Priscille G. Massé

Pyridoxine deficiency affects biomechanical properties of chick tibial bone

The mechanical integrity of bone is dependent on the bone matrix, which is believed to account for the plastic deformation of the tissue, and the mineral, which is believed to account for the elastic deformation. The validity of this model is shown in this study based on analysis of the bones of vitamin B6-deficient and vitamin B6-replete chick bones. In this model, when B6-deficient and control animals are compared, vitamin B6 deficiency has no effect on the mineral content or composition of cortical bone as measured by ash weight (63 +/- 6 vs. 58 +/- 3); mineral to matrix ratio of the FTIR spectra (4.2 +/- 0.6 vs. 4.5 +/- 0.2), line-broadening analyses of the X-ray diffraction 002 peak (beta 002 = 0.50 +/- 0.1 vs. 0.49 +/- 0.01), or other features of the infrared spectra. In contrast, collagen was significantly more extractable from vitamin B6-deficient chick bones (20 +/- 2% of total hydroxyproline extracted vs. 10 +/- 3% p < or = 0.001). The B6-deficient bones also contained an increased amount of the reducible cross-links DHLNL, dehydro-dihydroxylysinonorleucine, (1.03 +/- 0.07 vs. 0.84 +/- 0.13 p < or = 0.001); and a nonsignificant increase in HLNL, dehydro-hydroxylysinonorleucine, (0.51 +/- 0.03 vs. 0.43 +/- 0.03, p < or = 0.10). There were no significant changes in bone length, bone diameter, or area moment of inertia. In four-point bending, no significant changes in elastic modulus, stiffness, offset yield deflection, or fracture deflection were detected. However, fracture load in the B6-deficient animals was decreased from 203 +/- 35 MPa to 151 +/- 23 MPa, p < or = 0.01, and offset yield load was decreased from 165 +/- 9 MPa to 125 +/- 14 MPa, p < or = 0.05. Since earlier histomorphometric studies had demonstrated that the B6-deficient bones were osteopenic, these data suggest that although proper cortical bone mineralization occurred, the alterations of the collagen resulted in changes to bone mechanical performance.

Vitamin B6 deficiency experimentally-induced bone and joint disorder: microscopic, radiographic and biochemical evidence.

In the present study the effect of pyridoxine deficiency on the ultrastructure and morphology of bone and its metabolism was examined in the rapidly growing chick. Pyridoxine-deficient animals had tibias of reduced dry weight and cortical thickness. Histomorphometry demonstrated a disproportionately high eroded surface, lower amount of osteoid tissue and reduced mineralized trabecular width. Anterior-posterior radiographs of the tibiotarsometatarsal joint showed reduced secondary ossification centres and coarse trabeculation. Decalcified metaphyseal cartilage showed irregular trabeculas and a markedly reduced amount of Fast-green counterstain matrix suggesting that there is less collagen present and in turn less availability for matrix to be laid down for later calcification. Plasma activity of the bone alkaline phosphatase isoenzyme (EC 3.1.3.1) was decreased. Plasma Ca and PO4 levels did not vary. The present bone study referring to a pseudo-lathyritic state in which collagen maturation is not completely achieved supports the hypothesis that pyridoxine is an essential nutrient for the connective tissue matrix.

A Cartilage Matrix Deficiency Experimentally Induced by Vitamin B6 Deficiency

Abstract A vitamin B6-deficiency-induced disorder in avian articular cartilage resembling osteoarthritis has been further characterized. We measured several parameters of proteoglycan (PG) metabolism, i.e., fixed charge density and sulfated glycosaminoglycans (S-GAG) content in PN-deficient versus control articular cartilage and synovial fluid from the knee joint. Statistically significant changes were: 1) decreased content and increased extractability of total sulfated PGs from articular cartilage with guanidine HCI; 2) elevation of S-GAG concentration in synovial fluid; 3) increased plasma cystathionine (sulfur amino acid) levels. PG synthesis as assessed by 35SO4 incorporation into S-GAGs was not impaired. A lack of cartilage swelling in 0.15 M saline and the normal water content indicated that although disturbed, the collagen network was not disrupted. This finding was in agreement with a previous microscopic study that revealed no fissures in the articular cartilage. Previous findings of a normal aggregating PG size-distribution and absence of elevated metallo-proteases made a disturbance of aggregating PG metabolism unlikely. Escape into the synovial fluid of small PGs, normally bound to articular collagen, was believed to result from an alteration in collagen molecular organization that could be secondary to elevated circulating SH-compounds.

Long-term effect of low-dose combined steroid contraceptives on body iron status.

The present study was aimed to evaluate iron metabolism in active and healthy adult women having taken oral contraceptives (OC) long-term. Mean dietary iron intake in age-matched control and experimental groups was adequate. Serum ferritin used as a marker for body iron stores was marginal in both groups underlying a high prevalence of deficient-iron reserves among subjects. This parameter was not correlated to the iron content of the diet. The serum iron concentration was significantly higher in OC users than control subjects (p less than 0.001). Biochemical results commanded a discussion on the pertinence of evaluating the total dietary iron intake and on the sensitivity of biochemical methods used to assess the iron status.

Effects of dietary proteins and yeast Saccharomyces cerevisiae on vitamin B6 status during growth

Male rapidly growing broiler chicks were fed a moderate (22%) or a high protein (30%) well-balanced diet containing yeast Saccharomyces cerevisiae (2%) and consisting of soy protein isolate (Soyamin) or a purified amino acid mixture. The vitamin B6 status was assessed according to the in vitro stimulated activity of aspartic aminotransferase (activation coefficient; AC) and pyridoxal phosphate concentrations in plasma and erythrocytes. No weight difference was found between age-matched control and B6-deficient animals fed the Soyamin diet containing yeast. None of the deficient animals presented signs of malfunctions of the central nervous system. These animals grew well and their skeletal development was normal after 6 weeks of age. Due to the presence of yeast, increasing dietary protein intake did not augment the metabolic requirement for pyridoxine. The removal of yeast from the Soyamin diet provoked a severe symptomatic deficiency (AC 1.5). It seemed that yeast did more than promoting growth. It also protected against a lack of vitamin B6: feed utilization was not impaired. The present study showed that a low level of 0.6 mg vitamin B6/kg in a corn-Soyamin diet containing yeast was adequate to maintain normal growth and to avoid neurological symptoms. The pyridoxine requirement for normal growth and absence of convulsions has been reported to be approximately 3 mg/kg diet.

Relationship between Oral Contraceptives, Iron Status and Psychoaffective Behavior

Relatively few studies have been undertaken to correlate biochemical variables with psychological measurements. The present study aimed to delineate the relationship between iron status and psychoaffective behavior in active and healthy women taking or not taking oral contraceptives (OCs). The MMPI (Minnesota Multiphasic Personality Inventory) was used to assess the psychoaffective status. Although dietary iron intake in both groups was adequate, serum ferritin used as a marker for body iron stores was marginal, indicating a high prevalence of deficient iron reserves among subjects. The serum iron concentration was significantly higher in OC users than control subjects (p<0–001). The correlation analysis showed an inverse relationship (but not significant) between psychometric data and iron status, that is, a lower performance on some clinical scales (particularly those used to detect symptoms such as irritability, aggressiv-ity and anxiety) in subjects having lower serum iron and ferritin concentrations....

Testing the Tyrosine/Catecholamine Hypothesis of Oral Contraceptive-Induced Psychological Side-Effects: A Controlled Study on Triphasil®

Background: This study was conducted to probe the existence of oral contraceptive (OC)-induced psychological side effects that might be undetectable by psychometric testing. Methods: Triphasil® was administered during six complete menstrual cycles to young never-OC-users. Plasma Tyr and Trp/Σ-respective competitor neutral amino acids (NAA) ratio and concentrations of other amino acids (AA), known to be involved in the functioning of the central nervous system (CNS) and the synthesis of neurotransmitters, in particular, were used as biochemical markers to assess this likelihood. Factors known to influence plasma AA concentrations such as cortisol and pyridoxal phosphate (PLP, active form of vitamin B6), both modulators of AA intestinal absorption, were examined. Results: Dietary supply of amino acid substrates (precursors) and blood levels of coenzyme/cofactor (vitamin B6 and iron) involved were adequate in both groups and were kept constant throughout the treatment. The rise in plasma cortisol, known to be stimulated under the action of estrogen, was significant (p < 0.05) after the first menstrual cycle and remained higher (although not significantly) than mean baseline and reference normal values at the end of the 6-month OC treatment. Plasma Trp/Σ-specific competitor NAA ratio remained unchanged whereas Tyr/Σ-specific competitor NAA ratio was significantly (p < 0.02) reduced after the sixth artificial menstrual cycle. Conclusion: Although plasma AA biochemical markers cannot accurately assess CNS activity, they seem to be more sensitive than a comprehensive psychometric testing (MMPI) in assessing OC-induced psychological changes.