Cyclin E constrains Cdk5 activity to regulate synaptic plasticity and memory formation

Cyclin E is a component of the core cell cycle machinery, and it drives cell proliferation by regulating entry and progression of cells through the DNA synthesis phase. Cyclin E expression is normally restricted to proliferating cells. However, high levels of cyclin E are expressed in the adult brain. The function of cyclin E in quiescent, postmitotic nervous system remains unknown. Here we use a combination of in vivo quantitative proteomics and analyses of cyclin E knockout mice to demonstrate that in terminally differentiated neurons cyclin E forms complexes with Cdk5 and controls synapse function by restraining Cdk5 activity. Ablation of cyclin E led to a decreased number of synapses, reduced number and volume of dendritic spines, and resulted in impaired synaptic plasticity and memory formation in cyclin E-deficient animals. These results reveal a cell cycle-independent role for a core cell cycle protein, cyclin E, in synapse function and memory.

Ethnicity and symptom expression in patients with acute schizophrenia

Chinese patients have been largely ignored in the literature examining ethnic differences in schizophrenia. This study examined demographics and symptom profiles of Euro-, African-, Chinese-American, and Latino inpatients with schizophrenia. Chinese-American patients had fewer symptoms, hospitalizations, and least amount of education compared to other groups. Cultural and clinical implications are discussed.

Modeling distribution and abundance of soybean aphid in soybean fields using measurements from the surrounding landscape

Soybean aphid (Aphis glycines Matsumura) is a severe pest of soybean in central North America. Outbreaks of the aphid in Ontario are often spotty in distribution, with some geographical areas affected severely and others with few or no aphid populations occurring in soybean for the duration of the season. A. glycines spend summers on soybean and overwinter on buckthorn, a shrub that is widespread in southern Ontario and is commonly found in agricultural hedgerows and at the margins of woodlots. A. glycines likely use both short distance migratory flights from buckthorn and longer distance dispersal flights in the search for acceptable summer hosts. This study aims to model colonization of soybean fields by A. glycines engaged in early-season migration from overwintering hosts. Akaike's information criterion (AIC) was used to rank numerous competing linear and probit models using field parameters to predict aphid presence, colonization, and density. The variable that best modeled aphid density in soybean fields in the early season was the ratio of buckthorn density to field area, although dramatic differences in relationships between the parameters were observed between study years. This study has important applications in predicting areas that are at elevated risk of developing economically damaging populations of soybean aphid and which may act as sources for further infestation.

The independent effects of left ventricular ejection fraction on short-term outcomes and resource utilization following hospitalization for heart failure

BACKGROUND

While depressed left ventricular ejection fraction is clearly associated with poor long-term outcome in heart failure (HF), the effect of ejection fraction on short-term outcomes and resource utilization following hospitalization for HF remains unclear.

HYPOTHESIS

We evaluated the independent effect of depressed ejection fraction (< or = 40%) on short-term outcomes and resource utilization following hospitalization for HF.

METHODS

The study population included 443 consecutive patients hospitalized for DRG 127 (HF and shock) with known ejection fraction. For each patient, we assessed the hospitalization cost (1995 US$), length of stay, in-hospital mortality, 30-day mortality, and 30-day readmission rates.

RESULTS

Despite similar disease severity at admission, patients with ejection fraction < or = 40% (Group 1) had longer length of stay (4.0 vs. 3.7 days; p = 0.03), a tendency toward higher hospitalization cost ($3,054 vs. $2,770; p = 0.08), more readmissions for any cause (0.4 vs. 0.3; p = 0.05) and for HF (0.2 vs. 0.1; p = 0.01), but similar in-hospital (2.5 vs. 2.6%) and 30-day mortality (4.0 vs. 4.6%) compared with patients with ejection fraction > 40% (Group 2). In multivariate analyses, Group 1 patients were more likely to have higher than median hospitalization cost [odds ratio (OR) = 1.98; 95% confidence intervals (CI) = 1.02-3.91] and longer than median hospital stay (OR = 1.68; CI = 1.08-3.91); they were also more likely to be readmitted for any cause (OR = 2.07; CI = 1.15-3.78) or for HF (OR = 5.71; CI = 1.64-21.94), and they tended to have a higher 30-day incidence of death or readmission (OR = 1.65; CI = 0.96-2.84).

CONCLUSIONS

Depressed left ventricular ejection fraction is associated with higher resource utilization and readmission rates following hospitalization for HF. Greater focus on patients with depressed ejection fraction may increase cost savings from HF disease management programs.

Unicompartmental or total knee replacement

Between 1989 and 1992 we had 102 knees suitable for unicompartmental knee replacement (UKR). They were randomised to receive either a St Georg Sled UKR or a Kinematic modular total knee replacement (TKR). The early results demonstrated that the UKR group had less complications and more rapid rehabilitation than the TKR group. At five years there were an equal number of failures in the two groups but the UKR group had more excellent results and a greater range of movement.

The cases were reviewed by a research nurse at 8, 10 and 12 years after operation. We report the outcome at 15 years follow-up. A total of 43 patients (45 knees) died with their prosthetic knees intact. Throughout the review period the Bristol knee scores of the UKR group have been better and at 15 years 15 (71.4%) of the surviving UKRs and 10 (52.6%) of the surviving TKRs had achieved an excellent score. The 15 years survivorship rate based on revision or failure for any reason was 24 (89.8%) for UKR and 19 (78.7%) for TKR. During the 15 years of the review four UKRs and six TKRs failed.

The better early results with UKR are maintained at 15 years with no greater failure rate. The median Bristol knee score of the UKR group was 91.1 at five years and 92 at 15 years, suggesting little functional deterioration in either the prosthesis or the remainder of the joint. These results justify the increased use of UKR.