Nuclear elongation of dissociated newt spermatids in vitro and their nuclear shortening by antimicrotubule agents

Dissociated newt spermatids with an initial cell length of 20-35 microns increased in length at an average rate of 35-46 microns during 5 days of culture at 22 degrees C. 10(-5) M vinblastine sulfate shortened the length of nearly all the spermatids of various initial lengths to that of round spermatids within 24 h at 22 degrees C. Application of vinblastine to the spermatids immediately following initiation of nuclear elongation caused the nuclei to become completely round within 1 h. 3 X 10(-6) M colcemid, 10(-4) M colchicine, 2 X 10(-5) M nocodazole and 10(-4) M griseofulvin also shortened the spermatid length. The effects of these five antimicrotubule agents were irreversible. Neither 10(-4) M beta-, gamma-lumicolchicine nor 1.0 micrograms/ml cytochalasin B (CB) had any effect on spermatid elongation. Spermatids incubated at 4 degrees C for 6 days shortened by 20-50%, but after transfer to 22 degrees C they started to elongate. An ultrastructural study showed that during nuclear elongation the number of microtubules increased in proportion to the elongation, and that the microtubules surrounded the whole nucleus from its apical to caudal end. After addition of vinblastine many microtubular crystals appeared in the cytoplasm of the spermatids. It was concluded that microtubules are a prerequisite for nuclear elongation of newt spermatids, and it is speculated that microtubules act directly in the initiation and continuation of the nuclear elongation of newt spermatids.     

Yeast populations on the tropical timber tree species Milicia excelsa

H. LI, E. VEENENDAAL, N.A. AB SHUKOR, J.R. COBBINAH AND C. LEIFERT. 1995. Yeast populations found on the tropical timber tree species Milicia excelsa showed very little diversity at the genus and species level. Of 62 isolates, 87% were Cryptococcus laurentii , 5% Candida humicola , 3% Candida curvata , 1.5% Candida membranaefaciens , 1.5% Rhodotorula minuta and 1.5% Rhodotorula rubra . Approximately half of the Crypt. laurentii strains had unusual metabolic profiles when compared with the Crypt. laurentii strains in the profile library of the APILAB yeast identification software. All isolated strains were non-pathogenic and did not show antagonism against Botrytis cinerea in an in vitro plate assay. However, three strains of Crypt. laurentii suppressed disease development of B. cinerea in a leaf disk bio-assay. This indicates that protection of leaves against opportunistic fungal diseases may be part of the ecological function of Crypt. laurentii populations on Milicia leaves and the potential of this yeast species for biological control.     

Repair and regeneration of osteochondral defects in the articular joints

People suffering from pain due to osteoarthritic or rheumatoidal changes in the joints are still waiting for a better treatment. Although some studies have achieved success in repairing small cartilage defects, there is no widely accepted method for complete repair of osteochondral defects. Also joint replacements have not yet succeeded in replacing of natural cartilage without complications. Therefore, there is room for a new medical approach, which outperforms currently used methods. The aim of this study is to show potential of using a tissue engineering approach for regeneration of osteochondral defects. The critical review of currently used methods for treatment of osteochondral defects is also provided. In this study, two kinds of hybrid scaffolds developed in Hutmacher's group have been analysed. The first biphasic scaffold consists of fibrin and PCL. The fibrin serves as a cartilage phase while the porous PCL scaffold acts as the subchondral phase. The second system comprises of PCL and PCL-TCP. The scaffolds were fabricated via fused deposition modeling which is a rapid prototyping system. Bone marrow-derived mesenchymal cells were isolated from New Zealand White rabbits, cultured in vitro and seeded into the scaffolds. Bone regenerations of the subchondral phases were quantified via micro CT analysis and the results demonstrated the potential of the porous PCL and PCL-TCP scaffolds in promoting bone healing. Fibrin was found to be lacking in this aspect as it degrades rapidly. On the other hand, the porous PCL scaffold degrades slowly hence it provides an effective mechanical support. This study shows that in the field of cartilage repair or replacement, tissue engineering may have big impact in the future. In vivo bone and cartilage engineering via combining a novel composite, biphasic scaffold technology with a MSC has been shown a high potential in the knee defect regeneration in the animal models. However, the clinical application of tissue engineering requires the future research work due to several problems, such as scaffold design, cellular delivery and implantation strategies.     

Multienzyme microbiosensor based on electropolymerized o-phenylenediamine for simultaneous in vitro determination of acetylcholine and choline

The electrochemical biosensors based on poly(o-phenylenediamine) (PoPD) and acetylcholinesterase (AChE) and choline oxidase (ChO) enzymes were fabricated on carbon fibre (CF) substrate. The electropolymerized PoPD was used to reduce the interfering substances. The electrode assembly was completed by depositing functionalized carbon nano tubes (FCNTs) and Nafion (Naf). Amperometric detection of acetylcholine (ACh) and choline (Ch) were realized at an applied potential of +750 mV vs Ag/AgCl (saturated KCl). At pH 7.4, the final assembly, Naf-FCNTs/AChE-ChO((10:1))/PoPD/CF(Elip), was observed to have high sensitivity towards Ch (6.3±0.3 μA mM(-1)) and ACh (5.8±0.3 μA mM(-1)), linear range for Ch (K(M)=0.52±0.03 mM) and ACh (K(M)=0.59±0.07 mM), and for Ch the highest ascorbic acid blocking capacity (97.2±2 1mM AA). It had a response time of <5s and with 0.045 μM limit of detection. Studies on different ratio (ACh/Ch) revealed that 10:1, gave best overall response.     

Annual Risk of Tuberculous Infection Using Different Methods in Communities with a High Prevalence of TB and HIV in Zambia and South Africa

Background

The annual risk of tuberculous infection (ARTI) is a key epidemiological indicator of the extent of transmission in a community. Several methods have been suggested to estimate the prevalence of tuberculous infection using tuberculin skin test data. This paper explores the implications of using different methods to estimate prevalence of infection and ARTI. The effect of BCG vaccination on these estimates is also investigated.

Methodology/Principal Findings

Tuberculin surveys among school children in 16 communities in Zambia and 8 in South Africa (SA) were performed in 2005, as part of baseline data collection and for randomisation purposes of the ZAMSTAR study. Infection prevalence and ARTI estimates were calculated using five methods: different cut-offs with or without adjustments for sensitivity, the mirror method, and mixture analysis. A total of 49,835 children were registered for the surveys, of which 25,048 (50%) had skin tests done and 22,563 (90%) of those tested were read. Infection prevalence was higher in the combined SA than Zambian communities. The mirror method resulted in the least difference of 7.8%, whereas that estimated by the cut-off methods varied from 12.2% to 17.3%. The ARTI in the Zambian and SA communities was between 0.8% and 2.8% and 2.5% and 4.2% respectively, depending on the method used. In the SA communities, the ARTI was higher among the younger children. BCG vaccination had little effect on these estimates.

Conclusions/Significance

ARTI estimates are dependent on the calculation method used. All methods agreed that there were substantial differences in infection prevalence across the communities, with higher rates in SA. Although TB notification rates have increased over the past decades, the difference in cumulative exposure between younger and older children is less dramatic and a rise in risk of infection in parallel with the estimated incidence of active tuberculosis cannot be excluded.     

Terpenoid,Benzenoid, and Phenylpropanoid Compounds in the Floral Scent of <Emphasis Type="Italic">Vanda</Emphasis> Mimi Palmer

Vanda Mimi Palmer is the product of a cross between Vanda Tan Chay Yan and Vanda tessellata. The flower of this hybrid produces a sweet-smelling fragrance during day time at the open-flower stage. This study aimed to investigate the floral scent constituents in Vanda Mimi Palmer. Scent emission analysis of this orchid was carried out at different time points in a 24-h cycle and also at different floral developmental stages. A comparison was also made on the volatiles emitted by Vanda Mimi Palmer and both of its parents. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the scent of Vanda Mimi Palmer was dominated by terpenoid, benzenoid, and phenylpropanoid compounds. The identified terpenoids were ocimene, linalool oxide, linalool, and nerolidol; while the benzenoid and phenylpropanoid compounds were methylbenzoate, benzyl acetate, phenylethanol, and phenylethyl acetate. The emission of terpenoid, benzenoid, and phenylpropanoid compounds was developmentally and temporally regulated. Comparison of the volatiles emitted by both of its parents showed that the scent of Vanda Mimi Palmer is dissimilar to that of its fragrant parent, V. tessellata.