Gene therapy for rhesus monkeys heterozygous for LDL receptor deficiency by balloon catheter hepatic delivery of helper-dependent adenoviral vector.

Autosomal dominant familial hypercholesterolemia (FH) is a monogenic life-threatening disease. We tested the efficacy of low-density lipoprotein receptor (LDLR) gene therapy using helper-dependent adenoviral vector (HDAd) in a nonhuman primate model of FH, comparing intravenous injection versus intrahepatic arterial injection in the presence of balloon catheter-based hepatic venous occlusion. Rhesus monkeys heterozygous for mutant LDLR gene (LDLR+/-) developed hypercholesterolemia while on a high-cholesterol diet. We treated them with HDAd-LDLR either by intravenous delivery or by catheter-based intrahepatic artery injection. Intravenous injection of ⩽1.1 × 10(12) viral particles (vp) kg(-1) failed to have any effect on plasma cholesterol. Increasing the dose to 5 × 10(12) vp kg(-1) led to a 59% lowering of the plasma cholesterol that lasted for 30 days before it returned to pre-treatment levels by day 40. A further increase in dose to 8.4 × 10(12) vp kg(-1) resulted in severe lethal toxicity. In contrast, direct hepatic artery injection following catheter-based hepatic venous occlusion enabled the use of a reduced HDAd-LDLR dose of 1 × 10(12) vp kg(-1) that lowered plasma cholesterol within a week, and reached a nadir of 59% pre-treatment level on days 20-48 after injection. Serum alanine aminotransferase remained normal until day 48 when it went up slightly and stayed mildly elevated on day 72 before it returned to normal on day 90. In this monkey, the HDAd-LDLR-induced trough of hypocholesterolemia started trending upward on day 72 and returned to pre-treatment levels on day 120. We measured the LDL apolipoprotein B turnover rate at 10 days before, and again 79 days after, HDAd-LDLR treatment in two monkeys that exhibited a cholesterol-lowering response. HDAd-LDLR therapy increased the LDL fractional catabolic rate by 78 and 50% in the two monkeys, coincident with an increase in hepatic LDLR mRNA expression. In conclusion, HDAd-mediated LDLR gene delivery to the liver using a balloon catheter occlusion procedure is effective in reversing hypercholesterolemia in a nonhuman primate FH model; however, the unsustainability of the hypocholesterolemic response during 3-4 months of follow up and heterogeneous response to the treatment remains a challenge.

Contribution of medical colleges to tuberculosis control in India under the Revised National Tuberculosis Control Programme (RNTCP): lessons learnt & challenges ahead.

Medical college faculty, who are academicians are seldom directly involved in the implementation of national public health programmes. More than a decade ago for the first time in the global history of tuberculosis (TB) control, medical colleges of India were involved in the Revised National TB Control Programme (RNTCP) of Government of India (GOI). This report documents the unique and extraordinary course of events that led to the involvement of medical colleges in the RNTCP of GOI. It also reports the contributions made by the medical colleges to TB control in India. For more than a decade, medical colleges have been providing diagnostic services (Designated Microscopy Centres), treatment [Directly Observed Treatment (DOT) Centres] referral for treatment, recording and reporting data, carrying out advocacy for RNTCP and conducting operational research relevant to RNTCP. Medical colleges are contributing to diagnosis and treatment of human immunodeficiency virus (HIV)-TB co-infection and development of laboratory infrastructure for early diagnosis of multidrug-resistant and/or extensively drug-resistant TB (M/XDR-TB) and DOTS-Plus sites for treatment of MDR-TB cases. Overall, at a national level, medical colleges have contributed to 25 per cent of TB suspects referred for diagnosis; 23 per cent of 'new smear-positives' diagnosed; 7 per cent of DOT provision within medical college; and 86 per cent treatment success rate among new smear-positive patients. As the Programme widens its scope, future challenges include sustenance of this contribution and facilitating universal access to quality TB care; greater involvement in operational research relevant to the Programme needs; and better co-ordination mechanisms between district, state, zonal and national level to encourage their involvement.

Carbimazole induced ANCA positive vasculitis.

Anti-thyroid drugs, like carbimazole and propylthiouracil (PTU) are commonly prescribed for the treatment of hyperthyroidism. One should be aware of the side effects of antithyroid medications. Antineutrophil cytoplasmic antibody (ANCA)--associated vasculitis is a potentially life-threatening adverse effect of antithyroidmedications. We report a patient with Graves' disease who developed ANCA positive carbimazole induced vasculitis. The episode was characterized by a vasculitic skin rash associated with large joint arthritis, pyrexia and parotiditis but no renal or pulmonary involvement. He was referred to us for neurological evaluation because he had difficulty in getting up from squatting position and was suspected to have myositis. Carbimazole and methimazole have a lower incidence of reported ANCA positive side effects than PUT. To the best of our knowledge this is the first ANCA positive carbimazole induced vasculitis case reported from India.

Effect of estrogen and progesterone on the hepatic cholesterol 7-alpha-hydroxylase activity in ovariectomized baboons.

Cholesterol 7 alpha-hydroxylase activity was measured in livers from ovariectomized baboons fed a high cholesterol high saturated fat diet and maintained in four groups: untreated controls, estrogen (100 micrograms/g per week), progesterone (3 mg/kg per day) and estrogen + progesterone. Estrogen treatment alone increased hepatic 7 alpha-hydroxylase activity by 2.7-fold, whereas progesterone treatment alone did not influence hepatic 7 alpha-hydroxylase activity. The increase in 7 alpha-hydroxylase activity in estrogen + progesterone group was similar to that in the estrogen group.

Characterization of very-low-density lipoproteins isolated from baboons, and fractionated using heparin-Sepharose chromatography.

Plasma very-low-density lipoproteins (VLDL) (d less than 1.006 g/ml) were purified from baboons by repeated ultracentrifugation. The weight composition of VLDL purified from these animals was 59% triacylglycerol, 17% phospholipid, 13% cholesterol plus cholesteryl esters, and 11% protein. When purified VLDL was fractionated using heparin-Sepharose chromatography, an average of 33% of the total recovered proteins were unbound in a saline solution, and 67% (range, 31 to 92%) were bound by the column, but could be eluted with 3 M NaCl. Recoveries of starting protein and the major classes of lipids in the two fractions were 70-80%. The two fractions differed in both apolipoprotein and lipid compositions. Analysis of sodium dodecyl sulfate-treated apolipoproteins using 3-21.5% acrylamide gradient gel electrophoresis indicated that both VLDL fractions contained apolipoprotein B, but only the bound fraction possessed significant amounts of apolipoprotein E. On a weight percent basis, the apolipoprotein-E-rich (bound) VLDL fraction contained significantly more cholesterol and cholesteryl esters (P less than 0.001) and less phospholipids (P less than 0.005) compared to the apolipoprotein E-poor (unbound) VLDL. Apolipoprotein-E-poor VLDL had shorter retention times than E-rich VLDL upon gel filtration chromatography, suggesting a larger size. There was no significant correlation between plasma levels of apolipoprotein-E-poor VLDL and levels of apolipoprotein B. These results demonstrate that baboons possess VLDL which can be separated into apolipoprotein-E-poor and E-rich fractions and these fractions differ in protein and lipid composition and in size.

Differences in 27-hydroxycholesterol concentrations in plasma and liver of baboons with high and low responses to dietary cholesterol and fat.

Selective breeding has produced baboon progeny that have low or high response in plasma low-density lipoprotein (LDL) cholesterol when fed a high cholesterol and high fat (HCHF) diet. We examined differences in bile acid metabolism between low and high responding baboons by measuring the most abundant oxysterol in plasma and liver. Low responding baboons had higher concentrations of plasma and liver 27-hydroxycholesterol than high responding baboons on the HCHF diet but not on the chow diet. The increased hepatic 27-hydroxycholesterol in low responders was associated with an increase in sterol 27-hydroxylase activity as compared to high responders. These studies suggest that the hepatic sterol 27-hydroxylase is induced by dietary cholesterol and this induction is much higher in low responding baboons.

Metabolism of very low density lipoproteins in diet induced hypercholesterolemic pigtail monkeys (Macaca nemestrina).

Cholesterol-fed male pigtail monkeys were used to determine the metabolic mechanism of dietary hypercholesterolemia. Cholesterol feeding (200--400 mg/day) in monkeys produced a moderate hypercholesterolemia, which progressed with time and after 15 months the plasma cholesterol levels were raised 8-fold. The initial rise in plasma cholesterol was due to an increase in low density lipoproteins (LDL), but later the increases in intermediate (IDL) and very low (VLDL) density lipoproteins were mainly responsible for the rise in plasma cholesterol. To determine the metabolic mechanism, animals, both before and after cholesterol feeding, were co-injected with 131I-labelled VLDL from normal and 125I-labelled VLDL from cholesterol-fed donors. The fractional catabolic rate of autologous VLDL apolipoprotein B, which decayed biphasically, depended upon the dietary status of the recipient animal. The decrease in fractional catabolic rate was due to more VLDL apolipoprotein B being metabolized by the slower second phase. Normal VLDL apolipoprotein B in cholesterol-fed animals was catabolized by the slower second phase to a greater proportion than that in normal animals, where it was mainly transferred to LDL.

Catabolism of very low density lipoproteins in the rabbit. Effect of changing composition and pool size.

To determine the metabolic mechanism of hypercholesterolemia in rabbits produced by feeding cholesterol-rich diets, control and hypercholesterolemic rabbits were injected with I-labelled very low density lipoproteins (VLDL, d 1.006 g/ml) from control and/or hypercholesterolemic donors. Apolipoprotein B in VLDL decayed biphasically. The first phase occurred much more rapid than the second. 95% of the VLDL apolipoprotein B was catabolized via the first phase (t1/2 = 0.55 +/- 0.19 h) in normal rabbit with the immediate appearance of this radioactivity in intermediate density lipoproteins (IDL, d 1.006-1.025 g/ml) and low density lipoproteins (LDL, d 1.025-1.063 g/ml). The apolipoproteins C and E at the same time were transferred to high density lipoproteins where they decayed biphasically. The apolipoprotein B from hypercholesterolemic VLDL in the normal recipient disappeared at a similar rate as from normal VLDL via phase I; however, it was incompletely converted to IDL and LDL. Apolipoprotein B from normal VLDL in cholesterol-fed rabbits disappeared at a normal rate via phase I, but only 82% was catabolized by this phase. Hypercholesterolemic VLDL injected into the hypercholesterolemic recipient was less rapidly catabolized via phase I (T1/2 = 2.5 +/- 0.89 H) and only a small fraction was converted to IDL and LDL.

High density lipoprotein metabolism in normolipidemic and cholesterol-fed rabbits.

New Zealand white rabbits were used to determine the compositional and metabolic changes induced in high density lipoproteins (HDL, rho = 1.063--1.21 g/ml) in response to cholesterol feeding. There was no change in total HDL cholesterol in plasma due to cholesterol feeding (12 weeks), but the triglyceride level was decreased to 29% of pretreatment values. Total protein content of HDL was decreased in response to cholesterol feeding, resulting in a significant increase in the cholesterol/protein ratio. There was a decrease in some isomer of the major apolipoproteins (A-I2) of HDL. The decay of radioactivity in HDL or its apolipoproteins was biphasic in both normolipidemic and hypercholesterolemic rabbits. The first phase was much more rapid than the second. The decay rates for the radioactivity in HDL depended upon the dietary status of the recipient animal.

Characterization of an unusual lipoprotein similar to human lipoprotein a isolated from the baboon, Papio sp.

An unusual lipoprotein was detected and purified from the blood of some members of a large colony of baboons, Papio sp. This lipoprotein was found to be similar to human lipoprotein a in all respects and is therefore termed lipoprotein a. Baboon lipoprotein a had a density of 1.052 g/ml and was located between low- and high-density lipoproteins in a density gradient ultracentrifugation. However, despite its greater density, baboon lipoprotein a was larger than low-density lipoprotein, based on gradient gel electrophoresis and gel filtration. The lipoprotein contained a very large apolipoprotein (apolipoprotein-lipoprotein a) which was found to consist of an apolipoprotein B linked to another protein called apolipoprotein a by a disulfide bridge(s). In all these characteristics, baboon lipoprotein a was similar to human lipoprotein a.

Effect of naturally reduced ovarian function on plasma lipoprotein and 27-hydroxycholesterol levels in baboons (Papio sp.).

Female baboons over 15 years of age develop irregular menstrual cycles, an indication of declining ovarian function similar to that occurring in perimenopausal women. To determine the effect of declining ovarian function on plasma lipoprotein metabolism and plasma oxysterols, we measured plasma lipoprotein and 27-hydroxycholesterol levels in 86 female baboons from 15-28 years of age with regular (n = 51) and irregular (n = 35) menstrual cycles. We sampled blood and liver while they were consuming a basal diet and after consuming a high cholesterol and high fat diet for 7 weeks. On the basal diet, baboons with irregular cycles had higher VLDL + LDL/HDL cholesterol ratios (P = 0.034). After consuming the HCHF diet for 7 weeks, total plasma (P < 0.001) and VLDL + LDL (P < 0.001) cholesterol concentrations and VLDL + LDL/HDL sterol ratios (P < 0.001) increased in both cycle groups; whereas HDL cholesterol concentrations increased only in baboons with regular cycles (P = 0.009). As a result, HDL cholesterol concentrations (P = 0.006) were lower and VLDL + LDL/HDL cholesterol ratios (P = 0.002) were higher in baboons with irregular cycles on the HCHF diet. Plasma 27-hydroxycholesterol concentrations were higher in baboons with regular cycles than in those with irregular cycles on both basal (P = 0.018) and HCHF (P = 0.037) diets and were positively correlated (P < 0.001) with hepatic sterol 27-hydroxylase activities on both diets. Hepatic sterol 27-hydroxylase activities were negatively correlated with the VLDL + LDL/HDL cholesterol ratios on the HCHF diet (r = -0.342, P = 0.033). These results suggest that declining ovarian function changes the plasma lipoprotein pattern to one that is more atherogenic. Ovarian failure is also associated with decreased concentrations of plasma 27-hydroxycholesterol (the major oxysterol of plasma), and the decrease in plasma 27-hydroxycholesterol concentration was due to the decrease in hepatic sterol 27-hydroxylase activity. The effects of ovarian failure on plasma lipoprotein metabolism and plasma 27-hydroxycholesterol may be mediated by the decreased production of estrogen in perimenopausal baboons. Thus, the perimenopausal baboon is an excellent model for menopause and can be used for studies that cannot be conducted in women.

Short-term egg yolk feeding in humans. Increase in apolipoprotein B and low density lipoprotein cholesterol.

In animal studies, hypercholesterolemia induced by cholesterol feeding results in the plasma cholesterol being transported by lipoproteins of lower densities. Little information is available for humans. To determine the specific lipoprotein responses to dietary cholesterol challenge in humans, four volunteer subjects ingested a liquid formula diet containing 5000 mg of egg yolk cholesterol per day for 30 days and the changes in their lipoprotein fractions were examined. The high dietary cholesterol (above the range of normal diet) was associated with marked increases in apolipoprotein B and low density lipoprotein (LDL) cholesterol levels. An elevated cholesterol : triglyceride ratio in the LDL fraction indicated that the diet altered both LDL level and composition. High density lipoprotein cholesterol and apolipoprotein AI increased slightly. Very low and intermediate density lipoprotein cholesterol and apolipoprotein E levels did not increase during the diet. Thus, high dietary cholesterol was associated with major changes in LDL level and composition, but only minor changes in the other lipoprotein fractions and suggested only minor accumulation of remnant particles.

Exogenous estrogens attenuate dietary hypercholesterolemia and atherosclerosis in the rabbit.

The effect of exogenous estrogens upon the response to dietary cholesterol was tested in New Zealand White rabbits. Cholesterol-fed, untreated rabbits had a 10-fold increase in plasma cholesterol in 12 wk. The major increase of cholesterol occurred in very low density lipoproteins (VLDL, 43.5-fold) followed by intermediate density lipoproteins (IDL, 26-fold) and low density lipoproteins (LDL, 6-fold) with no change in high density lipoproteins (HDL). These diet induced changes were markedly attenuated in the estrogen treated animals, in whom plasma cholesterol increased only 5-fold. This increase was distributed among LDL (6-fold), IDL (7.5-fold), and VLDL (9-fold), similarly with no change in HDL. All the lipoproteins in both groups of animals were considerably enriched in cholesterol during cholesterol feeding as indicated by a high cholesterol/protein and cholesterol/triglyceride ration. However, these ratios were lower in estrogen treated animals. There were no differences in the feed consumption, body weight or cholesterol absorption between the two groups of animals. Rabbits fed a cholesterol-rich diet but not treated with estrogen had well developed lesions in all parts of the aorta with higher content of cholesterol and phospholipids as compared to those injected with estrogen, whose aortas were completely clear of visible atherosclerosis. Equivalent total hypercholesterolemia was induced in other estrogen-treated rabbits by feeding twice the cholesterol dietary content (0.2%) as in nonestrogen-treated animals. Aortic atherosclerosis was far more evident in the latter, which had higher proportions of cholesterol-rich lipoproteins of d less than 1.006 g/ml.

Metabolism of apolipoprotein B in members of a family with accelerated atherosclerosis: influence of apolipoprotein E-3/E-2 pattern.

Familial combined hyperlipidemia (FCHL) appears to be the most common, simply inherited hyperlipidemia strongly associated with coronary heart disease. In the family examined in this study, two of the siblings who met diagnostic criteria for FCHL had extensive clinical atherosclerosis before age 30, unusually premature for this form of hyperlipidemia. Lipoproteins and low-density lipoprotein (LDL) apolipoprotein (apo) B metabolism were characterized in these siblings in an attempt to gain insight into the cause of the rapid atherosclerosis in the two siblings so affected. LDL apo B production rates were very high in all three siblings (25 to 30 mg/kg/d), consistent with FCHL. beta-Very-low-density lipoprotein-beta (beta-VLDL) was present in the plasma of both siblings with accelerated atherosclerosis. The isoapolipoprotein E pattern in both of these siblings was E-3/E-2. In the third sibling, who was free of premature clinical atherosclerosis and lacked plasma beta-VLDL, the pattern was E-3/E-3. Thus, the heterozygote apo E-3/E-2 pattern may be related to the accumulation of beta-VLDL in persons with a very high apo B production rate. The abnormal accumulation of beta-VLDL may be one of the possible explanations for the rapid, premature atherosclerosis in the two siblings with FCHL in this kindred. Both male members in this kindred also had low levels of high-density lipoproteins, and thus may have had an additional risk of developing atherosclerosis due to this lipoprotein abnormality as well.

Chronic physiologic hyperinsulinemia impairs suppression of plasma free fatty acids and increases de novo lipogenesis but does not cause dyslipidemia in conscious normal rats.

Type 2 diabetes mellitus and obesity are characterized by fasting hyperinsulinemia, insulin resistance with respect to glucose metabolism, elevated plasma free fatty acid (FFA) levels, hypertriglyceridemia, and decreased high-density lipoprotein (HDL) cholesterol. An association between hyperinsulinemia and dyslipidemia has been suggested, but the causality of the relationship remains uncertain. Therefore, we infused eight 12-week-old male catheterized conscious normal rats with insulin (1 mU/min) for 7 days while maintaining euglycemia using a modification of the glucose clamp technique. Control rats (n = 8) received vehicle infusion. Baseline FFAs were 1.07+/-0.13 mmol/L, decreased to 0.57+/-0.10 (P < .05) upon initiation of the insulin infusion, and gradually increased to 0.95+/-0.12 by day 7 (P = NS vbaseline). On day 7 after a 6-hour fast, plasma insulin, glucose, and FFA levels in control and chronically hyperinsulinemic rats were 32+/-5 versus 116+/-21 mU/L (P < .005), 122+/-4 versus 129+/-8 mg/dL (P = NS), and 1.13+/-0.18 versus 0.95+/-0.12 mmol/L (P = NS); total plasma triglyceride and cholesterol levels were 78+/-7 versus 66+/-9 mg/dL (P = NS) and 50+/-3 versus 47+/-2 mg/dL (P = NS), respectively. Very-low-density lipoprotein (VLDL) + intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL), and HDL2 and HDL3 subfractions of plasma triglyceride and cholesterol were similar in control and hyperinsulinemic rats. Plasma FFA correlated positively with total (r = .61, P < .005) triglycerides. On day 7 after an 8-hour fast, hyperinsulinemic-euglycemic clamps with 3-3H-glucose infusion were performed in all rats. Chronically hyperinsulinemic rats showed peripheral insulin resistance (glucose uptake, 15.8+/-0.8 v 19.3+/-1.4 mg/kg x min, P < .02) but normal suppression of hepatic glucose production (HGP) compared with control rats (4.3+/-1.0 v 5.6+/-1.4 mg/kg x min, P = NS). De novo tissue lipogenesis (3-3H-glucose incorporation into lipids) was increased in chronically hyperinsulinemic versus control rats (0.90+/-0.10 v 0.44+/-0.08 mg/kg x min, P < .005). In conclusion, chronic physiologic hyperinsulinemia (1) causes insulin resistance with regard to the suppression of plasma FFA levels and increases lipogenesis; (2) induces peripheral but not hepatic insulin resistance with respect to glucose metabolism; and (3) does not cause an elevation in VLDL-triglyceride or a reduction in HDL-cholesterol.

The role of cholesterol absorption and hepatic cholesterol content in high and low responses to dietary cholesterol and fat in pedigreed baboons (Papio species).

Selective breeding has produced baboon families with low and high plasma cholesterol responses to dietary cholesterol and fat. We used 12 high- and 12 low-responding (mainly in low-density lipoprotein [LDL] cholesterol) pedigreed baboons to determine whether cholesterol absorption and hepatic cholesterol concentration are associated with these responses. We measured cholesterol absorption first on the chow diet, which was low in cholesterol and fat, and after 3 and 13 weeks on the challenge diets, which contained 0.45 mg cholesterol/kcal and 40% of calories as either coconut oil or corn oil. Plasma, lipoprotein, and hepatic cholesterol concentrations were measured 1 week after cholesterol absorption measurements. High-responding baboons had higher percentage cholesterol absorption than low-responding baboons on both chow and challenge diets, regardless of the type of dietary fat. Both high and low responders had higher percentage cholesterol absorption with corn oil than with coconut oil. High responders also had higher hepatic cholesterol concentrations than low responders on chow and after consuming the challenge diets for 4 weeks. After consuming the challenge diets for 14 weeks, low responders fed coconut oil had hepatic cholesterol levels equal to those of high responders, while low responders fed corn oil continued to have low hepatic cholesterol levels. Thus, percentage cholesterol absorption is consistently higher in high-responding baboons regardless of diet, but hepatic cholesterol concentration varies with duration of challenge and type of fat. The results suggest that both cholesterol absorption and hepatic cholesterol concentration regulate cholesterolemic responses to diet, but by different mechanisms.

Metabolic regulation of plasma apolipoprotein E by estrogen and progesterone in the baboon (Papio sp).

Apolipoprotein (apo) E plays an important role in the metabolism of lipoproteins. To determine the effects of estrogen and progesterone on plasma levels and metabolism of apo E, we used 12 ovariectomized baboons fed a cholesterol- and fat-enriched diet. These baboons were divided into four groups and treated with estrogen, progesterone, estrogen + progesterone, and a placebo control. After 10 months, although the lipid levels were not different among the treatment groups, low-density lipoprotein (LDL)/high-density lipoprotein (HDL) ratios in the estrogen + progesterone group were significantly lower than those in the control and progesterone groups. Estrogen alone or in combination with progesterone decreased plasma apo E levels significantly compared with those in the control group. Plasma apo E levels in the progesterone group were similar to those in the control group. In all groups, most (greater than 60%) of the apo E was present in HDL. HDL apo E concentrations in the estrogen and estrogen + progesterone groups were significantly lower than those in the control and progesterone groups. To determine the metabolic mechanisms of these changes in apo E levels, turnover studies were conducted by injection of iodinated apo E-labeled very-low-density lipoprotein (VLDL) and HDL. Residence times were calculated using multicompartment modeling. Progesterone alone and in combination with estrogen decreased residence times of apo E injected in both HDL and VLDL compared with estrogen alone and control groups. Progesterone alone also increased the apo E production rate compared with other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on the metabolic mechanism of reduced high density lipoproteins during anabolic steroid therapy.

To explore the mechanism whereby stanozolol, a 17 alpha-methyl androgenic anabolic steroid, depresses high density lipoproteins (HDL), 6 subjects, aged 46-71 yr (4 postmenopausal women and 2 men), underwent paired studies of 125I-HDL turnover (including HDL2 and HDL3 and Apo A-I and A-II) and postheparin plasma (PHP) lipolytic activity (hepatic triglyceride lipase, HTGL, and lipoprotein lipase LPL) before and during treatment with stanozolol, 6 mg/day. While total cholesterol and triglyceride levels did not change during stanozolol, HDL-cholesterol decreased from 59 +/- 18 mg/dl (x +/- SD) to 29 +/- 7 mg/dl (p less than 0.01) and low density lipoprotein (LDL)-cholesterol increased from 160 +/- 36 mg/dl to 181 +/- 42 mg/dl (p less than 0.02). PHP-HTGL increased from 111 +/- 47 nmole/min/ml to 369 +/- 202 nmole/min/ml (p less than 0.04), while PHP-LPL did not change. At baseline the residence time of HDL2 (4.00 +/- 1.04 day) was shorter than that of HDL3 (6.79 +/- 1.00 day) (p less than 0.001). Residence times of both declined on stanozolol, to 3.25 +/- 0.83 day and 4.00 +/- 0.29 day, respectively (0.1 less than p less than 0.2); however, only the reduction in residence time of HDL3 was statistically significant (p less than 0.001). At baseline the residence time of apo A-I (4.93 +/- 1.32 day) was shorter than that of A-II (6.85 +/- 1.98 day) (p less than 0.025); on stanozolol these declined to 3.19 +/- 0.41 (p less than 0.02) and 5.10 +/- 1.13 (p = 0.07), respectively, still significantly different from each other (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Estrogen-induced increase in uptake of cholesterol-rich very low density lipoproteins in perfused rabbit liver.

A nonrecirculating rabbit liver perfusion system was developed to test whether estrogen increases hepatic uptake of radio-iodinated normal and/or cholesterol-rich very low density lipoproteins (VLDL, d less than 1.006 g/ml) from cholesterol-fed rabbits. When equal concentrations of VLDL protein from normal rabbits and from cholesterol-fed rabbits were perfused together through the same liver, there was a selectively higher (1.4-fold) uptake of cholesterol-rich VLDL. These particles were rich in apolipoprotein E, and the radioactivity bound to this apolipoprotein was selectively removed by the perfused normal rabbit liver relative to its uptake of apolipoproteins B and C. When livers from estrogen-treated rabbits were perfused under identical conditions as normal livers and with the same lipoproteins, the uptake of cholesterol-rich VLDL was increased by 76%, compared with 21% for normal VLDL.

Effect of dietary lipids on hepatic and extrahepatic sterol 27-hydroxylase activity in high- and low-responding baboons.

Our previous studies found that low low-density lipoprotein (LDL)-responding baboons compared with high LDL-responding baboons have higher hepatic sterol 27-hydroxylase activity when consuming a high-cholesterol and high-fat (HCHF) diet. The present studies were conducted to determine whether the extrahepatic activity of sterol 27-hydroxylase is also higher in low-responding baboons and to assess whether the enzyme is regulated at the protein level. We measured the hepatic sterol 27-hydroxylase activity and protein level and plasma 27-hydroxycholesterol concentration in six low- and six high-responding baboons on both the basal and the HCHF diet. We also compared the sterol 27-hydroxylase activity in the adrenal gland and 27-hydroxycholesterol concentration in blood lymphocytes from high- and low-responding baboons consuming the HCHF diet. With the HCHF diet, the plasma 27-hydroxycholesterol concentration and hepatic sterol 27-hydroxylase activity and protein level increased rapidly in low responders, but not in high responders. Blood lymphocytes of low-responding baboons cultured in the presence of lipoprotein-deficient serum (LPDS) had lower cholesterol concentrations than those from high-responding baboons. Addition of exogenous 27-hydroxycholesterol to the culture medium of blood lymphocytes decreased the cellular cholesterol concentration. Plasma 27-hydroxycholesterol and hepatic sterol 27-hydroxylase activity and protein levels were negatively correlated with the plasma VLDL + LDL cholesterol concentration and VLDL + LDL/HDL cholesterol ratio after 6 weeks on the HCHF diet, but not on the chow diet. The results suggest that sterol 27-hydroxylase activity in both hepatic and extrahepatic tissues attenuates the dietary responsiveness in baboons, and the enzyme activity is not regulated by the specific activity of the protein.