Calculated low-density lipoprotein cholesterol should not be used for management of lipoprotein abnormalities in patients with diabetes mellitus.

OBJECTIVE: To assess the validity of calculated low-density lipoprotein cholesterol by the Friedewald formula for management of lipoprotein abnormalities in patients with diabetes mellitus. RESEARCH DESIGN AND METHODS: Calculated LDL cholesterol by the Friedewald formula was compared with measured LDL cholesterol after separation by ultracentrifugation in 61 patients with type I diabetes, 50 patients with type II diabetes, and 116 healthy control subjects. RESULTS: Calculated LDL cholesterol coincided with measured LDL cholesterol, with < 10% error, in 54 (49%) patients with diabetes mellitus, and 85 (73%) control subjects. Calculated LDL cholesterol was overestimated, with an error of > or = 10% of measured LDL cholesterol in 39% of patients and 26% of control subjects, and underestimated in 13 and 1%, respectively. Despite a good correlation between calculated and measured LDL cholesterol, the intraclass correlation coefficients demonstrated a poor concordance between calculated and measured LDL cholesterol, both in patients and control subjects. When comparing the mean differences of calculated and measured LDL cholesterol for diabetic subjects versus control subjects, significantly greater differences in type II (but not type I) diabetic subjects were seen. CONCLUSIONS: Calculation of LDL cholesterol by the Friedewald formula may be inaccurate for assessment of cardiovascular risk in patients with type II diabetes and may not be appropriate for management of lipoprotein abnormalities in those diabetic patients.

Relationship between lipoprotein profile and urinary albumin excretion in type II diabetic patients with stable metabolic control.

OBJECTIVE: To assess lipids and lipoprotein composition and the relationship between lipoprotein abnormalities and urinary albumin excretion (UAE) in select type II diabetic patients with stable metabolic control. RESEARCH DESIGN AND METHODS: Fifty-five type II diabetic patients and 55 healthy control subjects both with a body mass index < 30 kg/m2 were studied. Patients were classified according to their level of UAE as normoalbuminuric (n = 37), microalbuminuric (n = 11), and macroalbuminuric (n = 7). In all cases, serum creatinine and albumin concentrations were in the normal range. RESULTS: Normoalbuminuric patients showed increased triglyceride (TG) contents in intermediate-density lipoprotein (IDL) (P < 0.01), low-density lipoprotein (LDL) (P < 0.001), and high-density lipoprotein (HDL) (P < 0.001) compared with control subjects. Lipoprotein concentration in microalbuminuric patients did not differ from that of normoalbuminuric patients. On the other hand, patients with macroalbuminuria showed a significant increase in IDL cholesterol (P < 0.01) and IDL (P < 0.01), LDL (P < 0.05), and HDL TGs (P < 0.01) compared with the other groups. Diabetic patients with nephropathy, both microalbuminuric and macroalbuminuric, tended to have higher mean lipoprotein(a) (Lp[a]) concentrations than normoalbuminuric patients and control subjects. A strongly positive correlation was observed between UAE and serum TGs (r = 0.56) and very-low-density lipoprotein (r = 0.55), IDL (r = 0.52), LDL (r = 0.54), and HDL TGs (r = 0.52). CONCLUSIONS: Lipoprotein alterations observed in diabetic patients, specifically IDL abnormalities and a tendency toward high Lp(a) levels, which are more marked in those with increased UAE, may contribute to the excess of cardiovascular disease in type II diabetic patients, particularly those with nephropathy.

Pulmonary tuberculosis in HIV-infected patients with normal chest radiographs.

SUBJECTS: Three HIV-infected patients with active pulmonary non-disseminated tuberculosis and normal chest radiograph at clinical presentation and during follow-up are reported. Patients had cough and fever but no other specific symptoms. Löwenstein cultures of specimens from bronchoalveolar lavage in two cases and induced sputum in one yielded Mycobacterium tuberculosis. CONCLUSIONS: The diagnosis of tuberculosis in HIV-infected patients depends greatly on clinical suspicion by the physician, because of its atypical presentation. Failure to perform appropriate diagnostic tests in HIV-infected patients who present with suspected pulmonary disease will result in underdiagnosis and undertreatment of tuberculosis.

PIP: Between 1984-1991, physicians at Hospital del Mar in Barcelona, Spain and the area with the highest prevalence of tuberculosis (TB) diagnosed active pulmonary nondisseminated TB in 57 HIV infected patients. 3 of these patients consistently had normal chest radiographs. All 3 patients had fever and cough. Case 1 was a 26 year old female intravenous (IV) drug user. She had generalized lymphadenopathy. Hematologic tests revealed an HIV positive status. Her CD4+ lymphocyte count was 782 x 10 to the 6th power/1. Her tuberculin skin test was negative. Mycobacterium tuberculosis in her sputum grew in Lowenstein medium. Acid fast bacilli were detected in her sputum with Ziehl-Nielsen stain. Physicians began antiTB therapy (isoniazid, pyrazinamide, rifampin, and ethambutol). She improved within a few weeks. Case 2 was an HIV positive IV drug user and 33 years old. The CD4+ lymphocyte count was 645 x 10 to the 6th power/1. Acid fast bacilli were detected in his bronchoalveolar lavage with Ziehl-Nielsen stain. M. Tuberculosis in the lavage grew in Lowenstein medium. The physicians started him on the same antiTB therapy as Case 1. His condition improved with therapy. Case 3 was a 50 year old bisexual man. Hematologic tests showed HIV positivity. His CD4+ lymphocyte count was 790 x 10 to the 6th power/1. Further his tuberculin skin test was negative. Fibre optic bronchoscopic samples were negative for acid fast bacilli, but M. tuberculosis grew in Lowenstein culture. Blood, urine, bone marrow and gastric aspirates tested negative for M. tuberculosis. He began the same antiTB therapy as Cases 1 and 2. His condition improved. In conclusion, physicians should aggressively pursue a diagnosis to TB in HIV infected patients presenting with fever and cough. Their rate of hospitalization should fall with early diagnosis and treatment which will in turn prevent the spread of TB among the population.

Long-term thyroid replacement therapy and levels of lipoprotein(a) and other lipoproteins.

There is a general interest to know whether lipoprotein(a) [Lp(a)] is under hormonal control. Hypothyroidism is a well known cause of secondary hyperlipidemia, which mainly affects low density lipoprotein (LDL) cholesterol levels, but the result on the effects of L-T4 replacement therapy on the Lp(a) concentration is controversial. We studied 12 severely hypothyroid, hypercholesterolemic patients under basal conditions and during L-T4 treatment. We found a rapid decrease in both LDL cholesterol (5.71 +/- 0.62 vs. 4.37 +/- 0.44 mmol/L basally and after 1 month of thyroid replacement, respectively) and apolipoprotein-B (Apo-B) levels (1.89 +/- 0.02 vs. 1.52 +/- 0.17 g/L, respectively); these changes persisted for up 1 yr of analytical euthyroidism and paralleled the improvement in the thyroid status of the patients. In contrast, the plasma Lp(a) concentration did not change at any time (496 +/- 123, 464 +/- 128, and 441 +/- 110 mg/L under basal conditions and after 1 and 14-15 months of thyroid replacement, respectively), and the small fluctuations observed in some patients did not correlate with those in LDL cholesterol or Apo-B, and were not associated with any particular Apo(a) phenotype. In relation to HDL fractions, high density lipoprotein3 (HDL3) remained stable, but HDL2 cholesterol and phospholipid levels decreased during treatment, changes that were the inverse of those in postheparin plasma hepatic lipase activity. Patients in the present study were normotriglyceridemic, except one who was hypertriglyceridemic at diagnosis, but even in this patient, triglyceride levels were unaffected by T4 substitution therapy, as was postheparin plasma lipoprotein lipase activity. The changes observed in LDL, HDL2, and hepatic lipase activity delineate the lipoprotein-related response to T4 replacement therapy, whereas potential individual fluctuations in Lp(a) levels are probably more dependent on other factors, such as the production rate, which are not affected by thyroid hormones.

Bone remodelling in human immunodeficiency virus-1-infected patients. A histomorphometric study.

The aim of this study was to identify and describe possible alterations of bone histomorphometry in patients with human immunodeficiency virus (HIV-1) infection and to assess the relation between these alterations and disease severity. Forty-four HIV-1-infected patients seen successively at our hospital were evaluated for the study. In an attempt to avoid confounding factors as far as possible, we excluded patients who fulfilled any of the following criteria: age less than 18 or greater than 40 years; recent history of extended bed rest; previous diagnosis of metabolic bone disease, renal insufficiency, or hepatic failure; clinical or echographic signs of liver cirrhosis; diabetes mellitus or previous diagnosis of other endocrine diseases; drug therapy that could act on bone metabolism; and/or moderate to severe nutritional alteration. Twenty-two patients (13 men, 9 women; age: 27.9 +/- 4.1 years, mean +/- standard deviation) were included in the study. Plasma and urine biochemistry and calcium-regulating hormones were determined. Bone mineral content was measured on vertebrae L2 to L4 and on the neck and intertrochanteric areas of the femur by dual-photon absorptiometry. A transiliac bone biopsy was performed after double-tetracycline labelling, with histomorphometric study of undecalcified bone. Serum osteocalcin was found to be lower in patients who, according to the Centers for Disease Control (CDC) classification, had greater disease severity, and showed a positive correlation with the number of CD4+ T lymphocytes. No alterations in bone densitometry were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoprotein(a) genetic polymorphism and serum lipoprotein(a) concentration in patients with peripheral vascular disease.

Serum lipoprotein(a) (Lp(a)) levels were measured in 89 men with peripheral vascular disease (PVD) and 129 (100 male and 29 woman) healthy controls. Apolipoprotein(a) genetic polymorphism was determined by immunoblotting in all subjects. Patients with PVD had significantly higher serum Lp(a) levels than controls. Apolipoprotein(a) phenotype frequencies in patients with PVD did not differ from those of the control group. Both patients and controls with phenotype S2 had higher serum Lp(a) levels than those with phenotype S4. It should be emphasized that serum Lp(a) levels were significantly higher in PVD patients than controls for those with phenotype S2, S3/S4 and S4. Raised serum Lp(a) levels together with other lipoprotein abnormalities in patients with PVD imply a high cardiovascular risk. Genetic polymorphism clearly influences serum Lp(a) levels both in patients and controls. In patients with PVD, environmental and/or other genetic factors must play a role in raising Lp(a) levels.

The evolution of alpha heavy chain disease.

Two patients with alpha heavy chain disease are described. In the first patient, treatment with cyclophosphamide, prednisone and doxycycline was associated with a 28 month-long remission and the disappearance of the paraprotein and lymphoplasmocytic infiltration of the intestine. Shortly afterwards, a retroperitoneal immunoblastic lymphoma was found associated with an immunoglobulin G-kappa-paraproteinemia, and gamma heavy and kappa-light chains in the urine; the intestinal biopsy specimen was normal. In the other patient, the alpha chain only appeared two years after the malabsorption syndrome. The fact that in the first, apparently cured patient, a tumor of different anatomic site and secretory capacity appeared, suggests the existence of a B-cell neoplasia of different clone from that which gave rise tothe original disease. In the second patient, it is probable that only the increase in the mass of neoplastic cells led to the detection of the protein abnormality, or alternatively the antigenic-oncogenic stimulus led to the abnormal secretion only after two years.

Hormonal profile and serum zinc levels in uraemic men with gonadal dysfunction undergoing haemodialysis.

Serum gonadal hormones, gonadotrophins and zinc levels were studied in thirteen men aged 29-62 yr with chronic renal failure undergoing haemodialysis. All patients had decreased libido and impotence. Serum testosterone levels in patients (18.5 +/- 1.3 (SEM) nmol/l) were significantly lower (p less than 0.05) than in the control group (24.1 +/- 2.2 (SEM) nmol/l) although salivary testosterone levels were strictly within the normal range. Mean serum 17-beta-oestradiol and luteinizing hormone levels (0.19 +/- 0.03 (SEM) nmol/l, and 57.4 +/- 13.1 (SEM) IU/l, respectively) were significantly higher (p less than 0.05 and p less than 0.005, respectively) than in the control group (0.11 +/- 0.02 (SEM) nmol/l and 14.8 +/- 1.9 (SEM) IU/l, respectively). Mean progesterone and follicle-stimulating hormone levels in patients were not significantly different from those of control subjects. Mean prolactin values in patients (1,019 +/- 285 (SEM) mIU/l) were significantly higher (p less than 0.01) than in the control group (211 +/- 24 (SEM) mIU/l). Serum prolactin levels in five patients were extremely high (above 1,200 mIU/l). There was no statistically significant difference in serum zinc levels between patients and controls. As salivary testosterone is normal, it seems that hyperprolactinaemia and raised serum 17-beta-oestradiol levels may be responsible, at least in part, for sexual dysfunction in male patients with chronic renal failure receiving haemodialysis.

Differential expression of double-band apolipoprotein(a) phenotypes in healthy Spanish subjects detected by SDS-agarose immunoblotting.

A sodium dodecyl sulphate-agarose apolipoprotein(a) [apo(a)] phenotyping method was set up to attain accurate scanning densitometry of proteins. Serum samples from 99 healthy Spanish men were analysed and twenty-five different apo(a) isoforms (12 to 37 kringle 4 repeats) were detected. Double-band phenotypes accounted for 39.4% (n = 39) and three different patterns of protein expression were identified: pattern A (20.5% of double-band phenotyped samples) predominantly expressed the highest molecular weight isoform; pattern B (53.9%) mainly the lowest molecular weight isoform, and pattern AB (25.6%), expressed both isoforms equally. A significant linear association between expression pattern and lipoprotein(a) [Lp(a)] concentration > or = 0.30 g/l was observed. Single-band phenotyped samples (n = 60) were stratified according to apo(a) kringle 4 repeat categories and showed that 90% of isoforms < 20 K4 repeats had high Lp(a) concentrations (> or = 0.30 g/l), whereas isoforms with 20 to 24 or more than 24 kringle 4 repeats had Lp(a) concentrations > or = 0.30 g/l in 47% and 14%, respectively. A logistic regression model was fitted to test the association between apo(a) size, expression pattern and Lp(a) concentration. In this model, apo(a) isoform < 25 kringle 4 repeats was significantly associated with serum Lp(a) concentration > or = 0.30 g/l in both single and double-band phenotyped samples (odds ratio = 8.9, p < 0.001). In the latter, a differential expression pattern with respect to smaller size isoforms (pattern AB vs A) was significantly associated with Lp(a) concentration > or = 0.30 g/l (odds ratio = 17.97, P = 0.045). Heterogeneity in protein apo(a) size expressed according to kringle 4 repeat number could be categorized in heterozygous phenotypes as three patterns. When small-sized isoform was expressed (pattern B) or both isoforms were equally expressed (pattern AB), the probability of having Lp(a) > or = 0.30 g/l is higher.

The effect of heparin on serum lipoprotein-X.

Serum lipoprotein-X was investigated in 12 patients with cholestasis in basal conditions and 20 minutes after intravenous heparin. In all cases, lipoprotein-X was positive in the first sample and became negative after heparin. A decrease in triglycerides was observed in all patients after heparin with an increase in free fatty acids and mobilization of prebetalipoproteins, and a transformation of lecithin into lysoleithin in 4 cases after heparin. These facts suggest that heparin plays an important role in the mobilization of serum lipoprotein-X.

The clearance of lipoprotein X in vitro, and effect of phospholipase A on serum lipoprotein X.

The in vitro effect of post-heparin and post-heparin plus post-protamine normal serum on serum lipoprotein X (LP-X) is described. Serum LP-X is cleared after incubation with post-heparin normal serum, and serum LP-X remain unmodified when it is incubated with post-heparin plus post-protamine normal serum. The action of phospholipase A from snake venom on serum LP-X is also studied. A very small quantity of phospholipase is necessary to degrade LP-X and to transform lecithin into lysolecithin. It is concluded that phospholipase seems to be the enzyme that most likely induces the LP-X changes after heparin administration.

Lipoprotein composition in the insulin-deficient non-acidotic phase of type I diabetic patients and early evolution after the start of insulin therapy.

Lipoproteins, including intermediate density lipoproteins and lipoprotein(a), and apolipoproteins A-I, B, C-II, C-III and E, were studied in 13 newly-diagnosed type I diabetic patients with severe insulinopenia without dehydration or acidosis. At baseline, the main finding was a significant increase in serum triglycerides due to raised triglyceride concentrations in all lipoproteins, particularly triglyceride-rich lipoproteins. Cholesterol concentrations were slightly increased in lipoproteins and led to a significant increase in serum cholesterol. Two days after the start of insulin therapy, lipoprotein profiles had normalized except for the LDL triglyceride contents, which remained significantly increased on the fifth day of treatment. No significant modifications were observed in lipoprotein(a), apolipoproteins A-I and E concentrations throughout the study. However, serum apolipoproteins B, C-II and C-III were increased at baseline and fell to normal levels 2 days after the start of insulin therapy. On the other hand, apolipoprotein C-II/C-III ratios in high and very low density lipoprotein, showed no significant differences at baseline compared with controls, suggesting that an apolipoprotein C-II deficiency or apolipoproteins Cs imbalance can be ruled out. In conclusion, significant lipoprotein abnormalities were observed in the insulin-deficient state of type I diabetes mellitus; insulin therapy normalizes the lipoprotein profile in two days, except for low density lipoprotein triglyceride contents which remain increased at the fifth day.

Interaction of family history of atherosclerosis with atherogenic lipid traits in men with non-coronary atherosclerosis.

Family history of atherosclerosis has been recognised as an nonmodifiable cardiovascular risk factor. Lipid levels, together with hypertension and diabetes, appear to have an inheritable component. The aim of the study was to ascertain whether lipoprotein abnormalities of 169 adult patients with non-coronary atherosclerosis were associated with a family history of atherosclerosis. Besides intermediate density lipopoprotein composition and Lp(a) levels, we focused on apo(a) and apo E phenotypes, LDL cholesterol/apo B ratio, VLDL triglyceride/HDL cholesterol ratio, and environmental factors. We found that patients with a family history of atherosclerosis had a higher prevalence of VLDL triglyceride/HDL cholesterol ratio above 1.8 (51.3% vs 34.7%) than patients without. Similarly, there was a significant inverse correlation between both considered ratios (r = -0.24, p < 0.05). The odds ratio of the presence of both abnormal ratios (4.60, 95% CI, 1.41-15.00) and low molecular weight apo(a) isoforms (3.30, 95% CI, 1.05-10.30 and family history of atherosclerosis was independent of smoking and hypertension. Apo(a) isoform size seems to be more important than Lp(a) concentrations in the family history of atherosclerosis risk determination. Subsequent analysis showed that patients with a family history of atherosclerosis had a greater-than-fourfold increased risk of having one or both abnormal ratios reflecting metabolic disturbances which probably constitute a combined trait. Family history of atherosclerosis may constitute a specific lipoprotein-related marker of atherosclerosis. Such a marker often precedes the onset of overt disease and may contribute to identifying patients with an atherogenic lipoprotein profile even in the absence of classical lipid risk factors.

Decreased endogenous antioxidant enzymatic status in essential hypertension.

Several lines of evidence suggest that patients with essential hypertension have impaired endothelial nitric oxide activity and increased superoxide anion production. However, the mechanisms underlying these abnormalities remain unknown. We measured enzymatic superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities in erythrocytes and whole blood, respectively, in 30 newly-diagnosed, normolipidaemic untreated mild hypertensive patients and in 164 age-matched healthy controls. SOD and GPX activities in hypertensive patients (806 +/- 225 U/Hb.g and 5491 +/- 2073 U/L, respectively) were significantly lower than in the control group (931 +/- 202 U/Hb.g and 6669 +/- 1560 U/L, respectively) (P < 0.005). No significant association was found between these antioxidant enzyme activities and blood pressure in normotensive controls. In the hypertensives, only log-transformed SOD activity showed a significant negative correlation with systolic and diastolic blood pressure (r = 0.37, P < 0.05; r = 0.64, P < 0.0001, respectively). The low endogenous antioxidant enzyme activities observed may in turn result in decreased superoxide anion removal leading to nitric oxide inactivation. Journal of Human Hypertension (2000) 14, 343-345

Radiographic findings in pulmonary tuberculosis: the influence of human immunodeficiency virus infection.

The chest radiographs and medical records of 166 patients diagnosed as having clinically active pulmonary tuberculosis were reviewed. Forty-nine patients (group I) were seropositives to human immunodeficiency virus (HIV), and 117 patients (group II) did not have known risk factors for HIV infection. Roentgenographic abnormalities were analysed in the two groups, according to nine different radiographic patterns previously defined. The seropositive group had a significantly higher proportion of hilar and/or mediastinal adenopathy (P less than 0.001), infiltrates confined to the lower lung fields (P less than 0.05), and miliary tuberculosis (P less than 0.005). Otherwise, single cavitation and destructive pattern were more frequent in the group II. These data suggest that patients with pulmonary tuberculosis and HIV infection are much more likely to have atypical radiographic findings.

Secondary prevention of coronary heart disease in patients with extracoronary atherosclerosis: a need for accuracy of low density lipoprotein determination.

According to the new guidelines of the National Cholesterol Education Program (NCEP) for secondary prevention in adults with evidence of coronary heart disease or other clinical atherosclerotic disease, lipoprotein analysis is required and classification is based on low density lipoprotein (LDL) cholesterol. The aim of the present study was to analyze the reliability of calculated LDL cholesterol by the Friedewald formula compared with measured LDL cholesterol after separation by ultracentrifugation in 202 male patients with extracoronary atherosclerosis (100 patients with ischemic cerebrovascular disease and 102 patients with peripheral vascular disease) and in 117 health control subjects. Calculated LDL cholesterol coincided with measured LDL cholesterol, with less than 10% error, in 118 patients (58.4%) with extracoronary atherosclerosis and in 87 controls (74.4%). Calculated LDL cholesterol was overestimated, with an error of 10% or more compared with measured LDL cholesterol, in 34.6% of patients and 22.2% of controls, and underestimated in 6.9% and 3.4% respectively. Despite a good correlation between calculated and measured LDL cholesterol, the intraclass correlation coefficients demonstrate a poor concordance between calculated and measured LDL cholesterol, both in patients and controls. The authors underline the need for caution in assessing the reliability of calculated LDL cholesterol.

Serum lipoprotein (a) levels in men with peripheral vascular disease.

The authors quantified serum lipoprotein (a) (Lp) (a) by enzymo-immuno-analysis in 86 outpatient men suffering peripheral vascular disease (PVD) and in 53 age-matched healthy men. They further measured serum cholesterol, serum triglycerides, low density lipoproteins-cholesterol, high density lipoproteins (HDL)-cholesterol and serum apolipoprotein B. Serum triglycerides were significantly increased in patients with PVD versus controls (148 +/- 8 and 114 +/- 7 mg/dL, mean +/- SEM). HDL-cholesterol levels were significantly lower in patients versus controls (36 +/- 1 and 43 +/- 2 mg/dL, respectively). Serum Lp(a) levels in patients with PVD were 20 +/- 2 mg/dL, whereas in controls they were 16 +/- 3 (p: NS). Serum Lp(a) concentrations were identical in smoker and nonsmoker patients. There was no correlation between Lp(a) concentration and the other lipid parameters. Conversely, as occurs in coronary heart disease and in cerebrovascular disease, Lp(a) does not seem to be a marker for PVD, although a trend toward a higher mean levels was found.

[Hyperalphalipoproteinemia: study of a family]. / Hiperalfalipoproteinemia: estudio de una familia.

A family with hyperalphalipoproteinemia is described, being exceptional the longevity of some of their members. The proband, a 36 years-old woman with excellent health, showed total cholesterol levels of 6.77 mmol/l, HDL-cholesterol 3.00 mmol/l and apoprotein (apo) AI 2.4 g/l. HDL-cholesterol levels of her mother and two sisters were 1.86, 2.07 and 2.02 mmol/l, respectively. Their serum apo AI levels were 2.11, 2.32 and 2.30 g/l, respectively. It is to emphasize about the necessity to investigate the serum HDL-cholesterol, mainly in subjects with moderate hypercholesterolemia, to detect possible hyperalphalipoproteinemia.

[Portal hypertension in chronic lymphatic leukemia (author's transl)]. / Hipertensión portal en la leucemia linfática crónica.

A syndrome of portal hypertension with hemorrhagic ascites was developed in a 44-year-old patient, 2 years after he had been diagnosed as having a chronic lymphatic leukemia. The study of the patient, including two liver biopsies and a laparoscopy, excluded the existence of another hepatic or extrahepatic associated condition. The clinical course of the patient was rapidly fatal progressive in spite of the cytostatic therapy, and he died as a result of an acute liver failure. The autopsy confirmed the absence of vascular occlusions in the suprahepatic veins or in the vena porta. The liver showed, in contrast to the findings of previous biopsies and laparoscopy, an evident fibrotic pattern.

[Bile acids. I. Nature, physiology, and functions (author's transl)]. / Acidos biliares. I. Naturaleza, fisiología y funciones.

Bile acids play a fundamental role in the degradation and absorption of intestinal lipids. The primary ones are cholic acid and chenodeoxycholic acid which are synthesized from cholesterol in the liver and conjugate with taurine and glycine amino acids. The secondary bile acids are derived from the primary ones by the enzyme action of intestinal bacteria through a process of deconjugation and dehydroxylation. Their detergent property is based on the molecular configuration of these compounds, which present a hydrophilic and a hydrotion of these compounds, which present a hydrophilic and a hydrophobic surface. The different enzymes in the liver cells that intervene in the process of synthesis of bile acids are now known. A basic element in their physiology is the enterohepatic circulation, enabling the organism to take maximum advantage of these compounds. The dynamics of the cycle are maintained and regulated by the system of uptake and secretion of the cells, cholecystokinin, intestinal peristalsis, active transport across the ileal membrane, and by portal venous flow. Much of our knowledge about the biogenesis and functions of the bile acids has been acquired quite recently. Research over the past three decades has contributed to a great advance in our understanding of their physiology.