Effect of smoking and smoking cessation on bone mass, bone remodeling, vitamin D, PTH and sex hormones.

OBJECTIVE: To assess the effect of smoking and smoking cessation on bone density, bone remodeling markers, sex hormones, and vitamin D-PTH axis in healthy young subjects. MATERIALS AND METHODS: We studied 74 healthy people (31 men, 43 women; mean age 32.2 (7) years) divided into 52 never smokers and 22 smokers, 15 of which stopped smoking for one month. RESULTS: Male smokers compared with never smokers showed lower BMD (0.971 (0.11) g/cm(2) vs. 1.069 (0.09) g/cm(2), P=0.042); higher plasma estrone levels (32.37 (10.13) pg/mL vs. 20.91 (5.46) pg/mL, P=0.001); and lower serum iPTH levels (16.2 (3.5) pg/mL vs. 28.8 (2.0) pg/mL, P=0.008). In women, BMD values were similar in smokers than in never smokers, but 25-hydroxyvitamin D levels were lower in smokers (31.9 (15.1) ng/mL vs. 16.8 (9.9) ng/mL, P=0.002). After adjusting by age and coffee consumption, female smokers had higher urinary-NTX levels than never smokers. After smoking cessation, statistically significant decreases of 25-hydroxyvitamin D and SHBG plasma levels were observed in men and women, respectively. CONCLUSIONS: Tobacco increases bone resorption and affects bone mass by some alterations in sex hormone metabolism, but also importantly by alterations on the vitamin D-PTH axis.

Osteoblasts in HIV-infected patients: HIV-1 infection and cell function.

BACKGROUND: HIV-infected patients have been shown to have a severe alteration in osteoblast function that appears to be related to the infection. OBJECTIVE: To determine whether normal human osteoblasts express CD4, whether osteoblasts from patients with HIV infection are infected by HIV-1 and whether osteoblast dysfunction observed in vivo also occurs in vitro. METHODS: Osteoblast cultures from bone marrow biopsies of HIV-infected patients (n = 14) and control patients (n = 10) were used in a cross-sectional study and a case-control prospective study. Expression of CD4 was analysed using flow cytometry and reverse transcriptase polymerase chain reaction; the presence of HIV-1 particles was determined by measuring p24 antigen in the supernatants of osteoblast cultures and viral DNA or RNA in the osteoblasts using the polymerase chain reaction. Osteoblast function was assessed by measuring cell proliferation, type I collagen and osteocalcin synthesis. RESULTS: In human osteoblasts, CD4 expression could not be determined using flow cytometry, although low levels of mRNA coding for CD4 were detected. HIV infection was not observed in osteoblast cultures from HIV-infected patients nor was there any alteration in replication and synthesis of type I collagen, although osteocalcin synthesis was increased. CONCLUSIONS: It is unlikely that HIV-1 infects human osteoblasts in vivo; therefore, the hypothesis that these cells could act as local HIV-1 reservoirs should be reconsidered.

Alcohol-induced bone disease in the absence of severe chronic liver damage.

To define and identify metabolic bone disease and mineral alterations induced by chronic heavy alcoholism in patients without severe liver damage, we studied a prospective series of unselected patients admitted to a 300-bed general hospital in Barcelona (Spain). A total of 26 chronic heavy drinkers of more than 150 g/day for at least 3 years were included. A general analytic and hormonal study, including liver biopsy in cases with any abnormality in liver function tests, and plasma and urine biochemistry with calcium regulating hormones and osteocalcin levels were determined. A transiliac bone biopsy after double-tetracycline labeling, with histomorphometric study of undecalcified bone, was performed. Statistical analysis was adjusted by age and sex by means of logistic regression. A total of 26 (20 men and 6 women) chronic alcohol abusers were studied. After adjustment for age and sex, alcoholic patients showed slight but significantly increased concentrations of plasma calcium (9.56 +/- 0.56; OR = 17.93; 95% CI 3.17-101.48) and decreased cPTH (0.36 +/- 0.11; OR = 0.097; 95% CI 0.018-0.528) compared with controls. Osteocalcin values were low (1.49 +/- 0.89, normal range 1.8-6.6). There was a significant decrease in bone volume, BV/TV (12.56 +/- 5.29; OR = 0.06; 95% CI 0.01-0.34), with increased resorption surfaces, ES/BS (4.28 +/- 2.43; OR = 9.86; 95% CI 2.16-45.07), and increased osteoclast number, N.Oc/TA (0.21 +/- 0.37; OR = 6.41; 95% CI 1.27-32.25).(ABSTRACT TRUNCATED AT 250 WORDS)

Osteoblastic proliferation in bone biopsies from patients with end-stage chronic renal failure.

Osteoblasts have traditionally been considered to be terminally differentiated cells and therefore unable to divide. Data in recent years, however, indicate that cellular differentiation does not usually preclude preservation of proliferative ability and that most differentiated cells are able to divide under adequate stimuli. The aim of this study was to assess whether cubic osteoblasts undergo proliferation during the formation phase of the remodeling cycle under a stimulus that increased bone turnover. For that purpose, the osteoblastic proliferation index (OPI) was analyzed by DNA image cytometry in transiliac bone biopsies from 33 patients with chronic renal failure (23 men, 10 women; mean age 50.4 +/- 15.1 years) who have been classified into low (n = 13), normal (n = 15), and high (n = 15) bone turnover according to activation frequency (Ac.f). OPI was significantly higher (p < 0.002) in the high bone turnover group (13.90 +/- 4.72%) compared with the low (2.38 +/- 4.13%) and normal turnover groups (2.84 +/- 4.04%). There was a positive correlation between OPI and the following histomorphometric parameters: bone formation rate, surface referent (r = 0.76, p = 0.00001), activation frequency (r = 0.73, p = 0.00001), mineral apposition rate (r = 0.73, p = 0.00001), bone formation rate, volume referent (r = 0.71, p = 0.00001), and mineralizing surface (r = 0.62, p = 0.0001). This study shows that a rise in bone turnover is associated with a marked increase of bone-forming cell proliferation in patients with end-stage chronic renal failure. From this finding, it may be concluded that cubic osteoblasts do not behave as "terminally differentiated" cells in vivo, because a high proportion of them are still able to divide.

Bone remodeling alterations in myelodysplastic syndrome.

There is a close relationship between hematopoietic bone marrow and bone cells. Thus, the profound derangement of hematopoiesis in myelodysplastic syndromes (MDS) might be expected to affect bone cell function. We studied the dynamic histomorphometric changes in bone in 22 MDS patients to examine this relationship and analyze the influence of hematological disease on bone remodeling. Bone-regulating hormones and histomorphometry of undecalcified transiliac bone biopsies, after double tetracycline labeling, were studied. Serum calcium, phosphorus, creatinine, alkaline phophatase, osteocalcin, iPTH, 25(OH)D3, 1,25(OH)2D3, hydroxyprolinuria, and calcium/creatinine ratio in urine were normal compared with controls. Histomorphometry showed a significant decrease in osteoblast surface (Ob.S/BS) (0.30 +/- 0.40 vs. 0.8 +/- 1.1, p = 0.031), wall thickness (W.Th), (22.03 +/- 5.5 vs. 31.8 +/- 5.8, p < 0.005), osteoclast number (N.Oc/T.Ar) (0.004 +/- 0.01 vs. 0.017 +/- 0.01, p = 0.03), mineral apposition rate (MAR) (0.16 +/- 0.15 vs. 0.53 +/- 0.19, p < 0.005), bone formation rate, surface referent (BFR/BS) (0.004 +/- 0.10 vs. 0.016 +/- 0.016, p = 0.009), and activation frequency (Ac.f) (0.06 +/- 0.07 vs. 0.21 +/- 0.23, p = 0.008). An increase in mineralization lag time (MLT) (119.2 +/- 78.6 vs. 29.6 +/- 77, p < 0.005), (mean +/- SD, unpaired Student t-test) was observed. Bone volume (BV/ TV), eroded surfaces (ES/BS), and osteoid thickness (O.Th) remained unchanged. This picture of adynamic bone with decreased mineral apposition rate and markedly decreased osteoclast number is a characteristic finding in MDS patients. Thus, bone histomorphometric finding in MDS patients show the relationships and interactions between hematopoietic and bone cells.

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)

Effect of alendronate on cultured normal human osteoblasts.

Alendronate is an aminobisphosphonate with a potent anti-reabsorptive action that does not appear to interfere with bone mineralization, and is even able to increase bone mineral density in osteoporotic postmenopausal women through a still not fully understood mechanism. This study was conducted to assess the direct effect of alendronate on diverse aspects of normal human osteoblast physiology. For that purpose, the in vitro effect of a wide range of concentrations [from 10(-1) to 10(-12) mol/L] of alendronate on cell viability, proliferation, collagen synthesis, and the mineral-depositing capacity of normal human osteoblasts was tested. Alendronate effects were examined at 48 and 96 h of culture in the presence or absence of fetal calf serum. In vitro alendronate affected osteoblast viability at concentrations equal to or higher than 10(-4) mol/L. At concentrations equal to or higher than 10(-3) mol/L, no viable cells were observed in cultures. In vitro alendronate at concentrations between 10(-5) and 10(-12) mol/L did not have any effect on the proliferative capacity of normal human osteoblasts determined by two different techniques: (1) tritiated thymidine incorporation to DNA and (2) cell counting. Collagen synthesis by normal human osteoblasts showed a tendency to decrease following incubation with alendronate supplemented with fetal calf serum. This decrease was only statistically significant after 96 h of culture; however, a dose-response effect could not be documented. Finally, no effect of alendronate was observed on calcium deposition in vitro by normal human osteoblasts at concentrations equal to or lower than 10(-5) mol/L. In conclusion, the present study shows that alendronate in vitro does not affect viability, proliferation, and mineral deposit capacity of normal human osteoblasts at the concentration at which it inhibits by 50% the resorptive capacity of osteoclasts that for this drug has been reported as 2 x 10(-9) mol/L.

Hypertension and nephrotoxicity in the rate of decline in kidney function in diabetic nephropathy.

Serum creatinine levels were determined prospectively every 2 to 3 months in 40 patients with diabetic nephropathy for a global observation period of 864 months. The monthly creatinine increasing rate was significantly lower in normotensive periods, mean arterial pressure (MAP) less than 115 mmHg, when compared with hypertensive periods, MAP greater than 125 mmHg. No significant difference was shown in periods with borderline hypertension (MAP between 115-124 mmHg). The mean creatinine increases were of 0.036 mg/dl/month, 0.3 mg/dl/month and 0.046 mg/dl/month respectively. Normotension was associated with a slowing down of the rate of decline in renal function in this group of moderate kidney failure with an initial mean serum creatinine of 2.26 mg/dl. The exposure of patients to nephrotoxics (aminoglycosides, and possibly anesthesia) significantly accelerated the decline in renal function: 0.39 mg/dl/month and 0.17 mg/dl/month respectively according to the concomitance or not of toxics and hypertension. The reported protective effect of diabetes against aminoglycosides nephrotoxicity in experimental conditions was not reflected in our clinical results. On the contrary, we suggest a possible enhanced sensibility of the diabetic patient with diabetic nephropathy to aminoglycosides leading to an acceleration of the progression of renal failure.

[Hemodialysis and complement (author's transl)]. / Hemodiálisis y complemento.

After observing alterations in the activity of the serum complement in patients undergoing periodic hemodialysis, the authors performed a preliminary study to determine repeatedly the activity of C3, C4, and CH50 in 44 patients. They discovered a consistent drop in C3 and CH50 while C4 remained normal. An attempt to explain these findings with information from the literature offered no more than a hypothesis for further study. While the possibility of a decline in the synthesis of the complement factors cannot be disregarded, the authors believe it is much more probable that they are consumed at a rate higher than normal. Since the C4 factor does not appear to be involved, activation is probably along the alternative pathway. Defective synthesis cannot be attributed to liver disease because the latter is not always present and because there is no relationship between C3 levels and levels of albumin or the presence of hepatopathy. The literature was reviewed for data that might support the idea that the complements in these patients are activated continuously by some process in connection with dialysis, by chemical products employed for to clean the machines, by commonly administered drugs, etc. Because so few data could be found on the subject, the authors consider that is necessary to study these mechanisms and their repercussions over a longer period of time.

[Screening for bone disease risk with clinical factors in women after physiologic menopause]. / Cribado de riesgo óseo mediante factores clínicos en mujeres tras menopausia fisiológica.

BACKGROUND: Densitometric screening for osteoporosis in postmenopausal women has not been demonstrated cost-effective. We have tried to identify clinical factors for screening previous to densitometry avoiding unnecessary explorations. SETTING: outpatient clinics of a menopausal unit in a 450-bed general hospital. Cross-sectional study, in two steps, of two groups of 140 and 284 women attending for physiological menopause. A clinical questionnaire, physical data and lumbar densitometry (Hologic QDR 1000) were obtained classifying the cases as "normal" or "low bone mass" (osteopenia or osteoporosis) according with the WHO criteria. In the first group a logistic regression analysis was done to identify predictive factors for abnormal densitometry, then validated in the second group. Sensitivity, specificity, predictive values (PV) and classification ability of clinical factors were analyzed. RESULTS: Four factors were independent predictors of abnormal densitometry: age > 51 (odds ratio [OR] = 6.64; 95% CI, 2.36-18.7); body weight < 70 kg (OR = 4.32; 95% CI, 1.71-10.09); years of fertility < 32 (OR = 3.77; 95% CI, 1.36-10.04), and number of live births > 2 (OR = 3.47; 95% CI, 1.27-9.53). Presence of one factor offers: sensitivity 91.9%; specificity 15%; positive PV 66.6%, and negative PV 50%, whereas the presence of two factors offers: sensitivity 62.7%; specificity 70%; positive PV 79.9%, and negative PV 50.3%. Clinical screening allows, when two factors are present, to avoid a 35.5% of densitometries and the false-negative cases represent 18%. CONCLUSIONS: Detection of bone-risk clinical factors (abnormal densitometry) yields a screening, previous to densitometry, that avoids at least one third of explorations in women with physiological menopause, improving the efficiency of the test.