Integrated cell biology/biochemistry/molecular genetics laboratories: the cytoplasmic genome projects

This paper describes an integrated laboratory project for intermediate to advanced undergraduate students. The project spans an entire academic quarter (10 weeks) and involves a series of operations that give students experience with fundamental techniques in cell biology, molecular biology, biochemistry, genomics, and bioinformatics. In the process, the student learning community is strengthened, students gain increasing confidence in their abilities in the laboratory, and data are collected toward the eventual sequencing of a cytoplasmic genome. The culmination of the project is the preparation by students of a paper written in the format of a particularly accessible online journal. Journal of Industrial Microbiology & Biotechnology (2000) 24, 339–344. Received 02 April 1999/ Accepted in revised form 22 November 1999     

Selective inhibition of prostaglandin biosynthesis by gold salts and phenylbutazone

Gold salts and phenylbutazone selectively inhibit the synthesis of PGF_2α and PGE₂ respectively. Lowered production of one prostaglandin species is accompanied by an increased production of the other. Selective inhibition by these drugs was observed in the presence of adrenaline, reduced glutathione and copper sulphate under conditions when most anti-inflammatory compounds inhibited PGE₂ and PGF_2α syntheses equally. It is postulated that selective inhibitors may have a different mode of action in vivo and beneficial effects may be related to the endogenous ratio of PGE to PGF required for normal function.     

Ethical aspects of anti-Alzheimer drugs: experiences of caregivers

The development and use of acetylcholinesterase inhibitors raise ethical issues. Ethical issues concern the consequences of an early diagnosis, the creation of unreasonable hope, possible negative effects of rivastigmine use, problems concerning stopping with rivastigmine, the patient role in decision-making and the possibility of conflicting interests. Within the ethical literature, hypotheses about the meaning of this drug for the patients have been formulated. This research aimed to investigate the experiences of caregivers of patients who used rivastigmine. The data have been collected by semi-structured interviews. The study included 12 caregivers of rivastigmine users. The--preliminary--results seem to indicate that theoretical considerations should be modified in the light of the experiences of caregivers. For example, problematic consequences of an early diagnosis and the creation of unreasonable hope did not appear in this study. Also problems concerning the rising awareness of cognitive decline were not found. In the interest of a further ethical debate concerning the development and use of antidementia drugs it is important to modify these theoretical considerations.     

Pathogenic mutations in the kinesin-3 motor KIF1A diminish force generation and movement through allosteric mechanisms

The kinesin-3 motor KIF1A functions in neurons, where its fast and superprocessive motility facilitates long-distance transport, but little is known about its force-generating properties. Using optical tweezers, we demonstrate that KIF1A stalls at an opposing load of ~3 pN but more frequently detaches at lower forces. KIF1A rapidly reattaches to the microtubule to resume motion due to its class-specific K-loop, resulting in a unique clustering of force generation events. To test the importance of neck linker docking in KIF1A force generation, we introduced mutations linked to human neurodevelopmental disorders. Molecular dynamics simulations predict that V8M and Y89D mutations impair neck linker docking. Indeed, both mutations dramatically reduce the force generation of KIF1A but not the motor’s ability to rapidly reattach to the microtubule. Although both mutations relieve autoinhibition of the full-length motor, the mutant motors display decreased velocities, run lengths, and landing rates and delayed cargo transport in cells. These results advance our understanding of how mutations in KIF1A can manifest in disease.     

Microtubule acetylation promotes kinesin-1 binding and transport

Long-distance intracellular delivery is driven by kinesin and dynein motor proteins that ferry cargoes along microtubule tracks . Current models postulate that directional trafficking is governed by known biophysical properties of these motors-kinesins generally move to the plus ends of microtubules in the cell periphery, whereas cytoplasmic dynein moves to the minus ends in the cell center. However, these models are insufficient to explain how polarized protein trafficking to subcellular domains is accomplished. We show that the kinesin-1 cargo protein JNK-interacting protein 1 (JIP1) is localized to only a subset of neurites in cultured neuronal cells. The mechanism of polarized trafficking appears to involve the preferential recognition of microtubules containing specific posttranslational modifications (PTMs) by the kinesin-1 motor domain. Using a genetic approach to eliminate specific PTMs, we show that the loss of a single modification, alpha-tubulin acetylation at Lys-40, influences the binding and motility of kinesin-1 in vitro. In addition, pharmacological treatments that increase microtubule acetylation cause a redirection of kinesin-1 transport of JIP1 to nearly all neurite tips in vivo. These results suggest that microtubule PTMs are important markers of distinct microtubule populations and that they act to control motor-protein trafficking.     

Cost-Effectiveness of One Year Dementia Follow-Up Care by Memory Clinics or General Practitioners: Economic Evaluation of a Randomised Controlled Trial

Objective

To evaluate the cost-effectiveness of post-diagnosis dementia treatment and coordination of care by memory clinics compared to general practitioners’ care.

Methods

A multicentre randomised trial with 175 community dwelling patients newly diagnosed with mild to moderate dementia, and their informal caregivers, with twelve months’ follow-up. Cost-effectiveness was evaluated from a societal point of view and presented as incremental cost per quality adjusted life year. To establish cost-effectiveness, a cost-utility analysis was conducted using utilities based on the EQ-5D. Uncertainty surrounding the incremental cost-effectiveness ratio (difference in costs divided by difference in effects) was calculated by bootstrapping from the original data.

Results

Compared to general practitioners’ care, treatment by the memory clinics was on average €1024 (95% CI: −€7723 to €5674) cheaper, and showed a non-significant decrease of 0.025 (95% CI: −0.114 to 0.064) quality adjusted life years. The incremental cost-effectiveness point estimate from the bootstrap simulation was € 41 442 per QALY lost if one would use memory clinic care instead of general practitioner care.

Conclusion

No evidence was found that memory clinics were more cost-effective compared to general practitioners with regard to post-diagnosis treatment and coordination of care of patients with dementia in the first year after diagnosis.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00554047","term_id":"NCT00554047"}}NCT00554047     

Sublethal damage during cryopreservation of rainbow trout sperm

Although cellular damage during cryopreservation of freshwater fish spermatozoa has been reported in several studies, there is a lack of correlation between this damage and the fertility rates of eggs using postthawed milt. The apparent lack of such correlation may be due to other undetected sublethal cryodamage, which could affect the cell functionality and viability. This may be extremely important for freshwater fish spermatozoa whose ability to fertilize the egg requires dilution in water or hypoosmotic solutions, an hazardous environment for the cells. This study tested the change in cell permeability during cryopreservation, using Hoechst 33258 to assess cell permeability. The permeability of spermatozoa at different times after dilution in several hypoosmotic media were investigated. In the first trial, fresh semen, sperm diluted in freezing media (CPT), and freeze/thawed semen were studied. Three CPT were tested (Me2SO, DMA, and methanol). In the second trial, the addition of egg yolk as a membrane stabilizer was investigated. Samples were frozen at -20 degreesC/min in a programmable cooler and thawed in a 25 degreesC water bath. Dilution in the CPTs slightly increased the susceptibility of cells to damage but freezing/thawing caused a dramatic increase in the fragility of cells, which were killed in a few seconds after their contact with the hypoosmotic solutions. Egg yolk provided a significant protection to the membrane, allowing the cells a greater and more prolonged survival in the fertilization media. Samples frozen with Me2SO displayed the best results. These results are consistent with the achieved fertility rates that demonstrated sublethal cryodamage in the function of the sperm membrane that was not detected by standard procedures. Copyright 1998 Academic Press.