Relapse of porphyria cutanea tarda after treatment with phlebotomy or 4-aminoquinoline antimalarials: a meta-analysis.

BACKGROUND: Porphyria cutanea tarda (PCT) is the most common human porphyria. It is caused by hepatic deficiency of uroporphyrinogen decarboxylase activity, which is acquired in the presence of multiple susceptibility factors. PCT presents clinically with cutaneous blistering photosensitivity and is readily treatable with either repeated phlebotomy or 4-aminoquinoline antimalarials. OBJECTIVES: To perform a systematic review and meta-analysis to compare the effectiveness of these quite different treatment approaches, especially on relapse rates (RRs) after achieving remission. METHODS: Published studies that included follow-up for at least 1 year after treatment of PCT were included. The primary study outcome was PCT relapse. Pooled data are reported as the RRs per person-year of follow-up with 95% confidence intervals (CIs). RESULTS: Of 375 articles identified as pertaining to PCT treatment, 12 were eligible for analysis. Of these, five used high-dose 4-aminoquinoline regimens (two combined with phlebotomy and three without phlebotomy), five used low-dose 4-aminoquinoline regimens and three used phlebotomy. RRs during the year after treatment were similar for the high- and low-dose 4-aminoquinoline groups (35-36%) and lower in the phlebotomy group (20%). The pooled RRs with their 95% CIs were 8·6 (3·9-13·3) per 100 person-years in the high-dose 4-aminoquinoline group, 17·1 (8·9-25·3) per 100 person-years in the low-dose 4-aminoquinoline group and 5·1 (0·5-10·6) per 100 person-years in the phlebotomy group. Subgroup and sensitivity analyses showed similar results. CONCLUSIONS: Clinical or biochemical RRs ranged from 5 to 17 per 100 person-years after remission of PCT. Relapses were somewhat more frequent after remission with 4-aminoquinoline regimens than after remission following phlebotomy. Prospective studies are needed to define better how often relapses occur with these treatments after documenting both clinical and biochemical remission of PCT.

Cell transfer technique for constructing cytological microarrays for immunocytochemical analysis.

OBJECTIVE: To evaluate the utility of a proposed cell transfer technique for constructing cytological smear microarrays and its potential applications in multiplex immunocytochemical (ICC) staining. METHODS: Ninety-six cytology smears, including two pericardial effusions, 22 ascites and 72 pleural effusions, were transferred to a 33-plex cytological microarray. Paired staining of thyroid transcription factor-1 (TTF-1) and calretinin ICC was performed in duplicate slides. RESULTS: Most of the smeared cells selected for transfer could be removed from the original slides with a minimal loss of cells and with no change in morphological features or immunoreactivity. Comparison of the staining results with immunohistochemical staining results, clinical history and histopathological reports available for each patient revealed that TTF-1 was positive in 32/33 metastatic pulmonary adenocarcinomas (PACs), 1/15 non-pulmonary adenocarcinomas and 0/45 benign effusions. The ICC results for TTF-1 on a transferred cytological microarray revealed high (97%) sensitivity and high (96.7%) specificity for the detection of metastatic PAC. CONCLUSION: Cytology microarrays can be constructed by transferring cells from serous fluid cytological smears, and cells transferred to the microarray retain their morphological integrity and immunoreactivity. Researchers can use the technique for simultaneous immunostaining of multiple specimens in studies of neoplastic or non-neoplastic diseases when available tissue samples are limited.

Meta-analysis: the impact of oral anti-viral agents on the incidence of hepatocellular carcinoma in chronic hepatitis B.

BACKGROUND: Five oral nucleos(t)ide analogues are available to treat chronic hepatitis B (CHB). With the availability of newer agents, their efficacy on incidence of hepatocellular carcinoma (HCC) is not well described. AIM: To determine the efficacy of oral anti-viral agents in reducing HCC risk in relationship with other known factors. METHODS: Published studies of at least 20 CHB patients treated with an oral anti-viral agent and followed for >2 years were analysed for incidence of HCC per 100 person years follow-up. RESULTS: Pooled homogeneous data from six studies showed lamivudine (LAM) treatment (n = 3306) to reduce HCC risk by 51% compared with no treatment (n = 3585) (3.3 vs. 9.7 per 100 person years, P < 0.0001). Pooled data from 49 studies (23 with LAM; 16 with adefovir; and 10 with entecavir, tenofovir or telbivudine) of 10 025 treated patients showed HCC incidence of 1.3 per 100 person years, independent of the agent used. Patient age >50 years and hepatitis B virus-DNA detectability at HCC diagnosis increased risk of HCC by twofold with a 10-fold higher risk among patients with cirrhosis compared with chronic hepatitis. Meta-regression showed patient age, study location (Eastern vs. Western) and type of study (randomised or not) contributed to heterogeneity. CONCLUSIONS: Lamivudine treatment significantly reduces the incidence of HCC compared with no treatment. However, HCC still develops at a rate of 1.3 per 100 patient years in CHB patients receiving an oral anti-viral agent. This finding highlights the need for continued HCC surveillance, particularly in CHB patients with inadequate viral suppression, older age and cirrhosis.

Genetic and functional analyses describe a novel 730delG mutation in the KEL gene causing K0 phenotype in a Taiwanese blood donor.

AIMS/OBJECTIVES: The purpose of this study was to explore the molecular basis of the K0 phenotype of a Taiwanese blood donor found to have anti-Ku alloantibodies. BACKGROUND: With respect to Kell blood group antigens, almost all Taiwanese have the (K-, k+) phenotype. MATERIALS AND METHODS: Alloantibody identification and KEL antigen typing were performed. Enzymatic function assays were carried out to detect the Kell glycoprotein on RBCs. The KEL genes were sequenced to detect genetic variation. To determine the origin of this novel allele, family studies were conducted. RESULTS: The alloantibody was identified as anti-Ku. The donor was typed K0 . The KEL gene-sequencing data revealed that this K0 donor is a compound heterozygote with two different null alleles. He bears a novel 730delG mutation in one allele. Family studies suggested that the donor inherited the 730delG mutation from his father. The endothelin-converting activity assay indicated that his RBCs had no functional Kell glycoprotein. Other family members who had only one null allele with the 730delG mutation had the phenotype (K-, k+). CONCLUSION: For blood transfusion safety, it is important to establish an effective screening algorithm to identify rare phenotypes, such as the K0 phenotype, and to establish a database of rare blood groups.

Capsule endoscopy with PILLCAM ESO for detecting esophageal varices: a meta-analysis.

AIM: The aim of the present study was to perform meta-analysis of studies that compare diagnostic capabilities of esophageal capsule endoscopy (ECE) against conventional esophago-gastro-duodenoscopy (EGD) in detecting esophageal varices. METHODS: A literature search is done for studies that compared the performance of ECE and EGD in screening and surveillance of esophageal varices. Data was extracted to estimate the pooled sensitivity, pooled specificity, positive diagnostic ratio, negative diagnostic ratio and diagnostic odds ratio. RESULTS: We included 9 studies and total number of patients was 631. There were 12 capsule failures so data was available for 619 patients. The pooled sensitivity and specificity of CE for detecting esophageal varices were 83% and 85% respectively. The pooled positive likelihood and negative likelihood ratios are 4.09 and 0.25, respectively. Pooled diagnostic odds ratio was 24.92. CONCLUSION: In our meta- analysis PillCam ESO performed well in detecting esophageal varices but it was not comparable to EGD; it can be an acceptable alternative in certain situations but cannot be recommended to replace EGD.

Areca nut extracts increased expression of inflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and interleukin-8, in peripheral blood mononuclear cells.

BACKGROUND AND OBJECTIVE: Cytokines represent a central role in inflammatory tissue destruction and regulate the immune responses that may govern the progression of periodontal diseases. This study investigated the effects of areca nut extracts on the expression of inflammatory cytokines, tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and interleukin-8 in peripheral blood mononuclear cells. The role of oxidative stress of areca nut extracts was also examined using curcumin. MATERIAL AND METHODS: The expression of cytokines in peripheral blood mononuclear cells treated with extracts of ripe areca nut or extracts of tender areca nut was analyzed using enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction. RESULTS: Both extracts of ripe areca nut (< or = 40 microg/mL) and extracts of tender areca nut significantly enhanced the production of tumor necrosis factor-alpha and interleukin-1beta in peripheral blood mononuclear cells in a dose-dependent and time-dependent manner. The kinetics of mRNA expression of both cytokines was also enhanced by areca nut extracts. The stimulatory effects of areca nut extracts on the secretion of tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and interleukin-8 and on the mRNA expression of tumor necrosis factor-alpha, interleukin-1beta and interleukin-6 at 4 h of incubation were reduced by curcumin (20-50 microm). However, the level of interleukin-8 transcripts was not affected by curcumin. Moreover, interleukin-1beta induction by extracts of tender areca nut, but not by extracts of ripe areca nut, was weakened by 10 microm curcumin. The inhibitory effects of curcumin may vary with different cytokines and with different areca nut extract treatments. CONCLUSION: The complex cytokine profile induced by areca nut extracts-treated peripheral blood mononuclear cells implied the possibility of enhanced local inflammation and altered immune functions by the areca chewing habit. The inhibitory effects of curcumin on cytokine expression suggested that oxidative stress might be involved in areca nut extracts-associated immune alteration.

Renal allograft injury is associated with urinary tract infection caused by Escherichia coli bearing adherence factors.

Urinary tract infections are the most common infection in renal transplant patients and Escherichia coli (E. coli) is the most common clinical isolate. Although acute allograft injury (AAI) secondary to urinary tract infection (UTI) has been reported, the incidence of AAI associated with UTI, the virulence factors express by uropathic E. coli and whether virulence factors are associated with renal allograft outcome have not been described. We collected E. coli from our renal transplant patients with UTI, determined O:H serotypes, P and Dr fimbriae expression and the clinical presentation and allograft function during the UTI and post-UTI period. Pyelonephritis occurred in 40% of our patients, 82% of which had AAI (>20% increase in SCr). Sixty-two percent of E. coli isolates that expressed P fimbriae were associated with AAI, whereas only 29% that did not express P fimbriae had AAI (p = 0.03). The pattern of P fimbriae and O serotypes differed from reported isolates, as the P fimbriae PapG class II and the O25 serotype were the most common. Dr adhesin was expressed on 7 isolates, including 2 of 3 with urosepsis. We propose a unique pattern of uropathogenic serotypes and adherence factors contribute to acute allograft injury in renal transplant patients with UTI.

Autoimmune IDDM in a sporadic MELAS patient with mitochondrial tRNA(Leu(UUR)) mutation.

We report a 28-year-old young male with MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) presenting with two previous episodes of stroke-like manifestation, lactic acidosis and mitochondrial cardiomyopathy. He was also affected with insulin-dependent diabetes mellitus (IDDM), as diagnosed by the experience of diabetic ketoacidosis (DKA), and dependence on insulin therapy. On admission, the serum lactate level was found to be increased to 5.4 mmol/l, and plasma glucose level to 7.9 mmol/l with haemoglobin A1c 8.4%, while he was using insulin 26-30 units per day. Physical examination revealed a short stature male of height of 150 cm and weight of 49 kg. Mild mental retardation with bilateral sensorineural hearing impairment was observed. After glucagon stimulation, C-peptide levels rose from 0.46 nmol/l to 0.53 nmol/l, indicative of impaired insulin secretion. Anti-glutamate decarboxylase (anti-GAD) antibody was positive. In addition, human leucocyte associated antigen (HLA) typing showed DR3 and DR4, suggesting the strong contribution of autoimmunity to the pathogenesis of IDDM in this patient. Moreover, the result of a treadmill exercise test was positive due to inferior wall myocardial ischaemia. Cardiac catheterization and endomyocardial biopsy disclosed a normal coronary angiogram and confirmed the diagnosis of mitochondrial cardiomyopathy. Molecular genetic analysis of his family revealed a sporadic occurrence of mitochondrial DNA (mtDNA) mutation at base pair (bp) 3243. The degree of heteroplasmy of mtDNA mutation from a total of 19 passages of skin-derived fibroblasts from this patient showed a slightly downward trend. This extremely rare case of sporadic MELAS syndrome with autoimmune IDDM harbouring mtDNA mutation highlights the possible pathogenetic role of mtDNA mutations in autoimmune disease.

Multivariate profile of smoking in Southeast Asian men: a biochemically verified analysis.

BACKGROUND: Cigarette smoking prevalence rates among Southeast Asian males are among the highest reported in comparison with other ethnic male groups in the United States. The objective of this study is to profile current smokers, former smokers, and never smokers among Southeast Asian males, based on subject characteristics. METHODS: Southeast Asian (Cambodian, Laotian, and Vietnamese) males residing in the Greater Columbus, Ohio, area were surveyed, utilizing culturally sensitive instruments and interviewers, with respect to demographic and acculturation variables. All subjects were biochemically verified by collecting a saliva sample at the time of the interviews. RESULTS: Those Southeast Asian males who quit smoking tended to be older, employed, more assimilated into the U.S. culture, and of Cambodian ethnicity. The current smokers, relative to never smokers, tended to be older, not in the labor force, traditionally oriented to their native culture, less educated, and of Laotian or Vietnamese ethnicity. CONCLUSIONS: Specific strategies for smoking cessation programs would indicate more intense, and possibly different, efforts be directed at Southeast Asian males of Laotian and Vietnamese ethnicity who are younger, unemployed and less assimilated into the U.S. culture. On the other hand, smoking prevention programs would target those individuals who are at highest risk of smoking.

Cloning and sequencing of complete thyrotropin receptor transcripts in pretibial fibroblast culture cells.

Pretibial fibroblasts are considered to be targets of autoimmune attack in pretibial myxedema. A possibility of the pathogenesis of pretibial myxedema is that T cells, reacting with thyrotropin (TSH) receptor, will be targeting to the pretibial fibroblasts where, in the presence of antigen (TSH receptor), they will secrete various cytokines and stimulate fibroblasts to secrete glycosaminoglycans. We have demonstrated that TSH and TSH receptor antibody can bind to fibroblasts and the presence of RNA encoding the extracellular domain of the TSH receptor in fibroblasts derived from skin lesions of two patients with pretibial myxedema. The present study was designed to determine whether there are complete TSH receptor transcripts in pretibial fibroblasts obtained from patients with pretibial myxedema. RNA was prepared from pretibial fibroblasts obtained from 11 patients with pretibial myxedema and from four normal subjects, then reverse-transcribed by polymerase chain reaction using three sets of primers (-11/+8 and +754/+773; +353/+373 and +1265/+1285; +1000/+1017 and +2284/+2301). The overlapped 2312 bp cDNA sequence was expected to contain the genetic sequences of the signal peptide (+1/+60), extracellular domain (+61/+1254), transmembrane domain (+1255/+2046), and cytoplasmic domain (+2047/ +2292) of the TSH receptor. The sequences were determined using dideoxy sequencing method. All of the 2312 nucleotide sequences in 15 samples were consistent with the reported TSH receptor sequence of transcripts in thyroid. These data suggest that the complete TSH receptor transcripts are very possible to be present in the fibroblasts derived from pretibial skin.

Hydration, not silicone, modulates the effects of keratinocytes on fibroblasts.

Topical silicone gel or silicone cream with occlusive dressing has proved to be an efficacious method for the treatment and prevention of hypertrophic scars and keloids, but how this action is triggered remains unknown. Hydration of the epidermis and/or the cellular effects of the released low-molecular-weight silicone oil have been suggested as possible mechanisms. In order to further elucidate the mechanism, we used an in vitro keratinocyte-fibroblast coculture model to investigate the cellular effects of silicone and hydration. In this model, the condition of clinical usage of topical silicone gel or cream or the condition of hydration exerted by occlusive dressing could be mimicked. The model consisted of two chambers separated by a semipermeable membrane, in which a fully differentiated stratified epithelium is present in the upper chamber and medium and monolayer fibroblasts are located in the lower chamber. The keratinocytes were nourished from the basal side only, while the apical surface was submerged in silicone oil, paraffin, Hanks' balanced salt solution, or medium (hydration); or it was exposed to air (control). In the hydration-treated group, the proliferation of fibroblasts measured as [3H]thymidine incorporation and their collagen, glycosaminoglycan production was significantly inhibited when compared with the controls, but exposure of the keratinocyters to silicone oil or paraffin did not influence fibroblast behavior. The results suggest that hydration, not silicone, modulates the in vitro keratinocyte-fibroblast interaction. This may be one possible mechanism by which topical silicone or occlusive dressing treatment may affect the development of hypertrophic scars and keloids.

TSH and TSH receptor antibody-binding sites in fibroblasts of pretibial myxedema are related to the extracellular domain of entire TSH receptor.

The role of TSH receptor antibodies in the pathogenesis of pretibial myxedema is still unclear. This study was designed to determine whether patients with pretibial myxedema had higher serum titers of TSH receptor antibodies, and whether there were TSH and TSH receptor antibody-binding sites on plasma membranes of fibroblasts derived from the skin of pretibial myxedema. If there were, were the binding sites similar to the TSH receptor? The TSH receptor antibodies were determined with radioreceptor assay in 20 normal subjects, 18 hyperthyroid Graves' disease patients without ophthalmopathy, 26 hyperthyroid Graves' disease patients with ophthalmopathy, and 11 patients with pretibial myxedema associated with Graves' ophthalmopathy. TSH and TSH receptor antibody-binding sites were studied on plasma membranes of fibroblasts cultured from the skin of pretibial myxedema with radioreceptor assay. RNA was also extracted from the fibroblasts of pretibial myxedema and reverse transcribed using random primers as the primers for cDNA synthesis. The resulting cDNAs were subjected to amplification by polymerase chain reaction with the use of a set of primers spanning the 5' region (+256/+275 and +616/+635) and the 3' region (+1819/+1838 and +2405/+2424) of the TSH receptor cDNA (+1 transcription start codon). They were further identified by Southern blot hybridization, with the probe spanning the 5' region (+272/+612) and the 3' region (+1908/+2268) of the TSH receptor cDNA (+ 1 transcription start codon), and sequencing. The results showed that patients with pretibial myxedema had higher titers of TSH receptor antibodies in the serum. TSH and TSH receptor antibody-binding sites were present on plasma membranes of fibroblasts derived from the skin of pretibial myxedema patients and related to the extracellular domain of the TSH receptor. These data suggest a common antigenic site in the skin and in the thyroid as a putative target for TSH receptor antibodies or lymphocytes of Graves' disease.

Pentoxifylline inhibits the proliferation and glycosaminoglycan synthesis of cultured fibroblasts derived from patients with Graves' ophthalmopathy and pretibial myxoedema.

Excessive amounts of glycosaminoglycans accumulate in the extraocular muscles of patients with Graves' ophthalmopathy and in the affected skin of patients with pretibial myxoedema. It is widely accepted that fibroblasts are the sources of glycosaminoglycan synthesis. Pentoxifylline, an analogue of the methylxanthine theobromine, inhibits the proliferation and certain biosynthetic activities of fibroblasts derived from normal human skin and from skin of patients with some fibrotic disorders. Our objective was to determine whether pentoxifylline has similar effects on fibroblasts derived from patients with Graves' ophthalmopathy and pretibial myxoedema and could serve as a candidate for the treatment of these manifestations. Fibroblasts from the extraocular muscles of two patients with Graves' ophthalmopathy and normal extraocular muscles of two subjects with strabismus, as well as the affected skin of two patients with pretibial myxoedema were cultured in vitro in the presence and absence of pentoxifylline to assay its effect on the proliferation of fibroblasts and their production of glycosaminoglycans. In subconfluent fibroblast cultures, pentoxifylline treatment caused a dose-dependent inhibition of serum-driven fibroblast proliferation. In confluent fibroblast cultures both in the presence and absence of serum, exposure to pentoxifylline similarly resulted in a dose-dependent inhibition of glycosaminoglycan synthesis for all these different kinds of fibroblasts. These findings may form the rationale for a clinical trial using pentoxifylline for the treatment of Graves' ophthalmopathy and pretibial myxoedema.

Characterization of a human keratinocyte cell line immortalized by human papillomavirus 16 DNA.

A human keratinocyte cell line was established by transfecting neonatal foreskin keratinocytes of a Chinese with human papillomavirus (HPV) 16 DNA. As evidenced by the prolonged life span, the clone formation from a single cell, the piling up after prolonged culturing without passage and the chromosomal aneuploidy, this cell line possesses the biological characteristics of immortalization. The reason for obligatory growth requirements on epidermal growth factor (EGF) is not clear. The partial growth requirement on hydrocortisone for this immortalized cell line suggests that the glucocorticoid responding element of HPV 16 may play a role in cell immortalization. The constant over-expression of keratin 19 in this and other HPV 16 immortalized squamous epithelia indicates that it may serve as a useful marker for the potential malignant transformation of squamous epithelial cells. This immortalized cell line provides a model for investigating the factors and cofactors involved in carcinogenesis and differentiation of human epithelial cells.

Growth of human melanocytes from suction blister of localized vitiligo patient and from foreskins of newborns and adults by modified culture medium.

We report on the culturing of melanocytes from suction blisters from the uninvolved skin of localized (focal and segmental) vitiligo patients and from the foreskins of newborns and adults, over a long period of time using a modified culture medium composed of F-12 medium supplemented with insulin (5 mg/mL), cholera toxin (40 ng/mL), transferrin (5 mg/mL), hydrocortisone (1 mM), epithelial growth factor (20 ng/mL), endothelial cell growth supplement (ECGS) (15 mg/mL), retinol (1 x 10(-7) M), 12-o-tetradecanoyl-phorbol-13 acetates (TPA) (85 nM), and 1% fetal calf serum (FCS). This method may be used in in vitro studies on normal human melanocytes and for study of the difference between melanocytes of normal individuals and of those with vitiligo. The ability to culture melanocytes from localized vitiligo, and the inability to grow those of generalized vitiligo with this system reconfirms the difference in the pathogenesis of various types of vitiligo. Thus, culturing may be used for differentiating localized vitiligo from generalized vitiligo and may be used to guide the mode of treatment when vitiligo has just started to develop and only a few depigmented patches have appeared. The results of studies on seeding density effect and serial Dopa reaction on the melanocytes of normal individuals reveal that the use of tyrosinase activity as the assessment parameter requires the use of melanocytes cultured for less than five months at a seeding density of less than 4 x 10(4) cells/cm2. Enlarged and heavily pigmented cells, senescent cells, were observed after very long-term culture (one year and four months).(ABSTRACT TRUNCATED AT 250 WORDS)

Growth and characterization of normal human keratinocytes in F12 serum-free medium.

In a F12 medium supplemented with epidermal growth factor (20 ng/ml), insulin (5 micrograms/ml), transferrin (5 micrograms/ml), hydrocortisone (1 microM), cholera toxin (40 ng/ml), endothelial cell growth supplement (15 ng/ml) and retinoic acid (1 x 10(-7) M) on Vitrogen coated culture dishes, normal adult and newborn human foreskin keratinocytes were cultured for 4- and 2-time with population doublings (PD) accumulated as 8 and 12, respectively. The cells grown in this medium possessed a basaloid, undifferentiated and hyperproliferating nature, with a population doubling time of about 24 hours at early passage. Between the 1st and 2nd subcultures, cell proliferation was the most active. Delaying the time of first subculture lowered the rate of cell proliferation. The keratin of the cultured cells was studied by immunoblotting and revealed the presence of permanent keratin markers of the human skin (AE1 50 kDa and AE3 58kDa) as well as a relatively high intensity of a proliferating marker (AE1 48 kDa) and a relatively low intensity of a differentiation marker (AE3 67 kDa).

The proliferative effect of platelets and hyperlipidemic serum on stationary primary cultures.

Outgrowths from explants of aortic media which have become stationary in the presence of a medium containing 10% normal serum have been studied. Homologous hyperlipidemic serum and especially its low density lipoprotein fraction has been shown to induce a second episode of proliferation in these cultures. Cell proliferation was evaluated by direct measurement of cell colony size and/or incorporation of [3H]thymidine visualized by autoradiography. The possibility has been investigated that the increase in arterial smooth muscle cell proliferation produced by hyperlipidemic serum might actually be due to a platelet factor present in that serum. Platelet-poor and platelet-rich sera were prepared from hyperlipidemic donors and added in a concentration of 5% to the culture medium. Both were equally effective in inducing proliferation; on the other hand, the addition of platelets from either hyperlipidemic or normolipidemic animals had no additive effect. The proliferation-stimulating effect of hyperlipidemic serum occurred even when the stationary cultures were maintained in a medium containing platelet-poor plasma serum for 2 weeks, prior to the addition of hyperlipidemic serum also derived from platelet-poor plasma. It is concluded that the proliferative effect of hyperlipidemic serum on stationary primary cultures does not depend on the presence of platelet-derived material. The implications of these observations on plaque formation are discussed.