Gene expression analysis on sections of zebrafish regenerating fins reveals limitations in the whole-mount in situ hybridization method

The caudal fin of adult zebrafish is used to study the molecular mechanisms that govern regeneration processes. Most reports of gene expression in regenerating caudal fins rely on in situ hybridization (ISH) on whole-mount samples followed by sectioning of the samples. In such reports, expression is mostly confined to cells other than those located between the dense collagenous structures that are the actinotrichia and lepidotrichia. Here, we re-examined the expression of genes by performing ISH directly on cryo-sections of regenerates. We detected expression of some of these genes in cell types that appeared to be non-expressing when ISH was performed on whole-mount samples. These results demonstrate that ISH reagents have a limited capacity to penetrate between the regenerating skeletal matrices and suggest that ISH performed directly on fin sections is a preferable method to study gene expression in fin regenerates.

Differential expression of orthologous Dlx genes in zebrafish and mice: implications for the evolution of the Dlx homeobox gene family

Dlx homeobox genes of vertebrates are often organised as physically linked pairs in which the two genes are transcribed convergently (tail-to-tail arrangement). Three such Dlx pairs have been found in mouse, human, and zebrafish and are thought to have originated from the duplication of an ancestral gene pair. These pairs include Dlx1/Dlx2, Dlx7/Dlx3, and Dlx6/Dlx5 (the zebrafish orthologue of Dlx5 is named dlx4). Expression patterns of physically linked Dlx genes overlap extensively. Furthermore, orthologous Dlx genes often show highly similar expression patterns. We analysed Dlx expression during the gastrula and early somitogenesis of the mouse and zebrafish. It was found that expression of the mouse Dlx6 gene takes place in the rostral ectoderm and presumptive olfactory and otic placodes with patterns similar to the previously reported expression of the physically linked Dlx5 gene. However, we observed only very weak expression of the mouse Dlx3 gene at the same stage. This contrasts with the expression of dlx genes in zebrafish where dlx3 and dlx7, but not dlx4 and dlx6 are expressed during gastrulation in the rostral ectoderm and presumptive placodes. Thus, Dlx expression patterns at early stages are better conserved between paralogous pairs of physically linked genes than between orthologous pairs. This suggests that early expression of Dlx genes existed prior to the duplications that led to the multiple pairs of physically linked genes but was differentially conserved in different paralogs in zebrafish and mice.

The zebrafish scyba gene encodes a novel CXC-type chemokine with distinctive expression patterns in the vestibulo-acoustic system during embryogenesis

Chemokines, in addition to their characterized functions as immune modulators, also play a role in developmental processes such as neural cell migration. Although, chemokines have been described in human, mouse and other vertebrate species, they have yet to be characterized in zebrafish. In this paper, we report the isolation and expression analysis of scyba, a zebrafish gene encoding a CXC-type chemokine protein. During early segmentation, scyba transcripts are detected in the midbrain region and the otic placodes. At later developmental stages, scyba expression is restricted to a subset of hindbrain commissural neurons and to the hair-cell sensory patches of the otic vesicle and lateral-line neuromasts.

Cost-effectiveness of coronary artery bypass surgery in octogenarians

OBJECTIVE

The objective of this retrospective cohort study was to determine whether coronary artery bypass graft (CABG) surgery is effective and cost-effective relative to medical management of coronary artery disease (CAD) in the elderly.

SUMMARY BACKGROUND DATA

The aging of the U.S population and the improvements in surgical techniques have resulted in increasing numbers of elderly patients who undergo this surgery. The three randomized, controlled trials (RCTs) that established the efficacy of CABG surgery completed patient enrollment from 19 to 24 years ago excluded patients older than 65 years. Although information regarding outcomes of CABG in this population is mainly available in case series, a major lacuna exists with respect to information on quality of life and cost effectiveness of surgery as compared with medical management.

METHODS

The authors retrospectively formed surgical and medically managed cohorts of octogenarians with significant multivessel CAD. More than 600 medical records of patients older than 80 years who underwent angiography at our institution were reviewed to identify 48 patients who were considered reasonable surgical candidates but had not undergone surgery. This cohort was compared with 176 patients who underwent surgery.

RESULTS

The cost per quality-adjusted life year saved was $10,424. At 3 years, survival in the surgical group was 80% as compared with 64% in the entire medical cohort and 50% in a smaller subset of the medical cohort. Quality of life in patients who underwent surgery was measurably better than that of the medical cohort with utility index scores, as measured by the EuroQoL, (a seven-item quality of life questionnaire) of 0.84, 0.61, and 0.74, respectively.

CONCLUSIONS

Performing CABG surgery in octogenarians is highly cost-effective. The quality of life of the elderly who elect to undergo CABG surgery is greater than that of their cohorts and equal to that of an average 55-year-old person in the general population.

The effect of explantation and neomycin on hair cells and supporting cells in organotypic cultures of the adult guinea-pig utricle

Recent reports suggest that immature hair bundles are observed following aminoglycoside-induced hair-cell loss in the mammalian utricle in vitro as well as in vivo. It is therefore important to document the initial morphological changes associated with both culturing and aminoglycoside application so that degeneration can be clearly distinguished from regeneration. In this study, utricles from adult guinea pigs were maintained in culture for either 3 or 8 days, half being exposed to neomycin for days 2 and 3. They were then processed for microscopical examination and compared with control utricles from animals of the same age. The numbers of hair-cell and supporting-cell nuclei were counted and hair-cell morphology assessed. Bundles were classified as having either stepped (SHB) or unstepped (UHB) stereocilia, and their density determined. The numbers of hair-cell, but not supporting-cell, nuclei declined significantly compared with controls in both untreated and treated explants, the greatest reduction occurring 5 days after neomycin administration. The density of SHBs also declined but there was no significant change in UHB density, resulting in a residual population of hair bundles of more immature appearance in both untreated and treated utricles in vitro than in vivo. Although degenerative events such as hair-cell ejection from, or retraction into, the sensory epithelium were observed, no evidence of regeneration was found.

Integration of a sexuality counseling service into a reproductive health program for persons with mental retardation

A socialization and sexuality counseling program was instituted as an integral part of a gynecologic service begun at the University of Michigan for persons with mental retardation. One hundred three patients were seen between 1986 and 1989 for counseling. Patients were referred for a variety of reasons, the most common being sexual behavior deemed inappropriate by the referring agent (i.e., direct care givers, parents, teachers, workshop supervisors, and other community professionals). Other concerns included sexual abuse, sterilization requests, sexuality and socialization education, marital questions, pregnancy assistance, abortion counseling, and family stress. Treatment techniques included gynecologic examination and follow-up, psychosexual education, psychiatric evaluation and follow-up, and group and individual psychosexual counseling. A majority of the patients improved during treatment. It is proposed that such a counseling program can play a useful role in the preparation of people with mental retardation to live in their communities as they deal with day-to-day decision making and should be an integral part of reproductive health care for this population.

Family views on sterilization for their mentally retarded children

Eighty-eight parents of adolescents or adults with mental retardation answered written and/or telephone questionnaires concerning sterilization and reproductive health choices for their children with mental retardation. The 36 parents whose children were still living at home were more concerned about the capacity for sexual activity in their disabled child than were the 52 parents whose children were living outside the home. Otherwise, the two groups of parents were very similar in their attitudes. The reasons for considering sterilization were parental fear of sexual abuse, unwanted pregnancy and failure of birth control methods. Almost all the parents in this study wanted to participate in decisions concerning the sterilization of their disabled child.