A mutation in the AMPA-type glutamate receptor, glr-1, blocks olfactory associative and nonassociative learning in Caenorhabditis elegans.

The alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-type ionotropic glutamate receptor mediates fast excitatory neurotransmission in the vertebrate brain and is important for synaptic plasticity and the initial induction of long-term potentiation (LTP). This study found that the putative Caenorhabditis elegans AMPA receptor gene, glr-1, plays a significant role in experience-dependent behavior in C. elegans. glr-1 mutants are deficient in an olfactory associative learning task, in which diacetyl (DA) is paired with acetic acid solution. glr-1 mutant nematodes are also impaired in nonassociative learning (habituation) with the same DA stimulus. The C. elegans learning mutants, lrn-1 and lrn-2, are impaired in chemosensory associative learning yet have no deficits in habituation. The results suggest that although associative and nonassociative learning can be genetically dissociated (lrn-1 and lrn-2), they also share some common molecular processes, including glr-1-mediated neurotransmission.

Standard incision or no-scalpel vasectomy?

BACKGROUND: For more than a decade a new method of vas deferens access, the no-scalpel vasectomy (NSV), has been promoted and publicized in the United States, Canada, and other countries and has gained remarkable acceptance. Supporters of NSVs claim fewer hematomas, less bleeding, fewer infections, shorter operating times, less pain, and an enhanced acceptance of vasectomy. METHODS: The records of a series of 619 consecutive vasectomies performed by the same surgeon using both NSV and standard incision techniques were analyzed to compare the incidence of early complications in each. RESULTS: The incidence of complications in the series of vasectomies was virtually the same whether NSV or a conventional method was used. Infections occurred in 0.7% of conventional procedures, compared with 0.6% in NSVs; hematomas occurred in 0.3% of both; and no incisional bleeding was seen after either procedure. CONCLUSIONS: The claims made for NSV remain unsubstantiated. This study indicates that either a standard incision or the NSV method of accessing the vas deferens can yield similarly good results.

Olfactory associative learning in Caenorhabditis elegans is impaired in lrn-1 and lrn-2 mutants.

The C. elegans mutants, lrn-1 and lrn-2, are impaired in associative learning using conditioned taste cues. Both mutants are defective in associative learning about appetitive and aversive events, indicating that lrn-1 and lrn-2 exert effects across motivational boundaries. In a new olfactory associative learning paradigm, in which wild type worms learn to avoid a previously attractive diacetyl odor after it has been paired with an aversive acetic acid solution, lrn-1 and lrn-2 are impaired. Although defective in associative learning using a conditioned olfactory cue, nonassociative learning (habituation and dishabituation) using this same olfactory cue is unaffected. The discovery that lrn-1 and lrn-2 are defective in associative learning with both taste and olfactory cues may suggest that associative learning in different sensory modalities converges on a common genetic pathway in C. elegans that is subserved by lrn-1 and lrn-2.

Cold shock before associative conditioning blocks memory retrieval, but cold shock after conditioning blocks memory retention in Caenorhabditis elegans.

The effects of cooling on associative learning and memory processes in Caenorhabditis elegans were investigated by giving the worms cold shock at various times before or after conditioning. A pretraining cold shock in the 30 min immediately before conditioning and a posttraining cold shock in the 30 min immediately after conditioning both disrupted learning and memory processes tested a short time after conditioning. However, if tested 3 hr after conditioning, worms given a pretraining cold shock demonstrated learned preferences, whereas worms given a posttraining cold shock still had memory deficits. These results suggest that the effects of cold shock on associative learning and memory can be dissociated into effects on memory retrieval and memory retention.

An evaluation of a short-term chronic effluent toxicity test using sheepshead minnow (Cyprinodon variegatus) larvae.

In response to recent changes in National Pollutant Discharge Elimination System (NPDES) permit regulations, rapid (7-day) static renewal toxicity tests have been developed to detect chronic (sublethal and lethal) effect concentrations of municipal and industrial effluents on freshwater and marine/estuarine organisms. This paper evaluates results from short-term (7-day) chronic effluent tests measuring effects on the growth and survival of the larvae of estuarine sheepshead minnow (Cyprinodon variegatus). Growth was the more sensitive endpoint in 52% of the effluent tests; survival was most sensitive in 7% of the tests. Growth and survival were equally sensitive endpoints in 26% of the tests, while there was no effect on either endpoint at the highest test concentration in 15% of the tests. Four short-term chronic tests were conducted concurrently with early life stage (ELS) tests using a common effluent. Effect concentrations were generally (two of three) within one dilution (a factor of three). Comparison of short-term chronic and ELS tests were also conducted with reference single chemicals and the results were slightly better than the effluent comparisons. A series of ten intralaboratory tests and seven interlaboratory tests were conducted to assess the variability among tests results. Toxicity in these tests varied by no more than one test concentration interval. We concluded that this sheepshead minnow test is suitable to estimate chronic values for complex effluents discharged to marine/estuarine environments within the NPDES permit regulations.

Back pain: treatment and prevention in a community hospital.

Because back pain is a widespread and costly condition that tends to recur, treatment must focus on both the amelioration of acute symptoms and prevention over the long term. This paper reports a longitudinal evaluation of a program from a community hospital that emphasizes both these aspects. One hundred twenty patients routinely admitted to this program were randomly assigned to treatment and control groups. These groups were assessed for differences in demonstrated physical strength, mobility, body mechanics, and self-care knowledge, and in levels of self-reported exercise, anxiety, and pain. There were significant immediate gains on physical measures of fitness and in observed body mechanics; patients also reported significant gains in physical capabilities at home and in leisure activities. Self-care knowledge also improved. When assessed one year later, original gains in physical strength and mobility were being maintained, and self-reported physical capabilities also remained high. Although demonstrated knowledge of correct body mechanics declined over this period, it was still significantly greater than before the program. In light of these results, we believe that outpatient programs like the one reported here merit careful consideration in an era of concern about rising costs for primary health care.

What do family physicians see in practice?

Health care problems dealt with in their practices were recorded by seven family physicians over a period of 1 year (two others recorded for 3 months), each diagnosis being coded according to the Canuck Disease Classification Index. Problems were classified into four types: physical, psychosocial, diseases of choice (or lifestyle) and diseases of social impact. More than 85% of the 23 108 problems recorded were physical in origin and had physical manifestations. More time was spent on routine checkups and treatment of respiratory disease than on any other activity. Venereal disease and alcoholism were infrequent problems. The family physician is in a favourable position to act as health educator and counsellor and must be throughly trained in the physical aspects of disease.