Molecular imaging of protein-protein interactions: controlled expression of p53 and large T-antigen fusion proteins in vivo

Protein-protein interactions control essential steps in signal transduction pathways and other intracellular processes, and assembly of protein complexes modulates and responds to the regulatory events that exist in living animals. We have used microPET and fluorescence imaging to detect interactions between p53 tumor suppressor and large T antigen (TAg) of SV40 virus in a tetracycline-inducible two-hybrid system. To additionally validate this molecular imaging technique, we investigated whether expression of the reporter gene, comprised of a mutant thymidine kinase from herpes simplex virus 1 fused to green fluorescent protein could quantify relative differences in amounts of interacting hybrid proteins. In HeLa cells stably transfected with the reporter gene and interacting (p53-TAg) or noninteracting (p53 and polyoma virus coat protein) pairs of proteins, treatment with doxycycline produced time- and dose-dependent increases in expression of hybrid proteins. Proportional increases in amounts of reporter gene were produced only in cells expressing p53 and TAg. In mice bearing xenografts of these stably transfected HeLa cells, amounts of hybrid proteins were regulated with doxycycline. Both microPET imaging and biodistribution studies showed time- and dose-dependent increases in accumulation of the reporter substrate 9-(4-[(18)F]-fluoro-3-hydroxymethylbutyl)guanine only in p53-TAg tumors. Fluorescence microscopy of excised tumors also showed corresponding changes in expression of the fusion reporter gene in response to binding of p53 and TAg. These data demonstrate that the imaging two-hybrid system responds in a proportional fashion to increasing amounts of interacting proteins in vivo.     

Leigh disease with mitochondrial DNA A8344G mutation: case report and brief review

Leigh disease, subacute necrotizing encephalomyelopathy, is a neurodegenerative disorder often seen in infancy or childhood but rarely reported in adults. Genetic heterogeneity is well recognized, and the associated etiologies include both mitochondrial and nuclear DNA defects. We describe an infant presenting with developmental delay and then progressive multisystem disorder and neuroradiologic features of Leigh disease. He and his maternal relatives all have the A8344G mitochondrial DNA mutation. However, only minor clinical features are seen in his maternal relatives, with migraine being the most common problem. Additionally the A8344G mitochondrial DNA mutation is associated with spinocerebellar degeneration, other nonspecific mitochondrial encephalomyopathies, atypical Charcot-Marie-Tooth disease, and progressive external ophthalmoplegia. The A8344G mitochondrial DNA mutation may present with Leigh disease or other different atypical clinical features without myoclonic epilepsy and ragged red fibers.     

Morbidity from excessive intake of high energy fluids: the 'squash drinking syndrome'

OBJECTIVE--To identify children suffering morbidity from excessive intake of energy from fluids. DESIGN--Prospective enrolment of outpatients in a supervised reduction of energy rich fluid intake. SETTING--Outpatient paediatric clinic. SUBJECTS--Eight children (four boys, mean age 20.8 months, mean duration of symptoms seven months) who were referred with non-specific symptoms such as poor appetite, poor behaviour at mealtimes, poor weight gain, and loose stools. RESULTS--All children were able to reduce their intake of energy rich fluids, as prescribed. All children demonstrated an improvement in symptoms and an increase in weight. CONCLUSIONS--A careful dietary history, which includes documentation of fluid intake may identify children whose intake of high energy drinks may be excessive. The pathogenesis, symptoms, and response to treatment of these patients are consistent enough to be regarded as a distinct clinical entity: the 'squash drinking syndrome'.     

Open houses and closed rooms: Tokelau housing in New Zealand.

The migrant Tokelau community in New Zealand, through the Wellington Tokelau Association, is playing an active role in partnership with the Wellington School of Medicine to develop a research program to help improve the health of its people. The relationship between crowded homes and health was investigated in six focus groups. While cultural patterns were an essential part of Tokelau hospitality, the decision to "double up" households was often the result of "rational" economic decision making in relation to household expenditures such as rent and food. The implication for public health practitioners is that while overcrowding may be a health hazard for residents, the most effective solutions by the community are higher household income and more flexible housing designs that accommodate multifamily households.     

Child Behavior Ratings: The Influence of Maternal Characteristics and Child Temperament

This study investigated the extent to which maternal characteristics, such as psychological health problems, marital adjustment and confidence in mother/wife roles, influenced how mothers rated the behavior of their first-born children (n = 100) on the Pre-school Behavior Questionnaire. Results showed that these characteristics were powerful predictors of behavior ratings. In contrast, the independent contribution of child temperament ratings was relatively small. It was concluded that child behavior problem and temperament measures may be confounded. Maternal ratings constitute a valuable source of information concerning parent-child interaction which deserve further investigation, especially of their influence on generally accepted measures of child behavioral adjustment.     

Conditioning exercise and premenstrual symptoms

Exercise is commonly listed as a remedy for the premenstrual syndrome (PMS), although no study has proven that it is an effective therapy. Numerous reports have suggested that exercise is associated with improved mood and symptoms. In those reports, however, the diagnosis of PMS was not clearly documented, nor was the exercise carefully controlled. Preliminary evidence suggests that exercise training in ovulatory, sedentary women and intensified training in women athletes decrease mild premenstrual symptoms. Although conditioning exercise is associated with short luteal phase and anovulatory cycles, decreases in mild premenstrual symptoms occur prior to menstrual cycle changes. Controlled studies of PMS and exercise training may not only document an effective, nonpharmacologic therapy for PMS but also clarify the hormonal etiology of this complex biobehavioral phenomenon.