A pilot study to evaluate the treatment of basal cell carcinoma with 5-fluorouracil using phosphatidyl choline as a transepidermal carrier

BACKGROUND

In certain situations, successful topical therapy of basal cell carcinoma (BCC) without the inconvenience, risk, and expense of surgery would be of great value to patients. Placing 5-fluorouracil (FU) in an appropriate carrier may solve these problems. Phosphatidyl choline (PC) penetrates effectively throughout the epidermis of shaved rabbits and may be able to carry small water-soluble molecules such as nucleotides across lipid barriers when applied topically.

OBJECTIVE

We propose that employing PC as a vehicle will facilitate the penetration of 5-FU and increase efficacy as compared to petrolatum-based 5-FU cream.

METHODS

This pilot study is a double-blinded and randomized therapeutic trial. Thirteen patients with 17 biopsy-proven, moderate thickness BCCs were randomized to receive either cream A (5% 5-FU in a PC vehicle) or cream B (Efudex(R): 5% 5-FU in a petrolatum base). Patients applied cream A or cream B twice a day for 4 weeks. The patients underwent an excisional biopsy of the treated BCC site at week 16.

RESULTS

There was a 90% cure rate (9/10) in those lesions treated with 5% 5-FU in PC cream and a 57% cure rate (4/7) in those treated with 5% 5-FU in a petrolatum-based cream.

CONCLUSION

Although the study was unable to detect any statistically significant differences in outcome between the study groups, this small pilot study shows preliminary findings which may indicate an increase in the short-term eradication of BCC using a PC-based vehicle as compared to conventional petrolatum-based formulations.

The hypocholesterolemic and antiatherogenic effects of topically applied phosphatidylcholine in rabbits with heritable hypercholesterolemia

To test possible hypocholesterolemic and antiatherogenic effects of transdermally administered phosphatidylcholine (PC), we applied a 33% solution of PC in ethanol containing 0.01% butylated hydroxytoluene as antioxidant, to the shaved back of a strain of inbred rabbits which spontaneously developed hypercholesterolemia (serum cholesterol above 110 mg/dl) and severe atherosclerotic lesions especially in the aortic arch. After the topical application of PC, increases of choline-containing phospholipids in blood were observed, reaching a plateau in 24-48 hr. There were significant reductions in serum cholesterol and LDL cholesterol in the treated animals 2-3 weeks after the treatment. Atherosclerotic lesions in the aortic arch were clearly less severe in the animals repeatedly treated with topical PC. The hypocholesterolemic and antiatherogenic effects of topical PC could be the result of increased cholesterol efflux from extrahepatic tissues and enhanced reverse cholesterol transport.

A micro enzymic method for determination of choline-containing phospholipids in serum and high density lipoproteins

A micro method is described for the assay of choline-containing phospholipids in serum and high density lipoproteins (HDL) using an automated microtiter plate reader. The method is adapted from the enzymic method of Takayama, Itoh, Nagasaki, and Tanimuzu (Clin. Chim. Acta 79, 93-98, 1977) using phospholipase D, choline oxidase, and peroxidase coupled with the color generating system phenol and 4-amino-antipyrine. The micro method requires 5 microL of serum or HDL sample, and 42 samples can be assayed in duplicate in one run using a 96-well flat-bottom microtiter plate. The reaction is linear up to 400 mg/dL and the lower limit of detection is 0.25 mg of choline-containing phospholipids per assay. The coefficient of variation within an assay is 0.86-0.79%, and day-to-day variation is 0.9-1.5%. Results obtained by the micro method are in excellent agreement with those obtained by the procedure of Takayama et al. (r = 0.997). The supernatant left after removal of low density lipoproteins and very low density lipoproteins from serum and precipitation with heparin/manganese chloride reagent can thus be conveniently used for the micro assay of choline phospholipids in HDL.

Correlates of atherosclerosis in coronary arteries of patients undergoing angiographic evaluation

The correlations between lipid and lipoprotein measurements and other risk factors of coronary artery disease were evaluated in 101 men undergoing coronary angiography. Clinically significant disease was present in 75 patients, whereas 24 had no observable lesions and 2 had minimal lesions. Comparisons of individual lipid and lipoprotein levels were nearly all significantly different between patients with and patients without clinically significant disease; however, no single variable could predict the presence of disease among patients. Logistic regression analysis identified five factors: apolipoprotein A-I, apolipoprotein B, diabetes, age, and family history of heart disease, which account for most of the differences between the two patient groups. These results could have important implications for the evaluation and management of patients suspected of having coronary atherosclerosis.

Effect of dialysate composition on the lipid response to L-carnitine supplementation

Cumulative carnitine losses through dialysis membranes may worsen hyperlipidemia during long-term hemodialysis. However, carnitine supplementation has not shown a consistent beneficial response in hyperlipidemia. We have compared in a double-blind, cross-over study the effect of dialysate buffer composition (acetate or bicarbonate) on the serum lipid response to L-carnitine supplementation during hemodialysis. We studied nine patients (mean age, 19 years; range, 14 to 23) with hyperlipidemia undergoing maintenance hemodialysis. Plasma levels of carnitines and lipids, including total and HDL cholesterol (HDL-C) and triglycerides (TG), were measured at baseline and monthly intervals after receiving 2 grams of L-carnitine or placebo added to dialysis bath for three months. One month of carnitine supplementation in acetate hemodialysis significantly reduced plasma TG (230 +/- 95 to 136 +/- 20 mg/dl; P less than 0.05) and elevated HDL-C (50 +/- 12 to 71 +/- 26 mg/dl; P less than 0.05). However, this effect was no longer observed at the end of three months of supplementation. Bicarbonate hemodialysis had lower baseline TG values, but carnitine supplementation did not modify plasma lipids (TG:144 +/- 87 to 158 +/- 115 mg/dl; HDL-C:50 +/- 23 to 50 +/- 19 mg/dl). Both groups had a significant increase in plasma carnitine levels after carnitine supplementation. These results suggest that bicarbonate hemodialysis may add a protective effect in hyperlipidemia by reducing requirements of carnitine supplementation. On the other hand, carnitine supplementation should be considered in patients with hyperlipidemia undergoing acetate hemodialysis. The observed difference in response between acetate and bicarbonate hemodialysis may be due to enhanced formation of acetyl-CoA and fatty acid synthesis during acetate hemodialysis.

Increased androgen binding capacity in sebaceous glands in scalp of male-pattern baldness

Sebaceous glands were isolated by manual dissection under a microscope from surgical specimens of scalp skin with male pattern baldness and skin specimens of hairy and bald scalp obtained at autopsy. The 800 X g pellet (nuclear fraction) and the 164,000 X g supernatant fraction (cytosol) of homogenates of the sebaceous glands were used for measurements of androgen binding characteristics, using dextran-coated charcoal and sucrose gradient methods. Scatchard plots showed high affinity binding for [3H]dihydrotestosterone (DHT) and [3H]methyltrienolone (R1881). Nuclei prepared from bald scalp contained greater total androgen binding capacity than nuclei of hairy scalp, although Kd values of type I binding were similar (0.68 vs 0.56 nM, respectively). On sucrose gradient, the binding protein from cytosol was found in the 7 to 8S density range. Androgen binding by cytosol of sebaceous glands of hairy scalp had Kd of 1.89 +/- .79 and 2.05 +/- .56 nM for DHT and R1881, respectively, and Bmax of 18.7 +/- 4.4 and 20.0 +/- 4.6 fmol/mg protein for DHT and R1881, respectively. Cytosol from sebaceous glands of bald scalp had Kd values approximately half those of hairy scalp, and Bmax values 50%-100% higher. The bound 3H labeled DHT and R1881 could be partially displaced by testosterone (40-50%), moxestrol (28-32%), promegestone (19-26%), and delta 4-androstenedione (6-12%), but not by dehydroepiandrosterone. These data demonstrate the presence of specific androgen binding protein in sebaceous glands, and that sebaceous glands of bald scalp have greater binding affinity and capacity for androgens than those in hairy scalp. This difference may explain the greater androgenic response in androgenic alopecia.

Interaction of rabbit lipoproteins and red blood cells with liposomes of egg yolk phospholipids

After intravenous injection of liposomes prepared from egg yolk phospholipids into rabbits, the phospholipids were readily assimilated by the lipoproteins, and there were increases in the circulating levels of cholesterol and phospholipids. The increases in cholesterol level were mainly due to increases of free cholesterol. Gradient ultracentrifugation showed that the lipoproteins decreased in density, and gel filtration chromatography showed that they increased in particle size. Upon electrophoresis, they exhibited slower mobility. Liposomes recovered from rabbits 3 hr after the injection contained free cholesterol, apolipoproteins A-I, E and traces of C. The apolipoprotein may target the liposomes for uptake by hepatocytes. Incubation of the liposomes with rabbit red blood cell membranes in vitro caused a decrease in cholesterol content of the membranes. However, the cholesterol/phosphate ratio in red blood cells isolated from the rabbits after the injection of liposomes did not change significantly, suggesting rapid replenishment of red blood cell cholesterol in vivo, possibly by equilibration with lipoprotein cholesterol or tissue cholesterol. These results suggest that the injection of phospholipid liposomes may have an antiatherogenic effect by the removal of tissue cholesterol and enhancing hepatic disposal of cholesterol through the reverse cholesterol transport mechanism.

delta 5-3 beta-hydroxysteroid dehydrogenase activity in sebaceous glands of scalp in male-pattern baldness

Sebaceous glands were isolated by manual dissection using a stereomicroscope from skin specimens of bald scalp of men with male-pattern baldness undergoing hair transplant or scalp reduction surgery and also from specimens taken from hairy and bald areas of scalp at autopsy of adult male victims of accidental death within 3 h post mortem. Homogenates of the isolated glands exhibited activities of delta 5-3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 beta-hydroxysteroid dehydrogenase, and testosterone 5 alpha-reductase by the conversion of [3H]dehydroepiandrosterone (DHA) to 3H-delta 4-androstenedione (AD), [3H]testosterone, and [3H]dihydrotestosterone. Homogenates of glands from bald (B) scalp had greater 3 beta HSD activity than homogenates of glands from hairy (H) scalp. After differential centrifugation, 3 beta HSD activity was found mainly in the microsomal and 105,000 X g supernatant fractions. Specific activity of the enzyme based on protein mass was highest in the microsomal fraction; however, the total 3 beta HSD activity in the 105,000 X g supernatent of B glands was significantly (p less than .01) greater than that of H glands. 3 beta HSD activity in sebaceous glands isolated from autopsy specimens did not differ from that of glands isolated from surgical specimens in apparent Km (0.13-0.14 microM), pH optima (8.0), or coenzyme requirement for NAD. Since substantial 3 beta HSD activity was present in the cytosol, and cytosol of B glands showed increased 3 beta HSD activity, the increased conversion of DHA to AD may be a critical step for androgenic action and may be responsible for excessive androgenicity in male-pattern baldness.

Oestrogen and progesterone receptors in lentigo maligna

We have measured oestrogen and progesterone binding in specimens of histopathologically confirmed lentigo maligna (LM) lesions excised from five elderly white men, using a dextran-coated charcoal method. Oestrogen binding was observed in four of the five specimens, and progesterone binding in all five. Marginal normal skin showed only non-specific binding for oestrogen and progesterone. The presence of steroid hormone receptors in LM suggests the possibility that hormone responsiveness may be relevant in the transformation of a lentigo maligna into malignant melanoma.

Lipid and lipoprotein levels in undialyzed patients with chronic renal failure

Lipid and lipoprotein levels were measured in undialyzed uremic men and compared with levels of healthy control subjects. The patients had lower high-density lipoprotein (HDL) cholesterol (mean +/- SD, 46.3 +/- 14.8 vs 54.1 +/- 18.2 mg/dl) and increased serum triglycerides (197 +/- 151 vs 142 +/- 87.7 mg/dl). When compared with patients maintained on dialysis, the undialyzed patients had higher HDL cholesterol (46.3 +/- 14.8 vs 30.3 +/- 13.3 mg/dl), serum cholesterol (226 +/- 81 vs 151 +/- 42 mg/dl), and triglycerides (197 +/- 151 vs 146 +/- 105 mg/dl). The low-density lipoprotein (LDL): high-density lipoprotein cholesterol ratios were 3.78, 3.24, and 2.84 in the dialyzed, undialyzed, and control groups, respectively. Lecithin: cholesterol acyl transferase activity of undialyzed patients was similar to controls when measured by an endogenous substrate assay (148 +/- 112 vs 112 +/- 28 nmol/ml/hr), but were significantly lower when assayed using exogenous substrate (73.3 +/- 25.6 vs 112.8 +/- 7 nmol/ml/hr). The rate of cholesterol transfer (RCT) from HDL to very low density lipoprotein and LDL was in the following order: dialyzed patients (1.85 +/- 1.29 mg/dl/hr) less than undialyzed patients (2.41 +/- 1.57 mg/dl/hr) less than control subjects (4.83 +/- 3.13 mg/dl/hr). Within the undialyzed patient group, black patients had lower serum cholesterol and triglycerides and higher HDL and HDL3 cholesterol than white patients. Apoprotein A-I levels were higher and apoprotein B levels were lower in the black patients. There was a strong correlation (r = 0.9501) between apoprotein A-I and HDL levels in the black patients, but not in the white patients (r = -0.148).(ABSTRACT TRUNCATED AT 250 WORDS)

High-density lipoprotein and glycosylated hemoglobin in nondiabetic individuals

We investigated associations of high-density-lipoprotein (HDL) cholesterol, apolipoprotein A-I, and triglyceride levels with hemoglobin A1 (HbA1) and insulin levels in nondiabetic subjects (137 women and 111 men). In women, HDL cholesterol, apolipoprotein A-I, and log-triglyceride values were significantly correlated with those of HbA1 and log-fasting insulin. These univariate associations persisted when age and Quetelet's index were included as covariates in multiple regression analyses. Conversely, univariate associations of HDL cholesterol and log-triglyceride levels with Quetelet's index were diminished by the addition of insulin values to multivariate models. Insulin levels and Quetelet's index were highly correlated. Although there were weaker associations in men, apolipoprotein A-I and HbA1 values were inversely related. These data suggest that HDL cholesterol and apolipoprotein A-I levels are closely linked to glucose metabolism in nondiabetic individuals.

A fluorometric method for the determination of triglycerides in nanomolar quantities

A fluorometric assay for triglycerides in nanomole quantities is described. Glycerol is liberated from triglycerides with lipase from Chromobacter viscosum, then converted by glycerol kinase to glycerol-3-phosphate, which is oxidized by glycerol-3-phosphate oxidase, producing H2O2. The H2O2 ultimately forms a peroxidase-catalyzed fluorogen with p-hydroxyphenylacetic acid. The excitation and emission wavelengths of the fluorogen are 325 and 415 nm, respectively. The assay is linear in the range 0.05-35 nmol of triglycerides using triolein as standard.

Lack of a persistent reduction in serum lipid and apoprotein levels in insulin-dependent diabetic patients receiving intensified insulin treatment

Type I insulin-dependent diabetic patients have an increased risk of atherosclerotic vascular disease that may be determined in part by their tendency to develop circulating lipid and lipoprotein abnormalities. The occurrence of such findings in asymptomatic ambulant Type I patients with mild or moderate hyperglycemia might suggest that conventional methods of insulin treatment are as inefficient at normalizing lipid abnormalities as they are in achieving euglycemia. It would then be important to ascertain whether intensive methods of insulin treatment effectively normalized lipid levels. Ten insulin-dependent young adult diabetic patients were studied on a conventional insulin treatment regimen and then at two-monthly intervals for a six-month period during which they were managed by three different intensified insulin treatment regimens. Plasma glucose levels improved substantially (p less than 0.001) after two months of intensified therapy (106 +/- 4 mg/dl) and did not change significantly thereafter for the remaining four months of intensified insulin treatment. Apart from a short-lived decrease in total-, LDL- and HDL-cholesterol after two months of intensified treatment (baseline total triglyceride 116 +/- 13 mg/dl, total cholesterol 174 +/- 16 mg/dl, HDL-cholesterol 46 +/- 3 mg/dl). There were no persistent changes in serum lipids, lipoprotein cholesterol or in levels of their major apoproteins A-I, A-II and B. These findings support the contention that, despite moderate hyperglycemia, conventional insulin treatment may be adequate to maintain normal lipid levels. In such circumstances achievement of euglycemia by intensified insulin therapy leads to little change in circulating lipid and lipoprotein values.

delta 5-3 beta-Hydroxysteroid dehydrogenase delta 4-5-isomerase activity and metabolism of dehydroepiandrosterone in rat preputial gland

After intracardial injection of [1,2-3H]dehydroepiandrosterone ([3H]DHA) into female rats, [3H]DHA was found to accumulate and was metabolized in the preputial gland, but not in the diaphragm. The identified metabolites of [3H]DHA in the preputial gland were delta 4-androstenedione-3 alpha, 17 beta-diol. Cells were isolated from the preputial gland after treatment with trypsin and collagenase III, and centrifugation in Ficoll gradients. Activity of the enzyme complex delta 5-3 beta-hydroxysteroid dehydrogenase delta 4-5-isomerase (3 beta-HSD) responsible for transforming DHA into delta 4-androstenedione was found mainly in the 105,000 g pellet (microsomal fraction) of homogenates of the isolated cells. It used preferentially NAD over NADP as a coenzyme, with a pH optimum at 8.5. The apparent Km for DHA was 5.5 X 10(-5) M, and the Vmax was 1.72 nmol/min/mg microsomal protein. These findings indicate that DHA is preferentially taken up by the preputial gland where it undergoes metabolism to form more potent androgens, and suggest that DHA may have important androgenic influence on the preputial gland.

Persistence of serum lipid abnormalities in children with idiopathic nephrotic syndrome

We investigated the severity and duration of hyperlipidemia in 59 nephrotic children during relapse and remission. Serum total cholesterol and triglyceride values were greater than or equal to 95th percentile for age and sex in all patients with minimal change nephrotic syndrome in relapse and in patients with non-MCNS and persistent proteinuria. Most of these patients also had a significant elevation of low- and very-low-density lipoproteins. A significant number of children with MCNS during prolonged remission had elevated serum concentrations of total cholesterol (46%), triglycerides (42%), LDL (29%), and VLDL (40%). Persistence and severity of lipid changes correlated well with duration of disease and frequency of relapses. Significantly decreased HDL and HDL/LDL were found in patients with non-MCNS and persistent proteinuria. Our results suggest that nephrotic children may have prolonged periods of hyperlipidemia even after clinical remission. In addition, some of these children with significantly decreased HDL/LDL may be at increased risk of developing premature atherosclerosis.

Transformation of dehydroepiandrosterone into dihydrotestosterone by isolated cells from rat preputial gland

After the rat preputial gland was treated with collagenase and trypsin, five bands of cells were isolated by centrifugation in Ficoll gradients. Homogenates of the heavier cells (Bands IV and V) which contained less lipids, were more active than the homogenates of the lighter cells (Bands I, II and III) in transforming [1,2-3H]-dehydroepiandrosterone ([1,2-3H]-DHA) into [3H]-androstenedione and [3H]-testosterone and the latter into [3H]-dihydrotestosterone (DHT). In the presence of NAD, NADH and NADPH-generating system, [1,2-3H]-DHA was transformed into [3H]-DHT in 50-60% yield by homogenates of cells in Bands IV and V. DHT levels in the preputial gland were measured by radioimmunoassay. The levels in female rats reduced by 77% from 3.14 +/- 0.27 to 0.72 +/- 0.10 pg/mg tissue after adrenalectomy, and by 45% to 1.71 +/- 0.10 pg/mg tissue after ovariectomy. In male rats, the level reduced by 15% from 4.58 +/- 0.55 to 3.88 +/- 0.62 pg/mg tissue after adrenalectomy and by 40% to 2.74 +/- 0.21 pg/mg tissue after orchidectomy. These results demonstrated the transformation of DHA into DHT in the preputial gland of the rat, and that the adrenal is an important source of precursor steroid (DHA) for DHT formation in the preputial gland.

Cord blood serum in newborns of diabetic mothers

Serum cholesterol, triglycerides and lipoprotein cholesterol were measured in cord bloods from 117 newborns. Group I consisted of 39 infants of diabetic mothers and Group II (control) consisted of 78 newborns of non-diabetic mothers. The most significant difference in serum lipids between the two groups was the higher levels of LDL cholesterol and lower levels of HDL cholesterol in the newborns of diabetic mothers. Cord blood serum cholesterol was slightly, but not significantly, higher in children born of diabetic mothers. Serum triglycerides were also not significantly different between the groups. While it remains to be established whether elevated levels of LDL cholesterol and decreased levels of HDL cholesterol at birth in these infants represent a transient phenomenon, this study suggests that newborns of diabetic mothers may be predisposed early in life to LDL hypercholesterolemia and thus may be at a greater risk of developing coronary heart disease later in life.

Serum cholesterol binding reserve and high density lipoprotein cholesterol in patients on maintenance hemodialysis

Serum cholesterol binding reserve (SCBR, the capacity of the serum to solubilize additional cholesterol), high density lipoprotein cholesterol (HDL . Ch) and serum levels of cholesterol and triglycerides were measured in 53 chronically uremic patients (40 men and 13 women) undergoing maintenance hemodialysis. The values were compared with those of controls (149 men and 28 women) matched for serum lipid levels. Hypertriglyceridemia and decreased HDL . Ch were observed among the patients, confirming previous reports. SCBR values of the patients were not significantly different from those of controls except in a small subgroup of uremic diabeties, whose SCBR values were markedly decreased. There was a positive correlation between SCBR and the duration for which the patients had been maintained by hemodialysis. The results suggest that patients with higher SCBR values have a better prospect for surviving long duration of hemodialysis.

Serum-cholesterol-binding reserve in patients with the nephrotic syndrome

Hyperlipidemia and premature atherosclerosis are known metabolic complications in patients with the nephrotic syndrome. In this study, we have measured serum levels of cholesterol, triglycerides and serum-cholesterol-binding reserve (SCBR) in 22 patients (14 men, 8 women) with the nephrotic syndrome and in 21 hyperlipidemic men who served as control subjects. Serum cholesterol levels were higher (p less than 0.005) in patients when compared to those of controls while triglyceride levels did not differ significantly between the groups. SCBR levels were lower (p less than 0.001) in the nephrotic subjects. The abnormally low SCBR values may be an important risk factor for atheroclerosis as suggested by previous studies in patients surviving premature myocardial infarction.

Effects of steroids on serum lipids and serum cholesterol binding reserve

Serum cholesterol binding reserve (SCBR) denotes the capacity of serum to solubilize additional cholesterol. It as been shown previously that a decrease of the SCBR in the presence of elevated cholesterol and/or triglyceride levels is associated with the development of coronary artery disease in man. This is a preliminary report of the effect on serum lipids and SCBR by alteration of the sex steroid environment in women. The hormonal changes associated with pregnancy appear to elevate cholesterol, triglycerides, and SCBR, SCBR being elevated to the greatest extent. No differences were observed in SCBR and serum lipids in a short-term study of premenopausal women when values prior to castration are compared with values after castration during administration of conjugated equine estrogens. In women observed over a period of over 20 weeks, who were using a combination oral contraceptive pill with 1 mg. of norethindrone and 50 or 80 mcg. of mestranol, there was a significant elevation of triglycerides, some decrease of cholesterol, and no change in the SCBR. The possible significance of these findings in relation to the risk of coronary heart disease deserves further investigation.

Decreased serum cholesterol-binding reserve in diabetes mellitus

Serum cholesterol-binding reserve (SCBR), the capacity of a serum sample to solubilize additional cholesterol in excess of its cholesterol content, was measured in 43 white male patients with maturity-onset diabetes in the age range of 35--59 years who were under treatment with insulin. The values were compared with those of 194 nondiabetic controls of the same race, sex, and age range. The mean +/- S.D. of SCBR of patients (71.9 +/- 29.3 mg./dl.) was lower than that of controls (88.9 +/- 30.9 mg./dl.) (p less than 0.001). Age in the range of 35 to 59 years had no correlation with SCBR in either patients or controls. SCBR was positively correlated with serum levels of cholesterol (SC) and triglycerides (TG) in both patients and controls. After adjustment for SC and TG, the difference in SCBR between patients and controls persisted (p less than 0.001). In 15 of 20 (75 per cent) patient-control pairs matched for SC and TG to within 5 per cent, the patient had lower SCBR (paired t-test, p less than 0.002). In 16 patients without elevation of serum lipid levels (SC below 250 and TG below 150 mg./dl.), the mean +/- S.D. of SCBR (59.1 +/- 17.7 mg./dl.) was lower than that of 49 controls having serum lipids in the same range (77.4 +/- 31.7 mg./dl.) (p less than 0.03). These results indicate an association of decreased SCBR with diabetes and are consistent with the hypothesis that low SCBR is associated with accelerated atherosclerosis and enhanced risk for coronary heart disease.

Inhibition of cholesterol esterification in rabbit aorta by prostaglandin E2

Cholesterol esterification in the arterial wall was investigated with cell-free preparations of intima-media from control rabbits and rabbits rendered atherosclerotic by feeding a diet containing 1% cholesterol. In the presence of 2 mM ATP and 0.1 mM CoA, the major activity for esterification of [4-14C] cholesterol added in vitro was found in the 12,000 g and 105,000 g pellets. In control animals, the activity in the latter pellet was twice that in the former. After cholesterol-feeding for 6 months, the activity increased 5-fold in the 105,000 g pellet and 2-fold in the 12,000 g pellet of the atherosclerotic intima-media. Prostaglandin E2 (PGE2) in concentrations between 2 and 12 X 10(-7) M exhibited a dose-dependent inhibition of the esterifying activity in both particulate preparations. The inhibition was 97% at PGE2 concentrations greater than 1.2 X 10(-6) M in preparations from control animals. Inhibition by PGE2 in preparations from atherosclerotic rabbits was also observed. These results suggest a possible regulatory role of PGE2 in cholesterol esterification in the arterial wall.

Estrogen-binding protein from rat preputial gland: purification and characterization

Cytosol from the rat preputial gland has been shown to contain a protein which binds both estrone and estradiol. The protein, after a 26-fold purification from the cytosol of female Sprague-Dawley rats, migrated as one band during electrophoresis in sodium dodecyl sulfate on acrylamide gel. The electrophoretic mobility indicated a molecular weight of 15,000. The association constant for estrone as determined by equilibrium dialysis was 1.2 X 10(7) M-1, while that for 17beta-estradiol was 3.3 X 10(6) M-1. Progesterone, cortisol, testosterone, or diethylstilbestrol did not bind to the purified protein, whereas 17alpha-estradiol or estriol bound only slightly. In the presence of retinoic acid, but not retinol, the binding of estrone was reduced. Optimum binding for estrone was at pH 6.5 to 8.5.

Prostaglandin E2 biosynthesis: changes in rabbit aorta and skin during experimental atherogenesis

The transformation of [1-14C]arachidonic acid into [14C]prostaglandin E2(PGE2) by rabbit aorta and skin was demonstrated by cell-free preparations, and the PGE2 synthetase activity was located mainly in the microsomal fraction (105,000 g pellet) of both tissues. Rabbits fed an atherogenic diet (Purina rabbit chow plus 1% cholesterol and 2% cottonseed oil) developed atheroma in the aortas and skin lesions resembling xanthoma in 6 to 7 months. At the end of this period, increases in the conversion of [1-14C]-arachidonic acid into [14C]PGE2 were observed in microsomal preparations of the intima-media of the aortas (2.5-fold of control) and normal-appearing skin (3.0-fold of control) of the experimental animal. Microsomal preparations of skin lesions particularly had greater ability to form PGE2 (7-fold of control).

Decreased serum cholesterol-binding reserve in premature myocardial infarction

Incubation of human serum with crystalline cholesterol which had been pulverised by sonication resulted in a measurable uptake of cholesterol by the serum. This uptake was designated "serum cholesterol-binding reserve" (S.C.B.R.). Among more than 200 men and women examined, S.C.B.R. values varied from less than 10 to over 200 mg/dl, while the values from repeated determinations on two individuals over several months varied within 24 mg/dl. S.C.B.R. could be attributed to two serum-lipoprotein subfractions--S.F.V. separated from very-low-density lipoprotein and S.F.H. from high-density lipoprotein, by gel filtration. Without further purification, S.F.V. solubilised 4-5 mg and S.F.H. solubilised 0-36 mg of additional cholesterol/mg of protein, while the remaining bulk of the lipoproteins lacked this property. It is proposed that S.F.V. and S.F.H. have physiological roles in retarding atherogenesis by removing cholesterol from the arterial intima and carrying it back to the circulating serum. Accordingly, individuals who have low S.C.B.R. values, being deficient in S.F.V. and S.F.H., are at higher risk for the development of atherosclerosis and coronary heart-disease. This hypothesis was tested by comparing S.C.B.R. values of patients with premature myocardial infarction with values of controls. The results indicated a trend of increasing S.C.B.R. values with increasing levels of serum cholesterol and triglycerides among the controls, but this trend was virtually lost among the patients. The S.C.B.R. values also were lower among patients than controls, and the difference was statistically significant between patients and controls with serum-cholesterol above 250 mg/dl or fasting serum-triglycerides above 160 mg/dl. These results are consistent with the proposed hypothesis.

Cyclic AMP and psoriasis

Evidence that an adenyl cyclase system is present in all mammalian epidermis is reviewed. This adenyl cyclase is stimulated by at least two separate types of chemicals: catecholamines, which act at a beta-adrenergic receptor site, and prostaglandins of the E series, which act at a separate site. In the psoriatic lesion, the response to these stimulators, especially to the catecholamines, is reduced. Despite this lack of response to external agents which elevate cyclic AMP, the concentration of cyclic AMP within the epidermis of the psoriatic lesion is no lower than in noninvolved skin. How cyclic nucleotides act to control cell proliferation and cell differentiation remains unclear.

Further studies on adenyl cyclase in psoriasis

Slices of human skin obtained with a keratome were pre-incubated with [3H]adenine to label the ATP pool from which cyclic AMP was subsequently formed. The accumulation of radioactive cyclic AMP was measured as an index of adenyl cyclase activity. The data showed that both the ability to incorporate [3H] into ATP and adenyl cyclase activity were significantly lower in psoriatic plaques than in uninvolved skin of the psoriatic patients, or in normal skin of control subjects. The response of adenyl cyclase to the stimulation of 3.3 muM adrenaline was less than five fold in psoriatic plaques as compared to twelve to thirty-two fold in the uninvolved skin. The response to the stimulation of prostaglandin E2 (5 mug/ml) showed no significant difference between the plaque and normal skin. The adenyl cyclase activity in uninvolved skin of psoriatic patients appeared normal. Propranolol (10 muM) blocked the stimulatory effect of adrenaline but not that of PGE2 in normal skin. These results suggest that the adenyl cyclase system of the skin has different regulatory sites for adrenaline and PGE2 and that the enzyme is defective in the epidermis of the psoriatic plaque, especially at the adrenaline regulatory site.

Effects of prostaglandin E 2 on rat skin: inhibition of sterol ester biosynthesis and clearing of scaly lesions in essential fatty acid deficiency

Severe scaly lesions in the skin, especially in the feet and tail, of the rat were induced by feeding a diet deficient in essential fatty acids (EFA). Analysis of the fatty acids in skin lipids of these EFA-deficient rats showed a marked increase of monoenoic acids (16:1 and 18:1) and eicosatrienoic acid (20:3), with concomitant decreases of dienoic acid (18:2) and tetraenoic acid (20:4). Topical application of prostaglandin E(2) (PGE(2)) to the scaly lesions resulted in clearance of the lesions, but did not significantly alter the composition of fatty acids in the skin. Intraperitoneal injection of PGE(2) had no observable effect on the skin lesions. Furthermore, incubation of skin specimens from the EFA-deficient rats with (14)C-labeled glucose showed a 4-5-fold increase of incorporation of glucose carbon into lipid fractions, particularly the sterol esters, and a 3-4-fold increase in pentose cycle activity. Addition of PGE(2) to the incubation mixture resulted in approximately 70% inhibition of sterol ester biosynthesis by skin of the EFA-deficient rats. These results suggest that the effects of PGE(2) in clearing the scales may be associated with its inhibitory effect on abnormal sterol esterification in the skin of the EFA-deficient rats.

Inhibition of lipid synthesis by clofibrate: comparative study of human skin, rat skin, and rat liver in vitro

The effects of clofibrate (ethyl p-chlorophenoxyisobutyrate) on lipid synthesis by human skin were studied in vitro. The drug was found to inhibit lipid synthesis from [1-(14)C]acetate or [U-(14)C]glucose. While the synthesis of all classes of lipids was suppressed, inhibition of sterol synthesis was more pronounced than that of fatty acids and glycerides. By comparison, sodium p-chlorophenoxyisobutyrate was less effective as an inhibitor. The addition of glucose to the incubation medium enhanced lipid synthesis from both [1-(14)C]acetate and [U-(14)C]glucose. The inhibitory effect of clofibrate could be partially reversed by increasing the glucose concentration in the incubation medium. Rat skin and rat liver were studied similarly, using [1-(14)C]-acetate as a tracer for lipid synthesis, and the inhibitory effect of clofibrate was also demonstrated. Of the three tissues studied, human skin was the most sensitive to the drug and yielded more reproducible results.