Relationship between enzymatic activity and oligomerization state of tyrosine hydroxylase

The native form of tyrosine hydroxylase (TH) is a homotetramer which consists of four identical subunits each with an MW of approximately 60 kD. The relationships between the catalytic activity of TH and oligomerization of the enzyme have not yet been characterized. We have investigated, by deletion and/or substitution mutagenesis, the involvement of the leucine zipper (LZ) motifs in the oligomer formation of TH and its relation to catalytic activity. Our results demonstrate that deletion of the carboxyl-terminal LZ (LZ-C) abolishes tetramer formation. Interruption of the other two LZ motifs (LZ-A and LZ-B), located in a central region of the catalytic domain by substitution of Leu to Pro at residues 294 and 301 or 386 and 393 has no effect on the tetramer formation of TH. However, the interruption of LZ-A and LZ-B abolishes TH enzymatic activity. The substitution of Leu residues 188 and 190 with Pro at the regulatory domain of TH reduces enzymatic TH activity without affecting tetramer formation. Thus, LZ-C is required for tetramer formation, while LZ-A and LZ-B seem to be involved in the catalytic activity without affecting the tetramer formation of TH.     

ACUTE EFFECTS OF MOVEMENT VELOCITY ON BLOOD LACTATE AND GROWTH HORMONE RESPONSES AFTER ECCENTRIC BENCH PRESS EXERCISE IN RESISTANCE-TRAINED MEN

This study aimed to compare the effects of different velocities of eccentric muscle actions on acute blood lactate and serum growth hormone (GH) concentrations following free weight bench press exercises performed by resistance-trained men. Sixteen healthy men were divided into two groups: slow eccentric velocity (SEV; n = 8) and fast eccentric velocity (FEV; n = 8). Both groups performed four sets of eight eccentric repetitions at an intensity of 70% of their one repetition maximum eccentric (1RMecc) test, with 2-minute rest intervals between sets. The eccentric velocity was controlled to 3 seconds per range of motion for SEV and 0.5 seconds for the FEV group. There was a significant difference (P < 0.001) in the kinetics of blood lactate removal (at 3, 6, 9, 15, and 20 min) and higher mean values for peak blood lactate (P = 0.001) for the SEV group (9.1 ± 0.5 mM) compared to the FEV group (6.1 ± 0.4 mM). Additionally, serum GH concentrations were significantly higher (P < 0.001) at 15 minutes after bench press exercise in the SEV group (1.7 ± 0.6 ng · mL⁻¹) relative to the FEV group (0.1 ± 0.0 ng · mL⁻¹). In conclusion, the velocity of eccentric muscle action influences acute responses following bench press exercises performed by resistance-trained men using a slow velocity resulting in a greater metabolic stress and hormone response.     

Recent advances in genetic research on schizophrenia

Evidence for genetic factors in schizophrenia is reviewed with regard to family, twin and adoption studies, and recent advances in molecular genetic technology are applied to explore possible gene loci susceptible to schizophrenia. Application of neuropsychological and neuroimaging methodologies are also reviewed with an aim to develop criteria for defining phenotypes for genetic studies.Plenary Session, Twelfth Joint Annual Conference of Biomedical Sciences, April 20, 1997, Taipei, Taiwan.     

Pathogenicity of clinical Salmonella enterica serovar Typhimurium isolates from Thailand in a mouse colitis model

Salmonella enterica serovar Typhimurium (S. Typhimurium [STM]) is a leading cause of nontyphoidal salmonellosis (NTS) worldwide. The pathogenesis of NTS has been studied extensively using a streptomycin-pretreated mouse colitis model with the limited numbers of laboratory STM strains. However, the pathogenicity of the clinically isolated STM (STMC) strains endemic in Thailand in mice has not been explored. The aim of this study was to compare the pathogenicity of STMC strains collected from Northern Thailand with the laboratory STM (IR715) in mice. Five STMC isolates were obtained from the stool cultures of patients with acute NTS admitted to Maharaj Nakorn Chiang Mai Hospital in 2016 and 2017. Detection of virulence genes and sequence type (ST) of the strains was performed. Female C57BL/6 mice were pretreated with streptomycin sulfate 1 day prior to oral infection with STM. On Day 4 postinfection, mice were euthanized, and tissues were collected to analyze the bacterial numbers, tissue inflammation, and cecal histopathological score. We found that all five STMC strains are ST34 and conferred the same or reduced pathogenicity compared with that of IR715 in mice. A strain-specific effect of ST34 on mouse gut colonization was also observed. Thailand STM ST34 exhibited a significant attenuated systemic infection in mice possibly due to the lack of spvABC-containing virulence plasmid.     

Blockade of glutamatergic transmission as treatment for dyskinesias and motor fluctuations in Parkinson's disease

Summary In animal models of Parkinson's disease (PD), glutamate antagonists diminish levodopa (LD)-associated motor fluctuations and dyskinesias. We sought to investigate if these preclinical observations can be extended to the human disease, by evaluating the effects of three non-competitive NMDA antagonists (dextrorphan, dextromethorphan and amantadine) on the motor response to LD in patients with advanced PD. In four separate trials, adjuvant therapy with these drugs reduced LD-induced dyskinesias and motor fluctuations. These findings support the view that drugs acting to inhibit glutamatergic transmission at the NMDA receptor can ameliorate LD associated motor response complications.     

Morphology of the endometrial microvasculature during early placentation in the rat

Summary The morphology of the uterine microvasculature during early placentation was investigated by light microscopy, scanning electron microscopy of microvascular corrosion casts and transmission electron microscopy in rats 26 and 50 h after initiation of implantation. Increased vascular permeability at implantation sites was observed as a positive blue-dye test, spacing of vessels, and as localized extravasations of resin from postcapillary venules in the center of the endometrium. The subepithelial capillary plexus in the primary decidual zone adjacent to the blastocyst was shut down 50 h after initiation of implantation, most probably due to swelling of the metabolically activated endothelium and volume expansion of the decidual cells. This phenomenon coincided with the mesometrial orientation of the inner cell mass of the blastocyst; it may be a uterine mechanism to direct the ectoplacental cone toward the patent vessels in the mesometrial portion of the uterus. The remaining vessels at implantation sites were generally fewer, larger in diameter, more irregular in caliber, and more uniformly oriented along the implantation axis than their counterparts at inter-implantation sites. No vascular sprouts were observed during the interval studied.     

Proffered papers 14.00–15.00 Tuesday 16 September 2003

Background  ERCP-directed brush cytology is used to sample lesions of the pancreatic and biliary ducts and the ampulla of Vater. With conventional preparations, the sensitivity and specificity range from 44% to 63% and 80% to 98%, respectively, and increased N : C ratio, nuclear molding and loss of honeycombing are reliable features of malignancy. The performance and morphology of specimens prepared by ThinPrep, a liquid-based cytology technique is mostly unknown.
Methods  The laboratory information system was searched for all cases prepared by ThinPrep. Patient disease classification of benign or malignant was determined by linkage with the provincial cancer registry and was the gold standard against which sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. True positives and negatives were reviewed to identify predictive cytomorphologic features.
Results  Between 1996 and 2001, there were 149 ThinPrep specimens; 55 (37%) were reported as positive for malignancy and 94 (63%) as negative. Disease was classified as malignant in 86 (58%) patients and benign in 63 (42%). There were 42 false negative, 11 false positive, 52 true negative, and 44 true positive cytology results. Sensitivity was 51.2% (CI; 40.2 : 62.0), specificity 82.5% (CI; 70.5 : 90.6), and PPV and NPV 80.0% (CI; 66.6 : 89) and 55.3% (CI; 44.7 : 65.5), respectively. Cell groups with crowded, enlarged, irregular nuclei and nuclear features of vesicular chromatin and large, multiple irregular nucleoli correlated with malignant disease, while monolayered sheets of uniform columnar cells, regular nuclei and a finely granular chromatin correlated with benign disease.
Conclusions  The performance of ThinPrep brushings from this anatomic site equals conventional preparations. Cytomorphologic features of malignancy are more frequent and pronounced with ThinPrep.     

Biofloc Technology: Emerging Microbial Biotechnology for the Improvement of Aquaculture Productivity

With the significant increases in the human population, global aquaculture has undergone a great increase during the last decade. The management of optimum conditions for fish production, which are entirely based on the physicochemical and biological qualities of water, plays a vital role in the prompt aquaculture growth. Therefore, focusing on research that highlights the understanding of water quality and breeding systems’ stability is very important. The biofloc technology (BFT) is a system that maximizes aquaculture productivity by using microbial biotechnology to increase the efficacy and utilization of fish feeds, where toxic materials such as nitrogen components are treated and converted to a useful product, like a protein for using as supplementary feeds to the fish and crustaceans. Thus, biofloc is an excellent technology used to develop the aquaculture system under limited or zero water exchange with high fish stocking density, strong aeration, and biota. This review is highlighted on biofloc composition and mechanism of system work, especially the optimization of water quality and treatment of ammonium wastes. In addition, the advantages and disadvantages of the BFT system have been explained. Finally, the importance of contemporary research on biofloc systems as a figure of microbial biotechnology has been emphasized with arguments for developing this system for better production of aquaculture with limited natural resources of water.Key words: biofloc, BFT, aquaculture, microbes, water quality, wastes