Effect of fibronectin- and collagen I-coated titanium fiber mesh on proliferation and differentiation of osteogenic cells

The objective of this study was to evaluate the effects of fibronectin and collagen I coatings on titanium fiber mesh on the proliferation and osteogenic differentiation of rat bone marrow cells. Three main treatment groups were investigated in addition to uncoated titanium fiber meshes: meshes coated with fibronectin, meshes coated with collagen I, and meshes coated first with collagen I and then subsequently with fibronectin. Rat bone marrow cells were cultured for 1, 4, 8, and 16 days in plain and coated titanium fiber meshes. In addition, a portion of each of these coating treatment groups was cultured in the presence of antibodies against fibronectin and collagen I integrins. To evaluate cellular proliferation and differentiation, constructs were examined for DNA, osteocalcin, and calcium content and alkaline phosphatase activity. There were no significant effects of the coatings on cellular proliferation as indicated by the DNA quantification analysis. When antibodies against fibronectin and collagen I integrins were used, a significant reduction (p < 0.05) in cell proliferation was observed for the uncoated titanium meshes, meshes coated with collagen, and meshes coated with collagen and fibronectin. The different coatings also did not affect the alkaline phosphatase activity of the cells seeded on the coated meshes. However, the presence of antibodies against fibronectin or collagen I integrins resulted in significantly delayed expression of alkaline phosphatase activity for uncoated titanium meshes, meshes coated with collagen, and meshes coated with collagen and fibronectin. Calcium measurements did not reveal a significant effect of fibronectin or collagen I coating on calcium deposition in the meshes. Also, no difference in calcium content was observed in the uncoated titanium meshes and meshes coated with fibronectin when antibodies against fibronectin or collagen I integrins were present. Meshes coated with both collagen I and fibronectin showed significantly higher calcium content when cultured in the presence of antibodies to collagen and fibronectin integrins. A similar phenomenon was also observed for collagen-coated meshes cultured in the presence of antibodies to fibronectin integrins. No significant differences in osteocalcin content were observed between the treatment groups. However, all groups exposed to antibodies against fibronectin integrins showed a significant decrease in osteocalcin content on day 16. These results show that a fibronectin or collagen I coating does not stimulate the differentiation of rat bone marrow cells seeded in a titanium fiber mesh.     

Transforming growth factor-beta 1, 2, and 3 can inhibit epithelial tissue outgrowth on smooth and microgrooved substrates

In this study, we describe the influence of parallel surface microgrooves, and of TGF-beta, on the outgrowth of corneal epithelial tissue. Microgrooves (depth 1 microm, width 1-10 microm) were made in polystyrene culturing surfaces. These surfaces were left untreated, or loaded with TGF-beta 1, 2, or 3 (6.0 ng/cm(2)). Subsequently, epithelial explants from bovine corneas were placed on the experimental surfaces. After 9 days of culturing, tissue outgrowth was evaluated. Furthermore, the tissue cultures were analyzed histologically. It was shown that epithelial tissue grew from the explants over all experimental surfaces. On microgrooved surfaces outgrowth proceeded in the direction of the grooves, rather than perpendicular to the grooves. The addition of each type of TGF-beta resulted in a reduction of outgrowth. However, outgrowth remained directed by the grooves. Further, the explants had shrunk after TGF treatment. Histology showed that this shrinkage was not related to alpha-smooth muscle actin expression in the explants. We conclude that microgrooves can direct, and TGF-betas can inhibit the outgrowth of epithelial tissue. This finding could be useful in biomaterial applications where the growth of epithelial tissue needs to be discouraged.     

Peptide specificity and HLA restriction do not dictate lymphokine production by allergen-specific T-lymphocyte clones.

Human and murine CD4+ T lymphocytes can be subdivided into distinct subsets [T-helper type 0 (Th0), Th1 or Th2], based on their lymphokine production profiles. Not much is known about the factors that determine these restricted lymphokine secretion profiles. Peptide specificity and human leucocyte antigen (HLA) restriction may be such factors. As it is well established that allergen-specific T lymphocytes from atopic individuals and non-atopic controls differ in their lymphokine secretion profile, we studied two allergen-specific T-lymphocyte clones (TLC) with identical peptide specificity and HLA restriction that were generated from the peripheral blood of an atopic donor and a non-atopic control donor. The two CD4+ TLC recognize the same epitope (20-33) of the house dust mite Dermatophagoides pteronyssinus major allergen Der p II. Both TLC recognize the epitope in an HLA-DQB1*0602-restricted manner. However, the lymphokine production profiles of these TLC show clear differences after allergen-specific or polyclonal activation. As expected, TLC JBD4 from the atopic donor produced high levels of interleukin-4 (IL-4) without detectable interferon-gamma (IFN-gamma), whereas TLC PBA1 from the non-atopic donor produced both IFN-gamma and IL-4 upon allergen-specific or polyclonal activation. Inasmuch as both TLC recognized the same epitope of Der p II in association with the same HLA-DQ molecule, these data suggest that peptide specificity and HLA restriction of human allergen-specific TLC do not dictate their lymphokine secretion profile.     

Polyneuronal innervation of skeletal muscle in new-born rats and its elimination during maturation.

1. The events taking place during the elimination of polyneuronal innervation in the soleus muscle of new-born rats have been studied using a combination of electrophysiological and anatomical techniques. 2. Each immature muscle fibre is supplied by two or more motor axons which converge on to a single end-plate. There was no sign of electrical coupling between muscle fibres receiving multiple synaptic inputs. By the end of the second week after birth virtually all muscle fibres are innervated by only a single motor axon. 3. The average tension produced by individual motor units, measured in terms of the percentage of the total muscle twitch tension, declined dramatically during the first 2 weeks after birth. During this period there was no significant change in the number of motor neurones innervating the soleus muscle. Thus, the disappearance of polyneuronal innervation reflects a decrease in the number of peripheral synapses made by each motor neurone. 4. The decline in motor unit size was delayed, but not ultimately prevented, by the early surgical removal of all but a few motor axons to the soleus muscle. This procedure also caused a delay in the removal of polyneuronal innervation involving the remaining motor units. 5. Following a crush of the soleus nerve in neonatal animals, regenerating axons usually returned to the original end-plates. Polyneuronal innervation was extensive at early stages of re-innervation and it disappeared during the second week after birth just as in normal muscles. 6. Cross-innervation of neonatal muscles by an implanted foreign nerve caused a rapid disappearance of cholinesterase at denervated original end-plates and in most fibres prevented re-innervation by the original nerve. In the small proportion of fibres that did become innervated through both the foreign and original nerves the end-plates were more than 1 mm apart, and both foreign and original nerve end-plates could persist indefinitely. 7. Many cross-innervated fibres received multiple inputs through the foreign nerve. Some foreign end-plates were separated by distances ranging up to 1 mm. Polyneuronal innervation through the foreign nerve was completely eliminated during maturation but over a slightly longer period than in normal muscles. Apparently the elimination process can act over a distance up to but not much more than 1 mm. 8. These observations suggest that there are several factors influencing the elimination of redundant inputs in immature muscles. Individual motor neurones appear to have an inherent tendency to withdraw the majority of their original complement of peripheral terminals. The determination of which particular synapses are to survive, however, seems to be made in the periphery by a selection among all the synapses that innervate a limited region of each muscle fibre. There may be a competitive interaction among synapses in which those belonging to smaller motor units are less likely to be eliminated, thereby leading to a relatively uniform size of the motor units in the soleus.     

Serological identification of pig enterotoxigenic Escherichia coli strains not belonging to the classical serotypes.

Escherichia coli strains isolated from pigs suspected to have succumbed to E. coli enterotoxicosis and not belonging to the commonly incriminated (classical) serotypes (O8:K87:K88, O45:K88, O138:K81:K88, O141:K85:K88, O147:K89:K88, O149:K91;K88, and O157:K88) were tested for enterotoxigenicity in the ligated gut test (LGT) using pig intestine. Of 202 strains tested, 54 strains belonging to 13 different O groups were positive in the LGT. Four of these strains had K88 antigen and one possessed K99 antigen. The majority of the strains was not agglutinated by any of the standard OK antisera. Four new K antigens ("K200", "K442", "K2346" and "K2347") were provisionally designated. K200 was found in pig enterotoxigenic strains belonging to O group 8 and carrying flagellar antigen H31 and in non-enterotoxigenic non-motile strains of O group 8, as well as in O group 20 strains isolated from calves succumbing to E. coli septicemia in two countries. The provisional antigen K2346 was encountered in 18 enterotoxigenic strains with various O antigens from two countries. It is proposed to include these two K antigens into the international E. coli antigens scheme. Attempts to demonstrate a common antigen in the nonclassical enterotoxigenic strains lacking K88 and K99 antigens failed.     

Suppression of spontaneous breathing during high-frequency jet ventilation

Conditions which suppress spontaneous breathing activity during high-frequency jet ventilation (HFJV) were analysed in Yorkshire piglets under pentobarbital anesthesia. The highest P_aCO₂ at which the animals did not breathe against the ventilator (apnea point) was established during different patterns of ventilation, either by changing the minute volume or by adding CO₂ to the inspiratory gas. Arterial oxygen tension was maintained throughout the study above 80 mm Hg. An elevation of ventilatory rate increased the apnea point, suggesting a progressive suppression of spontaneous breathing. This suppression did not depend on the amount of lung stretch during insufflation, because at higher rates lower tidal volumes were used. Suppression also appeared to be independent of insufflatory flow, i.e. the velocity of lung stretch. At higher frequencies end-expiratory airway pressure (P_EE) increased and there appeared to be a positive relationship between the apnea point and P_EE. In a separate series this positive relationship between the apnea point and P_EE was confirmed. A hysteresis effect in this relationship, however, suggests that other than jet frequency, lung volume rather than positive end-expiratory pressure (PEEP) is a major determinant of suppression of spontaneous breathing activity during HFJV.     

Fertility in older women

Giving advice on fertility based solely on a woman's age is hazardous and, for many individual women career choices and career development can be followed by successful pregnancies, but abundant population data now document declining fertility and fecundability with age. These data have important implications both for fertility counseling and for contraceptive practive. The menopause is the obvious endpoint of the reproductive years, but strong and consistent demographic data indicate that fertility declines considerably with age and that reproductive capacity is likely to end 5-10 years before the menopause. Age at menopause is unaffected by previous childbearing or oral contraception. A late menarche is associated statistically with early menopause, but there has been no substantial observed change in the age at menopause to compare with the ever earlier menarche that has occured in the Western world ove the last century. Very poor nutrition appears to lower the age at menopause in India and Papua New Guinea, but this does not seem to be a factor in determining individual age at menopause in Western societies. Cigarette smoking is associated with an earlier age at menopause. Age specific probabilities of sterility for modern American and English populations have been estimated. Using an exponential model developed by Pittenger and data from a number of noncontracepting populations, Gray has predicted that the likelihood of permanent sterility at age 35 is just under 20%; at age 40 it is about 40%; and at age 45 it is 80%. Only a few attempts have been made to test these predictions for modern populations. Bongaarts, using data based on the 1976 US National Survey of Family Growth published by Mosher in 1982, estimated that the prevalence of infertility among normal women after 12 months' pregnancy exposure increases with age: 20-24 years 6.7%, 25-29 years 10.8%, 30-34 years 16.1%, and 35-39 years 22.9%. the decline in reproductive efficiency that accompanies increasing maternal age includes substantial rise in spontaneous abortion probability and first an increase in the probability of multiple ovulation and pregnancy and then a marked decrease, especially after 45 years; and a slow but definite increase in the incidence of congential anomalies, both chromosomal and nonchromosomal. Several mechanisms can be proposed for the decline of fertility that precedes the menopause, including: intercourse frequency decreases with age in all societies; anovulatory cycles increase in frequency after age 40, but only among women who develop oligomenorrhea; increased incidence of chromosomal trisomy manifesting as Down's Syndome of the newborn is a well known phenomenon after the age of about 35; aging of the reproductive tract; and diseases of the reproductive tract. Some attempt to make an individual assessment of prediction of fecundability based on recent reproductive preformance may be reasonable when advising women seeking help with either infertility or contraception.     

Boric acid single dose pharmacokinetics after intravenous administration to man

Eighth young adult male volunteers with a basic (alimentary) plasma boric acid concentration of <0.10–0.46 mg/l were given a single dose of boric acid (562–611 mg) by 20 min IV infusion. The plasma concentration curves, followed for 3 days, best fitted a three-compartment open model, although two subjects had to be left out due to inconstant basal plasma concentration values or failure to fit to the three-compartment model. The 120 h urinary excretion was 98.7±9.1% of dose, Cl_tot 54.6±8.0 ml/min/1.73 m², t_1/2 21.0±4.9 h and distribution volumes V₁, V₂, and V₃: 0.251±0.099, 0.456±0.067 and 0.340±0.128 l/kg.     

Donor genetic variants as risk factors for thrombosis after liver transplantation: A genome-wide association study

Thrombosis after liver transplantation substantially impairs graft- and patient survival. Inevitably, heritable disorders of coagulation originating in the donor liver are transmitted by transplantation. We hypothesized that genetic variants in donor thrombophilia genes are associated with increased risk of posttransplant thrombosis. We genotyped 775 donors for adult recipients and 310 donors for pediatric recipients transplanted between 1993 and 2018. We determined the association between known donor thrombophilia gene variants and recipient posttransplant thrombosis. In addition, we performed a genome-wide association study (GWAS) and meta-analyzed 1085 liver transplantations. In our donor cohort, known thrombosis risk loci were not associated with posttransplant thrombosis, suggesting that it is unnecessary to exclude liver donors based on thrombosis-susceptible polymorphisms. By performing a meta-GWAS from children and adults, we identified 280 variants in 55 loci at suggestive genetic significance threshold. Downstream prioritization strategies identified biologically plausible candidate genes, among which were AK4 (rs11208611-T, p = 4.22 × 10⁻⁰⁵) which encodes a protein that regulates cellular ATP levels and concurrent activation of AMPK and mTOR, and RGS5 (rs10917696-C, p = 2.62 × 10⁻⁰⁵) which is involved in vascular development. We provide evidence that common genetic variants in the donor, but not previously known thrombophilia-related variants, are associated with increased risk of thrombosis after liver transplantation.     

Allergy to pine nuts in a bird fancier

A patient is described with the bird-egg syndrome who experienced an anaphylactic reaction after eating some of her parrot's food (pine nuts: Pinus pinea ). Specific IgE against this nut and another pine nut ( P cembra ) was demonstrated by RAST. Cross-reactivity between these botanically related seeds was shown by RAST inhibition. Besides avian antigens, bird food antigens should be taken into consideration when symptoms of allergy occur on exposure to birds.