mean recovery index: control group, 8.3 +/- 1.7 minutes; phenytoin group, 6.7 +/- 2.3 minutes; P < .05). In addition, the times of recovery to 10%, 25%, 75%, and 90% of the baseline response were also significantly shorter in the phenytoin group than in the control group. We conclude that the duration of action of rocuronium and the recovery index were affected by chronic phenytoin therapy.

Altered HLA class I expression in non-small cell lung cancer is independent of c-myc activation.

We studied the expression of major histocompatibility complex class I antigens in 59 bronchogenic carcinomas, as well as in pneumocytes and epithelial respiratory cells distant from the tumor. We observed in all cases that normal lung tissue expressed major histocompatibility complex class I antigens, while this expression was completely lost in 16 tumors (27%). The defect in HLA gene expression affected both heavy chain and beta 2-microglobulin, as demonstrated by the null reactivity with the monoclonal antibodies GRH1, W6/32, and HC10. Selective underexpression was detected in 1 tumor for HLA-A locus antigens and in 3 tumors for HLA-B locus antigens. Southern blot analyses of major histocompatibility complex class I genes were performed in 20 tumor tissue specimens and 6 cell lines. No class I gene rearrangements were detected using HLA coding and locus specific noncoding probes. We also used the Southern blot method to investigate the possible relationship between c-myc amplification and HLA class I antigens in non-small cell lung cancers and detected no apparent amplification in 20 tumor tissue specimens (5 negative for HLA class I antigens) and 6 cell lines (3 with decreased expression). Northern blot analysis revealed no relationship between c-myc mRNA levels and specific mRNA for HLA-A and HLA-B antigens in cell lines with imbalanced HLA-A or HLA-B expression.

Molecular analysis of MHC-class-I alterations in human tumor cell lines.

Molecular characterization of HLA-class-I expression was investigated in human tumor cell lines at the protein and mRNA levels using locus-specific monoclonal antibodies (MAbs) and probes. Some cell lines exhibited a differential expression of HLA-A and HLA-B products and also showed differences in the inducibility of HLA-class-I genes by gamma-IFN. Thus, gamma-IFN stimulation induced predominantly HLA-B mRNA in the HeP-2 cell line, which showed imbalances in basal levels of HLA-A and HLA-B expression. This unequal inducibility of HLA genes may imply that locus-specific regulatory mechanisms are involved in the expression of individual HLA products. The specific mechanism controlling the differential expression of HLA subsets appears to be independent of c-myc activity. Northern blot analysis found no relationship between c-myc mRNA levels and specific mRNA for HLA-A and HLA-B antigens.

Lack of MHC class I antigens and tumour aggressiveness of the squamous cell carcinoma of the larynx.

A series of 60 primary laryngeal and hypopharyngeal tumours, 24 lymph node metastases and normal tissue were evaluated in frozen sections for the expression of MHC class I antigens, using monoclonal antibodies and the APAAP technique. We found 13 tumours presenting total HLA-ABC loss, five with selective loss of HLA-A antigens and one with absence of HLA-B antigens. These losses were statistically associated with clinical and pathological parameters, such as T stage, degree of differentiation, scores according to the Jakobsson and Glanz grading systems and degree of leukocytic infiltration. Our results lead us to the following conclusions: (a) HLA class I losses were found in a group of tumours showing greater aggressiveness and worse prognosis; (b) these alterations in expression were not associated with an increased metastatic potential. Thus, the absence of HLA molecules in laryngeal tumours is related to greater local aggressiveness, and the loss of class I antigens seems to constitute an adaptive tumour mechanism to avoid the different anatomical and immunological barriers within the larynx.

Relationship of 4F2 antigen with local growth and metastatic potential of squamous cell carcinoma of the larynx.

The 4F2 antigen is a cell-membrane glycoprotein which arises early in the G0-G1 phases of the cell cycle. This molecule is present in all established human cell lines and most malignant human cells. The authors used an indirect immunophosphatase method to study 50 squamous cell carcinomas of the larynx and ten lymph-node metastases, corresponding to six primary tumors, for 4F2 expression. The tumors showed several patterns of 4F2 staining which were correlated with different behaviors and prognoses of the neoplasms. Three different patterns (no staining, peripheral staining, and diffuse 4F2 expression) are described as are their relationships with metastatic behavior of the carcinomas. Tumors with metastases were found only in the third group (P = 0.0001). These results led to the following conclusions: (1) the 4F2 antigen is present in squamous cell carcinomas; (2) its distribution reflects the tumor-spreading pattern; and (3) it correlates with differentiation and metastatic behavior.

K-ras mutations (codon 12) are not involved in down-regulation of MHC class-I genes in colon carcinomas.

Fifty-eight colorectal carcinomas were studied for HLA class-I antigen expression and for the presence of point mutations in codons 12 and 61 of the K-ras gene. Eight carcinomas were completely negative for class I by the APAAP technique. Analyses using the polymerase chain reaction (PCR) method, together with selective hybridization using mutation-specific synthetic oligonucleotides, demonstrated K-ras mutations in 14 cases (24.1%), all of them in codon 12. None of the mutations corresponded to the negative cases for class-I HLA antigen expression. We did not observe any correlation between K-ras mutations and the extent of tumor differentiation.

HLA-DR expression is associated with excellent prognosis in squamous cell carcinoma of the larynx.

We studied class II antigen expression and tumor-infiltrating leukocytes (TIL) in tissue sections of 69 squamous cell carcinomas of the larynx and 24 lymph node metastases in the neck. HLA-DR expression was found only in eight well-differentiated, highly keratinizing squamous cell carcinomas comprising seven of the verrucous variety and one ventriculosaccular tumor. None of the metastases was positive for DR antigen. Neither primary tumors nor autologous metastases stained for DP or DQ antigens. DR-positive tumors shared a peculiar pattern of TIL composed mainly of T cells, most of which belonged to the cytotoxic/suppressor subset, and B cells. These neoplasms had in common a slow rate of growth, and are considered low-grade carcinomas in the literature. We conclude from our study that HLA-DR expression seems to characterize tumors with a prominent infiltrate and an excellent prognosis.

Presence of HPV 16 sequences in laryngeal carcinomas.

Human papillomavirus types HPV 16 and HPV 11 DNA sequences were analyzed in normal and neoplastic tissues of the larynx, using the technique of polymerase chain reaction (PCR). An amplified region of E6 ORF was hybridized with 3' end-labelled oligonucleotide probe. Twenty six out of 48 (54%) squamous-cell carcinomas, and 3 out of 3 verrucous-cell carcinomas hybridized with HPV 16 DNA sequences, whereas we did not detect HPV 11 sequences. HPV 16 DNA sequences were also found in normal, autologous mucosa and lymphnode metastases, although these were absent in other tissues analyzed. HPV-16-positive tumors were most frequently poorly differentiated squamous-cell carcinomas.

MHC class I and II antigens on gastric carcinomas and autologous mucosa.

The expression of HLA class I and II antigens was analysed in 30 primary gastric carcinomas, 27 autologous lymph node metastases and 25 autologous gastric mucosae. We used an immune alkaline phosphatase technique on cryostatic sections and mAbs directed against HLA class I monomorphic determinants, HLA-B locus-specific products and HLA-DR, -DP and -DQ molecules. In addition HLA class I genes were analysed in tumour tissue and compared by Southern blots with the RFLP from autologous mucosa using locus-specific HLA probes. Finally the infiltrating mononuclear cells were studied on gastric tumours and adjacent mucosa with mAbs defining CD4, CD8 and CD11b differentiation antigens. The results obtained showed that three out of 27 primary gastric carcinomas completely lack HLA-ABC antigens (10%). In addition, two primary tumours presented a variable expression. The remaining 22 tumours presented a homogeneous positive HLA class I expression. Interestingly, when the autologous mucosa was analysed, only 12 out 25 specimens were homogeneously stained with mAbs against HLA class I antigens, suggesting that this tissue may lack the expression of HLA antigens before becoming malignant. Indeed, the majority of the gastric carcinomas studied presented a higher HLA-ABC antigenic expression than autologous mucosa. Finally, the HLA expression observed in the primary tumour was similar to that observed in autologous metastases. As a second part of the study we have found a direct relationship between the expression of HLA-DR antigens in mucosa and the intensity of inflammatory infiltration. This relationship was not maintained in the tumour tissue. In the mucosa the CD4-positive T cell was the predominant lymphocyte, while it was CD8 in the HLA-DR-positive tumours. Finally the RFLP of class I genes did not show any differences in any of the cases when compared with autologous mucosa. We included in these studies DNAs from HLA class I-negative tumours, HLA positive and HLA-B-negative ones.

Histocompatibility antigens in primary and metastatic squamous cell carcinoma of the larynx.

A series of 38 primary laryngeal and hypopharyngeal tumours, 15 lymph-node metastases and normal tissue were evaluated in frozen sections for the expression of MHC class I and II antigens, using monomorphic monoclonal antibodies (MAbs) to HLA-ABC, beta 2-microglobulin, DR, DP, DQ, HLA-B and polymorphic HLA-ABC antigens. Normal distant mucosa of larynx reacted to anti-class I antibodies but not to anti-class II. In 9 primary tumours (23.7%) HLA class I antigens were not observed. The remaining 29 showed a strong reaction to not observed. The remaining 29 showed a strong reaction to anti-HLA-ABC (heavy chain) and anti-beta 2-microglobulin, although in 3 cases out of 29 no staining was observed with anti-HLA-B locus-specific MAbs. These selective losses were confirmed using the corresponding anti-HLA polymorphic MAbs. For HLA class II molecules, only DR was observed in 3 of 38 cases. Defective HLA class I expression statistically correlates with high scores according to Jakobsson's criteria for histopathological tumour grading. Loss of HLA-ABC antigens was most frequent among the cases with poor differentiation (6/8 cases). On the contrary, class II antigen expression was correlated with a well differentiated pattern and a more favourable prognosis (p less than 0.001). We have found differences in HLA class I expression when comparing primary tumours and autologous metastases (3/9 cases). Immunoprecipitation and SDS-PAGE of class I antigens, Northern and Southern blot analyses of MHC class I genes were performed. We have not detected class I gene rearrangement using HLA coding and locus-specific non-coding probes. However, we have found a class I transcription defect that corresponds with a class-I-negative phenotype.

Effects of postnatal age and diet on the fatty acid composition of plasma lipid fractions in preterm infants.

Diet and postnatal age effect the fatty acid composition of plasma and tissue lipids. This work was designed as a transversal study to evaluate the changes in the fatty acid composition of plasma phospholipids, cholesteryl esters, triglycerides and free fatty acids in preterm infants (28-35 weeks gestational age), fed human milk (HM) and milk formula (MF) from birth to 1 month of life. Sixteen blood samples were obtained from cord, and 19 at 6-8 h after birth, 14 at 1 week and 9 at 4 weeks from HM-fed infants and 18 at 1 week and 14 at 4 weeks from MF-fed ones. Groups had similar mean birth weight, gestational age and sex ratio. The MF provided 69 kcal/dl and contained 16% of linoleic acid and 1.3% of alpha-linolenic acid on the total fat. Plasma lipid fractions were extracted and separated by thin-layer chromatography and fatty acid methyl esters were quantitated by gas liquid chromatography. In plasma phospholipids, linoleic acid (18:2 omega 6) continuously increased from birth to 1 month of age, but no changes were seen as related to type of diet; polyunsaturated fatty acids greater than 18 carbon atoms of both the omega 6 and omega 3 series (PUFA omega 6 greater than 18 C and omega 3 greater than 18 C) dropped from birth to 1 week and continued to decrease in MF-fed infants until 1 month; eicosatrienoic (20:3 omega 6), arachidonic (20:4 omega 6) and docosahexaenoic (22:6 omega 3) were the fatty acids implicated. In cholesteryl esters palmitoleic (16:1 omega 7) and oleic (18:1 omega 9) acids decreased from birth to 1 month and linoleic acid increased and arachidonic acid dropped, especially in MF fed infants. In triglycerides, palmitic, palmitoleic and stearic acid (18:0) decreased during the first month of life; oleic acid remained constant and linoleic acid increased in all infants, but arachidonic acid decreased only in those fed formula. Free fatty acids showed a similar behavior in fatty acids and in plasma triglycerides. Preterm neonates seem to have special requirements of long-chain PUFA and adapted MF should contain these fatty acids in similar amounts to those of HM to allow the maintenance of an adequate tissue structure and physiology.