Insulin resistance and classic risk factors in type 2 diabetic patients with different subtypes of ischemic stroke

OBJECTIVE

In addition to classic risk factors (e.g., hypertension), insulin resistance is an important risk factor for the development of atherosclerosis. To investigate the risk factors for ischemic stroke in type 2 diabetes, we measured insulin sensitivity and several risk factors in 94 Japanese type 2 diabetic patients with different types of stroke.

RESEARCH DESIGN AND METHODS

Stroke was classified by magnetic resonance imaging (MRI) and magnetic resonance (MR) angiography into the following subtypes: 1) patients with normal MRI and MR angiography (NOR; n = 30), 2) patients with lacunar infarction (LAC; n = 28), 3) patients with atherothrombotic infarction (ATI; n = 22), and 4) patients with large-artery atherosclerosis (LAA; n = 14). Insulin sensitivity was assessed by the K index of the insulin tolerance test (KITT).

RESULTS

Patients with LAC, ATI, and LAA were significantly older and were more likely to be hypertensive than patients with NOR. Significantly higher insulin resistance was observed in patients with LAC, ATI, and LAA than in patients with NOR (KITT 2.21 +/- 0.17, 2.10 +/- 0.17, 2.19 +/- 0.25, and 3.25 +/- 0.21% per min, respectively, P < 0.001). Adjustment for age, sex, BMI, and duration of diabetes did not influence this result. Multiple logistical regression analysis showed that insulin resistance was an independent risk factor for all subtypes of ischemic stroke in type 2 diabetic patients. The same analysis showed that a high pulse pressure was a risk factor for LAC, postprandial C-peptide (hyperinsulinemia) was a risk factor for ATI, and longstanding hyperglycemia was a risk factor for LAA.

A gene for fluctuating, progressive autosomal dominant nonsyndromic hearing loss, DFNA16, maps to chromosome 2q23-24.3

The sixteenth gene to cause autosomal dominant nonsyndromic hearing loss (ADNSHL), DFNA16, maps to chromosome 2q23-24.3 and is tightly linked to markers in the D2S2380-D2S335 interval. DFNA16 is unique in that it results in the only form of ADNSHL in which the phenotype includes rapidly progressing and fluctuating hearing loss that appears to respond to steroid therapy. This observation suggests that it may be possible to stabilize hearing through medical intervention, once the biophysiology of deafness due to DFNA16 is clarified. Especially intriguing is the localization of several voltage-gated sodium-channel genes to the DFNA16 interval. These cationic channels are excellent positional and functional DFNA16 candidate genes.

Antithrombotic effect of SM-20302, a nonpeptide GPIIb/IIIa antagonist, in a photochemically induced thrombosis model in guinea pigs

SM-20302, a synthetic inhibitor of the fibrinogen receptor of platelets, has been shown to inhibit the platelet aggregation induced by various stimuli. In the present study, we performed ex vivo platelet aggregation studies by using heparinized platelet-rich plasma (PRP) as well as citrated PRP and compared the antiaggregatory activity with the in vivo antithrombotic efficacy of SM-20302. The oral administration of SM-20302 (0.3-10 mg/kg) to guinea pigs completely inhibited the ADP-induced ex vivo platelet aggregation in citrated PRP. In heparinized PRP, SM-20302 (1-10 mg/kg) showed a dose-dependent inhibition of ex vivo platelet aggregation, and it exhibited complete inhibition at a dose of 3 and 10 mg/kg, respectively. The concentration of ionized calcium in the citrated samples was approximately 35 times lower than that in heparinized samples. Chelation of ionized calcium caused an enhancement of the antiaggregatory activity of SM-20302 in guinea pig heparinized PRP in vitro. And addition of CaCl2 to citrated PRP reversed the enhancement. Citrate therefore appeared to enhance the inhibitory activity of SM-20302 by lowering the ionized calcium levels. We also examined the in vivo efficacy of SM-20302 in a photochemically induced femoral artery thrombosis model in guinea pigs. The photochemical injury of the endothelium of femoral artery resulted in a progressive decline in the blood flow. The oral administration of SM-20302 (0.1-3 mg/kg) produced a dose-dependent maintenance of the femoral artery patency and significantly prolonged the time to occlusive thrombus formation at a dose of 1 and 3 mg/kg, respectively. These results suggest that SM-20302 may be an orally active antithrombotic agent, and its in vivo antithrombotic efficacy appeared to correlate well with the ex vivo platelet inhibition in PRP prepared from heparinized blood but not in PRP anticoagulated with citrate.

Effects of trimetaphan-induced deliberate hypotension on human cochlear blood flow

In order to observe the reaction of cochlear blood flow (CBF) to trimetaphan (TMP)-induced hypotension, CBF was measured with laser-Doppler flowmetry in 7 human subjects during general anaesthesia for middle ear surgery. All subjects showed a decrease in mean arterial pressure (MAP) during intravenous infusion of TMP, followed by a gradual return to the baseline level after termination of the infusion. The CBF generally followed the MAP changes with the same pattern. Three of the seven subjects demonstrated a CBF change larger than the maximum MAP change, indicating the lack of a local autoregulatory mechanism in CBF. On the other hand, CBF changes were smaller in magnitude than the maximum change in MAP for the rest of the subjects, suggesting an autoregulatory mechanism in CBF. However, since the audiograms from these subjects indicated profound damage along the cochlear basal turn probably due to middle ear inflammation, concomitant vascular damage in this region offers another possible explanation for the inappropriate CBF changes. The present observations may also suggest that deliberately TMP-induced hypotension has a potentially harmful effect on CBF during otological surgery that attempts to preserve or improve hearing.

Relationships between apolipoprotein(a) phenotype and increase of lipoprotein(a) by troglitazone

Troglitazone is a new oral hypoglycemic agent that reduces insulin resistance in non-insulin-dependent diabetes mellitus (NIDDM). However, this agent increases serum lipoprotein(a) [Lp(a)], which is known as an atherogenic lipoprotein. The relationships between the response of Lp(a) to troglitazone and the apolipoprotein(a) [apo(a)] phenotype were investigated in this study. Nineteen NIDDM patients were treated with troglitazone for 4 weeks. Lp(a) increased significantly from 20.1+/-16.5 mg/dL to 44.1+/-31.9 mg/dL (P<.001) in all study patients. Lp(a) increased from 25.7+/-34.2 mg/dL to 50.1+/-38.7 mg/dL (P = .03) in patients with smaller apo(a) phenotypes (S1S4 to S2S4). Lp(a) also increased from 17.5+/-12.0 mg/dL to 41.3+/-29.6 mg/dL (P<.01) in patients with larger apo(a) phenotypes (S3 to S4). Therefore, the increase of Lp(a) by troglitazone may be independent of the apo(a) phenotype.

Removal of low-density lipoprotein from plasma by adsorption increases bradykinin and plasma nitric oxide levels in patients with peripheral atherosclerosis

Low-density lipoprotein (LDL) adsorption using a dextran sulfate cellulose column is brought about by electrostatic binding between the positive charges of apolipoprotein B in LDL and the negative charges of dextran sulfate cellulose. There is general agreement that the initial contact phase in the coagulation pathway may be activated by a negatively charged surface such as dextran sulfate cellulose, resulting in the generation of bradykinin. We investigated whether the increase in the generation of bradykinin during LDL adsorption is accompanied by the activation of endogenous production of nitric oxide (NO) in patients with peripheral atherosclerosis. LDL adsorption therapy was repeated ten times over a period of 3 months in ten peripheral atherosclerosis patients. Treatment significantly reduced serum total cholesterol and LDL cholesterol levels. This was associated with a significant improvement in Fontaine's classification and ankle pressure index. We also measured the kinin-kallikrein system and plasma levels of NO in the same patients. The results showed that coagulation factors of the intrinsic pathway including high-molecular-weight kininogen and prekallikrein decreased markedly after initial adsorption compared with the levels before treatment. There was a marked increase in bradykinin and NO concentrations after the initial adsorption, compared with their levels before adsorption. Our results suggest that the generation of bradykinin and increased plasma levels of NO may contribute to the improvement in peripheral circulation after LDL adsorption in peripheral atherosclerosis patients.

Organization and expression of basement membrane collagen IV genes and their roles in human disorders

Six distinct genes have been identified as belonging to the type IV collagen gene family. They can be organized into three sets, i.e., COL4A1/COL4A2, COL4A3/COL4A4, and COL4A5/COL4A6, which are localized on three different chromosomes in humans, 13, 2, and X, respectively. Within each set the genes are aligned head-to-head and their expression is regulated by bidirectional promoters between the genes. Transcriptional regulation of the COL4A1/COL4A2 set has been well characterized. The transcription of COL4A6 seems to be controlled by two alternative promoters. While collagen IV molecules composed of alpha1 and alpha2 chains are broadly distributed, molecules comprising combinations of the other four chains, alpha3-alpha6, are important components of specialized basement membranes. The precise chain composition of triple-helical molecules assembled from the alpha3-alpha6 chains is not entirely clear, but it is hypothesized that alpha3-alpha5 chains and alpha5 and alpha6 chains form heterotrimeric molecules. Several pieces of evidence indicate that alpha3/alpha4/alpha5 molecules and alpha5/alpha6 molecules are components of the basement membrane network. This helps explain the observation that the kidney and skin basement membranes from patients with Alport syndrome caused by mutations in the alpha5 coding gene, COL4A5, are defective in the alpha3, alpha4, and alpha6 chains together with the alpha5 chain. Large deletions involving the COL4A5 and COL4A6 genes have been found in rare cases of diffuse leiomyomatosis associated with Alport syndrome.

Effects of voglibose on glycemic excursions, insulin secretion, and insulin sensitivity in non-insulin-treated NIDDM patients

OBJECTIVE

To investigate the effects of voglibose, an alpha-glucosidase inhibitor, on daily glycemic excursions, insulin secretion, and insulin sensitivity in non-insulin-treated NIDDM patients.

RESEARCH DESIGN AND METHODS

An open prospective study was conducted in 27 NIDDM patients receiving diet therapy alone or treatment with a sulfonylurea drug. Of the study subjects, 14 patients were treated with voglibose; the remaining 13 patients served as the control group. The metabolic parameters were evaluated before treatment and at week 4 of treatment as follows: glycemic excursions by M-value and 1,5-anhydro-D-glucitol (1,5-AG), insulin secretion by area under the curve of daily serum insulin (AUCinsulin), and insulin sensitivity by the K index of the insulin tolerance test (KITT).

RESULTS

After the study treatment, HbA1c and plasma glucose in the patients who had received voglibose were comparable to those of patients in the control group. M-value was lower in the patients treated with voglibose than in the control subjects (5.7 +/- 0.9 vs. 9.8 +/- 1.2, P < 0.05). 1,5-AG was higher in the patients treated with voglibose than in the control subjects (12.2 +/- 1.0 vs. 8.2 +/- 0.7 micrograms/ml, P < 0.01). A statistically significant increase in AUCinsulin occurred after treatment with voglibose (2,223.5 +/- 390.6 to 1,546.7 +/- 303.4 pmol.l-1.h, P < 0.05), but no change occurred in the control group (2,364.5 +/- 315.4 to 2,464.2 +/- 269.3 pmol.l-1.h, P = 0.60). Insulin sensitivity (KITT) was improved to a statistically significant level in both the patients treated with voglibose and the patients in the control group. KITT in the patients after voglibose treatment was comparable to that of the control group (3.18 +/- 0.30 vs. 3.21 +/- 0.23%/min, P = 0.94).

CONCLUSIONS

The results suggest that voglibose lowers the daily glycemic excursions and inhibits overwork of the pancreatic beta-cells but has little effect on insulin sensitivity in NIDDM patients.

Topoisomerase I and II consensus sequences in a 17-kb deletion junction of the COL4A5 and COL4A6 genes and immunohistochemical analysis of esophageal leiomyomatosis associated with Alport syndrome

Diffuse esophageal leiomyomatosis (DL), a benign smooth-muscle-cell tumor, is characterized by abnormal cell proliferation. DL is sometimes associated with X-linked Alport syndrome (AS), an inherited nephropathy caused by COL4A5 gene mutations. COL4A5 is tightly linked, in a head-to-head fashion, to the functionally related and coordinately regulated COL4A6 gene. No X-linked AS cases are due to COL4A6 mutations, but all DL/AS cases are always associated with deletions spanning the 5' regions of the COL4A5/COL4A6 cluster. Unlike the COL4A5 breakpoints, those of COL4A6 are clustered within intron 2 of the gene. We identified a DL/AS deletion and the first characterization of the breakpoint sequences. We show that a deletion eliminates the first coding exon of COL4A5 and the first two coding exons of COL4A6. The breakpoints share the same sequence, which, in turn, is closely homologous to the consensus sequences of topoisomerases I and II. Additional DNA evidence suggested that the male patient is a somatic mosaic for the mutation. Immunohistochemical analysis using alpha-chain-specific monoclonal antibodies supported this conclusion, since it revealed the absence of the alpha5(IV) and alpha6(IV) collagen chains in most but not all of the basement membranes of the smooth-muscle-cell tumor. We also documented a similar segmental staining pattern in the glomerular basement membranes of the patient's kidney. This study is particularly relevant to the understanding of DL pathogenesis and its etiology.

Up-regulation of iNOS mRNA expression and increased production of NO in human monoblast cell line, U937 transfected by HTLV-I tax gene

We investigated the mRNA expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) in human T cell lymphotropic virus type I (HTLV-I) p40tax-transfected U937 cells, a human monoblast cell line. Transfection of HTLV-I p40tax U937 cells induced up-regulation of iNOS mRNA expression and subsequent NO production. Furthermore, interferon gamma (IFN-gamma) stimulation of HTLV-I p40tax-transfected U937 cells enhanced iNOS mRNA expression and NO production. The kinetics of iNOS mRNA expression and NO production indicated maximal effect at 24 and 48 hours, respectively, after culture with or without IFN-gamma. These findings suggest that HTLV-I p40tax can act as a transactivator of NO production in cells of Mo/M phi lineage. To what extent this mechanism may be involved in the pathogenesis of HTLV-I-associated diseases warrants further investigation.

Insulin resistance and arteriosclerosis obliterans in patients with NIDDM

OBJECTIVE

To investigate the risk factors for arteriosclerosis obliterans (ASO) in NIDDM, we measured insulin sensitivity and other risk factors including lipoprotein(a) [Lp(a)] in NIDDM patients with and without ASO.

RESEARCH DESIGN AND METHODS

A case-control study in 100 patients with NIDDM, 35 with and 65 without ASO, was performed. Insulin sensitivity was assessed by the short insulin tolerance test's K index (KITT). Duration of diabetes, a history of smoking, prevalence of hypertension, prevalence of coronary artery disease (CAD), serum C-peptide, 24-h urinary C-peptide, serum lipids, and Lp(a) were compared in the two groups.

RESULTS

Age, BMI, HbA1c, and fasting plasma glucose were comparable in the two groups. Patients with ASO were significantly more insulin resistant than patients without ASO (KITT 2.16 +/- 0.16 vs. 3.00 +/- 0.13%/min, P < 0.0001, respectively), had a longer duration of diabetes (10.3 +/- 1.2 vs. 7.5 +/- 0.8 years, P < 0.05), included a greater number of smokers (68.6 vs. 40.0%, P < 0.01), had a higher prevalence of CAD (60.0 vs. 16.9%, P < 0.01), and had a greater percentage of insulin therapy (48.6 vs. 29.2%, P < 0.05). However, urinary and serum C-peptide levels, serum lipids, and Lp(a) levels were comparable in the two groups. Multiple logistic regression analysis indicated that a history of smoking (odds ratio 3.70, P = 0.011), insulin resistance (odds ratio 3.68, P < 0.001), and an elevated Lp(a) level (odds ratio 1.03, P = 0.020) were independently related to ASO. When patients with CAD were removed from the logistic regression analysis, insulin resistance was most strongly related to ASO (odds ratio 20.9, P < 0.001).

CONCLUSIONS

Patients with ASO were characterized by a higher prevalence of CAD, a greater percentage of smokers, a greater percentage of insulin therapy, and a higher insulin resistance than were patients without ASO. Insulin resistance, especially, may be the most powerfully related to ASO. Lp(a) may play a minor role in the development of ASO.

Structure of the human type XIX collagen (COL19A1) gene, which suggests it has arisen from an ancestor gene of the FACIT family

Type XIX collagen is a newly discovered member of the FACIT (fibril-associated collagens with interrupted triple helices) group of extracellular matrix proteins. Based on the primary structure, type XIX collagen is thought to act as a cross-bridge between fibrils and other extracellular matrix molecules. Here we describe the complete exon/intron organization of COL19A1 and show that it contains 51 exons, spanning more than 250 kb of genomic DNA. The comparison of exon structures of COL19A1 and other FACIT family genes revealed several similarities among these genes. The structure of exons encoding the noncollagenous (NC) 1-collagenous (COL) 1-NC 2-COL 2-NC 3-COL 3-NC 4 domain of the alpha1(XIX) chain is similar to that of the NC 1-COL 1-NC 2-COL 3-NC 3 domain of the alpha2(IX) chain except for the NC 3 domain of alpha1(XIX). The exons encoding the COL 5-NC 6 domain of alpha1(XIX) are also similar to those of the COL 3-NC 4 domain of alpha1(IX) chain. Previously, COL19A1 was mapped to human chromosome 6q12-q14, where COL9A1 is also located. Likewise, the present work shows that the mouse Col19a1 gene is located on mouse chromosome 1, region A3, where Col9a1 has also been mapped. Taken together, the data suggest that COL19A1 and COL9A1 (Col19a1 and Col9a1) were duplicated from the same ancestor gene of the FACIT family. Three CA repeat markers with high heterozygosity were found in COL19A1. These markers may be useful for linkage analysis of age-related inheritable diseases involved in eyes and/or brain.

Glucose tolerance, insulin secretion, and insulin sensitivity in nonobese and obese Japanese subjects

OBJECTIVE

To investigate the relative contributions of insulin secretion and insulin resistance to the development of glucose intolerance in Japanese subjects.

RESEARCH DESIGN AND METHODS

A cross-sectional study of 756 Japanese subjects (530 nonobese, 226 obese) was performed. A 75-g oral glucose tolerance test (OGTT) was given, and subjects were classified according to the World Health Organization (WHO) criteria (normal glucose tolerance [NGT], impaired glucose tolerance [IGT], and diabetes). Early-phase insulin secretion was assessed by the insulinogenic index (the ratio of the increment of insulin to that of plasma glucose [PG] 30 min after a glucose load [delta IRI0-30 min/delta PG0-30 min]). Total insulin secretion was assessed by mean immunoreactive insulin (IRI) during the OGTT, and insulin resistance was assessed by use of the homeostasis model [HOMA(R)].

RESULTS

Early-phase insulin secretion was significantly decreased in IGT, compared with patients with NGT, in both the nonobese and obese subjects (0.70 +/- 0.05 vs. 0.37 +/- 0.03, P < 0.01 and 1.36 +/- 0.19 vs. 0.73 +/- 0.08, P < 0.01, respectively). However, mean IRI and HOMA(R) in both nonobese and obese subjects with IGT and NGT were not statistically different. Subjects with diabetes showed a significant decline in early-phase and total insulin secretion and a significantly higher level of insulin resistance than did subjects with IGT. When the fasting glucose (FPG) exceeded 100 mg/dl, early-phase insulin decreased progressively. The graphed relationship between FPG and mean IRI did not show an inverted U-shape, and mean IRI decreased progressively when FPG exceeded 100-130 mg/dl. The pattern of changes in insulin secretion and insulin resistance associated with the progression of glucose intolerance was similar in both the nonobese and obese subjects.

CONCLUSIONS

The worsening from NGT to IGT in Japanese subjects may be associated with a decrease in early-phase insulin secretion in nonobese as well as in obese subjects. Hyperinsulinemia in IGT is not common. We suggest that impaired early-phase insulin secretion may be the initial abnormality in the development of glucose intolerance in Japanese people. Insulin resistance may be a consequence of hyperglycemia and/or obesity.

Demonstration of the biological activity of peptide fragments related to human and rat hippocampal cholinergic neurostimulating peptide (HCNP)

Human and rat hippocampal cholinergic neurostimulating peptides (HCNPs) are 54.5% homologous; both stimulate acetylcholine synthesis in rat medial septal nuclei cultures. This in vitro system was used to test the bioactivity of short peptides containing human or rat HCNP sequences. Peptides with sequences corresponding to the N-termini and middle regions of both, and to the shared three C-terminal residues were not active. Tetrapeptides and hexapeptides whose C-terminus is this common sequence enhanced acetylcholine production, indicating that the minimum consensus sequence for HCNP activity is X-Gly-Pro-Leu.

[Tympanic electrocochleography with disposable electrode]

Extratympanic recording of electrocochleography (ECochG) has played an important role in the differential diagnosis of inner ear diseases. We used a special electrode, which was wrapped in a cotton ball at the tip and covered with a silicon sheath over the entire length, and recorded ECochG from the tympanic membrane (tympanic ECochG). Our method was found to be more convenient and less traumatic than recording with an ear canal electrode. Tympanic ECochG records from 10 normal volunteers showed no influence of iontophoretic anesthesia on the tympanic membrane. The effects on the conductive hearing mechanism were negligible. The input-output curve of the action potential (AP) by click stimuli was fairly stable and comparable to that obtained with transtympanic recording. We performed tympanic ECochG in patients with Meniere's disease or other sensory hearing loss, and compared the amplitude ratios of the summating potential (SP) and AP (SP/AP ratio) with those in normal hearing subjects. The SP/AP ratios in patients with Meniere's disease were significantly increased, an observation consistent with the results of other studies. The SP/AP ratio was also elevated in patients with autoimmune sensory hearing loss or perilymphatic fistula. Based on the results of the present study, we speculate that it is possible to diagnose an inner ear disorder by comparing the tympanic ECochG findings with not only records from normal subjects, but also the contralateral record of tympanic ECochG from the same subject. We conclude that tympanic ECochG using disposable electrodes can provide useful information on inner ear function, because of its convenience, non invasiveness and safety in clinical use. We found tympanic ECochG to be useful in the glycerol dehydration test and for monitoring inner ear function during acoustic neurinoma surgery.

Increased nitric oxide levels in patients with rheumatoid arthritis

OBJECTIVES

We determined whether serum levels of nitric oxide (NO) correlate with disease activity of rheumatoid arthritis (RA) and inflammatory cytokines by measuring the serum and synovial fluid (SF) concentrations of NO in patients with RA and patients with osteoarthritis (OA) and healthy subjects.

METHODS

The concentration of NO in each sample was determined by chemiluminescence. Cytokine levels were determined using sandwich enzyme-linked immunoassays.

RESULTS

The mean serum concentration of NO was significantly higher in patients with RA (293.4 +/- 108.5 nM) compared with that of patients with OA (33.4 +/- 4.0, p < 0.01) and healthy subjects (35.9 +/- 4.5, p < 0.01). The mean SF concentration of NO (3218 +/- 73.7, p < 0.01) was significantly higher than that of serum in patients with RA. Furthermore, levels of serum NO, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were significantly higher in patients with RA with active disease compared to patients with inactive disease. Serum NO levels correlated significantly with the morning joint stiffness, the number of tender or swollen joints, and CRP. Furthermore, NO levels correlated significantly with serum TNF-alpha and IL-6 levels.

CONCLUSIONS

Our results suggest that increased endogenous NO synthesis reflects abnormalities of immunoregulation in the joints of patients with RA.

Isolation and structure of the COL4A6 gene encoding the human alpha 6(IV) collagen chain and comparison with other type IV collagen genes

The genes COL4A5 and COL4A6, coding for the basement membrane collagen chains, alpha 5(IV) and alpha 6(IV), respectively, are located head-to-head in close proximity on human chromosome Xq22, and COL4A6 is transcribed from two alternative promoters in a tissue-specific fashion (Sugimoto M., Oohashi T., and Ninomiya Y. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 11679-11683). Immunofluorescence studies using alpha chain-specific antibodies demonstrated that the two genes are expressed in a tissue-specific manner (Ninomiya, Y., Kagawa, M., Iyama, K., Naito, L., Kishiro, Y., Seyer, J. M., Sugimoto, M., Oohashi, T., and Sado, Y. (1995) J. Cell Biol. 130, 1219-1229). We report here for the first time the isolation and the structural organization of the human COL4A6 gene. The entire gene presumably exceeds 200 kilobase pairs and contains 46 exons. Exons 1' and 1 encode the two different 5'-UTRs and the two amino-terminal parts of of the signal peptide. The carboxyl part of the signal peptide and the 7 S domain are coded for by the following 6 different exons, 2-7, whereas the exons 7-42 encode the central COL 1 domain, which contains the Gly-X-Y repeats. The last three exons, 43-45, encode the carboxyl-terminal NC1 domain. Sizes of more than a half of the exons of the gene are the same as those of Col4a2 but quite different from those of COL4A5. Within the COL4A6 gene we found three CA repeat markers that can be used for allele detection. The detailed structure of the COL4A6 gene and the high heterozygosity microsatellite markers located within the gene will be useful for linkage analysis and familial diagnosis of diseases caused by mutations of this gene.

Removal of LDL from plasma by adsorption reduces adhesion molecules on mononuclear cells in patients with arteriosclerosis obliterans

BACKGROUND

There is increasing evidence that immune processes are important in the development of atherosclerosis. We investigated whether low density lipoprotein (LDL) adsorption therapy affected serum cytokine levels and the expression of adhesion molecules on peripheral blood mononuclear cells (lymphocytes and monocytes) in patients with arteriosclerotic obliterance (ASO).

METHODS AND RESULTS

LDL adsorption therapy was repeated ten times over a period of three months in ten ASO patients. The total serum cholesterol and LDL cholesterol levels were significantly reduced at the end of therapy. This was associated with a significant improvement in Fontaine's classification and ankle pressure index. We also measured serum levels of inflammatory cytokines (interleukin-1 beta (IL-1 beta), IL-6 and tissue necrosis factor alpha (TNF-alpha)) and expression of adhesion molecules (lymphocyte function-associated antigen 1 alpha (LFA-1 alpha), LFA-1 beta, CD2, very late antigen (VLA)-4, VLA-5 and CD44) on mononuclear cells in the same patients and a group of healthy subjects. Serum levels of all inflammatory cytokines were markedly higher in ASO patients compared with healthy subjects, but there was no significant difference in the level before and after LDL adsorption. VLA-4 expression on CD3+ cells, but not of other adhesion molecules, was markedly higher in ASO patients compared with healthy subjects. LDL adsorption caused a significant reduction in CD2, VLA4 and VLA-5 expression on CD3+ cells. Furthermore, VLA-4 and VLA-5 expression on monocytes diminished significantly after LDL adsorption.

CONCLUSIONS

Our results indicate that LDL adsorption-induced immunoregulation is mediated by an indirect stimulatory effect on the immune system. The results suggests that improved peripheral circulation produced by LDL adsorption may reflect improved immune dysfunctions of atherosclerotic lesions in ASO patients.

Serum cytokines in patients with rheumatoid arthritis. Correlation of interferon gamma and tumor necrosis factor alpha with the characteristics of peripheral blood mononuclear cells

Serum cytokines such as interleukin 1 beta (IL-1 beta), interferon gamma (IFN-gamma), and tumor necrosis factor alpha (TNF alpha) were measured in 40 patients with rheumatoid arthritis (RA). In the 40 patients studied, serum IL-1 beta was detected in 5 patients, IFN-gamma in 10 patients, and TNF alpha in 20 patients. The IL-1 beta-positive group showed increased values of activity indices compared to the IL-1 beta-negative group. Values of serum IFN-gamma correlated well with the number of peripheral blood lymphocytes and CD3+ cells and with the percentage of CD3+ CD26+ cells. Values of serum TNF alpha correlated positively with the number of peripheral blood monocytes and the percentage of CD3+ HLA-DR+ and CD3+ CD25+ cells. These results indicated that serum IL-1 beta in RA patients reflects the activity of RA, while the serum IFN-gamma and TNF alpha in RA patients may be related to circulating activated lymphocytes and monocytes, respectively.

Increment of CD8S6F1 cells in synovial fluid from patients with rheumatoid arthritis

OBJECTIVE

To investigate the role of CD8 cell subsets in the pathogenesis of rheumatoid arthritis (RA) and the phenotypes of T cells adherent or non-adherent to the target cells (endothelial cells and synovial cells) pre-treated with IL-1 beta.

METHODS

The expression of S6F1 on CD8 cells and that of an activation marker on CD8 cells and CD8 cell subsets was evaluated in specimens of peripheral blood and synovial fluid obtained from 15 patients with RA and 10 with osteoarthritis (OA) using a two- or three-colour immunofluorescence method for analysis.

RESULTS

The percentage of CD8S6F1 cells among CD8 cells in synovial fluid was significantly greater than that of peripheral blood. Synovial fluid from RA patients had a greater percentage of CD8S6F1 cells compared with either peripheral blood of matched patients or synovial fluid of OA patients. The percentage of CD8HLA-DR cells in synovial fluid was markedly greater than that in paired samples of peripheral blood in patients with RA. In the CD8S6F1 cells from both groups of patients, synovial fluid showed an increased percentage of HLA-DR cells compared with peripheral blood. Similar results were observed in CD8 cells lacking S6F1 expression (CD8S6F1-) from both groups of patients. There was no significant difference in the percentage of HLA-DR cells between CD8S6F1 and CD8S6F1- cell populations in peripheral blood. In contrast with peripheral blood, in synovial fluid of RA patients the percentage of HLA-DR cells in the CD8S6F1 cell population was markedly greater than that in the CD8S6F1- population. However, the percentage of HLA-DR cells in both cell populations was similar in synovial fluid of OA patients. In both the endothelial and the synovial cell adhesion assays, the percentage of CD8S6F1 among CD8 cells and the mean fluorescence intensity of S6F1 antigen on CD8S6F1 cells were significantly greater in the adherent T cell population than that in the non-adherent T cell population.

CONCLUSION

These results suggest that increased expression of S6F1 antigen and the increased percentage of HLA-DR cells on CD8 cells in synovial fluid may be responsible for the migration of these cells into inflamed synovial tissues, and for cellular interactions between these cells and synovial cells or the extracellular matrix.

Interleukin 4 increases human synovial cell expression of VCAM-1 and T cell binding

OBJECTIVE

The effects were studied of interleukin 4 (IL-4) on T cell-synovial cell adhesion and on the expression of adhesion molecules on the surface of synovial fibroblast-like cells.

METHODS

The adhesion of T cells toward the synovial cells were measured by 51chromium-labelled adhesion assay. The expression of adhesion molecules on synovial cells were analysed by flowcytometry.

RESULTS

Stimulation of synovial cells with IL-4 increased T cell-synovial cells adhesion in a time- and dose-dependent manner. IL-4 considerably enhanced the expression of VCAM-1 on the surface of synovial cells, but not the expression of ICAM-1 and ELAM-1. The combination of IL-1 beta and IL-4 had no effect on the expression of ICAM-1 or VCAM-1 on the surface of synovial cells. The increased adhesion of T cells to IL-4 stimulated synovial cells was inhibited significantly by adding anti-VCAM-1 or anti-CD29 monoclonal antibody. Furthermore, anti-VLA-4 alpha or the combination of anti-VLA-4 alpha and anti-VCAM-1 antibodies blocked completely T-cell binding to IL-4 stimulated synovial cells.

CONCLUSIONS

These results suggest that the increased adhesion of T cells to IL-4-stimulated synovial cells is mediated by VLA-4/VCAM-1 pathway.